Comparison of the dental arch changes in patients with different malocclusions

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.

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.

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.

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.

The findings of this original clinical research should significantly help the orthodontists in orthodontic treatment planning in patients requiring extractions of premolars.