TMD and the problem of bruxism. A review

Comparison of ultrasonography-based masticatory muscle thickness between temporomandibular disorders bruxers and temporomandibular disorders non-bruxers

To compare masticatory muscle thickness in patients with temporomandibular disorders (TMDs) during rest and clenching, and by body position, using ultrasonography. This prospective study included 96 patients with TMD (67 females, 29 males; mean age: 40.41 ± 17.88 years): group 1, comprising 66 patients with TMD without bruxism (TMD_nonbruxer), and group 2, comprising 30 patients with concurrent TMD and bruxism (TMD_bruxer). In patients with TMD, bruxism was correlated with the presence of tinnitus, muscle stiffness, sleep problems, psychological stress, and restricted mouth opening. The masseter muscle significantly thickened during clenching (11.16 ± 3.03 mm vs 14.04 ± 3.47 mm, p < 0.001), whereas the temporalis muscle showed no significant increase in thickness from resting to clenching in an upright position (7.91 ± 1.98 vs 8.39 ± 2.08, p = 0.103). Similarly, during clenching in the supine position, the masseter muscle was significantly thicker compared with rest (11.24 ± 2.42 vs 13.49 ± 3.09, p < 0.001), but no significant difference was observed in temporal muscle thickness (8.21 ± 2.16 vs 8.43 ± 1.94, p = 0.464). In comparison between two groups, the average thickness of the masseter muscle was greater among TMD_bruxers than among TMD_nonbruxers in both the upright and supine positions (all p < 0.05). In the generalized lineal model, female sex (B = - 1.018, 95% confidence interval [CI] - 1.855 to - 0.181, p = 0.017) and bruxism (B = 0.868, 95% CI 0.567 to 1.169, p = 0.048) significantly predicted changes in masseter muscle thickness. Female sex (B = - 0.201, 95% CI - 0.299 to - 0.103, p = 0.011), increased age (B = - 0.003, 95% CI - 0.005 to 0.000, p = 0.038), and muscle stiffness (B = - 1.373, 95% CI - 2.369 to - 0.376, p = 0.007) were linked to decreased temporal muscle thickness. Comparing TMD nonbruxer and bruxer muscle thicknesses in upright and supine positions revealed significant increased thickness in the masseter muscle during clenching but not in the temporalis muscle. Masseter muscle thickness varied significantly by sex, body position, and resting/clenching, notably influenced by bruxism. These findings emphasize the relevance of these factors in clinical examinations of patients with TMD.

Biomechanical study of temporomandibular joints of patients with temporomandibular disorders under incisal clenching: A finite element analysis

Temporomandibular disorders (TMD) encompass a collection of pathologies. Within the multitude of etiological factors contributing to TMD, mechanical factors hold significant importance. The aim of this investigation was to assess the magnitude and distribution of stresses encountered by the temporomandibular joints (TMJs) during incisal clenching among TMD patients while also elucidating the mechanical pathogenesis underlying TMD. Ten asymptomatic subjects and ten TMD patients were recruited. The Control, Bilateral, and Unilateral groups were set. The contact stress, maximum principal stress, and minimum principal stresses of TMJ structures among the groups were compared. In addition, comparisons of the contact stress distribution among the groups were adopted. In the Control and Bilateral groups, the magnitudes of stresses (contact stress, maximum and minimum principal stresses) between the right and left sides showed no significant difference (P > 0.05). For unilateral TMD patients,the minimum principal stress on the condyle in the Uni-N group (the normal side) was significantly greater than thatin the Uni-T group (the TMD side)(P = 0.016, mean difference 9.99 MPa [95 %CI: 3.11 to 16.87]). Furthermore, stresses on the condyle and fossa of the patients were significantly greater than those of asymptomatic subjects (P < 0.05). The contact stress distributions were concentrated in the Control group while irregular in the TMD groups. In conclusion, asymmetrical contact stress distributions were observed in unilateral TMD, with excessive stresses on the healthy side. The protection of the healthy TMJ during treatment is recommended for patients with unilateral TMD.

Intraoral myofascial therapy for chronic myogenous temporomandibular disorder: a randomized controlled trial

OBJECTIVE

Studies investigating the efficacy of intraoral myofascial therapies (IMTs) for chronic temporomandibular disorder (TMD) are rare. The present study was an expansion of a previously published pilot study that investigated whether chiropractic IMT and the addition of education and self-care were superior to no-treatment or IMT alone for 5 outcome measures-interincisal opening range, jaw pain at rest, jaw pain upon opening, jaw pain upon clenching, and global reporting of change-over the course of 1 year.

