Characterization of Salivary Gland Pain: A Review of the Literature / Caracterización del Dolor de Glándulas Salivales: Revisión de la Literatura

SUMMARY: The salivary glands in pathological conditions produce countless different clinical presentations, and due to their complex neuroanatomy, their pain symptoms vary widely. However, in the literature to date, few studies characterize salivary gland pain. The aim of this study was to conduct a literature review concerning the clinical characteristics of pain in various salivary gland pathologies. A literature review was done through a systematic search of scientific articles in the Web of Science (WoS), MEDLINE, Scopus, and Elton B. Stephens Company (EBSCO) databases. The free terms "salivary gland", "parotid gland", "submaxillary gland", "sublingual gland", and "pain" were used along with the Boolean operators OR and AND. The search yielded a total of 1896 articles, of which 60 fulfilled the inclusion criteria and were ultimately included in this review. It is described that pain is a nonspecific symptom of a glandular pathology and is characterized mainly by the location of the pain, which is correlated with the anatomical location of the affected salivary gland. Among the painful salivary gland pathologies, we found inflammatory disorders, including infections, obstructions, disorders secondary to hyposalivation; systemic autoimmune diseases; neoplasms, and neuropathic pain disorders. The diagnosis and management of salivary gland pain require knowledge of the causes and mechanisms of the pain, and it is to recognize the signs and symptoms of salivary gland disorders to be able to diagnose and treat them.

Las glándulas salivales en condiciones patológicas producen un sinfín de presentaciones clínicas diferentes, y debido a su compleja neuroanatomía generan variaciones en su sintomatología dolorosa. Sin embargo, en la literatura hasta ahora son escasos los estudios que caracterizan el dolor de glándulas salivales. El objetivo de este estudio fue realizar una revisión de la literatura respecto a las características clínicas del dolor en diversas patologías de glándulas salivales. Se realizó una revisión de la literatura, a través de la búsqueda sistemática de artículos científicos en las bases de datos Web of Science (WoS), MEDLINE, Scopus y Elton B. Stephens Company (EBSCO). A través de los términos libres: "salivary gland", "parotid gland", "submaxillary gland", "sublingual gland", "pain", junto con los operadores booleanos OR y AND. La búsqueda arrojó un total de 1896 artículos, de los cuales 60 cumplieron los criterios de inclusión y fueron finalmente incluidos en esta revisión. Se describe que el dolor es un síntoma poco específico para la patología glandular y está caracterizado principalmente por la localización del dolor, el cual se correlaciona con la ubicación anatómica de la glándula salival afectada. Dentro de las patologías dolorosas de glándulas salivales encontramos los trastornos inflamatorios, incluidas infecciones, obstrucciones, trastornos secundarios a hiposalivación; enfermedades sistémicas autoinmunes; neoplasias y trastornos de dolor neuropático. El diagnóstico y manejo del dolor de glándulas salivales requiere del conocimiento de las causas y mecanismos del dolor, siendo necesario reconocer los signos y síntomas de los trastornos de glándulas salivales para ser capaces de diagnosticarlos y tratarlos.

Comparison of Four Treatment Protocols with Intra-Articular Medium Molecular Weight Hyaluronic Acid in Induced Temporomandibular Osteoarthritis: An Experimental Study.

The aim was to compare the effect between a single intra-articular infiltration (1i) and two infiltrations (2i) of medium molecular weight hyaluronic acid (MMW-HA) of high viscosity (HV) and low viscosity (LV) on the histopathological characteristics of temporomandibular joint (TMJ) osteoarthritis (OA) induced in rabbits. An experimental study was conducted on Oryctolagus cuniculus rabbits, including 42 TMJs, distributed between (1) TMJ-C, control group; (2) TMJ-OA, group with OA; (3) TMJ-OA-wt, group with untreated OA; (4) group treated with HA-HV-1i; (5) group treated with HA-HV-2i; (6) group treated with HA-LV-1i; and (7) group treated with HA-LV-2i. The results were evaluated using the Osteoarthritis Research Society International (OARSI) scale and descriptive histology considering the mandibular condyle (MC), the articular disc (AD), and the mandibular fossa (MF). The Kruskal-Wallis test was used for the statistical analysis, considering p < 0.05 significant. All treated groups significantly decreased the severity of OA compared to the TMJ-OA-wt group. The HA-HV-2i group showed significant differences in the degree of OA from the TMJ-OA group. The degree of OA in the HA-HV-2i group was significantly lower than in the HA-LV-1i, HA-LV-2i, and HA-HV-1i groups. The protocol that showed better results in repairing the joint was HA-HV-2i. There are histological differences depending on the protocol of the preparation used: two infiltrations seem to be better than one, and when applying two doses, high viscosity shows better results.

