ASSUMED KNOWLEDGE

It is assumed that at this stage you will have knowl-edge/competencies in the following areas:

If you think that you are not competent in these areas, revise them before reading this chapter or cross-check with relevant texts as you read.

INTENDED LEARNING OUTCOMES

At the end of this chapter you should be able to:

THE IMPORTANCE OF THE MAXILLARY ANTRUM TO DENTAL SURGERY

The maxillary sinus is often referred to as the maxillary antrum (or more simply the ‘antrum’). It is important to the dental surgeon because of its close relationship to the posterior maxillary teeth (generally from first premolar to third molar). The proximity varies between individuals (Fig. 15.1) but tends to increase with age as the antrum enlarges. The antrum can encroach into alveolar bone after tooth extraction, and periapical bone loss resulting from dental disease may further decrease the amount of bone separating it from the teeth. This close anatomical relationship can lead to diagnostic difficulties because both the antrum and the maxillary teeth are innervated by branches of the maxillary division of the trigeminal nerve. In addition, infection may spread from the periapical region of the posterior maxillary teeth to the antrum (and in the opposite direction) and the antrum is at risk of iatrogenic damage during certain dental procedures.

Fig. 15.1 (a) A small maxillary antrum that does not reach the apex of the second premolar. (b) A large maxillary antrum that reaches to the apex of the lateral incisor.

The ability to distinguish between dental and antral symptoms enables the dental surgeon to decide when dental treatment is indicated and when referral (e.g. to a general medical practitioner, an oral and maxillofacial surgeon or an ear, nose and throat (ENT) surgeon) is appropriate.

The antrum is visualized on oral and facial radiographs (notably periapical views of the posterior maxillary teeth, orthopantomogram (OPT) and occip-itomental views) and a knowledge of its normal radiographic appearance is essential in the diagnosis of both dental and antral disease. Evidence of antral pathology may be incidentally discovered by the general dental practitioner (GDP) on these radiographs.

Although the GDP is unlikely routinely to perform elective surgery within the antrum, there will be occasions when dentoalveolar surgery with a degree of antral involvement is necessary—for example, to repair a newly created oroantral communication. It is necessary for the GDP to be able to recognize and deal with problems such as oroantral communication and foreign body in the antrum and he or she should be capable of explaining the commonly performed antral investigations and surgical procedures to a patient who requests information. The GDP may also recommend other procedures that involve antral surgery (e.g. ‘sinus lift’/alveolar ridge augmentation procedures used prior to the placement of osseointegrated implants).

DISTINGUISHING SIGNS AND SYMPTOMS OF DENTAL PATHOLOGY FROM THOSE OF SINUSITIS

Maxillary sinusitis is common and the dentist needs to be able to distinguish it from dental disease. It is usually an acute condition, but chronic sinusitis may also develop following an acute episode and may persist or recur if drainage from the antrum to the nasal cavity is poor or when a foreign body is retained.

Acute sinusitis may affect any of the paranasal sinuses but is usually confined at any one time to a single sinus. It is a bacterial infection and typically occurs after a viral upper respiratory tract infection (URTI) (Haemophilus, Pneumococcus, Streptococcus, Staphylococcus species and anaerobes are commonly found).

Maxillary sinusitis is usually related to impaired antral drainage, which may be caused by:

Accumulated secretions become infected, allowing a collection of pus to develop in the antrum.

Dental diseases (including periapical pathology, infected odontogenic cysts and periodontal disease) may also cause sinusitis. Other possible causes include the presence of contaminated foreign bodies, trauma or infections of non-odontogenic cysts or malignant tumours.

THE INVESTIGATION OF ANTRAL DISEASE

A diagnosis of sinusitis can usually be made from the findings of the history and examination. The teeth and surrounding tissues should be examined for disease (although remember that sinusitis may itself have a dental cause). Transillumination, using a torch shone from inside the mouth, may demonstrate antral congestion but this is a rather crude test and may fail to detect tumours. Radiographs are not usually required to confirm the diagnosis of sinusitis as the diagnosis can be made on clinical grounds alone. Radiographs are only required to exclude the possibility of dental disease, trauma or pathology within the antrum. If pathology or trauma is suspected, occipitomental radiographic views are often taken in specialist centres. A ‘fluid level’ may be visible which represents a collection of pus, although following trauma it may be due to the presence of blood and suggests that there is a fracture of the wall of the antrum. Opacities due to polyps, cysts, thickened antral lining, tumours and radio-opaque foreign bodies may also be demonstrated.

