Australasian Dentist Issue 89

Category 62 AustrAlAsiAn Dentist O ral and maxillofacial deformities (OMDF) are characterized as irregularities or malformations in the bones and/or soft tissues of the mouth, jaws, and face. it has been reported that about 20% of the world’s population have some major oral and maxillofacial deformity. Orthognathic surgery can eliminate severe aesthetic and functional deformities and can be a life-changing event for a patient. An orthodontist’s role in orthognathic surgery can be divided into several phases and at each of these phases, collaboration between the orthodontist, general dentist and the surgeon is critical. together an orthodontist, surgeon and dentist can improve the quality of life of a patient both physically and psychosocially. Introduction Dentofacial deformities are characterized by disharmony among the face and dental bone structures, that have a negative impacts on facial aesthetics, stomatognathic function and mental health of a person. 1,2 Although several treatments have been suggested but orthognathic surgery combined with orthodontic treatment is considered the gold standard for correction of moderate- to-severe deformities. 3 Orthognathic surgery refers to surgical correction of the maxilla that involves proper alignment and positioning of the bones and teeth relative to the base of the skull. Combined with orthodontic treatment, orthognathic surgery provides adequate correction of malocclusion, especially for patients diagnosed with a dentofacial deformity. 4 (Fig 1) An orthodontist’s role in orthognathic surgery can be divided into several phases starting from the initial evaluation to pre- surgical orthodontics, surgical planning, and finally postsurgical orthodontics. 5 Initial evaluation the goal of the initial evaluation is to define the skeletal deformity. this is done by careful collection and analysis of orthodontic records along with a thorough clinical evaluation. the minimum orthodontic records required for proper evaluation of a prospective orthognathic patient are standard orthodontic photographs, articulated or appropriately trimmed study models, a panoramic radiograph, a lateral cephalogram, and a posteroanterior cephalogram. Additional records that can provide critical information include three-dimensional (3D) photographic images, 3D cone beam radiographs and video images of the patient. 6,7,8 Accuracy and consistency with standardized photos and radiographs are essential in the acquisition of these records. Once these records are collected, they need to be analysed and organised in a meaningful manner. some of the critical points that have to be kept in mind when analysing orthodontic records in preparation for orthognathic surgery are. i. the Posterior transverse dimensions: Mandibularskeletal,mandibulardental and maxillary dental discrepancies are to be identified and any dental compensations either corrected on diagnostic casts or estimated on the original study models, and any remaining transverse discrepancy between maxilla and mandible must be due to a skeletal imbalance in the transverse dimension of the maxilla. Assuming the orthognathic patient is at the age of skeletal maturity, this maxillary transverse deficiency can be corrected through surgically Assisted rapid Palatal expansion (sArPe),(Fig 2), orthodontic dental compensation, or a multipiece leFort osteotomy. 5 ii. the Vertical and the sagittal discrepancy: these are best appreciated by utilising a good cephalometric analysis. For the sagittal discrepancy Orthodontics and orthognathic surgery lInICal Dr Geoff Hall By Geoffrey Hall Fig 1: Dentofacial deformities are characterized by disharmony among the face and dental bone structures. The picture above is preoperative and postoperative image of the same person following orthognathic surgery. Fig 2: Maxillary skeletal discrepancy can be eliminated through surgically assisted rapid palatal expansion (SARPE) Fig 3: Vertical and the sagittal dimensions are best appreciated by cephalometric analysis using the ANB (A point, Nasion and B point) angle Fig 4: Wits appraisal should be used to cross check the sagitta discrepancy by taking into account the rotation of the laws