Differences According to the Type of Exogenous Hyaluronic Acid and its Frequency of Infiltration in the Treatment of Temporomandibular Osteoarthritis / Diferencias Según el Tipo de Ácido Hiaurónico Exógeno y su Frecuencia de Infiltración en el Tratamiento de la Osteoartritis Temporomandibular

SUMMARY: One of the most important minimally invasive treatments today in temporomandibular joint osteoarthritis (TMJ- OA) is the intra-articular exogenous hyaluronic acid (HA) injection, which has yielded good results in pain relief and improves mandibular function with few side effects. However, the effectiveness of HA continues to be controversial, partly due to the heterogeneity in the injection protocols in their molecular weight, viscosity and frequency of infiltration, among other properties. The aim of this review is to identify the differences in the histological and clinical effects of the different types of HA and the frequency of infiltration on TMJ-OA treatment. Materials and methods: A bibliographic search was performed in the PubMed, Web of Science and Scopus databases. The search was limited up to September 2022. Search terms included "osteoarthritis", "hyaluronic acid, "molecular weight", "concentration", "viscosity", "dose" and "temporomandibular", using AND/OR as Boolean terms. Results: Exogenous HA in its different molecular weights offers an improvement in histological and clinical characteristics. Apparently, low and medium molecular weight HA presents better results. No clinical studies related to the degree of HA viscosity were found. Respect to the frequency of infiltration, single injection, weekly injections for 3 weeks, weekly injections for 5 weeks and other protocols are used. However, their comparison is complex. There seems to be differences in the effects of the different HA preparations for the treatment of TMJ-OA, mainly in their molecular weight. However, the evidence remains scant.

Uno de los tratamientos mínimamente invasivos más importantes en la actualidad en la artrosis de la articulación temporomandibular (OATM) es la inyección intraarticular de ácido hialurónico (AH) exógeno, que ha dado buenos resultados en el alivio del dolor y mejora la función mandibular con pocos efectos secundarios. Sin embargo, la efectividad del AH continúa siendo controversial, en parte debido a la heterogeneidad en los protocolos de inyección en cuanto a su peso molecular, viscosidad y frecuencia de infiltración, entre otras propiedades. El objetivo de esta revisión fue identificar las diferencias en los efectos histológicos y clínicos de los diferentes tipos de HA y la frecuencia de infiltración en el tratamiento de TMJ-OA. Se realizó una búsqueda bibliográfica en las bases de datos PubMed, Web of Science y Scopus. La búsqueda se limitó hasta septiembre de 2022. Los términos de búsqueda incluyeron "osteoartritis", "ácido hialurónico", "peso molecular", "concentración", "viscosidad", "dosis" y "temporomandibular", utilizando AND/OR como términos booleanos. El HA exógeno en sus diferentes pesos moleculares ofrece una mejora en las características histológicas y clínicas. Aparentemente, el AH de bajo y medio peso molecular presenta mejores resultados. No se encontraron estudios clínicos relacionados con el grado de viscosidad del HA. Respecto a la frecuencia de infiltración, se utilizan inyecciones únicas, inyecciones semanales durante 3 semanas, inyecciones semanales durante 5 semanas y otros protocolos. Sin embargo, su comparación es compleja. Parece haber diferencias en los efectos de las diferentes preparaciones de HA para el tratamiento de la OA-TMJ, principalmente en su peso molecular. Sin embargo, la evidencia sigue siendo escasa.

Histological effect of platelet-rich plasma on temporomandibular joint osteoarthritis: systematic review in animal models

SUMMARY: The aim of this systematic review was to assess the histological effects of platelet-rich plasma (PRP) on temporomandibular joint osteoarthritis (TMJ-OA) in animal models. A systematic search was performed using PubMed, WoS, EMBASE, Science Direct and SCOPUS databases. The inclusion criteria were experimental studies in animal models that evaluated the use of PRP as a treatment for TMJ-OA with or without arthrocentesis/arthroscopy. Comparison was made to a healthy control group or to other treatment. The variables evaluated were the histological effects of the treatments, characteristics of the primary articles, characteristics of the sample studied and the risk of bias. The systematic search identified 120 studies. Eventually 5 studies were included in the analysis. Four of the studies showed a statistically significant repair in joint tissues and improvement of cartilage thickness in animals treated with PRP. The global risk of bias was unclear. The results of this systematic review suggest that PRP treatment in TMJ-OA has benefits at the histological level in cartilage, articular disc and articular bone tissue in animal models. However, due to the low number of studies and the risk of bias, further research is needed to recommend its use.

El objetivo de esta revisión sistemática fue evaluar los efectos histológicos del plasma rico en plaquetas (PRP) en la osteoartritis de la articulación temporomandibular (ATM-OA) en modelos animales. Se realizó una búsqueda sistemática en las bases de datos PubMed, WoS, EMBASE, Science Direct y SCOPUS. Los criterios de inclusión fueron estudios experimentales en modelos animales que evaluaran el uso de PRP como tratamiento para la ATM-OA con o sin artrocentesis/ artroscopia. La comparación se realizó con un grupo de control sano o con otro tratamiento. Las variables evaluadas fueron los efectos histológicos de los tratamientos, las características de los artículos primarios, las características de la muestra estudiada y el riesgo de sesgo. La búsqueda sistemática identificó 120 estudios. Finalmente se incluyeron 5 estudios en el análisis. Cuatro de los estudios mostraron una reparación estadísticamente significativa en los tejidos articulares y una mejora del grosor del cartílago en los animales tratados con PRP. El riesgo global de sesgo fue incierto. Los resultados de esta revisión sistemática sugieren que el tratamiento con PRP en la ATM-OA tiene beneficios a nivel histológico en el cartílago, el disco articular y el tejido óseo articular en modelos animales. Sin embargo, debido al escaso número de estudios y al riesgo de sesgo, se necesitan investigaciones adicionales para recomendar su uso.

