Administration of low-level laser on muscles of mastication following the induction of initial fatigue: protocol for a randomized, controlled, clinical trial.

BACKGROUND: Orofacial pain encompasses painful conditions, such as temporomandibular disorder (TMD). Multidisciplinary health teams seek to control such musculoskeletal disorders to improve the quality and functional capacity of the muscles of mastication. The aim of the proposed study is to evaluate the effect of low-level laser therapy as a form of treatment for the prevention of initial fatigue of the muscles of mastication (masseter and anterior temporal muscles) as well as the recovery of these muscles after induced exhaustion (caused by isometric contraction) in young adults. METHODS: The participants will be 78 healthy male and female volunteers between 18 and 34 years of age. The volunteers will be randomly allocated to a laser group (n = 26), sham group (n = 26), and control group (n = 26). All participants will be submitted to a clinical evaluation to record mandibular movements, bite force, muscle sensitivity to palpation, and initial muscle fatigue. Initial fatigue will be induced by isometric contraction of the jaws. Maximum voluntary contraction will be performed to record the time until initial exhaustion of the masseter muscle (determined by electromyography). The groups will then be submitted to the interventions: active laser therapy (wavelength: 780 nm; fluence: 134 J/cm; power: 50 mW; irradiance: 1.675 W/cm; exposure time: 80 seconds per point) on 3 points of the masseter and 1 point on the anterior temporal muscles on each side; sham laser (placebo effect); or no intervention (control). Maximum voluntary contraction will be performed again after the interventions to record the time until initial exhaustion of the masseter muscle (determined by electromyography). Differences in individual time until exhaustion between the pre- and postintervention evaluations will be measured to determine the effect of low-level laser therapy. DISCUSSION: Although studies have been made with the use of low-level laser therapy in TMDs and on the effect of photobiomodulation on fatigue, this the first study to test this therapy in the prevention of fatigue in this region. The clinical relevance lies in the fact that longer dental procedures could take place if the patients are less prone to fatigue.

Prospective evaluation of relationships between radiotherapy dose to masticatory apparatus and trismus.

AIMS: This feasibility study aimed to identify relationships between radiation doses to the masticatory apparatus as a combined block or as individual subunits with changes in trismus following radiotherapy. MATERIAL AND METHODS: Twenty patients from a single center were recruited prospectively as part of a randomized trial comparing proactive exercises in the management of trismus. Patients with stage III/IV oral cavity or oropharyngeal squamous cell cancers received intensity-modulated radiotherapy with concurrent systemic therapy. All patients had trismus prior to radiotherapy. Maximal inter-incisor distance (MID) was measured pre- and 6 months from the start of radiotherapy. Bilateral muscles of mastication: medial and lateral pterygoids (MP and LP), masseters (M), temporalis (T), temporomandibular joint (TMJ) were contoured on CT images. The block comprised all muscles excluding the TMJ below the orbital floor. Mean dose, equivalent uniform dose (EUD) and V35-V60 Gy were compared with change in MID. RESULTS: In six patients, the MID deteriorated at 6 months from the start of radiotherapy compared with 14 whose MID improved. No significant association was observed between age, gender, smoking, alcohol status, exercise compliance, cisplatin, tumor site, stage, V35-V60 Gy or EUD with change in MID. A clinical outlier was excluded. Without the outlier (n = 19), a significant association was seen between mean dose and change in MID at 6 months for the ipsilateral block (p = .01), LP (p = .04) and M (p < .01). All patients where trismus deteriorated at 6 months received mean doses >40 Gy to the block. CONCLUSION: Higher mean radiation doses to the ipsilateral block, LP and M were significantly associated with deterioration in trismus. Limiting dose to these structures to ≤40 Gy for tumors not invading the masticatory muscles may improve treatment-related sequelae. The ipsilateral block, LP and M should be studied further as possible alternative avoidance structures in radiotherapy treatment planning.

