Wnt signalling in oral and maxillofacial diseases.

Wnts include more than 19 types of secreted glycoproteins that are involved in a wide range of pathological processes in oral and maxillofacial diseases. The transmission of Wnt signalling from the extracellular matrix into the nucleus includes canonical pathways and noncanonical pathways, which play an important role in tooth development, alveolar bone regeneration, and related diseases. In recent years, with the in-depth study of Wnt signalling in oral and maxillofacial-related diseases, many new conclusions and perspectives have been reached, and there are also some controversies. This article aims to summarise the roles of Wnt signalling in various oral diseases, including periodontitis, dental pulp disease, jaw disease, cleft palate, and abnormal tooth development, to provide researchers with a better and more comprehensive understanding of Wnts in oral and maxillofacial diseases.

Anatomical changes within the medullary dorsal horn in chronic temporomandibular disorder pain.

Accumulated evidence from experimental animal models suggests that neuroplastic changes at the dorsal horn are critical for the maintenance of various chronic musculoskeletal pain conditions. However, to date, no study has specifically investigated whether neuroplastic changes also occur at this level in humans. Using brain imaging techniques, we sought to determine whether anatomical changes were present in the medullary dorsal horn (spinal trigeminal nucleus caudalis) in subjects with the chronic musculoskeletal pain. In twenty-two subjects with painful temporomandibular disorders (TMDs) and forty pain-free controls voxel based morphometry of T1-weighted anatomical images and diffusion tensor images were used to assess regional grey matter volume and microstructural changes within the brainstem and, in addition, the integrity of ascending pain pathways. Voxel based morphometry revealed significant regional grey matter volume decreases in the medullary dorsal horn, in conjunction with alterations in diffusivity properties, namely an increase in mean diffusivity, in TMD subjects. Volumetric and mean diffusivity changes also occurred in TMD subjects in regions of the descending pain modulation system, including the midbrain periaqueductal grey matter and nucleus raphe magnus. Finally, tractography revealed altered diffusivity properties, namely decreased fractional anisotropy, in the root entry zone of the trigeminal nerve, the spinal trigeminal tract and the ventral trigeminothalamic tracts of TMD subjects. These data reveal that chronic musculoskeletal pain in humans is associated with discrete alterations in the anatomy of the medullary dorsal horn, as well as its afferent and efferent projections. These neural changes may be critical for the maintenance of pathological pain.

An osteochondroma of the mandibular condyle.

OBJECTIVE: Osteochondroma is rarely seen in the facial region, especially around the condyle. Here, we report a case of condylar osteochondroma, aiming to assist the diagnosis and treatment of the tumor. METHODS: A case of osteochondroma of the left mandibular condyle in a 49-year-old man was presented. Medical records with x-ray, computed tomographic scan, and bone scan of histologically proven osteochondroma of mandibular condyle were obtained. RESULTS: The patient underwent a surgical resection and had fewer functional changes as well as less dysfunction of the temporomandibular joint. CONCLUSIONS: The current study highlights the fact that, despite its rarity in the mandibular condyle, surgical resection is an effective treatment method. The decision, however, depends on how much swing of the mandible is required after surgery for correction of asymmetry and occlusion.

Surgical treatment of temporomandibular disorder in a 24-year-old male patient with ganglion cyst.

Ganglion cysts are common pseudocystic masses, whereas those arising from the temporomandibular joint (TMJ) are rare entities. We report a case of ganglion cyst of the right TMJ with symptomatic bilateral TMJ internal derangement in a 24-year-old man. Disk repositioning using bone anchors and excision of the ganglion cyst were performed. A unique characteristic of inflammatory infiltrates was revealed in the specimen, and the relationship between these 2 distinct entities and probable pathogenesis of infectious involvement are discussed.

[Features of the hormonal status in patients with temporomandibular joint dysfunction and class II malocclusion].

The article presents data on androgen levels in female patients with temporomandibular joint (TMJ) dysfunction of varying degree and class II malocclusion. The study revealed significant correlation between degenerative and inflammatory TMJ changes and androgens level in patients with stigmas of connective tissue dysplasia (p<0.05), probably due to indirect proinflammatory action of androgens as they stimulate inflammatory mediators expression.

