Influence of occlusal stabilization splints and soft occlusal splints on the electromyographic pattern, in basal state and at the end of six weeks treatment in patients with bruxism.

The aim of this study is to assess the electrical activity generated in temporal and masseter muscles during voluntary muscular contraction of patients with bruxism, as a result of the use of two types of occlusal splints (occlusal stabilization splint and soft occlusal splint) in which 2 groups of 8 patients were evaluated -12 women and four men aged 19 to 40 years, who used a single type of occlusal splint for 46 to 60 days. The splints were made from sheets of rigid acetate plus heat-cured acrylic (occlusal stabilization splint, control group) and sheets of flexible acetate (soft occlusal splint, experimental group). Two electromyographic tests (EMG) were performed on each patient; one before placing the splint and another at the end of the treatment. The statistical analysis used was computerized variance ANOVA analysis with F distribution (P < or = 0.025). In the control group, muscle electrical activity increased significantly in 5 patients and decreased slightly in 3. In the experimental group, there was considerable reduction of such activity in 6 patients and a slight increase in 2. There is a statistically significant difference (P < or = 0.025) between the muscle electrical activity generated in the control group and in the experimental group. The increase in muscle electrical activity in the control group may have been due to a neuromuscular recovery process; while the decrease in the experimental group might have been due to a negative or decremental process of muscular organization to prevent the recruitment of new motor units. Occlusal stabilization splints are therefore considered better than soft occlusal splints.