Stereophotogrammetric evaluation of tooth-induced labial protrusion.

PURPOSE: To better manage dental treatment outcome, a previsualization of desired appearances can be used to understand patients' wishes. A deeper comprehension of labial modifications related to hard-tissue movements is advantageous. The purpose of the study was to evaluate tooth restoration-induced labial displacements in three dimensions. MATERIALS AND METHODS: In a group of 20 healthy Caucasian individuals, simulations of vestibular translations of maxillary anterior crowns were obtained by placing an acrylic resin veneer on the labial surfaces of maxillary incisors and canines. Three-dimensional stereophotogrammetric acquisitions were made to evaluate soft-tissue changes induced by the simulations. Linear dislocation of selected landmarks and labial surfaces were quantified using dedicated software. RESULTS: All paired and two midline labial landmarks had significant displacements, ranging from 13% (Subnasale landmark) to 103% (left Cheilion landmark) of veneer thickness (2 mm thick). A significant positive correlation was obtained between the lower lip displacement and overjet values. CONCLUSIONS: The vestibular shift of maxillary incisors and canines affect both upper and lower vermilion areas, without involving cutaneous perilabial landmarks.

Low level laser therapy as an adjunctive technique in the management of temporomandibular disorders.

The purpose of this study was to assess the effect of low level laser therapy on subjects with intra-articular temporomandibular disorders (IA-TMD), and to quantify and compare severity of signs and symptoms before, during, and after the laser applications. The sample consisted of 45 subjects randomly divided into three groups (G) of 15 subjects each: G-I: 15 individuals with IA-TMD submitted to an energy dose of 52.5 J/cm2; G-II: dose of 105.0 J/cm2; and G-III: placebo group (0 J/cm2). In all groups, the applications were performed on condylar points on the masseter and anterior temporalis muscles. Two weekly sessions were held for five weeks, totaling 10 applications. The assessed variables were: mandibular movements and painful symptoms evoked by muscle palpation. These variables were measured before starting the study, then immediately after the first, fifth, and tenth laser application, and finally, 32 days after completing the applications. The results showed that there were statistically significant differences for G-I and G-II at the level of 1% between the doses, as well as between assessments. Therefore, it was concluded that the use of low level laser increased the mean mandibular range of motion and reduced painful symptoms in the groups that received effective treatment, which did not occur in the placebo group.

Electromyographic evaluation of neuromuscular coordination of subject after orthodontic intervention.

The aim of this work was to investigate the neuromuscular changes associated with the orthodontic post-treatment using surface electromyography. One hundred (100) young, healthy adults without signs and symptoms of temporomandibular dysfunction (TMD) were divided into two groups: 60 subjects who were undergoing orthodontic intervention (Ortho Group) and 40 subjects who had no orthodontic intervention (Control Group), aged 18-25 years. EMG activity of masseter and temporalis anterior muscle was recorded during two different tests: 1. maximum voluntary clench (MVC) with cotton rolls; and 2. MVC in intercuspal position. In all subjects, both tests were performed with symmetric muscular patterns (more than 85%) and with insignificant latero-deviating of the mandible (lower than 10%). There are no statistically significant differences between the subjects of both groups evaluated. Both groups showed medium index values calculated according to the normal standards established previously.

Are the bite force and electromyographic activity altered in muscle TMD patients with abfraction lesions?

OBJECTIVE: To verify if the maximal molar bite force (BF) and the electromyographic activity (EMG) are altered in TMD patients with abfraction lesions (AL) when compared to those without AL. METHODS: The sample was composed of 45 patients (18-60 years old), 30 diagnosed with TMD (RDC/TMD) (15 with AL and 15 without AL) and 15 controls. The BF and the EMG of the masticatory muscles (maximal voluntary contraction (MVC) and chewing gum) were measured. RESULTS: TMD patients showed decreased BF (p < 0.001), without differences between patients with and without AL. The electromyographic activity during MVC was similar among all groups (p > 0.05), although there was a greater trend of muscular balance for the control group (percentage overlapping coefficient and electromyographic indexes). The TMD group without AL showed a lower number of cycles and masticatory frequency. DISCUSSION: TMD patients with and without AL exhibited similar results in the analysis of the BF and EMG, without differences.