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There are many methods of fabricating an occlusal splint. The advantages of the technique described are as follows: (1) little intraoral adjustment is required, (2) there is ease in construction, and (3) only one set of diagnostic casts can serve for both occlusal analysis and splint construction. The disadvantage is that an occlusion with group function cannot be produced by this method.
Five fabrication techniques and two storage methods were used to construct and store specimens to investigate the dimensional stability of acrylic resin occlusal splints. A research model was developed to more closely approximate the tooth coverage limits of occlusal splints. Ten specimens were fabricated on individual stone casts for each of the five techniques. Four die pins were transferred to each specimen, and the distances between the inside diameters of the pins were measured over a 2-week period. After construction, initial measurement, and removal from the cast, each acrylic resin specimen was stored in either a wet or a dry environment. Measurements between pins were made and recorded at five time intervals. The sprinkle-on techniques resulted in less dimensional change than the dough application, the vacuum-adapted resin sheet and dough application, and the heat-cured denture processing techniques. Acrylic resin specimens stored in a wet environment showed less distortion 2 weeks after fabrication.
The effect of canine guidance of a full-arch maxillary flat occlusal splint on the level of activation of the anterior and posterior, temporal, masseter and suprahyoid muscles during maximal clenching, were studied in 14 subjects without craniomandibular disorders. The results revealed that, the level of electromyographic activity of anterior and posterior temporal and suprahyoid muscles during maximal clenching on the occlusal splint in habitual closure was unchanged, as compared to biting in the intercuspal position (ICP), while the activity in the masseter muscle, on average, was increased slightly (13 percent). In contrast, the level of activation of the jaw elevator muscles decreased significantly during maximal clenching on the cuspid ramp of the splint, as compared to the biting in ICP or clenching on the splint. However, the degree of reduction of activity was not symmetrical, and was most pronounced in the masseter muscle of the biting side and in the anterior and posterior temporal muscles of the non-biting side. No significant difference was observed in the activity of the suprahyoid muscles.
Electromyograms (EMGs) of the temporal and masseter muscles in sixty patients with temporomandibular joint disturbance syndrome (TMJDS) and thirty controls were recorded and integrated on-line in the postural position and during maximum clenching, before and after occlusal splint therapy. Contrasting with the controls, the myoelectrical activity of the patients was higher in the postural position and lower during maximum clenching, whilst the former in percentage terms increased when compared to the latter. After treatment, the EMG indexes in some patients returned partially, and in others completely, to a normal level. Tenderness in the mandibular elevators, deviated opening and organic change in the TMJ increased the postural myoelectrical activity, in percentage terms, against that of maximum clenching. The myoelectrical activity of the mandibular elevators in the postural position and during maximum clenching was smaller in patients with the occlusal splint than in those without. The results show that the mandibular elevators in the patients with TMJDS were hyperactive and tense, and that the occlusal splint was useful for treating such dysfunction.
In a double blind study twelve class I probands received occlusal splints with six different customized anterior guidances. The subjective feelings were rated using a psychologic scale. It was shown, that splints with a large "a" were better rated than splints with a small "a". "a" is the radius of the maximal curvature of the sagittal anterior tooth curvature. The transition between positive and negative ratings was very sharp and localized at the individual "a". These results suggest that occlusal splints can be optimized by including customized anterior guidances. A detailed technical description of the manufacturing of these splints is given.
The long-term effects were studied of a full arch maxillary plane occlusal splint on chronic signs and symptoms of craniomandibular disorders (CMD) in 31 patients with nocturnal bruxism. The results revealed that the score and intensity of signs and symptoms in this type of patient fluctuate from day to day and even within a single day. In spite of continuation of nocturnal bruxism, the symptoms of CMD were cured or improved with the long-term use of the occlusal splint. However, in general, the symptoms recurred after discontinuation of splint therapy. The therapeutic mechanisms of the splint during sleep are discussed.
To clarify the short-term effectiveness of stabilization-type occlusal splint therapy, a specific symptom approach was used toward 30 temporomandibular joint dysfunction patients with more than two major symptoms (temporomandibular joint and/or masticatory muscle pain, temporomandibular joint sounds, and limitation of mandibular movement). Eighty-seven percent of the patients with pain responded with this therapy and more than 50% had complete relief of pain 4 weeks after insertion of the splint. Temporomandibular joint sounds and limitation of mandibular movement responded more slowly than pain. These results suggest that the stabilization-type occlusal splint should be selected as a first choice among several therapies and that temporomandibular joint pain is particularly susceptible to this therapy.
