The role of occlusal splints (soft and hard) in the management of Myofascial Pain Dysfunction Syndrome

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1 The role of occlusal splints (soft and hard) in the management of Myofascial Pain Dysfunction Syndrome Hajer Ibrahem Abdulla B.D.S, M.Sc. (1) Sabah Moshi Saka B.D.S., M.Sc., PhD. (2) Ali Abd Al-Hur Al-Ibrahemy B.D.S. (3) ABSTRACT Background: The term temporomandibular disorders (TMDs) are a collective term embracing a number of clinical problems that involve the masticatory muscles, the temporomandibular joints (TMJ) and associated structures, or both. The TMDs can be broadly divided into masticatory muscle disorders (TMJ dysfunction syndrome) and TMJ disorders. Dysfunction of the masticatory muscles or myofascial pain dysfunction syndrome (MPDS) is relatively common. The occlusal interferences theory and psychophysiological theory are the major causes of MPDS. The soft and hard occlusal splints (OSs) used in the management of MPDS had been controversial. The aim of study was to test the role of OSs as a treatment modality for myofascial pain dysfunction syndrome of TMJ caused by spasm of masseter and temporalis muscles by the use of surface electromyography (EMG) and Helkimo index criteria, and to compare between the efficacy of soft and hard occlusal splints in the management of myofascial pain dysfunction syndrome. Patients and methods: This study was carried out through clinical examinations for a sample of sixty patients with MPDS, by use of Helkimo index criteria. The ages ranged from 20 to 53 years, the gender distributed as 20 males and 40 females. The patients divided into group A and group B, subjected to soft OS and hard OS respectively. Each patient subjected to three visits of measurements by EMG for superficial masseter and temporalis muscles and Helkimo index criteria records. The primary visit was for diagnosis and impression taking, then the first visit called pretreatment visit, then two weeks, and four weeks after insertion of OS. Results and discussion of this study showed that the clinical dysfunction index (type 2 Helkimo index) which was more reliable index in the assessment of TMJ dysfunction syndrome that related to masticatory muscles, since 1974 to nowadays. This study gave this index its reliability and accuracy by approximately coincidence between the EMG and Helkimo index results, this fact encourage by the reliability of the use of EMG in the researches of TMDs and MPDS. This study also showed that the records of Helkimo index criteria for patients managed with soft OS had more significant differences from patients managed with hard OS in the second visit after treatment, while the differences were not significant in the third visit after treatment. The results of EMG measurements of masseter muscle are of highly significant differences in soft OS group compared with the hard OS group in third visit after treatment, but no significant differences in the second visit after treatment. The results of EMG records for temporalis muscle were highly significant differences in the soft OS group comparing with hard OS group in the third visit after treatment, but it was significant in the second visit after treatment. Conclusion: The OS play a major role in the management of MPDS by reducing the symptoms associated with this syndrome which are pain, muscle spasm, TMJ sounds, and limitation of mandibular movements in different degrees. The use of soft OS was more effective than hard OS in the management of MPDS. Key words: MPDS - Soft and Hard OSs - Surface EMG - Helkimo index - Masseter muscle - Temporalis muscle Parafunctions Malocclusion. (J Bagh Coll Dentistry 2011;23(61-69). INTRODUCTION This study focuses on the management of dysfunction of the masticatory system. The masticatory apparatus is a specialized unit that performs multiple functions, including those of sucking, speaking, cutting and grinding food, and swallowing. The loss of these functions in association with pain is characteristic of masticatory system disorders and causes significant distress that can be severely disabling. In the past, disorders of the masticatory system were generally treated as one condition or syndrome, with no attempt to differentiate subtypes of muscle or joint disorders. (1) Professor of oral medicine Al-Mustansiriya University college of dentistry (2) Professor of oral pathology Al-Mustansiriya University college of dentistry (3) Dentist in Babylon University college of dentistry The term temporomandibular disorders (TMDs) is a collective term embracing a numbers of clinical problems that involve the masticatory muscles, the temporomandibular joints (TMJs) and associated structures, or both 1. The TMDs can be broadly separated into masticatory muscle disorders or TMJ dysfunction syndrome and TMJ disorders 2,3,4. The MPDS has a variety of names, including pain/dysfunction syndrome, facial arthromylgia, and craniomandibular dysfunction 5. The diagnostic difficulties of the TMDs that arise are most often related to the similarity in signs and symptoms produced by MPDS, degenerative joint disease, and internal derangements of the TMJ 6. Dysfunction of the masticatory muscles or MPDS is relatively common 7. In case of MPDS the altered muscle movement, sometimes restricted and sometimes involving deviation of Oral Diagnosis 61

