Summary

On the basis of selected cases, evaluation of the usefulness of muscular exercises in rehabili­tation of patients stricken by a dysfunction of the motor system of the chewing organ was accomplished. The assessment of the electric function of chewing muscles together with the registration of mandibular movements with the axiographic Zebris JMA apparatus was made, both before and after muscular therapy. The examination has shown that regardless of micro- or macro-traumatic cause, the set of muscular exercises appropriately selected and dutifully carried out is able to restore full condition of the motor system of the bone-dental structure effectively.

Key words:dysfunction of the temporomandibular joints (TMJ) • muscle activity

Introduction

The proper functioning of the stomatognathic system is achieved by dental and musculo-nervous system har­monious interaction. If either of these two systems fails, it leads to the stomatognathic system’s motor apparatus impairment.

The syndrome of masticatory dysfunctions is a group of civilization diseases with increasing frequency. Epi­demiological studies in recent years, regarding the ele­ments causing functional changes in the stomatognathic system, show that the most important are malocclusion (54%), stress factors (34%), mental disorders (7.1%) and the primal, partly generalized disorder arthritis (4.1%)[11,14,18,22,28].

Dysfunction is often accompanied by various types of parafunctions (e.g. bruxism)[21]. Among the determi­nants that cause dysfunction in the stomatognathic sys­tem most often the following are mentioned: traumatic occlusion, stress, wrong habits, acute and chronic inju­ries, muscles’ dysfunctional features and iatrogenic issues [9,22,31]. Dysfunction of the masticatory motor system persisting for years causes over time occurrence of pain symptoms or painless signs, referred to as dysfunction. The main symptoms of masticatory dysfunction are: pain during mandibular movements, limiting its mobility, and leaping and crackling in the TMJ. It is assumed that at least one of these symptoms occurs in about 90% of the human population. –

One of the early masticatory dysfunction signs is man­dibular mobility model disorder. The study of uninter­rupted articulatory jaw movement is the basis of clinical evaluation of masticatory efficiency

As a rule, diagnostics of stomatognathic system dysfunc­tion is carried out on data from medical inquiry and clini­cal examination: visual, auscultatory and palpable. Due to the increasing prevalence, diversity and growth in the disease process intensity, simple clinical tests seem to be insufficient. The use of modern, often elaborate diagnos­tic techniques becomes indispensable, especially for pa­tients with severe symptoms of stomatognathic system dysfunction, frequently combined with morphological changes [2,3,12,15,22,24].

Medical tests including the muscular system are inte­gral to masticatory efficiency assessment. Clinical eval­uation includes the size of each muscle, its symme­try, determining the level of tension, activity and pain sensitivity. The survey is performed by palpation, but also as static and dynamic function tests. More reli­able muscle function exploration is electromyograph­ic study [4,8]. That allows one to determine numerical values of resting and functional potentials and makes it possible to assess homologous muscles in terms of sym­metry [4,13,30]. The muscular system, responsible for the movements of the jaw, is a geminate system. As a result of some muscles’ contraction and relaxation of antagonistic muscles, the mandible after receiving im­pulses from the nervous system is set in a particular po­sition. Therefore, symmetrical muscular work is one of the most important initiators conditioning the proper functioning of the masticatory system.

Muscles important for the treatment of masticatory movement disorders are mandibular adductors: mas­seter, temporal muscles, internal pterygoid muscle and mandible abductor – external pterygoid muscle, and to a lesser extent, the bottom of the oral cavity muscle, as well as the tongue, throat and palate muscles. The whole layout’s agile functioning, due to the overrid­ing role of the CNS, depends not only on the patient’s psycho-emotional condition, but also on overall health. Physiological and pathological processes, taking place even in tissue located far from the masticatory system, through neural connections, can reach the masticatory system and affect its function. In the literature there have been reported cases of pain transferred to the sto­matognathic system from the chest and even from the abdominal cavity [9]. The management among patients with motor dysfunction of the masticatory organ is an extended, intricate and generally multistage process. Possible therapeutic procedures are very diverse. In dis­eases associated with particular disc displacement, at the forefront lies therapy using the great variety of bite splints. The aim is, inter alia, articular disc reposition­ing, reducing excessive stomatognathic system muscle tension and the restoration of static and dynamic sym­metry in all parts of the system [25].

