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At least 163 records · Page 9Linked to original sources

PubMed1981

Centric relation determinations: clinical and radiographic comparisons.

This study investigated variations in occlusal prematurities and condylar positions using different methods of determining centric relation. Thirty patients were randomly placed into three groups of 10. In Group I a clinical analysis of occlusal patterns using bilateral mandibular manipulation (BMM) was compared to results with a chin point (CPM) method. Group II compared CPM to an anterior guidance jig (CPJ) method. Group III compared BMM to CPJ. Standardized transcranial oblique radiographs were taken of each temporomandibular joint using CPM and BMM on 10 patients. Condylar position was determined with tracing evaluations and direct measurements of the radiographs. Clinical results indicated that the initial point of contact was located most accurately with CPJ. Both initial contact points and secondary points were disclosed with CPM. The BMM disclosed the most tooth contacts. Contacts were most prevalent on the premolars. Radiographic analyses of condylar positions were inconclusive.

Adult↗

PubMed1978

Treatment prostheses in TMJ dysfunction-pain syndrome.

Various types of acrylic resin therapeutic prostheses commonly used in the treatment of TMJ dysfunction-pain syndrome were described. Each design was related to recent data concerning optimum condylar positions in the fossae, the physiologic condylar suspension system, and individual treatment objectives for repositioning the mandibular condyles. For example, alteration of the vertical dimension of occlusion is a popular treatment procedure that is empirical in nature and is usually used without TMJ radiographs or a differential diagnosis. It can violate the physiologic requirements of the interocclusal distance or the speaking space and does not necessarily move the condyles forward as has been commonly thought. The dangers of empirical treatment procedures for a multicausal dysfunction syndrome have been pointed out. An example was cited where the mandible was moved forward for a long period of time with a repositioning prosthesis; this produced pathologic TMJ remodeling and continued pain. It was recommended that specific mandibular repositioning be based on the type of condylar displacement observed on the radiographs. Sometimes the condyles should be retruded, and other times they should be repositioned anteriorly or occasionally inferiorly on one side. Long-standing use of any acrylic resin repositioning prosthesis is contraindicated, particularly without close supervision. Acrylic resin anterior bite plates (with a minimum opening of 1 mm) were recommended for the relief of acute trismus or intractable pain. Usually the prosthesis is used in conjunction with heat and drug therapy. This type of prothesis can also be utilized to deprogram the muscles when a strong habit of eccentric occlusion develops as a result of missing teeth. (This should be confirmed by TMJ radiographs.) Occasionally atypical pain is present and a differential diagnosis can be established between TMJ dysfunction or neurologic etiology by the physiologic response to bite plate therapy. When it is necessary to reposition the mandibular condyles anteriorly the occlusion is adjusted to provide the planned anterior movement without increasing the vertical dimension of occlusion. A temporary acrylic resin prosthesis is used to retrain the muscle programming to the anterior therapeutic mandibular position. When the symptoms are relieved and the corrective condylar position is confirmed with TMJ radiographs, a more permanent repositioning prosthesis is made. The treatment of TMJ dysfunction-pain syndrome should be based on documented data including the pain history, TMJ radiographs, condylar position in the fossae, electromyographic evidence, and occlusal analysis. This information will help determine if the patient's centric relation is functional or dysfunctional and will indicate the recommended treatment procedures.

Acrylic Resins↗

PubMed1996

Tomographic assessment of temporomandibular joints in patients with malocclusion.

