Orthodontics II

Natal teeth: Natal teeth are usually lower incisors that are erupted at birth or appear soon after. Removal is indicated only if they interfere with suckling or if they are so mobile as to be at risk of inhalation.

Eruption of teeth: Other than natal teeth, the following points should be borne in mind:

Factors causing premature exfoliation or delay in the eruption and exfoliation of primary or permanent teeth are given in Table 10.1.

To ensure that any deviation in the normal eruption sequence is detected early, clinical vigilance is required during the developing dentition, supported by radiographic investigations where necessary. Particular attention should be given to the permanent maxillary incisors and canines, as early recognition of an anomaly in their eruption improves the prognosis.

• third molars (25–35%)

• upper lateral incisors (2%)

• lower second premolars (3%)

• lower incisors (~0.2%).

Absent third molars: Extraction of a second molar, either to facilitate distal movement of the upper buccal segments or to relieve posterior crowding, should not be considered in the absence of a third molar. These start to calcify any time between 8 and 14 years.

Absent upper lateral incisors: Management options for the space created by absent upper lateral incisors are:

The final decision depends on:

The possible plans are best assessed by carrying out a trial set-up of each on duplicate study models, followed by joint consultation with a restorative colleague.

Absent second premolars: The primary second molar should be retained where the arch is uncrowded or aligned. If the tooth starts to submerge, an occlusal onlay may be placed to maintain it in function. Removal of the lower second primary molar shortly after eruption of the lateral incisors will encourage spontaneous space closure in mildly crowded mouths, but in those with marked crowding, its extraction should be delayed until orthodontic treatment commences so that the resulting space may be used for arch alignment. In the upper arch, extraction of the second primary molar is again best deferred until orthodontic treatment is about to start. Rarely, a lower second premolar develops late and necessitates an alteration in the original treatment plan.

Absent lower central incisors: In the absence of permanent lower central incisors, root resorption and progressive incisal wear may lead to loss of the primary incisors in the late mixed dentition, although occasionally they can last for longer. A fixed appliance may be needed to close incisor spacing in a crowded mouth or to align the lateral incisors prior to placement of resin-retained bridgework in an uncrowded arch. Where one or both lower central incisors is missing and the space is closed orthodontically, mild crowding may result in the upper labial segment as six anterior teeth are arranged around four or five lower teeth.

• in males than in females

• in the permanent than in the primary dentition (respective incidences 2% and 1%)

• in children with cleft of the lip and alveolus and cleidocranial dyostosis.

Conical teeth: Conical teeth occur between the upper permanent central incisors; they are often singular but can sometimes occur in combination with others of similar form. They may have no effect if they are well above the apices of the incisors. If there is no risk of damage to adjacent teeth with tooth movement, they can be left in place and observed. Often, however, they may displace the adjacent teeth, perhaps creating a large diastema, or they may delay eruption. In these instances, removal is indicated. Occasionally, a conical supernumerary tooth erupts and can be extracted.

Tuberculate teeth: Tuberculate teeth are the most common cause of an unerupted permanent maxillary central incisor. Suspicion should be raised if the lateral incisors erupt in advance of the centrals. In these cases, a radiograph of the premaxilla should be taken to allow early detection and localisation of any supernumerary, which should then be surgically removed. An attachment with gold chain or a magnet should be bonded to the unerupted incisor to allow provision for orthodontic alignment if the tooth fails to erupt spontaneously within 12 months of surgery. In conjunction with surgery, space to accommodate the unerupted tooth must be maintained or opened by appliance therapy; the latter may entail extraction of the upper primary canines.

Supplemental teeth: The supplemental tooth resembles the normal tooth in morphology and commonly produces crowding or displacement of adjacent teeth. Usually, the tooth, which is similar to the contralateral tooth, is better retained (provided it is not severely malpositioned) and the other incisor is extracted.

• the patient’s age

• the degree of crowding

• the tooth extracted

• the arch from which it is removed

• the type of occlusion.

Space maintenance for early tooth loss: Space maintenance is indicated:

A removable appliance will usually suffice in the upper arch but a lingual arch soldered to bands cemented to molar teeth is best in the lower.

• a midline supernumerary tooth

• missing or small upper lateral incisors

• incisor proclination in class II division 1 malocclusion (Section 10.3) or due to a digit-sucking habit

• a more generalised spacing condition due to mismatch in tooth/arch size (Section 10.2).

• procline the upper incisors

• retrocline the lower incisors

• increase the overjet, often asymmetrically

• reduce the overbite

• lead to a crossbite tendency of the buccal segments.

Transposition: Transposition is when the position of the canine is interchanged with that of an adjacent tooth. In the upper arch, the maxillary canine and first premolar, or the lateral incisor and canine, are involved, although the former arrangement is more common. In the lower arch, this anomaly affects solely the lateral incisor and canine teeth.

Estimating the maxillary canine position:

Management of canine displacement: The management of buccal or palatal maxillary canine displacement including transposition is described in Table 10.2.

Skeletal factors: The skeletal pattern may be class I, class II or class III with the incisors compensating for any underlying skeletal discrepancy. An increase in lower anterior face height or a mild transverse skeletal discrepancy may also occur, creating an anterior open bite or buccal segment crossbite, respectively.

Soft tissues factors: Apart from bimaxillary proclination, where labial movement of the incisors may result from tongue pressure in the presence of unfavourable lip tone, the soft tissues are not prime aetiological factors.

Dental factors: A tooth/dental arch size discrepancy leading to crowding or spacing is the principal cause of class I malocclusion. Other factors, however, such as early loss of primary teeth, large or small teeth, supernumerary or absent teeth, can also influence any inherent dento-alveolar disproportion.

