Chin augmentation with the use of cannula from a single, midline entry point: Evaluation of 50 patients.

BACKGROUND: A chin that is of right size, shape, and contour plays a crucial role in overall facial balance and esthetically harmonious appearance. Dermal fillers have been widely used for correcting mild to moderate chin retrusion and resorption. AIMS: The aim of this study was to share our preferential technique for chin augmentation and to evaluate our results in 50 patients. METHODS: A total of 50 patients consisting of females who received hyaluronic acid injection for chin augmentation and rejuvenation were enrolled in the study. We have described chin augmentation technique with the use of cannula from a single, midline entry point. RESULTS: The study included 50 female patients, and the mean age was 37.56 ± 8.84 years. The median injected filler volume for augmentation of the mental area was 2.25 mL (minimum = 1, maximum = 4 mL). Four (8%) patients had ecchymosis related to the procedure. CONCLUSION: Chin has a profound effect on the perception of attractiveness and is an area of concern for rejuvenation of the lower third of the face. Our preferential technique allows the practitioners to increase the likelihood of a satisfactory esthetic outcomes and minimize the risks of the procedure.

Determining the Efficacy of the Chin-Down Maneuver Following Esophagectomy With Fiberoptic Endoscopic Evaluation of Swallowing.

OBJECTIVES: To clarify the reliability of fiberoptic endoscopic evaluation of swallowing (FEES) compared to videofluoroscopic swallowing studies (VFSSs). Second, we explored the effect of the chin-down maneuver in the presence or absence of vocal fold paralysis (VFP) using FEES in patients with 3-field lymphadenectomy (3FL) postesophagectomy. DESIGN: Retrospective data collection from FEES and VFSS. SETTING: Dysphagic clinics in the ear, nose, and throat department. PARTICIPANTS: Patients (N=15) underwent esophagectomy with 3FL at the Department of Gastroenterologic Surgery, during a period of 12 months. INTERVENTIONS: The patients underwent FEES and VFSS with neutral and chin-down maneuvers 2 weeks postoperatively. Two raters of speech pathology blindly scored aspiration, penetration, delayed initiation, and pharyngeal clearance in the pyriform sinus and vallecula, respectively, from recorded movie clips of both examinations, using the penetration aspiration scale (PAS) and modified Hyodo FEES rating scale. MAIN OUTCOME MEASURES: The intrarater and interrater correlation coefficients of each parameter examined with FEES. Statistical comparison of each parameter between FEES and VFSS and of each parameter evaluated using FEES between 2 maneuvers with or without VFP. RESULTS: The intrarater and interrater correlation coefficients of the PAS and pyriform sinus examined with FEES were both statistically consistent between the 2 raters. The PAS and pyriform sinus evaluated using FEES were significantly correlated with those evaluated in a VFSS (P<.05). The 2 parameters evaluated using FEES were significantly (P<.05) improved with the chin-down maneuver compared to the neutral maneuver, especially in VFP patients. CONCLUSION: FEES performed postesophagectomy with 3FL for evaluation of aspiration is as reliable statistically as VFSSs. The chin-down maneuver is especially useful for reducing the PAS score and pyriform sinus in VFP patients.

Evaluation of accuracy and sensory outcomes of mandibular reconstruction using computer-assisted surgical simulation.

PURPOSE: To introduce a modified protocol for mandibular reconstruction and evaluate the protocol using a standardized assessment method. METHOD: This retrospective study involved a case series of nine patients who underwent mandibular reconstruction between 2015 and 2017. The modular protocol comprised three novel modifications in terms of computer-assisted surgical simulation (CASS); surgical template (ST), and surgical procedure. The standardized postoperative evaluation consisted of operation time, part comparison analysis (PCA), facial symmetry, and mechanical quantitative sensory testing. RESULTS: The surgery successfully removed the affected mandible and preserved the inferior alveolar neurovascular bundle (IANB). PCA revealed that the mean error and standard deviation were 0.92 and 0.96 mm, respectively, for all mandibular surface sites. Follow-up results showed good facial symmetry, existence of sensation in lower lip, and no significant differences in pulp vitality between both sides (p = 0.181). Also, the results showed a reduction in the overall operating time. CONCLUSION: The modified mandibular reconstruction method used in this study could repair lateral mandibular defects and preserve the sensory function of the chin and lower lip.

Perception of aesthetics and personality traits in orthognathic surgery patients: A comparison of still and moving images.