There is a paucity of information on the morphological assessment of the temporomandibular joint in relation to varying skeletal and dental relationships. The purpose of this study was to evaluate the morphologic relationship of the condyle and fossa in patients with different malocclusions and skeletal relationships. Pretreatment records of 232 orthodontic patients, 95 males and 137 females, of Caucasian descent and ranging in age from 9 years 4 months to 42 years 6 months, were examined. Records included dental casts, lateral cephalometric radiographs, hand-wrist radiographs, and corrected tomograms of right and left TM joints. Nonconcentricity and mild asymmetry of the condyle-fossa relationship were commonly observed. The left condyle was found to be more anteriorly positioned than the right, with the mean percentage of joint space being 6.93% on the left side and -1.24% on the right. Skeletal and dental Class III patients demonstrated significantly more anteriorly positioned condyles (P < 0.05). There were no significant differences in condylar position between Class I and Class II groups based on ANB or Angle's classification. Further, no significant difference in condylar position was observed between groups based on overbite or crossbite.

Adolescent↗

PubMed1997

Positional changes in the mandibular condyle and amount of mouth opening after sagittal split ramus osteotomy with rigid or nonrigid osteosynthesis.

PURPOSE: The purpose of this study was to investigate postoperative positional changes in the mandibular condyle and mouth opening in patients undergoing sagittal split ramus osteotomy with either rigid or nonrigid osteosynthesis. PATIENTS AND METHODS: The forty-six patients with mandibular prognathism underwent sagittal split ramus osteotomy for mandibular set back followed by fixation with one of four methods: circumferential wire (n = 11), lag screw technique (n = 10), positional screw technique (n = 10), or miniplates (n = 15). The changes in the condylar position were assessed by measuring the angle of the condylar long axis (the condylar angle) on submentovertex radiographs. Mouth opening was evaluated by measuring the interincisal distance immediately after the release of maxillomandibular fixation and by monitoring the duration of trismus. RESULTS: Regardless of the procedure used the condylar angle increased in most patients after surgery (80 of 92 condyles). Although the amount of increase tended to be higher with rigid osteosynthesis than with nonrigid osteosynthesis, no significant differences were observed among the groups. Mouth opening was not significantly influenced by the type of osteosynthesis, and no patient complained of limitation 1 year after surgery. CONCLUSIONS: Although inward rotation of the condyle frequently occurs after osteosynthesis regardless of the procedure used, the changes in condylar position are within the range of adaptability of the patient.

Adaptation, Physiological↗

PubMed1997

Studies of changes in occlusion after the insertion of complete dentures (part II).

The aim of this clinical experimental study was to investigate whether, and what, changes in occlusion occur between 3 weeks and 1 year after insertion of complete dentures. Twenty-six edentulous patients, who already had their jaw relation registered for part I of this study some 357 days before, were re-examined. The same special non-arcon measuring articulator was used for determination of any positional differences between the presently recorded central condylar position with inter-occlusal gap and the equilibrated intercuspal position, from approximately 1 year previous. Differences were recorded electronically in the condylar area in three dimensions. The position of the condylar balls of the measuring articulator in maximum intercuspation had shifted, since the previous recording, by about 0.62 +/- 0.04 mm (0.04-1.76 mm) in the sagittal and 0.89 +/- 0.72 mm (0.01-3.06 mm) in the vertical direction. Whereas the differences measured in maximum intercuspation scattered in the sagittal plane uniformly around the centric condylar position, in the vertical plane they were shifted cranially about an average of 0.77 +/- 0.85 mm (1.06 mm caudally to 3.06 mm cranially). The results indicate that in half of the patients from the present sample the occlusion did not remain stable, which is assumed to be mainly caused by resorption of alveolar bone and abrasion of the acrylic teeth. Therefore, at each check-up visit not only the health of the denture-bearing tissues and the fit of the dentures, but also the mandibular posture and the occlusion should be examined carefully.

Acrylic Resins↗

PubMed1988

Unexpected TMJ responses to functional jaw orthopedic therapy.

The activator, the Bionator, the Fränkel, and, more recently, the Herbst appliances have enjoyed increasing popularity. Although an increase in mandibular growth has not been shown to be clinically consistent or always significant, the popularity of these appliances continues. Another clinical goal of these functional jaw orthopedic (FJO) appliances is to correct, maintain, or protect the integrity of the TMJ--specifically, to prevent posterior condylar displacement and/or anterior disk displacement. Because all FJO appliances anteriorly reposition the condyle during treatment, it is hoped that internal derangement problems may be resolved during treatment. Even though a single TMJ radiograph is not diagnostic in itself, multiple radiographs are helpful in monitoring the net changes in the condylar position during treatment. The relative (or net) change in the condylar position may provide clues to what occurred during treatment. However, TMJ responses are not always predictable during FJO treatment. Three case histories are presented that illustrate unexpected TMJ responses in which the condyles were still posteriorly displaced in spite of FJO treatment. Only 2% to 3% of the author's practice responds in this manner and no physiologic mechanism is suggested. These findings point out the complexity of the TMJ and its treatment, regardless of the appliance, and emphasize that no one approach to TMJ treatment will always be efficacious.

Activator Appliances↗

PubMed1980

Centric relation: a comparison of muscle-determined position and operator guidance.

Fifteen subjects were used to determine direction and magnitudes of shifts in condylar position when interocclusal records were made by biting hard or easy on a leaf gauge or wax. Electromyographic recordings were made of the temporal and masseter muscles during interocclusal registrations to determine which muscles were most active in seating the condyle when the leaf gauge was used. Results indicated no significant difference in condylar position superoinferiorly between registrations. Biting hard on a leaf gauge caused a significantly more posterior position of the condyle. When this technique is used for obtaining interocclusal registrations, the temporal muscles are more active than the masseters.

Adult↗

PubMed1991

Maintenance of condyle-proximal segment position in orthognathic surgery.

Twenty patients underwent bilateral sagittal ramus osteotomy for the correction of mandibular retrognathia. A condylar positioning device (CPD) was used intraoperatively in 10 patients to maintain preoperative condyle-proximal segment position, while the CPD was not used in the other 10 patients. Postoperatively, the condyle-proximal segment positions in both groups were compared and evaluated for vertical, horizontal, and rotational changes. A significant improvement (P less than .05) was observed in the vertical and horizontal condylar position in the group in which the CPD was used. However, there was no significant difference in proximal segment rotation.

Adolescent↗

PubMed1994

The reproducibility of condylar hinge axis positions in patients, by different operators, using the electronic mandibular position indicator.

Three operators each made five recordings from 15 symptomatic patients using the electronic mandibular position indicator. The method consisted of measuring bilateral spatial changes of the hinge axis recalculated by the computer to an intercondylar distance of 110 mm and a third position, calculated from the rotation of the hinge axis, at the incisal guidance table. All individual patient recordings were related to the origin of the same coordinate system. This origin is designated and defined as the reference position, with purposeful elimination of any stated joint position for this definition. The measurements were in all planes of space at 10-millimicron increments, including the rotation of the transverse hinge axis in hundredths of degrees. These data showed that the reproducibility of hinge axis positions, ie, reference positions, to hinge axis condylar positions dictated by the maximum intercuspation of teeth was in average less than 0.2 mm for each record from all operators and patients.

Analysis of Variance↗

PubMed1998

An evaluation of digital subtraction radiography for assessment of changes in position of the mandibular condyle.

OBJECTIVE: To compare conventional visual evaluation with digital subtraction for assessing changes in condylar position on TMJ radiographs. METHODS: Horizontally corrected oblique lateral transcranial radiographs of the TMJ were taken bilaterally with and without a stabilisation or a control appliance on the same occasion in 20 patients. All of the radiographs were assessed both conventionally and following digital subtraction by seven observers. Three observers assessed both sets of radiographs twice to calculate observer agreement. RESULTS: There were no statistically significant differences in observer performance or diagnostic outcome between the two techniques. Intra-observer agreement varied between 85 and 90% for the conventional visual evaluation and between 62 and 85% for digital subtraction. Although interobserver agreement was greater with the conventional evaluation the difference was not significant. CONCLUSION: Conventional visual evaluation is recommended for the assessment changes in condylar position from TMJ radiographs.

