Physical and Chemical Injuries of the Oral Cavity

High-Speed Instrumentation

The development of high-speed dental engines and hand-pieces necessitated investigation of the possible effects which their use might have on pulp tissue, and numerous reports of such studies have been published.

Bernier and Knapp reported a study on high-speed instrumentation utilizing various speeds up to 100,000 rpm. They found evidence of mild pulpal damage, but, in addition, observed a new type of lesion which they termed the ‘rebound response’. This consisted variously in: (1) an alteration in ground substance, (2) edema, (3) fibrosis, (4) odontoblastic disruption, and (5) reduced predentin formation in a region directly across the pulp opposite the cavity site or at a distant pulpal site, and thought to be caused by waves of energy transmitted to the pulp focused into a certain region by the pulpal walls. The significance of this phenomenon is still not clear.

Swerdlow and Stanley in their study involving 450 human teeth found that speeds over 50,000 rpm with coolants were less injurious to the pulp than lower speeds. They concluded that the combination of high speed, controlled temperature, and light load produced minimal pathologic pulpal alteration. When heavy loads were used, even coolants did not minimize inflammatory responses. Extending this investigation to 13 operative techniques, Diamond and his coworkers found that the 300,000 rpm air-water spray—No. 35 carbide bur technique—provided all the cutting efficiency of a high-speed instrument without producing extended or burn lesions and caused the highest incidence of reparative dentin formation, a favorable protective reaction. A speed of 250,000 rpm with water coolant was reported by Nygaard-Ostby to produce even less pulpal reaction than the conventional (6,000 rpm) machine without water-spray. Caviedes-Bucheli and coworkers in their study found that substance P expression is increased in tooth where cavity preparation is done and concluded that it may have an important clinical significance in terms of inflammation and pain experience.

The practicability of use of accelerated hand-piece speeds has been accurately summarized by Stanley and Swerdlow, who stated: ‘In principle, high speed techniques approach the ideal but at the same time these methods can be easily abused… properly used, ultraspeed is an extremely safe and efficient method of reducing tooth structure’.

Effect of Air Abrasive Technique

In the air abrasive technique, aluminum oxide sprayed under pressure is used as an abrasive for the cavity preparation and surface treatment. The main drawback of this procedure is, it does not allow the operators’ stereognostic ability to control the depth of cutting. However Ferrazzano et al, based on their study in 60 mandibular third molar concluded that the macroscopic size and shape of cavities is connected to working distance, while working time is important to determine the depth of preparation. Also the abrasive dust is a potential health hazard to the operator and the patient. Nowadays it is used only to clean the pit and fissures prior to the application of sealants.

Effect of Ultrasonic Technique

The use of ultrasonic equipment for cutting cavities in teeth has been advocated because it involves less heat, noise, and vibration in contrast to rotary instruments. Essentially, the technique consists in the conversion of electrical energy into mechanical energy in the form of vibration of a tiny cutting tip, approximately 29,000 vibrations per second with an amplitude of about 0.0014 inch. Aluminum oxide abrasive in a liquid carrier is washed across this tip, and the vibration of the particles in turn results in a rapid reduction of tooth substance.

The effects of this technique, as used in cavity preparation, on the tooth and dental pulp have been evaluated by a number of investigators whose results are in essential agreement. Zach and Brown, Healey and his coworkers, and Lefkowitz among others have found that there are no remarkable differences in the reaction of the dental pulp to the preparation of cavities by the steel bur, the diamond stone or the ultrasonic instrument. This again emphasizes that only the dentinal injury itself is important, not how this injury is produced.

Mitchell and Jensen, studying the effect of steel bur and ultrasonic cavity preparation on the human tooth, also reported that no differences could be observed in the reaction of the pulp to these two techniques. Mild hyperemia, hemorrhage and a slight neutrophilic and lymphocytic infiltration of the pulp tissue immediately below the cut dentinal tubules were noted during the 6–12 day period following cavity preparation by either means. After several weeks the late reaction consisted in slight, irregular secondary dentin deposition and the formation of a ‘calciotraumatic’ line, a hematoxyphilic line between the regular dentin and the postoperative dentin apparently representing a disturbance in dentin formation at the time of the operative procedure.

Lasers

Laser is an acronym for Light Amplification by Stimulated Emission of Radiation. It is an electro-optical device which, upon stimulation, can convert jumbles of light waves into an intense, concentrated, uniform, narrow beam of monochromatic light with an energy source of great intensity and exceptional flexibility. The radiation may be continuous or modulated, or the emission may occur in short pulses. This high-intensity radiation can be focused on an extremely small area, approximately 1 micron in diameter, because of the small angle of divergence and coherency of the beam. Light photons of characteristic wavelengths are produced, amplified, and filtered to produce the laser beam. Carbon dioxide and neodymium:yttrium-aluminum-garnet (Nd:YAG) lasers are most commonly used. The main problem with laser cutting of hard dental tissues is the generation of heat and forbidden tactile control.

Lasers are used in dental practice to coalesce pits and fissures to eliminate retention sites for bacteria, to desensitize the exposed root surfaces, to make the hard tissue surfaces rough to promote bonding as an alternative to acid etching, to vaporize the carious tissue, to vaporize the organic tissues in the root canal in endodontic procedures, cavity preparation, restoration removal, treatment of dentinal sensitivity, caries prevention and bleaching.

Effects on Teeth

The effects of laser on teeth were first reported by Stern and Sognnaes, who found that exposure of intact enamel, caused a glass like fusion of the enamel, whereas dentin exposed to laser exhibited a definitive charred crater. Chalky spots, craters, or small holes in enamel may also be produced under other conditions. Scanning electron microscopic analysis showed the effects of laser on dentin vary from no effects to disruption of the smeared layer to actual melting and recrystallization of the dentin, depending on power level, duration of exposure, and color of the dentin. Although it has been shown that selective deep destruction of carious tooth substance can be accomplished, the practicality of its use in removing carious lesions is still questionable. Laser irradiation alters the dentin structure and produces surface layers that give the appearance of being more enamel-like. The laser-modified surface may be more resistant to demineralization; hence, many investigators are proposing continued development of the laser for caries prevention.

Open dentin surface exposed to laser results in melting and closure of the orifices of the dentin and this property is used to treat dentin hypersensitivity.

Bleaching of stained teeth has also been accomplished by lasing.

Effects on Pulp

The pulps of teeth in animals subjected to laser radiation have been described by Taylor and his associates as showing severe pathologic changes, including hemorrhagic necrosis with acute and chronic inflammatory cell infiltration. The odontoblastic layer also underwent coagulation necrosis, although the severity of the response varied with the amount of radiation.

Zinc Oxide and Eugenol

It is used routinely as a temporary filling material or root canal sealer. Eugenol of this cement fixes cells, depresses the cell respiration, and reduces the neural transmission in vitro. There is almost universal agreement that zinc oxide and eugenol is the least injurious of all filling materials to the dental pulp. Not only is there no irritation produced by this substance, but actually it exerts a palliative and sedative effect on the mildly damaged pulp, since it inhibits synthesis of prostaglandins and leukotrienes. It seems to be such a bland substance that it may lack even the necessary irritating properties requisite to the stimulation of secondary dentin formation. In view of these findings, zinc oxide and eugenol is the material of choice for use over injured pulps or as a base in deep cavity preparations.

Zinc Phosphate (Oxyphosphate) Cement

This particular cement is widely used in dentistry both as a protective base in deep cavities before the insertion of the restoration and also in cementing cast inlays, crowns, and other similar restorations. The majority of investigators have reported significant deleterious effects on the pulp when the material is placed in cavities, the actual injurious agent supposedly being the phosphoric acid.

Gurley and Van Huysen prepared cavities in teeth of young dogs and filled them with zinc phosphate cement. After approximately 1½ months they found hyperemia and inflammatory cell infiltration of the pulp with disarrangement of the odontoblastic layer. Secondary dentin had formed under the shallower cavities. The more severe pulpal reactions occurred under the deeper cavities.

Studies on human teeth, such as those by Manley, by Shroff, and by Kramer and McLean, show that hyperemia or hemorrhage with inflammatory cell infiltration of the pulp accompanied by reduction in the size and number of the odontoblasts occurs after placement of this cement in prepared cavities.

The studies generally indicate that zinc oxyphosphate cement is an irritant when placed in the base of a deep cavity, particularly in bulk, although the human pulp may be able to localize this reaction in most instances. When this cement is used in shallow cavities, it is relatively innocuous and reportedly serves a useful function in the stimulation of secondary dentin formation.

Polycarboxylate or polyacrylate cements have properties comparable to those of the phosphate cements, but have a low degree of pulpal irritation similar to that of the zinc oxide-eugenol cements.

Self-polymerizing Acrylic Resin

Self-curing resins were extensively used as restorative materials, particularly in anterior teeth. There is evidence to indicate, however, that these resins may cause serious damage to the dental pulp. Still, not all investigations are in complete agreement.

Conventional Composite Resins

These are restorative materials developed chiefly because methyl methacrylate or unfilled acrylic resins have restrictive characteristics such as low hardness and strength, a high coefficient of thermal expansion and a lack of adhesion to tooth structure. The resin matrix is a compromise between epoxy and methacrylate resins. This resin is combined with a filler of dispersed particles of varying types in relatively high concentration. While most conventional composite resins are chemically activated, some are now marketed whose cure is based on light activation.

The biologic properties of the composite resins show the same irritational characteristics as the unfilled acrylic resins. For this reason, the same measures should be taken to protect the pulp from possible injury, especially when the cavity preparation is deep. A calcium hydroxide base is preferable to a zinc oxide and eugenol base because of the possible interaction of eugenol and resin.

Microfilled Composite Resins

These are a newer group of resins which contain the same resin matrix as the conventional composite resins but differ in that the size of the filler is much smaller than in the conventional resin. The biologic properties of the microfilled resins, including their irritational effects on the pulp, are comparable to those of the conventional composite resins. Thus, some pulpal protection is necessary under deep cavities.

The many experimental studies cited would indicate superficially that the majority of restorative materials used in dentistry today are dangerous because of the serious effects on the dental pulp which they often induce. It is true that many of these materials are potentially injurious. Nevertheless, literally millions of restorations with these substances are placed each year, and clinical experience has shown that, unless actual pulp exposure has occurred, the death rate of dental pulps directly attributable to the restorative material is extremely low. Even the occurrence of clinical symptoms of pulp injury is uncommon. Although this seems contradictory to experimental evidence, it should be appreciated that most cavities prepared by the dentist in which these materials are inserted are to repair a destructive carious lesion. The presence of this carious lesion, in contrast to the experimental cavities prepared in sound human and animal teeth, has usually induced the deposition of secondary dentin and has caused a certain amount of dentinal sclerosis, and these reactions offer considerable protection to the pulp. It is on this basis that the dentist is justified in continuing to use these filling materials. There is a need, however, for continued study of this general problem.

