Ultrasound evaluation of functional orthopedic treatment's effects on masseter muscle in class ii maloclusion patients with mandibular retrognathia

The aim of this study is to analyze the changes during functional treatments. The masseter muscles of 40 patients were analyzed by ultrasound. It was clinically observed if there were any pain and/or spasm in TMJ and masticatory muscles due to mandibular movements. 30 patients were chosen: 15 from fixed, 15 from removable functional groups. 10 patients with the same indication were also chosen from clinic archive as control group. The patient was followed up for six months. Three records were taken at the beginning of treatment (T0), at the third month (T1) and at the end (T2). Mandibular movement was measured by examining their masticatory muscles and TMJs. Synchronously, the length and thickness of masseter muscles were measured by ultrasound. While a meaningful decreasing was observed in masseter muscle thickness in functional orthopedic treatment between T0 and T1, it was found it got thicker again between T1 and T2, but it couldn't come to its starting values. While there was a meaningful elongation in masseter muscle between T0 and T1, its length was unchanged between T1 and T2 but it was longer in comparison to starting condition. No meaningful muscle sensitivity was observed in masticatory muscles. It was determined removable functional appliances more restrained the lateral mandibular movement than the fixed appliances. It was observed functional treatments meaningfully increased interincisal distance but they decreased protrusive movement in mandibula. In conclusion, it is considered that both fixed and removable functional orthopedic treatments affect the masseter muscle and mandibular movements.