Comparison of the dental arch changes in patients with different malocclusions.

Aims and Objectives: To evaluate the pre-treatment and post-treatment dental arch changes in both upper and lower arches in orthodontic patients treated with extraction of first premolar teeth. Subjects and Methods: Measurements were made on casts of 50 post treated cases in the age group of 12-30 years for individual tooth measurements, width of the arches (inter-incisal, inter-canine, inter-premolar and inter-molar) arch length (both right and left sides, anterior segment, posterior segment and total arch length for both for the maxillary and mandibular dental casts. Statistical Analysis Used: Kolmogorov-Smirnov test for Normality, Regression Analysis was done as variables were tested and proved to follow normality. Statistical software  Statistical Package for the Social Sciences version 18 (SPSS Inc.; Chicago, Illinois, USA) was used for data analysis. Descriptive statistics and paired t-tests were used to compare the changes in the Class I and Class II div 1 groups. Results: There was a significant increase in the inter-incisor and inter-canine width post-treatment in the Class I and Class II div 1 subjects in the upper arch but no significant change in inter-incisor width in the lower arch in class I subjects. A significant decline in the inter-molar arch width in both the groups were seen. The inter-premolar arch width declined significantly in Class I cases while it increased significantly in Class II div 1 subjects. There was a significant increase in anterior arch length and a significant decrease in posterior arch length in all subjects. Conclusions: The findings of this original clinical research should significantly help the orthodontists in orthodontic treatment planning in patients requiring extractions of premolars.