Analysis of Factors Leading to Occlusal Disorders in Patients with Intact Dental Arches and Orthognathic Bite Type

Disorders of the physiological closure of the dental arches are quite often identified during examinations of dental patients. There is a position among several dental researchers who believe that occlusal disorders are a common cause of dysfunctions of the temporomandibular joint, masticatory muscles, periodontal diseases, manifesting with pain symptoms of various kinds. Factors leading to the formation of occlusal disorders of the dental arches include underdevelopment of the jaws in children, disturbances in the spatial position of the body, defects in the hard tissues of the teeth, as well as defects, anomalies, and deformations of the dental arches. There are research data proving that the factors leading to occlusal disorders in patients with intact dental arches and an orthognathic bite type occur in 84% of cases. Among them are the simultaneous and difficult eruption of third molars, a reduction in the area of occlusal contacts, and irrational restoration of defects in the hard tissues of the posterior teeth with direct composite restorations. It is necessary to develop objective criteria when analyzing the functionality of the closure of dental arches for the timely detection and prevention of the development of occlusal disorders in patients with intact dental arches and an orthognathic bite type.

Introduction

Examination of patients with intact dental arches and temporomandibular joint (TMJ) dysfunctions showed that in 42% of cases, the examined individuals had an orthognathic type of dental occlusion. It is also known that the presence of an orthognathic bite in patients does not exclude the detection of periodontal diseases, hard tissue defects, and irrational direct restorations of the occlusal surface of the posterior teeth. The concept of domestic specialists, as well as specialists from the American Association studying TMJ diseases, who believe that occlusal disorders are the main etiological factor that can lead to dysfunction of the stomatognathic system in its various manifestations, is widely accepted in modern dental science and practice.

Clinical manifestations of occlusal disorders are multifaceted and depend on a number of accompanying factors, such as the condition of the masticatory muscles, the structural and functional features of the TMJ, disturbances in the spatial position of the body, and the psycho-emotional and somatic state of the patient.

The plan for a comprehensive examination of patients with occlusal disorders, TMJ dysfunctions, and masticatory muscle issues in modern conditions requires conducting studies such as axiography, occlusography, electromyography of masticatory muscles, and magnetic resonance imaging of the TMJ. However, despite the high diagnostic value of each of the mentioned methods, the entire set of diagnostic procedures is rarely performed for each examined patient, there is no unified algorithm for comprehensive examination, and there is no single scheme for interpreting the data obtained during the examination.

Research objective: to increase the effectiveness of identifying factors leading to occlusal closure disorders in patients with intact dental arches and an orthognathic bite.

Materials and methods of research.

From 2006 to 2014, we conducted a clinical examination of 210 patients with intact dental arches, an orthognathic bite, and occlusal disorders who sought help at the Department of Orthopedic Dentistry of Stavropol State Medical University. Among all 210 examined patients with occlusal disorders, three groups were identified.

The first group consisted of 121 (57.6%) patients with intact dental arches, orthognathic bite type, unchanged or rationally restored occlusal surfaces with restorative materials (29 men, 92 women).

The second group included patients with an orthognathic bite type, small length included defects of the dental arches and/or disruption of the occlusal surface of one or several posterior teeth, or with multiple irrational restorations of defects in the occlusal surfaces of posterior teeth – 26 people (12.3%), 23 men, 3 women.

The third group consisted of patients with an orthognathic bite type, intact dental arches, with dysfunctions of the TMJ and masticatory muscles – 63 (30%) people, 42 men, 21 women.

The examination included a clinical study, EMG of the masticatory muscles, recording individual movements of the lower jaw, and determining the area of occlusal contacts (OC).

Based on the analysis of the obtained data from all conducted research methods, conclusions were made about the functional state of the dental and jaw system, causal relationships in the development of various pathological conditions were identified, a diagnosis was established, and a treatment strategy was chosen.