In episodes with notable severity of disease symptoms caused by dysfunction, pain or acoustic effects, which affect the patient’s psyche, there is often a conscious re­striction of chewing muscle function. Muscular therapy in such cases is sufficient to achieve a satisfactory therapeu­tic effect. Lack of muscle activity is just as harmful to the stomatognathic system components as their hyperactiv­ity in e.g. bruxism. This may lead to shortening of muscle fibres, in extreme cases even to muscle atrophy. Mus­cles’ training, recommended for patients suffering from stomatognathic system macro-injuries, is often the only chance to restore the efficiency of the damaged items.

Description of the cases

Case I

Patient Z.N., aged 20, case history 12/N/2007, reported herself to the Department of Dental Prosthetics, Pomera­nian Medical University, for diagnosis and conservative treatment. The treated woman complained that for ap­proximately four months she had suffered from crackling and skipping movements in the left temporo-mandib­ular joint. Dysfunctional symptoms, in addition to the patient’s discomfort and anxiety, did not cause any pain. Clinical palpable trial indicated no masticatory muscles’ tactile soreness. Masseter and temporal muscles showed no sign of increased tension. Both dental arches were complete with a few fillings, secured type of articula­tion by canines and incisors, no signs of pathological en­counter or occlusal obstacles. The patient was not being treated orthodontically.

On the day of the study major symptoms report­ed were: abduction of the mandible limited and with diffi­culties (26 mm measured with a ruler), with marked right-sided deviation of the mandible in the first movement phase. On the basis of X-rays, according to Schüller a bi­lateral movement reduction of the mandibular head was concluded.

In the functional procedure conducted by Zebris appara­tus, there was an abridgement of abduction movement (27.7 mm) and lateral movements – about 6 mm (Fig. 1, 2).

Figure 1. Recordings of general abduction report using Zebris JMA device

Figure 2. Graphic notation of condylar movement using the Zebris JMA device. A – the right joint; B – the left joint

In the electromyographic study performed using the Ze­bris Dental Bluetooth System for recording and analyz­ing EMG, there was no increased muscle tension or po­tential differences between right and left sides (Fig. 3).

Figure 3. Section of patient’s electromyography broad report (Zebris EMG ) – resting potentials’ values. A – right side, B – left side. Red colour – masseters, green colour – temporal muscles

Moreover, action potentials showed no significant dif­ferences either in terms of value or in the homologous muscles’ symmetry.

Based on the above-mentioned symptoms and test re­sults, the diagnosis was the disturbance model of abduc­tion of the mandible and reduction of mental source. A set of exercises was presented to the patient: training that corrects the jaw’s movable model – opening along the straight line, in front of the mirror and stretching exercis­es to increase mobility of the mandible – gentle strength application coming from the patient’s fingers. As pre­scribed, the instructions had to be performed 2-3 times a day in batches of 15 to 20 repetitions. After six weeks of therapy, a significant improvement was observed. The re­sults of the performed functional research, obtained with the Zebris JMA device, show a marked increase of motion range. The size of the opened mouth was 36.3 mm, which is an increase of nearly 9 mm (Fig. 4A), and lateral mo­tions: right sided – 8.8 mm, left-sided – 7.6 mm.

Figure 4. Graphic recording (Zebris JMA) of patient’s condylar movement after 6 weeks of muscle training: A – opening and lateral movement range, B – motion range of both condylar appendixes in the joints

Case II

Anamnesis: Patient T.M., aged 25, referred to the Depart­ment of Dental Prosthetics, Pomeranian Medical Uni­versity, with pain from the temporomandibular joints. A sore appeared about 2 months previously, in the area of the temporomandibular joints and the two angles of the mandible with indication to the left side. With wide open mouth (yawning) there was noticeable leaping in both TMJs. At the time of examination, after taking non-ste­roid anti-inflammatory drugs the pain disappeared. The patient noticed that after discontinuation of drug treat­ment the aches recurred. Pain symptoms occurred before, but never with such high intensity, which continued for 2 months. The patient associated the fact of worsening symptoms with wide mouth opening while yawning. The biggest annoyance of symptoms occurred in the morning shortly after getting up. During the day the pain intensity diminished, but intensified during chewing.

