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

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ABSTRACT

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.

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.

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