Pain quality and intensity during tooth translation by two stresses

Pain is common during orthodontic treatment yet little is known about pain experiences with respect to magnitude of tooth loads. Objectives: The purpose of this pilot study was to assess longitudinally pain intensity and quality using a validated self-report. 

Methods: Eight subjects (five males, 3 females) who required maxillary first premolar extractions had maxillary canines retracted segmentally for 84 days using 4 kPa of stress on one side and 78 kPa on the other.  Each subject scored the McGill Pain Questionnaire-Short Form modified for orthodontic patients (MMPQ-SF), Visual Analogue Scale (VAS), and Present Pain Intensity (PPI) for both sides 13 times encompassing 4 phases: baseline, post-placement of separators, early and later tooth-loading. Pain intensity and quality were investigated: over time for differential effects of stress and gender using mixed effects regression models and by treatment phase using single factor repeated measures ANOVA and Fisher-Hayter post-hoc tests.

Results: Time significantly affected pain scores (p=0.0001); in general, reported pain peaked at Day 1 after load initiation, decreasing with time thereafter. Pain intensity (MMPQ-SF, VAS, PPI) and generalized/emotional subscale scores showed no significant differences between stresses (p>0.05) but localized subscale scores were significantly higher for 78 kPa compared to 4 kPa sides (p=0.011).  Females reported significantly higher VAS (p=0.024) and PPI (p=0.001) compared to males.  Also, significantly higher MMPQ-SF and localized subscale scores (all p≤0.023) were found for post-placement of separators and early tooth-loading compared to baseline.

Conclusions:  During tooth translation, significant differences in pain intensity and quality were found over time; however only localized pain quality was different for loads of 4 versus 78 kPa and only pain intensity showed gender differences. Funded in part by the American Association of Orthodontists Foundation.