Fifty-seven patients suffering from migraine, tension headache or tension vascular headache were prescribed a soft occlusal splint for night-time wear. Dental, psychosocial/psychiatric and neurological data were recorded prior to commencement of therapy and at the conclusion of a 3 month treatment period. A statistically significant number of patients presenting with migraine or tension vascular headache experienced marked improvement or complete relief of headache symptoms, but most patients suffering from tension headache failed to benefit from splint therapy. A majority of patients displaying intercurrent features of craniomandibular dysfunction experienced reduction in these symptoms also. There was a statistically significant association between TMJ improvement and headache type. Prior to treatment, patients who subsequently benefited from splint therapy in terms of headache improvement had experienced significantly fewer headaches than patients who failed to respond, although headache intensity and duration were similar in both groups. It is suggested that headache type and frequency may be prognostic indicators of the likely success of dental splint therapy in treatment of headache. Nevertheless, the use of occlusal splints in the treatment of patients complaining of headache in the absence of evidence of craniomandibular dysfunction should not be embarked upon until medical examination has excluded the possibility of organic neurological disorder.
The concept of using the condylar path as the reference for occlusion is questionable for the patient whose temporomandibular joint has pathological changes because the condylar path of TMD patient deviates greatly. After occlusal splint therapy it is suggested that the patient's occlusion be treated using the Twin-Stage Procedure which does not require measurement of the condylar path. The research findings that occlusion controls the condylar path seems to support the concept that if the dentist creates the occlusion properly, the condylar path may be corrected and thereby minimise the micro-trauma which causes TMD.
Twenty-five patients with symptoms of myofascial pain and abnormal jaw function were treated with use of a full arch maxillary occlusal splint. The level of nocturnal activity of the masseter muscle was monitored as were symptoms before, during, and after occlusal splint therapy. A decreased nocturnal EMG level during treatment was noted for 52% of the patients. A return to pretreatment EMG levels after removal of the splint was noticed in 92% of the patients; in 28% no change was shown and in 20%, an increase was shown in nocturnal EMG levels. The splint was most likely to reduce nocturnal EMG levels in patients with least severe symptoms.
Although adequate relief of excess mechanical loading to the joint has been accepted as one of the important treatment concepts in the orthopaedic field, a treatment method for the temporomandibular joint (TMJ) to relieve excess mechanical loading has not yet been established. This study aimed to clarify the effect of an occlusal splint on the maintenance of the distracted condylar position achieved by vibrating-traction method. Vibrating dynamic traction force was applied for 5 min to the right TMJ using vibrating-traction apparatus. A flat stabilization splint was adjusted to keep the mandibular position and the condylar displacement was evaluated for 6 h after the dynamic traction procedure. Mean vertical displacement of the mandibular right first molar immediately after the vibrating-traction for the six subjects was 156 microm (ranging from 141 to 179 microm). The calculated mean condylar displacement immediately after the traction was 480 mum and could be kept to be 381 mum even after 6 h by wearing the flat stabilization splint. From the results of this study, it was revealed that the mechanically tracted condylar position could be maintained by a flat occlusal splint. It was suggested that the vibrating-traction method followed by the provision of occlusal support might have a possibility to work as a mechanical relieving procedure for the TMJ.
With the mandible at rest, the clinical postural position was measured and electromyographic recordings (in seated and supine position, eyes open and eyes closed, before as well as 15 min after insertion of an occlusal splint) were from the anterior temporal and masseter muscles in thirty-one patients with signs and symptoms of mandibular dysfunction and nocturnal bruxism. The results indicated that when the patients were seated upright, there was a distinct postural activity in the anterior temporal and in some patients also in the masseter muscles. This postural activity decreased significantly with closure of the eyes and in supine position. Fifteen minutes after insertion of an occlusal splint, the postural activity in the temporal muscles decreased in 52%, increased in 22% and remained unchanged in 26% of the patients. Moreover, the postural activity reached its lowest level in supine position. The results indicate that the supine position is the body position to be preferred for centric relation recording as well as for occlusal and splint adjustment.
