Abstract:

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 Ⅲ malocclusions 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 analysis 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 with the 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.

Key words: cephalometric analysis, Coben analysis, maxillary maldevelopment, maxillary protraction