Cement Bases

A cement base is a layer of cement commonly used beneath the dental restoration either to encourage recovery of the injured pulp or to protect the pulp against the injuries. Intermediary base materials that are commonly used under permanent restorations include zinc phosphate cement, zinc oxide-eugenol cement, and calcium hydroxide cement. Ideally, a cement base should be biologically compatible with the dental pulp and such is the case with zinc oxide-eugenol and calcium hydroxide. However, zinc phosphate cement, when placed against dentin, acts as an irritant to the dental pulp because of the acid content which varies between pH 3.5 and 6.6, as discussed previously.

Cavity Liners

Cavity liners are aqueous or volatile organic liquid suspensions or dispersions of zinc oxide or calcium hydroxide that can be applied in a relatively thin film to the surface of a cavity. They may also be solutions of resins in an organic solvent to which has been added calcium hydroxide or zinc oxide, or aqueous suspensions of calcium hydroxide in methylcellulose. The cavity liner provides the beneficial effects of zinc oxide and calcium hydroxide as thin films in shallow cavities and, in addition, neutralizes the free acid of zinc phosphate and silicate cements. The cavity liners themselves have no effect on dental pulp and, in fact, actually form a chemical barrier to provide reliable protection for the pulp under certain deep restorations.

Stanley has compared the protective effect of reparative dentin with cavity liners and bases, and generally concluded that: (1) pulpal tissue beneath preoperatively formed reparative dentin is safe from most subsequent procedures; (2) cavity liners and/or bases, should be employed since the completeness of the reparative dentin barrier cannot be ascertained; (3) the unrestored tooth being utilized as an abutment lacks reparative dentin and is more subject to the damaging effects of chemical agents because of patent dentinal tubules; (4) although 2 mm of primary dentin between the floor of the cavity preparation and the dental pulp is usually a sufficient protective barrier, the condensation of amalgam or gold foil, as well as the chemical irritation of cements and self-curing resins, may render this thickness of protection insufficient; (5) age changes in the tooth, with the production of reparative dentin in the involved area, are of no recognizable benefit regarding pulp protection; (6) high-speed, water-cooled cutting techniques produce an average incidence of reparative dentin formation of under 20%; even less reparative dentin formation is produced if more than 1 mm of primary dentin remains beneath the cavity preparation; (7) if reparative dentin does not form within the first 50 days following a restorative procedure, then there will be none; (8) nearly 20 postoperative days are required for new odontoblasts to differentiate and produce reparative dentin, and it has been shown that an average of 100 productive days of matrix formation is required to produce a reparative dentin barrier of 0.15 mm; (9) final cementation of restorations need not be delayed in allowing time for reparative dentin to form, since the use of cavity-lining materials is a reasonable substitute; and (10) cavity varnish and calcium hydroxide lining materials appear capable of protecting pulp if used appropriately.

Cavity Varnishes

Cavity varnishes are solutions of one or more resins from natural gums, synthetic resins, and rosin in organic solvents. It is generally agreed that varnishes may be of aid in reducing postoperative sensitivity, but their film thickness is insufficient to provide thermal insulation. This film also acts as a semipermeable membrane so that certain types of ions penetrate it, while others do not. It has been found also that varnishes are effective in reducing the microleakage of fluids around the margins of restorations.

While cavity varnishes themselves appear to have no significant effect upon a dental pulp, neither do they have a sedative effect. Therefore, in deep restorations, it may be advisable to utilize calcium hydroxide or zinc oxide-eugenol cements first, and then apply the varnish over this base.

Etiology

In a review of the subject by Nadler and Meklas, the causes of bruxism have been described as: (1) local, (2) systemic, (3) psychologic, and (4) occupational.

Local factors are generally associated with some form of mild occlusal disturbance which produces mild discomfort, and chronic, even though unrecognized, tension. It has been suggested that in many cases bruxism becomes a firm habit as a result of an unconscious attempt by the patient to establish a greater number of teeth in contact or to counteract a local irritating situation. In children the habit is frequently associated with the transition from the deciduous to the permanent dentition and may result from an unconscious attempt to place the individual tooth planes so that the musculature will be at rest.

Systemic factors have been proposed as etiologically significant, but the role of most of these is difficult to assess. Gastrointestinal disturbances, subclinical nutritional deficiencies, and allergy or endocrine disturbances have all been reported as causative factors. A hereditary background has been described in some cases.

Psychologic factors are believed by some investigators to be the most common cause of bruxism. High levels of anxiety, stress, and emotional tension may be expressed through a number of nervous habits, one of which may be bruxism. Thus, when a person suffers from fear, rage, rejection, or a variety of other emotions which he/she is unable to express, these become hidden in the subconscious but are expressed periodically by numerous means. It has been observed that bruxism is common in mental institutions. Bruxism is a manifestation of nervous tension in children also and may be related to chronic biting or chewing of toys. Polysomnographic studies suggested that sleep bruxism episodes are part of sleep arousal response. The sleep arousal response is nothing but sudden change in the depth of sleep. Besides the sleep bruxism appears to be a disturbance in the dopaminergic system.

Occupations of certain types favor the development of this habit. Athletes engaged in physical activities often develop bruxism, although the exact reason for this is uncertain. Occupations, in which the work must be unusually precise, such as that of the watchmaker, are prone to cause bruxism. Voluntary bruxism is also recognized in those persons who habitually chew gum, tobacco, or objects such as toothpicks or pencils. Although voluntary, this too is a nervous reaction and may lead eventually to involuntary or subconscious bruxism.

Clinical Features

The person who engages in bruxism performs the typical grinding or clenching motions during sleep or subconsciously when awake. These may be associated with a grinding or grating noise. The symptomatic effects of this habit have been reviewed by Glaros and Rao, who have divided them into six major categories: (1) effects on the dentition, (2) effects on the periodontium, (3) effects on the masticatory muscles, (4) effects on the temporomandibular joint, (5) head pain, and (6) psychologic and behavioral effects.

When the habit is firmly established, severe wearing or attrition of the teeth may occur, not only occlusal wear, but also interproximal wear which produces sensitivity. On both surfaces actual facets may be worn in the teeth. As the bruxism continues, there may be loss of integrity of the periodontal structures, resulting in loosening or drifting of teeth or even gingival recession with alveolar bone loss. Temporomandibular joint disturbances are also reported to occur as a result of the traumatic injury of continuous tooth impact without normal periods of rest. Hypertrophy of the masticatory muscles, particularly the masseter muscle, may interfere with maintenance of the rest position, cause trismus, and alter occlusion and the opening and closing pattern of the jaws.

Finally, while it has been suggested that bruxism may give rise to facial pain and headache as well as psychologic and behavioral effects, these are very difficult manifestations to evaluate and correlate.

Treatment and Prognosis

If the underlying cause of the bruxism is an emotional one, the nervous factor must be corrected if the disease is to be cured. Removable splints to be worn at night may be constructed to immobilize the jaws or to guide the movement so that periodontal damage is minimal. Recently Botulinum toxin (Botox) has been very successful in treating the grinding and clenching of bruxism. Botox when injected into the masseter muscle, weakens the muscle enough to stop the grinding and clenching, but not so much as to interfere with chewing or facial expressions. RC DiFrancesco and coworkers suggest that there is a positive correlation between sleep-disordered breathing and bruxism and stated that there was an important improvement of bruxism after adenotonsillectomy based on their study of 69 children. If the disease is left untreated, severe periodontal and/or temporomandibular disturbances may result.

Clinical Features

Although fracture of teeth may occur at any age, children are especially prone to sustain this type of injury. The prevalence of tooth fracture is difficult to assess or evaluate, particularly since minor chipping of teeth is common. As might be expected, boys are more frequently involved than girls. There is a definite predilection for involvement of maxillary teeth, with between 75 and 90% of fractures occurring there (Fig. 12-3).

There are several classifications of fractured teeth, the simplest being only whether or not the fracture line involves the pulp. A more detailed classification is that of Ellis, who divides all traumatized anterior teeth (for these constitute the vast majority of such injuries) into nine classes:

The clinical manifestation as well as the treatment and prognosis of the fractured tooth depend chiefly upon whether the dental pulp is pierced by the fracture and whether the crown or the root of the tooth is involved. If there is crown fracture without pulp involvement, vitality of the tooth is usually maintained, although there may be mild pulp hyperemia even when the overlying dentin is relatively thick. If the dentin over the pulp is exceedingly thin, bacteria may penetrate the dentinal tubules, infect the pulp and produce pulpitis, leading to death of the pulp. When vitality is maintained, usually a layer of secondary dentin is deposited over the involved dentinal tubules. The tooth may be sore and slightly loose because of the traumatic injury, but severe pain is usually absent.

A fractured tooth crown which exposes the pulp is a more serious problem, but pulp exposure does not necessarily imply that death of the pulp will occur. In some cases the exposure can be capped by calcium hydroxide, and a dentinal bridge will form as a part of the healing reaction. Pulpotomy or pulpectomy may often be necessary; however, since the pulp becomes infected almost immediately after the injury.

Root fractures are somewhat uncommon in young children, since their tooth roots are not completely formed and the teeth have some resilience in their sockets. It occurs in patients between the ages of 10 and 20 years and most are traumatic in origin. Root fractures involve mostly the middle third of the root and are horizontal. When fracture does occur, the tooth is loose and sore and there may be displacement of the coronal portion of the tooth. Most of the time tooth becomes nonvital after fracture. Some teeth may be repaired by forming a layer of reparative dentin along the pulp wall and cementum on the outer surface, or form granulation tissue between the fractured segments. Few may remain vital with resorption of the sharp edges of the fractured fragments.

In certain situations where the injury is sufficient to cause root fracture, fragments of cementum may be severed from dentin and is called cemental tear.

Histologic Features

Healing in such cases may be of several types. The most satisfactory form of healing is the union of the two fragments by calcified tissue, and this is analogous to the healing of a bony fracture. The clot between the root fragments is organized, and this connective tissue is subsequently the site of new cementum or bone formation. There is nearly always some resorption of the ends of the fragments, but these resorption lacunae ultimately are repaired. If the apposition between the two fragments is not close, the union is by connective tissue alone. It appears likely that the repair process can be organized from connective tissue cells in both the pulp and the periodontal ligament.

Treatment and Prognosis

The site, direction, and size of the crack or fracture dictates the choice of the treatment. It ranges from stabilization with a stainless steel band or crown to endodontic treatment and restoration. If untreated, CTS can lead to severe pain, possible pulpal necrosis and periapical abscess. Unfortunately, management of CTS is not always successful. In some cases, such as in vertical root fractures (split root) in single rooted teeth, the only treatment option is tooth extraction.

