Analysis of electromyographic indexes of temporal and masticatory muscles in patients with distal occlusion complicated by dental crowding.

OBJECTIVE: Introduction: Rate of distal occlusion (up to 40%) and dental crowding (up to 65%) is the largest in the structure of orthodontic pathology. The aim of the study was to investigate bioelectrical activity of temporal and masticatory muscles and to set parameters of electromyographic indexes in patients with distal occlusion and dental crowding in permanent occlusion.

PATIENTS AND METHODS: Materials and methods: Bioelectrical activity of temporal and masticatory muscles in 11 patients aged 16-24 years was determined before orthodontic treatment. Distal occlusion complicated by severe degree of dental crowding was revealed in this group of patients. These patients comprised the treatment group. The control group consisted of 10 subjects (mean age 21,3 ± 1,25 years) with physiological occlusion.

RESULTS: Results: It was found that functional state of temporal and masticatory muscles in patients with distal occlusion complicated by dental crowding changes during permanent dentition. It was determined that in clenching state, according to ACTIV index, temporal muscles are more active, due to the lack of activity of masticatory muscles (ACTIV =-20,73% ± 8,01%). Moreover it is worthy of notice, that functional muscle symmetry (index SIM TА/MМ) at rest in presence of distal occlusion is lower than in subjects with physiological occlusion (p <0,05).

CONCLUSION: Conclusions: According to index АCTIV TА/MМ it was established the dominance of temporal muscle activity due to lack of activity of masticatory muscles in patients with distal occlusion complicated by dental crowding and it was determined lower overall muscle symmetry index than in individuals with physiological occlusion.