Adolescent↗

PubMed1985

Repeatability of the mandibular retruded position.

Repeatability of the centric jaw relation recorded with the one-handed push-back technique was tested on six subjects. Condylar positions were radiographically recorded using cold cure acrylic indices to lock the jaws in centric. This was done on two occasions with an interval of 1 week between recordings. Utilizing the subtraction technique, the radiographs of these condylar positions were compared. Intra-individual differences were not found to be significant and it may be concluded that centric relation registered with the push-back technique results in accurate and consistent repositioning of the condyles in the glenoid fossa.

Acrylic Resins↗

PubMed1990

New TMJ clinical data and the implication on diagnosis and treatment.

A review of the literature and the presentation of 220 patients with acute temporomandibular disorders and a control group are presented. Condylar position in the fossae is related to clinical symptoms. Ten important clinical factors were recorded and the data compared without reference to specific condylar position in the fossae and then in relation to condylar displacement groups. The significantly high incidence of posterior condylar displacement and joint pain in the patients described in this report indicates that elimination of the term joint in our definition of this disorder may be premature.

Acute Disease↗

PubMed2004

Forward mandibular positioning enhances condylar adaptation in adult rats.

The aim of this investigation was to assess quantitatively the adaptive changes in the condyles of adult rats to forward mandibular positioning. The level of types II and X collagen expressed in the condyles of adult rats was compared with that formed in response to forward mandibular positioning and the levels of expression were correlated to the amount of bone formed in response to mandibular advancement. Seventy-eight 120-day-old female Sprague-Dawley rats were included in this study. The rats were randomly allocated to six groups. Each group consisted of nine rats with bite-jumping devices and four untreated controls. The animals in each group were sacrificed on days 3, 7, 14, 21, 30, and 60. Immunostaining was used for the detection of types II and X collagen, while Alcian blue-PAS was used to observe the extracellular matrix and new bone formation. The results showed that new cartilage was formed in the posterior condyle. The highest level of expression of types II and X collagen were present on day 21, the amount of increase was 247.99 and 540.08 per cent, respectively. The highest level of new bone formation was measured at day 30 of advancement when the amount of increase in new bone formation was 318.91 per cent. These findings indicate that forward mandibular positioning causes changes in the biophysical environment of the temporomandibular joint (TMJ) of adult rats that leads to condylar adaptation.

Adaptation, Physiological↗

PubMed1990

[An evaluation of the signs and symptoms in patients with craniomandibular disorders correlated with the radiological pictures obtained by OLTP].

The study evaluated the frequency of noise, pain and alterations of mandibular movements in a group of 88 patients. Condylar position was also studied using OLTP X-ray images, and the presence of arthrotic lesions using multitomography. The condylar position was related to the presence of organic lesions at an articular level, and a higher frequency of the latter was found in anterior condylar displacements; the presence of condyles centered in the glenoid cavity on OLTP examination does not exclude the possibility of arthrotic lesions. Another important finding was the observation of a greater frequency of contralateral organic pathologies in posterior condylar displacements.

Adolescent↗

PubMed2004

Positional and morphologic changes of the mandibular condyle after mandibular distraction osteogenesis in skeletal class II patients.

AIM: Mandibular distraction osteogenesis has been used to correct the skeletal problems in patients with severe mandibular deficiency. Short-term effects of mandibular distraction osteogenesis on condylar position, condylar morphology, and temporomandibular joint symptoms in patients with severe skeletal Class II malocclusions were evaluated. MATERIAL AND METHODS: The records of 13 patients who had undergone bilateral mandibular lengthening and/or midline mandibular widening were analyzed. Pre- and postoperative positional changes of the mandibular condyle in the glenoid fossa, the axial rotation of the condylar head, and the temporomandibular joint symptoms were evaluated. RESULTS: Most of the condyles were displaced in an upward and backward direction in the glenoid fossa; the amount correlated with the amount of mandibular lengthening. Resorption was observed in 20% of condyles; the incidence of the resorption correlated with incidence of preoperative articular disc displacement and with the amount of condylar displacement. CONCLUSION: Distraction protocols should be performed with particular attention when patients with articular disc displacement require a large amount of distraction.