Clinical Features

Ankylosis of the permanent tooth seldom manifests clinical symptoms unless there is a concomitant pulp infection which may be the underlying cause. If there is an extensive area of the root surface involved, the tooth may give a dull, muffled sound on percussion rather than the normal sharp sound. The fact that this condition exists may become apparent only at the time of extraction of the tooth, when considerable difficulty will be encountered, sometimes necessitating surgical removal.

Radiographic Features

If the area of ankylosis is of sufficient size, it may be visible on the radiograph. There is loss of the normal thin radiolucent line surrounding the root that represents the periodontal ligament, with a mild sclerosis of the bone and apparent blending of the bone with the tooth root.

Histologic Features

Microscopic examination reveals an area of root resorption which has been repaired by a calcified material, bone or cementum, which is continuous with the alveolar bone. The periodontal ligament is completely obliterated in the area of the ankylosis (Fig. 12-4).

Treatment and Prognosis

There is no treatment for ankylosis. Ankylosed teeth have a good prognosis and, unless removed for some other reason, should serve well indefinitely.

Clinical Features

Pain during movement, occlusal derangement, abnormal mobility, gingival lacerations, crepitus on movement, trismus, loss of sensation of the involved side, and ecchymosis are common features of mandibular fracture.

Treatment

Like other fracture management jaw fractures are also treated by reduction and immobilization. Complications include nonunion, malunion, and fibrous union.

Etiology

The etiology of the solitary bone cyst is unknown, although a number of theories have been proposed and at least one, the trauma—hemorrhage theory has been rather widely accepted. Howe and also Sieverink have carried out extensive reviews of the literature and pointed out the wide acceptance of the theory of origin from intramedullary hemorrhage following traumatic injury. Hemorrhage occurring within the medullary spaces of bone after trauma heals in most cases by organization of the clot and eventual formation of connective tissue and new bone. According to the traumatic theory, the clot breaks down and leaves an empty cavity within the bone. Steady expansion of the lesion occurs secondary to altered or obstructed lymphatic or venous drainage. This expansion tends to cease when the cyst-like lesion reaches the cortical layer of bone, so that expansion of the involved bone is not a common finding in the solitary bone cyst.

It is not at all unusual; however, for the patient to be unable to recall any traumatic injury to the jaw. This may indicate that an injury so mild that the patient would not be aware of it or remember it, is sufficient to cause this lesion to develop. In the series reported by Howe, only slightly over 50% of the patients gave a history of trauma, the time lag between injury and discovery of the lesion varying from one month to 20 years.

Other theories of origin, reviewed by Whinery, have included:

Clinical Features

The traumatic cyst occurs most frequently in young persons, the median age being 18 years in a series of 45 cases reviewed and reported by Gardner and Stoller. According to Howe, over 75% of cases occur in the second decade of life. There is no definite sex predilection although many series have shown the males being affected more commonly than females. Although it has been stated that the posterior portion of the mandible is more commonly involved than the anterior, numerous cases have been reported in the incisor region, since in the young person this area contains hemopoietic marrow. The maxilla has been known to develop the solitary bone cyst, but only on extremely rare occasions. In some cases enlargement of the mandible has been observed, but often the lesion is discovered during routine radiographic examination of the patient. In the majority of cases the pulps of the teeth in the involved area are vital, and this is important to ascertain, because the vital teeth should not be sacrificed. The presenting complaint may be swelling or rarely pain.

When the cavity is opened surgically, it is found to contain either a small amount of sero-sanguinous fluid, shreds of necrotic blood clot, fragments of fibrous connective tissue, or nothing. The dentist is frequently astonished to open into an empty space in bone and find that it has no clinically demonstrable membrane. It was reported by Toller in one case that the hydrostatic intracystic pressure was exceptionally low and comparable with capillary pressure, quite unlike that in other cysts of the jaw.

Radiographic Features

Radiographic examination usually reveals a rather smoothly outlined radiolucent area of variable size, sometimes with a thin sclerotic border, depending upon the duration of the lesion. Some traumatic cysts may measure only a centimeter in diameter (Fig. 12-5), whereas others may be so large that they involve most of the molar area of the body of the mandible as well as part of the ramus. When the radiolucency appears to involve the roots of the teeth, the cavity may have a lobulated or scalloped appearance extending between the roots of these teeth (Fig. 12-6). Seldom is there any displacement of teeth and, in many cases, the lamina dura appears intact. Rodrigues and Estrela reported a case of traumatic bone cyst in upper premolar-molar region, mimicking a large periapical lesion.

Care must be taken to differentiate the small solitary traumatic cyst occurring in the molar area and appearing as a round or ovoid radiolucent area associated with vital teeth from the lingual salivary gland depression of the mandible (q.v.) which has a similar radiographic appearance. However, the latter lesion is usually located below the mandibular canal, whereas the traumatic cyst usually lies above it.

Histologic Features

Histologic examination of the solitary bone cyst may reveal a thin connective tissue membrane lining the cavity, but no other significant features. Sometimes no such membrane is demonstrable. Waldron had the opportunity to study a solitary bone cyst in toto in a resected mandible. His case exhibited a thin connective tissue membrane and, in addition, an extensive osteophytic reaction on the outer surface of the cortical plate (Fig. 12-7). There may be presence of few red blood cells, blood pigments, or giant cells adhering to the bone surface.

Treatment and Prognosis

Since the definitive diagnosis of the solitary bone cyst cannot be established without surgical exploration, the dentist usually opens into the cavity, attempts to enucleate a lining and, in the course of manipulation, reestablishes bleeding into the lesion. If the cavity is then closed, it has been found that healing and filling of the space by bone occur in most cases in 6–12 months. Seldom is a second surgical procedure necessary. If the space is a large one, bone chips have been used to aid in filling the defect with good results.

The extreme rarity of these lesions in older patients would suggest that not only may they be self-limiting, but at least some are capable of complete and spontaneous remission.

Clinical Features

In the three reported series of cases, approximately 75% of the focal osteoporotic bone-marrow defects of the jaws occurred in women, and they involved the mandible in approximately 85% of the cases. In nearly every instance the lesions were asymptomatic and discovered only during routine radiographic examination.

Radiographic Features

This lesion, which has a predilection for the mandibular molar area, generally appears as a radiolucency of variable size, a few millimeters to a centimeter or more, with a poorly defined periphery indicative of lack of reactivity of adjacent hone (Fig. 12-8A).

Histologic Features

The tissue removed from these defects consists of either normal red marrow, fatty marrow or a combination of the two (Fig. 12-8B). Megakaryocytes and small lymphoid aggregates may be present. The trabeculae of bone usually present in the sections are long, thin, irregular, and devoid of an osteoblastic layer.

Treatment

The radiographic appearance of these lesions is not sufficiently characteristic to permit diagnosis with certainty, and for this reason they must be investigated surgically to rule out osteomyelitis, traumatic bone cyst, and other odontogenic tumors. Once the diagnosis has been established, no additional treatment is necessary.

Clinical Features

The majority of patients with this type of lesion are middle-aged or older and present with a complaint of a nonspecific, poorly localized pain, tenderness, or discomfort in the maxilla. Extraoral or intraoral swelling is also frequently evident. Careful questioning of the patient usually reveals a history of some type of surgical procedure involving the maxilla and maxillary sinus, frequently 10–20 years previously. When content of the mucocele is infected, the lesion is called mucopyocele. Interestingly, it has been emphasized by Ohba and his associates among others that this lesion is more common in Japan than in America or Europe, possibly because of the higher incidence of maxillary sinusitis in Japan. Yamamoto and Takagi in their study involving 60 cases reported that postoperative maxillary cyst accounted for 19.5% of all oral cystic lesions.

Radiographic Features Radiographic examination shows a well-defined unilocular radiolucent area closely related to the maxillary sinus, often appearing to encroach upon the sinus but anatomically separate from it, as may be demonstrated by injection of the sinus with a radiopaque material. A filling defect of the cyst can then be seen (Fig. 12-9A).

Histologic Features

The surgical cyst is lined by pseudostratified ciliated columnar epithelium identical with that of the maxillary sinus (Fig. 12-9B). If infection or inflammation is present, squamous metaplasia may be found. The wall of the cyst is composed of fibrous connective tissue with or without inflammatory cell infiltration.

Treatment

The treatment of this lesion consists in enucleation of the cyst. It does not tend to recur.

Tipping Movement

The exact movements which a tooth will undergo and the exact position it will assume after the application of orthodontic force will depend upon the degree and direction of the force and the position of the fulcrum around which the force acts. The general statement can be made, however, that pressure upon a tooth results in the resorption of bone in the direction of the application of force and compensatory new bone formation on the opposite side of the tooth, the tension side (Fig. 12-10).

The initial reaction on the pressure side is a compression of the periodontal ligament which, if excessive and prolonged, may result in ischemia with hyalinization and/or actual necrosis of tissue (Fig. 12-11B). On the opposite side under excessive force there may be actual tearing of the periodontal fibers and small capillaries with hemorrhage into the area. With reasonable forces, the periodontal ligament on the tension side of the tooth demonstrates stretching and widening of the periodontal space. Within a matter of hours or at the most a few days, large numbers of osteoclasts make their appearance along the surface of the bone under pressure, and resorption begins. This continues until the force of the pressure has been entirely dissipated.

New trabeculae of bone on the tension side become evident early and appear as thin, elongated spicules arranged parallel to the periodontal fibers and confluent with them at their bony attachment (Fig. 12-11A). These spicules show evident osteoblastic activity along the sides and the end adjacent to the tooth, but usually there is intense osteoclastic activity at the ends of the spicules away from the tooth. As stabilization occurs, the alveolar bone gradually assumes its compact pattern that existed before movement occurred.

A secondary but most important occurrence is the deposition of new spicules of bone on the outer surface of the labial plate in instances of pressure in the labial direction. This serves to maintain the thickness of the already thin labial plate and prevent its perforation by the tooth. It is not entirely certain why resorption of even compact bone occurs before resorption of cementum and the tooth root. It is known that resorption of calcified tissues is favored by increased local vascularity, and the hypothesis has been advanced in explanation that the bone of the alveolus is in a more vascular environment than the cementum when orthodontic pressure is applied, particularly since ischemia of the periodontal ligament adjacent to the cementum is the usual situation.

It is generally recognized that the teeth of young persons respond much more rapidly and with less applied force to orthodontic movements than do the teeth of older adults. Although differences do exist in the chemical constitution of bone at varying ages, the difference in orthodontic response is probably due to variation in general tissue reactivity and local vascularity. Although bone retains the ability to undergo resorption throughout life, the degree of the stimulus needed to evoke this response shows dramatic differences between the various age groups.

