A technique for evaluation of centric relation tooth contacts. Part II: Following use of an occlusal splint for treatment of temporomandibular joint dysfunction

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.     

Temporomandibular joint function and its effect on centric relation

An occlusal analysis in relation to the TMJ radiographs will reveal factors that should be added to the purely clinical definition of centric relation. It has been previously established that bilateral asymmetric TMJ spaces and condylar retrusion or protrusion are most often associated with disc derangement and/or palpable muscle spasm.⁴ Conversely, bilateral TMJ space symmetry and condylar concentricity (condyle centered in the superior portion of the glenoid fossa) are associated with joint and muscle health. All TMJ radiographs are obtained with the teeth in the acquired centric occlusion.Centric relation is considered functional when the magnitude and direction of the centric relation deflective slide to the acquired centric occlusion correlate with the condylar displacement observed on the TMJ radiographs. For example, if the patient has a 2 mm. deflective slide straight forward, the centric relation is considered functional when the TMJ radiographs reveal equal condylar protrusion proportional to the mandibular deflection. In the judgment of the dentist, the occlusal correction of the deflective contacts will result in bilateral condylar concentricity. Conversely, centric relation is dysfunctional when the magnitude and direction of the centric relation deflective slide to the acquired centric occlusiondo not correlate with condylar position in the TMJ radiographs. When no deflective slide is present, both condyles should be concentrically located in each fossa with bilateral symmetrical joint spaces in order for centric relation to be considered functional. Dysfunctional centric, relation is often associated with disc derangement and/or palpable muscle spasm. When the centric relation is functional, the most retruded jaw position should be used. If the centric relation is dysfunctional, a therapeutic or treatment centric occlusion must be established by the dentist, utilizing the TMJ radiographs as a guide. In this situation, the most retruded position would be harmful to the patient.     

Occlusal interferences and temporomandibular dysfunction

Disagreement exists regarding the relationship between occlusal interferences and temporomandibular joint dysfunction (TMD). This study sought to determine how a balanced occlusion, providing uniform contact in centric relation, would affect signs and symptoms of TMD. A randomly chosen group of 60 patients with occlusal interferences and signs and symptoms of TMD used a mandibular orthotic to balance their occlusions at centric relation (CR). When the occlusions of symptomatic patients were balanced in CR, there was a significant reduction or elimination of TMD complaints, suggesting a relationship between balancing occlusion in CR and optimum management of TMD.     

An appraisal of the literature on centric relation. Part II

The literature directly and indirectly related to centric relation (CR) has been reviewed chronologically. More than 300 papers and quoted sections of books have been divided into three sections. The first two parts of the paper are related to CR. Studies in this group mainly compared either the position of the mandibular condyle or the mandible itself in different CR recordings. Various tools were discussed for this purpose. The third part deals with CR-centric occlusion (CO) discrepancy. CR remains one of the controversial issues in prosthodontics and orthodontics. Debates relating to mounting casts on the articulator by reproducible records for orthodontic treatment planning and end results, and whether or not orthodontic treatment based on CO causes temporomandibular joint (TMJ) dysfunction, remain unsolved. The references are listed at the end of Part III.     

Relationship between occlusal factors and signs and symptoms of mandibular dysfunction. A clinical study of 48 dental students

Forty-eight young adults answered a questionnaire and were examined clinically for determination of symptoms and signs of mandibular dysfunction in accordance with the Helkimo indices. Occlusal conditions recorded included contacts in centric and excentric mandibular positions in accordance with specified criteria for registration of "ideal occlusion', various occlusal patterns, occlusal interferences, and dental attrition. Relatively frequent but mainly mild signs and symptoms of mandibular dysfunction were found. The occlusal conditions were extremely varied and did not show any significant correlations with signs and symptoms of mandibular dysfunction.     

