[Using Coben analysis to evaluate the therapeutic effect of maxillary protraction on maxillary maldevelopment].

OBJECTIVE: We aims to evaluate the therapeutic effect of maxillary protraction on maxillary maldevelopment using Coben analysis to illustrate the advantages of Coben analysis in identifying pathogenic mechanisms and in designing treatment plans for Class III malocclusions. METHODS: A total of 120 patients were diagnosed to have skeletal Class I maloc- clusions with maxillary maldevelopment. These patients were selected as the subjects of the present research. Maxillary protraction was exerted to promote maxilla growth. Cephalometric analysis was conducted by using Coben analysis and angle analyses of Beijing Medical University to collect data before and after maxillary protraction. RESULTS: According to Coben analysis measurements, the height of facies cranii increased after maxillary protraction. The depth of lower face decreased, whereas that of mid-face increased and the Ptm-A value increased significantly in the mid-face (P < 0.001). In the angle ana- lysis of Beijing Medical University, SNA, ANB, U1/NA, U1/SN, MP/SN, and Y-axis angles increased significantly (P < 0.001), whereas SNB, U1/L1 (P < 0.001), and L1/MP (P < 0.05) decreased. CONCLUSION: Maxillary protraction has a significant effect on growing skeletal Class III malocclusions withthe chief mechanism of Ptm-A value just diagnosed as minor by Coben analysis. Coben analysis is visual and clear in identifying pathogenic mechanisms of Class III malocclusions.