[Clinical effect of cortical incision with rapid maxillary expansion to assist orthodontic-orthognathic treatment of skeletal Class Ⅲ malocclusion].

PURPOSE: To investigate the clinical effect of rapid maxillary expansion with cortical osteotomy combined with orthodontic- orthognathic treatment for skeletal Class Ⅲ malocclusion. METHODS: A total of 84 patients with skeletal Class Ⅲ malocclusion admitted to Jining Dental Hospital from March 2018 to May 2020 were randomly divided into experimental group and control group, with 42 cases in each group. The control group was treated with orthodontic-orthognathic treatment, while the experimental group was treated with orthodontic-orthognathic treatment with rapid maxillary arch expansion by cortical incision. The time of closing gap, alignment time, maxillary first molar and maxillary central incisor tooth movement distance in the sagittal direction were compared between the two groups. Before treatment and 4 weeks after treatment, the vertical distance from the end of the upper central incisor edge to the horizontal plane(U1I-HP), the distance from the apex of the upper central incisor to the coronal plane(U1I-CP), the vertical distance from the edge of the upper pressure groove to the coronal plane(Sd-CP), the vertical distance from the upper alveolar seat point to the horizontal plane(A-HP), the vertical distance from the point of the upper lip to the coronal plane(Ls-CP), and the vertical distance from the inferior point of nose to coronal plane(Sn-CP) were measured, and the relevant changes were calculated. During the treatment period, the complications of the two groups were compared. SPSS 20.0 software package was used for statistical analysis of the data. RESULTS: There was no significant difference in alignment time, A-HP change, Sn-CP change, maxillary first molar movement distance and maxillary central incisor movement distance between the two groups (P＞0.05). The closing interval in the experimental group was significantly shorter than that of the control group (P＜0.05). The changes of U1I-HP, U1I-CP, Sd-CP, and Ls-CP in the experimental group were significantly higher than those in the control group (P＜0.05). There was no significant difference in the incidence of complications between the two groups during treatment (P＞0.05). CONCLUSIONS: Rapid maxillary expansion of cortical incision assisted orthodontic-orthognathic treatment of skeletal Class Ⅲ malocclusion patients can shorten the closing gap time and improve the treatment effect, which has no obvious influence on the sagittal direction of the teeth.