It is common in practicing orthognathic surgery to evaluate faces with retruded or protruded chins (dysgnathic faces) using photographs. Because motion may alter how the face is perceived, we investigated the perception of faces presented via photographs and videos. Two hundred naïve raters (lay persons, without maxillo facial surgery background) evaluated 12 subjects with varying chin anatomy [so-called skeletal Class I (normal chin), Class II (retruded chin), and Class III (protruded chin)]. Starting from eight traits, with Factor analysis we found a two-Factor solution, i.e. an "aesthetics associated traits cluster" and a Factor "personality traits cluster" which appeared to be uncorrelated. Internal consistency of the Factors found for photographs and videos was excellent. Generally, female raters delivered better ratings than males, but the effect sizes were small. We analyzed differences and the respective effect magnitude between photograph and video perception. For each skeletal class the aesthetics associated dimensions were rated similarly between photographs and video clips. In contrast, specific personality traits were rated differently. Differences in the class-specific personality traits seen on photographs were "smoothed" in the assessment of videos, which implies that photos enhance stereotypes commonly attributed to a retruded or protruded chin.

Intraoral Observation of the Mentalis and Incisivus Labii Inferioris Muscles.

The mentalis (MT) and the incisivus labii inferioris (ILI), which are accessory muscles of the orbicularis oris (OO) muscle, form an intertwined and three-dimensionally related complex. The purpose of this study is to clarify the relationship between the MT, ILI, and OO muscles via intraoral dissection. Twenty-two sides from 11 fresh adult Caucasian cadaveric heads were used, and the MT, ILI, and OO dissected under the surgical microscope. Next, measurements of the bony attachment were carried out on another 12 sides. The fibers of the MT were separated into 2 parts: a superior and an inferior part with the former coursing anteromedially and joining the inferior part of the OO. The latter coursed anteroinferiorly to the skin of the chin. The ILI traveled anterolaterally and joined the inferior part of the OO. Inferior labial branches of the mental nerves ran on the OO. There was a significant difference (P = 0.0001) between specimens that were edentulous or had severe periodontitis with regard to the distance from the alveolar ridge to the upper side of the quadrangle when compared with specimens with mild periodontitis. However, there was no significant difference (P > 0.05) between specimens that were edentulous or had severe periodontitis specimens with mild periodontitis with regard to the distance from the inferior border of the mandible to the lower side of the quadrangle. We believe that the observations of this study could help surgeons better understand the anatomy of the chin and minimize complications following surgical and other invasive procedures in this area.

Effects of Chin-Down Maneuver on the Parameters of Swallowing Function After Esophagectomy With 3-Field Lymphadenectomy Examined by Videofluoroscopy.

OBJECTIVES: To determine the effect of the chin-down maneuver after esophagectomy with 3-field lymphadenectomy (3FL) on pharyngeal residue, upper esophageal sphincter (UES) opening, and laryngeal closure. DESIGN: Prospective data were collected from a pharyngeal videofluoroscopic swallowing study. SETTING: Dysphagia clinics. PARTICIPANTS: Patients selected according to the inclusion criteria (N=14; mean age, 65.9y) from a total of 43 patients who underwent esophagectomy with 3FL from May to December 2014 were enrolled. INTERVENTIONS: Videofluoroscopy was conducted in head-neutral and chin-down positions to measure the pharyngeal constriction ratio (PCR), amount of residue in the vallecula and pyriform sinus after the first swallow, UES opening diameter, duration of UES opening, and duration of laryngeal vestibule closure. MAIN OUTCOME MEASURES: The aforementioned parameters were compared statistically between the head-neutral and chin-down positions. RESULTS: In comparison with the neutral group, the PCR and residue in the pyriform sinus were significantly smaller in the chin-down group (P<.01). However, the residue in the vallecula did not differ significantly from that of the neutral group (P=.44). The UES opening diameter, duration of UES opening, and duration of laryngeal vestibule closure were all significantly larger in the chin-down group than in the neutral group (P<.05). CONCLUSIONS: This study demonstrates that use of the chin-down maneuver after esophagectomy with 3FL can help expedite swallowing by strengthening pharyngeal constriction, widening the UES, and enhancing laryngeal closure.

Treating Scars of the Chin and Perioral Region.