Incidence and prevalence of temporomandibular joint pain and dysfunction. A one-year prospective study of university students

Objective. The aims of this study were to investigate the incidence and recovery of temporomandibular joint (TMJ) pain and dysfunction during a 1-year period, and to examine factors associated with TMJ signs and symptoms. Material and Methods. The study population comprised 371 dental students examined at the start of education, out of which 308 were re-examined after 1 year. Case histories were collected with the aid of a questionnaire. The clinical examination involved TMJ mobility, TMJ pain, TMJ sounds, morphological and functional dental occlusion. Results. The 1-year incidence of TMJ signs and/or symptoms was 12%, with no statistically significant difference between men and women. Reported TMJ sounds (10%) and clinically registered TMJ pain (8%) reached the highest incidence rates. Approximately a quarter of those who had TMJ signs and/or symptoms at baseline had recovered at follow-up. Subjects with a non-symptomatic TMJ were significantly more often found among men and among those with bilateral contacts in centric relation, a normal transverse inter-maxillary relationship, and a stabile mandibular position in centric occlusion. Conclusion. The 1-year incidence of TMJ pain and/or dysfunction was high among 1st-year university students. The persistence of signs and symptoms during the observation period was related to gender, while incidence and disappearance of symptoms were not. Dental occlusion was not rejected as a possible concurrent factor in relation to TMJ pain and/or dysfunction among university students.     

The effect of changing the maxillomandibular relationship by a bite plane on the habitual mandibular opening and closing movement

The relationship between the change of afferent information from occlusal contacts and its influence on the jaw muscles was investigated. For this purpose, the following questions were posed and experimental studies designed. If the subject was given habitual occlusal contacts in centric relations with a bite plane, were the habitual mandibular closing and opening movements influenced? Second, was it easier for the subjects to accomplish regular habitual mandibular opening and closing movements, when the bite plane was inserted and removed? From the results it could be concluded that the centric occlusal contacts in centric relation were more physiological for the jaw muscles. In addition, when the new occlusal position was coincident or close to the centric relation, it was easier for the subject to study and acquire the new habitual mandibular opening and closing movement.     

Incidence and prevalence of temporomandibular joint pain and dysfunction. A one-year prospective study of university students

OBJECTIVE: The aims of this study were to investigate the incidence and recovery of temporomandibular joint (TMJ) pain and dysfunction during a 1-year period, and to examine factors associated with TMJ signs and symptoms. MATERIAL AND METHODS: The study population comprised 371 dental students examined at the start of education, out of which 308 were re-examined after 1 year. Case histories were collected with the aid of a questionnaire. The clinical examination involved TMJ mobility, TMJ pain, TMJ sounds, morphological and functional dental occlusion. RESULTS: The 1-year incidence of TMJ signs and/or symptoms was 12%, with no statistically significant difference between men and women. Reported TMJ sounds (10%) and clinically registered TMJ pain (8%) reached the highest incidence rates. Approximately a quarter of those who had TMJ signs and/or symptoms at baseline had recovered at follow-up. Subjects with a non-symptomatic TMJ were significantly more often found among men and among those with bilateral contacts in centric relation, a normal transverse inter-maxillary relationship, and a stabile mandibular position in centric occlusion. CONCLUSION: The 1-year incidence of TMJ pain and/or dysfunction was high among 1st-year university students. The persistence of signs and symptoms during the observation period was related to gender, while incidence and disappearance of symptoms were not. Dental occlusion was not rejected as a possible concurrent factor in relation to TMJ pain and/or dysfunction among university students.     

Anterior condylar displacement: Its diagnosis and treatment

A deflective slide in centric relation to centric occlusion does not necessarily mean anterior condylar displacement. Its diagnosis and treatment depend on the correlation of three factors: the direction and magnitude of the mandibular slide from centric relation to centric occlusion, the change in vertical dimension of occlusion during the slide, and the position of the condyles in the fossae when the teeth are in the maximum occlusion (centric occlusion).When the change in vertical dimension almost equals the amount of slide from the deflective contact in centric relation to maximum intercuspation, very little anterior condylar displacement would be expected. Conversely, with proportionately little change in vertical dimension, more anterior condylar translation is required for a given degree of anterior slide. Examples of each type of anterior slide were related to the TMJ radiographs of the condylar position. If the direction and magnitude of the deflective occlusal contact can be correlated with the TMJ radiographs, the centric relation is “functional,” and the clinically retruded mandibular position should be used. When this correlation does not exist, the centric relation is “dysfunctional,” and the terminal hinge position (retruded mandibular position) shouldnot be used for restorative or corrective procedures. Examples of anterior condylar displacement were given, including lateral deviation, with a comparison of “before” and “after” TMJ radiographs.     