Other useful radiographs include:

Much useful information can be gathered by endoscopy of the antrum. This is better performed by someone with experience of endoscopy in the region (such as an ENT surgeon).

DENTAL EXTRACTIONS AND THE ANTRUM

The following complications may occur during the extraction of posterior maxillary teeth because of their close proximity to the maxillary antrum:

Maxillary premolars and permanent molars are most frequently implicated, although permanent canines may occasionally be very close to the antrum. Complications may also occur during the surgical removal of impacted partially erupted or unerupted teeth (e.g. canines, premolars and third molars). The extraction of deciduous teeth does not present a risk due to the relatively small size of the antrum in children and the presence of the developing permanent teeth.

An assessment of the size and proximity of the antrum before extraction or periapical surgery on a posterior maxillary tooth may help to anticipate and avoid these complications. When a complication does occur, it should be recognized and dealt with promptly.

The following factors should be taken into account during clinical and radiographic examination in order to anticipate and avoid complications:

If the dental history reveals the creation of an oroantral communication during a previous extraction there is likely to be an increased risk of this complication occurring during the subsequent extraction of adjacent or contralateral teeth. Similarly, if there is a history of difficult extractions, due perhaps to hypercementosis or dense bone, there may be an increased risk of tuberosity fracture.

OROANTRAL COMMUNICATION AND FISTULA

An oroantral communication (OAC) is an abnormal connection between the oral and antral cavities; an oroantral fistula (OAF) is an epithelialized OAC (although the terms OAC and OAF are often used interchangeably).

The creation of an OAC most commonly follows the extraction of a maxillary tooth closely related to the antral floor (typically the first molar (Fig. 15.2), which lies close to the lowest point of the antral floor, although any premolar or molar may be affected). An OAC may also form as a result of an alveolar fracture running through the antral floor or wall, or be due to direct trauma from a bur or chisel. Left untreated, an OAC may heal spontaneously or persist as an OAF (Fig. 15.3).

Fig. 15.2 A maxillary molar in close relation to the maxillary antrum.

Fig. 15.3 Oroantral fistula in the first molar region with proliferation of soft tissue.

The following signs indicate OAC formation:

Further options for the treatment of OAC/OAF

If the immediate measures are insufficient or fail to lead to healing of an OAC (e.g. in the case of a large OAC) further treatment becomes necessary. Tissue from local flaps is most often utilized to close oroantral defects, although distant flaps (e.g. from the tongue) and grafting are also possible. The choice of method depends on the size and position of the communication. Of the variety of local flaps which have been described the most common is the buccal advancement flap.

Buccal advancement (Rehmann’s) flap (Fig. 15.4)

This technique is suitable for the closure of new OACs and chronic OAFs.

Fig. 15.4 Closure of an oroantral fistula with a buccal advancement flap.

(a) The incisions outlined from the buccal and occlusal aspects.

(b) Incision of periosteum only, high up in the reflection of the sulcus.

(c) Extension of the flap following ‘release’.

(d) Closure with vertical mattress sutures, seen from the occlusal aspect.

1. A sharp probe is used to locate the edges of the bony defect (which may be considerably larger than the soft-tissue defect—especially in a long-standing OAF).

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2. The epithelium lining the fistula tract (if present) and soft-tissue margins is excised with a No. 11 scalpel blade, leaving a 2- to 3-mm rim of exposed bone, which enables the suture line to rest on sound bone. Alternatively, the fistula may be turned in on itself, up into the antrum. This presents, in the place of an empty tract, a connective tissue surface for the underside of the buccal flap to lie against.

3. A broad-based three-sided buccal mucoperiosteal flap, which extends to the full depth of the sulcus, is cut and reflected.

4. The periosteum lining the inner surface of the flap is cut parallel to and close to its base, allowing the flap to be stretched (‘advanced’) without tension to meet the palatal mucosa. Although the full width of the periosteum must be divided in order to mobilize the flap, care must be taken not to compromise the blood supply by creating a ‘button-hole’ in the thin buccal tissue. To prevent this the back of a scalpel blade may be used with repeated light strokes until the periosteum is cut through.

5. The palatal margin is slightly undermined and the wound closed with mattress sutures. This author recommends 3/0 non-resorbable (or a long-lasting resorbable) suture material and that sutures should be retained for 10–14 days.

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This is a simple, well-tolerated procedure with a good success rate. It can be performed under local anaesthesia in a cooperative patient and may be performed in general dental practice if adequate skill and facilities are available. Although this technique initially reduces sulcus depth, this is usually temporary.

