[Use of PAR index to evaluate the treatment outcome for Class II division 1 malocclusion with different tooth extraction patterns]

Abstract

Purpose: To assess the outcome of orthodontic treatment for Class II division 1 malocclusion with different tooth extraction patterns using PAR index.

Methods: PAR index was applied on pre- and post-orthodontic treatment cast for 64 Class II division 1 malocclusion patients with two different tooth extraction patterns: extraction of maxillary teeth only (Group 1), and extraction of maxillary and mandibular teeth(Group 2). SPSS 10.0 software package was used for Student's t test.

Results: The PAR index of group 1 and group 2 pre-orthodontic treatment was 36.21+/-6.82 and 38.34+/-7.51. There were no significant difference (P>0.05) between the two groups. The PAR index of group 1 and group 2 post-orthodontic treatment was 6.13+/-1.64 and 5.89+/-1.75. There were no significant difference (P>0.05) between the two groups. The decrement and the rate of reduction of group 1 was 30.05+/-7.43 and 85.33%+/-5.68%. The decrement and the rate of reduction of group 2 was 32.38+/-8.12 and 87.47%+/-5.21%. The occlusal relationship improved significantly in the two groups after treatment.

Conclusions: Treatment for Class II division 1 malocclusion with different extraction patterns can both acquire satisfactory results.