The purpose of this study was to determine the effect of TMJ dysfunction on the recording of centric relation. Centric relation was recorded using an anterior occlusal stop and by bimanual manipulation. Changes in occlusal contacts were recorded before and after occlusal splint therapy in six subjects with TMJ dysfunction. The pantographic reproducibility index and clinical signs and symptoms were used to determine the presence or absence of dysfunction. Use of the anterior occlusal stop resulted in a more posterior, superior initial tooth contact position when compared with bimanual manipulation. Occlusal contact positions were less consistent in TMJ dysfunction subjects than in control subjects. Initial occlusal contacts changed toward centric relation as the dysfunction disappeared. Final occlusal contact was found on the side where clinical signs and symptoms occurred. The condyle on the affected side appeared to be repositioned posteriorly and superiorly in most instances. Occlusal splint therapy was more effective when the splint was adjusted weekly. This study indicates the need to eliminate TMJ dysfunction before recording centric relation or adjusting the occlusion. Occlusal interferences found with TMJ dysfunction are not the same as occlusal interferences found when TMJ dysfunction is absent. Abnormal features on pantographic tracings may aid in indicating the presence of occlusal interferences. Occlusal adjustment in the presence of TMJ dysfunction would result in erroneous occlusal reduction.
OBJECTIVE: To evaluate the treatment effect of bruxism by using myomonitor and occlusal splint therapy. METHODS: By using EMG, audiocontrolled recorder and myollectronic recording device to record and analyse the muscles functional state before and after treatment. RESULTS: Splint therapy was more effective than the myomonitor did, such as teeth grinding stopped in 12 cases to 1 case, grinding time decreased in 13 cases to 10 cases and no significant effect in 2 cases to 17 cases. SPD and V/T curve slope of muscles decreased. CONCLUSION: This indicates that the functional state of masticatory muscles got improved. Splint therapy is one of the effective treatment method for bruxism.
Many studies have shown that various myosin isoforms are involved in muscle contraction. A search for specific antibodies directed against the myosin heavy chain (MHC) resulted in the identification of at least two main classes, referred to as MHC type I and type II. In this study, immunohistology and gel electrophoresis were used to determine the proportion of MHC isoforms in rat deep masseter muscle at different times after the insertion of an unilateral occlusal splint. An increasing proportion of MHC type I isoforms was found in both deep masseters soon after splinting, and this trend continued until 7 days after splint insertion. The type I fibres were clearly distributed on either side of the central axis of the muscle. At 15 days, a significant decrease in the percentage of the type IIb MHC isoform was observed on the occlusal splint side compared to the contralateral side. After 30 days of unilateral splinting, the proportion of type IIb fibres on the splint side returned to baseline whereas on the contralateral side there was an increase in the proportion of this type. The results suggest an initial adaptation after the unilateral occlusal disturbance in which muscles of both sides react in the same way; later, the muscles of each side adapt their expression of MHC isoforms according to altered functional demand.
The postural activity of the temporal and masseter muscles in thirty-one patients with signs and symptoms of functional disorders were studied: before, during and after 3-6 months of occlusal splint therapy. The fluctuating signs and symptoms, as well as the postural activity of the temporal and masseter muscles were significantly reduced after treatment. Further, the coefficients of correlation within pairs of postural activity of the right and left muscles increased significantly. After cessation of the splint therapy the signs and symptoms recurred to the pre-treatment level within 1-4 weeks in about 80% of the patients. The results indicate that an occlusal splint can eliminate or diminish signs and symptoms of functional disorders and re-establish symmetric and reduced postural activity in the temporal and masseter muscles, which can facilitate procedures, such as functional analysis and occlusal adjustment.
To investigate the effects of wearing an occlusal splint on masticatory movements in healthy individuals, twelve healthy individuals were examined. A full maxillary stabilization splint made of heat-cured acrylic resin was fabricated for, and worn by, each individual for 24 hours. Masticatory movement was measured before and after the 24-hour period using a 3-D mandibular movement analyzing system. While the duration of a masticatory cycle+ did not change, the occlusal time significantly decreased after use of the splint. The lateral displacement of the opening phase to the balancing-side area also decreased after use of the splint, showing a vertical pattern of the opening path. Measurement in more healthy individuals and patients should help clarify the therapeutic mechanism of the splint in the treatment of temporomandibular disorders.
Although occlusal splints are useful in the treatment of MPD and internal derangements, they must be used in a rational manner. Two basic appliances are employed in Phase I palliative therapy: a maxillary full coverage (MAR) and a mandibular orthopedic repositioning appliance (MORA). The MAR is used in MPD patients primarily to disengage the occlusion and reduce parafunctional activity. In many cases of internal derangement, protrusive mandibular repositioning is indicated. By using the MORA during the day and the MAR at night, the disadvantages of each appliance are minimized.