2 the midline of the chin on mouth opening. In this movement alteration, jaw muscles are behaving abnormally, indeed, they are the primary site of pathology 8. Various types of oral occlusal splints (OSs) have been used for over half a century to treat TMDs, but there has been considerable debate about how OSs should be designed, which material is preferable, how long they should be used, and what they actually do therapeutically. However there is enough information in the scientific literatures at this time to reach some evidence-based conclusions about these issues. The main focus of many studies is on the materials and designs of various OSs in term of their proposed mechanisms of action and their claimed clinical objectives. Based on current scientific evidence, an analysis is presented regarding the role that OSs can or cannot play in the management of TMDs. The actions of the OSs may be an effective treatment modality for some TMDs patients, but some studies had been considered that OSs actions was related to their potential for acting as an elaborate placebo rather than any specific therapeutic mechanism 9. In the 21 st century, it is safe to assume that oral physicians are familiar with two terms: OSs and TMDs. However, some clinicians may be surprised to learn that each of these terms has been redefined in light of research findings from the past years. The conceptual basis for designing and using OSs as treatment devices also has changed considerably, ranging from simple jaw relaxation concepts to complex jaw repositioning rationales 9. This study was conducted specifically to focus on the use of soft and hard OSs in the treatment of MPDS resulting in evidence-based conclusions regarding this issue, and describing the differences in materials used in fabrication of OSs. In addition to analyzing and interpretation about the correlation between the muscular spasm and the TMJ dysfunction syndromes. The aim of study was to test the role of OSs as a treatment modality for myofascial pain dysfunction syndrome of TMJ caused by spasm of masseter and temporalis muscles by the use of surface electromyography (EMG) and Helkimo index criteria, and to compare between the efficacy of soft and hard occlusal splints in the management of myofascial pain dysfunction syndrome. PATIENTS AND METHODS Patients' selection A sample of sixty patients, taken from the postgraduate clinic of the oral medicine department in the college of dentistry of Al- Mustansiriya University in Baghdad from January to August 2010, was included in this study. The patients were diagnosed as having myofascial pain dysfunction syndrome. The ages of patients ranged from 20 to 53 years. The gender was 20 males and 40 females. Methods The diagnosis had been done according to symptoms of MPDS that are listed in clinical dysfunction index which is the second type of Helkimo index 7. The diagnosis had been done by using Helkimo index 7 criteria to separate the included patients from the excluded patients. These criteria were:- range of the mandibular motion (degree of mouth opening), TMJ function impairment, muscle tenderness during palpation, TMJ pain during palpation, and pain during mandibular movements. The patients ranged from mild, moderate and severe dysfunction. By the clinical dysfunction index criteria, the patients with inflammatory, traumatic, and infectious diseases of the TMJ and related musculature like rheumatoid arthritis, osteoarthritis, and myositis were excluded from this study. This is a comparative study in which patients are randomly divided into two groups of 30 patients. Group A had been managed by soft occlusal splint (Fig. 1), and group B had been managed by hard occlusal splint (Fig. 2) at same instructions, motivations, and period of wearing and records of follow up visits. The primary visit achieved by clinical examination and impression taking, then the casts poured and transferred to special dental laboratory to do the OSs by Biostar device. In the first visit or pretreatment visit, each patient received OS, Helkimo index criteria