Temporomandibular Joint: Review of Anatomy and Clinical Implications.

Temporomandibular joints (TMJ) are one of the most complex joints. Each one is located on one side of the face, and are composed of mandibular fossa, joint tubercle, and condylar process of mandible, separated by an articular disk. To these structures are attached ligaments and muscles, which will provide stability and movement. When TMJs work properly, jaw movements can be performed without pain or discomfort. It is important to mention that the complex formed by both TMJs will confront the maxillary with the mandibular bone and therefore will be related to the occlusion, linking these structures during growth and development.

Sleep Bruxism: An Integrated Clinical View.

The vision of adult sleep bruxism (SB) has changed over time. Thus, among the most important concomitant factors of SB noted are the pathophysiological aspect, namely sleep arousal, obstructive sleep apnea, gastroesophageal pH/gastroesophageal reflux disease, and the use or abuse of certain substances. The aim of this article was to review the main clinically relevant pathophysiological SB-associated factors and a proposal for a diagnostic process.

Effects of melanocortin-4 receptor (MC4R) antagonist on neuropathic pain hypersensitivity in rats - A systematic review and meta-analysis.

Melanocortin-4 receptor (MC4R) has been investigated as a potential drug target for the treatment of neuropathic pain. The objective of the study was to systematically identify the effects of MC4R antagonists on hypersensitivity in rat models of neuropathic pain. A systematic search was conducted using the following databases: WoS, PubMed, SCOPUS, and MEDLINE. Inclusion criteria were: rat hypersensitivity induced by models of neuropathic pain with reported effects of MC4R antagonist. Two researchers performed the selection process and data extraction. SYRCLE risk of bias tool was used. Standard mean differences (SMD) were calculated and pooled by meta-analysis using random effect models. Ten articles met the eligibility criteria and were included in the systematic review and meta-analysis. The results reveal that, in animals exposed to neuropathic pain, administration of MC4R antagonists significantly increased paw withdrawal threshold (SHU9119 SMD = 1.67, 95% CI: [0.91, 2.44], I2  = 0%; HS014 SMD = 2.2, 95% CI: [0.53, 3.87], I2  = 71%) and heat withdrawal latency (HS014 SMD = 3.35, 95% CI: [0.56, 6.14], I2  = 83%) compared to vehicle-treated animals. MC4R antagonists are effective in the alleviation of hypersensitivity in rodent neuropathic pain models. SHU9119 and HS014 antagonists showed the most prominent results. However, further investigation is needed to determine the optimal dose and time of treatment.

Effects of low and high molecular weight hyaluronic acid on the osteoarthritic temporomandibular joint in rabbit.

OBJECTIVE: To compare the effect between intra-articular infiltration of low molecular weight (LMW-HA) and high molecular weight hyaluronic acid (HMW-HA) on the histopathological characteristics of the cartilage and disc of the temporomandibular joint (TMJ) osteoarthritis (OA) induced in rabbits. MATERIAL AND METHODS: An experimental study was conducted on 38 rabbit TMJs. The effect of different hyaluronic acids was compared at 30 and 135 days. Histopathological analysis was performed. Cartilage damage was assessed with the OARSI scale. RESULTS: The severity of the induced OA according to OARSI was 3.4 degrees in the mandibular condyle (MC) and 3.2 in the mandibular fossa (MF); the articular disc (AD) presented disorganization of the collagen fibers, with randomly arranged hypertrophic chondrocytes. At 30 days, untreated TMJs worsened. TMJ treated with LMW-HA reduced its severity to 1.5 degrees in MC and 1.6 in MF, the AD presented histological aspects within normal limits. TMJ treated with HMW-HA presented 2.4 degrees in MC and 2.2 in MF, the AD maintained characteristics similar to the group with OA. At 135 days, all groups worsened. CONCLUSION: Exogenous HA is effective in the management of TMJ-OA induced in rabbits, showing cartilage and articular disc repair at 30 days. The LMW-HA group had better effects on joint tissue than HMW-HA 30 days after treatment. However, at 135 days, both groups presented regression of joint tissue repair. CLINICAL RELEVANCE: HA is effective in the anti-arthritic treatment of TMJ-OA induced in rabbits; LMW-HA shows better results in cartilage and articular disc repair than HMW-HA.

Mecanismos de modulación central del dolor: revisión de la literatura / Mechanisms of central pain modulation: literature review

RESUMEN: La percepción del dolor resulta de múltiples y dinámicos mecanismos en el sistema nervioso central (SNC) y periférico que inhiben o facilitan el estímulo y respuesta nociceptiva. Sin embargo, la principal capacidad de modulación esta a cargo del SNC. Los estímulos nociceptivos son detectados por terminaciones nerviosas libres de neuronas periféricas que sinaptan con neuronas aferentes secundarias de la médula espinal. Luego estas fibras decusan para formar las vías nociceptivas ascendentes. Una vez alcanzadas las estructuras subcorticales, se activan las neuronas del tálamo, quienes envían el estímulo hacia la corteza somatosensorial, desencadenando la percepción consciente del dolor y activando el sistema inhibitorio descendente. Para que la modulación nociceptiva se realice, es necesaria la participación de diversas sustancias o neurotransmisores que conectan áreas del SNC especializadas. Por lo tanto, el objetivo de este estudio fue realizar una revisión de la literatura respecto de los mecanismos que participan en los procesos de modulación central del dolor.

