Evaluation of the lateral pterygoid muscle using magnetic resonance imaging

Objectives: The aims of this study were to evaluate the visibility of the lateral pterygoid muscle (LPM) in temporomandibular joint (TMJ) images obtained by MRI, using different projections and to compare image findings with clinical symptoms of patients with and without temporomandibular disorders (TMD). Methods: In this study, LPM images of 50 participants with and without TMDs were investigated by MRI. The images of the LPM in different projections of 100 TMJs from 35 participants (70 TMJs) with and 15 participants (30 TMJs) without clinical signs and symptoms of TMD were visible and analysed. Results: The oblique sagittal and axial images of the TMJ clearly showed the LPM. Hypertrophy (1.45%), atrophy (2.85%) and contracture (2.85%) were the abnormalities found in the LPM. TMD signs, such as hypermobility (11.4%), hypomobility (12.9%) and disc displacement (20.0%), could be seen in TMJ images. Related clinical symptoms, such as pain (71.4%), articular sounds (30.4%), bruxism (25.7%) and headache (22.9%), were observed. Conclusions: Patients with TMD can present with alterations in the LPM thickness. Patients without TMD also showed alterations, such as atrophy and contracture, in TMJ images. Recognition of alterations in the LPM will improve our understanding of clinical symptoms and pathophysiology of TMD, and may lead to a more specific diagnosis of these disorders. Dentomaxillofacial Radiology (2010) 39, 494-500. doi: 10.1259/dmfr/80928433

The impact of stress and anxiety on the pressure pain threshold of myofascial pain patients

The purpose of this study was to evaluate the influence of stress and anxiety on the pressure pain threshold (PPT) of masticatory muscles and on the subjective pain report. Forty-five women, students, with mean age of 19.75 years, were divided into two groups: group 1:29 presenting with masticatory myofascial pain (MFP), according to the Research Diagnostic Criteria for Temporomandibular Disorders and group 2: 16 asymptomatic controls. An electronic algometer registered the pain thresholds on four different occasions throughout the academic year. To measure levels of stress, anxiety and pain, the Beck Anxiety Inventory, Lipp Stress Symptoms Inventory and Visual Analog Scale (VAS) were used. Three-way anova and Tukey`s tests were used to verify differences in PPT between groups, times and sites. Levels of anxiety and VAS were compared using Mann-Whitney test, while Friedman`s test was used for the within-groups comparison at different times (T1 to T4). The chi-squared and Cochran tests were performed to compare groups for the proportion of subjects with stress (alpha = 0.05). Differences in PPT recordings between time (P = 0.001) and sites (P < 0.001) were detected. Higher levels of anxiety and lower PPT figures were detected at T2 (academic examination) (P = 0.001). There was no difference between groups for anxiety and stress at any time (P > 0.05). The MFP group also has shown significant increase of VAS at the time of academic examination (P < 0.001). External stressors such as academic examinations have a potential impact on masticatory muscle tenderness, regardless of the presence of a previous condition such as masticatory myofascial pain.

Specific orofacial problems experienced by musicians

Background: Patients who play musical instruments (especially wind and stringed instruments) and vocalists are prone to particular types of orofacial problems. Some problems are caused by playing and some are the result of dental treatment. This paper proposes to give an insight into these problems and practical guidance to general practice dentists. Method: Information in this paper is gathered from studies published in dental, music and occupational health journals, and from discussions with career musicians and music teachers. Results: Orthodontic problems, soft tissue trauma, focal dystonia, denture retention, herpes labialis, dry mouth and temporomandibular joint (TMJ) disorders were identified as orofacial problems of career musicians. Options available for prevention and palliative treatment as well as instrument selection are suggested to overcome these problems. Conclusions: Career musicians express reluctance to attend dentists who are not sensitive to their specific needs. General practitioner dentists who understand how the instruments impact on the orofacial structures and are aware of potential problems faced by musicians are able to offer preventive advice and supportive treatment to these patients, especially those in the early stages of their career.