• ‘The lower incisor edges occlude with, or lie immediately below, the cingulum plateau of the upper central incisors’ (British Standards Institute classification). Not all of the incisors, however, may relate in this manner. Provided the overall anteroposterior labial segment relationship is normal, even where a crossbite exists on one or two upper incisors, the incisor relationship may be regarded as class I.

• The molar relationship is variable and depends on whether mesial drift has followed any previous extractions.

• Crowding is often concentrated in the upper canine and lower second premolar areas as these teeth often erupt last in each arch.

• Crowding may also displace one or more teeth into crossbite and create a premature contact on closure, with associated mandibular displacement and centreline shift.

Crowding: The possible measures to be considered in relation to the management of crowding have been presented in Sections 9.4 and 10.1. Some basic guidelines, however, regarding the management of crowding in class I malocclusion are as follows:

Skeletal relationships: Although the skeletal relationship is usually class II, class II division 1 malocclusion may exist on a class I or mild class III skeletal pattern. Where a class II skeletal pattern is present, mandibular deficiency is almost entirely the primary cause, although excessive maxillary growth or a combination of the two may be factors in other instances. In contrast, the developmental position or inclination of the teeth resulting from soft tissue or digit-sucking influences are to blame where the skeletal pattern is class I or mildly class III. The anterior vertical proportions of the face vary, and where these are greatly increased or reduced, treatment is likely to be difficult.

Lips, tongue and habits: The effects of the lips and tongue on the incisor position are determined principally by the skeletal pattern and thereafter by the manner in which an anterior oral seal is achieved. Where the skeletal pattern is class II, an acceptable incisor relationship may be achieved by proclination of the lower incisors under the influence of the tongue. In general, however, the greater the class II skeletal discrepancy, the more likely the lips are to be incompetent and to contribute to upper incisor proclination. Where lip incompetence exists along with a class II skeletal pattern and a reduced lower facial height, an anterior oral seal is likely to be produced by the lower lip lying under the upper incisors. This worsens the overjet by proclining the upper and retroclining the lower incisor teeth. In rare cases, the lower lip may be hyperactive and contribute to a class II division 1 malocclusion by solely retroclining the lower incisors. Where the lower facial height is increased, an anterior oral seal is often produced largely by forward positioning of the tongue, thus tending to reduce the overbite further and compensate for the class II discrepancy by proclining the lower incisors.

In very rare instances, a primary atypical swallowing behaviour will cause an overjet increase, but distinguishing this from an adaptive tongue thrust is difficult. The effect of a digit-sucking habit is to procline the upper incisors and retrocline the lower incisors although the overjet increase may be asymmetric depending on the positioning of the digit.

Crowding: Labial displacement of the upper or lower incisors caused by crowding may respectively worsen or ameliorate an overjet.

• ‘The lower incisor edges lie posterior to the cingulum plateau of the upper incisors; there is an increase in overjet and the upper incisors are usually proclined’ (British Standards Institute classification).

• This malocclusion is seen in about 15–20% of Caucasians and the upper incisors are often traumatised because of the increased overjet: the likelihood increasing more than two-fold where the overjet exceeds 3 mm compared to where it is less than 3 mm.

• Drying of the gingivae labial to the upper incisors may occur with grossly incompetent lips, and this will aggravate an established gingivitis.

• The overbite varies depending on the skeletal pattern, the presence or absence of an adaptive tongue thrust on swallowing, or the existence of a digit-sucking habit. It is commonly increased and complete, and sometimes traumatic, with the lower incisors impinging on the gingivae palatal to the upper incisors. It may also be incomplete or tend to an anterior open bite.

• Usually the molar relationship is class II, provided mesial drift following early loss of primary teeth has not occurred.

Special considerations in treatment planning:

Treatment in class I or mild class II skeletal relationship: Rarely, will treatment by tipping movements and upper removable appliance therapy alone be possible. Where the FMPA is average or slightly reduced, the arches are aligned and uncrowded and the upper incisors sufficiently proclined that, when the overjet is reduced, they will form no less than a 95° angle to the maxillary plane, then this may be considered. The highest quality outcome, however, is to be obtained with fixed appliances. Where occlusal factors (in particular, the inclination of the canines and maxillary incisors) are not amenable to tipping movements, fixed appliances are indicated (often in combination with extractions to allow relief of crowding) for correction of the incisor and buccal segment relationships. Removal of lower second and upper first premolars often favours the attainment of these occlusal goals. In the mixed dentition with a mild/moderate class II pattern, overjet reduction may be carried out using a functional appliance, although this is often followed by a phase of fixed appliance treatment, sometimes in combination with extractions, to optimise the final occlusal result (see Section 10.1).

Treatment in moderate-to-severe class II skeletal relationship: Three possibilities exist in relation to treatment in moderate-to-severe class II skeletal relationships.

Retention and post-treatment stability: The interincisal angle should be within normal limits, the overjet completely reduced with the upper incisors in soft tissue balance (i.e. no tongue thrust) and the lower lip covering at least one-third of their labial surface. Where these criteria are met, the prospect of stability is good. Retention planning is discussed elsewhere (see Section 11.4) but retention until growth is complete is required following functional appliance treatment.

Skeletal relationships: The skeletal pattern in division 2 malocclusion is usually mildly class II, although it may be class I or mildly class III. A reduced lower facial height is common with an associated anterior mandibular growth rotation, which tends to increase the overbite. A relatively wide maxillary base may lead to a lingual crossbite of the first premolars.

Soft tissues: The high lower lip line (covering more than one-third of the upper incisor crowns) and resting pressure (about 2.5 times greater than that of the upper lip) are the most significant aetiological factors in retroclination of the upper incisors. The lower lip level depends largely on the lower anterior facial height; the more reduced the lower anterior facial height, the higher the lower lip line. Where the lower lip is also hyperactive, bimaxillary retroclination will result.