METHODS

Ninety-three participants with myogenous TMD between the ages of 18 and 50 years experiencing chronic jaw pain of longer than 3 months in duration were recruited for the study. Successful applicants were randomized into 1 of 3 groups: (1) IMT consisting of 2 treatment interventions per week for 5 weeks, (2) IMT plus education and "self-care" exercises (IMTESC), and (3) wait-list control. The main outcome measures were used. Range of motion findings were measured by vernier callipers in millimeters, and pain scores were quantified using an 11-point self-reported graded chronic pain scale. Global reporting of change was a 7-point self-reported scale, balanced positively and negatively around a zero midpoint.

RESULTS

There were statistically significant differences in resting, opening and clenching pain, opening scores, and global reporting of change (P < .05) in both treatment groups compared with the controls at 6 months and 1 year. There were also significant differences between the 2 treatment groups at 1 year.

CONCLUSIONS

The study suggests that both chiropractic IMT and IMTESC were superior to no-treatment of chronic myogenous TMD over the course of 1 year, with IMTESC also being superior to IMT at 1 year.

Intra-oral myofascial therapy for chronic myogenous temporomandibular disorders: a randomized, controlled pilot study

OBJECTIVES

Studies investigating the efficacy of intra-oral myofascial therapies (IMT) for chronic temporomandibular disorder (TMD) are rare. The objective of this randomized, controlled pilot study was to compare the effects of IMT and the addition of self-care and education over 6 months on four common TMD outcome measures: inter-incisal opening range, jaw pain at rest, jaw pain upon opening, and jaw pain upon clenching.

PARTICIPANTS

Thirty myogenous TMD participants between the ages of 18 and 50 years, experiencing chronic jaw pain of longer than 3-month duration, were recruited for the present study.

INTERVENTION

INCLUDED PATIENTS WERE RANDOMIZED INTO ONE OF THREE GROUPS: (1) IMT consisting of two treatment interventions per week for 5 weeks; (2) IMT plus 'self-care' involving education and exercises; and (3) wait list control.

MAIN OUTCOME MEASURES

Range of motion findings were measured in millimetres by vernier callipers and pain scores were quantified using an 11-point self-reported graded chronic pain scale. Measurements were taken at baseline, 6 weeks post-treatment, and 6 months post-treatment.

RESULTS

The results showed statistically significant differences in resting, opening, and clenching pain and opening range scores (P<0.05) in both treatment groups compared to control at 6 months. No significant differences were observed between the two treatment groups during the course of the trial.

CONCLUSIONS

This study suggests that IMT alone or with the addition of self-care may be of some benefit in the management of chronic TMD over the short-medium term. A larger scale study over a longer term (1-2 years) may be of further value.

The Significance of Sub-Threshold Symptoms of Anxiety in the Aetiology of Bruxism

Bruxism is the oral parafunctional habit of clenching and grinding the teeth. It occurs mainly unconsciously, diurnally and/or nocturnally. It is considered an important contributory factor in the aetiology of myofascial pain and temporomandibular joint disorders and derangements. The aetiology of bruxism is considered to be multifactorial, involving both physiological and psychological factors. The aim of the study was to examine the relationship between the sub-threshold symptoms of anxiety and bruxism, using a spectrum model. Firstly, levels of anxiety were determined using the Spielberger State Trait Anxiety Inventory (STAI) and the Kessler-10 (K-10). Secondly, a tooth-wear score was determined by means of a clinical examination and dental casts. Thirdly, bruxism was rated on an ordinal scale according to specified criteria. A dualistic trend in the relationship between sub-threshold symptoms of anxiety and bruxism was observed in the results. In approximately half of the subjects with higher than average anxiety scores, bruxistic behaviour was found. This indicates the possibility of two groups with separate relationships. The dentist could play a role in recognizing that a patient may be experiencing anxiety, expressed through bruxism behaviour, and refer the patient for therapy or counselling. An understanding of the psychological factors involved in the aetiology of bruxism could foster a more holistic approach to the treatment of patients with signs of bruxism.

Temporomandibular joint: disorders, treatments, and biomechanics

Temporomandibular joint (TMJ) is a complex, sensitive, and highly mobile joint. Millions of people suffer from temporomandibular disorders (TMD) in USA alone. The TMD treatment options need to be looked at more fully to assess possible improvement of the available options and introduction of novel techniques. As reconstruction with either partial or total joint prosthesis is the potential treatment option in certain TMD conditions, it is essential to study outcomes of the FDA approved TMJ implants in a controlled comparative manner. Evaluating the kinetics and kinematics of the TMJ enables the understanding of structure and function of normal and diseased TMJ to predict changes due to alterations, and to propose more efficient methods of treatment. Although many researchers have conducted biomechanical analysis of the TMJ, many of the methods have certain limitations. Therefore, a more comprehensive analysis is necessary for better understanding of different movements and resulting forces and stresses in the joint components. This article provides the results of a state-of-the-art investigation of the TMJ anatomy, TMD, treatment options, a review of the FDA approved TMJ prosthetic devices, and the TMJ biomechanics.