The Role of Occlusal Disorders in the Development of Temporomandibular Joint Diseases, Masticatory Muscle Dysfunctions, and Periodontal Diseases

An analysis was conducted on the relationship between occlusal disorders and dysfunctions of the temporomandibular joint, masticatory muscles, and periodontal diseases in patients with intact dental arches. The area of occlusal contacts was used as an objective criterion in analyzing the functionality of the dental arch closure. Electromyography was employed to analyze the functional state of the temporomandibular joint and masticatory muscles. A randomized controlled trial was conducted to study the impact of occlusal disorders on the development of dysfunctions of the temporomandibular joint, masticatory muscles, and periodontal diseases. Removable splints that alter the occlusal relationships of the dental arches and splints that maintain existing occlusal relationships were used to treat patients with dysfunctions of the temporomandibular joint, masticatory muscles, and periodontal diseases. According to the results of non-parametric correlation analysis, a connection was established between the restoration of the function of the temporomandibular joint, masticatory muscles, and the normalization of occlusal relationships.

Introduction

Functional disorders of the dental and maxillofacial (stomatognathic) system have various causes and clinical manifestations. There are many viewpoints explaining the pathogenesis of dysfunctions of the temporomandibular joint (TMJ), masticatory muscles, periodontal diseases, and the role of occlusal disorders in their development. However, according to the authors I. Klinberg, R. Jager, no randomized controlled trials, which are the "gold standard" of statistical validity, have been conducted on harmonious natural and restored occlusion.

At different times, independently of each other, researchers with co-authors Mc. Namara (1995), Tsukiyama (2001), reported that as a result of their studies, there was no reliable confirmation of the mutual influence of occlusal disorders and dysfunctions of the TMJ, masticatory muscles, and periodontal diseases. The authors found that patients with TMJ dysfunction and without joint pathology exhibited the same occlusal characteristics, and the occlusal status of patients did not correlate with the radiographic picture of the TMJ condition, while changes in the condylar heads were not related to the number of lost teeth. The authors explain this phenomenon by the pronounced adaptive capabilities of the human stomatognathic system to frequent and constant changes occurring in the dental arches.

In contrast to the theory presented above, the viewpoint of domestic authors Lebedenko I.Yu., Arutyunov S.D., Antonik M.M., Abolmasov N.N., Petrosov Yu.A., who interpret occlusal disorders as the main etiological factor capable of leading to compensated or decompensated forms of dysfunction of the stomatognathic system in its various manifestations, is widely accepted. The overwhelming majority of doctors, including specialists from the American Association studying TMJ disorders, believe that occlusion plays an important role in the development of dysfunctions of the TMJ, masticatory muscles, and periodontal diseases.

Research objective: to determine the role of occlusal disorders in the development of temporomandibular joint dysfunction, masticatory muscles, and periodontal diseases.

Research tasks: to develop objective criteria for assessing the quality of occlusion of the upper and lower jaws, to determine the frequency of factors causing occlusal discrepancies in patients with temporomandibular joint dysfunction, masticatory muscles, and periodontal diseases.

Materials and Methods of the Study.

From 2006 to 2013, we conducted a clinical examination of 140 patients with intact dental arches who sought consultative assistance at the Department of Prosthetic Dentistry of StSMU. The age of the patients ranged from 22 to 45 years. Among those who sought help, there were 112 (80%) women and 28 (20%) men. The control group included 45 individuals with an orthognathic bite and intact dental arches, without identified occlusal disorders and pathologies of the TMJ and masticatory muscles. Patients with TMJ dysfunctions, masticatory muscle disorders, periodontal diseases, before and after treatment, were assessed for the area of occlusal contacts, analyzed for electromyographic activity of the masticatory muscles, and evaluated for tooth mobility.

The controlled randomized study was conducted on a group of patients (140 individuals) who were identified with occlusal disorders, TMJ dysfunctions, masticatory muscle disorders, and periodontal diseases. Patients were randomly divided into two groups. In the first group, occlusal correction was performed through selective grinding and removable TMJ splints, myobraces were applied.

In the second group of patients, treatment was conducted using removable dentogingival splints with an open occlusal surface, made on the thermovacuum apparatus Bio-Art, or the Schulte apparatus.

The results of the study were statistically processed on a personal computer using statistical formulas from the MS Excel program. The Kolmogorov-Smirnov test for a single sample was used to check the conformity of the distribution of the initial data to the normal distribution. When the sample distribution differed from the normal, the Dunn, Kruskal-Wallis, and Mann-Whitney tests were applied. To identify the relationship between the studied variables, a correlation analysis was conducted using Spearman's correlation coefficient (a non-parametric correlation coefficient). Differences between groups were considered significant if the p-value was less than 0.05.

Results of the conducted study.

Our studies on the prevalence of occlusal disorders, TMJ dysfunction, masticatory muscles, and periodontal diseases from 2003 to 2013 among students and patients visiting orthopedic, surgical, and orthodontic departments of various dental clinics demonstrate an increase in cases of TMJ dysfunction signs.