Dental and facial characteristics of patients with juvenile idiopathic arthritis

OBJECTIVE: It has been shown that the temporomandibular joint is frequently affected by juvenile idiopathic arthritis, and this degenerative disease, which may occur during facial growth, results in severe mandibular dysfunction. However, there are no studies that correlate oral health (tooth decay and gingival diseases) and temporomandibular joint dysfunction in patients with juvenile idiopathic arthritis. The aim of this study is to evaluate the oral and facial characteristics of the patients with juvenile idiopathic arthritis treated in a large teaching hospital. METHOD: Thirty-six patients with juvenile idiopathic arthritis (26 female and 10 male) underwent a systematic clinical evaluation of their dental, oral, and facial structures (DMFT index, plaque and gingival bleeding index, dental relationship, facial profile, and Helkimo's index). The control group was composed of 13 healthy children. RESULTS: The mean age of the patients with juvenile idiopathic arthritis was 10.8 years; convex facial profile was present in 12 juvenile idiopathic arthritis patients, and class II molar relation was present in 12 (P = .032). The indexes of plaque and gingival bleeding were significant in juvenile idiopathic arthritis patients with a higher number of superior limbs joints involved (P = .055). Anterior open bite (5) and temporomandibular joint noise (8) were present in the juvenile idiopathic arthritis group. Of the group in this sample, 94% (P = .017) had temporomandibular joint dysfunction, 80% had decreased mandibular opening (P = 0.0002), and mandibular mobility was severely impaired in 33% (P = .015). CONCLUSION: This study confirms that patients with juvenile idiopathic arthritis a) have a high incidence of mandibular dysfunction that can be attributed to the direct effect of the disease in the temporomandibular joint and b) have a higher incidence of gingival disease that can be considered a secondary effect of juvenile idiopathic arthritis on oral health.

A combined approach for the assessment of cell viability and cell functionality of human fibrochondrocytes for use in tissue engineering.

Temporo-mandibular joint disc disorders are highly prevalent in adult populations. Autologous chondrocyte implantation is a well-established method for the treatment of several chondral defects. However, very few studies have been carried out using human fibrous chondrocytes from the temporo-mandibular joint (TMJ). One of the main drawbacks associated to chondrocyte cell culture is the possibility that chondrocyte cells kept in culture tend to de-differentiate and to lose cell viability under in in-vitro conditions. In this work, we have isolated human temporo-mandibular joint fibrochondrocytes (TMJF) from human disc and we have used a highly-sensitive technique to determine cell viability, cell proliferation and gene expression of nine consecutive cell passages to determine the most appropriate cell passage for use in tissue engineering and future clinical use. Our results revealed that the most potentially viable and functional cell passages were P5-P6, in which an adequate equilibrium between cell viability and the capability to synthesize all major extracellular matrix components exists. The combined action of pro-apoptotic (TRAF5, PHLDA1) and anti-apoptotic genes (SON, HTT, FAIM2) may explain the differential cell viability levels that we found in this study. These results suggest that TMJF should be used at P5-P6 for cell therapy protocols.

Secondary Aural Symptoms in Relation to Cranio-Cervical and General Disorders

The present thesis comprises two study populations. The first study sample (SS1) consisted of 411 adults examined and interviewed at three annual visits. The second study sample (SS2) consisted of 1720 adults who filled in a mailed questionnaire about secondary otalgia, tinnitus and fullness of ears. In the second phase of the SS2, 100 subjects with otalgia were examined and interviewed by specialist in stomatognathic physiology and otorhinolaryngology. In the third phase, 36 subjects participated in a randomized, controlled and blinded trial of effectiveness of occlusal appliance on secondary otalgia, facial pain, headache and treatment need of temporomandibular disorders (TMD). The standardized prevalence of recurrent secondary otalgia was 6%, tinnitus 15% and fullness of ears 8%. Aural symptoms were more frequent among young than old subjects. They were associated with other, simultaneous aural symptoms, TMD pain, head and neck region pain, and visits to a physician. The subjects with aural symptoms more often had tenderness on palpation of masticatory muscles and clinical signs of temporomandibular joint than the subjects without. 85% of the subjects reporting secondary otalgia had cervical spine or temporomandibular disorder or both. In SS1, the final model of secondary otalgia included active need treatment for TMD, elevated level of stress symptoms, and bruxism. In SS2, the final models of aural symptoms included associated aural symptoms, young age, TMD pain, headache and shoulder ache. Stabilization splint more effectively alleviated secondary otalgia and active treatment need for TMD than a palatal control splint. In patients with aural pain, tinnitus or fullness of ears, it is important to first rule out otologic and nasopharyngeal diseases that may cause the symptoms. If no explanation for aural symptoms is found, temporomandibular and cervical spine disorders should be rouled out to minimize unnecessary visits to a physician.