SUMMARY: Pain perception results from multiple and dynamic mechanisms in the central nervous system (CNS) and peripheral nervous system that inhibit or facilitate stimulation and nociceptive response. However, neuromodulation is mainly a function of the CNS. Nociceptive stimulus is detected by peripheral neurons receptors that synapse with the secondary afferent neurons of the spinal cord. These fibers cross to conform the ascending nociceptive pathways. Once the subcortical structures are reached, the thalamus`s neurons are activated; the thalamus send the stimulus to the somatosensory cortex, triggering the conscious perception of pain and activating the descending inhibitory system. For the nociceptive modulation to be carried out, the participation of various substances or neurotransmitters that connect specialized CNS areas is necessary. Therefore, the aim of this study was to review the literature regarding the mechanisms involved in central pain modulation processes.

Intra-articular corticosteroids for treatment of temporomandibular joint internal disorders: protocol for systematic review and network meta-analysis.

INTRODUCTION: Internal temporomandibular joint (TMJ) disorders are present in approximately 80% of patients with symptomatic temporomandibular disorders. Among the minimally invasive therapies, we find the intra-articular infiltration of substances, such as corticosteroids, hyaluronic acid or platelet-rich plasma accompanied or not by an arthrocentesis. There are several studies on minimally invasive therapy for internal TMJ disorders; however, none compares the effectiveness of the different intra-articular corticosteroids to each other.The purpose of this study is to evaluate the effectiveness of the different intra-articular corticosteroids for the treatment of internal disorders of the TMJ and compare them to each other or to other minimally invasive therapies. METHODS AND ANALYSIS: A systematic search will be carried out up to December 2019 in the electronic databases: Medline, Cochrane Library, EMBASE, SCOPUS and LILACS.Randomised clinical trials evaluating patients with internal disorders of the TMJ, with intra-articular corticosteroid therapy and comparing these to each other and/or to other minimally invasive therapy will be included. The main outcomes will be pain and range of motion measured through validated scales.Two review authors will independently screen search results, extract data from included studies and assess the risk of bias in those studies using the Revised Cochrane Risk of Bias Tool (RoB 2.0). In the case of any discrepancy and failure to reach consensus, this will be resolved by a third reviewer.A network meta-analysis will be conducted based on direct comparisons to generate indirect comparisons of the different treatments. Data will be combined in a meta-analysis using a random effects model.The principles of the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system will be used to assess the overall quality of the body of evidence associated with the main results. ETHICS AND DISSEMINATION: This protocol will not require ethical approval. The results of this review will be disseminated through peer-reviewed publications. TRIAL REGISTRATION NUMBER: CRD42019129014.

Ernest Syndrome: A Systematic Review of the Literature.

AIMS: To conduct a systematic review of the available evidence regarding the clinical characteristics and treatment of Ernest syndrome. METHODS: A systematic search was carried out in the EBSCOhost, Embase, MEDLINE, ScienceDirect, Scopus, Web of Science, and Trip databases. The free terms "stylomandibular ligament" and "Ernest syndrome" were used, and the Boolean operator "OR" was used for connection of the terms. The research protocol was registered in PROSPERO (CRD42018112914). The results of this study are presented according to the PRISMA statement, and risk of bias was assessed according to the Quality Assessment Tool for Quantitative Studies of the Effective Public Health Practice Project. RESULTS: A total of 57 articles were found, 5 of which met the selection criteria and were included in this review. The selected articles represent a population of 81 patients with primarily unilateral pain in the periauricular and mandibular areas. Diagnosis was established according to clinical history, recognition of pain on palpation of the mandibular angle, and remission following infiltration with local anesthesia. Concerning the treatments applied, infiltration with corticosteroids was highly successful, as was partial resection of the stylomandibular ligament and part of the styloid process. Furthermore, in refractory cases, the application of radiofrequency thermoneurolysis was described. CONCLUSION: The analyzed studies allow a better understanding of Ernest syndrome and the proposal of a tendinosis model for this condition. However, the evidence is scarce, and it is therefore necessary to carry out additional studies with better methodologic designs.

Mandibular condyle depth analysis in magnetic resonance of patients with temporomandibular disorders / Análisis de la profundidad del cóndilo mandibular a través resonancia magnética de pacientes con trastornos temporomandibulares

The study of the temporomandibular joint (TMJ) through imaging, is useful for the analysis of intra-articular procedures in view of its complex anatomy. Precise knowledge of the depth at which the TMJ is located is required to achieve an ideal puncture technique. The aim of this study was to measure the depth of the TMJ through magnetic resonance imaging (MRI) in patients with temporomandibular disorders (TMD). A cross-sectional study was conducted, selecting 150 MRI of patients who attended the Polyclinic for TMD and Orofacial Pain. The variables analyzed were: 1) Depth of the right and left TMJ; 2) Age of the patients; and 3) Sex of the patients. Of the total MR, 114 corresponded to women with a median age of 23 years. The median depth of the right TMJ was 17.16 mm and median on the left side was 16.98 mm, there was no statistically significant difference (p> 0.05) but there was a strong correlation (r = 0.842). There were no differences between the depths and the sex of the patients in both the right and left TMJ. There was no correlation between age and depth of TMJ. In conclusion the depth of the right and left condyle are highly correlated, being approximately 17 mm according to the population studied. There is no association between patient age and condylar depth, and there are no differences in average according to sex.