Masseter and temporalis muscle electromyography findings after lower third molar extraction

Background: The main clinical application of electromyography is to detect abnormalities in muscle function, to assess muscle activity for purposes of recruitment, and in the biomechanics of movement. Objectives: To analyze electromyography (EMG) findings for masticatory muscles during chewing following surgical extraction of lower third molars, and to determine any correlation between pain, inflammation, trismus, and the EMG data registered. Material and Methods: This prospective study included 31 patients. Surface EMG was used to study masseter and temporalis muscle function before lower third molar extraction and 72 hours and seven days after surgery. Clinical variables, pain, inflammation, and trismus were registered before and after surgery. Results: Studying the area and size of the masticatory muscles, higher values were found for temporalis than masseter muscles, regardless of the surgical side, which points to the greater involvement of the temporalis muscle in mastication. Comparing the side where surgery had been performed with the non-surgical side, a sharp and statistically significant reduction in amplitude and area were noted on the surgical side reflecting major functional affectation. One week after surgery, amplitude and area had almost returned to base-line values, indicating almost complete recovery. While pain decreased progressively after surgery, inflammation peaked at 72 hours, while mouth opening reached a minimum at this time, returning to normality within the week. Conclusions: Surgical extraction of lower third molars produces changes to electromyography activity that are more evident during the first hours after surgery and closely related to the intensity of pain suffered and the patient's inflammatory responses, although they are not related to mouth opening capacity (AU)

No disponible

Importancia de la resolución de las unidades CBCT para la detección de fracturas verticales: a propósito de un caso / Importance of the resolution of the CBCT units for detection of vertical root fractures: a clinical case report

Introducción: La radiología es una herramienta esencial para hacer un diagnóstico preciso y fiable en endodoncia. La tomografía computarizada de haz cónico (CBCT) se ha introducido rápidamente en la última década en el área de diagnóstico radiológico 3D. En endodoncia se requiere el mayor nivel de calidad y resolución de imagen, pues las estructuras anatómicas implicadas son muy pequeñas. La fractura radicular vertical (FRV) en dientes con tratamiento endodóncico previo es un buen ejemplo de reto diagnóstico en el que se precisa una alta resolución del equipo de CBCT y la adquisición de imágenes con la mayor calidad posible y con la menor cantidad de artefactos y ruido. Caso clínico: Se presenta un caso en el que, una vez realizado el examen clínico y la exploración radiográfica 2D convencional, se sospecha la presencia de una FRV, prescribiéndose un estudio de CBCT, que confirma la presencia de FRV, sin separación macroscópica de sus fragmentos, e indica la extracción. Una vez extraído el diente, se realizaron dos nuevos exámenes de CBCT, con unidades de uso clínico diferentes, para su posterior comparación entre sí y con la imagen escaneada con un aparato de laboratorio de microtomografía computarizada (µCT). Discusión: Se analizan y describen los parámetros necesarios para obtención de una imagen 3D de calidad en el campo de la endodoncia Se compara la calidad de imagen proporcionada por diferentes unidades CBCT, tomando como referencia las imágenes del estudio con micro-CT. Puntos esenciales de aprendizaje: 1) No todos los equipos de CBCT poseen las características adecuadas para el diagnóstico en endodoncia. 2) La alta calidad de imagen y la resolución óptima requeridas en endodoncia sólo son proporcionadas por equipos de CBCT que adquieren imágenes con un tamaño de vóxel igual o inferior a 100 µm

Introduction: Radiology is an essential tool for making an accurate and reliable diagnosis in Endodontics. Cone-beam computed tomography (CBCT) has been introduced in the past decade in the area of 3D radiological diagnosis. Endodontics requires the higher level of image quality and resolution, because the anatomical structures involved are very small. One of the most extreme diagnostic examples is the presence of vertical root fractures (VRFs) in teeth with previous endodontic treatment. This clinical entity is an important diagnostic 3D challenge, due to the need for high resolution of the CBCT apparatus, the acquisition of images with the least amount of artifacts and noise to obtain pictures of more quality possible. This article aims to discuss and highlight the degree of image quality, resolution and required voxel size, in terms of computed tomography of cone beam, with clinical dental diagnostic purposes. Case report: A clinical case was selected, in which the presence of a VRF was suspected subsequent to the clinical examination, conventional 2D radiographic examination, and the CBCT scan. Once the tooth is extracted, two new CBCT exams were carried out with two different clinical CBCT units, for further comparison among themselves and with the scanned image using laboratory equipment for computerized micro-tomography (µCT). Discussion: The parameters needed to obtain a 3D image quality in the field of endodontics are analyzed and described. The quality of image provided by different CBCT units, taking as a reference the study with micro-CT images, is compared. Key learning points: 1) Not all CBCT units have the same characteristics and, therefore, not all are suitable for clinical diagnosis in endodontics. 2) The high image quality and excellent resolution required in endodontics are only provided by CBCT units with a voxel size ≤ 100 µm

Postradiation trismus and its impact on quality of life in patients with head and neck cancer.