Five years of sleep apnea treatment with a mandibular advancement device. Side effects and technical complications

Objective: To determine the variation in prevalence of temporomandibular disorders (TMD), other side effects, and technical complications during 5 years of sleep apnea treatment with a mandibular advancement device. Materials and Methods: Forty patients diagnosed with obstructive sleep apnea received an adjustable appliance at 70% of the maximum protrusion. The protrusion was then progressively increased. TMD (diagnosed according to the Research Diagnostic Criteria for TMD), overjet, overbite, occlusal contacts, subjective side effects, and technical complications were recorded before and a mean of 14, 21, and 58 months after treatment and analyzed by the Wilcoxon test (P Less-than .05). Results: Fifteen patients still used the oral appliance at the 5-year follow-up, and no significant variation in TMD prevalence was observed. Subjective side effects were common, and a significant reduction was found in overjet, overbite, and in the number of occlusal contacts. Furthermore, the patients made a mean of 2.5 unscheduled dental visits per year and a mean of 0.8 appliance repairs/relines per year by a dental technician. The most frequent unscheduled visits were needed during the first year and were a result of acrylic breakage on the lateral telescopic attachment, poor retention, and other adjustments to improve comfort. Conclusions: Five-year oral appliance treatment does not affect TMD prevalence but is associated with permanent occlusal changes in most sleep apnea patients during the first 2 years. Patients seek several unscheduled visits, mainly because of technical complications.

Actualización en los tratamientos alternativos en el síndrome de dolor-disfunción craneomandibular

Realizamos una revisión bibliográfica sobre los diferentes tipos de tratamiento alternativo en aquellos casos en los que fracasa la terapia convencional en el síndrome de dolor-disfunción craneomandibular y en los cuales la cirugía no sea la terapia de elección; haciendo una clasificación actualizada de los mismos, siendo estos: terapia psíquica (terapia de relajación muscular y control y manejo del estrés), terapia física realizada por el propio paciente y asistida por un fisioterapeuta, terapia mecánica (biofeedback electromiográfico, TENS, ionoforesis, ultrasonidos y láser blando) y terapia farmacológica.

Surgical reconstruction of TMJ

Certain situations and pathological processes that arise with temporomandibular joint destruction can only be resolved with surgical reconstructive procedures in order to attempt a functional and anatomical rehabilitation of this joint. Many of these situations can be surgically treated with the patient's own autologous tissues. However, in some patients reconstruction is complex and the use of autologous tissues is unadvisable whereas reconstruction utilizing alloplastic materials may be an appropriate alternative. The following report describes 4 clinical cases in which autologous grafts or Christensen joint prosthesis are employed in temporomandibular joint reconstruction

Study of the effect of oral health on physical condition of professional soccer players of the Football Club Barcelona

Objectives: The objective of this study was to evaluate the oral health status of professional soccer players of F.C. Barcelona and its relation to the incidence of sport lesions. Methods: Thirty professional soccer players were consecutively evaluated in the seasons 2003/4, 2004/5 and 2005/6. A research protocol to assess their oral health was developed. DMFT, Quigley & Hein plaque index (PI), Löe & Silness gingival index (GI), World Health Organization malocclusion index, Ramfjord teeth probing pocket depth (PPD), TMJ examination and history of dental trauma were recorded. All physical injuries sustained by players during the season were documented from F.C. Barcelona medical services. Results: Mean DMFT score was 5.7 (SD 4.1), Quigley & Hein plaque index score was 2.3 (SD 1.1), Löe & Silness gingival index was 1.1 (SD 0.8), and periodontal pocket depth was 1.9 mm (SD 0.3). Pearson"s analysis showed a significant correlation between PI and GI (p<0.01). Nine players (30%) presented bruxism - the same proportion of those with severe malocclusion. Seven (23.3%) players had suffered uncomplicated crown fractures. The mean incidence of physical injuries was 8 (SD 3.4) per player. PI and PPD showed a statistically significant correlation to muscle injuries (p<0.05). Conclusions: Soccer players, despite intensive medical follow-up, have significant oral health problems such as untreated caries, gingivitis or malocclusion, and suffer dental trauma as a result of sports activities. Their physical condition could also be associated to oral health

Psychological stress alters the ultrastructure and increases IL-1β and TNF-α in mandibular condylar cartilage

