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Objective@#To evaluate the clinical efficacy of invisible orthodontic appliances without brackets for the distal movement of maxillary molars to improve the ability of orthodontists to predict treatment outcomes.@*Methods@#Web of Science, Cochrane Library, Embase, PubMed, Wanfang Database, CNKI Database, and VIP Database were searched for studies investigating the efficacy of invisible orthodontic appliances for distal movement of maxillary molars in adult patients and published from database inception to August 1, 2023. A total of three researchers screened the studies and evaluated their quality and conducted a meta-analysis of those that met quality standards.@*Results@#This study included 13 pre- and postcontrol trials with a total sample size of 281 patients. The meta-analysis revealed no significant differences in the sagittal or vertical parameters of the jawbone after treatment when compared with those before treatment (P>0.05). The displacement of the first molar was MD=-2.34, 95% CI (-2.83, -1.85); the displacement was MD=-0.95, 95% CI (-1.34, -0.56); and the inclination was MD=-2.51, 95% CI (-3.56, -1.46). There was a statistically significant difference in the change in sagittal, vertical, and axial tilt of the first molar before and after treatment. After treatment, the average adduction distance of the incisors was MD=-0.82, 95% CI (-1.54, -0.09), and the decrease in lip inclination was MD=-1.61, 95% CI (-2.86, -0.36); these values were significantly different from those before treatment (P<0.05).@*Conclusion@#Invisible orthodontic appliances can effectively move the upper molars in a distal direction and control the vertical position of the molars. When the molars move further away, there is some degree of compression and distal tilt movement, which is beneficial for patients with high angles. The sagittal movement of incisors is beneficial for improving the patient's profile.
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Objective: To compare the difference of the first molar and alveolar morphology between the deviated side and non-deviated side in skeletal class III patients with mandibular deviation by using cone-beam computed tomography (CBCT) image combined with three-dimensional reconstruction measurement technology. Methods: Fifty-six asymmetric CBCT data were evaluated by Mimics 10.0 and 3-Matic software. Some measures were analyzed by t-test including the buccolingual angle, the mesiodistal angle, crown root ratio of first molar and the thickness of alveolar or cancellous bone. Results: The buccolingual angle and crown root ratio of mandibular first molar were significantly larger on the deviated side than on the non-deviated side (P=0.021, P=0.004). Compared with the non-deviated side, the buccal and total cancellous bone thickness of mandibular first molar were significantly smaller on the deviated side (P=0.043, P=0.048). There was no significant difference in the ratio of buccal and total cancellous bone thickness on mandibular first molar (both P=0.118). The measurements of maxillary first molar and maxillary alveolar bone morphology were not significantly different between two sides (all P>0.05). Conclusion: In skeletal class III patients with mandibular deviation, although the buccolingual compensation of first molar is found, the position of first molar in the alveolar bone is symmetrical. The asymmetry of alveolar bone morphology are mainly manifested in the reduction of the buccal and total cancellous bone thickness on the mandibular deviated side.
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Objective·To compare the difference of the first molar and alveolar morphology between the deviated side and non-deviated side in skeletal class Ⅲ patients with mandibular deviation by using cone-beam computed tomography (CBCT) image combined with three-dimensional reconstruction measurement technology. Methods·Fifty-six asymmetric CBCT data were evaluated by Mimics 10.0 and 3-Matic software. Some measures were analyzed by t-test including the buccolingual angle, the mesiodistal angle, crown root ratio of first molar and the thickness of alveolar or cancellous bone. Results·The buccolingual angle and crown root ratio of mandibular first molar were significantly larger on the deviated side than on the non-deviated side (P=0.021, P=0.004). Compared with the non-deviated side, the buccal and total cancellous bone thickness of mandibular first molar were significantly smaller on the deviated side (P=0.043, P=0.048). There was no significant difference in the ratio of buccal and total cancellous bone thickness on mandibular first molar (both P=0.118). The measurements of maxillary first molar and maxillary alveolar bone morphology were not significantly different between two sides (all P>0.05). Conclusion·In skeletal class Ⅲ patients with mandibular deviation, although the buccolingual compensation of first molar is found, the position of first molar in the alveolar bone is symmetrical. The asymmetry of alveolar bone morphology are mainly manifested in the reduction of the buccal and total cancellous bone thickness on the mandibular deviated side.
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Objective:To evaluate the therapeutic effects of orthodontic therapy with mandibular first molar extraction.Methods:77 cases of malocclusion were divided into 3 groups:Bilateral mandibular first premolar extraction group(A,30 cases),unilateral man-dibular first molar extraction group(B,27cases)and bilateral mandibular first molar extraction group(C,20 cases).The OGS indexes were measured before and after orthodontic treatment and statistically analysed.Results:Remarkable occlusal improvement was seen in all three groups after treatment(P0.05).OGS indexes among the three groups after treatment were significantly different(P<0.05).The improvement in group A was more significant than that in group C(P<0.01)and the improvement in group C was more significant than that in group B(P<0.01). Conclusion:Orthodontic therapy with bilateral mandibular first molar extraction is effective in orthodontic treatment of malocclusion, but is not as effective as that with bilateral mandibular first premolar extraction.