OBJECTIVE: The aims of this study were to investigate the following in patients with head and neck cancer (HNC): (1) factors related to trismus that predict the development of trismus, (2) factors affecting quality of life and measurements of these factors, and (3) comparison of these findings in patients with and without trismus to evaluate the effects of trismus on quality of life. METHODS: This cross-sectional study included the questionnaires: the Hospital Anxiety and Depression Scale (HADS) - Depression Subscale, the Chewing Function Questionnaire (CFQ), and the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire - Head and Neck Cancer Module (EORTC QLQ-HN35). A scaled ruler was used to measure maximal intercisal opening (MIO). RESULTS: Of the 104 patients in the study, 8.7% had clinical depression. The average MIO was 35.81 mm, and 47.1% of patients had trismus. Moderate levels of chewing dysfunction with regard to different types of food were noted. Lower body mass index, chemoradiotherapy treatment, longer time since treatment completion, and higher radiation dose were significantly associated with trismus. Such patients had significantly lower head and neck-specific quality of life in terms of social contact, sexuality, teeth, mouth opening, dry mouth, feeling ill, nutritional supplement, and weight loss. CONCLUSIONS: Patients with trismus should be provided mouth opening exercises after treatment and programs to improve trismus and quality of life.

Evaluation of low-level laser therapy effectiveness on the pain and masticatory performance of patients with myofascial pain.

This study investigated the effect of low-level laser therapy (LLLT) on the masticatory performance (MP), pressure pain threshold (PPT), and pain intensity in patients with myofascial pain. Twenty-one subjects, with myofascial pain according to Research Diagnostic Criteria/temporomandibular dysfunction, were divided into laser group (n = 12) and placebo group (n = 9) to receive laser therapy (active or placebo) two times per week for 4 weeks. The measured variables were: (1) MP by analysis of the geometric mean diameter (GMD) of the chewed particles using Optocal test material, (2) PPT by a pressure algometer, and (3) pain intensity by the visual analog scale (VAS). Measurements of MP and PPT were obtained at three time points: baseline, at the end of treatment with low-level laser and 30 days after (follow-up). VAS was measured at the same times as above and weekly throughout the laser therapy. The Friedman test was used at a significance level of 5% for data analysis. The study was approved by the Ethics Committee of the Federal University of Sergipe (CAAE: 0025.0.107.000-10). A reduction in the GMD of crushed particles (p < 0.01) and an increase in PPT (p < 0.05) were seen only in the laser group when comparing the baseline and end-of-treatment values. Both groups showed a decrease in pain intensity at the end of treatment. LLLT promoted an improvement in MP and PPT of the masticatory muscles.

Does low intensity laser therapy reduce pain and change orofacial myofunctional conditions?

Due to its multifactorial pain aspects, combined therapies are required for the the comprehensive management of temporomandibular joint disorders (TMD). Interdisciplinary forms of therapies, such as laser therapy, and health care or medical professionals, such as speech therapists, have been proposed for this comprehensive management. The aims of this study were the following: 1. verify whether low-intensity laser therapy would promote significant pain remission; 2. evaluate whether this changes orofacial myofunctional conditions in the sample, as tested, using the Orofacial Myofunctional Evaluation with Scores (OMES); and 3. evaluate whether or not the pain improvement would remain stable after a 30-day follow-up for pain conditions. The study included 12 female volunteers diagnosed with myofascial pain and ages ranging from 18 to 60 years old, with or without intra-articular TMD, according to axis I of the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD). Participants were assessed for pain on palpation, using a visual analogue scale (VAS), before treatment (A1), immediately after 30 days of intervention, i.e, after eight sessions of Low Intensity Laser Therapy (LILT) (A2), and 30 days after the end of the treatment with LILT (A3) (follow-up). Comparing the three evaluation times, it was observed that there was a significant decrease in the values of subjective pain to palpation (p < 0.05). The initial pain (A1) differed significantly from the A2, but did not differ significantly from A3.

Dysphagia and trismus after concomitant chemo-Intensity-Modulated Radiation Therapy (chemo-IMRT) in advanced head and neck cancer; dose-effect relationships for swallowing and mastication structures.