Dental factors: The upper incisor cingulum is often reduced or absent, which may exacerbate the overbite. In addition, there is an increased likelihood of the teeth being smaller than normal, as is the chance of a more acute crown/root angulation. Retroclination of the upper, and commonly of the lower, incisors also makes existing crowding worse.

• ‘The upper central incisors are retroclined. The overjet is minimal but may be increased’ (British Standards Institute classification).

• The upper lateral incisors are often proclined and mesiolabially rotated but they may also be retroclined.

• Occasionally upper and lower incisors are retroclined, usually associated with a high lower lip line where the lip is hyperactive.

• The overbite may be traumatic: palatal to the upper incisors, labial to the lowers or, in severe cases, in both locations.

• Because of the discrepancy in arch widths and the class II skeletal relationship, a scissors bite is often present in the first premolar area.

Treatment planning: The following factors in particular must be considered in relation to treatment planning.

Treatment:

Post-treatment stability: Two features of class II division 2 malocclusion are particularly prone to relapse:

Rotational correction early in treatment and pericision should be undertaken to help to prevent relapse, but as these do not guarantee stability, bonded palatal retention long term is advisable, ensuring that this is supervised appropriately.

An increase in lower facial height and inferior movement of the lower lip away from the upper labial segment aids correction of the interincisal angle but is dependent on favourable vertical facial growth. Even where these features are evident, the closing pattern of mandibular growth tends to increase the overbite into adulthood. Following overbite correction, an upper removable retainer incorporating a flat anterior bite plane is recommended until growth is complete, but in many cases long-term retention is advisable.

Skeletal pattern: The skeletal pattern is most usually class III although it may be class I with the class III malocclusion due to incisor position or inclination. Mandibular, maxillary and cranial base factors often make a combined contribution to the underlying class III skeletal relationship. The mandible is longer; the glenoid fossa positioned more forward, the maxilla shorter and/or retrognathic in addition to a shorter anterior cranial base. The vertical relationship of the skeletal bases varies from increased to average or reduced and is generally reflected in the depth of overbite, which may alter depending on the pattern of facial growth. Where this is vertical rather than horizontal, an anterior open bite is likely.

Commonly, a transverse discrepancy exists in the dental base relationship because of the narrow maxillary and wider mandibular bases, although this is often worsened by the class III skeletal pattern.

Soft tissues: The soft tissues contribute little to the aetiology of the malocclusion. Instead, where the lips are competent, the lips and tongue induce retroclination of the lower and proclination of the upper incisors (dento-alveolar compensation); as a result, the incisor relationship masks the true severity of the skeletal pattern. Where the lower anterior facial height is increased, however, the lips are frequently incompetent, with an adaptive tongue thrust on swallowing which may procline the lower incisors.

Dental factors: Crowding is more common and more severe in the upper than in the lower arch, often resulting from the difference in length and width of the arches: the upper frequently is short and narrow compared with a longer and wider lower arch.

• ‘The lower incisor edges lie anterior to the cingulum plateau of the upper incisors, the overjet is reduced or reversed’ (British Standards Institute classification).

• The overbite may be increased, average or reduced. Where the vertical facial proportions are increased, there is often an anterior open bite.

• Frequently, the upper incisors are proclined and the lower incisors retroclined, compensating for the underlying class III skeletal pattern.

• Upper arch crowding is common, often because of a short and narrow dental base, while the lower arch is more commonly aligned or spaced.

• Crossbites of the labial and/or buccal segments are common, resulting from the underlying class III occlusal discrepancy as well as from differences in the length and width of the arches. Crossbites may be associated with a mandibular displacement (see Section 9.3), particularly where a unilateral buccal segment crossbite exists. In the case of an anterior crossbite, the possibility of displacement should be assessed by checking if the patient can bite with the upper and lower central incisal edges contacting. Lower incisor mobility and occasionally gingival recession may be associated with the anterior crossbite.

The degree of anteroposterior and vertical skeletal discrepancy: The degree of anteroposterior and vertical skeletal discrepancy is the most important factor in planning treatment and assessing the prognosis. As it is usually directly reflected in the facial and dental appearance, it will influence also the complexity of treatment undertaken through the patient’s perception of these features.

The potential direction and extent of future facial growth: The general trend for downward and forward mandibular growth to surpass that of the maxilla is unfavourable for class III correction. Relevant family history, the age and gender of the patient, together with assessment of the vertical facial proportions, may help in making a ‘guesstimate’ as to the likely changes with growth. A reduced or average anterior facial height is often associated with a closing mandibular growth rotation, and a horizontal pattern of mandibular growth worsening the reverse overjet. With an increased vertical facial height, there is a tendency for a backward mandibular rotation to increase the likelihood of anterior open bite.

The incisor inclinations: The incisor inclinations indicate the degree of dento-alveolar compensation; if this is already marked, further compensation by orthodontic means is unlikely to be stable or to produce an aesthetic result.

The amount of overbite: It is essential that there is an adequate overbite post-treatment to improve the prospects of stable overjet correction. Where the overbite is average or increased pretreatment, stability is more likely than where the overbite is reduced. Proclination of the upper incisors reduces the overbite while retroclination of the lower incisors increases it. Both movements may be necessary in some cases.

The ability to achieve an edge-to-edge incisor relationship: If it is not possible to achieve an edge-to-edge incisor relationship, correction of the incisor relationship by simple means is unlikely.

The degree of upper and lower arch crowding: The following should be borne in mind. Upper arch extractions should be delayed until a reverse overjet and/or buccal crossbites have been corrected. This may provide space for relief of mild-to-moderate upper arch crowding. Where extractions are undertaken in the upper arch only, the reverse overjet may worsen with palatal movement of the upper labial segment. Where mid upper arch extractions are necessary, extraction of lower first premolars is usually advisable to allow correction of the incisor relationship.

