Orthodontic-surgical treatment: neuromuscular evaluation in skeletal Class II and Class III patients

Aim: This study aimed at evaluation the neuromuscular response in patients undergoing orthodontic-surgical treatment. The patient sample was divided subsamples, based on skeletal class. Material and methods: All of the patients who underwent orthognathic surgery in the Department of Orthodontics of Fondazione IRCCS Cà Grande (University of Milan) were subjected to periodic electromyographic evaluation of the masticatory muscles (masseter and anterior temporal muscles) and electrokinesiographic evaluation of the mandibular movements (maximum opening, protrusive movement, and lateral movement). The sample consisted of 80 patients (37 males and 43 females) at the end of growth. The electromyographic instruments used in the study included a Freely electromyograph and a K6-I electromyograph. Statical evaluation was carried out with the Student’s t-test for independent samples. Result and conclusions: Analysis of the data obtained revealed significant differences between patients with skeletal Class II and those with skeletal Class III. In the early stages of treatment, muscle activity was greater in Class II patients than in Class III patients. However, this difference was reversed at the end of treatment. A similar difference was found in mandibular kinesiology: at the beginning of treatment, maximum mandibular opening movement was greater in patients with skeletal Class II than in those with skeletal Class III. At the end of treatment, this difference was eliminated. At the beginning of treatment, Class II patients showed greater mandibular protrusive movement than Class III patients. At the end of treatment, this gap was reduced without being reversed. No statistically significant differences between the Class II and Class III patients groups were seen for the mandibular right or left lateral movements. Functional evaluation in patients in surgical orthodontic therapy is an important element in the diagnostic-therapeutic recordings, so as to reduce as much as possible any incorrect neuromuscular activity that can result in relapse.