An evaluation of occlusal factors in TMJ dysfunction-pain syndrome.

TMJ dysfunction-pain has four main sources: intrajoint, muscle spasm, joint/muscle, and referred. Electromyographic evidence has been cited to show that there is a direct cause-and-effect relationship between occlusal deflective contacts and muscle spasm. In some patients emotional stress can be the primary etiologic agent in TMJ dysfunction-pain syndrome, but it works indirectly through the tension-relieving mechanism of bruxism. The controversy over the relative importance of stress and occlusion as a primary etiologic agent remains active. It has been suggested that the reason this conflict has remained unresolved is because the criteria for “malocclusion” is indefinite.The clinical assumption that “when the mandible is in the most retruded position of centric relation, both condyles are in correct alignment in the glenoid fossa” has been challenged. The centric relation of each patient should be individually evaluated by comparing the clinical occlusal findings with the TMJ radiographs. Sometimes the clinical centric relation is not healthy (dysfunctional) and the suspension mechanism of the TMJ is faulty. Condylar displacements are caused by a lack of harmony between the occlusion and the resulting orientation of the mandible. The absence of posterior tooth support can also lead to posterior or superior condylar displacement. The evaluation of occlusal factors in TMJ dysfunction-pain syndrome should not be a mere tabulation of the “hit and slide” but should contain an evaluation of the relative health of the suspension mechanism of centric relation itself.Recent research into the functional parameters of the condylar suspension mechanism indicates that muscles rather than ligaments determine posterior and inferior condylar position. Superior condylar position is influenced by the posterior teeth and meniscus. These observations and experiments have produced a “biophysical” concept of the condylar suspension mechanism. The teeth, muscles, and disc support and guide the condyle in its suspension within the fossa.In adults, alterations in mandibular position will not produce a “corrective remodeling” of the TMJ, and pathologic changes can take place. The TMJ will attempt to physiologically accept condylar displacement; however, in most people, joint and/or muscle dysfunction develops. The level of dysfunction in many patients remains subclinical.The objective of treatment is to correct the occlusion so that the displaced condyles can be repositioned in the middle of the fossa evenly (symmetrically) on both sides. The therapeutic procedure is different in each patient, depending on the type of condylar displacement involved so that a balanced biophysical relationship is established between the teeth, muscles, and TMJ.     

An appraisal of the literature on centric relation. Part III

The literature directly and indirectly related to centric relation (CR) has been reviewed chronologically. More than 300 papers and quoted sections of books have been divided into three sections. The first two parts are related to CR. Studies in this group mainly compared, either the position of the mandibular condyle or the mandible itself in different CR recordings. Various tools were discussed for this purpose. The third part of the paper is about CR-centric occlusion (CO) discrepancy. CR still remains one of the controversial issues in prosthodontics and orthodontics. Debates such as mounting casts on the articulator by reproducible records for orthodontic treatment planning and end results, and whether or not orthodontic treatment based on CO causes TMJ dysfunction, remain unsolved. The references are listed at the end of Part III.     

Analysis of the mandibular relationship of TMJ dysfunction patients using the Mandibular Kinesiograph

Analyses of the relationship between centric relation and centric occlusion were performed using the Mandibular Kinesiograph to show the abnormality of mandibular positions of the TMJ dysfunction patients. The distance between centric relation and centric occlusion in antero-posterior, left, and linear direction showed significant differences between the normal subjects and the TMJ dysfunction patients. In the TMJ dysfunction patients, the number of the subjects who showed larger deviation between centric relation and centric occlusion increased remarkably when compared with normal subjects. It is suggested that the slide between centric relation and centric occlusion can be one of the causes of the TMJ dysfunction.     

