Craniofacial Morphological Analysis in Borderline Surgery Patients with Skeletal Class Ⅲ Malocclusion

Abstract

Objective To analyse the craniofacial morphology of surgery and orthodontic camouflage(extraction) borderline patients with skeletal Class Ⅲ malocclusion,thus to provide reference in treatment planning.Methods Cephalograms of 25 patients(13 orthodontic,12 surgical) with borderline Class Ⅲ malocclusion were investigated.The ANB angles of all the patients were greater than-5° before treatment.Results Significant differences were found in Go-Me/S-N ratio,U1-L1 angle and Holdaway angle using Mann-Whitney u test.Only Holdaway angle could differentiate two grounps after stepwise discriminant analysis.The critical score was 12°.72% patients were correctly classified.Conclusion To treat borderline Class Ⅲ malocclusion,the craniofacial morphology of the length ratio of mandible,the cross angle of upper and lower incisors and the concave extent of soft profile should take thorough consideration;12° of Holdaway angle can be a preliminary indicator for surgery;the opinions of patients and clinicians toward surgery are also important.

目的探討骨性Ⅲ類錯手術與非手術邊緣病例的顱面特征,為選擇臨床治療方法提供參考。方法選擇完成治療的骨性Ⅲ類錯邊緣病例,單純正畸組13例,手術治療組12例,統計分析2組病例治療前的X線頭影測量值。結果Mann-Whitneyu檢驗顯示2組下頜骨前顱底長度比Go-Me/S-N(P=0.026)、上下頜切牙的交角U1-L1(P=0.030)、Holdaway角(P=0.026)的差異有統計學意義,逐步判別分析后僅有Holdaway角能對2組進行預測區分,區分值為12°,總判別準確率為72%。結論制定骨性Ⅲ類錯邊緣病例治療計劃時,下頜骨前顱底長度比、上下頜切牙的交角以及軟組織的凹陷度是要重點分析的顱面結構項目,小于12°的Holdaway角可以作為需手術改善軟組織側貌的初步判定指標。