CBCT Analysis of Changes in Dental Occlusion and Temporomandibular Joints before and after MEAW Orthotherapy in Patients with Nonlow Angle of Skeletal Class III

Abstract

This study focus on the changes of the position and morphology of jaw and condyle after MEAW (the multiloop edgewise arch wire) treatment in adults with a nonlow angle (mean angle or high angle SN−MP>27°) of skeletal class III (mild to moderate skeletal classs III means −5°<ANB<0°) malocclusions measured by CBCT (cone beam computed tomography). Twenty adult patients (aged 17-26) with a nonlow angle of skeletal class III malocclusions were selected in this study taken orthodontic treatment by MEAW. CBCT was taken before and after the treatment to analyze the changes of the jaw and condyle. After treatment, the angle of L7-MP decreased 12.2°, L6-MP decreased 10.5°, L1-MP decreased 8.8° (P<0.001 for each) and U1-SN increased (P<0.05). There was no significant changes between anterior and posterior APDI index and between anterior and posterior spaces of the TMJ (temporomandibular joint) (P>0.05). The linear ratio of the TMJ was the LR>12 before treatment, while it was −12<LR<12 after treatment; however, there was no statistically significant difference between them (P>0.05). There was also no significant change in anterior and posterior position and morphology of the condyle within the joint fossa after the treatment by MEAW in this study. MEAW technology in correcting the class III with nonlow angle patients mainly relies on the compensation of distally and posterior mandibular teeth, rather than the mandible and condyle moving backward to establish a neutral occlusal. This study was approved by the institutional ethics committee of the Second Hospital of Tianjin Medical University (No. KYJJ2013002).

Three-dimensional morphologic changes in the temporomandibular joint in asymptomatic patients who undergo orthodontic treatment: A systematic review

“…The 13 articles in this review were published between 2014 and 2020. Ten were prospective [24][25][26][27][28][29][30][31][32][33] and 3 were retrospective studies. [34][35][36] Five of the prospective studies were controlled, [26][27][28]30,32 and 5 were not controlled.…”

“…[34][35][36] Five of the prospective studies were controlled, [26][27][28]30,32 and 5 were not controlled. 24,25,29,31,33 One of the retrospective studies was controlled, 35 whereas 2 were not controlled. 34,36 The numbers of subjects in the research ranged from 14 to 76.…”

“…25,32 Aside from removable functional appliances, 3 studies used the Herbst appliance. [33][34][35] Finally, 1 study used the conventional fixed appliances with Multi-Loop Edgewise Archwires (MEAW), 29 whereas the remaining 2 used a mandibular advancement component with or without conventional fixed appliances. 28,31 Mean treatment length varied from 6 to 17.5 months, with ranges from 6 to 34 months.…”

“…28,31 Mean treatment length varied from 6 to 17.5 months, with ranges from 6 to 34 months. Regarding the type of diagnostic assessment used, 8 out of the 13 articles used CBCT, [27][28][29][30][33][34][35][36] 4 used MRI, 25,26,31,32 and 1 used CT. 24 The characteristics of the studies included are summarized in Table III.…”

“…Eleven of the studies were nonrandomized, 24,[26][27][28][29][30][31][33][34][35][36] so the ROBINS-I risk assessment tool was used accordingly. Two of the studies were randomized, 25,32 so the RoB 2 risk assessment was used.…”