[The peculiarities of petrotympanic fissure topography in Costen syndrome and possible causes of its development].

A complex study of morphometric characteristics of the articular surfaces of the temporomandibular joint and the examination of the peculiarities of the petrotympanic fissure topography were performed on 138 samples of skulls of adult individuals with intact occlusion, complete anodontia and different forms of cranial skull (dolicho-, meso- and brachicranial). No distinct differences in studied parameters were found between the studied groups. However, in the hypsicranial group the petrotympanic fissure was found to pass more often through the medial third of the mandibular fossa, which may be a predisposing anatomical factor for Costen syndrome. Due to the fact that in anodontia the parameters characterizing the articular surfaces of the temporomandibular joint, are significantly changed, the immediate cause of the Costen syndrome are the changes of the articular surfaces of the temporomandibular joint, primarily the reduction in the size of mandibular condyle, which is accompanied by its pathological displacement and compression of the chorda tympani.

Disc and condylar head position in the temporomandibular joint with and without disc displacement.

The purpose of this study was to evaluate the difference between disc and condyle position between temporomandibular joints (TMJs) without disc displacement (DD) in asymptomatic volunteers, and patients who have DD in contralateral joints, respectively unilateral DD. Secondly, there were two TMJ groups which consisted of measurements from patients' symptomatic DD and volunteers with asymptomatic DD. The study included 79 TMJs of 40 patients with unilateral DD. In the group of 25 asymptomatic volunteers, 20 volunteers were without DD bilaterally (40 joints), while five had DD in at least one TMJ. All subjects were examined clinically and DD was confirmed by magnetic resonance imaging. Left and right TMJs were analysed independently for each participant based on their DD status (symptomatic, asymptomatic, and without DD). All asymptomatic TMJs did not have any clinical signs of TMJ functional abnormalities. There was a significant statistical difference between disc position among TMJs without DD in asymptomatic volunteers and TMJs without DD in patients (p = 0.016). Moreover, no significant differences were found between condyle position in the same groups of joints (p = 0.706). There were no significant differences in the DD position (p = 0.918) or condyle position (p = 0.453) between the group with asymptomatic volunteers' joints and the group with symptomatic patients' joints. There was a significant difference between patient and volunteers' joints without DD: the disc was positioned more anteriorly in patients' joints without DD than in joints of asymptomatic volunteers without DD.

Total antioxidant capacity and total oxidant status of synovial fluids in patients with temporomandibular joint pain and dysfunction.

OBJECTIVES: The objective of this study was to investigate whether a relationship exists between total antioxidant capacity (TAC) and total oxidant status (TOS) of synovial fluids (SFs) of temporomandibular joint (TMJ) pain patients with pain and dysfunction. MATERIALS AND METHODS: Forty-two patients with TMJ pain were included in this study. TAC and TOS values of SFs were measured with a novel colorimetric method. Independent t test and correlations were used to analyze the data. RESULTS: TAC of SFs in patients with TMJ pain and limited mouth opening (LMO; n = 21) were significantly lower (P = 0.03) than patients without LMO (n = 21). TOS of SF was negatively correlated with duration of the disease. There was no correlation between TAC, TOS, and VAS scores of the patients as well as age and maximum mouth opening values. CONCLUSIONS: Antioxidant response to oxidative changes (TAC and TOS) in SF decreased as the stage of dysfunction increased. CLINICAL RELEVANCE: Local administration of antioxidant agents might be considered in management of TMJ pain and dysfunction to prevent possible increased oxidative stress.

Changes in regional gray and white matter volume in patients with myofascial-type temporomandibular disorders: a voxel-based morphometry study.

AIMS: To use magnetic resonance imaging (MRI) and voxel-based morphometry (VBM) to search for evidence of altered brain morphology in patients with temporomandibular disorders (TMD). METHODS: Using VBM, regional gray and white matter volume was investigated in nine TMD patients and nine carefully matched healthy controls. RESULTS: A decrease in gray matter volume occurred in the left anterior cingulate gyrus, in the right posterior cingulate gyrus, the right anterior insular cortex, left inferior frontal gyrus, as well as the superior temporal gyrus bilaterally in the TMD patients. Also, white matter analyses revealed decreases in regional white matter volume in the medial prefrontal cortex bilaterally in TMD patients. CONCLUSION: These data support previous findings by showing that TMD, like other chronic pain states, is associated with changes in brain morphology in brain regions known to be part of the central pain system.