Psychological factors can be correlated with temporomandibular disorders (TMDs), but the mechanisms are unknown. In the present study, we examined the microstructural changes and expression of proinflammatory cytokines in mandibular condylar cartilage of the temporomandibular joint (TMJ) in a psychological stress animal model. Male Sprague-Dawley rats (8 weeks old, 210 ± 10 g) were randomly divided into 3 groups: psychological stress (PS, N = 48), foot shock (FS, N = 24), and control (N = 48). After inducing psychological stress using a communication box with the FS rats for 1, 3, or 5 weeks, PS rats were sacrificed and compared to their matched control littermates, which received no stress and were killed at the same times as the PS rats. Body and adrenal gland weight were measured and corticosterone and adrenocorticotropic hormone levels were determined by radioimmunoassay. After hematoxylin-eosin staining for histological observation, the ultrastructure of the TMJ was examined by scanning electron microscopy. Transcription and protein levels of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) were evaluated by ELISA and semi-quantitative RT-PCR. The PS group showed a significantly higher adrenal gland weight after 3 weeks of stress and higher hormone levels at weeks 1, 3, and 5. Histopathological changes and thinning cartilage were apparent at weeks 3 and 5. In the PS group, TNF-α increased at 1, 3, and 5 weeks and IL-1β increased significantly after 1 and 3 weeks of stress, and then decreased to normal levels by 5 weeks. Psychological stress increased plasma hormone levels and RT-PCR indicated increased IL-1β and TNF-α expression in the TMJ in a time-dependent manner. These results suggest that cytokine up-regulation was accompanied by stress-induced cartilage degeneration in the mandibular condyle. The proinflammatory cytokines play a potential role in initiating the cartilage destruction that eventually leads to the TMDs.

Effets sur l'articulation temporo-mandibulaire du Twin-Block et d'un appareil myofonctionnel de classe II.

Introduction. Ce projet de recherche consiste en une étude cohorte prospective randomisée visant à évaluer les douleurs ressenties au niveau de l’articulation temporo-mandibulaire (ATM) lors d’une thérapie d’avancement mandibulaire grâce à un appareil fixe, le correcteur de classe II (CC) et d’un appareil amovible, le Twin-Block (TB). Matériels et méthodes. Cette étude comptait 26 patients (11 hommes et 15 femmes), âge moyen de 12ans 10mois (10ans 4mois à 15ans 10mois). Les sujets devaient avoir une malocclusion de classe II et être en croissance, CVM 2 ou 3 (Cervical Vertebral Maturation). Les patients étaient divisés en deux groupes : TB et CC. La douleur était évaluée selon l’axe I de l’examen du RDC/TMD (Research Diagnostic Criteria for Temporomandibular Disorders) à 7 reprises (T0 à T6). De plus, le patient devait remplir un questionnaire, à la maison, sur la douleur ressentie et la médication prise lors des 30 premiers jours. La douleur était évaluée avant l’insertion des appareils (T0), à 1 semaine (T1) post-insertion, 4 semaines plus tard (T2), 8 semaines (T3) où une expansion de 20 tours (environs 5 mm) était débutée, ensuite (T4) (T5) et (T6) chacun à 8 semaines d’intervalles. Les tests statistiques utilisés dans cette étude : le test «Wilcoxon à un échantillon» ainsi que le test «Mann-Whitney à échantillons indépendants ». Résultats et Discussion. La douleur à l’examen clinique est variable mais tend à diminuer avec le temps. Aucune différence, statistiquement significative, ne fut observée entre les 2 groupes en ce qui à trait aux diverses palpations effectuées. Parmi les patients ayant rapporté de la douleur, 40% l’ont ressentie surtout le matin et 63,3% ont dit qu’elle durait de moins d’une heure jusqu’à quelques heures. Conclusion. D’après nos résultats, lors d’une thérapie myofonctionnnelle, il n’y a pas de différence statistiquement significative entre la douleur occasionnée par un Twin-Block et celle produite par un correcteur de classe II fixe au niveau de l’ATM et des muscles du complexe facial.

Effets du port continu de coquilles correctrices Invisalign® sur l’articulation temporo-mandibulaire et les muscles du complexe facial.

