Background:
Dysfunction of the masticatory muscle group occurs in all types of masticatory system pathology. This is sometimes associated with changes in the musculoskeletal system, which are manifested in hypertension and hypotonia of the masticatory group of muscles, that cause a decrease in occlusal height.

Material and methods:
There were 123 patients enrolled, aged 35-54 years, who were made temporary fixed, fiberglass-reinforced plastic prostheses for the upper or lower jaw. There are several methods to improve the quality of orthopedic treatment with fixed bridges with reduced occlusal height, considering the condition of the masticatory muscles. One is the use of temporary fixed structures that provide a gradual increase in occlusal height, allow muscles to adapt to new conditions, and promote restructuring of “usual” myostatic reflexes.

Results:
To examine the effect of fixed structures on the m. masseter and m. temporalis, a technology for the manufacture of advanced temporary bridges was developed. This allowed us to study the process of masticatory muscle group adaptation to fixed orthopedic structures kept on the abutment teeth of patients without fractures for 6 months. In addition, it was possible to prepare the dental and maxillofacial system for permanent orthopedic treatment.

Conclusions:
Determination of the average total values of m. masseter and m. temporalis allowed us to establish the most effective intervention for patients with reduced occlusion height before, 1 month, and 6 months after temporary orthopedic treatment. There was a tendency for patients of all groups to approach the absolute symmetry.