Treatment in class I or mild class III skeletal pattern: Where the lower anterior facial height is increased, the overbite is usually minimal and the incisor relationship should be accepted. Treatment should focus on aligning the arches, with possible extractions. Upper arch expansion for crossbite correction will create space for relief of crowding. When this is indicated, fixed appliance mechanics must be used to minimise unfavourable dropping of the palatal cusps of the premolars and molars, as this will reduce the overbite further.

Provided the lower anterior facial height is average or reduced, with a normal or increased overbite and upright upper incisors, proclination of the upper labial segment may be undertaken. This is often best carried out in the early mixed dentition before the permanent canines move labial to the lateral incisor roots, thereby increasing the risk of resorption if their proclination is attempted. In such cases, treatment is best deferred until the canines have been retracted, removing the obstruction to crossbite correction of the lateral incisors. An upper removable appliance, incorporating a screw or Z-springs and posterior capping, may be used to correct the anterior crossbite (Fig. 10.2), but a fixed appliance may be indicated depending on the presence of other occlusal features.

The need for upper arch extractions should be reassessed after the incisor relationship has been corrected, as some additional space for relief of crowding will be forthcoming from anteroposterior expansion. Movement of the upper buccal segments distally is not a favoured option as restraint of maxillary growth is likely. Often, extraction of the lower primary canines in the early mixed dentition, or of first premolars in a crowded lower arch in the permanent dentition, is advantageous in allowing the lower labial segment to drop lingually and increase the overbite.

Treatment in mild-to-moderate class III skeletal pattern: Where the overbite is average or increased, two options exist: growth modification or orthodontic camouflage.

Treatment in severe class III skeletal pattern:

Aetiology:

Treatment: With the exception of an anterior open bite caused by a habit, treatment is complex and is best managed by a specialist.

Skeletal factors: A mismatch in the widths of the dental arches or an anteroposterior skeletal discrepancy may produce a crossbite of a complete arch segment – a lingual crossbite commonly found in class II – whereas a buccal and/or anterior crossbite is often associated with a class III malocclusion.

Growth restriction of the maxilla following cleft repair or of the mandible secondary to condylar trauma can lead also to buccal segment crossbite.

Soft tissue factors: With a digit-sucking habit, the tongue position is lowered and contraction of the cheeks during sucking is unopposed. This displaces the upper posterior teeth palatally and often creates a crossbite.

Crowding: Where the arch is inherently crowded, the upper lateral incisor may be displaced palatally and the upper second or third molar pushed into a scissors bite.

Local causes: Retention of a primary tooth or early loss of a primary second molar in a crowded arch can lead to the permanent successor erupting in crossbite.

Treatment of anterior crossbite: Where one or two incisors are in crossbite. there is usually a mandibular displacement, and correction early in the mixed dentition is advisable provided adequate overbite exists to maintain correction. Space must be present in the arch (or can be created by extraction) to allow alignment of the tooth. If the tooth inclination is amenable to tipping, an upper removable appliance with buccal capping to free the occlusion and a Z-spring for proclination may be used (see Fig. 10.2). Anterior retention must be good to resist the displacing force caused by the action of the spring. Alternatively, an appliance with a screw section, clasping the teeth to be moved, overcomes this problem. Where insufficient overbite is likely to exist post-treatment, or the incisor is bodily displaced, treatment is better carried out with a fixed appliance in the permanent dentition. Treatment of anterior crossbite involving two or more incisors is considered in Section 10.4.

Treatment of unilateral buccal crossbite: An upper removable appliance incorporating a T-spring or screw section may often be considered for correcting a crossbite on a premolar or molar, respectively (Figs 10.3 and 10.4). However, where reciprocal movement of opposing teeth is needed, fixed attachments should be placed and cross-elastics used to achieve the desired movement. Where a single tooth is mildly displaced from the arch, relief of crowding may be necessary to aid crossbite correction. In those with more marked tooth displacement, extraction rather than orthodontic alignment may be a better option.

Where a unilateral buccal segment crossbite is associated with a mandibular displacement, this usually results from a mild mismatch in widths of the dental bases, sometimes as a result of narrowing of the upper arch caused by digit sucking. Grinding of the relevant primary teeth, where a premature contact results in a mandibular displacement, is advised to prevent the associated posterior crossbite from being carried forward to the permanent dentition. Otherwise, upper arch expansion using a removable appliance with midline expansion screw and buccal capping to disengage the occlusion, or by a quadhelix appliance, may be used for correction provided the teeth are not tilted buccally already. The quadhelix consists of a 1 mm stainless steel wire with four coils; it is attached to bands cemented to a molar tooth on each side of the arch. Alternatively, a preformed appliance may be slotted into welded attachments on the palatal aspect of the molar bands. Differential slow arch expansion anteriorly and/or posteriorly may be achieved following customary activation of half a tooth width per side. Slight overcorrection is advised to compensate for the relapse tendency. Although, treatment with an upper removable appliance or quadhelix produced similar results, treatment with a quadhelix has been shown to be more economical.

Treatment of bilateral buccal crossbite: A bilateral buccal crossbite is seldom associated with functional problems. Generally, as its existence indicates an underlying symmetrical transverse skeletal discrepancy, it is best accepted unless correction is planned as part of overall treatment, when rapid expansion of the midpalatal suture should be attempted only by a specialist. This is achieved by turning a midline screw, connected to bands cemented on first premolar and molar teeth, twice daily for 2 weeks. Expansion of the suture must be carried out no later than in early teenage years but, based on limited data, it appears that only 25% of the expansion achieved is stable long term. Surgically-assisted rapid palatal expansion (SARPE) (see Section 10.6) may be considered in the adult.