Lip and chin scarring occurs owing to reconstruction of congenital, cancer resection, or traumatic defects. Knowledge of lip anatomy and function is critical to optimize results. Realistic expectations should be established before intervention. Scar revision and reconstruction is ideally performed with a subunit approach, placing scars along aesthetic borders and performing subunit reconstruction to camouflage scars. Surgical techniques include direct excision, scar reorientation, local flap rearrangement, pedicled flaps, and regional or free flaps. Resurfacing/adjunctive procedures play important roles in the treatment of scars. This article reviews the anatomy, patient assessment, and techniques used in scar revision of the perioral region.

Optimal chin-brow vertical angle for sagittal visual fields in ankylosing spondylitis kyphosis.

PURPOSE: Chin-brow vertical angle (CBVA) is very important in correction of thoracolumbar kyphotic deformity in ankylosing spondylitis (AS), especially for the patients with cervical ankylosis. In previous study, Suk et al. stated that the patients with CBVA between -10° and 10° had better horizontal gaze. Unfortunately, in our clinical practice, we found the patients with CBVA between -10° and 10° after surgery usually complained of difficulty in cooking, cleaning, desk working and the like, although they had excellent horizontal gaze. In other words, for the patients with cervical ankylosis, good horizontal gaze existed together with poor downward gaze. Then, which condition do the patients prefer? Is there a compromise solution that makes a better quality life possible for the patients? In this research, we studied AS patients with cervical ankylosis, aiming to investigate the optimal CBVA for deformity correction. METHODS: 25 AS thoracolumbar kyphotic patients with cervical ankylosis were studied, whose function and expectation of visual field related to life quality were assessed by questionnaire before and after surgery. Pre- and post-operative CBVA were obtained on lateral photos of the patients with free-standing posture, and 50 cases of CBVA were included, which were divided into six groups according to the angle irrespective of surgery (Group A, CBVA <0°; Group B, 0° ≤ CBVA < 10°; Group C, 10° ≤ CBVA < 20°; Group D, 20° ≤ CBVA < 30°; Group E, 30° ≤ CBVA < 40°; Group F, CBVA ≥ 40°). Kruskal-Wallis test was used to assess all the groups in terms of various items in the questionnaire, while Mann-Whitney test was used to assess every two groups. RESULTS: In overall evaluation, Group C (10°-20°) obtained the optimal expectation (p < 0.05); Group B, C and D (0°-30°) obtained better function (p < 0.05), and there was no significant difference between the 3 groups. In appearance, Group A, B and C (<20°) were better than the other groups both in function and expectation (p < 0.05), without dramatic difference among the three groups. In outdoor activities, Group A, B, C and D (<30°) were better in most of the items (p < 0.05). In indoor activities, Group C and D (10-30°) were much better (p < 0.05). CONCLUSION: AS thoracolumbar kyphotic patients with cervical ankylosis had the best satisfaction when 10° ≤ CBVA < 20°.

The effectiveness of the head-turn-plus-chin-down maneuver for eliminating vallecular residue

ABSTRACT Purpose When swallowing efficiency is impaired, residue accumulates in the pharynx. Cued or spontaneous swallows in the head neutral position do not always successfully clear residue. We investigated the impact of a novel maneuver on residue clearance by combining a head turn with the chin down posture. Methods Data were collected from 26 participants who demonstrated persistent vallecular residue after an initial head neutral clearance swallow in videofluoroscopy. Participants were cued to perform a head-turn-plus-chin-down swallow, with the direction of head turn randomized. Pixel-based measures of residue in the vallecular space before and after the maneuver were made on still frame lateral images using ImageJ software. Measures of % full and the Normalized Residue Ratio Scale (NRRS) were extracted. Univariate analyses of variance were used to detect significant reductions in residue. Results On average, pre-maneuver measures showed residue filling 56-73% of the valleculae, depending on stimulus consistency (NRRS scores: 0.2-0.4). More than 80% of pre-swallow measures displayed NRRS ratios > 0.06, a threshold previously linked to increased risk of post-swallow aspiration. Conclusion The head-turn-plus-chin-down maneuver achieved significant reductions in residue for thin and nectar-thick fluids, suggesting that this maneuver can be effective in reducing persistent vallecular residue with these consistencies.

Differences in the structure and osteogenesis capacity of the periosteum from different parts of minipig mandibles.

