Effect of orthodontically induced pain on velocities of mandibular movement

Orthodontic pain can decrease the muscular activity in EMG studies. Changes
in masseter muscle activity during orthodontic treatment are probably caused by
discomfort, pain, or alterations in the occlusal relationship via tooth movement. The purpose of this study was to determine the extent of the effect of orthodontic pain on the velocities of mandibular movements. Thirty subjects were observed by using the K-6 model Myotonics kinesiograph for the measurement of jaw motion velocities before and after insertion of orthodontic posterior separators on the first, second, third, fifth days, and fifth day immediately after separator removal. Five consecutive opening-closing strokes were recorded and processed to evaluate the following parameters: 1) maximal opening and closing velocities, 2) average opening and closing velocities, and 3) maximal terminal velocity before tooth contact. Measurements of orthodontic pain were evaluated by using visual analogue scale (VAS) . The average velocity of 5 consecutive mandibular movement strokes on the 5 days were compared with the VAS score of pain by using the Pearson correlation statistic model. Neither the opening velocity nor the closing velocity was affected after separator insertion. In conclusion, mandibular movement velocities were not affected by orthodontic posterior separators.