INTRODUCTION : L’articulation temporo-mandibulaire (ATM) est un système articulaire excessivement complexe. L'étiologie des désordres temporo-mandibulaires (DTM) est encore incertaine et le lien de cause à effet des traitements orthodontiques en tant que facteur de risque est une question qui a longuement été discutée. Cette étude clinique prospective vise à évaluer les effets à long terme du port continu de coquilles correctrices Invisalign® sur l’ATM et les muscles du complexe facial. MATÉRIELS ET MÉTHODES : L'étude incluait 43 adolescents et adultes âgés entre 13 et 51 ans (25 femmes et 18 hommes). Deux d'entre eux ont été exclus en raison de mauvaise coopération causant l’arrêt du traitement orthodontique. Les effets dans le temps des coquilles sur l'ATM et les muscles du complexe facial ont été évalués en utilisant l’examen du Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD). Le nombre de contractions musculaires durant le sommeil a été mesuré objectivement par enregistrements électromyographiques (EMG) et la fréquence de grincement et de serrement des dents à l’éveil a été rapportée subjectivement par les patients à l’aide de questionnaires. Des mesures répétées ont été effectuées aux temps suivants: avant le début du traitement pour les données contrôles (T1), deux semaines (T2), et six mois (T3) après le début du traitement. Les données numériques ont été analysées par l’analyse de variance (ANOVA) en mesures répétées et la méthode de Brunner-Langer, alors que les données nominales ont été évaluées par le test de Cochran-Mantel-Haenszel. Les résultats ont été considérés significatifs si p < 0.05. RÉSULTATS ET DISCUSSION : Le nombre de contractions musculaires par heure (index) durant le sommeil et leur durée moyenne n’ont pas été statistiquement différents entre les trois nuits d’enregistrement EMG (Brunner Langer, p > 0.005). Cependant, 67 % des participants ont rapporté avoir eu du grincement ou du serrement des dents la nuit au T2 et 64 % au T3 comparativement à 39 % au T1, ce qui était une augmentation significative (Cochran-Mantel-Haenszel, p = 0.0112). Quarante-quatre pour cent des patients ont signalé du grincement ou du serrement des dents pendant le jour au T1, tandis qu'un pourcentage nettement plus élevé de 66 % en a rapporté au T2 et 61 % au T3 (Cochran-Mantel-Haenszel, p = 0.0294). Au T1, 12 % des sujets ont indiqué qu'ils se sont réveillés avec une douleur musculaire, comparativement à 29 % au T2, ce qui était une augmentation significative (Cochran-Mantel-Haenszel, p = 0.0347). Au T2, il y avait une réduction significative des mouvements maximaux de la mandibule dans toutes les directions (ANOVA en mesures répétées, p < 0,05). De plus, il y a eu une augmentation significative du nombre de sites douloureux et de l'intensité de la douleur à la palpation de l'ATM et des muscles faciaux avec l'évaluation du RDC/TMD au T2 en comparaison aux T1 et T3 (Brunner Langer, p < 0,05). CONCLUSION : La présente étude n’a révélé aucun effet des coquilles sur l’activité oro-faciale durant le sommeil au fil du temps mesurée objectivement à l’aide des enregistrements EMG, mais une augmentation significative de la fréquence du grincement et du serrement des dents rapportée subjectivement par les patients au moyen des questionnaires aux T2 et T3. Au T2, il y avait une augmentation significative des symptômes de l'ATM et des muscles du complexe oro-facial, mais ces symptômes sont retournés au niveau initial avec le temps.

Influence of the lateral pterygoid muscle on the growth of the mandibular condilar cartilage

At the end of the last century, a model to explain clinical observations related to the mandibular growth was developed. According to it, the lateral pterigoid muscle (LPM) was one of the main modulators of the differentiation of mesenquimal cells inside the condyle to condroblasts or osteoblasts, and therefore of the growth of the mandibular condilar cartilage (CCM). The main components of the model were the humoral and the mechanical. Nowadays, the humoral would include growth factors such as IGF-I, FGF-2 and VEGF, which seem to be involved in mandibular growth. Since skeletal muscle can secrete these growth factors, there is a possibility that LPM modulates the growth of CCM by a paracrine or endocrine mechanism. The mechanical component derived from the observations that both the blood flow inside the temporomandibular joint (ATM) and the action of the retrodiscal pad on the growth of the CCM, depend, in part, on the contractile activity of the LPM. Despite the fact that there are some results suggesting  hat LPM is activated under conditions of mandibular protrusion, there is no full agreement on whether this can stimulate the growth of CCM. In this review, the contributions and limitations of the works related to mandibular growth are discussed and a model which integrates the available information to explain the role of the LPM in the growth of the CCM is proposed.