Does orthodontic treatment provide a real functional improvement? a case control study

BACKGROUND Electromyographic analysis of the masticatory muscles provides useful data on the behavior of these muscles during stomatognathic system functioning and allows a functional assessment of orthodontic treatments. This study was undertaken to verify if achieving an Angle Class I bite through orthodontic treatment can lead to neuromuscular balance. METHODS This study enrolled 30 patients (20 females, 10 males, mean age: 15.78 years) with an Angle Class II, division 1 malocclusion that was orthodontically treated. A group of 30 subjects (19 females, 11 males; mean age: 16.15 years), randomly selected among subjects with an Angle Class II, division 1 malocclusion that had not been orthodontically treated served as the Control group. Both groups were subjected to electromyography to study their neuromuscular characteristics. The Shapiro-Wilk's test revealed a non normal distribution, therefore we used a Friedman two way ANOVA by ranks test to compare differences of surface electromyography values between treated and untreated subjects at closed and open eyes condition. RESULTS A statistically significant interaction between orthodontic treatment and open eyes conditions was detected for anterior temporal muscles. A significant imbalance of the anterior temporal muscles, which is indicative of an asymmetric electromyographic pattern, was also found. CONCLUSIONS The present data indicate that achieving a correct occlusal target does not necessarily correspond to a neuromuscular balance.