Paulo Batista de Vasconcelos

Effects of low-level laser irradiation in ultrastructural morphology, and immunoexpression of VEGF and VEGFR-2 of rat masseter muscle

The present study evaluates by ultrastructural and immunohistochemical methods, the possible changes on muscular tissue affected by LLLI during a treatment, for example, in cases of temporomandibular joint disorders. Sixty male Wistar rats divided into 6 groups (n=10) received ten laser irradiations, with different energy densities (groups I-0; II-0.5; III-1.0; IV-2.5; V-5.0; and VI-20 J/cm(2)). Muscles were removed and processed for transmission electron microscopic and immunohistochemical (VEGF and VEGFR-2) analyses. Captured photomicrographs of immunohistochemistry and transmission electron microscopy were evaluated. It was observed in the irradiated muscles, mitochondria of different shapes and sizes, with increased plasticity evidenced by organelles in fusion, division and the presence of elongated structures with characteristics of mitochondria, proximity with the dilated sarcoplasmatic reticulum, suggesting organelles with large amounts of energy, and the presence of cytoplasmic protrusions in the capillaries with high dosages. All studied groups showed immunostainings for both markers (VEGF and VEGFR-2), but in general those who received higher doses also showed the markings more pronounced, suggesting dose-dependent biomodulation. It was concluded that the LLLI was able to modify the ultrastructural characteristics and immunohistochemical pattern of VEGF and VEGFR-2 in the masseter muscle of rats.

Electromyographic Activity of Masticatory Muscles in Women with Osteoporosis

The purpose of this study was to analyze the electromyographic (EMG) activity and the maximal molar bite force in women diagnosed with osteoporosis in the maxillary and mandibular regions, considering the habits and conditions that lead to development of generalized skeletal bone loss, including on face bones, can disturb the functional harmony of the stomatognathic system. Twenty-seven women with mandibular and maxillary osteoporosis and 27 healthy controls volunteered to participate in the study. A 5-channel electromyographer was used. Muscle activity was evaluated by means of EMG recordings of the masticatory musculature (masseter and temporalis muscles, bilaterally) during the following clinical conditions: rest (5 s); right and left lateral excursions (5 s); protrusion (5 s); maximal dental clenching on Parafilm (4 s) and maximal voluntary contraction (4 s). This latter clinical condition was used as the normalization factor of the sample data. It was observed that individuals with osteoporosis presented greater EMG activity when maintaining mandible posture conditions and less activity during dental clenching and when obtaining maximal molar bite force. It may be concluded that facial osteoporosis can interfere on the patterns of masticatory muscle activation and maximal bite force of the stomatognathic system.

Clinical feasibility of mandibular implant overdenture retainers submitted to immediate load.

INTRODUCTION Millions of people around the world do not have access to the benefits of osseointegration. Treatments involving oral rehabilitation with overdentures have been widely used by specialists in the oral medicine field. This is an alternative therapy for retention and stability achievement in total prosthesis with conventional treatment, and two implants are enough to establish a satisfactory overdenture. OBJECTIVE The objectives of the study were to evaluate 16 patients of both sexes, with an average age of 47.4±4 years, using electromyographic analysis of masseter and temporal muscles and analyse the increase of incisive and molar maximal bite force with their existing complete dentures and following mandibular implant overdenture therapy to assess the benefits of this treatment. MATERIALS AND METHODS For these tests, the Myosystem-BR1 electromyograph and the IDDK Kratos dynamometer were used. Statistical analysis was performed using the repeated measures test (SPSS 17.0). RESULTS A decrease in electromyographic activity during the rest, lateral and protrusion movements and increase of the maximal incisive and molar bite force after 15months with a mandibular implant overdenture was observed. CONCLUSION All the patients in this study reported a considerable improvement in the masticatory function and prostheses stability following treatment. It is possible to propose that the use of mandibular implants overdenture should become the selected treatment for totally edentulous patients to facilitate oral function and quality of life.

Influence of mandibular tori on stomatognathic system function

Objectives: To verify the influence of prominent mandibular tori on the functioning of the stomatognathic system. Methods: The participants included 40 individuals, divided into two groups: those with mandibular tori (GI group: 20 subjects) and those without mandibular tori (GII group: 20 subjects). The authors used the Myosystem-Br1 electromyography system to analyze electromyographic (EMG) activity. For muscle thickness, images of the masseter and temporalis muscles were captured using the NanoMaxx ultrasound. The maximal molar bite force was obtained by means of the Kratos digital dynamometer. Results: The EMG activity was higher in the masseter muscles in the GI group, compared with the GII group, in all clinical conditions assessed except for the mandibular at rest. In dynamic conditions, this higher EMG activity was also observed in the temporalis muscles. The GI group presented significantly less temporalis muscle thickness than seen in the GII group. The maximal bite force was significantly higher in the GI group. Conclusions: Mandibular tori promoted morphological and functional changes in the stomatognathic system.