and electromyographic (EMG) records for superficial masseter muscle and anterior portion of temporalis muscle at both sides with instructions to wear full coverage OSs during sleeping at night only, then the same records will be done in the second visit after two weeks and after four weeks of treatment. The interexaminer calibrations were performed with the supervisor for 10 patients to make the records more reliable in the further readings of this study. Operational procedures of Metron Clinical EMG Step 1: Connection to mains, the mains power cord should be connected to the Metron EMG (Fig. 3) IEC, power socket at the rear of the Metron EMG. The other end of the power cord should then be plugged into the mains power outlet, and the power outlet switched on. The Charging indicator in the battery window after a Oral Diagnosis 62

3 few seconds should be illuminated green, indicating the power is connected correctly. Step 2: Battery charging, the Metron EMG runs via an internal rechargeable battery. This battery is charged by an internal charger that is powered by the mains. When the Metron EMG is not in use and is off, the internal battery is recharging, this is indicated by the green LED (Light Emitting Diode) in the battery window above the label charging. When the EMG is on the charging indicator goes off and the battery charge level is displayed on a small bargraph above the label level. Before using for the first time ensure the battery is completely charged, switch the EMG on by pressing the power button and check the battery level bargraph, if the bargraph has less than 5 bars illuminated, let the EMG charge overnight to full capacity. it is important to keep the EMG connected to the mains to maintain battery charge level and battery longevity. Step 3: Leads putting, the EMG has three sockets at the front of the unit. The sockets are labeled channel A, channel B and reference electrode. Both the A & B channels are 5 pin sockets that connect to the patient electrode leads. The reference electrode is a single banana socket that connects to the reference lead. At the patient end of the leads all the leads have 2.5 mm plugs that plug into the electrode pigtails. When using both channels or a signal channel the reference electrode must be connected to the patient to ensure a reliable EMG signal. Step 4: Checking unit, before using the Clinical EMG on a patient for the first time, it is advisable to confirm the Clinical EMG is operating normally. The following checklist can be followed to confirm the correct operation of the displays and controls (once the unit has been charged). Press power, unit will power up, illuminating all the displays. Check battery level bargraph, ensure more than three bars are illuminated. Step 5: Rotate threshold A dial clockwise until all of the channel A bargraph is illuminated (ensure there are no missing segments) then rotate threshold A dial anti-clockwise until all of the channel A bargraph is dark. Step 6: Rotate threshold B dial clockwise until all of the channel B bargraph is illuminated (ensure there are no missing segments) then rotate threshold B dial anti-clockwise until all of the channel B bargraph is dark. Step 7: To adjust the EMG threshold simply adjust the threshold A or threshold B dials to the appropriate level. By turning the threshold dial clockwise the bargraph level is moved upwards and by turning the dial anti-clockwise the bargraph is moved down. The threshold therefore can be used to reduce the muscular effort required to get into the amber region of the bargraph or increase the muscular effort required to get into the amber region. By adjusting the range and threshold the EMG bargraphs can display EMG in a convenient format for the patient. The real time numeric values of EMG are not affected by the range and threshold settings as the real time numeric values are the measured values of EMG. Step 8: Press the ( > ) selection button several times and ensure the setup indicators illuminate in a sequence to the right, press the ( < ) selection button several times and ensure the setup indicators illuminate in a sequence to the left. Press the ( > ) selection button several times until the status indicator is illuminated on the setup window. Rotating the adjust dial slowly clockwise, should illuminate in sequence the statistics indicators in a rightward direction, rotating the adjust dial counter-clockwise should illuminate in sequence the statistics indicators in a leftward direction. Step 9: Using the selection buttons and the adjust dial, enter the following parameters in the setup window. Trials = 10, Rise = 10, Hold = 10, Fall= 10 and Relax = 10. Press the treatment button (two beeps), in the template