The influence of cervical spine rehabilitation on bioelectrical activity (sEMG) of cervical and masticatory system muscles.

BACKGROUND: Coexistence of temporomandibular joint discomfort along with cervical spine disorders is quite common, and is associated with many limitations and adverse symptoms for the patient. Both diagnostics and treatment of these ailments are difficult, and in many cases, the effects of therapy are not satisfactory. This study assessed the impact of a 3-week neck-only rehabilitation programme without direct intervention in the craniofacial area on the bioelectric activity of both the cervical spine and muscles in the craniofacial area among patients with idiopathic neck pain who do not report TMJ pain. DESIGN: A parallel group trial with follow-up; Setting: Rehabilitation Clinic. METHODS: Twenty five patients experiencing idiopathic neck pain underwent the 3-week rehabilitation programme. Thirty five age-matched subjects with no cervical spine and temporomandibular joint (TMJ) dysfunctions were control group. At baseline and after 3 weeks the cervical and craniofacial area muscles' bioelectrical activity (sEMG) was evaluated. RESULTS: In the experimental group during cervical flexion, a significant decrease of sEMG amplitude was noted in the right (mean 25.1 µV; 95% CI: 21.5-28.6 vs mean 16.8 µV; 95% CI: 13.8-19.7) and left (mean 25.9 µV; 95% CI: 21.7-30.0 vs mean 17.2 µV; 95% CI: 13.6-20.7) Sternocleidomastoid as well as a significant increase in sEMG amplitude of the right (mean 11.1 µV; 95% CI: 7.9-14.2 vs mean 15.7 µV; 95% CI: 12.1-19.2) and left (mean 15.3 µV; 95% CI: 11.9-18.6 vs mean 20.2 µV; 95% CI: 15.7-24.2) Upper Trapezius muscles. In the experimental group, after therapy right and left Sternocleidomastoid, Temporalis Anterior and Masseter muscles presented lower fatigue levels. CONCLUSIONS: Three weeks of rehabilitation without any therapeutic intervention in temporomandibular joint significantly decreased the bioelectrical activity of the neck and craniofacial muscles while improving the muscle pattern of coactivation in participants with idiopathic neck pain who do not report temporomandibular joint pain. These observations could be helpful in the physiotherapeutic treatment of neck and craniofacial area dysfunctions. TRIAL REGISTRATION: ID ISRCTN14511735-retrospectively registered.

Influence of the upper joint surface and synovial lining in the outcome of chronic closed lock of the temporomandibular joint treated with arthroscopy.

PURPOSE: Temporomandibular joint (TMJ) arthroscopy has been reported to be an effective and reliable technique for the treatment of chronic closed lock (CCL) of the TMJ. The purpose of the present study was to evaluate whether the status of the joint surface and the synovial lining directly visualized with arthroscopy could determine postoperative results in patients with CCL of the TMJ. MATERIALS AND METHODS: In all, 257 of 500 patients (344 joints) fulfilled the inclusion criteria for CCL of the TMJ. Of these patients, 172 with unilateral TMJ involvement were finally selected for the study. Synovitis and chondromalacia were chosen as the main features for evaluation of the joint surface and synovial lining. Two groups of patients were established: 1) patients with scarce affectation (synovitis grades I-II and chondromalacia grades I-II); and 2) patients with severe affectation (synovitis grades III-IV and/or chondromalacia grades III-IV). Pain and maximal interincisal opening were chosen as dependent variables. All patients were assessed at 1, 3, 6, 12, and 24 months postoperatively. The paired-samples Student's t test was used to compare mean values for pain (using a visual analog scale) and maximal interincisal opening (MIO) both pre- and postoperatively. The Student's t test for unpaired data was applied for the statistical analysis. A P value less than .05 was considered statistically significant. RESULTS: Synovitis grades I-II were arthroscopically observed in 87 (50.58%) patients, whereas synovitis grades III-IV were present in 72 (41.86%) patients. Chondromalacia grades I-II were arthroscopically observed in 66 (38.37%) patients, whereas chondromalacia grades III-IV were present in 54 (31.39%) patients. A statistically significant decrease in pain (P < .001) with a parallel increase in mouth opening (P < .001) after arthroscopy was observed for patients with synovitis I-II, synovitis III-IV, chondromalacia I-II, and chondromalacia III-IV during the whole follow-up period. A significant difference (P = .01) in relation to VAS score was observed between patients with synovitis I-II and patients with synovitis III-IV at month 6 postoperatively. However, this difference did not persist during the rest of the follow-up period, as was the case in relation to mouth opening. No significant differences were observed in relation to decrease of pain and increase of MIO between patients with chondromalacia I-II and patients with chondromalacia III-IV at any time during the follow-up period. Although mean values for pain were lower in patients with synovitis I-II plus chondromalacia I-II in comparison to patients with synovitis III-IV plus chondromalacia III-IV for the whole follow-up period, no statistical significant differences were observed. In relation to the increase in mouth opening, slightly higher values were observed for patients with synovitis I-II plus chondromalacia I-II, although no statistical differences were observed with regard to patients presenting with synovitis III-IV plus chondromalacia III-IV. CONCLUSION: A significant decrease in pain with a parallel increase in MIO was achieved from month 1 postoperatively in patients with any grade of synovitis and/or chondromalacia. No statistical difference in pain or function was observed between patients with scarce involvement of the joint surface and the synovial lining and patients with severe involvement after arthroscopy.