Effect of surgical treatment of mandibular fracture: electromyographic analysis, bite force, and mandibular mobility.

Abstract This study aimed to examine individuals undergoing surgery for the treatment of the fractured mandibular angle, using bite force, mandibular mobility, and electromyographic (EMG) analysis in many different clinical conditions, after 2 months postoperatively. Bite force was recorded with a digital dynamometer, model IDDK. The EMG activity (Myosystem-Br1) included the analysis of the masseter and temporal muscles. Mandibular mobility was measured using a digital pachymeter. The subjects were divided into 3 groups: G1, mandibular angle fracture (n = 7); G2, condylar process fracture (n = 5); and G3, control (n = 12). Data were tabulated and submitted to statistical analysis using the repeated-measure test carried out over time and the Student’s t-test (P < 0.05), using the Statistical Package for the Social Sciences software, version 19 (SPSS Inc, Chicago, IL). G1 and G2 had an increase in bite force. In G1, there was a regular decrease in the EMG activity in the second postoperative month. G2 presented an irregular pattern in EMG data during the period tested. Regarding the mandibular mobility, both groups obtained amplitude of all mandibular movements with a high percentage, when compared with control. A good functional recovery was achieved by the individuals who had a mandible angle fracture or condylar process fracture, after 2 postoperative months.

Influence of age on the electromyographic fatigue threshold of the masseter and temporal muscles of healthy individuals.

During human aging, the process of decreasing organic and functional activity triggers uncertainties as to how this natural biological process, unlike one that is pathological and characterized by morphophysiological changes, acts in the stomatognathic system (Cecílio et al., 2010; Glowacka et al., 2016; Santos, Fraga, & Cardoso, 2014). Among evaluations of the muscular activities of the stomatognathic system, the analysis of physiological neuromuscular fatigue induced by sustained contractions determines the functional performance of the skeletal striated musculature in humans (Schodrowski, Seipelt, AdibiSedeh, Eienbröker, & Tackenberg, 2016). Through specific and internationally recognized methodologies such as surface electromyography, the muscle fatigue threshold can be assessed using the median frequency spectrum, in order to detect the susceptibility of the muscle to an induced physiological fatigue condition; i.e., the moment at which desired force production can no longer be maintained and contractile fatigue is observed (Halvorsen et al., 2016; Pitta, Nitsch, Machado, & de Oliveira, 2015; Svensson, Burgaard, & Schlosser, 2001; Youn, Lee, & Lee, 2016) During constant force contraction, the muscle fibers reduce shortening at a specific point, as an act of organic defense, so that functional damage does not occur in the musculature, at the point at which continuous and sustained isometric contractions occur, leading to possible changes in muscular activity, which can be detected by monitoring the median frequency spectrum change of the EMG signal (Alam et al., 2015; Politti et al., 2016). The reproduction of the spectral parameters of the electromyographic signal in the masticatory muscle can provide important information about which variables change according to established situations (González-Izal et al., 2010), but have not yet determined the developmental trajectory of normal parameters in the fatigue threshold of the masseter and temporalis muscles of healthy individuals. Therefore, the primary objective of this study was to determine the fatigue threshold of the masseter and temporalis muscles by mean median frequency of the electromyographic signal during development and aging. A secondary objective was to analyze intergroup differences in the fatigue threshold by electromyographic signal of the masseter and temporalis muscles. Establishing these parameters in individuals aged between 7 and 80 years is of great scientific value, because it provides health professionals who work with movements of the human body comparisons between the healthy organism and one in which there are pathological changes, such as muscular myopathies and atrophies, and generates further advancement in the research on muscle fatigue thresholds.

Functional analysis of the stomatognathic system in individuals infected with human immunodeficiency virus.