PURPOSE: To compare the structural and cellular differences of the periosteum from different parts of the mandible in minipigs by use of histologic and immunohistochemical methods to confirm the areas in which periosteal osteogenesis in situ can be used to treat mandible defects. MATERIALS AND METHODS: Three minipigs were killed, and the left mandible of each was retrieved with the periosteum remaining and then fixed, decalcified, and embedded. The specimens were cut from the buccal and lingual sides of the ramus, angle, and body of the mandible and the mentum. Sections were stained with hematoxylin-eosin and antibodies for Stro-1 (stem cell marker) and vWF (endothelial cell marker). For each periosteal area, the thickness and number of positive cells for each antibody were measured and analyzed. RESULTS: The mentum and mandibular angle periostea were thicker than those of the body and ramus. In addition, there were more blood vessels in the periostea of the mentum and mandibular body than the angle and ramus. There were more Stro-1-positive cells in the ramus periosteum than the mentum, body, and angle of the mandibles. CONCLUSIONS: The structure and cell populations of the periosteum appear to be site specific. Therefore we suggest periosteal osteogenesis in situ to treat mentum and mandibular body defects. The periosteum should be preserved as much as possible to guarantee a good healing process.

Psychometric functions for efficient and effective psychophysical testing of sensory function.

An efficient test for sensory function has been reported using random order pairs of real and sham stimuli. The constant magnitude of the real stimulus is chosen such that the first error in a patient's forced-choice report on the order of real and sham stimulation, immediately indicates abnormal sensory function. This magnitude just exceeds a critical large percentile of the psychometric function (i.e. the relationship between percentage of detection and stimulus magnitude in healthy subjects). The aim was to determine psychometric functions for one tongue site and six facial sites for adjusting three variants of the real/sham stimulus method (i.e. for light touch, cold sensation and for two-point discrimination). All 150 healthy subjects participated in testing for light touch sensation, 100 subjects additionally participated in testing two-point discrimination and 50 subjects participated additionally in testing cold sensation. The stimulus magnitude was varied using a staircase-limits procedure. Following curve fitting with a Boltzmann function, 90th, 95th or 99th percentiles of the psychometric functions were determined. A set of at least two real/sham tests, one testing the function of large nerve fibres and one for small fibres, allows quick assessment of a patient's disturbed sensory function including its fibre pathology.

The effect of age and sex on facial mimicry: a three-dimensional study in healthy adults.

To assess sex- and age-related characteristics in standardized facial movements, 40 healthy adults (20 men, 20 women; aged 20-50 years) performed seven standardized facial movements (maximum smile; free smile; "surprise" with closed mouth; "surprise" with open mouth; eye closure; right- and left-side eye closures). The three-dimensional coordinates of 21 soft tissue facial landmarks were recorded by a motion analyser, their movements computed, and asymmetry indices calculated. Within each movement, total facial mobility was independent from sex and age (analysis of variance, p>0.05). Asymmetry indices of the eyes and mouth were similar in both sexes (p>0.05). Age significantly influenced eye and mouth asymmetries of the right-side eye closure, and eye asymmetry of the surprise movement. On average, the asymmetry indices of the symmetric movements were always lower than 8%, and most did not deviate from the expected value of 0 (Student's t). Larger asymmetries were found for the asymmetric eye closures (eyes, up to 50%, p<0.05; mouth, up to 30%, p<0.05 only in the 20-30-year-old subjects). In conclusion, sex and age had a limited influence on total facial motion and asymmetry in normal adult men and women.

Accuracy and reliability of thermal threshold measurement in the chin using heat flux technique.

BACKGROUND: Neurosensory disturbance (NSD) occasionally develops in the chin following dental treatments, and evaluation of the involved nerve damage is important for treatment. The thermal-threshold test is a method of evaluating nerve sensations, but it is not widely used because its accuracy and reliability have not yet been determined. PURPOSE: This study aimed to determine the accuracy and reliability of thermal-threshold measurement of the chin by using the heat-flux technique. MATERIALS AND METHODS: The subjects were 19 healthy volunteers (7 women, 12 men), aged 21 to 36 years (mean age +/- SD, 27.2 +/- 4.5 years). The thermal thresholds, including the warm and cold heat-flux thresholds (WHF and CHF, respectively) were measured on the chin, forehead, and neck by using a thermostimulator. To evaluate test-retest reliability, we measured the thermal thresholds on 3 different days (days 1, 3, and 7). RESULTS: The WHF and CHF of the right chin were 460 +/- 165 W/m(2) (mean +/- SD W/m(2)) and 589 +/- 133 W/m(2), respectively, and those of the left chin were 446 +/- 112 W/m(2) and 576 +/- 147 W/m(2), respectively. The thermal thresholds of the right and left chin were significantly correlated (R = 0.89, P < .001). Thermal-threshold measurement was more accurate in the case of the chin than in the case of the neck. The thermal thresholds measured over the 3 days varied very little (intraclass correlation coefficient, 0.80-0.81), indicating high test-retest reliability. CONCLUSION: The heat-flux technique is accurate and highly reliable. Therefore, it may be a useful method for determining the thermal threshold of the chin.