Extrusive Movement

Extrusion of a tooth by an orthodontic appliance is similar to normal tooth eruption. The tissue changes induced by this form of movement consist apposition of new bone spicules at the alveolar crest and at the fundus of the alveolus arranged in a direction parallel to the direction of force. The direction of the spicules then is parallel to the long axis of the tooth and tends to increase the height of the alveolar crest. The normal width of the apical periodontal ligament is maintained by the new bony spicules here formed in the same direction. The relation between the tooth and the alveolus tends to remain constant.

Intrusive or Depressive Movement

The application of orthodontic force in such a manner as to cause depression of a tooth results in tissue changes that are the opposite of those found during extrusion, or elongation. In tooth depression, resorption of bone occurs at the apical area and around the alveolar margin. New bone formation is actually minimal.

Tissue Reactions during Retention Period

Discontinuance of the active phase of orthodontic force signals the beginning of alterations in the bone characteristic of the retention period. During this period there is gradual reformation of the normal dense pattern of the alveolar bone by apposition of bone around the bony spicules until they meet, fuse, and gradually remodel. The studies of Oppenbeim indicated that this reformation is slower around teeth held in position during the retention period by a retaining appliance as compared to teeth which remained free during this time. In any event, the final remodeling and the attainment of absolute bone-tooth equilibrium following orthodontic movements involve an extremely slow process, and a breakdown in this process is probably one of the most important contributing factors in cases of orthodontic failure due to relapse during the retention period.

Effect of Deciduous Tooth Movement upon Permanent Tooth Germs

Breitner and Tischler based on their study in young monkeys found that when a deciduous tooth was moved, the associated permanent tooth germ followed this movement.

Whenever a deciduous tooth was moved away from a tooth germ, the permanent tooth germ quickly followed. If a deciduous tooth was moved toward a permanent tooth germ, this germ moved in the same direction as the deciduous tooth.

These studies offered suggestive evidence that the form of the permanent dental arch may be modified by altering the deciduous arch through orthodontic treatment of the deciduous dentition.

Histologic Features

Microscopically there is focal ulceration with formation of granulation tissue with diffuse chronic inflammatory cell infiltration. Epithelium shows hyerkeratosis and acanthosis adjacent to the ulcers.

Treatment consists of medications to relieve the symptoms and teaching proper brushing technique.

Clinical Features

Eosinophilic ulcerations may occur at any age with a significant male predilection. Though common in anteroventral and dorsal surfaces of the tongue, these lesions may also be observed in other sites such as gingiva, palate, and mucobuccal fold. The ulcerations usually persist weeks to months and resemble traumatic ulcers. The center of the lesion is covered by a removable yellow fibropurulent membrane with erythematous borders.

Histologic Features

Eosinophilic ulcerations are similar to simple traumatic ulcerations in histologic pattern and are characterized by a dense and deeply infiltrative lymphoproliferation, showing epitheliotropism and massive eosinophilia. Presence of sheets of lymphocytes and histiocytes along with hyperplasia of the vascular connective tissue causes elevation of the surface ulceration.

Ulceration resulting from trauma permits the ingress of microorganisms, toxins, and foreign proteins into the connective tissue. These substances, in predisposed persons induce a severe inflammatory response resulting from an exaggerated mast cell-eosinophil reaction similar to that noticed in the pathogenesis of bronchial asthma. Degranulation of the mast cells leads to release of eosinophil chemotactic factor of anaphylaxis.

Treatment and Prognosis

Treatment of eosinophilic ulcerations is similar to simple traumatic ulcerations. Even large eosinophilic ulcerations heal rapidly after a biopsy. Though extraction of the involved teeth solves the problem in Riga-Fede disease, the teeth should be retained if they are stable.

Clinical Features

The lesions are usually bilateral and seen along the occlusal line and also on the vestibular surface of the lips. The mucosa appears white and shredded, with areas of redness. Ulceration is common. This condition is more prevalent in females. Factitial gingival injury is characterized by vertical clefting in the free gingiva, exposure of the root, and gingival ulcers.

Histologic Features

There will be extensive areas of hyperkeratosis with keratin projections representing the ragged areas. Chronic inflammatory cell infiltration is seen in the areas of ulceration.

Treatment

Counseling and psychotherapy are the treatment of choice. However an acrylic shield will help to prevent the access of the teeth to lips and cheeks.

Clinical Features

The denture ulcer, one or more, commonly develops within a day or two after the insertion of a new denture. This may be a result of overextension of the flanges, sequestration of spicules of bone under the denture or a roughened or ‘high’ spot on the fitting surface of the denture.

These ulcers are small, painful, irregularly shaped lesions usually covered by a delicate gray necrotic membrane and surrounded by an inflammatory halo. If treatment is not instituted, there sometimes may be beginning of proliferation of tissue around the periphery of the lesion on an inflammatory basis.

Histologic Features

The traumatic ulcer is a nonspecific ulcer and microscopically shows loss of continuity of surface epithelium with a fibrinous exudate covering the exposed connective tissue (Fig. 12-19). The epithelium bordering the ulcer usually demonstrates proliferative activity. There is infiltration of polymorphonuclear leukocytes in the connective tissue, particularly beneath the area of ulceration, although in chronic lesions these may be replaced by lymphocytes and plasma cells. Capillary dilatation and proliferation may also be evident. Fibroblastic activity is sometimes prominent, and macrophages may be present in moderate numbers.

The treatment for the traumatic denture ulcer consists in correction of the underlying cause: relief of the flange, removal of a tiny sequestrum, or relief of high spots. When this is accomplished, the ulcer usually heals promptly.

Clinical Features

The mucosa beneath the denture becomes extremely red, swollen, smooth or granular and painful. Multiple pinpoint foci of hyperemia, usually involving the maxilla, frequently occur. A severe burning sensation is common. The redness of the mucosa is rather sharply outlined and restricted to the tissue actually in contact with the denture.

Treatment of this condition may not be successful. However, Budtz-Jørgensen and Bertram have reported significant therapeutic effects on denture stomatitis by antifungal therapy. Nystatin tablets 500,000 units, were allowed to dissolve in the mouth three times a day for 14 days. Bergendal and Isacsson reported similar results by treating denture stomatitis with nystatin powder placed on the fitting surface of the denture three times a day for 14 days. In addition, when the dentures fit poorly, construction of new appliances and instruction on hygienic care of the dentures aid in correcting the situation. If new dentures are not constructed, the old dentures must be sterilized daily by soaking in a nystatin solution overnight during the treatment period. Rebasing dentures with soft-tissue conditioners is also reported of benefit in addition to nystatin.

Clinical Features

Inflammatory fibrous hyperplasia as a result of denture injury is characterized by the development of elongated rolls of tissue in the mucolabial or mucobuccal fold area into which the denture flange conveniently fits (Figs. 12-20, 12-21). This proliferation of tissue is usually slow in developing and probably is as much a result of the resorption of the alveolar ridge as of the trauma of the loose dentures.

This excess fold of tissue is not usually highly inflamed clinically, although there may be irritation or even ulceration in the base of the fold into which the denture flange fits. The lesion is firm to palpation.

Histologic Features

The hyperplastic mass of tissue is composed of an excessive bulk of fibrous connective tissue covered by a layer of stratified squamous epithelium which may be of normal thickness or show acanthosis (Fig. 12-21). Pseudoepitheliomatous hyperplasia is often found. Hyper-keratosis is frequently present. The connective tissue is composed chiefly of coarse bundles of collagen fibers with few fibroblasts or blood vessels unless there is an active inflammatory reaction present. Such a reaction is frequently seen, however, in the base of the fissure adjoining the denture flange, especially if the tissue is superficially ulcerated.

One additional histologic finding often seen in the surface epithelium of inflammatory fibrous hyperplasia is mucopolysaccharide keratin dystrophy, also referred to as ‘plasma pooling’, first described by Toto. Its occurrence is not confined to inflammatory hyperplasia but may also be found in oral epithelium under a wide variety of other conditions, especially those involving irritated epithelium. This mucopolysaccharide keratin dystrophy consists histologically of homogeneous, eosinophilic pools of material in the superficial spinous layer of epithelium, where it appears to have replaced individual cells. Its significance is not known.

Treatment and Prognosis

Inflammatory fibrous hyper-plasia should he surgically excised, and either new dentures constructed or the old dentures rebased to provide adequate retention. If the denture is replaced or repaired, the lesion should not recur. Complete regression, even after construction of new dentures, will not occur, although subsidence of the inflammatory reaction may produce some clinical improvement of the condition.

Clinical Features

Papillary hyperplasia occurs predominantly in edentulous patients with dentures, but is seen on rare occasions in patients with a full complement of teeth and no prosthetic appliance. In a series of 5,892 dental patients, Guernsey reported an incidence of 2.9% in denture wearers but only 0.2% in nondenture wearers. However, Bhaskar and his associates have stated that approximately 20% of all patients who wear dentures 24 hours a day show papillary hyperplasia, while among all denture wearers, the prevalence is 10%. Ettinger, studying the etiology and incidence of papillary hyperplasia, reported a similar occurrence of 97 affected patients, or 13.9%, in a series of 700 denture wearers. He concluded that constant wearing of the denture was one of the most important factors associated with the condition. When an appliance is present, the site of the lesion corresponds to the denture base, sometimes only to the relief chamber. It may arise at any age in the adult and has no definite sex predilection.

The lesion presents itself as numerous, closely arranged, red, edematous papillary projections, often involving nearly all of the hard palate and imparting to it a warty appearance. The lesions may extend onto the alveolar mucosa, and mandibular alveolar mucosa involvement occasionally occurs. The individual papillae are seldom over a millimeter or two in diameter. The tissue exhibits varying degrees of inflammation, but ulceration is rare (Fig. 12-22).

Histologic Features

The microscopic section of papillomatosis shows numerous, small vertical projections each composed of parakeratotic or sometimes orthokeratotic stratified squamous epithelium and a central core of connective tissue (Fig. 12-23). Pseudoepitheliomatous hyperplasia, in varying degrees, is seen in the vast majority of cases; this is sometimes so severe as to be interpreted by the inexperienced pathologists as epidermoid carcinoma. However, most authorities now agree that true epithelial dysplasia and malignant transformation do not occur in palatal papillomatosis. Relatively severe inflammatory cell infiltration is nearly always present in the connective tissue, as is chronic sialadenitis in the accessory palatal glands. In the latter instance, metaplastic changes in acinar and ductal epithelium may mimic neoplastic transformation.

Treatment and Prognosis

There is no well recognized and accepted course of therapy for this condition. Discontinuing the use of the ill-fitting dentures or construction of new dentures without surgical removal of the excess tissue will generally result in regression of the edema and inflammation, but the papillary hyperplasia persists. Preferably, surgical excision of the lesion prior to new denture construction will return the mouth to a normal state. The use of a tissue conditioner to rebase an old denture often results in some improvement of the lesion, but seldom complete regression unless it is in an early stage.