El estudio por imágenes de la articulación temporomandibular (ATM) es útil para el análisis de procedimientos intra-articulares debido a la compleja anatomía que presenta. Se requiere un conocimiento preciso de la profundidad a la cual se encuentra la ATM para una adecuada técnica de punción. El objetivo de este estudio fue medir la profundidad de laATM en relación a la piel a través de resonancia magnética (RM) en pacientes con trastornos temporomandiblaes (TTM). Se realizó un estudio transversal, seleccionando 150 RM de pacientes que asistieron al Policlínico de TTM y Dolor Orofacial. La variables analizadas fueron: 1) Profundidad de la ATM derecha e izquierda; 2) Edad de los pacientes; y 3) Sexo de los pacientes. Del total de RM, 114 correspondían a mujeres con una mediana de edad de 23 años. La mediana de la profundidad de la ATM derecha fue de 17,16 mm y la mediana del lado izquierdo fue de 16,98 mm, no hubo una diferencia estadísticamente significativa (p>0,05) pero si una fuerte correlación (r=0,842). No hubo diferencias entre las profundidades y el sexo de los pacientes tanto en la ATM derecha como en la izquierda. No hubo correlación entre la edad y la profundidad de la ATM. La profundidad de los cóndilos derecho e izquierdo están altamente correlacionados, siendo 17 mm aproximadamente en la población estudiada. No existe asociación entre la edad de los pacientes y la profundidad condilar, y no hay diferencias en promedios por sexo.

Importancia del líquido sinovial en la articulación temporomandibular y sus implicancias en la patología articular / Value of synovial fluid in the temporomandibular joint and its implications in articular pathology

RESUMEN: El objetivo de este estudio fue realizar una revisión de la literatura respecto de la importancia del líquido sinovial en la articulación temporomandibular y sus implicancias en la patología articular. El líquido sinovial corresponde a un fluido viscoso y filante de color amarillento claro, compuesto principalmente por proteínas plasmáticas, componentes celulares, moléculas lubricantes, citoquinas, factores de crecimiento y enzimas. Es producido por la membrana sinovial y se encuentra en relación directa con las superficies articulares y la membrana sinovial, mediando las interacciones entre los tejidos de las articulaciones sinoviales. En la articulación temporomandibular desempeña un papel fundamental en el mantenimiento y regulación de la fisiología, a través de funciones lubricantes, reguladoras y metabólicas, disminuyendo el roce de las superficies articulares durante todos sus movimientos. En los trastornos temporomandibulares, la composición y función del líquido sinovial se puede ver alterada por cambios en los tejido de la articulación temporomandibular, estos cambios pueden resultar en una disminución en la capacidad de lubricar las superficies articulares y generar un ambiente catabólico en el interior de la articulación, contribuyendo conjuntamente al deterioro de éstas.

SUMMARY: The aim of this study was to conduct a review of the literature on the value of synovial fluid in the temporomandibular joint and its implications in joint pathology. The synovial fluid is a viscous and filamentous fluid of a light yellow color, composed mainly of plasma proteins, cellular components, lubricating molecules, cytokines, growth factors and enzymes. It is produced by the synovial membrane and is in direct relation with the joint surfaces and the synovial membrane, mediating the interactions between the tissues of the synovial joints. In the temporomandibular joint it plays a fundamental role in the maintenance and regulation of physiology, through lubricating, regulating and metabolic functions, decreasing the friction of the joint surfaces during all its movements. In temporomandibular disorders, synovial fluid function can be altered by changes in the tissues of the temporomandibular joint, these changes can result in a decrease in the ability to lubricate the joint surfaces and generate a catabolic environment inside the joint, contributing together to the deterioration of these.

Single nucleotide polymorphisms in genes of dopaminergic pathways are associated with bruxism.

OBJECTIVES: This research aimed to evaluate the frequency of single nucleotide polymorphisms (SNPs) in dopaminergic pathway genes (DRD1, DRD2, DRD3, DRD4, DRD5, and MAOB) in patients undergoing bruxism treatment and controls. SUBJECTS AND METHODS: Patients submitted to bruxism treatment were classified in awake bruxism (61 patients), sleep bruxism (26 patients), and awake-sleep bruxism (43 patients). Control group included 59 patients. Association between circadian manifestations of bruxism and SNPs was investigated using Fisher's exact test, chi-squared test, and calculating the odds ratios and their respective 95% confidence intervals. RESULTS: The G allele of DRD2 rs1800497 SNP was associated with a significant risk reduction of awake-sleep bruxism (p = 0.041), while the C allele of DRD3 rs6280 SNP was associated with increased risk of sleep bruxism (p = 0.02), and the C allele of DRD5 rs6283 SNP was associated with decreased risk of awake bruxism (p = 0.01). CONCLUSIONS: To our knowledge, this is the first report exploring the contribution of genetic variants in dopaminergic pathways to bruxism development, considering all circadian manifestations. Our findings indicate a possible genetic influence in the etiology of awake, sleep, and awake-sleep bruxism. Therefore, further research is needed to increase the current understanding of bruxism physiopathology.