Clinical examination revealed excessive mobility of the mandible (the interval measured between the cutting edges of upper and lower incisors was 47 mm), the oc­currence of significantly impaired mandible’s track with left-sided direction of deviation during abduction, and increased masticatory muscle tension, especially in the masseter and temporal muscles. The intra-oral study re­vealed upper dental arches with standard overlapping and without dysregulation in teeth positioning. On ra­diographs showing the temporomandibular functional joints according to Schüller subluxation of the left con­dylar appendix was identified (Fig. 5).

Figure 5. X-ray images of the temporomandibular joints. Patient’s mouth is open (according to Schüller)

The functional study, using the Zebris JMA axiograph de­vice, exhibited increased motion range of both condy­lars – 20.6 and 20.2 mm right-left (Fig. 6A), increased size of opened mouth – 48.8 mm, and bilateral restraint of lateral movement: 4.1 mm right-sided and 4.9 mm left-sided (Fig. 6B).

Figure 6. Graphic recording (Zebris JMA) of patient’s condylar movement: A – motion range of condylar appendixes in the joints. B – opening and lateral movement range

Symmetric range of condylar appendixes’ motion con­nected with axiographs (Fig. 7) indicated more the ex­cessive mobility of both jaw heads rather than for one-sided subluxation.

Figure 7. Graphic recording of condylar appendixes motion connected with axiographs indicated more the excessive mobility of both jaw heads’ movement using the Zebris JMA device

The patient was instructed how to accomplish a set of exercises: limiting the size of the aperture – opening the mouth with handling the tip of the tongue to the palate surface and training correcting the jaw’s movable model – opening along the straight line, in front of the mirror. As prescribed, the activity had to be performed 2-3 times a day in batches of 15 to 20 repetitions.

Required physical therapy resulted in marked improve­ment of the masticatory system’s functional position and the patient’s well-being. Follow-up tests performed after 2 months, using the Zebris JMA apparatus, reg­istered significant reduction in the range of opening motion and a slight increase in the range of laterotru­sive motion: right-sided to 6 mm, left-sided to 5.8 mm (Fig. 8A). The size of mouth orifice opening was by 41.8 mm longer, which is about 7 mm less. There was also a shorter length of the articular way of both condylar processes, which due to exercises was reduced by about 3 mm (Fig. 8B).

Figure 8. Graphic recording (Zebris JMA) of the patient’s condyle of mandibular movement and incisal point, after 8 weeks of training: A – opening and lateral movements’ range; B – motion range of both condylar heads in the joints

Case III

Patient R.B., aged 19, presented to the Department of Dental Prosthetics, Pomeranian Medical University, for treatment. The patient received a referral from the Faciomaxillary Surgery Clinic, where he was due to extensive skull facial bone injury, after falling from a great height.

The radiological documentation (description of an X-ray) performed immediately after the injury showed:”Photos of part of the facial skull, made by means of multislice computed tomography with three-dimensional image reconstruction, show fragmenta­tion of the mandibular head on the left side with dis­placement of bone chips to the medial side and to the front” (Fig. 9 A and B).

Figure 9. Photos of the facial skull – the technique of multislice computed tomography

The direct cause of the patient’s request for help was pain coming from the teeth, a significant re­duction in dilation of jaws and associated with the above symptoms difficulties in eating. Clinical ex­amination revealed the size of the opening slot – 10 mm and broken tooth crowns: 46, 47 (class III ac­cording to Elis) and broken teeth 24 and 31 (class IV-V according to Elis) with significant exposure of the pulp chamber. The pantomography picture con­firmed fracture with displacement and fragmenta­tion of the mandibular head on the left and fracture without displacement of the mandibular body, pass­ing through tooth socket 48.