The conducted research allowed for the identification of symptoms, the degree of expression of occlusal, joint, and muscular disorders in patients with intact dental arches and an orthognathic bite type, to assess the diagnostic capabilities of methods for graphical registration of lower jaw movements, the method of registering bio-potentials of masticatory muscles, the role of occlusal diagnostics, magnetic resonance imaging, and radiographic methods for studying the condition of the TMJ in a comprehensive examination.

Results of the conducted research

Disruption of the occlusal relationships of the dental arches leads to a disturbance of the centric position of the lower jaw relative to the upper jaw, which is revealed by clinical research methods and confirmed by radiographic and magnetic resonance studies of the TMJ.

Moreover, the balance between the masticatory muscles on the right and left sides is disrupted, forming a habitual side for chewing food. The activity of the temporal muscles during chewing and at rest exceeds the bioelectrical activity in the masticatory muscles themselves, as confirmed by the data on the registration of their bio-potential amplitudes with closed dental arches in the position of central occlusion – on the right 448.3±25.8 µV, on the left 588.3±35.8 µV. The amplitude of the bio-potentials of the masticatory muscles themselves on the right is 221.3±29.5 µV, on the left 238.3±53.7 µV, respectively.

The reduction of the amplitude of bioelectric potentials of the masticatory muscles and the asynchrony of their work is associated with pain phenomena prevailing on one side, with occlusal obstacles on one side, and with the established stereotype of unilateral chewing of food. The bioelectric activity (BEA) of the masticatory muscles is higher than the activity of the temporal muscle during jaw clenching in habitual occlusion by 159.2±23.4 µV.

In patients of the third group, disturbances in the synchronization of contraction of paired masticatory muscles were found, especially in patients with shifts of the lower jaw to one side, with phenomena of deflection and deviation. BEA is higher on the side with worse conditions for chewing food.

The data from our studies are consistent with the results of studies by Yu.A. Petrosov, 1996; A.Ya. Vyazmin, 1999; V.A. Khatova, I.L. Khatova, 2002; in that the violation of occlusal relationships of the dental arches leads to the development of dysfunctions of the TMJ and masticatory muscles, disruption of the neuromuscular complex function, pain phenomena, and disturbances in chewing function. These factors are interrelated and mutually condition each other.

The results of the calculation of the area of the OC in patients of the main and control groups showed that the average area of the OC was 281.8±50.6 mm² (p<0.05).

The analysis of the occlusal relationships of the teeth and dental arches of patients in the control and main groups was conducted on diagnostic models of the jaws using an individual jaw articulator (IJA). The use of the IJA allows for the greatest effectiveness in identifying supercontacts when occluding the dental arches of patients in the control and main groups. The concept of stereographic copying when setting up the IJA allows avoiding the digital expression of the parameters of the movements of the lower jaw, arbitrarily orienting the jaw models in the interframe space of the articulator, thus avoiding the labor-intensive procedure of using a facebow and the errors associated with its application.

The comprehensive treatment conducted, in combination with hardware treatment, was effective in 54% of patients. Control examinations after 6 months, 1-2 years showed no clinical signs of TMJ dysfunction and masticatory muscle dysfunction in patients who underwent comprehensive treatment. During the observation period, patients with intact dental arches, an orthognathic bite type, and incomplete simultaneous eruption of third molars showed supercontacts, signs of TMJ dysfunction, and masticatory muscle dysfunction, the appearance of which was due to the processes of tooth eruption. A repeated course of comprehensive treatment for TMJ dysfunction and masticatory muscle dysfunction achieved a stable remission during a 4-year follow-up. During the control comprehensive examination, no signs of TMJ dysfunction and masticatory muscle dysfunction were found.

The individual approach in the treatment of patients with occlusal disorders combined with dysfunctions of the TMJ and masticatory muscles depended on the severity of the TMJ and masticatory muscle disease and the clinical situation in the oral cavity.