Treatment of lingual crossbite: Crowding may displace a single tooth into lingual crossbite. Once the crowding is relieved, the crossbite may be corrected, often by palatal movement of the upper unit using a buccally approaching spring on a removable appliance, provided the occlusion is disengaged. Where a complete unilateral lingual crossbite is associated with a mandibular displacement, lower arch expansion and upper arch contraction with either removable or fixed appliances can produce a stable result provided a good buccal intercuspation is achieved. Surgical correction may be indicated to correct a complete bilateral lingual crossbite or unilateral lingual crossbite with no displacement.

• Adults are generally highly motivated orthodontic patients, able to specify their concerns, but they tend to have higher expectations of the final result than younger patients.

• The dentition may be compromised because of periodontal disease, tooth loss or extensive restorative treatment. Careful pretreatment assessment is required and all systemic and dental disease must be controlled before orthodontic treatment starts. Occasionally existing bridgework may need to be removed to allow tooth movement to proceed. Often, input from a variety of other disciplines (restorative, periodontal, prosthodontic and surgical) is necessary to achieve the best result, and integrated treatment planning must be co-ordinated in a logical sequence.

• There is also a greater likelihood of systemic illness impacting on the treatment plan in adults.

• Due to the absence of growth, skeletal discrepancies (other than mild) are best dealt with by orthodontics in combination with surgery rather than by camouflage.

• Where camouflage is considered, overbite reduction by intrusion of the incisors rather than by extrusion of the molars is necessary.

• Anchorage planning is often more demanding than in the younger patient because of previous tooth loss and the possibility of reduced bony support of the remaining teeth. Headgear is not a realistic treatment option and alternatives such as palatal arches or bone anchor devices must be considered.

• Because of the reduced cell population and often reduced vascularity of the alveolar bone, the initial response to orthodontic forces is slow; however, once tooth movement starts it tends to progress as efficiently as in adolescents. The bone remodelling process necessary for tooth movement, however, is slower in those taking oral bisphosphonates for osteoporosis (see Section 9.3).

• Some pain is common for 3–4 days following appliance adjustment, and light forces should be applied initially in all cases and throughout treatment where periodontal support is compromised.

• To improve the appearance of the appliance, aesthetic brackets or lingual appliances are options. In selected cases, treatment by a series of clear vacuum-formed thermoplastic aligners may be considered.

• Bands should be avoided in those with periodontal breakdown; fully bonded appliances should be used instead. Indeed there is an increasing trend to use bonded attachments on all teeth in adults due to longer clinical crowns.

• Retention may be lengthy or permanent.

Adjunctive treatment: Adjunctive treatment involves carrying out tooth movement to correct one aspect of the occlusion to improve dental health or function, although the final occlusal result may not be necessarily ideal or class I. Treatment duration is usually about 6 months and typically is integrated with periodontal or advanced restorative procedures. Uprighting of teeth that have tilted into an extraction space prior to bridgework, extrusion of teeth with a subgingival fracture margin to allow placement of a coronal restoration on sound root surface and anterior alignment to facilitate the best appearance of restorative work are examples of some adjunctive treatments.

Comprehensive treatment: The aim of comprehensive treatment is to achieve the optimal aesthetic and functional occlusal result. Where the skeletal discrepancy is mild, camouflage by dento-alveolar movement is possible using fixed appliances. The principles of treatment planning and treatment follow similar lines to those adopted for class I, class II division 1 and division 2 and class III malocclusions (see Sections 10.2–4) but overbite reduction must be achieved by intrusion of incisors rather than by extrusion of molars. In those with a more marked skeletal discrepancy, a combined orthodontic and surgical approach is required to ensure that the best facial and occlusal results are achieved (see below).

Where significant periodontal breakdown has occurred, comprehensive treatment may still be possible provided disease is controlled and a regular maintenance scheme operates throughout orthodontic treatment. Because of the reduced periodontal ligament area, forces should be as light as possible, and anchorage planning is critical. Fixed appliances using a sectional arch approach are often indicated, and permanent retention with a bonded retainer is usual.

Timing of treatment: Treatment is usually deferred until growth is essentially completed, which is generally in late teens in males and slightly earlier in females. This delay is most important where growth is excessive, particularly in class III cases, as it safeguards against relapse brought about by further growth. Where the temporomandibular joint is ankylosed or the dentofacial deformity is causing severe psychological distress, earlier intervention may be considered.

Indications: Surgical–orthodontic treatment is indicated where the problem cannot be dealt with satisfactorily by orthodontics alone. This includes moderate-to-severe anteroposterior, vertical and lateral skeletal discrepancies as well as craniofacial anomalies, including cleft lip and palate.

Record analysis and planning: The patient’s cephalometric film should be traced or digitised and then a ‘standard’ skull template (e.g. Bolton standard, representing the norm) is superimposed to indicate sites of discrepancy. These templates, however, are composites for males and females. Formerly, planning involved enlargement of the photographic negative profile to match 1:1 with the cephalometric film and then ‘cutting and pasting’ to simulate the desired surgical changes.

Newer techniques allow superimposition of the patient’s soft tissue profile, from a digital photograph, on the cephalometric tracing; then, the image is adjusted in line with proposed orthodontic/surgical moves. The patient may view the predicted impact on the soft tissue profile of various ‘simulated’ treatment options, the risks and benefits of which should be explained to facilitate decision making. It should be emphasised that these ‘predictions’ are not an assurance of the likely outcome. 3D planning combining CT scans, 3D facial images with incorporation of digital models is now being refined.

Surgical movement may also be simulated on a duplicate set of dental casts. Where a maxillary procedure is planned, the casts should be mounted on a semiadjustable articulator.

The impact of presurgical decompensation, which usually worsens facial appearance, must also be understood. It may, on occasion, be helpful for a prospective patient to have an opportunity to discuss the process with another individual where a successful outcome has been achieved.

