- Symmetric facial deformity
- The cleft patient
- Orthognathic surgery
- Asymmetric facial deformity
Facial deformity may be the result of a variety of different causes including congenital disease such as cleft lip and palate, developmental abnormality, trauma and infection. Deformity may also occur either as the direct result of a neoplastic disease or by its treatment, either with surgery or radiotherapy.
Very occasionally deformity may occur with other acquired conditions that may affect facial growth such as juvenile rheumatoid arthritis (Still’s disease), or it may occur after growth has ceased as with Paget’s disease or other disturbances of bone metabolism such as fibrous dysplasia.
It is also important to remember that the face is comprised of both hard and soft tissue elements, and that deformity may derive from either element, but very often one will impact on the other.
There is an obvious variation in facial form that gives us our individuality and ethnicity. Individuals who fall outside this acceptable range of variation may suffer from being labelled as either unattractive or ugly. This may cause the individual difficulties in social and sexual relationships and may deny certain employment opportunities. More severe facial deformity may cause social exclusion and can be associated with psychological problems.
This chapter aims to deal with the commoner types of facial deformity resulting from jaw growth disharmony, which often presents as malocclusion. The term ‘dentofacial’ deformity may be used to describe this problem. These problems usually result in symmetric facial deformity and are treated jointly by the maxillofacial surgeon and orthodontist.
The commoner conditions resulting from a disease process are also addressed, such as cleft deformity. Asymmetric facial deformity may result from conditions such as hemifacial microsomia and condylar hyperplasia. Again collaboration between surgeon and orthodontist is required.
Assessment of Facial Deformity
The patient may identify problems as:
- functional – difficulties associated with the bite, inability to chew or achieve incisor contact
- aesthetic – problems of their appearance as perceived by them, although some patients may be embarrassed to discuss this.
Patients are often referred by orthodontists who are unable to treat the underlying skeletal jaw disproportion by orthodontic means alone.
The patient is first examined by evaluation of the facial form, both from the profile and full face. It is helpful to divide the face into thirds (see Chapter 14). A full intraoral examination should include the state of the dentition as well as assessment of the occlusion. Poor dental health and hygiene are usually a contraindication to orthognathic surgery.
This includes a full radiographic assessment of the dentition, including impacted and buried teeth, associated pathology including caries and periodontal problems. The lateral cephalostat provides invaluable information for both the surgeon and orthodontist to aid in diagnosis and treatment planning.
Study models should always be available at the joint consultation; anatomically articulated models are used in the surgical planning.
Photographic records are extremely helpful in treatment planning as well as providing a clinical record. They should include both the face in profile and viewed from the front. Intraorally the occlusion should be shown from both sides and the front, and all photographs should be standardised and of good quality.
In some patients further information may be required, both as part of the diagnosis and in planning treatment. Patients with asymmetric deformity may require special scans; these are discussed below in the relevant section.
Symmetric facial deformity may be diagnosed and classified according to the facial types shown below. This classification is useful in prescribing the correct form of surgical correction to maximise successful and stable outcomes.
Symmetric Facial Deformity
The following is a useful classification of symmetric dentofacial deformity.
- Type A. Class III malocclusion due to either a large mandible or small maxilla (or both). The vertical height of the face is not increased. Treatment may involve moving the mandible posteriorly or the maxilla anteriorly (or both) (Figure 18.1).
- Type B. Class III malocclusion with an anterior open bite. This is due to either a large mandible or a small maxilla (or both). The vertical height of the face is increased. Treatment will always involve superior repositioning of the maxilla to reduce the increased vertical face height, together with posterior repositioning of the mandible (Figure 18.2).
- Type C. Class II malocclusion with a deep overbite. This is due to a small mandible. The lower vertical face height is decreased. Treatment involves a mandibular advancement (Figure 18.3).
- Type D. Class II malocclusion with an anterior open bite. This is caused by an increased vertical growth of the maxilla in a downward direction. The mandible is of a normal size but has been rotated downwards and backwards by clockwise rotation due to the excess downward growth of the maxilla. Treatment involves superior repositioning of the maxilla, following which the mandible autorotates anticlockwise to become normally positioned in relation to the face, and comes into a normal class I occlusion (Figure 18.4).
- Type E. Class II with an anterior open bite. This is similar to Type D; however, the mandible is small and the surgical correction requires a mandibular advancement together with superior repositioning of the maxilla (Figure 18.5).