Occlusion and mandibular dysfunction: a clinical study of patients referred for functional disturbances of the masticatory system

Fifty patients were selected according to age (less than 40 years) and dentition (full complement of natural teeth) from a large group referred for treatment of functional disturbances of the masticatory system. They answered a questionnaire and were examined clinically for evaluation of the severity of their symptoms and signs according to the Helkimo dysfunction indexes. The occlusal conditions recorded included contacts in centric and eccentric mandibular positions, various defined occlusal patterns, occlusal interferences, and dental attrition. The occlusal conditions varied considerably but did not show significant correlations with signs and symptoms of mandibular dysfunction. These results suggest that the occlusal variables studied do not contribute to the severity of the signs and symptoms of dysfunction. While it is tempting to propose that our results suggest an argument for dysfunction, it must be admitted that the precise role of occlusion remains unclear.     

Prevalence of mandibular dysfunction in young adults.

A sample of students (739) were questioned and examined for symptoms and signs associated with mandibular dysfunction. The most frequently mentioned symptoms were headache, TMJ sounds, and pain in the face or neck. No significant differences were found between men and women with symptoms other than headache. The most common dysfunctional signs were dull occlusal sounds on repeated, firm closure of the teeth, tenderness of muscles in the jaw or head, and sounds on condylar movement. Women had a higher prevalence of these signs. Subjects who were aware of bruxism (7.9%) were more likely to have tenderness of the masseter muscle and limited mouth opening. Limited mouth opening was associated with dull occlusal sounds, pain on opening the mouth, and sounds in TMJs. Headaches were associated with tenderness in muscles and joints. Subclinical signs associated with dysfunction occurred more frequently than did awareness of symptoms.     

Mandibular dysfunction in an institutionalized and predominantly elderly population

Oral health problems were identified among 653 residents of 40 long-term care institutions in Vancouver, using a personal interview and a dental examination. Information on jaw function was analysed as part of this investigation to identify associations between the clinical signs of mandibular dysfunction and the complaints of the subjects, their occlusal instability, and the quality of their dentures. The sample population were predominantly female and over 75 years of age, and 42% had some natural teeth. Complaints of jaw dysfunction, usually sore muscles, were heard from 13% of the 488 subjects interviewed. The examination was performed on all of the subjects and revealed that 43% had unstable occlusal contacts, 37% were using loose or unstable dentures, and 20% had one or more clinical signs of jaw dysfunction. Joint noise was the most frequent sign detected and it was heard in a greater percentage of the women than men, while deviation of the mandible during mouth opening was observed with great frequency in the younger age groups. There was no apparent association found between the clinical signs of jaw dysfunction and the complaints of the subjects or the condition of their teeth or dentures. The study demonstrated that complaints and clinical signs of jaw dysfunction, with the exception of joint noises, were uncommon in this population.     

Temporomandibular disorders. Part II: Occlusal factors associated with temporomandibular joint tenderness and dysfunction

Two complete classes of freshman dental and dental hygiene students, 120 men and 102 women (mean age 23.9 years) were assessed for the presence of masticatory pain or dysfunction by questionnaire, clinical examination, and evaluation of dental casts according to strict criteria. The purpose was to identify the degree of association between observable signs of TMJ disorders and selected combinations of occlusal variables. TMJ tenderness was more frequent in class II, division 2 than in class I (p less than .05), but overall was not associated with occlusal factors such as deep overbites, length of a symmetric RCP-ICP slide, and unilateral contact in RCP. Overall, clicking was not associated with Angle class, deep overbite, length of symmetric RCP-ICP slide, or unilateral RCP contact. Among subjects with unilateral RCP contact, those with no clinically obvious RCP-ICP slide (p less than .005) and those with asymmetric slides (p less than .05) had more TMJ clicking than subjects with symmetric slides. Luxation clicking of the condyle over the articular eminence on wide opening was absent in class II, division 2 subjects, but was most frequent in subjects with some teeth in unilateral posterior crossbite, particularly when this was a unilateral condition (p less than .001). Certain occlusomorphologic conditions may require less adaptation in the TMJs. This article indicates that an ICP anterior to the RCP in association with bilateral occlusal stability may be protective.     