Juvenile idiopathic arthritis (JIA): a screening study to measure class II skeletal pattern, TMJ PDS and use of systemic corticosteroids.

OBJECTIVE: To screen patients with oligoarticular and polyarticular forms of Juvenile Idiopathic Arthritis (JIA) to determine (i) the severity of their class II skeletal pattern; (ii) temporomandibular joint signs and symptoms and (iii) use of systemic corticosteroids. DESIGN: Cross-sectional screening. SUBJECTS AND SETTING: Sixty-eight children with JIA aged between 9 and 16 years old who were screened at four regional treatment centres in the UK. METHOD: Patients were screened clinically and radiographically for the presence of class II skeletal pattern and temporomandibular (TMJ) pain dysfunction syndrome. In addition, the JIA sub-type and history of disease activity and medication were recorded. MAIN OUTCOME MEASURES: Class II skeletal pattern, TMJ signs and symptoms, use of systemic corticosteroids. RESULTS: The mean ANB values were 4.2 degrees (SD = 2.9 degrees) in the oligoarticular group and 5.1 degrees (SD = 3.8 degrees) in the polyarticular group. Just under one-third of children had a moderate or severe class II skeletal pattern and a further quarter of children had a mild class II skeletal pattern. Clinical signs and symptoms of temporomandibular joint pain dysfunction syndrome were low (<20%), except for crepitus and click which affected between 24 and 40% of JIA children. Radiographically, 57% of oligoarticular and 77% of polyarticular cases exhibited condylar erosion. Use of systemic corticosteroids varied between centres, but overall, was prescribed more in polyarticular cases (P = 0.001). CONCLUSIONS: Just under one-third of oligoarticular and polyarticular JIA patients exhibited a moderate or severe class II skeletal pattern. It is, therefore, likely that any future clinical trial to investigate the effect of functional appliance treatment in JIA patients, will need multicentre co-operation to fulfil potential sample size requirements. Clinical signs and symptoms of temporomandibular joint pain dysfunction syndrome were low except for crepitus and click. However, radiographic evidence of condylar erosion was high particularly in the polyarticular group. Use of systemic corticosteroids was prescribed more in polyarticular cases and this is likely to reflect the severity of the disease.

MMP-7 and MMP-9 are overexpressed in the synovial tissue from severe temporomandibular joint dysfunction.

Matrix metalloproteinases (MMPs) are tissue-enzymes that play a key role during the remodeling process, such as in inflammatory diseases. MMP-7 and MMP-9 have been shown to be implicated in extracellular matrix homeostasis and in joint disc remodeling. The objective of this study was to determine the relation of MMP-7 and MMP-9 expression with severe temporomandibular joint dysfunction, in particular with anterior disk displacement without reduction (ADDwoR), using an immunohistochemical approach. Therefore, twenty human temporomandibular synovia in the test group and ten in the control group were collected. The results showed there was a statistically significant difference (P<0.001) for morphometric and densitometric analysis of both detected MMPs in control and test groups. In conclusion, MMP-7 and MMP-9 were overexpressed in the synovial tissue of patients with ADDwoR.