Effect of forebrain implants of testosterone or estradiol on scent-marking and sexual behavior in male and female rabbits.

Chinning consists of rubbing the chin against an object, thereby depositing secretions from the submandibular glands. As mating, chinning is stimulated in male and female rabbits by testosterone and estradiol, respectively. To investigate the brain sites where steroids act to stimulate chinning and mating we implanted into the ventromedial hypothalamus (VMH) or the medial preoptic area (MPOA) of gonadectomized male and female rabbits testosterone propionate (TP; males) or estradiol benzoate (EB; females) and quantified chinning and sexual behavior. EB implants into the VMH or MPOA reliably stimulated chinning in females. Most of those implanted into the VMH and around half of the ones receiving EB into MPOA or diagonal band of Broca (DBB) showed lordosis. Chinning, but not sexual behavior, was stimulated in males by TP implants into the MPOA or DBB. Neither chinning nor mounting were reliably displayed by males following TP implants into the VMH. Results indicate that, in females, the VMH is an estrogen-sensitive brain area that stimulates both chinning and lordosis while the MPOA seems to contain subpopulations of neurons involved in either behavior. In males, androgen-sensitive neurons of the MPOA, but not the VMH, are involved in chinning stimulation but it is unclear if these areas also participate in the regulation of copulatory behavior.

Sensitivity of the inferior lip and chin following mandibular bilateral sagittal split osteotomy using Piezosurgery.

BACKGROUND: Bimaxillary osteotomy, including bilateral sagittal split osteotomy, is the most commonly performed orthognathic surgical intervention in Europe and the United States. Neurosensory perturbation in the territory of the inferior alveolar nerve is a reported adverse effect of bilateral sagittal split osteotomy. Piezosurgery is a relatively new technique that allows bone to be cut while preserving soft tissues, including nerves. The purpose of this study was to assess inferior alveolar nerve function through clinical neurosensory testing after bilateral sagittal split osteotomy using Piezosurgery. METHODS: Between February and September of 2004, 20 patients (40 sides) presenting with dentoskeletal deformities underwent bimaxillary osteotomy, including bilateral sagittal split osteotomy. The Mectron Piezosurgery device was used to perform all sagittal splits, with distraction being performed between the two bone valves. The inferior alveolar nerve was evaluated both objectively with clinical neurosensory testing, including pin-prick sensation, light touch sensation, and two-point discrimination tests, and subjectively at the following time points: preoperatively; at days 5, 7, and 10, postoperatively; and at the second month postoperatively. RESULTS: The anatomical integrity of the inferior alveolar nerve was respected in all cases. Observed normal results for the different tests at 10 days were 90, 82, and 70 percent, respectively, for pin-prick sensation, light touch sensation, and two-point discrimination. By computing scores for different clinical neurosensory tests, the authors observed between 75 and 80 percent complete neurosensory recuperation as early as the second postoperative month. CONCLUSIONS: Piezosurgery used for bilateral sagittal split osteotomy allows prompt recovery of inferior alveolar nerve neurosensory function within 2 months. No comparison is possible with the results using the standard technique for bilateral sagittal split osteotomy.

Superposiciones / Superimpositions

En este trabajo se describen 5 áreas de superposición y 7 áreas de evaluación entre la telerradiografía inicial y el VTO. El objetivo de las superposiciones es poder evaluar los cambios que se producen por crecimiento y los que son factibles realizar por tratamiento. Cabe destacar que las ciencias biológicas no son exactas, por lo tanto todas estas herramientas sirven para aproximarnos al ideal y son de gran utilidad si se tiene en cuenta sus múltiples variables, si por el contrario se las propone como un método exacto llevarán al fracaso

The effects of common airway maneuvers on airway pressure and flow in children undergoing adenoidectomies.