window the trials should indicate 10, after a small delay the unit will beep again, the work/rest bargraph should slowly illuminate the segments until the bargraph shows 13 green segments, 4 amber segments, and 2 red segments, after 3 seconds the unit will beep in a low tone and the bargraph will then slowly turn off the segments one by one until one green segment remains on. The unit will beep, and the trials in the template window will show 00. Step 10: It is advisable for the practitioner to familiarize themselves with the operation of the Clinical EMG by testing the QB170 on themselves to gain a feel for the effect of the controls, and in particular the range and threshold. Step 11: The patient set on dental chair at upright position, and manipulated the mandible at rest position, and ask the patient do not speak, laugh, and close or open his/her mouth until the measurements of device were stopped. Step 12: The reference electrode placed on the any site in the body (in this study this electrode placed on the dorsal surface of the left hand), then the channel A is placed on the left superficial masseter muscle and channel B on the right channel or vice versa. Each channel (A or B) contain two pieces surface electrodes, the Oral Diagnosis 63

4 black electrode (active electrode) and red electrode (reference electrode), figures (4,5). Step 13: Before applying the electrodes on muscle, the skin over the muscle must be clean and dry, then a special gel applied over the skin of muscle, then the active electrode (black electrode) over the body of the muscle and the reference electrode (red electrode) over the insertion part of the muscle. Step 14: The dual channels A and B applied on the right and left superficial masseter muscles by placed the red electrode beneath the zygomatic arch at the oblique direction toward the angle of the mandible, and placed the other electrode over the angle of mandible at same direction of the first electrode(fig. 4). Then after the first measurement finished, the electrodes placed over the anterior part of the temporalis muscles. The red electrode placed over the zygomatic arch behind the eye and the black electrode placed above it in direction toward the temporal bone(fig. 5). RESULTS The distribution of patients according to the gender of group A was 26 females (86.7%) and 4 males (13.3%) (Fig. 6), the ages range was from 20 to 53 years, sorted in four groups, years (73.3%), years (3.3%), years (16.7%), and over 50 years old (6.7%), these findings are demonstrated in (Fig. 7). The distribution of patients according to the gender of group B was 14 females (46.7%) and 16 males (53.3%) (Fig. 6), the ages range was from 22 to 50 years, sorted in four groups, years (30.1%), years (33.3%), years (33.3%), and over 50 years old (3.3%), these findings are demonstrated in (Fig. 7). The Helkimo Index Criteria Records The T-test of the Helkimo index records between group A and group B in each visit was shown in table (1), for first visit there was significant differences between two groups (2.511) P-value=0.015, and there was significant differences between two groups in the second visit (0.415) P-value=0.048, while there was no significant differences in the third visit (0.601) P- value=0.089, after treatment with OSs. The EMG Records of Masseter Muscle The T-test of the standard deviation of rest between group A and group B in the first visit showed no significance (0.467) P-value=0.642, and showed no significant differences (1.913) P- value=0.061 in the second visit, while the results in the third visit were highly significant differences (2.937) P-value=0.005 as shown in the table (2). The T-test of the average of rest between group A and group B in the first visit showed no significant differences (0.647) P- value=0.520, and showed no significant differences (1.090) P-value=0.280 in the second visit, while the result in the third visit showed significant differences (2.192) P-value=0.032, as shown in table (2). The EMG Records of Temporalis Muscle The T-test of the standard deviation of rest between group A and group B in the first visit showed no significant differences (0.087) P- value=0.931, and showed no significant differences (1.862) P-value=0.068 in the second visit, while the results in the third visit were highly significant differences (3.349) P- value=0.001, these results were shown in the table (3). The T-test of the average of rest between group A and group B in the first visit showed no significant differences (0.114) P- value=0.910, while showed significant differences (2.069) P-value=0.043 in the second visit, but the result in the third visit showed highly significant differences (3.038) P- value=0.004, table (3). DISCUSSION The Age and Gender Incidence in Patients with MPDS showed that the ages from 20 to 29 years old was the main age of the MPDS incidence patients (73.3% in group A and 30.1% in group B), therefore the MPDS is a syndrome of the young 6. This period of young ages affected by stress and other psychological problems, therefore the parafunctional habits appeared like bruxism and clenching, which were the major causes of concern in this study. This study showed that the incidence of the MPDS was larger in females than males due to the females were more prone to do parafunctional habits and more sensitive to any malocclusions or occlusal interferences. In normal subjects without TMD, it has been reported that female subjects generated higher EMG amplitudes during the exercise of lifting the same weight and also displayed significantly and consistently higher fatigue and recovery ratio during experimentally induced loading compared with male subjects 10. The females sample percentage was 66.6 %, and for males was 33.3 % from the sample of 60 patients participated in this experimental study. The comparison between group A patients and group B patients by use of T-test according to Helkimo index records to each visit in this study had shown significant differences (2.511) in the first visit between two groups due to the mean pretreatment scores of the group A (mean Oral Diagnosis 64

5 of scores=13.23) more than the pretreatment scores of group B (mean of scores=9.63). The T- test of the second visit was (0.415) also showed significant differences in the treatment of group A to group B patients, due to the mean of scores of group A (4.3) was less than in group B (4.8). In the third visit of treatment the T-test of group A to group B was not significant (0.601) due to the P-value=0.089 > T-table=0.05. So, the use of soft OS was more significant differences comparing with the use of hard OS in the second visit of treatment (two weeks after treatment), but it was not significant in the third visit of treatment. These findings according to Helkimo index records. Splint therapy is effective at first, but the usual trend with longer treatment is to loose its effects 11. The T-test of standard deviation and average of rest for masseter muscle between group A and group B in the first visit (pretreatment visit) was no significant differences in the EMG value. This means that EMG records of both groups were approximately coinciding, so the variance and bias between two samples disappeared to reduce the errors and gave the accurate results about the use of soft and hard OS. The T-test of standard deviation and average of rest for masseter muscle between two groups also showed no significant differences in the second visit after two weeks of treatment due to both OSs play a role in reducing the myospasm of masseter muscle after two weeks of treatment, so there was no statistically significant differences in their usage to reduce the myospasm of masseter muscle. But after four weeks of treatment, the T-test of standard deviation of rest between these groups was highly significant differences of treatment and the T-test of the average of rest showed significant differences as the hard OS was effective at first, but the usual trend with longer treatment is to lose its effects 11. This study agrees the Rugh et al. study in that the soft OS was still working to lower the resting potential values of EMG records for masseter muscle, and the soft OS is better than the hard OS in reducing myospasm of masseter muscle, especially in prolonged treatment time than short treatment time, but the hard OS worked at short treatment time as shown in the second visit after treatment, then the curve of treatment will drop in the prolonged time (four weeks after treatment). The T-test of standard deviation and average of rest for temporalis muscle between group A and group B in the first visit (pretreatment visit) was no significant differences in the EMG value. This mean that EMG records of both groups were approximately coinciding, so the variance and bias between two samples disappeared to reduce the errors and gave the accurate results about the use of soft and hard OS. The T-test of standard deviation for temporalis muscle between two groups also no significant differences in the second visit after two weeks of treatment due to both OSs play a role in the reducing the myospasm of temporalis muscle after two weeks of treatment, so there was no statistically differences in their usage to reduce the myospasm of temporalis muscle. But after four weeks of treatment, the T-test of standard deviation and average of rest between these groups was highly significant differences of treatment