Diagnosis of temporomandibular dysfunction syndrome--image quality at 1.5 and 3.0 Tesla magnetic resonance imaging.

The purpose of this study was to examine the differences in expert ratings of quality of magnetic resonance images (MRI) of the temporomandibular joint in 24 patients with suspected anterior disc displacement examined in randomized order at 1.5 and 3.0 T. Parasagittal (closed and opened mouth) and paracoronal sections were performed with a surface coil. Two experienced examiners blinded to patient status and type of MRI diagnosed the images according to position of condyle, position and changes in the signal, and disc shape. In addition, perceptibility of position and disc shape were assessed. A highly significant difference in the perceptibility of disc shape (P < 0.001) and position (P < 0.001) was obtained. With comparable examination sequences and identical resolution, the 3.0 T MRI of the temporomandibular joint increases the perceptibility of joint structures.

[Myogenous temporomandibular pain: treat with care!]. / Myogene temporomandibulaire pijn: behandelen met aandacht!

For the treatment of myogenous temporomandibular pain, a clinician can choose from among a wide variety of possibilities. Unfortunately, a paper summarizing the effectiveness of all these forms of treatment does not yet exist. The aim of this paper is to provide specific advice for dentists concerning the treatment of patients with myogenous temporomandibular pain by means of a systematic review of the relevant literature. The results of this review of the literature suggest that all forms of treatment selected, including treatment with placeboes, are equally effective in reducing myogenous temporomandibular pain. In order to avoid liability issues, it is advisable to choose for a restrained, reversible form of treatment. The dentist and the patient must, in this respect, be aware that the pain can continue after treatment (albeit at a reduced level) or can return after a period of time.

Magnetic resonance imaging evaluation of temporomandibular joint derangement in symptomatic and asymptomatic patients.

OBJECTIVE: To highlight the importance of MRI in evaluation of the tempromandibular joint (TMJ). METHODS: The MRI examination was performed at King Khalid University Hospital, Riyadh, Saudi Arabia with the approval from the local ethics committee, on 34 patients (68 joints) between January 2006 and November 2007, in which 10 were considered asymptomatic subjects (control). The remaining had symptoms and signs of TMJ pain or dysfunction, including limitation of movement and clicking. All our subjects were examined in both closed and open mouth position. Images were obtained by 1.5-T MRI system, in oblique sagittal plane utilizing 3 pulse sequences including T1 and T2 spin-echo, and spoiled gradient recall sequences. The evaluation of the meniscal disc configuration and position was carried out by 2 radiologists. RESULTS: Sixteen out of 20 joints of asymptomatic subjects were normal. In the other 2 asymptomatic subjects, the MRI showed anterior disc displacement with reduction in 3 joints, and degenerative changes in 2 joints. Out of the 48 symptomatic joints, 26 (45%) joints were considered normal, while the other 22 joints showed anterior dislocation without reduction. Degenerative joint disease was also seen in 18 joints. CONCLUSION: The MRI with the use of surface coils markedly improves the delineation of internal derangement of the TMJ, therefore, it enhanced the capability of detecting certain abnormalities, which proved to have a statistical significance in symptomatic patients.

Avaliação psicossocial e disfunção temporomandibular em graduandos em Odontologia / Evaluación psicosocial y disfunción temporomandibular en estudiantes de pregrado en Odontología / Psychosocial evaluation and temporomandibular dysfunction in undergraduate Dentistry students