The patient underwent conservative treatment, consist­ing of applying contemporary wound dressing of damaged teeth and devitalization of teeth with bare dental pulp. Due to the limited aperture of 10 mm, in the first months after the injury, no additional functional studies were per­formed. Physical rehabilitation was implemented, involv­ing exercises to increase the range of mandibular motion. After several weeks of rehabilitation, further conservative treatment was performed and also a functional examina­tion was carried out with a Zebris JMA device.

The results of the functional examination: Record of abduction movement shows a strong devia­tion of the mandible to the left: 10 mm from the midline (Fig. 10).

Figure 10. Graphic record of abduction and adduction movements in the frontal plane, scope of the left-sided deviation in the maximum opening – 10 mm

Significant deprivation of motion in the left (damaged) temporomandibular joint and a small range of motion of the left condylar appendix -5.3 mm. The device also re­corded the retrusive motion, minor-normal on the side of the healthy joint and paradoxically large (nonphysiologi­cal) distal range of motion on the diseased side – 4.9 mm (Fig. 11A).

Figure 11. Graphic recording (Zebris JMA) of movement of mandibular heads and incisal point, after 3 months of muscle training: A – range of motion of both heads of the condylar process in the joints; B – ranges of opening side movements

Impairment of right-sided activity – 3.7 and normal mo­tion range to the left. Despite disturbances in the func­tioning of registered damaged alveolar condyloid the observed range of opening movement was correct and located within the normal scope. The size of opening ap­erture captured on the receiver was 41.3 mm (Fig. 11B) and was sufficient to effectuate conservative and pros­thetic treatment. The patient was also recommended to perform further muscle exercises designed to re­store the correct path of abduction and adduction of the mandible.

Discussion of the results

Restoring proper relations between the mandible and the jaw, in the group of patients with temporomandibular joint dysfunctions, is the overriding need [15,27]. The li­mitation of mandibular activity is often the consequence of damage to cartilage-bone and/or ligament elements of temporomandibular joints suffering after trauma.

The factors that generate disturbances within the stoma­tognathic system are among others injuries within the facial part of the skull, including fracture of the condylar process. These represent 12% to 29% of all fractures of the mandible [1,26]. Mostly they are the result of lesions around the chin. In the treatment of bone fractures the main principle is to manipulate bone chips and set them as close as possible to the anatomical position. There­fore the orthopaedic surgical method appears to be the most appropriate. However, anxiety about postoperative complications, reaching 20% of cases [23,26], encourages managing this type of injury with conservative-orthopa­edic intervention. However, the most dreaded menace – permanent mimetic paralysis – occurs, according to some authors (Cieślik) relatively rarely (0.9%) [5]. The fear of complications involving anatomical difficulties – the location and structure of temporomandibular joints – causes that the prevalent modality is still a non-opera­tive procedure. This involves the repositioning of bone chips by the skin layers, immobilising them with splints [25,26] and adopting a maxillo-mandibular resort flexi­ble traction for 2-6 weeks. The next phase of treatment is the use of mechanotherapy in order to avoid dysregu­lation in mobility of the temporomandibular joint. The percentage of patients with a positive, satisfactory result of this treatment is comparable to the outcomes achieved applying the orthopaedic surgical process and is about 50% according to Arkuszewski and Hilt [1].

In discussed case number III only the second stage of this treatment was adopted. Trauma caused by the pa­tient’s bad condition did not allow surgical intervention to be performed. The implementation of bite splint and application of traction were also omitted. The main ac­tion was muscle therapy, which aimed to restore the maximum possible efficiency of the masticatory loco­motor system.

Additional studies, using computer supported instrumen­tal techniques, have been highly useful in the course of the described matter.

Similar to the feedback of Panek, it should be established that an easy to use, lightweight measuring system that is harmless for the patient during the test, such as the Zebris JMA system, can be widely used in clinical diag­nosis [19].

