Longitudinal evaluation of jaw muscle activity and mandibular kinematics in young patients with Class II malocclusion treated with the Teuscher activator

Mj Cuevas,Ja Alarcon,A Cacho,C Martin

doi:10.4317/medoral.18610

Abstract

Objectives: A longitudinal study was performed to evaluate the jaw muscle activity and mandibular kinematics after Teuscher activator treatment and at 2 years after orthodontic treatment completion. Material and Methods: Twenty-seven children with Class II division 1 malocclusion were evaluated before treatment (T0; mean: 11.6 years), after functional treatment (T1; mean: 12.8 years), and 2 years after orthodontic treatment (T2; mean: 18 years). Bilateral surface electromyographic activities of the anterior temporalis, posterior temporalis, masseter, and suprahyoid muscle areas were analyzed at rest and during clenching, swallowing, and mastication. Kinematic recordings of the mandibular maximum opening, lateral shift, right and left lateral excursions, and protrusion were evaluated. Results: Compared to T0, the left masseter activity during clenching was decreased at T1 but increased at T2, similar to the other evaluated muscles. The suprahyoid activity during swallowing was increased at T1 but decreased at T2. The masseter activity during mastication was increased at T1 and further increased at T2. The left and right lateral excursions and protrusion did not show significant changes throughout the experiment. Conclusions: Teuscher activator and subsequent fixed orthodontic treatment improved jaw muscle function; however, a long period was needed to attain complete neuromuscular adaptation. Key words:Class II malocclusion, jaw muscles, mandibular kinematics, sEMG, Teuscher activator.

Highlights

Angle Class II division 1 malocclusion, which has a high prevalence among different populations, is a very common problem encountered by orthodontists [1,2,3,4].Myofunctional alterations, such as reductions in the functional and postural activities of the jaw muscles, have been described in affected patients [5,6]
The reproducibility of surface electromyographic (sEMG) recordings was assessed from repeated measurements (4 trials) from different subjects performed over different days
We observed significant increases in the resting sEMG activities of the anterior temporalis (AT), posterior temporalis (PT), and MA areas and a significant decrease in the activity of the SH area from the end of treatment completion to the end of the observation period (T1-T2)

Summary

Introduction

Angle Class II division 1 malocclusion, which has a high prevalence among different populations, is a very common problem encountered by orthodontists [1,2,3,4] Myofunctional alterations, such as reductions in the functional and postural activities of the jaw muscles, have been described in affected patients [5,6]. The aim of this prospective, longitudinal, case-series study was to evaluate the sEMG activities of masticatory muscles and the kinematics of mandibular changes in children with Class II division 1 malocclusion treated by the Teuscher activator combined with high-pull headgear after functional treatment and at 2 years after orthodontic treatment completion

Objectives

Results

Discussion

Conclusion