BACKGROUND AND PURPOSE: Prospective assessment of dysphagia and trismus in chemo-IMRT head and neck cancer patients in relation to dose-parameters of structures involved in swallowing and mastication. MATERIAL AND METHODS: Assessment of 55 patients before, 10-weeks (N=49) and 1-year post-treatment (N=37). Calculation of dose-volume parameters for swallowing (inferior (IC), middle (MC), and superior constrictors (SC)), and mastication structures (e.g. masseter). Investigation of relationships between dose-parameters and endpoints for swallowing problems (videofluoroscopy-based laryngeal Penetration-Aspiration Scale (PAS), and study-specific structured questionnaire) and limited mouth-opening (measurements and questionnaire), taking into account baseline scores. RESULTS: At 10-weeks, volume of IC receiving ≥60 Gy (V60) and mean dose IC were significant predictors for PAS. One-year post-treatment, reported problems with swallowing solids were significantly related to masseter dose-parameters (mean, V20, V40 and V60) and an inverse relationship (lower dose related to a higher probability) was observed for V60 of the IC. Dose-parameters of masseter and pterygoid muscles were significant predictors of trismus at 10-weeks (mean, V20, and V40). At 1-year, dose-parameters of all mastication structures were strong predictors for subjective mouth-opening problems (mean, max, V20, V40, and V60). CONCLUSIONS: Dose-effect relationships exist for dysphagia and trismus. Therefore treatment plans should be optimized to avoid these side effects.

Radiotherapy deteriorates postoperative functional outcome after partial glossectomy with free flap reconstruction.

PURPOSE: Most patients with tongue cancer require surgical resection of the tongue to varying degrees. As a result, quality of life, which is strongly related to speech, chewing, and swallowing, can deteriorate severely from extensive surgical treatment of tongue cancer. In addition to surgery, adjuvant therapy may affect the severity of functional impairment. Therefore, the influence of postoperative radiotherapy on functional outcome after partial glossectomy with free flap reconstruction was evaluated in patients with early oral tongue cancer. PATIENTS AND METHODS: Functional outcome was measured and charts of 31 patients with oral tongue cancer who were surgically treated at Yonsei Head and Neck Cancer Clinic from 2003 through 2008 were reviewed. Only patients who underwent partial glossectomy and reconstruction with radial forearm free flap and did not develop recurrence were included. Speech integrity was evaluated with diadochokinetic testing by a professional speech therapist. Tongue mobility was checked by measurements of upward distance, protrusion distance, and lateral deviation distance. Swallowing capacity was evaluated with the M.D. Anderson Dysphagia Inventory. RESULTS: Diadochokinetic rates of the surgery-only and postoperative radiotherapy groups were 27.8 and 23.9, respectively, which was statistically different. Swallowing capacity was significantly superior in the surgery-only group. Tongue mobility was not statistically different between the 2 groups. CONCLUSIONS: Functional outcome of speech and swallowing is negatively influenced by postoperative radiotherapy.

Management of a post-radiotherapy xerostomic patient--a case report.

OBJECTIVE: The objective of the study was to fabricate complete denture with palatal reservoir filled with artificial saliva for a post radiotherapy edentulous patient. BACKGROUND: Xerostomia is a subjective complaint rather than a disease. It is caused by irradiation, medication, Sjogren's syndrome & neurological factors such as stress. Radiotherapeutic treatment of head and neck cancer patients often causes long term dysfunction involving their salivary function, swallowing capabilities & taste. All three of these domains are affected by radiation- induced damage to the salivary glands. This in turn results in poor retention of complete denture, frequent trauma to alveolar ridge & other oral infections. All these events drastically affects quality of life of ageing patients. MATERIAL AND METHOD: A complete denture in heat cure acrylic resin was fabricated in which a palatal reservoir was made on the palatal side. RESULTS: Problems arising due to xerostomia were reduced to a great extent. CONCLUSION: Prosthodontic management of Xerostomic patient include several techniques. This paper presents a case report of post radiotherapy edentulous patient in which complete denture with palatal reservoir filled with artificial saliva was fabricated.

Low intensity laser therapy in temporomandibular disorder: a phase II double-blind study.

