SuBStAntIAtIon of RElAXInGS plIntuSEd on pAtIEntS wIth thE pARAfunCtIon of ChEwInG muSClES

The researchconducted by us has enabled us to analyze the influence of relaxingsplintson the chewing muscles’ condition of patients with dualfunction and to study the dynamics of the changes EMG-activity of their chewing muscles.

«BioPak», USA), software version. It consists of a block of analog-digital reproducer, amplifier, display, computer block, stimulator and connecting wires. The signal from electrodes is transferred by connecting wires to the preamplifier where partial reinforcement and transformation into digital form takes place. Then the amplified signal goes through the amplifier, where it increases by 1000-10 000 times. This is necessary in order to see the registered signal on the screen. The amplifier also helps to increase the frequency in the range from 25 to 10 000Hts. That registered signal is displayed on the screen in the form of the graph showing dependence of speed of the impulse in the nerve on its sensitivity. In addition, there is a system of accompanying sound synchronized with the reamer rays on the screen. This enables the dentist not only to see, but hear the electrical activity of the muscle. The advantage of this dual control is that small amplitude changes can be easily seen on the screen, and the change in frequency is better perceived by ear.
The study was conducted in isolation from external noise indoors at room temperature. The patient during this study was in the armchair, in half-horizontal position that gives maximum relaxation of masticatory muscles and enables the dentist to work functionally with the chewing muscles.
At the beginning of the study each patient was explained in simple terms the essence and objectives of the procedure, its necessity and safety. We chose the methodology of global functional electromyography and stimulation electromyography.
To register bioelectric potentials we used individuale plate cutaneous electrodes. We began the electromyographic study of masticatory muscle with the palpationional definition of the studied muscle motor point. It is a tight formation and to determine it we ask the patients to clench their teeth with force. We degreased the skin in the projection over the motor point with ethanol and used adhesive tape to fix the electrodes with the gel previously applied to the surface, which improves electrical conductivity. Grounding electrode clip was fixed on the patient's ear.
Besides studying electromyographic activity we carried out electromyography (study of muscular biopotentials which occur in response to stimulation of the nerve or muscle) to determine the "period of silence" and masseter-reflex.
To determine the "period of silence" we asked the patient to clench his teeth with the maximum force. At the same time we applied the pilot to the chin and hammered it at the distance of 10-15 cm. Then we asked the patient to relax the muscles. The study was repeated three times at intervals of 5 seconds. The methodology of the study of the masseter-reflex is the same, but the research is carried out in the state of functional rest of masticatory muscles of the patient.
Results and discussion. We started the electromyographic study of patients to study the proper bioelectrical activity of masticatory and temporal muscles in a state of relative calm. Normally, during this study on the monitor contours could be observed, indicating the absence of voluntary activity in masticatory muscles. In 68 patients (100 %) in the phase of peace functional activity we observed random outbreaks of 0.06 to 1.31 mV for proper chewing muscles, and from 0.11 to 1.51 mV for temporal muscles.
The next step was to study the maximal volitional clench of of jaw what we observed during 3 seconds. The received electromyogram of the patients of the main and control groups belongs to EMG of the first class according to Y. S. Yusevych-interference curve, which is a high-frequency polymorphic activity that occurs randomly during muscle contractions or tension in other muscles. This electromyogram of the patients of the maingroup demonstrated uneven amplitude and frequency of potentials. Increase in the amplitude of the electromyographic activity is due to the reduction of masticatory muscles function.
It is caused by the increasing number of motor units involved in the process of reduction and change in sync bioelectric discharges. Also the patients of the main group demonstrated asymmetry (94.1 %) of the maximum bioelectrical activity in the masticatory and temporal muscles on the left and right sides. The research of arbitrary chewing, universal stimulus for which is hazelnut kernels, allowed us to determine the number of chewing cycles of the patient, to trace the interchange of the sides during chewing, existence of the dominating chewing side.
Research of the one-sided chewing enables us to study the functional activity of one specific muscle. One can see the analysis of the study of the original state of masticatory and temporal muscles in patients in Table 2. This data indicates that patients of the control group have the violations of muscle activity. The analysis of the research of masticatory and temporal muscles of the patients during treatment by relaxation removable splints is shown (after 3 and 6 months) is shown in see Table 2. Determination of the time of "period of silence" is of significant diagnostic value, because its increase is the initial sign of the dysfunction of contraction of masticatory muscles contraction due to changes in segmental brakes. Analyzing the indicators of the "period of silence" of patients one should stress that the "period of silence" of the patients of the control group exceeds (67 %).
The definition of the latency period of the masseter-reflex of masticatory muscles in all patients was 6-8,4mswhich is normal. This shows the preservation of afferent and efferent conduction and integrity of the reflex arc at the level of the brain stem and at the level of the trigeminal nerve.
Conclusions. 1. Indicators of the "period of silence" of the patients exceed normative indicators, which shows the disruption of contraction and relaxation of masticatory muscles due to violation of suprasegmentally inhibitory mechanisms.2. The length of the latent period of the masseter-reflex in the studied patients corresponds to the norm, which shows intactness of the reflex arc of the reflex at the level of the brain stem and at the level of the trigeminal nerve.3. 3 months after the application of the relaxation splints on electromyogram 36 patients had (52.9 %) contours at the state of rest during arbitrary alignment. 39 patients (57.3 %) had alignment of structure and filling of the chewing wave, increase in the number of chewing cycles, smoothing of periods of activity and rest of the masticatory muscles.6 months after the application of relaxation splints on electromyogram in 54 (79.4 %) patients we observed contours at the state of rest. In 57 (83.8 %) patients we observed alignment of structure and filling of chewing wave, increase in the number of chewing cycles, smoothing relations between the periods of activity and rest of masticatory muscles. 59 (86.8 %) patients noted a general improvement in their state and the complete absence of pain in the masticatory muscles, no discomfort.Given the above data of electromyography it should be noted that the use of relaxation splints as an intermediate stage of orthopedic treatment of patients with parafunctions of masticatory muscles is appropriate and desirable. Central nervous system "balances" existing in the patient's occlusal overload through complex reflex connections by programming functional activity of masticatory muscles. Uneven overload of masticatory muscles, reaching the phase of decompensation, forms a stable parafunction of muscles, which may be accompanied by a number of painful and uncomfortable symptoms. Taken into consideration the mechanism of myotactic reflex, and considering the possibility of its adjustment the dentist has the task to achieve the most favorable condition in a patient using relaxation splints. At the next stage of treatment the dentist must keep the result obtained by correcting and stabilizing occlusal relationships and prevent further occurrence of overload of masticatory muscles.