Neuromuscular diagnosis in orthodontics: effects of TENS on the sagittal maxillo-mandibular relationship.

AIM

This study was conducted in order to assess the changes in the occlusal position of the mandible after ULF (Ultra Low Frequency)-TENS relaxing procedure in subjects in pubertal growth phase with diagnosed Angle Class II division 1 and mandibular dentoalveolar retrusion.

MATERIALS AND METHODS

This study was performed on 19 patients (13 females, 6 males) with an Angle Class II division 1, aged between 10 and 15 years old (mean age 12.26, SD 1.32), characterised by mandible dentoalveolar retrusion and optimal vertical facial dimension, diagnosed by clinical and cephalometric evaluation. Diagnostic neuromuscular registrations were made for all subjects. The casts were mounted on articulator in habitual intercuspal position with a tooth-guided wax bite registration. Reference points were chosen at molar level. Subsequently the same casts were mounted in myocentric position and compared to the habitual intercuspal position, assessing the sagittal shift after TENS procedure.

STATISTICS

Mean and standard deviation were calculated on the amount of shifting at the left molar reference point after TENS procedure. Analysis of variance (ANOVA), using STATA statistics package, was carried out in order to evaluate the influence of sex and age on the amount of molar shift.

RESULTS

Nine subjects showed, in the sagittal plane, a forward mandibular shift in neuromuscular myocentric position compared to habitual intercuspal position. Six subjects showed no differences between habitual and myocentric position in the sagittal plane. Four individuals showed a backward mandible shift after TENS indicating worsening of the II molar class in the sagittal plane.

CONCLUSION

This study suggests that TENS recorded occlusion in subjects with Class II division 1 with mandible dentoalveolar retrusion allows to visualise an unusual trend of growth. The advancements of the mandible were not taken into account. These results could offer new diagnosis and prognosis methods for Class II malocclusions.