due to the temporalis muscle more sensitive to the use of OS and due to its position far away from the oral cavity, and the masseter muscle had more powerful action during bruxsim and clenching parafunctions, so the spasm in the masseter muscle more than the spasm in temporalis muscle. This study showed that the clinical dysfunction index (type 2 Helkimo index) which was more reliable index in the assessment of TMJ dysfunction syndrome that related to masticatory muscles, since 1974 till nowadays, This study gave this index its reliability and accuracy by approximately coincidence between the EMG and Helkimo index results, this fact encouraged by the reliability of the use of EMG in the researches of TMDs and MPDS 6,7. The use of occlusal splints for sleep bruxism and clenching, with electromyographic records associated to Helkimo index evaluation had been conducted by Leonardo 12 that aimed to evaluate long-term effects of using an occlusal splints in patients with sleep bruxism and clenching, using surface electromyography (EMG) of superficial masseter and anterior part of temporalis muscles, as well as the Helkimo Index 7. The subjects were 15 individuals aged from 19 to 29 years, complaint from sleep bruxism and clenching, with presence of signs and symptoms of temporomandibular disorders (TMDs), which never have used occlusal splints. The subjects answered the Helkimo s Index and underwent EMG before and after 60 days of occlusal splints use. There was no indication of a significant decrease in mean EMG levels over the therapy in the muscles, A significant decrease in TMD signs and symptoms according Helkimo index records were observed in patients after 60 days of occlusal splints therapy 12, while this study showed highly significant in average and standerd deviation of EMG levels to both masseter and temporalis muscles of both groups after 4 weeks of treatment and highly significant Oral Diagnosis 65

6 decreased in the signs and symptoms according Helkimo index records. The differences between this study and Leonardo study were: the Leonardo was use hard OS to 15 patients aged from years for long period of treatment (60 days), while this study used soft and hard OS for 60 patients aged from years for 4 weeks. Another study to compare between flexible and hard stabilization splints in the treatment of TMDs was conducted by Al-Ani et al. 13, forty patients (30 female and 10 male) with age group years old were randomly selected. The parameter was the case history, signs and symptoms. The patients wore the stabilization splints for one month and three month respectively. The outcome of this study was the patients treated with soft appliance for longer period of time show improved treatment and more relived and willing to continue the treatment than those treated by hard splints. The similarity between the kais study and this study was the soft OS more beneficial in the management of TMDs, the ratio of females was more the males, and the patients worn the splints at night only, but the differences were the long term period of treatment, absence of the specific parameters, such as EMG, Helkimo index, and research diagnostic criteria (RDC) for TMDs, the ages of patients in this study were years while the ages of patients were years in the Kais study, and he try to treat the TMDs as a whole case, but this study try to manage the MPDS as a specific case to give more specific information and details about the one case from general TMJ diseases or syndromes. This study showed that most of the patients in group A (soft OS wearer) were well tolerated their appliances and had very good accommodation, and with minimal adverse effects, than the patients in group B (hard OS) that need multiple visits for finishing and adjustment for reached to acceptable fitness and comfortability of wearing the hard OS. The adverse effect of soft OS was dry mouth only that managed by multiple water mouth rinses. While the adverse effects of hard OS was pain in the teeth due to the rigidity of this appliance in addition to dry mouth. Some of patients has showed non significant results in the treatment, which represented by four patients in group A, and four patients in group B. These 8 patients represented by 6 females and 2 males, these results occurred because the females were more sensitive to stress, and difficulties in tolerating their OSs. But, the other 2 males due to the intermittent wearing of OS and the heavy stress on them 14. Yet the occlusal splints "does not actually prevent or cure the bruxism and clenching, but it will prevent damage to the TMJ, masticatory muscles, and teeth when the parafunctions occurs" 15. According to Rugh et al. 11, splint therapy is effective at first, but "the usual trend with longer treatment is to lose its effects. In other words, one usually sees a dramatic decrease or increase in EMG activity the first few nights of splint usage, followed by a gradual return to pretreatment EMG values." The limited effectiveness of the traditional splint is also "borne out by the common clinical finding that patients may bite large teeth marks into night bite guards and frequently fracture appliances" 15. REFERENCES 1- Greenberg, Glick, Ship. Burket s Oral Medicine, Bruce. DMD: The temporomandibular disorders. 