Etiology and Pathogenesis

The mucous retention phenomenon is a common lesion. Many authorities formerly believed that this type of lesion resulted from obstruction of the duct of a minor or accessory salivary gland, but experimental investigations on mice by Bhaskar and his associates and on rats by Standish and Shafer failed to produce the mucous retention phenomenon by ligation of the submaxillary and sublingual gland ducts. The studies of Bhaskar and coworkers have shown instead that if the salivary duct was severed so that a continuous pooling of saliva occurred in the tissues, a well-demarcated cavity developed which was histologically identical with the natural mucocele.

These investigations appear to indicate that traumatic severance of a salivary duct, such as that produced by biting the lips or cheek or pinching the lip by extraction forceps, precedes the development of the retention phenomenon. It is also possible that a chronic partial obstruction of a salivary duct, in contrast to the acute total obstruction experimentally produced by ligation in mice and rats, may be of etiologic importance. Such a partial obstruction could result from a small piece of intraductal calculus or even from contraction of developing scar connective tissue around a duct after a traumatic injury. Occasional cases of calculus in the ducts of accessory salivary glands, or sialolithiasis (q.v.), have been reported, but are rather uncommon. Thus, mucoceles often have been classified as: (1) an extravasation mucocele, or (2) a retention mucocele (or true retention cyst). The extravasation type is far more common than the retention type.

Clinical Features

The retention phenomenon involving accessory salivary gland structures occurs most frequently on the lower lip, but may also occur on the palate, cheek, tongue (involving the glands of Blandin-Nuhn), and floor of the mouth. In the series of cases reported by Standish and Shafer, nearly 45% of the 97 mucoceles occurred on the lower lip. No cases were found in their series on the upper lip. In addition, there was no predilection for any age group, the lesions being rather equally divided among all decades of life, from lesions present at birth to the ninth decade. An equal distribution in occurrence between males and females was also noted in their study. In a study of 125 cases of mucocele, Robinson and Hjørting-Hansen reported similar findings except for the age predilection. They found that nearly 65% of their cases occurred within the first three decades of life. Ramanathan and his coworkers, in their series of 250 cases of mucoceles, found that nearly 85% occurred in the same time span.

Clinically, the lesion may lie fairly deep in the tissue or be exceptionally superficial and depending upon the location, will present a variable clinical appearance (Fig. 12-24). The superficial lesion appears as a raised, circumscribed vesicle, several millimeters to a centimeter or more in diameter, with a bluish, translucent cast. The deeper lesion is manifested also as a swelling but because of the thickness of the overlying tissue, the color and surface appearance are those of normal mucosa.

It is interesting and significant that the mucous retention phenomenon is restricted almost entirely to the lower lip, seldom found on the upper lip, while accessory salivary gland neoplasms of the lips are almost universally found on the upper lip and only rarely on the lower lip. This could imply that trauma plays no role in the development of salivary gland tumors in this location.

The mucous retention phenomenon often arises within a few days, reaches a certain size and may persist as such for months unless treated. If the contents of the cyst are liberated, they usually are found to consist of a thick, mucinous material. Some lesions regress and enlarge periodically and may disappear after traumatic injury which results in their evacuation. They almost invariably recur, however.

Histologic Features

The majority of mucoceles, being of the extravasation type, consist of a circumscribed cavity in the connective tissue and submucosa, producing an obvious elevation of the mucosa with thinning of the epithelium as though it were stretched (Fig. 12-25). The cavity itself is not lined by epithelium and is, therefore, not a true cyst. Instead, its wall is made up of a lining of compressed fibrous connective tissue and fibroblasts. Sometimes these cells may be mistaken for flattened epithelial cells. Not uncommonly the connective tissue wall is essentially granulation tissue, but in any event it usually shows infiltration by abundant numbers of polymorphonuclear leukocytes, lymphocytes, and plasma cells. The lumen of the cyst like cavity is filled with an eosinophilic coagulum containing variable numbers of cells, chiefly leukocytes and mononuclear phagocytes.

Occasional mucoceles demonstrate an intact, flattened epithelial lining. It is probable that this simply represents the portion of the excretory duct bordering the line of severance, if severance is actually the manner in which these lesions develop. The flattened epithelial lining has been referred to as epithelium of the ‘feeder duct’. In other instances, the epithelium-lined mucocele represents a lesion of the retention type.

The salivary gland, acini which lie adjacent to the area of the mucocele and are associated with the involved duct often show alterations. These may consist of interstitial inflammation or sialadenitis, dilatation of intralobular and interlobular ducts with collection of mucus, and breakdown of individual acinar mucous cells resulting in the formation of tiny areas of pooled mucus.

Treatment and Prognosis

Treatment of the mucous retention phenomenon is excision. If the lesion is simply incised, its contents will be evacuated, but it will be rapidly filled again as soon as the incision heals. There is occasional recurrence after excision, but this possibility is less likely if the associated salivary gland acini are removed also.

Clinical Features

This lesion, which is rare compared to the usual mucocele, develops as a slowly enlarging painless mass on one side of the floor of the mouth (Fig. 12-26).The tongue may be elevated and when it is large it may hide the salivary gland. Since the lesion is usually a deep-seated one, the overlying mucosa is normal in appearance. If the lesion is superficial, the mucosa may have a translucent bluish color. A rare, plunging, suprahyoid type which has herniated through the mylohyoid muscle is also described. A thorough review of the literature on the plunging or cervical ranula has been reported by van den Akker and his associates, who also described four typical cases.

Histologic Features

The microscopic appearance is similar to that of the smaller mucocele except that a definite epithelial lining is sometimes present. Because of this finding, most investigators consider the ranula to be a true retention cyst, probably occurring as a partial blockade phenomenon, although a salivary duct stone is often not demonstrable.

Treatment and Prognosis

The treatment is either marsupialization or more often excision of the entire sublingual gland. Occasionally the lesion recurs if the entire sublingual gland or other gland causing them is not excised with the lesion.

Clinical Features

Most retention cysts of the maxillary sinus are completely asymptomatic and are discovered only during routine radiographic examination of the jaws. Occasionally, discomfort in the cheek or maxilla may be present. Pain and soreness of the face and teeth and numbness of the upper lip were described by Wright in about 10% of his series of 78 cases. Buccal expansion of the maxillary antrum has also been reported. There is no clear-cut age or sex predilection for occurrence of the lesion. Additional series of cases have been reported by Casamassimo and Lilly (73 cases in 4,546 patients, or 1.6%), Myall and his coworkers (73 cases in 1,469 patients, or 5.1%), and Halstead (45 cases in 2,325 patients, or 1.9%).

Radiographic Features

In the dental periapical radiograph, the lesion appears as a well-defined, homogeneous, dome-shaped or hemispheric radiopacity, varying in size from a tiny lesion to one completely filling the antrum, arising from the floor of the antrum and superimposed on it (Fig. 12-27). This radiopacity appears as a soft tissue mass rather than a calcified area, so that medial and lateral landmarks can generally be visualized through the lesion. In some instances the lesion appears more radiolucent than radiopaque. In the various reported series, between 10 and 20% of the cases have occurred bilaterally.

Histologic Features

Some of these retention cysts are analogous to the mucous retention phenomenon in as much as they consist of the accumulation of fluid within connective tissue spaces and have no definite lining. This type has sometimes been referred to as a non-secretory cyst. In other instances the lesion may be lined by a respiratory type of epithelium, and this has sometimes been described as the secretory type of antral cyst. In either case inflammatory cell infiltration in the connective tissue wall of the specimen is common.

Treatment

The majority of these cysts either persist unchanged or disappear spontaneously within a relatively short period, and for this reason it has been suggested that no treatment is necessary.

Differential Diagnosis

Care must he taken to differentiate this lesion from apical periodontal cysts of teeth in close association with the maxillary sinus, from fibro-osteomas of this area, and especially from the surgical ciliated cyst of the maxilla. Although etiologically different from the last lesion, the antral mucocele may be related to it pathogenetically.

Clinical Features

Many patients with sialolithiasis involving a duct of a major salivary gland complain of moderately severe pain, particularly just before, during and after meals, owing to psychic stimulation of salivary flow, associated with swelling of the salivary gland. The occlusion of the duct prevents the free flow of saliva, and this stagnation or accumulation of saliva under pressure produces the pain and swelling. In some instances this swelling is diffused and simulates a cellulitis. Occasionally the stone presents no remarkable symptoms, and the only evidence may be a firm mass palpable in the duct or gland. In some cases large numbers of individual small stones may be found occluding the duct system.

Stones, particularly in the more peripheral portion of the duct, may often be palpated if they are of sufficient size. They may also be demonstrated on the dental radiograph when appropriately located, particularly by the use of sialography (Fig. 12-28A). However 20% of the parotid and 40% of the submandibular stones are not radiopaque. Sialography is the retrograde injection of a radiopaque material into the duct system of a salivary gland and the study of its distribution by radiographs.

Sialolithiasis may occur at any age, but is most common in middle-aged adults. Wakely reported that the occurrence of sialolithiasis in a large group of cases shows the following distribution: submandibular gland and duct, 64%; parotid gland and duct, 20%; and sublingual gland and duct, 16%. In a series of 180 cases reported by Levy and his associates, the gland distribution was 80%, 19%, and 1%, respectively. The common involvement of the submandibular gland and duct is thought to be due to the tenacity of the submandibular saliva, which, because of its high mucin content, adheres to any foreign particle. The submandibular duct is also long and irregular in its course.

Sialolithiasis involving ducts of the minor or intraoral accessory salivary glands sometimes is also seen. The majority of these sialoliths are found in the upper lip, with only slightly fewer in the buccal mucosa, together accounting for nearly 90% of all cases. Occasional cases are reported in the buccal sulcus, lower lip, palate, and tongue. They usually present as solitary, firm, freely movable, small masses or nodules, and may or may not be symptomatic.

Chemical and Physical Features

The sialolith may be round, ovoid, or elongated. It may measure just a few millimeters or 2 cm or more in diameter. The involved duct may contain a single stone or many stones. The surface of the calculi is rough, which may cause the duct lining to undergo squamous metaplasia. They are usually yellow and occasionally white or yellowish-brown in colour. It consists mainly of calcium phosphates and smaller amounts of calcium carbonates, organic materials, and water. Submandibular stones tend to be larger than those of the parotid or other minor glands.

Histologic Features

Microscopically the calcified mass exhibits concentric laminations (Fig 12-28B) around a central nidus of amorphous debris. The lamellated structure of the calculi is the result of successive deposition of inorganic and organic material. Periductal inflammation is also seen. The ductal obstruction frequently is associated with an acute or chronic sialadenitis of the feeding gland.