Role of hyaluronic acid in the homeostasis and therapeutics of temporomandibular joint osteoarthritis / Rol del ácido hialurónico en la homeostasis y terapéutica de la osteoartritis de articulación temporomandibular

The aim of this study was to perform a literature review regarding the role of hyaluronic acid (HA) in the homeostasis and therapeutics of temporomandibular joint (TMJ) osteoarthritis (OA). The TMJ has characteristics that give it special adaptation and recovery abilities, where HA plays a fundamental role in helping to maintain joint homeostasis, which is affected in pathological processes like OA. OA is a chronic degenerative multi-factor disease that can affect all the components of the synovial joints, causing degradation of the articular cartilage, extracellular matrix and breakage in the HA molecules. HA is a non-branched linear polysaccharide with viscosupplementation, anti-inflammatory, lubrication and pain relief effects; it also activates the intrinsic repair processes of the cartilage and normalizes the endogenous production of HA by the synoviocytes. In recent years, the therapeutic use of HA has shown evidence that supports its application in TMJ OA, improving viscosupplementation capacity, acting at the cellular and molecular levels, reducing various inflammatory mediators and improving the reparative characteristics. Its use has been studied in animal models and in humans. However, no consensus has been reached in terms of concentrations, dose, application frequency or molecular weight to be used.

El objetivo de este estudio fue realizar una revisión de la literatura respecto del rol del ácido hialurónico (AH) en la homeostasis y terapéutica de la osteoartritis (OA) de la articulación temporomandibular (ATM). La ATM presenta características que le confieren propiedades de adaptación y recuperación especiales, donde el AH juega un rol fundamental ayudando a mantener la homeostasis articular, la cual se ve afectada en procesos patológicos como la OA. La OA es una enfermedad multifactorial crónica degenerativa que puede afectar a todos los componentes de las articulaciones sinoviales, generando degradación del cartílago articular, matriz extracelular y quiebre de las moléculas de AH. El AH es un polisacárido lineal no ramificado que presenta efectos de viscosuplementación, antiinflamatorios, lubricantes, en el alivio del dolor, permite además, activar procesos intrínsecos de reparación del cartílago y normalizar la producción endógena de AH por parte de los sinoviositos. En los últimos años el uso terapéutico del AH ha presentado evidencia que sustenta su aplicación en OA de ATM mejorando la capacidad de viscosuplementación, actuando a nivel celular y molecular, disminuyendo diversos mediadores inflamatorios y mejorando las características reparativas. Su uso se ha estudiado en modelos animales y en humanos, sin embargo no existe consenso en cuanto a concentraciones, dosis, frecuencias de aplicación y peso molecular a utilizar.

Mandibular range movement in pediatric patients / Rango de movimiento mandibular en pacientes pediátricos

Assessing the normal range of manibular movement becomes an indispensable tool for the clinical evaluation of the function of the masticatory system. The aim of this study was to measure the range of mandibular movement in mouth opening, protrusion, and lateral movements in pediatric subjects from the city of Temuco, Chile and to determine their association with age, sex, and height. A cross-sectional study was performed in children aged 6-13, treated in the Teaching-Unit-Dental-Clinic at the Universidad de La Frontera, Temuco-Chile. 54 subjects participated in the study (44.4 % females); girls exhibited an average mouth opening of 51.9 mm and males of 54.8 mm. Averages were 53.5 mm for mouth opening, 11.8 mm for protrusion, 9.9 mm for right laterality, and 10.3 mm for left laterality. A statistically significant difference was found between age groups, opening, and right lateral ranges, as well as a weak to moderate correlation between mouth opening and protrusion, protrusion and right laterality, protrusion and left laterality, right and left laterality, height and mouth opening, and height and right lateral ranges. The results of this study provide specific data and evidence on the importance of evaluating all ranges of mandibular movement, relating them to each other and with variables such as age and height.

La valoración de los rangos del movimiento mandibular normal y sus respectivas variaciones constituyen una herramienta indispensable para la evaluación clínica del funcionamiento del sistema masticatorio y la búsqueda de alteraciones. El objetivo de este estudio fue medir los rangos de dinámica mandibular en movimientos de apertura bucal, protrusión y lateralidades en sujetos pediátricos de la ciudad de Temuco, Chile; y determinar su asociación con edad, sexo y estatura. Se realizó un estudio de corte transversal, en niños de 6-13 años atendidos en la Clínica Odontológica Docente Asistencial de la Universidad de La Frontera, Temuco-Chile. Se evaluaron los rangos de apertura bucal, protrusión, lateralidad derecha, lateralidad izquierda, edad, sexo y estatura de los sujetos, relacionandolos entre sí. Se evaluaron 54 sujetos (44,4 % mujeres), las niñas presentaron un promedio de apertura bucal de 51,9 mm y los niños de 54,8 mm. El promedio de apertura bucal fue de 53,5 mm; el de protrusión 11,8 mm; el de lateralidad derecha 9,9 mm; y el de lateralidad izquierda 10,3 mm. Se encontró una diferencia estadísticamente significativa entre los distintos grupos de edad y el rango de apertura y lateralidad derecha, así como también una correlación débil a moderada entre el rango de apertura bucal y el de protrusión; el de protrusión y de lateralidad derecha; el de protrusión y lateralidad izquierda; el de lateralidad derecha e izquierda; estatura y apertura bucal; estatura y lateralidad derecha. Los resultados del presente estudio cobran gran importancia, ya que además de aportar con datos específicos aporta evidencia sobre la importancia de evaluar todos los rangos de movimiento mandibular, y no solo relacionarlos entre sí, sino también con variables como la edad y estatura. De este modo se facilitará el trabajo clínico de comprender la dinámica mandibular específica de cada paciente y complementarla con la sospecha de enfermedad o el diagnóstico específico de las patologías que afectan al sistema mandibular.

