The skeletal class III, malocclusion has characteristics determinants as the bad relationship between the bone bases, may be due to a deficiency in the developing maxillar, excessive mandibular growth, or a combination of both. The treatment for these types of malocluções is orthognathic surgery where the surgeon and the orthodontist must work together for improves aesthetics and functional of patients. The objectives of this study are 1) to evaluate the cephalometric changes resulting from treatment of orthognathic surgery in patients with skeletal class III malocclusion. 2) Assess the characteristics electromyographic muscle during jaw movements of chewing and isometric contraction of mastication muscle (the anterior temporal and masseter) bilaterally. In the assessment of electromyographic features the following variables will be considered: root mean square standardized and not standardized and linear envelope. 3) Compare the symmetrical variation of temporal and masseter muscles in different jaw movements (isotonic and isometric) before and after orthognathic surgery in patients with skeletal class III malocclusion. 4) Association between electromyography and variation cephalometric 5) Association between pain symptom and variation cephalometric. Will be selected 20 volunteers who underwent orthognathic surgery for mandibular setback, the technique of sagittal osteotomy of the mandibular branches and maxillary advancement (Lefort I). The cephalometric radiographs to be obtained in two periods before surgery (1 to 3 days before = T0rx) and after surgery (6 and 12 months, T1rx and T2rx respectively). To be assessed electromyography the electrical signals into two periods: before surgery (2 to 3 months = T0 emg) and after (6 and 12 months, T1emg and T2emg respectively). Painful symptoms will be assessed by questionnaire RDC (Reseach Diagnostic Criteria) axis I, administered before (T0) and after surgery (T2) orthognathic surgery. This study will apply descriptive statistics to calculate the arithmetic means and standard deviations, minimum and maximum values of each of the cephalometric measurements and electromyographic evaluations before and after surgery. The normality of the data will be verified by the Shapiro-Wilks. If the data presented normal distribution, is applied to analysis of variance with repeated measures for the appropriate comparisons with the Tukey test as post-hoc multiple comparisons of cephalometric and electromyographic measures in different periods. For the correlation analysis between EMG and the cephalometric measurements will be used Pearson correlation coefficient. To analyze the association between EMG pain symptoms will be used chi-square or Fisher exact test. If the data are not normally distributed and will be processed after failing to achieve a normal distribution nonparametric tests are applied. All analysis will be performed using SAS software with the probability of type I error set at a level of 5% (p <0.05).
News published in Agência FAPESP Newsletter about the scholarship: