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.     

Quantification of the relative risk of multiple occlusal variables for muscle disorders of the stomatognathic system

STATEMENT OF PROBLEM: There is no consensus on the association between occlusion and temporomandibular disorders (TMD). PURPOSE: The purpose of this study was to quantify the relative risk of multiple occlusal variables for muscle disorders of the stomatognathic system. MATERIAL AND METHODS: Eight occlusal features: retruded contact position (RCP) to maximum intercuspation (MI) slide length, vertical overlap, horizontal overlap, unilateral posterior reverse articulation, anterior open occlusal relationship, incisor dental midline discrepancy, mediotrusive interferences, and laterotrusive interferences, were clinically assessed by the same trained operator. The sample consisted of 81 women with a Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) axis I diagnosis of muscle disorder, for example myofascial pain, with or without limited opening, and 48 healthy women (control group). A stepwise multiple logistic regression was used to identify the significant associations between occlusal features and disease. RESULTS: A slide from the retruded contact position to maximum intercuspation > or =2 mm and mediotrusive interferences were the only 2 occlusal features significantly associated with the presence of myofascial pain according to the RDC/TMD criterion symptoms. The odds ratio for myofascial pain was 2.57 for a slide from RCP to MI > or =2 mm and 2.45 for mediotrusive interferences. The percentage of the total log likelihood for myofascial pain explained by the significant occlusal factors amounted to 10.8% (Nagelkerke's R2=0.108). The multifactorial model, including the 2 significant occlusal factors, showed an acuracy to predict disease of 66.7% (sensitivity 71.6%; specificity 58.3%). CONCLUSION: Occlusal features showed a low predictive value to detect muscle disorders of the stomatognathic system. Multifactorial complex pathologies, such as TMD, should be studied using multivariate statistical analyses, as univariate models may overestimate some resulting associations.     

Occlusion and orthodontics.

The importance of considering the functional aspects as well as the static concepts of an occlusion was demonstrated in the case of an 11-year-old girl with postorthodontic temporomandibular joint muscle pain dysfunction. The following characteristics of an ideal occlusion were discussed as they relate to the entire masticatory system: 1. There should be no slide in centric; that is, there should be a stable jaw relationship when occlusal contact is made in centric relation closure. 2. There should be freedom in centric, that is, freedom for the mandible to move from centric relation to centric occlusion and slightly anterior to centric occlusion without interference. 3. Centric relation should be at the same contact vertical dimension as centric occlusion. 4. There should be no buccolingual thrust or impact to any tooth on closure to contact in centric relation or to centric occlusion. 5. Between centric relation and centric occlusion there should be an unrestricted glide with maintained occlusal contact. 6. Complete freedom for smooth-gliding occlusal contact movements in various excursions from both centric occlusion and centric relation. 7. Occlusal guidance should be on the working or functioning side rather than on the balancing or nonfunctioning side. 8. There should be no soft-tissue impingment from occlusal contacts. In effect, the occlusion should be related to centric relation and centric occlusion prior to, during, and at the completion of active treatment. The final occlusion should provide unhindered closure in centric relation, smooth-sliding lateral and protrusive movements, and an optimal bilateral vertical contact dimension. Orthodontic treatment must include proper occlusal adjustment procedures to obtain the goals of an ideal occlusion in most instances.     

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.     

Occlusion and craniomandibular function among patients treated with removable partial dentures

Forty patients treated with removable partial dentures (RPDs) at the Institute of Dentistry, University of Oulu, were selected for this study. The type of occlusion, horizontal and vertical overlap, the slide between retruded contact position and intercuspal position, and the occlusal interferences were investigated as occlusal parameters. Helkimo's anamnestic and clinical indices were used to measure the craniomandibular function and the clinical index score was used to compare the differences between different groups.
The RPD-generated occlusal interferences seemed to cause most harmful effects in point centric, interference free occlusions, when the damage was directed at the temporomandibular joint. These interferences were most frequently found in the retruded contact position and caused by the RPD teeth.     

正中早接触点与颞下颌关节慢性疼痛的关系

目的:定位颞下颌关节慢性疼痛患者的正中早接触点,评价解除早接触干扰对缓解颞下颌关节疼痛的作用。方法:通过面弓转移,记录正中关系,上颌架,测量13例颞下颌关节慢性疼痛患者正中弧差及疼痛指数的变化,并在颌架的介导下去除正中早接触干扰。结果:正中弧差与疼痛指数完全负相关(P<0.001),调牙合可减少疼痛指数和增大正中弧差(P<0.001)。结论:调牙合是改善颞下颌关节慢性疼痛的一种可行方法。     

Electromyographic and patient-reported outcomes of a computer-guided occlusal adjustment performed on patients suffering from chronic myofascial pain

Objectives: Muscular hyperactivity is a potential source of symptoms in patients with temporal-mandibular disorders. An adequate occlusal adjustment may relieve such symptoms. This study aims to measure the effect of shortening the protrusive disclusion time (DT) and balancing the center of occlusal forces (COF) on the EMG recordings and assess the pain reported by chronic patients one month after the computer-guided occlusal adjustment. Study Design: The sample studied comprised 34 patients suffering from chronic facial pain in which the EMG activity of both masseters was recorded by electromyography. By selective grinding we alleviated all the occlusal interferences during the mandibular protrusion from the habitual closure position in order to establish an immediate posterior disclusion and an equilibration of the COF. Results: At follow-up 76.5% of the patients reported no facial pain. Moreover, the EMG activity and protrusive DT were significantly reduced, and occlusal and muscular function were significantly more symmetric than at baseline. Conclusions: According to this EMG study, this computer-guided occlusal adjustment is able to reduce the activity of the masseters and the self-reported muscular pain of patients one-month after treatment. Key words:Myofascial pain, occlusal adjustment, electromyography, T-Scan III, occlusal interferences.     

Occlusal objectives in orthodontic treatment.

An attempt has been made to present a means for preventing the temporomandibular joint pain-dysfunction syndrome by treating to the terminal hinge position and using postreatment occlusal adjustment procedures. 1. Any postorthodontic patient who is not in centric relation and has occlusal interferences has the potential for temporomandibular joint pain-dysfunction syndrome symptoms to develop in the future. 2. The orthodontist should manipulate the mandible of every patient at each visit, placing the condyle in the terminal hinge position. He should close the mandible until initial tooth contact is reached and diagnose the patient's problems from this position and not from the centric occlusion position. 3. The case should be finished with the teeth in centric relation occlusion. 4. The orthodontist should equilibrate the occlusion of every completed case to eliminate the minute occlusal interferences which are always present. 5. The case treated to centric relation can be equilibrated effectively without mounting on an articulator. 6. If we have the concept of building an occlusion to fit the jaw mechanism, the temporomandibular joint pain-dysfunction syndrome can be virtually eliminated in the postorthodontic patient.     

长正中《牙合》型下颌全口义齿近中移位量的初步研究

目的 探讨无牙颌患者戴用长正中<牙合>型全口义齿3个月后下颌义齿的近中移位量能否满足患者长正中量的自然要求,从而检验长正中<牙合>型全口义齿的设计理论. 方法 为10例无牙颌患者制作长正中<牙合>型、线性<牙合>型和解剖<牙合>型3种全口义齿,采用哥特式弓描记装置测量无牙颌患者的长正中量,采用三维精密平移台测量3种<牙合>型下颌义齿的近中移位量.对比分析不同<牙合>型下颌义齿近中移位量的差异,并与患者长正中量进行对比. 结果 10例无牙颌患者的长正中量为(1.02±0.36)mm,3种<牙合>型下颌义齿的近中移位量分别为:长正中<牙合>型(1.016±0.348)mm,线性<牙合>型(1.092±0.448)mm,解剖<牙合>型(0.409±0.253)mm. 结论 长正中<牙合>型全口义齿能满足患者长正中量的自然要求,以及在患者正中关系位至肌力闭合道终点的位置之间无障碍的义齿设计要求.     

Perceived malocclusion and other teeth-associated signs and symptoms in temporomandibular disorders

This article reports the results of a clinical study that evaluated adjunctive teeth-associated signs and symptoms before and after nonsurgical temporomandibular disorder therapy. Eighty-nine patients were referred to a private prosthodontic practice in the Washington, DC metropolitan area. Of the 89 patients, 75 were selected for the clinical study after completing the interview, history, and clinical examination. The major signs and symptoms were recorded, along with adjunctive teeth-associated signs and symptoms. The treatment included an anterior programming device, a centric relation occlusal device, and, when indicated, a selective occlusal equilibration. The results were recorded after five treatment visits. Of 75 patients, 67 made good-to-excellent improvement in the signs and symptoms of their major temporomandibular disorder. Patients with adjunctive teeth-associated signs and symptoms demonstrated a marked reduction in these signs and symptoms as assessed by their mental perception and verbal feedback. The symptoms of perceived awareness of malocclusion were not resolved with centric relation occlusal device therapy in 22 of the 24 patients with this symptom. However, excellent improvement was noted in this symptom when occlusal device therapy was followed by a selective occlusal equilibration. Thirty-eight patients in this study had difficulty in making lateral gliding articulation movements with the occlusal device out of the mouth. This problem was resolved in 36 patients after removal of eccentric occlusal interferences. It is suggested that adjunctive teeth-associated signs and symptoms be initially recorded and addressed in patients, especially if extensive or invasive dental therapy is planned. Although this clinical study in a private practice was carefully performed, it does not meet the criteria of evidence-based research, because a control group was not included.     