Uso de ácido hialurónico en osteoartritis de articulación temporomandibular en paciente adolescente / Use of hyaluronic acid in osteoarthritis of temporomandibular joint in adolescent patient

La osteoartritis es un tipo de trastorno temporomadibular de origen articular, siendo uno de los procesos degenerativos óseos que más comúnmente afectan a la articulación temporomandibular. Se caracteriza por remodelación del hueso subcondral subyacente, deterioro y abrasión del tejido articular. Las infiltraciones intraarticulares de ácido hialurónico se consideran beneficiosas para el tratamiento del dolor y la recuperación de propiedades de los tejidos articulares. El objetivo de éste artículo es describir el uso de ácido hialurónico en el manejo de osteoartritis de articulación temporomandibular en un paciente adolescente. Paciente de sexo femenino, 15 años de edad, presenta dolor de un año de evolución en la región preauricularbilateral, con aumento de dolor en apertura máxima. Considerando el examen clínico e imagenológico se diagnostica una luxación discal con reducción con componente osteoartritico e inflamatorio bilateral. Se indica reposo mandibular, dieta líquida, AINEs y se realiza la aplicación intraarticular de ácido hialurónico(Suprahyalâ 25 mg/2,5 ml) bilateral. Se cita a control a las 2, 3 y 16 semanas donde la paciente se encuentra sin dolor espontaneo y a la palpación. El uso de ácido hialurónico es una de las alternativas terapeúticas más utilizadas para el manejo de la osteoartritis de articulación temporomandibular, sin embargo es necesario que la evidencia de su aplicación intraarticular en adolescentes y niños se consolide.

Osteoarthritis is a type of articular origin Temporomandibular disorders, being one of themost common degenerative processes affecting thetemporomandibular joint. It is characterized byremodeling of the underlying subchondral bone,deterioration and abrasion of articular tissue. Intra-articular injections of hyaluronic acid are considered beneficial for treatment of pain and recovery of joint tissues properties. The aim of this article is to describe the use of hyaluronic acid in the management of osteoarthritis of temporomandibular joint in an adolescent patient. Female patient, 15 years old,presented pain with a year of progress in the bilateral preauricular region, with increased pain at maximum aperture. Considering the clinical and imaging tests the patient was diagnosed with disk displacement with reduction with bilateral osteoarthritic and inflammatory component. Mandibular rest, liquid diet, NSAIDs were indicated and the application of intra-articular hyaluronicacid (Suprahyalâ 25 mg / 2.5 ml) bilaterally. Control was quoted at 2, 3 and 16 weeks where the patient has no spontaneous pain and tenderness. The use of hyaluronic acid is one of the most commonly usedtherapeutic alternatives for the management ofosteoarthritis of temporomandibular joint. However,further evidence of its use in intra-articular application in adolescents and children should be incorporated.

Tendinitis of the temporalis muscle: differential diagnosis and treatment: a case report / Tendinitis del músculo temporal: diagnóstico diferencial y tratamiento: informe de caso

Abstract: introduction: The temporalis muscle plays an essential role in mastication and is actively involved in the mandibular closing movement. It is covered by a fibroelastic fascia that forms its tendon. Tendinitis is a degenerative and inflammatory process, which originates in the tendon-bone junction. Signs and symptoms such as swelling, pain, tenderness on palpation, limitation of movement and mouth opening are frequently associated with other temporomandibular disorders and not with tendinitis as a causal factor. Objective: To describe a clinical case identifying the diagnostic process and management of tendinitis of the temporalis muscle. Case report: A 30-year old male patient who sought treatment after continuous squeezing pain in the zygomatic and bilateral temporal regions with increased pain during mouth opening and mandibular function. The patient referred pain in the insertion region of the tendon of the temporalis muscle. Pain was removed after using anesthesia, consequently confirming the diagnosis of tendinitis of the temporalis muscle. Primary management measures were performed and then peritendinous corticosteroids were administered. The patient did not refer spontaneous or functional pain during check-up. Conclusion: Tendinitis of the temporalis muscle is a common condition, although frequently underdiagnosed. A good differential diagnosis must be performed to avoid confusion with other common conditions such as odontogenic pain, sinusitis, arthralgia, myofascial pain and migraine. Management depends on the type of tendinitis. It usually occurs in conjunction with other types of TMD or facial pain, so it is important to know the different clinical characteristics of pathologies with similar manifestations.

Resumen: introducción: El músculo temporal es fundamental en la masticación, participa activamente en los movimientos de cierre mandibular. Está recubierto por una fascia fibroelástica que conforma su tendón. La tendinitis es un proceso degenerativo e inflamatorio, que se origina en la unión tendón-hueso. Con frecuencia, signos y síntomas como inflamación, dolor a la palpación, limitación del movimiento y apertura, son asociados a otros trastornos temporomandibulares no considerando la tendinitis como un factor causal. Objetivo: Describir un caso clínico identificando el proceso diagnóstico y el manejo de una tendinitis del músculo temporal. Descripción del caso: Paciente sexo masculino de 30 años, acude por dolor opresivo continuo en la región cigomática y temporal bilateral con aumento del dolor en apertura y función mandibular. A la palpación presenta dolor en la zona de inserción del tendón del músculo temporal, el cual se elimina al anestesiar confirmando el diagnóstico de tendinitis del músculo temporal. Se realizan medidas primarias de manejo y luego se infiltra corticoides peritendineos. Al control el paciente no presenta dolor espontáneo ni en función. Conclusión: La tendinitis del músculo temporal es una patología frecuente, aunque subdiagnosticada. Debe realizarse el correcto diagnóstico diferencial con patologías frecuentes como dolor odontogénico, sinusitis, artralgia, dolor miofascial y migraña. El manejo dependerá del tipo de tendinitis. Habitualmente se presenta en conjunto con otros o dolores faciales, por lo que es importante conocer las distintas características clínicas de patologías con presentaciones similares.

Erosión dental y sus posibles factores de riesgo en niños: revisión de la literatura / Dental erosion and possible risk factors in children: A literature review

La erosión dental corresponde a la pérdida irreversible de los tejidos superficiales del diente debido a la acción química de ácidos, donde no participan las bacterias. Se ha transformado en una afección común a nivel mundial, afectando especialmente a la población infantil por el alto consumo de bebidas ácidas y carbonatadas. Dentro de su etiología se encuentran factores de riesgo tanto intrínsecos, producidos por el propio organismo, como extrínsecos, que no tienen su origen en el mismo, pero se relacionan directamente con él. El objetivo de este artículo es realizar una revisión de la literatura sobre los posibles factores de riesgo asociados a la presencia de erosión dental en niños.

involved. It has become a common condition worldwide, especially in children, affected by the high consumption of acidic and carbonated drinks. Within its etiology there are both intrinsic risk factors, produced by the body itself, and extrinsic, whose origin is not in the body, but are directly related to it. The aim of this article is to review the literature on the potential risk factors associated with the presence of dental erosion in children.

Prevalence of vertical condilar asymmetry of the temporomandibular joint in patients with signs and symptoms of temporomandibular disorders / Prevalencia de asimetría condilar vertical de la articulación temporomandibular en pacientes con signos y síntomas de trastornos temporomandibulares

Vertical condylar asymmetry (VCA) is considered a risk factor for the development of a temporomandibular disorder (TMD). VCA is determined by comparing the vertical condylar height between the left and right condyle. Several techniques have been developed to evaluate this asymmetry, and the most common among them are developed by Kjellberg et al. (1994) and Habets et al. (1988). The objective of this study was to evaluate the similarity of the Habets' and Kjellberg's methods with regard to these results and analyze the VCA results of the temporomandibular joint in patients with signs and symptoms of TMD. We analyzed 48 patients between 12 and 65 years of age. In each patient, the percentage of condylar symmetry according to the Kjellberg's and Habets' indexes was established and related to sex, age, and signs and symptoms of TMD at admission compared with patients who are symmetrical and asymmetrical. Finally, we compared the results of two indexes. According to Habets' index, 70.8 percent of patients were classified as asymmetric, compared with Kjellberg index where it was only 54.2 percent. No statistically significant difference was found between the severity of signs and symptoms of TMD and sex, age, Habets' index, and Kjellberg's index. We also found no statistically significant difference between patient age and Kjellberg index, but between age and Habets' index, younger patients were symmetrical. We conclude that it is conceivable that the presence of VCA is not a risk factor for TMD development.

La asimetría condilar vertical (ACV) es considerada un factor de riesgo para el desarrollo de un Trastorno Temporomandibular (TTM). ACV se determina al comparar la altura condilar vertical entre el cóndilo derecho e izquierdo. Se han desarrollado diversas técnicas para evaluar esta asimetría, las más conocidas son las desarrolladas por Kjellberg et al. (1994) y Habets et al. (1988). El Objetivo de éste estudio fue evaluar la similitud de la técnica de Habets con la técnica de Kjellberg en cuanto a los resultados y analizar éstos resultados de ACV de la articulación temporomandibular en pacientes con signos y síntomas de un trastorno temporomandibular. Se analizaron 48 pacientes entre 12 y 65 años. En cada paciente se estableció el porcentaje de simetría condilar según el índice de Kjellberg y el índice de Habets y se relacionó con las variables sexo, edad, y signos y síntomas de TTM al momento del ingreso con respecto a los pacientes simétricos y asimétricos. Por último se compararon los resultados de ambos índices. Según el índice de Habets el 70,8 por ciento de los pacientes fue clasificado como asimétrico, en comparación con kjellberg donde fue solo el 54,2 por ciento. No se encontró diferencia estadísticamente significativa entre la severidad de los signos y síntomas de un trastorno temporomandibular y las variables sexo, edad, índice de Habets e índice de Kjellberg. Tampoco se encontró diferencia estadísticamente significativa entre la edad de los pacientes y el índice de Kjellberg, pero si se encontró diferencia entre la edad y el índice de Habets donde los pacientes simétricos tenían menor edad. Se concluye que es posible pensar que la presencia de ACV no representa un factor de riesgo para el desarrollo de un TTM.