Abstract:

Skeletal class Ⅱ malocclusion is characterized by maxillary protrusion， mandibular retrognathia， or a combination of both， and often accompanied by vertical dimensional discrepancies； treatment is complex， and combined orthodontic-orthognathic surgery is needed for the adult patients. Clear aligner therapy has gradually been applied in complex orthodontic cases. However， limited cases have been reported domestically and internationally regarding the application of clear aligner therapy combined with orthognathic surgery. This article presented a case of a patient with skeletal class Ⅱ high-angle malocclusion treated with the combined therapy and analyzed the clinical efficacy of the treatment appraoch to provide reference for the clinical practice. Extraction of impacted wisdom teeth 18， 28， 38， and 48， as well as orthodontic teeth 15， 25， 34， and 44， was performed in stages before orthodontic treatment. Clear aligner therapy was used for preoperative orthodontics. In sagittal plane， a super-complete class Ⅱ canine and molar relationship and a 13-14 mm overjet of the anterior teeth were established. The maxillary and mandibular arch morphology was matched horizontally. The orthognathic surgery included maxillary LeFort Ⅰ osteotomy， bilateral sagittal split ramus osteotomy （BSSRO） and chinplasty. Fine occlusal adjustment was conducted after operation. After treatment， the skeletal relationship between upper and lower jaw was corrected to normal； subspinale-nasion-supramental angle （ANB） was improved from 12.3° to 4.7°； the patient established the class Ⅰ canine and molar relationship， with normal overjet and overbite； root parallelism was good and there was no obvious root resorption； the facial soft tissue profile was significantly improved， and nasion-subnasale-pogonion angle（N-Sn-Pg） was improved from 143.9° to 162.8°. The curative effect was stable 1 year after operation. Clear aligner therapy can efficiently complete combined orthodontic and orthodontic surgery in the complex cases. Compared with the fixed appliance， it is more beneficial to the patients’ need for beauty and the maintenance of periodontal health.

Key words: Combined orthodontic and orthognathic surgery, Skeletal class Ⅱ malocclusion, Clear aligner therapy, High angle malocclusion, Case report