PURPOSE To understand the effects of HIV type 1 on the function of the masticatory muscles. METHODS Sixty individuals were selected from both genders, aged between 22 and 57years (mean 36.77±9.33years), and divided into two groups: Group HIVG, 30 individuals with HIV subtype 1, and Group CG, 30 healthy individuals (control group). The individuals were submitted to assessments of their masticatory muscle activity, biting strength and thickness of the masticatory muscles by means of electromyography, maximal molar bite force and ultrasound imaging, respectively. The resultant data were statistically analyzed by t-tests (p<0.05). RESULTS The HIVG normalized EMG data from a mandibular rest position, protrusion, right and left laterality movement of the jaw showed that HIVG presented a relative increase in EMG activity compared to the CG. The HIVG had a lower masticatory cycle ability while chewing Parafilm M®, Raisins and Peanuts when compared to CG. During rest conditions, the ultrasound images showed a greater average muscular thickness in the right and left temporal region compared to CG. Upon maximal voluntary contraction, an increased average thickness was seen in the temporalis muscles and left sternocleidomastoid muscle when compared to the CG. CONCLUSION Based on the results of this research, it can be concluded that individuals with acquired immunodeficiency syndrome showed muscular changes related to the stomatognathic system, especially concerning EMG activity and muscle thickness.

Alterations in the stomatognathic system due to amyotrophic lateral sclerosis

Abstract Objectives: To compare the molar bite force, electromyographic activity, chewing efficiency and thickness of the masseter and temporalis muscles in individuals with amyotrophic lateral sclerosis (ALS) and healthy individuals. Material and Methods: Thirty individuals enrolled in the study were divided into the study group (with ALS, n=15) and control group (healthy individuals, n=15). Data regarding molar bite force (right and left), electromyographic activity (mandibular rest, right and left laterality, protrusion, and maximum voluntary contraction), chewing efficiency (habitual and non-habitual), and masticatory muscle thickness (rest and maximum voluntary contraction) were tabulated and subjected to statistical analysis (Student’s t-test, p≤0.05). Results: Comparisons between the groups demonstrated a statistically significant increase in the electromyographic activity of the right masseter (p=0.03) and left masseter (p=0.03) muscles during mandibular rest; left masseter (p=0.00), right temporalis (p=0.00), and left temporalis (p=0.03) muscles during protrusion; and right masseter (p=0.00), left masseter (p=0.00), and left temporalis (p=0.00) muscles during left laterality, in individuals with ALS as compared with healthy individuals. A statistically significant decrease was observed in the habitual chewing efficiency of the right masseter (p=0.00) and right temporalis (p=0.04) muscles in individuals with ALS. No statistically significant difference between the groups was found the masticatory muscle thickness and maximal molar bite force. Conclusions: ALS may lead to modifications in the activities of the stomatognathic system, including muscular hyperactivity and reduction in chewing efficiency; however, no change has been observed in the masticatory muscle thickness and molar bite force.

Evaluation of the electromyographic fatigue of the masseter and temporalis muscles in individuals with osteoporosis

Abstract Objectives The objective of this study was to evaluate the electromyographic fatigue of the masseter and temporalis muscles in individuals with and without osteoporosis. Methods Median frequency of the initial, mid, and final periods of the electromyographic signal in the 33 subjects with osteoporosis (OG) and 33 subjects without osteoporosis [control (CG)] was analyzed. Results OG showed a decrease in median frequency along the electromyographic signal, with a significant difference for the right masseter: initial vs. mid periods, initial vs. final periods; left masseter: initial vs. final periods; temporal (right and left): initial vs. mid periods, initial vs. final periods, and mid vs. final periods. Percentage comparison of median frequency between the initial and mid periods and between initial and final periods in the OG showed a significant difference in the masticatory muscles. Discussion The findings suggest that osteoporosis is associated with changes in the function of masticatory muscles, especially when measured by electromyographic fatigue.

The influence of maxillary and mandibular osteoporosis on maximal bite force and thickness of masticatory muscles

The aim of this study was to examine the bite force and masseter and temporal muscle thickness in individuals with maxillary and mandibular osteoporosis. 72 individuals were distributed into two equal groups: (1) facial osteoporosis and (2) healthy controls. Bite force on the right and left molar regions was recorded with a dynamometer and the highest value out of three measurements was recorded as the maximal bite force. Muscle thickness was measured with a SonoSite Titan ultrasound scanner. Ultrasound images were obtained of the bilateral masseter and temporal muscles at rest and at maximal voluntary contraction. The means of the measurements in each clinical condition were analyzed with multivariate statistical analysis (SPSS 19.0). Students t test indicated no significant difference for muscle thickness, but indicated significantly lower bite force values in the osteoporosis group (p>0.05). Lower bite force in individuals with facial bone loss demonstrates functional impact of osteoporosis on the complex physiological stomatognathic system.