Maxillofacial characteristics affecting chin deviation between mandibular retrusion and prognathism patients

Abstract

Objective: To examine and compare the maxillofacial characteristics affecting chin deviation threedimensionally in facial asymmetry patients with mandibular retrusion and mandibular prognathism. Materials and Methods: Maxillofacial computed tomography (CT) scan data were obtained from 48 orthognathic surgery patients (24 cases of mandibular retrusion and 24 cases of mandibular prognathism) with facial asymmetry. Although chin deviation was assessed on the basis of the ANS-to-menton line on frontal cephalograms, its contributing factors were evaluated on threedimensional CT images. Maxillary height, ramus length, frontal ramal inclination, lateral ramal inclination, mandibular body length, and body height were defined on each side, and right-left differences were calculated and analyzed. Results: In an assessment of chin deviation, subjects in this study showed predominantly left side deviation regardless of the group, and the degree of menton deviation did not reveal significant differences between groups. In a comparison of right-left differences in contributing factors, all values were noted to be greater in the retrusion group, except for body height, which showed no difference between chin-deviated and contralateral sides. In particular, ramus length presented a statistically significant difference between the two groups. Conclusion: Based on the same degree of chin deviation in mandibular prognathism and retrusion in this study, results of right-left differences in contributing factors indicate that chin deviations are expressed easily in mandibular prognathism, whereas they occur only with significant right-left differences in relevant maxillofacial structures in individuals with mandibular retrusion. (Angle Orthod. 2011;81:988-993.)

Use of spherical coordinates to evaluate three-dimensional facial changes after orthognathic surgery

“…In the 3D analysis of facial asymmetry, the linear distances and angles among structures are commonly used 14,15,16,17. A spherical coordinate system can be modified to analyze facial lines.…”

3D analysis and clinical applications of CBCT images

“…54 Bayome et al 27 reported that the ramus length demonstrated a significant moderate negative correlation with the gonial angle (r ¼ À0.62). This might suggest that the longer the ramus the smaller its angle with the mandibular body.…”

Fasi̇yal Asi̇metri̇

“…56 Son yıllarda 3 boyutlu bilgisayarlı tomografi ve 3 boyutlu fotoğraf gibi yeni teknikler de kullanılmak-tadır. [63][64][65][66] CBCT gibi üç boyutlu görüntülemeler distorsiyon olmadan asimetrilerin doğru teşhisini sağlar. Belirgin mandibuler asimetrisi olan vakalarda, CBCT asimetrinin şiddetini belirleme imkanı sağlar.…”

“…Belirgin mandibuler asimetrisi olan vakalarda, CBCT asimetrinin şiddetini belirleme imkanı sağlar. [66][67][68][69] Yumuşak doku fasiyal asimetri teşhisinde hızlı ve etkili 3 boyutlu görüntüleme teknikleri de tanıtılmıştır.…”