Treatment and Prognosis

Small calculi may sometimes be removed by manipulation or increasing the salivation by sucking a lemon, leading to expulsion of the stone. An intravenous antibiotic is given for bacterial infection due to persistent obstruction of the duct. The larger stones almost always require surgical removal. If they are present near or in the substance of the gland itself, particularly if multiple, surgical extirpation of the gland may be necessary. Piezoelectric shock wave lithotropsy may be an alternative to surgical removal. The solitary sialolith does not usually recur, although occasional cases have presented chronic multiple recurrences.

Clinical Features

The antrolith may occur at any age in either sex. There may be a complete absence of symptoms, although some cases are marked by pain, sinusitis, nasal obstruction, and/or foul discharge, and epistaxis. Some cases, according to Blaschke and Brady, are discovered accidentally during radiographic examination in which an opaque mass is evident in the sinus. At times Aspergillus species served as a central fungus nidus associated with long-standing sinusitis, and poor sinus drainage resulting in the formation of a sinus stone.

Treatment

The antrolith should be surgically removed.

Effects of Radiation on Oral and Paraoral Tissues

Radiation effects are dependent upon a great number of factors such as the source of the radiation, the total amount of radiation administered, the period of time over which the radiation was administered (fractionation), the type of filtration used and the total area of tissue irradiated. The changes to be described here are those frequently seen after delivery of local therapeutic doses of X-ray radiation in the treatment of neoplasms about the head and neck. They are in no way related to the use of the diagnostic X-ray machine. No attempt will be made to describe the effect of total body radiation, such as those occurring after detonation of the various nuclear bombs, because of the lack of significant clinical application of such information.

However, adult patients with acute leukemia in relapse, whose disease has become refractory to all known chemo-therapeutic drugs, may receive bone marrow transplantation following total body radiation in an attempt to prolong their lives. The oral changes in 35 patients following 850–950 rads of total body X-ray radiation were detailed by Dreizen and his associates in 1979. Almost every patient exhibited bilateral parotitis, partial xerostomia, and oral mucositis following total body radiation. The parotitis resembled mumps that resolved spontaneously in 24–48 hours. Saliva production during the first week after radiation was noticeably reduced in amount and was thicker, ropier, and more mucoid than usual. The mucositis, which lasted two to three weeks, began as swelling, soreness, and whitening of the oral mucosa. Within 48–72 hours, the lips, tongue, and/or entire oral cavity showed an intense reddening of the oral mucosa. Pain and denudation accompanied the mucositis. After two or three weeks there was a whitening of the oral mucosa, which has been attributed to impaired mitotic activity and prolonged retention of the superficial epithelial cells, leading to an abnormally high degree of keratinization. Palliation of the transient radiation mucositis was achieved with warm salt water or sodium bicarbonate mouthrinses.

Evidence is accumulating that cobalt-60 radiation therapy, as contrasted with conventional orthovoltage radiation, may have significant skin- and bone-sparing qualities. Thus, this technique may reduce the incidence of radiation complications so frequently seen in the past.

Effects on Skin

The effects of heavy therapeutic doses of X-ray radiation on the skin are well documented, although variable among patients. Erythema is the earliest visible reaction and begins within a few days after irradiation. The original erythema fades quickly, only to reappear within two to four weeks. The secondary erythema fades slowly; often leaving the skin permanently pigmented a light tan shade. After heavy irradiation the secondary erythema may be accompanied by edema with desquamation of epithelial cells resulting in denudation of the surface. Re-epithelialization occurs in 10–14 days. These early effects are caused by direct injury of the radiated cells and tissues, while the later effects are brought about chiefly by changes in the vascular bed and in the intercellular material.

Alterations in the sebaceous gland activity, evidenced by a reduction in secretion with dryness of the skin, may occur within a week after the beginning of irradiation. The hair follicles are also sensitive to this type of radiation, and epilation, either temporary or permanent, may be produced. The sweat glands are similarly disturbed so that their absence of secretion contributes to the dryness and scaling of the skin.

Eventually the epithelium becomes thin and atrophic, and the superficial blood vessels become telangiectatic or occluded. The telangiectasia may persist for months or even years as evidence of the effect of X-rays. Other evidence of vascular damage includes thickening of the intima and, in some cases, thrombosis. Some veins and arteries show subintimal fibrosis with thickening of the wall at the expense of the lumen. Endophlebitis and phlebosclerosis may be particularly evident.

Effects on Oral Mucosa

The changes occurring in the oral mucosa after X-ray radiation are essentially the same as those in the skin and are related to the dose and the duration of therapy. The erythema may develop at a somewhat lower dose of X-ray, and the mucositis which occurs after therapeutic radiation is evoked somewhat earlier than the analogous dermatitis (Fig. 12-29).

Dreizen and his coworkers studied the effects of radiotherapy for oral cancer on the oral mucosa. They found that the mucosa in the path of radiation first appeared hyperemic and edematous. As treatment continued, the mucosa became denuded, ulcerated, and covered with a fibrinous exudate. Great discomfort, which was intensified by contact with coarse or highly seasoned foods, was commonly present. The mucositis persisted throughout radiotherapy and for several weeks thereafter. Unless secondary infection occurred, spontaneous remission followed termination of the radiation therapy. In many patients, a lidocaine mouthrinse before mealtimes was necessary to produce topical anesthesia so that eating was possible. When pain and dysphasia could not be controlled with local anesthetics and analgesics, nasogastric tube feeding was necessary.

Patients undergoing radiotherapy for oral cancer also quickly lost their sense of taste, probably because of damage to the microvilli and outer surface of the taste cells. The effect was usually transitory, and taste acuity was restored within 60–120 days after completion of the radiotherapy.

Effects on Salivary Glands

Xerostomia, or dryness of the mouth, is one of the earliest and most universal of complaints of patients receiving therapeutic radiation about the head and neck. Alterations in the salivary glands, characterized by diminution or even complete loss of secretion, may occur within a week or two after the beginning of radiation. It is interesting that the morphologic changes do not particularly mirror the physiologic changes which occur. There is some obvious damage of the acinar cells, chiefly a decrease in the number of secretory granules present, with congestion, edema, and inflammatory cell infiltration of the interstitial connective tissue. There are no remarkable changes in the ducts of the salivary glands.

One interesting feature of acute post radiation sialadenitis is the elevation of serum and urinary amylase, the source of this amylase being the salivary glands. This is one of the few biochemical changes that occur early and consistently following irradiation. Kashima and his associates have discussed this finding, as well as other clinical and histopathologic features of post radiation sialadenitis, concluding that direct exposure of the salivary glands is necessary to provoke this change and that the serum amylase response is related to the dose of irradiation.

The loss of secretion may be a permanent sequelae of the radiation, or there may be a gradual return of salivation, usually only after many months.

Effects on Teeth

Erupted teeth are often affected in patients who have received X-ray radiation about the head and neck, but the damage may not appear for several years after the radiation. The most common manifestation of the injury is a peculiar destruction of tooth substance, resembling dental caries and sometimes called ‘radiation caries’, which often begins at the cervical area of the teeth. The lesion resembles a demineralization more than it does true caries because of its pattern or the manner in which it sweeps across the tooth, sometimes causing amputation of the tooth crown at its neck. Teeth often seem brittle, and pieces of the enamel may fracture away from the tooth (Fig. 12-30).

The primary cause of the condition lies in alterations of the saliva induced by either direct or indirect radiation of the salivary glands. Although physical and chemical changes in the saliva following salivary gland irradiation have been postulated, there is no evidence for such changes other than the direct observation that the saliva often becomes somewhat thicker and more tenacious after irradiation. The xerostomia of varying degrees certainly favors the collection of debris on the teeth and ensuing caries. Radiation induced xerostomia in humans produced pronounced shifts in the oral microbial population, with cariogenic microorganisms gaining prominence at the expense of noncariogenic ones. These changes occurred prior to the onset of clinical caries and were irrespective of the use of a topical fluoride gel as a caries preventive measure.

Close cooperation between the radiotherapist, the dentist, and the patient is essential in promoting oral care for these patients. As Dreizen and his associates pointed out, xerostomia also deprives the teeth of an important natural defense against dental decay. There is a sharp decrease in the total daily output of caries-protective salivary electrolytes and immunoproteins. Patients with xerostomia change their eating habits to include frequent, nondetergent, and high carbohydrate meals. The microbial, chemical, immunologic, and dietary changes produce an enormous increase in the caries challenge.

Regardless of the patient’s previous caries history, the development of xerostomia is inevitably followed by rampant dental decay unless stringent protective steps are taken. Cariogenesis is so greatly accelerated that frank lesions may appear within three months after radiotherapy. However, the ravages of dental decay in the radiated patient can be almost completely prevented with one daily application of a 1% sodium fluoride gel containing a red, plaque-disclosing dye. This protocol was developed by Daly and Drane in 1972. The gel is applied for at least five minutes by means of custom fabricated flexible plastic carriers. When the carriers are removed and the gel is rinsed off, the plaque is stained red and can be removed by brushing and flossing. To be maximally effective, the program must be instituted at the beginning of radiotherapy and continued every day. Such a regimen can also arrest caries caused by xerostomia in previously unprotected patients. Because of the ever-present risk of caries in xerostomic patients, only diligent, lifelong cooperation will assure prevention.

Developing teeth are also particularly sensitive to X-ray radiation. Leist and Smith demonstrated that irradiation of developing teeth in rats resulted in a disorganization of the odontoblasts and the formation of atypical dentin. Ameloblasts appear to be considerably more resistant to radiation than odontoblasts, although Burstone demonstrated in mice that, after sufficient radiation there was cessation of ameloblastic histogenesis and metaplasia of ameloblasts to a less differentiated type of cell. Similar interference with tooth formation in rats has been reported by English and his coworkers.

Radiation of developing teeth in human beings sometimes occurs, and if it is at a sufficiently young age, manifestations of the injury may be obvious. Such radiation is usually administered for the treatment of a tumor about the head and neck, frequently a hemangioma. Depending upon the age of the patient at the time of the irradiation, there may be complete cessation of odontogenesis resulting in anodontia in the involved area or simply a stunting of the teeth (Fig. 12-31) have been cited by Carl and Wood.

Effects on Bone

Bone itself is relatively resistant to X-ray radiation, although osteoblasts are sensitive. If the radiation has been sufficiently intense, the normal balance between bone formation and bone resorption is disturbed; general bone vitality is decreased, and localized osteoporosis may result.

The greatest clinical significance of bone which has been irradiated lies in the inability of this bone to react in the normal fashion to infection. This is related, at least in part, to the damage of the vascular bed with subsequent disturbance of the typical inflammatory response. There is little actual danger to the patient except in a situation in which infection may enter the bone with little difficulty and spread widely. This may occur in the maxilla and mandible.

