An adult female patient with a chronological age of 19 years and 4 months and an ectomorphic body type reported to the Department of Orthodontics, Pushpagiri College of Dental Sciences, with the chief concern of unattractive facial appearance due to forwardly placed lower jaw and teeth. (Figures 1-4). Her parents pointed out that she was greatly dissatisfied by her looks. There was no relevant familial history pertaining to skeletal Class III malocclusion, nor any pertinent medical history.
Extraoral clinical examination in frontal view exhibits the patient's face to be leptoprosopic (oval); paranasal areas were deficient; lips were potentially incompetent with excessive lower lip vermilion exposure, and facial asymmetry was evident with the lower border of mandible moderately shifted to the right. Her growth pattern was predominantly vertical and there was increased incisor and gingival visibility at smile. Examination of vertical facial proportions (Figure 2) revealed that both her midfacial and lower anterior facial heights were increased which corroborates an increased display of teeth and gingiva. Lateral view and oblique view showed pronounced mandibular prognathism, with a concave profile, an acute nasolabial angle, an everted and hypotonic lower lip, reduced labiomental fold, a long chin-throat length with a well-defined inferior border of the mandible, and an acute lip-chin-throat angle.
Intraorally, the molar relationship was Class III with a complete anterior crossbite, along with a reverse overjet of 2 mm (Figure 3). There was generalized interdental spacing amongst her anterior teeth and the incisors were flared, combined with an anterior open bite. These characteristics may point to a large tongue. A lower dental midline discrepancy was present due to mandibular shift to the right. She had recently undergone endodontic treatment for her lower left first molar.
Pretreatment radiographic records included lateral and posteroanterior (PA) cephalograms and orthopantomogram (OPG) (Figures 5-6). Cephalometric analysis (Table 1) revealed a Class III skeletal base with mandibular prognathism, increased maxillary skeletal and dental height, increased vertical chin height, and upper anterior proclination with compensatory lower anterior retroclination.
After a joint clinic discussion with the Department of Oral and Maxillofacial Surgery, Pushpagiri College of Dental Sciences, Le Fort I maxillary impaction in combination with mandibular setback by bilateral sagittal split osteotomy (BSSO), with presurgical and postsurgical orthodontics, was planned in order to achieve facial aesthetics and a functionally optimum occlusion. During BSSO an asymmetrical setback with more orientation to the left was planned in order to correct the shift of the lower jaw and midline. Vertical reduction genioplasty for correction of the chin was considered, subjected to the changes, at the time of surgery or as a secondary procedure. Lower lip augmentation to reduce the thickness and vermillion display along with rhinoplasty later was planned, if needed, after thorough posttreatment evaluation. Therapeutic extractions of all third molars were to be done prior to surgery.
After initial restorative and prophylactic measures, presurgical orthodontics was begun with 0.022'' x 0.028'' Roth preadjusted edgewise prescription appliance. Intra-arch levelling and aligning were achieved, and spaces were consolidated in both the arches. To achieve sufficient decompensation and ideal maxillary incisor inclination therapeutic extractions of upper first premolars were done, which was followed by controlled retraction of maxillary anterior segment with loop mechanics. Maxillary and mandibular arches were aligned up to 0.021'' x 0.025'' stainless steel wire and arch compatibility was established between upper and lower arches (Figures 7, 8, 9, and 10). In due course upper and lower third molars were extracted to facilitate the orthognathic surgery. At the end of the presurgical phase radiographic records were repeated and compared (Figures 11 and 12).
In order to assess the practical considerations and further predict the results of the planned surgical approach, cephalometric prediction tracing was done both manually using the template method and with computer image prediction. In template method, skeletal profiles of maxilla and mandible were traced on an acetate paper. Profile tracing was then duplicated and transferred to a thin cardboard. This outline was then cut to produce a cardboard template. From these templates, trial sections were made until desirable location and amount for osteotomy were found. The cut sections of both maxilla and mandible were then fitted back to the tracing in desired occlusal relation. Finally, soft tissue outline can be traced in regard to the reference ratios, and the probable postsurgical changes were checked. Later, computer-based analysis was done wherein cephalometric landmarks were digitized and the surgical repositioning was monitorized. Measurements, calculations, and analyses were performed using Facad (Ilexis AB, Sweden). The obtained data was incorporated into prediction algorithms to provide single-line profile drawings predicting the final treatment goal (Figure 13). In the Maxilla, a 5 mm of superior repositioning along with an advancement of about 3 mm, was sufficient enough to reduce the gingival show and improve the para-nasal hollowing. In Mandible, 8 mm of setback brought about good posterior intercuspation with an aesthetically pleasing profile.
Cast prediction or model surgery and fabrication of occlusal splints for use at surgery were the next steps in the planning sequence. Since both jaws were to be repositioned, the maxillary and mandibular dental casts were mounted on a semiadjustable articulator with the aid of facebow transfer (Figure 14(a)) and bite registration taken with the patient's jaws in the retruded contact position or centric relation. Model simulation of the anticipated surgical movement was performed next. The individual dental casts were repositioned, simulating the movements of the jaws as depicted by the manual and digital prediction. An intermediate acrylic occlusal splint was fabricated after the maxillary cast was repositioned on the articulator (Figure 14(b)). The mandibular cast was then repositioned to oppose the maxillary cast, simulating the final position of the jaws at surgery. Based on this position the final occlusal splint was then fabricated (Figure 14(c)).