The Treatment Of Adult Skeletal Class â…¢ Malocclusion With Presurgical-orthodontic

Objective: To discuss the clinical effects of pre-surgical orthodontic treatment ofskeletal class Ⅲmalocclusion in adults.Method: An adult male patient was selected from the stomatology department of thesecond affiliated hospital of Dalian Medical University in Nov2009. The patient had askeletal class Ⅲmalocclusion with mandibular prognathism. The molar and canine were inclass Ⅲrelationship with an anterior crossbite of1mm reverse overjet. There was a slightcurve of spee and a lower midline shift of2mm to the right. From the frontal view the facewas symmetrical and proportional in the midface region. Laterally, the profile was concavewith excessive mandibular growth. The case was planned for a combinedsurgical-orthodontic treatment. Upper maxillary first premolars were extracted while noextraction was done in the mandibular arch. Pre-surgical orthodontic treatment involvedsequential space closure in the upper arch by canine retraction followed by en mass anteriorsegment retraction with closing loops. In the lower arch, decompensation of the loweranterior segment was done by labially inclining the incisors. Post-surgical orthodontictreatment involved only correction of occlusion and intercuspal relationship with triangularelastics. Superimposition of cephalometric headfilms was done to evaluate the treatmentchange.Results: The treatment course lasted35months in total. In comparison:(1) SNA,Po-NaPerp.did not change, SNB changed from88°to83°, Po-NaPerp. changed from14mmto9mm, Co-Gn changed from151mm to144mm, ANB from-4°to1°，Wits appraisal from-10mm to-2mm, FMA decreased by2°, and ANS-Me decreased by4mm,（Ba-N）-（Ptm-Gn）changed from3°to-1°that meant the sagital relationship of jaws changed fromclass Ⅲto class I, and mandibular counterclockwise rotation occurred.(2) U1-SN changedfrom116°to108°，U1-NA changed from32.5°to24°, U1-NA decreased by3mm, however, IMPA increased from70°to79°, this indicated that the lingual compensation of the lowerincisors due to the increased jaw size was decompensated.(3) Soft tissue profile changedtowards a more esthetic face following treatment, with soft tissue pogonion movingbackward and E-line retruding in a clockwise direction. ULP, ULEP increased slightly,nasolabial anle from76°to83°, facial convexity angle from6°to11°, LL-EP decreased.The patient was satisfied with the treatment.Conclusion:(1) For skeletal class Ⅲmalolccusion in adults, combined surgical orthodontictreatment can result in a better occlusal relationship and jaw relation, regain oral function,and improve profile, which cannot be obtained by surgery or orthodontic treatment if doneindividually only.(2) Pre-orthodontic treatment should be based on the surgical goals, sothat de-compensation be planned first by correction of occlusal relationship, thenpositioning the jaw ideally by surgical means.