Presurgical orthodontics and at surgery: All dental and periodontal disease must be managed before treatment can get underway. Presurgical orthodontics allows the jaws to be positioned in their desired location without interference from tooth positions. This phase of treatment takes about 1 year but may be slightly longer where there is severe crowding or protrusion. It aims to align and co-ordinate the arches or arch segments as well as to establish the vertical and anteroposterior position of the incisors. Usually, this involves placing the incisors at a normal inclination to their respective bases, decompensating for any existing dento-alveolar compensation (nature’s attempt to camouflage a skeletal discrepancy). The full extent of the skeletal problem is thus revealed so maximum surgical correction can then be achieved. Intermaxillary traction for class III or II cases is often used to aid decompensation. Depending on the crowding and space requirements, extractions may be necessary to allow the tooth movements required. Consideration should also be given to removal of impacted third molars at this stage.

In some cases, it is not possible or advisable to decompensate fully for the incisor position because of anatomical constraints (e.g. a narrow symphysis or thin labial gingival tissue in a class III malocclusion). Marked gingival recession is likely in the latter if the lower incisors are proclined.

Space must be created interdentally to allow access for surgical cuts when a segmental procedure is planned. Some tooth movements (e.g. levelling of a curve of Spee in patients with a short face) are managed in a more expeditious manner postsurgically while other movements (e.g. correction of a bilateral skeletal crossbite of the upper arch) can be managed simultaneously with Le Fort I correction for other skeletal problems at the time of surgery.

When presurgical orthodontics is completed, photographic images, radiographs (including a lateral cephalometric film) and impressions should be taken. Arch co-ordination, and the other desired tooth movements, should be checked on a set of work casts. Adjustment to tooth position(s) may be necessary and, in some cases the surgical plan, may require slight amendment. Rigid rectangular stabilising archwires with ball hooks, to allow for intermaxillary fixation, should be placed. An interocclusal acrylic wafer, made from casts positioned to simulate the desired occlusal result, is recommended routinely to ensure accuracy of the postsurgical result. If maxillary or bimaxillary surgery is planned, a facebow recording is necessary to allow the casts to be positioned on a semiadjustable articulator. At surgery, the interocclusal wafer is used to locate the jaws or jaw segments accurately; these are then usually fixed semirigidly in position by either mini-plates in the maxilla or lag screws in the mandible. Intermaxillary fixation may also be required.

Maxilla:

Mandible:

Bimaxillary procedures: Correction of the skeletal problems in many individuals involves surgery to both the maxilla and mandible to produce optimal dentofacial harmony.

Distraction osteogenesis: Based on manipulation of a healing bone, this technique stretches an osteotomised site in advance of calcification to induce the generation of new bone formation and investing soft tissue. Where large distances of movement are required and/or deficient jaws increased in size at an early age, this technique has its greatest applications. The maxilla or mandible can be moved forward with distraction but it lacks the precision of standard orthognathic procedures in terms of placement of the jaws or teeth in preplanned positions. Patients with craniofacial syndromes, for example moderately severe hemifacial microsomia with a rudimentary ramus on the affected side or those with severe maxillary deficiency as found in Apert or Crouzon syndrome, are prime candidates for distraction. The mandibular symphysis may also be widened by this procedure.

Adjunctive facial procedures: To improve the soft tissue contours beyond those attainable by orthognathic surgery, several adjunctive facial procedures can be employed. These include chin augmentation, rhinoplasty, implants for facial soft tissue contours, liposuction and platysma lift procedures. Injection of collagen or Botox™ tends to produce a temporary aesthetic improvement.

Postsurgical orthodontics and follow-up: Once adequate bone healing and a satisfactory range of mandibular movement has been achieved, the wafer is removed and light round archwires placed to allow occlusal settling. Light elastic traction is used to guide the teeth into the desired position and ensure that good interdigitation is achieved so the appliances can be removed within 6 months of surgery. This is followed by a retention regimen that usually follows standard fixed appliance therapy. Surgical follow-up should be for a minimum of 2 years.

• surgical and orthodontic plans are correct and realistic, well-integrated and executed competently

• surgical movement is modest – no greater than 5–6 mm vertically or anteroposteriorly in the maxilla or 8 mm in the mandible; does not place the soft tissues under tension and the condyles are not distracted at surgery

• aberrant soft tissue factors are absent (e.g. tongue thrust or previous surgical scarring, as may occur in repaired cleft palate) and lips are competent

• teeth have been placed in soft tissue balance and not extruded presurgically

• patient is compliant with all aspects of treatment, particularly postsurgical wear of elastic traction

• fixation is adequate.

Classification: Several classification systems exist, but the cleft is easiest described as involving the primary (lip and alveolus to the incisive foramen) and/or secondary palate (hard palate from incisive foramen back and soft palate) as being unilateral or bilateral, complete or incomplete (Fig. 10.5). A submucous cleft may not be detected for some time as the overlying mucosa is unaffected, but it is usually noticed when speech development is poor.

Skeletal features:

Dental and occlusal features: On the side of the cleft, the following anomalies often exist:

Elsewhere in the mouth, tooth size tends to be smaller and eruption delayed, with a greater prevalence of hypodontia, enamel hypoplasia and abnormal tooth shape than in unaffected individuals.

A class III incisor relationship is common with a crossbite of one or both buccal segments and occasionally a lateral open bite.

Growth: Postsurgical scarring in those with cleft lip and palate restricts anteroposterior, vertical and transverse growth of the midface. These changes do not seem to occur to any significant extent in unrepaired clefts.

Hearing and speech: Where the cleft involves the posterior palate, the action of tensor palati on the Eustachian tube is impaired, often leading to hearing difficulties. This, in addition to palatal fistulae and adverse palatopharyngeal function, means that speech is often defective. Regular assessment of hearing and speech is essential before and during school years.