In OAFs with large bony defects or where previous surgical closure has been unsuccessful, more complicated surgery may be required to close the defect. An adaptation of the buccal advancement flap utilizing a buccal fat pad (BFP) graft is often used. This is performed under GA in order to achieve adequate analgesia and as surgery is more prolonged. A broad-based three-sided mucoperiosteal flap is raised and periosteum incised (Fig. 15.4). The BFP is then located using a vestibular incision in the region of the upper first permanent molar and mobilized using blunt dissection with artery forceps. This tissue is then advanced to cover the bony defect and the mucoperiosteal flap is sutured using a non-resorbable material. A high success rate using the BFP graft has been reported.

Palatal rotation flap (Fig. 15.5)

This is used less commonly than the buccal advancement flap.

Fig. 15.5 Closure of an oroantral fistula with a palatal rotation flap.

(a) The incision outlined.

(b) The flap mobilized, rotated into the defect and sutured.

1. The epithelial lining (if present) is excised with a No. 11 scalpel blade (Fig. 15.5a).

2. An elongated full-thickness mucoperiosteal palatal flap, which follows the course of the greater palatine artery and which extends for a short distance anterior to the oroantral defect is designed, cut and raised. It should be long enough for its free end to be rotated to cover the defect. As the flap relies upon the greater palatine artery for its blood supply, care must be taken not to cut or damage this vessel or to reduce flow through it by bending the flap too acutely.

3. The flap is sutured across the defect (Fig. 15.5b) using mattress sutures (as for the buccal advancement flap). The resultant area of exposed bone is covered with a dressing such as ribbon gauze (soaked in an antimicrobial agent) held in place with sutures, or a periodontal dressing (secured with sutures or an acrylic base-plate), which should be retained for 10–14 days.

This technique provides a thick, strong repair, which heals readily due to its good blood supply and does not adversely affect the buccal sulcus. However, palatal flaps are relatively inelastic and can be difficult to raise and mobilize. In addition, it can be difficult to judge the precise length of tissue required. Under local anaesthesia, this procedure is more unpleasant for the patient than the buccal advancement flap is and a raw area of exposed palatal bone is produced. Although, it could be tackled in general dental practice under local anaesthesia it is more commonly performed in a specialist setting under GA.

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For all methods of OAC/OAF closure, the patient should be warned not to blow the nose during the first 10 postoperative days, as this raises pressure within the antrum and may disrupt the healing tissue. Compliance with this instruction may be greater if a patient is given a simple explanation for it. Prophylactic antibiotics and nasal decongestant drops are prescribed by some surgeons to prevent infection and encourage antral drainage.

FOREIGN BODIES IN THE ANTRUM

This complication occurs when teeth or roots are closely related to the antrum. Roots of maxillary premolars and molars are the most common foreign bodies although whole teeth may also be displaced into the antrum. Their entry into the antrum occurs during attempts at removal and is associated with OAC formation. Other foreign bodies include materials introduced during root-filling procedures, via an OAF (food, impression material, cotton buds) and during trauma.

The displacement of a root into the antrum occurs because of:

As a root can be pushed through a very thin antral floor using the lightest touch it is essential to avoid applying any upward pressure. The risk is particularly high when an elevator is used blindly within a socket. Root removal should therefore be performed under direct vision using a transalveolar approach. Elevators are used to apply gentle pressure towards the mouth (never towards the antrum) and forceps should not be applied without a clear view of both the palatal and buccal root surfaces. Consideration may be given to leaving a small (less than 3 mm) vital root fragment rather than risk displacing it into the antrum. If this decision is taken the patient should be informed and the reasons explained, relevant radiographs should be taken to confirm the size and position of the retained root and an entry should be made in the patient’s notes. The root should be reviewed periodically and removed if symptoms develop. Whole teeth may be pushed into the antrum, with partially erupted and unerupted teeth, especially those with a single conical root, being at the greatest risk (e.g. upper third molars, impacted canines and premolars).

A root may be displaced:

A root not removed with the tooth must be accounted for, due to the dangers of inhalation and infection. First look in the oral cavity, socket and adjacent tissues, next search extraorally and then take radiographs if necessary. Radiographs that are suitable for demonstrating a root in the antrum include periapical (Fig. 15.6) and oblique occlusal views or an OPT. The presence of a root canal confirms that a radio-opaque image represents a root.

Fig. 15.6 A root displaced into the maxillary antrum (arrows).