In the treatment of patients with occlusal disorders combined with moderate and severe dysfunctions of the TMJ and masticatory muscles, it is necessary to conduct medication, physiotherapy, and manual therapy during occlusal correction. The preliminary stage included normalizing the spatial position of the lower jaw relative to the upper jaw, occlusal correction, restructuring the myotatic reflex, and temporary prosthetics against the background of pharmacological, manual, and physiotherapeutic treatment. The next stage, after eliminating or compensating for the dysfunction of the TMJ and masticatory muscles, involved final prosthetics. Preference in the prosthetics of patients with moderate and severe dysfunctions of the TMJ and masticatory muscles was given to opposing monolithic orthopedic structures in the lateral sections, with a pronounced occlusal relief. The modeling of the chewing surfaces of orthopedic structures was carried out in the AICH articulator, taking into account the individual parameters of the biomechanics of the lower jaw and creating multiple occlusal contacts in all phases of the chewing cycle.

Discussion of the Results Obtained

The developed tactics for diagnosing and treating patients with intact dental arches, orthognathic bite type, and pronounced occlusal disorders, based on clinical, functional, magnetic resonance, and radiographic research methods, allow for the determination of an individual approach in restoring functional occlusal contacts of the dental arches, while simultaneously compensating for the disorders that have occurred in the TMJ and masticatory muscles. The system of early diagnosis of occlusal disorders should be based on identifying signs of occlusal disorders and factors affecting the closure of the dental arches.

The creation of occlusal relationships that harmoniously combine with the function of the masticatory muscles and TMJ, a prolonged period of remission, the absence of complications and recurrence of the disease in the near and distant future were the criteria for the effectiveness of the developed scientifically justified individual tactics for diagnosing and treating patients with functional occlusion disorders.

The analysis of 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 during clinical 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 themselves, 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.

Conclusions

1. The early diagnosis system for occlusal disorders should be based on identifying signs of occlusal disorders and factors affecting the closure of the dental arches.

2. Clinical examination of patients with intact dental arches and occlusal disorders should include a method for determining the area of occlusal contacts, electromyography of the masticatory muscles, and recording movements of the lower jaw.

3. Restoration of defects in the hard tissues of the posterior teeth affecting the occlusal surface should be carried out using abrasion-resistant indirect restorations with modeling of the occlusal relief according to the individual characteristics of the structure and function of the temporomandibular joint and masticatory muscles of each patient.

Authors: Dolgalyev A.A., Bragareva N.V.

References

1. Antonik M.M. Computer technologies for comprehensive diagnosis and treatment of patients with occlusion pathology complicated by muscle-joint dysfunction: dissertation for the degree of candidate of medical sciences / M.M. Antonik. – Moscow, 2012. – 299 p.
2. Dolgalyev A.A. Comprehensive diagnosis of occlusal disorders in patients with temporomandibular joint pathology // Bulletin of New Medical Technologies. – Tula. – 2008. – Vol. 15. - No. 2. – P. 226-228.
3. Dolgalyev A.A. Comprehensive examination and treatment of a patient with pronounced occlusal disorders. / A.A. Dolgalyev, E.A. Bragin // Modern Orthopedic Dentistry. – 2007. - No. 7. – P. 17-20.
4. Kleinberg I. Occlusion and clinical practice. / I. Kleinberg, R. Jager // MEDpress-inform. – 2008. – 200 p.
5. Lebedenko I.Yu. Clinical methods for diagnosing functional disorders of the dental-jaw system, / I.Yu. Lebedenko, S.D. Arutyunov // Medpress. – 2008. – 113 p.
6. Cooper B, Kleinberg I:. Establishment of a temporomandibular physiological state with neuromuscular orthosis treatment affects reduction of TMD symptoms in 313 patients. J Craniomandib Pract. – 2008; 26(2):104-117.
7. Cooper B. Diseases of the temporomandibular joint. Dental Market #1. – 2012. – P. 51-58.