Anomalies of other body tissues: Cardiac and digital anomalies are found in one-fifth of those with clefts and are most common in those with clefts of the secondary palate only.

Neonatal period: Maternal support, with discussion of the potential of what current treatment offers, should be provided by designated individual(s) from the cleft team. Emphasis should also be placed on the importance of a high standard of dental care for later treatment. The mother must be instructed in feeding using special bottles and teats (e.g. Rosti bottle and Gummi teat). A specialised health visitor should be available for provision of ongoing advice and support.

Repositioning of the displaced cleft segments by removable appliances, often with extraoral strapping to facilitate surgical repair (presurgical orthopaedics), is now undertaken less frequently than before owing to its dubious benefits.

Lip closure is usually undertaken at around 3 months, with the Millard technique (often with modifications) adopted most commonly. The extent of alar cartilage dissection and the simulataneous use of the vomer flap are disputed. In bilateral clefts, both sides are now mostly repaired together but doing each side separately is still practised in some centres. Repair of the hard and soft palate is usually carried out between 9 and 12 months, most commonly by means of a von Langenbeck procedure. Delaying until at least 5 years, as practiced in some European centres, is inadvisable due to the detrimental effects on speech development.

Primary dentition: Preventive advice including dietary counselling and possibly provision of fluoride supplements is essential. Speech should be assessed formally at about 18 months and speech and hearing assessed regularly. Speech therapy can be instituted as necessary. Pharyngoplasty and/or lip revision may be required prior to starting school.

Mixed/permanent dentition: In preparation for alveolar bone grafting at 9–10 years of age, upper incisor(s) alignment and arch expansion is usually undertaken to facilitate access. Extraction of any primary teeth in the upper arch should take place at least 3 weeks prior to surgery to allow healing. Bone is harvested from the iliac crest or the chin, placed in the cleft site and the wound closed with keratinised flaps. The graft, in addition to allowing eruption of the permanent canine and space closure, supports the alar base and helps to close oronasal fistulae; in bilateral cases, it also stabilizes the premaxilla.

Once the permanent canine has erupted (~10–15% require exposure), further treatment usually involves centreline correction and space closure by mesial movement of the buccal segment teeth so that the canine replaces a missing or diminutive lateral incisor. The treatment plan should be finalised with input from a restorative colleague. Crowding should be relieved in the non-cleft quadrant if necessary and in the lower arch if orthodontic correction of the malocclusion is likely. Otherwise, lower arch extractions should be delayed until surgical correction of the malocclusion is planned.

Where gross midface retrusion is present in late teenage years, a Le Fort I or II surgical advancement is likely, with possible mandibular setback and/or genioplasty depending on the severity of the skeletal problem. Presurgical orthodontics proceeds along conventional lines (see Section 10.6). Rhinoplasty may be required as a later procedure to optimise the facial profile.

Retention: Because of scar tissue in the cleft area, treatment where maxillary arch expansion has been undertaken has a high relapse potential, so long-term retention is necessary in these cases.

    a. Affects the upper permanent lateral incisors in 20% of cases

    b. Affects lower second premolars more so than upper second premolars

    c. Is more common in males than females

    d. Has not a familial link

    e. Of third molars can be determined definitively by 8 years of age

    a. Occur in about 10% of the population

    b. Are more common in females than males

    c. May occur in the lower incisor area

    d. May cause spacing of 1/1

    e. May have no effect on the dentition or occlusion

    a. Is advisable when the bifurcation of the is calcifying, to maximise the potential for spontaneous correction of malocclusion in that quadrant

    b. Should be compensated

    c. Should be balanced

    d. Is likely to lead to overjet increase

    e. Is likely to lead to 3 mm overbite increase

    a. To allow spontaneous correction of potential crossbite on erupting 2s

    b. To allow space to be created for an unerupted upper central incisor whose eruption has been inhibited by the presence of a supernumerary

    c. To allow the lower incisors to drop lingually in a developing class III malocclusion

    d. To encourage improvement in the position of a displaced 3

    e. Along with bs in early mixed dentition to encourage space closure in children in whom 2s are absent

    a. Is described as balanced when extraction of the upper left first primary molar is requested also

    b. Is described as compensated when extraction of the lower left first primary molar is requested also

    c. Should be compensated to prevent a centreline shift

    d. Should be balanced to prevent overbite reduction

    e. Should be requested if the crown of the tooth is submerged level with the gingival margin

    a. An increased overbite

    b. An asymmetric increase in overjet

    c. A buccal segment crossbite

    d. An adaptive tongue thrust

    e. Upper incisor root resorption

    a. Crowding in the arch

    b. Retention of c/

    c. An increased overbite

    d. Early loss of lower primary molars

    e. Absent 2/

    a. Represents inclination of the upper/lower incisors less than the mean for Caucasians