Roots should be removed from the antrum as soon as possible to prevent an OAF and chronic sinusitis from developing. If left they may become embedded in granulation tissue, polyps or fibrous tissue or an antrolith (antral ‘stone’) may form around them. They are occasionally expelled through an OAF into the mouth or through the ostium into the nose from where they may be inhaled or expelled by sneezing. In general dental practice, the recommended immediate treatment for a root in the antrum is to provide simple treatment for the OAC (see above), inform the patient and arrange prompt referral to an oral and maxillofacial surgeon.

Roots can sometimes be removed through the extraction socket, although often access is better via a window in the anterior antral wall, made using the Caldwell-Luc operation. As an alternative, consideration should be given to possible removal of small roots by endoscopy.

Caldwell-Luc operation (Fig. 15.7)

This gives surgical access to the interior of the antrum though the mouth and is usually performed in hospital under GA. It can be used to remove roots, teeth and other foreign bodies from the antrum.

Fig. 15.7 The Caldwell-Luc operation.

1. A horizontal incision is made in the buccal sulcus from the upper lateral incisor to the upper first molar and a mucoperiosteal flap is raised (in the edentulous ridge a two-sided buccal flap with an anterior relieving incision is used). A chisel or bur is used to create an opening in the antral wall in the canine fossa.

2. The root is located using suction and good lighting and removed with an artery clip or Fickling forceps.

3. If blood clot, granulation tissue or polyps are present they may be carefully removed, but the antral lining should be disturbed as little as possible (problems with mucus clearance and subsequent chronic sinusitis may result).

4. Finally, the antrum is irrigated with normal saline and the incision is closed with interrupted non-resorbable sutures.

Summary of extractions and the maxillary antrum

• The extraction of maxillary teeth may be complicated by OAC/OAF formation, the introduction of roots, teeth or other foreign bodies into the antrum and fracture of the maxillary tuberosity

• These complications are more likely to occur where the antrum is large and closely related to the teeth

• The GDP should know how to predict, avoid, detect and treat these conditions and should understand whether treatment by a GDP or a specialist is appropriate

FACIAL FRACTURES INVOLVING THE ANTRUM

Fractures of the antral walls occur in several common types of facial fracture including zygomatic complex, mid-third (Le Fort I, II and III), orbital blow-out and alveolar fractures (see Ch. 13). The presence of a fracture through the antral wall does not preclude the extraction of a maxillary molar or premolar, although forceps should be avoided in favour of a surgical approach in the initial 6 weeks following trauma.

ANTRAL CYSTS AND TUMOURS

Antral mucosal cysts are frequently discovered as incidental findings on dental radiographs (Fig. 15.8). They are generally symptomless and have no long-term significance, but care should be taken to differentiate between truly antral lesions and cysts of odontogenic origin (apical cysts, dentigerous cysts and odontogenic keratocysts), which do require treatment.

Fig. 15.8 A benign antral mucosal cyst (arrows) may be an incidental finding on a dental radiograph.

Benign tumours arising in the antrum include papillomas and osteomas. Although they rarely cause symptoms, they may interfere with antral drainage or cause nasal obstruction by growing through the ostium, and they occasionally herniate through an OAC. More often, however, they are discovered incidentally on radiographs.

Malignant tumours arising in the antrum are less common, but often have a poor prognosis as they tend to present at an advanced stage. This is because they develop in a concealed location and early symptoms may be absent, or mistaken for sinusitis. When symptoms of antral malignancy do develop, a patient may consult a dentist believing he or she has a dental problem. This makes it especially important that dentists are able to recognize the typical presenting signs and symptoms (see also Ch. 10, p. 136). These vary according to the direction in which the tumour is spreading (see box).

Radiographs of early malignant antral tumours appear normal or may show cloudiness or an irregular soft-tissue outline. Erosion of the antral wall is seen in later stages. Whenever antral malignancy is suspected referral should be made without delay to an oral and maxillofacial surgeon, initially by telephone or fax.

THE ANTRUM AND FACIAL PAIN

Sinusitis and antral malignancy both produce facial pain, which may not have an immediately obvious cause. These conditions should be included in the differential diagnosis of facial pain (their typical signs and symptoms are described above and facial pain is discussed in detail in Ch. 16).

PHARMACOLOGICAL TREATMENT OF ANTRAL DISEASE

Antibiotics, decongestant nasal drops and steam inhalations are prescribed for the prevention of sinus infection following the creation of an OAC. Broad-spectrum antibiotics are useful in the treatment of acute sinusitis (although they are not a substitute for the drainage of pus) and decongestant nasal drops and steam inhalations can be used to encourage drainage. An analgesic such as paracetamol or ibuprofen may be recommended for relief of pain in acute sinusitis.

SELF-ASSESSMENT

Fig. 15.9 See question 2.

Answers on page 269.