In evaluation of the quality of abduction and adduction movements, not only the observation of the incisal point in the clinical trial is helpful, but also the analysis of gra­phs, showing the simultaneous movement of both con­dylar processes and their interdependence, as well as observational study of all joint elements’ activities in expanse and time. This type of record makes it possible to assess the quality of deviation in a particular move­ment. It also indicates the joint responsible for the di­sorder. In this concrete episode, accurate analysis of movement recordings, performed by the damaged man­dibular head, allowed exclusion of serious complication occurring in this type of injury, treated mainly surgical­ly – joint ankylosis [1]. Based on the obtained graphs, it can be concluded that, although the anterior movement of left condylar process was blocked, the compensatory mechanisms enabled a quite significant range of abduc­tion motion. The graphic record shows that this was po­ssible by dint of a slight posterior condyle movement during the described activity.

In the search for reasons for continuing, non-traumatic mobility restriction, we cannot forget inflammatory myopathies and the patient’s unwillingness caused by fear of deterioration. In cases of painful and painless myoarthropathy, coexisting cracks in the temporoman­dibular joints lead to functional limitation of jaw move­ments [22,27]. In many cases, patients suffer increased levels of depression, although the results of electro­myographic tests do not always indicate the coexis­tence of neurogenic changes in the form of increased tension within the masticatory muscles. According to Dubojska, secondary depression, which might be a sign of lack of acceptance in relation to stressful fac­tors (pain, dysregulation), is an emotional dysfunction, which in certain conditions and among susceptible in­dividuals may cause or exacerbate dysfunctional symp­toms [6]. Maintaining this condition – the reduction of muscles’ functioning – can lead to muscle shortening and atrophy. The level of masticatory muscles’ activ­ity plays a significant role in proper functioning of the masticatory motor system. The graphic records analy­sis of loose and articulation mandible movements and comparing the electromyographic records before and after the treatment is an important addition to evaluat­ing the treatment effectiveness of temporomandibular movement disorders.

The undeniable advantages of the Zebris JMA device, used for testing, are the educational aspects. It is much easier to motivate the patient to perform intensive exercises if he can watch the treatment progress on a computer screen. The graphic image of condylar processes’ kinet­ics obtained by the appliance, in combination with the results of radiological examination, showing the absence of jaw obstacles that could reduce condylar activity in the joints, demonstrates the muscle or psychological aetiol­ogy of disorders. Not always and not every impairment of masticatory apparatus movement requires complicated splint or pharmacotherapy [13,15,20].

Therapy using muscle training generally is considered as a conservative method of treatment. Stretching, iso­metric and relaxation exercises are relatively simple and non-invasive, and therefore can be successfully rec­ommended to most of the patients. Muscle exercise rou­tines lead to shortening excessively expanded muscle fibres, while restoring the full length of shortened ones; they also restore the symmetry and the correct ten­sion. The performed evaluation proves that we have to agree with the opinion of Drobka and Karasiński, who in their research, using the above-mentioned therapy, ob­tained 70% efficacy in the area of mandibular hyper­mobility treatment [7]. However, it must be remem­bered that the recommendation of this solution should be preceded by appropriate diagnostic procedures, com­pleted with the correct functional diagnosis. The exer­cises should be carried out moderately, with graduated intensity, in order to avoid aches, which might discour­age patients from undertaking the suggested manner of treatment. Kinesis therapy effectiveness largely de­pends on the scrupulousness of the patient. In all three discussed cases a satisfactory medicinal ef­fect was achieved. Nonetheless, the patients were in­formed about the need for constant control of the masti­catory functional condition and about the eventuality of further healing.

Conclusions

1.Muscle training is crucial in restoring the mobili­ty of the mandible, in a range as close as possible to nor­mal, even after extensive trauma of the TMJ.

2.Analysis of the mandibular activity graphic recordings showed that even substantial limitation of one mandibu­lar head’s movement, such as head damage, does not sig nificantly affect the range of abduction motion.

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The authors have no potential conflicts of interest to declare.

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