    b. Is common in Caucasians

    c. Results when lip pressure is higher than tongue pressure

    d. May exist with incisor relationship class I

    e. Has a high chance of stability when corrected

    a. A persistent thumb-sucking habit

    b. Upper arch crowding

    c. A bilateral buccal segment crossbite

    d. An anterior mandibular growth rotation

    e. Proclination of the lower incisors

    a. The underlying anteroposterior skeletal pattern is class I

    b. There is a backward pattern of mandibular growth

    c. The lower lip lies under the upper incisors post-treatment

    d. A thumb-sucking habit persists

    e. A buccal segment crossbite is present pretreatment

    a. Works by maintaining the mandible in its rest position

    b. Is least effective during active growth

    c. Is ideal for treating irregularities in tooth alignment

    d. Requires 14–16 hours per day wear to be effective

    e. Requires post-treatment retention until growth has ceased

    a. A reduced interincisal angle

    b. A high lower lip line

    c. Normal cingulum thickness on the upper incisors

    d. A forward pattern of mandibular growth

    e. Early loss of a mandibular primary first molar

    a. A short maxillary length

    b. A more posterior position of the glenoid fossa

    c. A reduced mandibular length

    d. A more protrusive position of the maxilla

    e. Retroclined lower incisors

    a. A low Frankfort mandibular planes angle

    b. An endogenous tongue thrust

    c. A cleft of the lip and alveolus

    d. A digit-sucking habit

    e. A horizontal pattern of facial growth

    a. Early loss of e/

    b. Submergence of

    c. A repaired cleft palate

    d. A prolonged thumb-sucking habit

    e. A class III malocclusion

    a. Overbite reduction is generally easier than in an adolescent

    b. Molar extrusion is the approach of choice for overbite reduction orthodontically

    c. Lighter forces are desirable for tooth movement if the dentition is periodontally compromised

    d. Anchorage demands may be less if teeth have been lost

    e. Significant skeletal discrepancies may be addressed by growth modification

    a. Mandibular advancement greater than 8 mm

    b. Condylar distraction during surgery

    c. Adequate fixation

    d. Poor co-operation with wear of intermaxillary elastics

    e. Tongue thrust

    a. Enamel hypoplasia of /1

    b. Delayed eruption of the permanent dentition

    c. Absent /2

    d. A lingual crossbite of the buccal segments

    e. Anterior crossbite

    a. Is best undertaken before age 8 years

    b. Improves alar base support

    c. Provides bone through which 6 can usually erupt

    d. Stabilises a mobile premaxilla in a bilateral cleft

    e. Should be undertaken simultaneously with any extractions on the cleft side

1. Removal of lower second primary molars after eruption of the permanent lateral incisors.

2. Early removal of the associated upper primary canine.

3. Retention of a lower second primary molar.

4. Observe but take no specific action.

5. Removal of supernumerary.

6. Carry out a balancing extraction.

7. Extraction of the same tooth type in contralateral quadrants.

8. Autotransplant a lower premolar.

9. Prescribe a radiograph to check if a supernumerary tooth is present.

    10. Upper permanent incisor proclination with an upper removable appliance.

    11. Fit an upper removable appliance space maintainer.

    12. Extraction of the upper left second primary molar.

    13. Prescribe a dental panoramic tomogram and an upper anterior occlusal radiograph.

a. A 9-year-old boy with class I incisor and molar relationships who has large carious lesions in the upper left and lower right first permanent molars (all permanent teeth are developing on a dental panoramic tomogram).

b. A 10-year-old girl with a class II division 2 malocclusion where the upper right permanent canine is not palpable buccally; subsequent radiographic assessment reveals the tooth to overlap less than half the width of the upper right permanent lateral incisor and to be located at the mid-third of its root; the long axis of the unerupted right maxillary canine is <30° to the midsagittal plane.

c. An 18-year-old girl with a class III malocclusion and generalised mild crowding who is not keen to proceed with fixed appliance orthodontic treatment; a single conicle supernumerary is identified radiographically well above the apices of the upper incisors.

d. A 9-year-old boy with the upper permanent incisors fully erupted and a median diastema of 4 mm.

e. An 8.5-year-old girl presents with caries on the medial aspect of the upper left first permanent molar which is impacted into the upper left second primary molar producing resorption of half the width of its distobuccal root resulting in pain.

1. What are the causes of an upper median diastema in an 8-year-old?

2. What are the management options?

1. What are the possible causes of the open bite?

2. What treatment options may be considered?

1. What is the possible aetiology of the crossbite?

2. When is early treatment advisable?

3. What factors must be considered regarding treatment possibilities?

4. List the desirable features in the design of an upper removable appliance to correct the incisor relationship.

1. What features are visible?

2. What other common factors or conditions may produce a similar effect?

3. How would you manage the case?

1. What anomaly is visible?

2. What is its likely aetiology?

3. What are the management options?

4. What factors would dictate your decision regarding treatment?

1. What occlusal anomaly is visible?

2. What clinical assessment would you wish to perform and why?

3. What is the possible aetiology?

4. What are the treatment options?

1. What anomaly is visible?

2. What factors may account for this?

3. How would you aid localisation?

4. What interceptive method may have helped to avoid this problem developing?

5. What factors determine whether orthodontic alignment is possible?

1. What anomaly is present?

2. How may this arise?

3. What advice would you give?

4. What management possibilities exist?

1. What obvious facial anomaly is present?

2. What investigation is shown in Figure 10.12? What does this show?

3. What occlusal features would you expect?

4. How would you manage the patient?

1. Classify the cleft and outline the anatomical aetiology.

2. What would be the initial management (first weeks)?

3. When would surgical intervention usually be considered?

4. What would be your management during the primary dentition?

• missing or small upper lateral incisors

• generalised spacing in the upper arch

• proclination of the upper incisors in a class II division 1 malocclusion or digit sucking

• supernumerary tooth, i.e. mesiodens

• low-lying frenal attachment may be associated with a midline space; blanching of the incisive papilla when the frenum is put under tension and a characteristic ‘V’-shaped notch radiographically in the alveolar bone between the incisors implicate involvement of the frenum.

• activation: individual Z-springs may be used to procline each of the incisors (or one double-cantilever spring to procline both) but activation may displace the base plate away from the palate; use of a screw section clasping the teeth to be moved will overcome this problem

• retention: typically Adams’ clasps on 6/6; (if a screw section is used to procline the incisors, these may be clasped also)

• anchorage: from all teeth other than 1/1, and the palate contacted via the base plate

• base plate: posterior capping is necessary to disengage the anterior teeth by about 2 mm, thereby facilitating crossbite correction.