Effects of spring-loaded posterior bite-block appliance on masticatory muscles

The effects of spring-loaded posterior bite-blocks on masticatory muscles w ere investigated to evaluate the correlation between masticatory muscles an d craniofacial form in long-faced children. The appliance was used in 10 su bjects (6 girls and 4 boys) with a chronological mean age of 10.40 +/- 1.12 years for the treatment of skeletal anterior open bite. Electromyographic activity of the anterior and posterior temporal and masseter muscles was re corded before and after treatment during postural position, maximal biting, chewing, swallowing, postural position with the appliance in the mouth, an d maximal biting with the appliance in the mouth. After treatment, increase s in SNB and overbite (P < .05, P < .001, respectively) and decreases in AN B, SNGoAr, and overjet parameters were found to be statistically significan t (P < .05, P < .01). When the measurements related to muscle activity were examined, increases in anterior temporal postural (P < .05), anterior temp oral chewing (P < .01), masseter chewing (P < .05), posterior temporal chew ing (P < .05), and masseter swallowing (P < .01) were found to be statistic ally significant. A positive correlation was found between ANB and anterior temporal postural and a negative correlation between SNGoAr and masseter s wallowing. The increase in muscle activities was considered to occur as a r esult of the appliance used.