An experimental study of the effects of radiation on extraction wound healing in rats has been reported by Stein and coworkers. They found that when radiation shortly followed tooth extraction, there was retardation of surface closure of the wound, leaving an open pathway for tissue infection. The healing response was poor and slow. As the interval between tooth extraction and radiation was increased, impairment of healing decreased. In general, the longer the interval between tooth extraction and initiation of radiation, the less possibility is there of healing complications.

Effect on Soft Tissue

When directed at soft tissue, laser radiation has the ability to produce nonspecific ulceration of the epithelium with acute purulent inflammation. This finding was reported by Taylor and his associates when laser radiation was directed at the tongue of experimental animals.

Clinical Features

The emphysema manifests itself as a unilateral swelling of the tissues of the face and/or neck which occurs very rapidly and is generally somewhat painful, particularly during the first few days (Fig. 12-34). Not infrequently, the patient will complain of a ‘bubbling’ sensation when palpating this tissue and of difficulty in breathing. The facial enlargement is often confused with an angioedema, but it can be differentiated by identifying crepitus within the swelling. Spread into the mediastinum results in dysphagia, or dyspnea. In mediastinal involvement crepitus synchronous with the heartbeat (Hamman’s crunch) is heard on cardiac auscultation.

Pneumoparotid appears as a unilateral enlargement of the parotid with demonstration of crepitus on palpation. Frothy air-filled saliva is produced by the parotid duct rather than the clear, water-like secretion.

Treatment and Prognosis

Unfortunately, venous air embolism is an unusual but often fatal complication of this condition. For example, Longenecker has reported that, of six cases of venous air embolism occurring during head and neck surgery, five terminated fatally. If the entrance of air into the venous circulation can be recognized promptly, resuscitation may prevent death. A second complicating factor is the possibility of bacterial infection in the emphysematous connective tissue, microorganisms being carried into the tissues with the air. In such instances, broad-spectrum antibiotic coverage is recommended. Aside from this, there is no particular treatment indicated and the condition will generally resolve within a week.

The treatment for pneumoparotid consists mainly of altering the inciting event to prevent air from entering the parotid duct. Acute symptoms can be treated with antibiotics, hydration, massages, sialagogues, and compresses.

Aspirin (Acetylsalicylic Acid)

Aspirin tablets are used mistakenly by many people as a local obtundent, especially for the relief of toothache. It is also available in a powder form. Although effective if used systemically, they are particularly harmful to the oral mucosa if applied locally. The usual mode of local use is to place the tablet against the offending tooth, allowing the cheek or lip to hold it in position, and to let it dissolve slowly. Within a few minutes a burning sensation of the mucosa will be noted, and the surface becomes blanched or whitened in appearance (Fig. 12-35). The caustic action of the drug causes separation and sloughing of the epithelium and frequently bleeding, especially if the area is traumatized. The healing of the painful ‘aspirin burn’ usually takes a week or more.

Endodontic Materials

Soft tissue damage resulting in deep spread of inflammation and necrosis may occur due to the usage of some endodontic materials or their injection into the hard tissue. For instance paraformaldehyde is used to devitalize the inflamed pulp. This caustic agent may leak from the pulp chamber into the surrounding tissues and causes necrosis of the gingiva and bone.

Sodium hypochlorite and hydrogen peroxide produces similar damage when injected beyond the apex.

Sodium hypochlorite (NaOCl) is commonly used as root canal irrigant. Due to its efficacy against pathogenic organisms and pulp digestion it is considered to be the medicament of choice. It is found to be sporicidal and virucidal and shows far greater tissue dissolving effects on necrotic than on vital tissues as well as the organic components of the smear layer. Although considered safe, it may cause severe tissue damage if come in contact with the tissues or extruded beyond the apex. On contact with vital tissue, it causes hemolysis, ulceration, facial nerve weakness, and necrosis, inhibits neutrophil migration, and damages endothelial cells and fibroblasts. Inadvertent injection of NaOCl solution into periapical tissues leads to emphysema, caused by oxygen liberation into the tissues, permanent facial and trigeminal nerve weakness and allergic reactions. Bowden, Ethunandan, and Brennan have reported a case of life-threatening airway obstruction secondary to hypochlorite extrusion during root canal treatment.

Gutta-percha is a biologically inert latex material used to obturate, or fill the empty space inside the root of a tooth during endodontic treatment. It is used along with zinc oxide eugenol to attain apical seal. Gutta-percha points extruded past. The apices result in infective periapical periodontitis caused by the transport of bacteria beyond the apex and an incomplete cleansing and foreign body reactions.

Hydrogen peroxide is used commonly in varying concentrations in many branches of dentistry. It is a caustic agent. Upon contact it burn tissues and release toxic free radicals, perhydroxyl anion, or both. It should be handled with care in high concentrations, since it is thermodynamically unstable and may explode if not refrigerated or stored in a dark container.

30–35% hydrogen peroxide (superoxal) is used along with heat (thermocatalytic) for bleaching. This thermocatalytic process damages the tooth by causing irritation to the cementum and periodontal ligament leading to cervical root resorption.

Sodium perborate has been widely used as a mouthwash, bleaching agent, and in dentifrices because of its supposed therapeutic effect on gingival disease. Clinical studies reveal, however, that the compound may produce an erythema of the oral mucosa which may even progress to sloughing of the tissues. In some instances the inflammation was aggravated, and edema and ulceration of mucosa frequently occurred. The lesions healed spontaneously with cessation of treatment.

Carbamide peroxide is used as a component in bleaching preparation. These preparations were reported to be associated with varying degrees of damage to the teeth and the surrounding structures if not used cautiously.

Phenol is widely used in dentistry as a cavity sterilizing agent as well as a cauterizing agent in various procedures. It is extremely caustic and if used carelessly may produce severe painful burns of the oral mucosa and skin which heal slowly (Fig. 12-36).

Silver nitrate is also used extensively in dentistry as a cavity sterilizing agent, topically as a caries-preventive agent and as a chemical cautery. Injudicious or overzealous use may produce painful burns of the oral mucous membranes.

Trichloroacetic acid used as a cauterizing agent, particularly to cauterize gingival tissue when preparing a proximal or gingival cavity, placing a band or taking an impression of a cavity. Because of its extremely caustic nature, this acid may cause serious injury to the mucosa or skin if it is used carelessly.

Volatile oils such as oil of cloves, oil of wintergreen, and eucalyptus oil are used in dentistry and can produce mild burns of the mucous membranes.

Oral Manifestations

These include intense inflammation of oral mucous membranes, and severe gingivitis. The tissues may be painful. Local contact with arsenic trioxide often produces ulceration. Systemic arsenic poisoning also produces excessive salivation.

Bisphosphonate a potent antiresorptive agent, used in the management of benign and malignant diseases involving excessive bone resorption, such as bone lesions of multiple myeloma and metastatic bone diseases. They act by blocking the dissolution of hydroxyapatite, inhibiting differentiation of bone marrow precursors into osteoclasts, and inhibiting the osteoclast function. It causes osteonecrosis in many patients. The incidence of bisphosphonate associated osteonecrosis has been increased recently, and most of the cases involve nitrogen-containing bisphosphonates, mainly pamidronate and zolendronate. Osteonecrosis of the jaw probably results from the inability of hypodynamic and hypovascular bone to meet an increased demand for repair and remodeling. According to some authors, the predilection for this location may be attributed to the fact that the jaws are the only bone structures submitted to continuous trauma and masticatory stress with exposure to the environment and to oral microorganisms. Dental extractions have been identified as a predisposing factor for osteonecrosis in many cases; but cases of ‘spontaneous’ exposures and necrosis of the alveolar bone have also been reported.

Hellstein et al, reported 28 suspected cases of osteonecrosis of the jaw and discussed the nomenclature, the clinical and radiographic findings, as well as the main modalities of therapy and prevention. They suggested the term bisphosphonate osteochemonecrosis or bis-phossy jaw, since the features of bisphosphonate-associated osteonecrosis are similar to those found in phossy jaw, the historical occupational osteonecrosis of the jaw caused by exposure to white phosphorus during the manufacture of matches.

Treatment and Prognosis

There is no effective treatment for this condition. Most of the lesions have not responded well to surgical intervention, antibiotic therapy, hyperbaric oxygen therapy, or to the topical use of mouthrinses. Current conservative approach is sequential removal of sequestrum. Removal of the bone sequestrum with minimal epithelial manipulation with topical and systemic antibiotics seem to be the treatment modality of choice.

Bismuth was formerly used widely in the treatment of syphilis, but it has been replaced in recent years by the antibiotics. The use of this metal is still common in treating certain dermatologic disorders as well as various other diseases, so that oral signs are still sometimes seen.

Oral Manifestations

Bismuth pigmentation of the oral mucosa, particularly of the gingiva and buccal mucosa, is the most common oral feature of bismuth therapy and is reported to occur in a high proportion of patients receiving preparations containing the metal.

The pigmentation appears as a ‘bismuth line’, a thin blue-black line in the marginal gingiva which is sometimes confined to the gingival papilla (Fig. 12-39). There may also be the same type of pigmentation of the buccal mucosa, the lips, the ventral surface of the tongue, or in any localized area of inflammation such as around partially erupted third molars or around the periphery of an ulcer as an anachoretic phenomenon (Fig. 12-40).

This pigment represents precipitated granules of bismuth sulfide produced by the action of hydrogen sulfide on the bismuth compound in the tissues. The hydrogen sulfide is formed through bacterial degradation of organic material or food debris and is most common in sites of food retention. The bismuth line occurs in the majority of patients receiving prolonged bismuth treatment and is more frequent in unclean mouths. Patients receiving this metal also complain occasionally of a burning sensation of the mucosa and a metallic taste in the mouth.

Histologic Features

The granules of the sulfide are seen in the tissue section as small, irregular black collections of pigment, sometimes perivascular in location, but other times diffuse without apparent arrangement (Fig. 12-41). The material may be present in endothelial cells or in mononuclear phagocytes in the tissue, but it usually is in the intercellular tissue. It provokes no foreign body response and may be present even in the absence of inflammation.

Treatment and Prognosis

There is no specific treatment for the bismuth line. Once it is established, although it reportedly can be bleached by concentrated hydrogen peroxide. Its prevention by scrupulous oral hygiene during therapy is recommended. The prognosis of the condition is good. If untreated, the line will gradually disappear over a long period of time if use of the bismuth compound is discontinued.