11 th Ed. p. 224; Griffiths RH. Report of the president s conference on the examination, diagnosis, and management of temporomandibular disorders. J Am Dent Assoc 1983; 106: Eversole LR, Mahade L. Temporomandibular joint internal derangements and associated neuromuscular disorders. J Am Dent Assoc 1985; 110: Clark GT, Seligman DA, Solberg WK, Pullinger AG. Guidelines for the examination and diagnosis of temporomandibular disorders. J Craniomand Disord 1989; 3: Rothwell PS. The terminology of the masticatory apparatus problems. Br Dent J 1980; 66: Laskin MS. The temporomandibular disorders: diagnosis and etiology. In: Sarnat BG, Laskin DM, editors. The temporomandibular joint: a biologic basis for clinical practice. 4 th ed. Philadelphia: Saunders; p , Helkimo E. Studies on the function and dysfunction of the masticatory system. III. Analyses of anamnesis and clinical recording of dysfunction with the aid of indices. Swedish Dent J 1974; 67: Schwartz L. Conclusions of the temporomandibular joint clinic at Columbia. J Periodontal 1958; 29: Klasser and Greene: oral appliance in the management of temporomandibular disorder. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009; 107: Klasser and Okeson: The clinical usefulness of surface electromyography in the diagnosis and treatment of temporomandibular disorders. Chicago, JADA Continuing Education. From Internet, Rugh JD, Graham GS, Smith JC, Ohrbach RK. Effects of canine versus molar occlusal splint guidance on nocturnal bruxism and craniomandibular symptomatology. J of Craniomandibular Disorders 1989; 3: Leonardo LM. Occlusal splint for sleep bruxism: an electromyographic associated to Helkimo Index evaluation. J of Primary Care Sleep Medicine 2004; 8: Oral Diagnosis 66

7 13- Al-Ani Z, Gray R, Davies S, Solan P, Glenny A. Stabilization splint therapy for the treatment of temporomandibular myofascial. A systemic review. J Dent Edu 2005; 69: Hartmann E. Bruxism. In MH Kryger T Roth & WC. Dement (Eds.). Principles and Practice of Sleep Medicine (2 nd ed ). Philadel: WB Saunders Trenouth MJ. The relationship between bruxism and temporomandibular joint dysfunction as shown by computer analysis of nocturnal tooth contact patterns. J of Oral Rehab 1979; 6:81 7. Figure 1: The Soft Occlusal Splint Figure 2: The Hard Occlusal Splint Figure 3: Metron Clinical EMG with Dual Surface Electrodes Figure 4: The Position of the Black and Red Surface Electrodes over the Skin of Superficial Masseter Muscle Oral Diagnosis 67

8 Figure 5: The Position of the Black and Red Surface Electrodes over the Skin of Temporalis Muscle Figure 6: Samples Distribution by Gender Figure 7: Samples Distribution by Age Table 1: The T-test between group A & group B for Helkimo Index Mean S.D T-test P-value Sig. Helkimo index Group A (before treatment) Group B S Helkimo index Group A (after 2W) Group B S Helkimo index Group A N.S (after 4W) Group B S: Significant at level P-value < N.S: Non significant at level P-value > Oral Diagnosis 68

9 Table 2: The T-test between group A & group B for EMG records of masseter muscle Mean S.D T-test P-value Sig. EMG Masseter Group A N.S muscle (before treatment) Group B EMG Masseter Group A sd r N.S muscle (after 2W) Group B EMG Masseter Group A H.S muscle (after 4W) Group B EMG Masseter Group A N.S muscle (before treatment) Group B EMG Masseter Group A avg r N.S muscle (after 2W) Group B EMG Masseter Group A S muscle (after 4W) Group B H.S: Highly significant at level P-value < 0.01 S: Significant at level P-value < N.S: Non significant at level P-value > Not: The mean and standard deviation of EMG records in microvolts. Table 3: The T-test between group A & group B for EMG records of temporalis muscle Mean S.D T-test P-value Sig. EMG Temporalis Group A muscle (before treatment) Group B N.S sd r EMG Temporalis Group A muscle (after 2W) Group B N.S EMG Temporalis Group A muscle (after 4W) Group B H.S EMG Temporalis Group A muscle (before treatment) Group B N.S avg r EMG Temporalis Group A muscle (after 2W) Group B S EMG Temporalis Group A muscle H.S Group B (after 4W) Not: The mean and standard deviation of EMG records in microvolts. Oral Diagnosis 69