According to our observations, occlusal disorders, temporomandibular joint dysfunctions, masticatory muscle disorders, and periodontal diseases are most often accompanied by pain phenomena of varying intensity and nature – in 88% of cases, and noise manifestations when opening and (or) closing the mouth (cracking, clicking) – in 100% of cases. Occlusal disorders in the form of supercontacts in central, anterior, and lateral occlusions are also frequently found in patients with temporomandibular joint dysfunctions – in 99% of cases. However, discomfort when closing the dental arches was noted by 62% of patients.

Analysis of the electromyographic activity of the masticatory muscles in patients with functional occlusion disorders demonstrates that occlusal obstacles lead to a decrease in the bioelectrical activity of all masticatory muscles, except for the lateral pterygoid, which is confirmed by clinical palpation examination.

Occlusal supercontacts lead to a decrease in the bioelectrical activity of the masticatory muscles themselves, an increase in the share of activity of the temporal muscles compared to the masticatory muscles, an exclusive increase in the bioelectrical activity of the lateral pterygoid muscles, and asymmetry in the degree of bioelectrical activity of the masticatory muscles on the right and left.

Our research shows that manifestations of occlusal disorders in the frontal area are focal periodontitis in 34% of cases, manifested by the exposure of the roots of the lower incisors, resorption of interproximal septa, formation of periodontal pockets, and tooth mobility. In the clinical picture of focal periodontitis localized in the area of the lower incisors, occlusal disorders are identified in 100% of cases in the position of anterior occlusion, and in the position of centric occlusion – in 24% of cases. Accompanying the clinical picture of focal periodontitis, in addition to pronounced occlusal disorders, is the crowding of teeth in this area, caused by a lack of space for the entire set of teeth in the dental arch.

A controlled randomized study was conducted on a group of patients (140 people) who were found to have occlusal disorders, TMJ dysfunction, masticatory muscle disorders, and periodontal diseases. Treatment of patients was carried out using TMJ splints, occlusal splints made on the Bio-Art thermovacuum apparatus, myobraces, and Schulte appliances.

Patients were randomly divided into two groups. In the first group, occlusal correction was performed through selective grinding and removable TMJ joint trainers, myobresses were used. In the second group of patients, treatment was conducted using removable gingival splints with an open occlusal surface, made on the Bio-Art thermovacuum machine or the Schulte device.

The results of the analysis of electromyographic studies of the masticatory muscles, occlusal status, and tooth mobility before and after treatment, at 1, 2, and 6 months, showed that treatment of patients with TMJ dysfunctions, masticatory muscle issues, and periodontal diseases without occlusal correction through selective grinding and removable splints with an open occlusal surface using the Schulte device was ineffective. The parameters of bioelectrical activity of the masticatory muscles during the 1, 2, and 6 months of treatment showed no statistically significant differences compared to the parameters obtained before treatment. The average area of occlusal contacts in patients of this group was 124±76.5 mm², which did not significantly differ from the values obtained before treatment. The degree of tooth mobility in patients with periodontal diseases also did not significantly differ from the values obtained before treatment.

In patients who underwent selective grinding and used TMJ joint trainers, myobraces, a statistically significant increase in the area of occlusal contacts (281±23 mm²) was observed, achieving a temporary and force balance of occlusal contacts, improvement in the parameters of the balance of bioelectrical activity of the masticatory muscles, and a reduction in the degree of tooth mobility.

Discussion of the results obtained.

The subjective improvement in the condition of the stomatognathic system noted in 10% of patients who underwent treatment without occlusal correction (7 people receiving treatment without occlusal correction), using Schulte appliances and splints with an open occlusal surface made on the Bio-Art thermovaccum apparatus, can be explained by the placebo effect, as no statistically significant evidence of improvement in the functional state of the stomatognathic system was obtained.

Conclusions

1. In patients with temporomandibular joint dysfunction, masticatory muscle disorders, and periodontal diseases, occlusal disorders were found in 90% (126 out of 140 examined) in central, anterior, and (or) lateral occlusions.
2. Analysis of electromyographic activity of masticatory muscles, occlusal analysis using the T-Scan 3 device, and assessment of tooth mobility showed that treating patients with temporomandibular joint dysfunction, masticatory muscle disorders, and periodontal diseases without correcting occlusal disorders does not lead to objective improvement in the functional state of the stomatognathic system.
3. The use of selective grinding techniques, removable splints that correct occlusal disorders in the treatment of patients with temporomandibular joint dysfunction, masticatory muscle disorders, and periodontal diseases allows for improvement in the indicators of electromyographic activity of masticatory muscles, parameters of occlusal analysis, and reduction in tooth mobility.
4. The use of the Schulte splint in the treatment of patients with temporomandibular joint dysfunction, masticatory muscle disorders, and periodontal diseases provides subjective relief to patients in 10% of cases; however, the therapeutic effect does not have objective statistically significant confirmation supported by the study of electromyographic activity of masticatory muscles and occlusal analysis.

Authors: Bragin E.A., Dolgalev A.A., Bragareva N.V.

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