O presente estudo objetivou analisar a ocorrência de fatores psicossociais e disfunção temporomandibular (DTM) em graduandos em Odontologia. Realizou-se um estudo transversal, quantitativo, descritivo e analítico. Para a coleta de dados foram utilizados 3 questionários validados, a fim de avaliar o senso de coerência (SOC), ansiedade, depressão e DTM dos discentes, além de perguntas relacionadas ao desenvolvimento acadêmico. Houve adesão de 108 estudantes, 75% do sexo feminino e 49,1% se autoavaliaram com sintomas de DTM. Aproximadamente 36% obtiveram níveis baixos de ansiedade, sendo maior nas mulheres. A maioria encontra-se satisfeito com o desempenho acadêmico, apesar da dificuldade de aprendizado, insatisfação com a rotina e medo de falar em público. A glossofobia foi estatisticamente mais frequente entre as mulheres. Ainda, nos períodos intermediários identificou-se maior insatisfação com a rotina. O SOC médio dos participantes foi de 56,67±8,27 e mostrou-se mais baixo naqueles com elevados níveisde depressão. A ansiedade em níveis altos foi associada com os sintomas de DTM. Portanto, conclui-se que cerca de metade dos discentes de Odontologia apresenta algum sinal de DTM, ansiedade e depressão em níveis baixos, SOC mediano e satisfação com o desempenho acadêmico, apesar das adversidades curriculares (AU).

El presente estudio tuvo como objetivo analizar la aparición de factores psicosociales y Disfunción de Articulación Temporomandibular (DTM) en estudiantes de Odontología. Se realizó un estudio transversal, cuantitativo, descriptivo y analítico. Para la recolección de datos se utilizaron 3 cuestionarios validados, con el fin de evaluar el sentido de coherencia (SC), ansiedad, depresión y DTM de los estudiantes, además de preguntas relacionadas con el desarrollo académico. Participaron 108 estudiantes, 75% mujeres y 49,1% autoevaluados con síntomas de DTM. Aproximadamente el 36% tenía niveles bajos de ansiedad, siendo mayores en las mujeres. La mayoría está satisfecha con su rendimiento académico, a pesar de las dificultades de aprendizaje, la insatisfacción con su rutina y el miedo a hablar en público. La glosofobia fue estadísticamente más común entre las mujeres. Además, en los periodos intermedios se identificó mayor insatisfacción con la rutina. El SC promedio de los participantes fue 56,67 ± 8,27 y fue menor en aquellos con altos niveles de depresión. Un alto nivel de ansiedad se asoció con síntomas de DTM. Por lo tanto, se concluye que aproximadamente la mitad de los estudiantes de Odontología presentan algún signo de DTM, ansiedad y depresión en niveles bajos, SC promedio y satisfacción con el rendimiento académico, a pesar de las adversidades curriculares (AU).

The present study aimed to analyze the occurrence of psychosocial factors and temporomandibular dysfunction (TMD) in undergraduate Dentistry students. A cross-sectional, quantitative, descriptive and analytical study was accomplished. For data collection, 3 validated questionnaires were used, in order to evaluate the students' sense of coherence (SOC), anxiety, depression and TMD, in addition to questions Avaliação psicossocial e disfunção temporomandibular em graduandos em Odontologia related to academic development. 108 students participated, 75% female and 49.1% self-assessed as having TMD symptoms. Approximately 36% had low levels of anxiety, being higher in women. The majority are satisfied with their academic performance, despite learning difficulties, dissatisfaction with their routine and fear to speak in public. The glossophobia was statistically more frequent in women. Also, in intermediate periods it was identified a higher level of dissatisfaction with routine. The sense of coherence was 56,67± 8,27 and it demonstrated lower in those with high levels of depression. The anxiety in high levels was associated with DTM symptoms. Therefore, it is concluded that nearly half of Dentistry students present any of DTM symptoms, anxiety and depression in lower levels, median SOC and satisfaction with academic performance, despite curricular adversities (AU).

Myofascial Pain: Ultrasound Width of the Masseter Muscle.