The purpose of this study was to evaluate the analgesic effect of Low Intensity Laser Therapy (LILT) and its influence on masticatory efficiency in patients with temporomandibular dysfunction (TMD). This study was performed using a random, placebo-controlled, and double-blind research design. Fourteen patients were selected and divided into two groups (active and placebo). Infrared laser (780 nm, 70 mw, 60s, 105J/cm2) was applied precisely and continuously into five points of the temporomandibular joint (TMJ) area: lateral point (LP), superior point (SP), anterior point (AP), posterior point (PP), and posterior-inferior point (PIP) of the condylar position. This was performed twice per week, for a total of eight sessions. To ensure a double-blind study, two identical probes supplied by the manufacturer were used: one for the active laser and one for the inactive placebo laser. They were marked with different letters (A and B) by a clinician who did not perform the applications. A Visual Analogue Scale (VAS) and a colorimetric capsule method were employed. Data were obtained three times: before treatment (Ev1), shortly after the eighth session (Ev2), and 30 days after the first application (Ev3). Statistical tests revealed significant differences at one percent (1%) likelihood, which implies that superiority of the active group offered considerable TMJ pain improvement. Both groups presented similar masticatory behavior, and no statistical differences were found. With regard to the evaluation session, Ev2 presented the lowest symptoms and highest masticatory efficiency throughout therapy. Therefore, low intensity laser application is effective in reducing TMD symptoms, and has influence over masticatory efficiency [Ev2 (0.2423) and Ev3 (0.2043), observed in the interaction Evaluations x Probes for effective dosage].

Association between salivary flow rates, oral symptoms, and oral mucosal status.

OBJECTIVE: To investigate the association of salivary flow rates with oral symptoms and oral mucosal status. STUDY DESIGN: The study population included 462 Israeli subjects attending a xerostomia clinic. After patient history and oral mucosal examination, major gland sialometry, and complementary tests, patients were divided into 6 groups: drug-induced salivary gland hypofunction (SGH), Sjögren syndrome (SS), radiation-induced SGH, idiopathic SGH, xerostomia without SGH, and control. RESULTS: Oral mucosal alterations were more prevalent in all SGH groups than in the control group. Oral symptoms (except speech impairment) were more frequent in all SGH groups. The postradiation group showed the highest frequency of oral mucosal alterations and of swallowing and mastication complaints. Individuals complaining of xerostomia (compared with those who did not) displayed lower major salivary gland flow rates and a higher frequency of oral mucosal alterations CONCLUSIONS: Presence of oral mucosal alterations may help but are not enough to identify patients for further evaluation of SGH. Difficulties in mastication and swallowing are most specifically related to advanced SGH.

Effects of magnetic field exposure on open field behaviour and nociceptive responses in mice.

Results of previous studies have shown that nociceptive sensitivity in male C57 mice is enhanced by exposure to a regular 37 Hz or an irregularly varying (<1 Hz) electromagnetic field. In order to test whether these fields affect more generally mouse behaviour, we placed Swiss CD-1 mice in a novel environment (open field test) and exposed them for 2 h to these two different magnetic field conditions. Hence, we analysed how duration and time course of various behavioural patterns (i.e. exploration, rear, edge chew, self-groom, sit, walk and sleep) and nociceptive sensitivity had been affected by such exposure. Nociceptive sensitivity was significantly greater in magnetically treated mice than in controls. The overall time spent in exploratory activities was significantly shorter in both magnetically treated groups (< 1 Hz, 33% and 37 Hz, 29% of total time), than in controls (42%). Conversely, the time spent in sleeping was markedly longer in the treated groups (both 27% of total time) than in controls (11%). These results suggest that exposure to altered magnetic fields induce a more rapid habituation to a novel environment.

Effects of controllable stress on masticatory behaviour and muscle structure: partial protective effect of clomipramine.

The influence of controllable painless stress and clomipramine treatment was evaluated on masticatory behaviour and myosin heavy chain expression in masticatory rat muscles: anterior digastric, anterior temporalis and masseter superficialis. The adult fast isoforms of myosin heavy chains detected were myosin heavy chains 2A, 2X and 2B. The myosin heavy chains composition of anterior temporalis muscle was unchanged by stress or by treatment. In anterior digastric and masseter superficialis muscles, stress induced an increase in 2B and a decrease in 2X and 2A. Under stress, whereas the myosin heavy chains composition of anterior temporalis and anterior digastric muscles was unaffected by clomipramine, this drug modified significantly the myosin heavy chains composition of masseter superficialis muscle which became comparable to that of control muscle. Stress-induced myosin heavy chains transformations led to an increased velocity of anterior digastric and masseter superficialis muscles but not anterior temporalis muscle. Gnawing and mastication were increased by stress and incisor grinding was reduced. Stress shortened the duration of gnawing and increased the fatigability of anterior digastric and masseter superficialis muscles, whereas clomipramine increased the duration of mastication and reduced the fatigability of masseter superficialis muscle. Stress produces selective changes in masticatory muscles and behaviour. This study demonstrates the muscle type-specific protective effect of clomipramine against stress-induced structural transformations of masseter superficialis muscle and the specific concomitant behavioural modifications.