Dynamics of Electromyography Results in Patients with Dentition Defects Before and After Restoration of Borders and Congruence of Removable Structures Bases

Abstract

Annotation. Partial tooth absence is a common pathology that often requires dental care. Contraindications to fixed dentures make removable dentures relevant, but their use has disadvantages, particularly uneven distribution of chewing pressure, which reduces chewing efficiency. Studies show that with traditional prosthetics, the bioelectrical potentials of the masticatory muscles do not reach normal values, and the force of contractions decreases with the number of missing teeth, which increases the urgency of the problem with a small number of teeth.
Aim: compare the results of the functional state of the masticatory muscles in patients using partial removable dentures before and after restoration of the boundaries and congruence of their bases.
Results. The study involved 67 patients with partial edentulousness who had removable dentures to replace defects in the dentition: 37—upper jaw, 30—lower. The tone of the masticatory muscles was assessed during a year of using the dentures, followed by clinical reassessment. The results indicated that patients of the first group had better muscle symmetry (POC temp 78–81%, POC mas 75–82%), but the lowest total activity of the masticatory muscles (1250 mV/sec). The most remarkable asymmetry was observed in the second group (POC temp 72–77%, POC mas 59–64%). In all groups, the activity of the temporalis muscles prevailed over the masseter muscles, especially in the first group (Attiv –13 – –15 %). The lateral tension index was the highest in the second (Tors 18–21%) and third (Tors 17–20%) groups, and in the first group it was within the normal range (8–10%). The total muscle biopotential increased in all groups, but remained the lowest in the first group (1470 mV/sec), while in the third group the maximum activity was observed (1610 mV/sec).
Conclusions. The study revealed significant differences in the tone of the masticatory muscles and muscle symmetry in patients with partial edentulousness using removable dentures, depending on the class of dentition defect according to the Kennedy classification. Patients in the first group have better muscle symmetry but the lowest activity of the masticatory muscles. The most remarkable asymmetry is observed in the second group, which negatively affects the masticatory apparatus. In all groups, the activity of the temporalis muscles prevails, which may indicate dysfunction. The index of lateral tension of the mandible indicates an increased load in the second and third groups, while it is within normal limits in the first group. The increase in biopotential indicates adaptive changes in the muscles. However, the lowest values in the first group emphasize the need to monitor and optimize prosthetics to improve masticatory efficiency and reduce asymmetry.