AIMS: To determine whether subjects with temporomandibular disorders (TMD) manifesting as chronic myofascial pain (MFP) involving the masseter muscle present with significantly greater masseter muscle width, as evidenced by ultrasound, compared to individuals without MFP. METHODS: A case-control study was carried out. A total of 31 subjects presenting with MFP of the masticatory muscles involving the masseter muscle and 35 controls with TMD but no diagnosis of MFP, matched by age and sex, were included. Ultrasound was used to measure the maximum width of both masseter muscles at the intermediate point between the origin and insertion of the muscle in the light occlusal contact (LOC) position and under maximum contraction. Each side was analyzed separately. Means were compared by using single-factor analysis of variance and Mann-Whitney U test; P < .05 was considered to reflect statistical significance. RESULTS: In the study group, the right masseter muscle had a mean ± standard deviation width of 8.6 ± 1.8 mm under LOC (controls: 8.6 ± 1.6 mm; P = .85) and 11.5 ± 2.1 mm under maximum contraction (controls: 11.7 ± 1.9 mm; P = .86). The analagous measures in the left masseter muscle were 8.6 ± 1.6 mm under LOC (controls: 8.2 ± 1.5 mm; P = .42) and 11.3 ± 1.8 mm under maximum contraction (controls: 11.5 ± 1.8 mm) (P = .79), respectively. The increase in width of the right masseter muscle was 2.9 ± 2.1 mm (controls: 3.1 ± 1.2 mm; P = .67) in absolute terms and 1.4 ± 0.3 mm (controls: 1.4 ± 0.2 mm; P = .91) in relative values (width at maximum contraction/LOC width). In the case of the left masseter muscle, the respective values were 2.8 ± 1.7 mm (controls: 3.2 ± 0.9 mm; P = .25) and 1.3 ± 0.2 mm (controls: 1.4 ± 0.1 mm; P = .32). CONCLUSION: There were no statistically significant differences in masseter muscle width between MFP subjects and control subjects under LOC conditions or maximum contraction. The increase in width under maximum contraction was likewise not significantly different between the groups.

Estradiol upregulates voltage-gated sodium channel 1.7 in trigeminal ganglion contributing to hyperalgesia of inflamed TMJ.

BACKGROUND: Temporomandibular disorders (TMDs) have the highest prevalence in women of reproductive age. The role of estrogen in TMDs and especially in TMDs related pain is not fully elucidated. Voltage-gated sodium channel 1.7 (Nav1.7) plays a prominent role in pain perception and Nav1.7 in trigeminal ganglion (TG) is involved in the hyperalgesia of inflamed Temporomandibular joint (TMJ). Whether estrogen could upregulate trigeminal ganglionic Nav1.7 expression to enhance hyperalgesia of inflamed TMJ remains to be explored. METHODS: Estrous cycle and plasma levels of 17ß-estradiol in female rats were evaluated with vaginal smear and enzyme linked immunosorbent assay, respectively. Female rats were ovariectomized and treated with 17ß-estradiol at 0 µg, 20 µg and 80 µg, respectively, for 10 days. TMJ inflammation was induced using complete Freund's adjuvant. Head withdrawal thresholds and food intake were measured to evaluate the TMJ nociceptive responses. The expression of Nav1.7 in TG was examined using real-time PCR and western blot. The activity of Nav1.7 promoter was examined using luciferase reporter assay. The locations of estrogen receptors (ERα and ERß), the G protein coupled estrogen receptor (GPR30), and Nav1.7 in TG were examined using immunohistofluorescence. RESULTS: Upregulation of Nav1.7 in TG and decrease in head withdrawal threshold were observed with the highest plasma 17ß-estradiol in the proestrus of female rats. Ovariectomized rats treated with 80 µg 17ß-estradiol showed upregulation of Nav1.7 in TG and decrease in head withdrawal threshold as compared with that of the control or ovariectomized rats treated with 0 µg or 20 µg. Moreover, 17ß-estradiol dose-dependently potentiated TMJ inflammation-induced upregulation of Nav1.7 in TG and also enhanced TMJ inflammation-induced decrease of head withdrawal threshold in ovariectomized rats. In addition, the estrogen receptor antagonist, ICI 182,780, partially blocked the 17ß-estradiol effect on Nav1.7 expression and head withdrawal threshold in ovariectomized rats. ERα and ERß, but not GPR30, were mostly co-localized with Nav1.7 in neurons in TG. In the nerve growth factor-induced and ERα-transfected PC12 cells, 17ß-estradiol dose-dependently enhanced Nav1.7 promoter activity, whereas mutations of the estrogen response element at -1269/-1282 and -1214/-1227 in the promoter completely abolished its effect on the promoter activity. CONCLUSION: Estradiol could upregulate trigeminal ganglionic Nav1.7 expression to contribute to hyperalgesia of inflamed TMJ.