Occlusal conditions just after the relief of temporomandibular joint and masticatory muscle pain

When the signs and symptoms of temporomandibular joint disorders (TMD) are present, it is possible that occlusal conditions and mandibular movements are changed. Accordingly, the presence of occlusal interferences may be misjudged. It is therefore reasonable to consider that occlusal conditions should be examined just after the relief of symptoms. The comparison of occlusal conditions in 52 temparomandibular joint (TMJ) pain patients and 27 muscle pain patients with that in 60 asymptomatic controls was made. Occlusal examination in the patients was administered just after the relief of pain by bite plane therapy alone. The only occlusal factor which was associated with pain symptoms was no canine contact on the working side on laterotrusion. It is suggested therefore that further studies as regards this type of interference should be performed.     

Frequency of symptoms of mandibular dysfunction in young Swedish men

The occurrence of symptoms of dysfunction of the masticatory system was studied in 253 Swedish men from the region of Stockholm with an average age of 19 years. Besides inquiry by questionnaire regarding subjective symptoms a clinical functional examination of the masticatory apparatus was performed. Fourteen per cent were aware of clicking of the temporomandibular joint and 12% of other symptoms of dysfunction such as difficulties in opening the mouth wide, locking and pain on performance of various movements of the mandible. In the clinical investigation, symptoms of dysfunction were noted in 28 % of those examined, mainly in the form of tenderness to palpation over the temporomandibular joints and of the masticatory musculature as well as difficult, painful and irregular movements of the mandible. Individuals with clinical symptoms of dysfunction of the masticatory system had a higher frequency of other joint and muscle symptoms, clicking of the temporomandibular joint and occlusal disturbances in the form of balancing side interferences, than those without clinical symptoms. Balancing side interferences were the only occlusal disturbance that was significantly correlated with the symptoms of dysfunction (pain on movement and tenderness to palpation).     

The relationship between the occlusal interference side and the symptomatic side in temporomandibular disorders

This study aimed to investigate the relationship between the facial side of pain or clicking symptoms and the side of occlusal interference, and to examine the features of pain and clicking patients in terms of frequencies of occlusal interferences in relation to the symptomatic side. Occlusal conditions in 31 pain patients and 40 clicking patients were investigated just after the relief of pain or clicking solely by means of bite plane therapy. The symptomatic side did not associate with the side of fewer occlusal contacts in intercuspal position, no canine contact on the working side, occlusal contact on the non-working side, or unilateral contact in retruded contact position. The results of this study suggest that pain or clicking does not necessarily tend to appear on the side of these occlusal interferences. Additionally, characteristic inclination for pain and clicking patients in terms of frequencies of occlusal interferences in relation to the symptomatic side was not identified.     

Comparison of treatment options for myogenous temporomandibular dysfunction

A randomized clinical trial which included a follow-up of one year was applied to 118 myogenous TMD-patients. The therapies investigated were: physiotherapy of the masticatory system or splint therapy for patients without occlusal interferences, and occlusal adjustment therapy or the combination of splint and occlusal adjustment therapy for patients with pronounced occlusal interferences. Counseling, which yielded a reduction of 27% of the scored pain intensity, will most likely eliminate any further need for treatment of patients with a low level of myogenous TMD signs and symptoms. Otherwise, physiotherapy might be preferred as a starting option with respect to splint therapy because of 1. A similar efficacy; 2. A shorter treatment duration so that either chronic facial pain is earlier relieved or a patient can undergo a second type of therapy earlier; and 3. Lower costs. One third of the patients selected had pronounced occlusal interferences. Using stringent criteria it might be possible to apply occlusal adjustment therapy without involvement of splint therapy yielding a similar therapy efficacy and with advantages of a shorter treatment duration and lower costs. All types of therapy diminished not only facial pain but also pain of neck and shoulder areas.     

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.     

Centric relation. Its effect on occluso-muscle harmony.

