[Fibre-type differences in masseter muscle of Beagle dogs with implanted functional appliance therapy].

Purpose: To observe the changes of MyHC-I expression in masseter muscle of Beagle dogs with implanted functional appliance therapy，and to investigate the adaptive remodeling of masticatory muscle.

Methods: Eight, seven-month-old, male Beagle dogs were randomly assigned to experimental group and control group and were killed at 4,8,12 weeks during treatment and 4 weeks after the appliance removed(16 weeks). Serial cross-sections of superficial masseter muscle were cut and stained with MyHC-I antibodies.SPSS11.5 software package was used for statistical analysis.

Results: The positive expression rate of MyHC-I was 7.61% in the control group, and 20.43% in the experimental groups at 4 weeks﹙P<0.01﹚. The amount of type I fibres reached to peak at 8 weeks. With increase of treatment time, the amount of type I fibres gradually reduced. At 16 weeks, the amount of type I fibres was similar to the control groups.

Conclusions: The expression of MyHC-I is significantly changed in masseter muscles of Beagle dogs with implanted functional appliance therapy. Implanted functional appliance forward mandibular displacement therapy can obviously promote the adaptive remodeling of masticatory muscle.