Centric Relation Position Research Articles

Radiographic study of condylar position in centric relation and centric occlusion

The present study was conducted to compare the spatial relationship of the condyles to their fossae in the centric occlusion and centric relation positions. Right and left TMJ radiographs were obtained on 40 young adults in the two positions. Direct measurements of the anterior, posterior, and superior spaces between the condyles and their fossae were made on the radiographs. Results were statistically analyzed; the following findings and conclusions were derived: (1) In the centric relation position, both condyles were placed more posteriorly and superiorly in their fossae than in the centric occlusion position. (2) In the centric occlusion position, both condyles were symmetrically placed in their fossae with equal spatial distances anteriorly and posteriorly. (3) Greater spatial differences existed between the centric occlusion and centric relation positions on the left side, which was the orbiting (balancing) side in most subjects. (4) Further studies are needed to develop a more physiologic approach for correctly relating the mandible to the maxillae when reconstructing the occlusion in both dentulous and edentulous patients.

Fabrication of a Maxillary Complete Denture Utilizing the Neuromuscular or Centric Occlusion Position

The patient was unable to wear a maxillary complete denture that had been made from a verifiable record in the centric jaw relation position or terminal hinge position. When she brought her teeth together, only a few touched. Clinical examination showed that this patient had a discrepancy of approximately 3 mm anteroposteriorly and a discrepancy of 1 mm mediolaterally between the terminal hinge position and the centric occlusion or neuromuscular position. A new denture was made for the patient. The neuromuscular position was used as the starting position and as the position of maximum intercuspation (centric occlusion), and the terminal hinge position was used as a mounted border position of reference for occlusal adjustment and equilibration.

Role of condylar position in TMJ dysfunction-pain syndrome

TMJ dysfunction-pain syndrome is multicausal, and each patient has an individual “TMJ dysfunction profile.” Stress has been shown to be a correlated factor as well as occlusion. Strong stress etiology and a placebo effect have been reported in MPD. It was emphasized, however, that MPD does not involve pain or pathology of the TMJ itself, by definition, and that research (for MPD) is not valid for TMJ dysfunction-pain syndrome which does involve the joint itself, by definition. Condylar position in the fossae of 116 patients was reported, 55 acute TMJ dysfunction-pain and 61 general practice controls. The main findings were that the incidence of condylar retrusion in the acute TMJ patients was 70.9% and condylar concentricity (in the middle of the fossae) was only 3.6%. In the general practice control group, the incidence of condylar retrusion was 36% and condylar concentricity 23%. The incidence of condylar retrusion in the acute TMJ group was twice that in the control [Display omitted] group. Conversely, the incidence of condylar concentricity in the general practice control group was 6.4 times the occurrence in the acute TMJ group. It can be concluded that condylar position in the fossae is a significant factor in TMJ dysfunction-pain syndrome. Furthermore, condylar retrusion occurs much more frequently (71%) than other types of displacement in acute TMJ dysfunction-pain. Condylar retrusion also occurs with enough frequency in the general practice control (36%) to indicate that the “classical” retruded mandibular position of centric relation does not necessarily orient the condyles correctly in the fossae, as is commonly thought. The fact that condylar concentricity (middle of the fossae) was 6.4 times more prevalent in the general practice control group, together with previously reported evidence, confirms (that it is the optimum position in the glenoid fossae. Since the condylar position in the fossae is significant, and even in asymptomatic patients one third can be retruded, TMJ radiography and occlusal evaluation are indicated in almost all patients.

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.

Procedural problems in using the Denar pantograph as a transfer-bow

A method has been described for using zinc-oxide/eugenol paste as an interclutch support when the Denar pantograph is used as a transfer-bow. Using this technique a stable centric relation position can be maintained during the maxillary cast mounting procedure and the subsequent setting of the articulator to the pantographic recordings.

Diurnal variance of centric relation position

Diurnal variance of centric relation position

A comparison of empirical centric relation records with location of terminal hinge axis and apex of the Gothic arch tracing

T h e , problem of acquiring and transferring dependable jaw relation records has long been of interest to prosthodontists. Astute observers have realized the importance and necessity 6f the centric jaw relation position for the development of an occlusion that is in harmony with the entire stom~ tognathic system. Present clinical procedures dictate an even greater interest in accurate jaw relation records. The development of air turbine cutting instruments, fully adjustable articulatgrs, indirect impression techniques, and improved casting procedures has influenced the profession to a greater acceptance of the concept of complete occlusal reconstruction. We know that nature provides a centric relation position at birth and that, at about age 23 months, the mandible exhibits all possible movement, centric occlusaI position is coincident with centric relation position, and an occlusal sense is developed. ~ Throughout life, occlusions are subjected to wear, loss, and repositioning of teeth until 75 per cent of the adult population exhibits a habitual vertical position of occlusion anterior and/or lateral to the centric jaw relation position. ~

Telemetric comparison of centric relation and centric occlusion reconstructions

Two complete fixed prostheses built with the occlusion in centric relation and with occlusion in the subject's existing centric occlusal position were tested with telemetry under conditions of actual use. The findings indicate that the subject did not use the centric relation position but accepted the prosthesis built to her preexisting centric occlusion. These findings are consistent with our previous results of telemetric studies conducted on patients with three-unit fixed prostheses.

A comparison of articulator mountings made with centric relation and myocentric position records

A comparison of articulator mountings made with centric relation and myocentric position records

Reliability of the physiologic method for registering the centric relation position (A clinical study in 100 edentulous patients)

Conclusion : The centric relation registered by the physiologic method is quite satisfactory for the majority of cases. But this method can only give the position of the mandible in the habitual manner in which the patients have for their lifetime, and if done properly, satisfactory set of dentures can be constructed.

Interocclusal Centric Relation Records for Articulator Mounted Casts

Casts can be mounted and verified on a semi-adjustable or fully adjustable articulator using this record system. The success of the indirect technique of diagnosis and treatment is dependent upon accurately mounted casts. It is the duplication of the centric jaw relation position, not the articulator type, that determines whether or not the patient's occlusal contact relations have been simulated. Eccentric articulator adjustments are important but their significance is dependent upon mounting the casts accurately.

Centric occlusion, centric relation, and the mandibular posture

Centric occlusion is a functional relationship of the teeth. Centric relation, often serving to establish the horizontal aspect of a planned centric occlusion, is a maxillomandibular orientation. Dentists often use techniques for recording centric relation that are not functional. Most patients will terminate their functional cycle of mastication with the mandible in the position of centric relation when the centric occlusion is developed in this position. Those patients who do not return their mandibles to centric relation during function may have their problems diagnosed early, when a complete tissue conditioning training denture procedure is employed. They may be given the opportunity to develop their optimum mandibular posture by this treatment.

Evaluation of the needle point tracing as a method for determining centric relation

Summary 1. Needle point tracings were obtained from ten subjects at five different degrees of jaw separation. 2. All subjects showed anteroposterior change of the centric relation position as a factor of increases in the vertical dimension between the jaws. The mandibular centric relation position moved posteriorly when the vertical dimension between the jaws was increased. 3. Two subjects showed only negligible lateral deviations at any degree of opening while one subject showed consistent deviations from the midline when the vertical dimension between the jaws was increased. 4. The needle point tracings at a given vertical dimension of jaw separation under the same controlled conditions, on the same individual, at the same sitting, were not significantly different. On the basis of this study, the needle point tracing procedure is reliable.