Oral Manifestations

Gingival hyperplasia may begin as early as two weeks after dilantin therapy has been instituted, although usually it takes two to three months. The first change noted is a painless increase in the size of the gingiva, starting with the enlargement of one or two interdental papillae. The surface of the gingiva shows an increased stippling and finally a cauliflower, warty, or pebbled surface. As enlargement increases, the gingival tissue becomes lobulated, and clefts remain between each enlarged gingiva in many cases (Fig. 12-42). Palpation reveals that the tissue is dense, resilient and insensitive. It shows little tendency to bleed.

The hyperplasia of oral mucosa is almost entirely confined to the gingival tissues surrounding the teeth. In cases in which a patient is dentulous, but has a few edentulous areas, the gingival tissues around the teeth may show extreme hyperplasia, while the edentulous regions are generally normal in appearance. On rare occasions hyperplasia may occur in localities apart from the gingiva, such as the palate in patients wearing a prosthetic appliance, a probable source of chronic irritation (Fig. 12-43).

Histologic Features

Microscopic study of the gingival tissue reveals a suggestive but not pathognomonic appearance. The stratified squamous epithelium covering the tissue is thick and has a thin keratinized layer. The rete ridges are extremely long and thin, sometimes called ‘test-tube’ pegs, with considerable confluence, but mitotic figures are seldom seen. The bulk of the tissue is made up of large bundles of collagen fibers interspersed with fibroblasts and fibrocytes (Fig. 12-44). Vascularity is not a prominent feature of the lesion. If chronic inflammation is superimposed on this hyperplasia, plasma cells and leukocytes will be found.

Treatment and Prognosis

No treatment is necessary until the enlargement becomes esthetically objectionable. If the hyperplasia interferes with function, surgical excision is recommended, but the hyperplasia will often recur. Discontinuing use of the drug will result in a gradual diminution of the bulk of the gingiva. Most patients, however, prefer to continue use of the drug and suffer with the hyperplasia rather than resort to some other, less effective drug for the prevention of the epileptic seizures.

Clinical Features

Not seen in all patients receiving cyclosporine. Appearance of gingival overgrowth is similar to that induced by dilantin. Presence of local factors aggravates the extent of the lesion.

Clinical Features

Lead intoxication is manifested by serious gastrointestinal disturbances which include nausea, vomiting, colic, and constipation. A peripheral neuritis also develops which may produce the characteristic wrist-drop or foot-drop. Encephalitis may also occur. Blood changes are those of a hypochromic anemia with basophilic stippling of the red blood cells. Skeletal changes due to deposition of lead in growing bone occur in children and are demonstrable on the radiograph.

Oral Manifestations

The formation of a ‘lead line’ similar to the ‘bismuth line’ occurs in lead poisoning. This gray or bluish black line of sulfide pigmentation occurs in the gingiva, but is somewhat more diffuse than that of bismuth. It is also found occasionally in other areas of the oral cavity. Ulcerative stomatitis is an additional reported finding.

Excessive salivation and a metallic taste are also common complaints in this condition, as is swelling of the salivary glands. It is reported by Altshuller and his associates that lead is deposited in the deciduous teeth of children suffering from lead poisoning, and that those teeth may serve as an index of the body burden of lead.

Treatment and Prognosis

Treatment of the oral lesions is secondary to systemic treatment, and the prognosis depends upon the systemic condition of the patient.

Clinical Features

Chronic mercurialism is characterized by gastric disturbances, diarrhea, excitability, insomnia, headache, and mental depression. The patients frequently have fine tremors of the fingers and limbs as well as of the lips and tongue. In addition, a desquamative dermatitis occurs in some persons. Nephritis is common in acute mercurial poisoning, but does not occur in severe form in the chronic type.

Oral Manifestations

The oral cavity suffers seriously in mercurialism and evidences numerous characteristic but not necessarily pathognomonic signs and symptoms. There is a remarkably increased flow of saliva (ptyalism), and a metallic taste in the mouth due to excretion of mercury in the saliva. The salivary glands may be swollen, and the tongue is also sometimes enlarged and painful. Hyperemia and swelling of the gingiva are occasionally seen.

Ulcerations on the gingiva, palate, and tongue are common. In severe cases pigmentation of the gingiva similar to the bismuth and lead lines may occur as a result of deposition of the dark sulfide compound. Loosening of the teeth, even leading to exfoliation, has been reported.

A toxic reaction from absorption of mercury in dental amalgam has heen reported on a number of occasions. Frykholm, after a thorough review of the literature and numerous studies on the absorption and excretion of mercury, concluded that the amount of estimated exposure to mercury from dental amalgam is not sufficient to cause mercury poisoning in the conventional sense. Nevertheless this exposure may suffice to bring about allergic manifestations in patients sensitive to the mercury, as in the case reported by Fernström and his associates.

Treatment and Prognosis

The treatment of the oral lesions in chronic mercurialism is supportive only and is secondary to the treatment of the poisoning itself. The prognosis is usually good, although severe periodontal destruction and loss of teeth may occur.

Clinical Features

Acrodynia occurs most frequently in young infants before the age of two years, although children are occasionally affected up to the age of five or six years. The skin, particularly of the hands, feet, nose, ears, and cheeks, becomes red or pink and has a cold, clammy feeling. The appearance has been described as resembling raw beef. The skin over the affected areas peels frequently during the course of the disease. The patients also have a maculopapular rash which is extremely pruritic. Severe sweating is an almost constant feature of acrodynia. Other features are a state of extreme irritability, photophobia with lacrimation, muscular weakness, tachycardia, hypertension, insomnia, gastrointestinal upset, and stomatitis. The children will frequently tear their hair out in patches (Fig. 12-45).

The excretion of mercury from the body appears to be a variable phenomenon. For this reason the recovery of unusual amounts of mercury from the urine is not always possible.

Oral Manifestations

Patients with acrodynia exhibit profuse salivation and often much ‘dribbling.’ The gingiva becomes extremely sensitive or painful and may exhibit ulcerations. Bruxism is a common finding and loosening and premature shedding of teeth often occurs; many times the child will extract loose teeth with his/her fingers. Mastication is difficult because of the pain.

Treatment and Prognosis

It is crucial to identify and remove the source of mercury. Immediate chelation therapy is the standard of care for a patient showing symptoms of severe mercury poisoning. The administration of dimercaprol, D-pencillamine, or DMSA, 2,3-dimercapto-1-propanesulfonic acid has proved successful in most cases unless the disease is of long duration. Some of the toxic effects of mercury are in some cases partially or wholly reversible. However, heavy or prolonged exposure can do irreversible damage, particularly in fetuses, infants, and young children.

Clinical Features

Amalgam tattoo appears as macules, or rarely, as slightly raised black, blue, or gray lesion. The most common locations for amalgam tattoos were gingiva, buccal mucosa, and alveolar mucosa. This tattoo has frequently been mistaken for a melanin-pigmented lesion, and in some cases biopsy is necessary to differentiate if the amalgam fragments are too small or diffuse to be visible on the dental radiograph. When the amalgam fragments are embedded within bone, they may be mistaken for a variety of other foreign bodies (Fig. 12-46).

Histologic Features

Microscopically, the dental amalgam fragments frequently show no tissue reaction to their presence, even no inflammatory response (Fig. 12-47). However, in 38% of the cases there was a chronic inflammatory response, usually manifesting as a foreign body granuloma with either foreign body giant cells or Langhans giant cells. In 17% of the cases there was a macrophagic reaction of some type, with or without a chronic inflammatory cell response.

The amalgam fragments appear as black or olive-brown granules or even as macroscopic pieces of material which can be seen plainly in the paraffin-embedded specimen as silver-gray flecks in the tissue. These granules are prominently arranged in a linear fashion along collagen fibers and around blood vessels. In addition, they are found around nerve sheaths and striated muscle fibers and along the basement membrane of mucosal epithelium.

Harrison and his associates have studied these tattoos by electron microscope and electron probe analysis and found that the original mercury-silver-tin amalgam undergoes eventual corrosion, leaving chiefly silver in the extracellular sites.

Clinical Features

The teeth affected by tetracycline appear to have a yellowish or brownish-gray discoloration which is most pronounced at the time of eruption of the teeth. This discoloration gradually becomes more brownish after exposure to light. Oxytetracycline and tetracycline give a yellowish color, whereas chlortetracycline tends to cause a brownish-gray color. Tetracycline itself fluoresces under ultraviolet light and, accordingly, the teeth involved by its discoloration also fluoresce a bright yellow under ultraviolet light. However, in time this fluorescence gradually diminishes. It has been shown by Wallman and Hilton and by Zussman that the dentin is more heavily stained than the enamel.

Minocycline hydrochloride causes discoloration of the skin, nails, conjunctiva, bone, and teeth. Palate or anterior alveolar mucosa has a distinctive blue-gray appearance due to the black bone showing through the thin, translucent mucosa. The incisal edge of the fully erupted teeth reveal a blue-gray discoloration, with the middle one third being maximally involved and the exposed roots of the erupted teeth reveal dark green discoloration. The roots of developing teeth show a dark black color.

Clinical Features

Cancer chemotherapeutic agents are grouped into: (1) alkylating agents, (2) antimetabolites, (3) antitumor antibiotics, (4) plant alkaloids, (5) nitrosoureas, (6) enzymes, (7) hormonally active agents, and (8) miscellaneous compounds.

Because the major effect of these materials on cells and tissues is similar, regardless of each agent’s specific mechanisms of action, there are a few general manifestations of the group as a whole that can be emphasized. These are: (1) alopecia, due to arrest of mitosis of the rapidly germinating hair roots, (2) stomatitis, which may take a variety of forms, and (3) radiation recall or radiation sensitization, a reactivation of radiation reaction within the field of radiation following administration of certain of the antineoplastic agents.

Oral Manifestations

The most common oral reaction is mucosal erosion and ulceration, frequently diffuse and multiple, often related to the neutropenia produced by the drug but occasionally occurring in its absence. This may occur anywhere in the mouth but is most likely to be seen on the lips, tongue, and buccal mucosa. Hemorrhage is also a common manifestation resulting from the thromboeytopenia secondary to the drug therapy. These reactions do not occur following use of all cancer chemotherapeutic agents but are especially common with the alkylating, antimetabolite, and antitumor antibiotic groups.

Another oral finding in patients undergoing this type of therapy is the presence of any one of a variety of specific or nonspecific infections (commonly herpes simplex infection, candida infection, or infection by staphylococcal or streptococcal organisms), especially since many of these patients are also immunosuppressed. Finally, hyperpigmentation of oral mucosa has been reported occasionally, especially in patients receiving alkylating agents and antitumor antibiotics.

Treatment

There is no specific treatment for the oral lesions which, although severe, must be considered of only secondary importance to the patient’s major problem.

Management

In those cases in which the trauma is not immediately self-corrective, it is imperative that correction of the occlusal relation, elimination of cuspal interference, and fixation or splinting of loose teeth be carried out to prevent further damage.