Constancy of clinical signs in patients with mandibular dysfunction

Repeated clinical examinations were performed 6 weeks apart on 34 patients with mandibular dysfunction to estimate the consistancy of clinical signs. The clinical examination of the patients included the masticatory muscles, the temporomandibular joint (TMJ) and the mandibular movement capacity. The clinical dysfunction index (Di) was calculated as a measure of the degree of mandibular dysfunction. The highest agreement between examinations was found for maximal mouth opening and protrusion. The agreement for palpation tenderness of the masticatory muscles and TMJ, limited movement of the TMJ, TMJ sounds, and pain during movement was considerably lower. The lowest agreement within 6 weeks was found for the clinical dysfunction index. No statistically significant difference could be detected between the two examinations for any of the clinical signs, as a result of given information and counseling before the 6-week period. It was concluded that all clinical signs, except maximal mouth opening and maximal protrusion, showed low consistancy.     

An appraisal of the literature on centric relation. Part I

The literature directly and indirectly related to centric relation (CR) has been reviewed chronologically. More than 300 papers and quoted sections of books have been divided into three sections. The first two parts are related to CR. Studies in this group mainly compared either the position of the mandibular condyle or the mandible itself in different CR recordings. Various tools were discussed for this purpose. The third part of the paper is about CR-centric occlusion (CO) discrepancy. CR still remains one of the controversial issues in prosthodontics and orthodontics. Debates such as mounting casts on the articulator by reproducible records for orthodontic treatment planning and end results, and whether or not orthodontic treatment based on CO causes temporomandibular joint dysfunction, remain unsolved. The references are listed at the end of Part III.     

Conservative interdisciplinary treatment of a case with multiple facial and condyle fractures

The purpose of this case report is to describe an interdisciplinary approach for a 51‐year‐old male who underwent multiple facial fractures including bilateral condyle fractures. The patient underwent emergency surgery, which included open reduction of the maxilla and mandibular symphysis and closed reduction of the bilateral condyle fractures. Although the patient recovered a comfortable range of mouth opening and alleviation of the temporomandibular joint (TMJ) symptoms after surgery, he suffered from a large anterior–posterior discrepancy due to less stability on the condyle‐fossa relationships and from open bite with contacts only on both second molars and right second premolars. In this case, first, to increase the occlusal contact, comprehensive orthodontic treatment was completed. Second, occlusal equilibration was selectively performed to relieve the interferences and establish a stable range of mandibular movement without any changes in the vertical dimension. Third, both the upper central incisors and left lateral incisor were minimally restored with splinted and single zirconia crowns, which had modified lingual contours to provide adequate anterior guidance permitting the anterior–posterior discrepancy of the posterior teeth during protrusion. This conservative interdisciplinary treatment, including open and closed reduction, orthodontic treatment, occlusal adjustment, and minimal prosthetic restorations, resulted in a stable mandibular position and recovery of mastication function.     

Short term evaluation of counselling and occlusal adjustment in patients with mandibular dysfunction involving the temporomandibular joint

The effect of counselling and occlusal adjustment was investigated in thirty patients with mandibular dysfunction involving the temporomandibular joint (TMJ). The patients were examined at three visits 6 weeks apart. At the first visit all patients received counselling. At the second visit they were divided into two groups, one receiving occlusal adjustment and the other not receiving treatment. The degree of mandibular dysfunction was assessed by the patients according to a five grade scale and by the clinical dysfunction index according to Helkimo (1974a). The score of subjective dysfunction was reduced significantly during the period following counselling and 60% of the patients improved. No effect was found on the clinical dysfunction score. The score of clinical dysfunction was reduced significantly during the period following occlusal adjustment and 67% of the patients improved. No further effect could be detected on the subjective dysfunction score. The correlation between changes in subjective and clinical dysfunction was poor, but changes in the subjective score were generally associated with changes in the clinical score. It was concluded that counselling may reduce the subjective symptoms; and occlusal adjustment the clinical signs of mandibular dysfunction involving the TMJ, but that the individual variation in response is substantial.