UNLABELLED: Obstruction of the upper airway occurs frequently in anesthetized, spontaneously breathing children, especially in those with adenoidal hyperplasia. To improve airway patency, maneuvers such as chin lift (CL), jaw thrust (JT), and continuous positive airway pressure (CPAP) are often used. In this study, we examined the comparative efficacy of these maneuvers in children scheduled to undergo adenoidectomy. Sixteen children aged 2-9 yr were anesthetized with sevoflurane. During spontaneous breathing, the flows and pressures in the mask (ma), oropharynx (op), and esophagus (es) were measured simultaneously, and maximal pressure differences during inspiration (DeltaP) were calculated. After baseline recording, CL and JT maneuvers were performed in random order without and with CPAP (5 cm H(2)O). The observed DeltaP(ma) - P(es) of 12.3 +/- 3.4 cm H(2)O at baseline decreased with all airway maneuvers (P < 0.05). This resulted from decreases of DeltaP(ma) - P(op) (P < 0.05) and DeltaP(op) - P(es) (P < 0.05) in all interventions except CL, in which DeltaP(ma) - P(op) remained similar. In contrast, significant improvements of minute ventilation and maximal inspiratory peak flow (P > 0.05) were observed only with JT (with and without CPAP). We conclude that CL may improve airway patency and ventilation, whereas JT with or without CPAP was the most effective maneuver to overcome airway obstruction in children with adenoidal hyperplasia. IMPLICATIONS: Airway maneuvers are often used in anesthetized children to relieve airway obstruction during spontaneous ventilation. Compared with chin lift and continuous positive airway pressure, the jaw thrust maneuver was the most effective to improve airway patency and ventilation in children undergoing adenoidectomy.

Rigid versus wire fixation for mandibular advancement: skeletal and dental changes after 5 years.

The bilateral sagittal split osteotomy (BSSO) is the most common surgical procedure for the correction of mandibular retrognathism. Commonly, the proximal and distal segments are fixated together with either wire or rigid screws or plates. The purpose of this study was to compare long-term (5 years) skeletal and dental changes between wire and rigid fixation after BSSO. In this multisite, prospective, randomized clinical trial, the rigid fixation group received three 2-mm bicortical position screws, and the wire fixation group received inferior border wires and 6 weeks of skeletal maxillomandibular fixation with 24-gauge wires. Cephalometric films were obtained 2 weeks before surgery and at 1 week, 8 weeks, 6 months, 1 year, 2 years, and 5 years after surgery. Linear cephalometric changes were referenced to a cranial base coordinate system. Before surgery, both groups were comparable with respect to linear and angular measurements of craniofacial morphology. Both groups underwent similar surgical changes. Skeletal and dental movements occurred in both groups throughout the study period. Five years after surgery, the wire group had 2.2 mm (42%) of sagittal skeletal relapse, while the rigid group remained unchanged from immediately postsurgery. Surprisingly, at 5 years, both groups had similar changes in overbite and overjet. This was attributed to dental changes in the maxillary and mandibular incisors. Although rigid fixation is more stable than wire fixation for maintaining the skeletal advancement after a BSSO, the incisor changes made the resultant occlusions of the 2 groups indistinguishable.

Evaluation of the slot osteosynthesis technique in mandibular advancement. With focus on occlusion and lower lip sensibility.

The slot osteosynthesis technique (SLOT) was evaluated in 25 mandibular advancements. SLOT was successfully used to readjust skeletal and occlusal malpositioning in 48% of the cases. Neurosensory tests in the lower lip and chin region revealed a low disturbance rate (immediately postsurgery 20% of patients, at 7 months 8%). This may be due to the specific splitting and fixation techniques applied.

Estudo do período de silêncio eletromiográfico nos distúrbios funcionais do sistema estomatognático / Study of the electromyographic silent period in the functional disorders of the stomatognathic system

O período de silêncio observado no eletromiograma dos músculos elevadores da mandíbula é resultante de uma inibiçäo reflexa do núcleo motor do nervo trigêmio induzida por estímulos provenientes dos fusos musculares e dos mecamorreceptores do periodonto. A partir da observaçäo de que a sua duraçäo estava aumentada nos registros eletromiográficos obtidos de pacientes com disfunçäo da ATM, o uso dessa medida passou a ser indicado como método objetivo de diagnóstico dessa disfunçäo. Entretanto, assim como alguns investigadores observaram na disfunçäo da ATM aumento significante na duraçäo do PS, outros colocaram dúvidas a respeito do uso por näo encontrarem esse aumento ou por näo o observarem em todos os pacientes com disfunçäo. Por outro lado, näo existem na literatura dados consistentes a respeito da duraçäo do PS eletromiográfico em outros tipos de disfunçöes oclusais e também näo foram encontrados relatos a respeito da duraçäo do PS eletromiográfico em pacientes portadores de fissura de lábio e de palato que apresentam grandes disfunçöes oclusais...