The most common cause of pain in the region of the temporomandibular joint is occluso-muscle imbalance. This results most often from disharmony between the articulation of the teeth and the centric relation of the condyles. Muscle tenderness of palpation indicates that muscle is involved. An examination must then be done to determine the cause of the muscle tenderness. Before the condyle-occlusion relationship can be evaluated, an accurate centric relation must be determined and verified. The condyles are in centric relation when they are in the most superior position possible in the fossae. From that apex of force position, the condyle can travel neither forward nor backward without moving downward. This position can be located with careful bilateral manipulation and then verified if it can resist firm pressure with no tension or tenderness. Until this correct centric relation is located and verified, it is not possible to properly evaluate the occlusal relationship to the temporomandibular joints. If the occlusion is harmonized to a centric related condyle that can resist firm pressure with pressure with no discomfort, there will be no reason for the muscles to protect either the teeth or the joints. If an occlusion is adjusted to a malrelated condylar position, the occluso-muscle imbalance will be perpetuated and often intensified. Centric relation is the starting point of occlusal contact. Incline interferences in excusive movements must also be eliminated and the occlusion must be harmonized to the envelope of function for each patient. If centric relation is not properly located, occlusal interferences will remain regardless of what procedures are used to record or adjust excursive movements.     

The association of occlusal contacts with the presence of increased periodontal probing depth

Aim: This study evaluates relationships in humans between various occlusal contacts and the presence of deeper probing depths, reduced width of keratinized tissue, and less than favourable initial prognosis. Materials and Methods: The tooth level relationship between various occlusal contacts and pocket probing depths, width of keratinized gingiva, and prognosis at the time of initial examination was evaluated (multivariate model) in a group of patients (85 patients, 2219 teeth) with active periodontal disease. Results: The following were noted to be associated with significantly deeper pocket probing depths: premature contacts in centric relation (0.89 mm, p<0.0001), posterior protrusive contacts (0.51 mm, p<0.0001), balancing contacts (1.01 mm, p<0.0001), combined working and balancing contacts (1.13 mm, p<0.0001), and the length of slide between centric relation and centric occlusion. Protrusive contacts on anterior teeth were significantly associated with shallower probing depths (?0.18 mm, p=0.0076) and a wider zone of keratinized tissue (0.16 mm, p=0.0065). Balancing contacts with and without working contacts and centric prematurities were all associated with an increased incidence of a less than “Good” prognosis Conclusions: Multiple types of occlusal contacts were shown to be associated with deeper probing depths and the increased assignment of a less than “Good” initial prognosis.     

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.     

The relationship between signs and symptoms of temporomandibular disorders and bilateral occlusal contact patterns during lateral excursions

The relationship between signs and symptoms of temporomandibular disorders (TMD) and bilateral occlusal contact patterns was investigated in 143 TMD patients (mean age: 34·0 ± 15·9 years; 38 male and 105 female). In addition to an interview regarding chief complaints and accompanying symptoms various muscles and the temporomandibular joints were palpated bilaterally and occlusal analyses were made. Only 5 out of 108 paired variables were found to be significantly associated by using the chi‐squared test. Medial pterygoid muscle pain on palpation showed significant associations with the occlusal contact pattern ( P < 0·005), especially working side contacts (interocclusal tooth contacts on the working side) ( P < 0·005), during contralateral excursions; sternocleidomastoid muscle pain on palpation showed a significant association with balancing side contacts (interocclusal tooth contacts on the balancing side) during ipsilateral excursions P < 0·05); shoulder stiffness and pain in the eye showed significant associations with balancing side contacts during contralateral excursions ( P < 0·05). The results show only a weak relationship between some TMD symptomatology and bilateral occlusal contact patterns during lateral excursions. The findings suggesting the specific laterality of a few TMD signs and symptoms associated with particular occlusal contacts may deserve closer case–control study.     

A Positional Analyzer for Measuring Centric Slide

Centric relation (CR) has been considered mainly as a position posterior to habitual occlusion or maximum intercuspation (MI). Awareness of the tooth contacts relationship in centric relation position of the mandible and diagnosing the case from this position is essential to consistently select treatment plans that will allow to treat to or very near to centric relation occlusion. Centric slide and other occlusal relationships are conceived of as positions, which can be studied in three dimensions. Clinically, the difference between the two occlusal positions namely CR and MI (centric slide) can easily be determined, but for a more precise evaluation of its length and directions, an occlusal analysis on articulator mounted casts is necessary. Study was under taken on the mounted casts of ten subjects on a semi adjustable articulator to which a stylus and recording table was devised and attached for measurement of CR-MI slide in the three planes namely anterior-posterior, medio-lateral and superior-inferior. It was found that there was a displacement from CR to MI (centric slide) in all the three planes and numerically the mean slide was 0.688 ± 0.623, 0.261 ± 0.627 and 0.127 ± 0.541 mm in the antero-posterior, medio- lateral and superior-inferior directions respectively. The stylus and table attachment may be an accurate indirect method to measure positional changes of the condyle in 3D.