| The purpose of this study was to gather longitudinal data to quantify and describe the pain experience (intensity and quality) and rates of tooth movement during controlled human tooth movement, specifically where stresses are changed from relatively light (4 kPa) to heavy (52 kPa) and heavy to light. In a split mouth design, maxillary first premolars were extracted, posterior anchorage appliances were placed, and canines distalized using custom vertical loops activated by nickel titanium springs calibrated to deliver 4 or 52 kPa. Subjects were seen for 11 visits over 84 days. The study period was split into 4 phases: Day -35 to Day 0, Day 1 to Day 3, Day 7 to Day 35, and Day 42 to Day 84. Subjects were blinded to the stress levels and at each study visit completed a validated pain report for right and left canines consisting of the Visual Analogue Scale and the Modified McGill Pain Questionnaire Short Form designed for orthodontic subjects, plus had maxillary impressions made for analysis of tooth movement. For a given stress, Friedman and Wilcoxon Signed Ranks tests were used to evaluate for significant effects of phase on pain score. After testing for equal variances, two independent t-tests were employed to investigate whether or not there were significant differences between teeth moved by 4 versus 52 kPa for Visual Analogue Scale (VAS) and rate of Orthodontic Tooth Movement (OTM). Pearson Correlation analyses determined relations between VAS and rate of OTM by phases.;Subjects reported slightly elevated pain associated with canines moved by 52 kPa compared to 4 kPa during Phase 2, however, there were no statistically significant (p = 0.279) differences in pain intensities and qualities between the two levels of controlled stresses. In Phase 4, teeth exposed to 52 kPa moved on average at higher rates of movement than teeth exposed to 4 kPa. However, these rate differences were not statistically significant. There were no significant correlations between subject reported pain responses and rates of tooth movement. |