Adolescent↗

PubMed2000

Magnetic resonance imaging findings and clinical symptoms in the temporomandibular joint in patients with mandibular continuity defects.

PURPOSE: This study explored the morphologic changes and clinical symptoms related to the temporomandibular joint (TMJ) associated with long-term lack of mandibular continuity. PATIENTS AND METHODS: The subjects were 20 patients (40 TMJs) who underwent mandibulectomy including the condyle or segmental mandibulectomy without mandibular reconstruction more than 6 months previous to the study. The 40 TMJs were classified into the following 3 groups: group I: TMJs with a major mandibular fragment including the mandibular body (n = 21), group II: TMJs with a minor mandibular fragment including only the condylar process or the mandibular ramus (n = 10), and group III: TMJs without a condyle (n = 9). All TMJs were examined with respect to disc position, condylar position, bony changes, and appearance of joint effusion on magnetic resonance imaging, as well as for the presence of joint or muscle pain and joint noise. RESULTS: The rate of anterior disc displacement was 28.6% in group I, 10.0% in group II, and 100% in group III. All condyles in group I were located in the glenoid fossa. Seven of 10 condyles in group II were dislocated anteriorly out of the glenoid fossa. However, these condyles were situated in the intermediate zone of the disc. Osteoarthritic changes was found in 1 joint in group II. Joint effusion was not observed in group I. However, joint effusion was detected in the posterior region of the upper joint compartment in 7 of 10 TMJs in group H and in 8 of 9 TMJs in group III. In group II, the 7 TMJs with joint effusion were the same joints with anteriorly dislocated condyles. Clinical symptoms of TMJ pain, TMJ noise, or muscular pain were not found in any patients. CONCLUSIONS: Partial mandibulectomy does not affect the relationship between the disc and the condyle or the bony condition of the TMJ. The disc without a condyle will become anteriorly displaced with time. The condyle not connected to the mandibular body often dislocates anteriorly out of the glenoid fossa, while retaining a normal relationship with the disc. Joint effusion, which is detected in nonfunctional TMJs, is not associated with an inflammatory reaction in the joint compartment.

Humans↗

PubMed1992

No effect of neuromuscular blockade on the temporomandibular joint position during general anesthesia.

In an attempt to determine the role that nondepolarizing neuromuscular blocking agents play in the intraoperative position of the mandibular condyle, occlusal checkbites were taken on 10 patients under general anesthesia before and after neuromuscular blockade with vecuronium. These checkbites were compared to checkbites taken preoperatively. Nondepolarizing neuromuscular blocking agents had no effect on condylar position recordings during general anesthesia. The results demonstrate that general anesthesia itself is by far the dominant factor in intraoperative condylar position changes.

Anesthesia, General↗

PubMed2000

Analysis of the mandibular position in malocclusion patients.

OBJECTIVE: To study the changes of condyle position and occlusion between centric jaw relation (CR) and maximum intercuspation (MI) positions. METHODS: The power centric registration advocated by Roth was used to take centric relation bite registration for 50 patients (25 Angle Class I, and 25 Angle Class II). Diagnostic models were mounted and analyzed with Panadent articulator and condylar position indicator. RESULTS: Nearly all patients had CR-MI difference in all three spatial planes. Seventy percent of the sagittal displacement was within 2.0 mm and 87% of the transverse displacement was within 1.0 mm. Movement of most of the condyles was posterior and inferior. Sixty-five percent of the initial contacts in CR occurred on the most posterior molar on one side. When the mandible moved from CR to MI, overbite deepened, overjet decreased, and molar relationship became mesialized. Correlation was found between some variables of condylar displacement and occlusion changes. No significant difference between Angle Class I and Angle Class II patients was observed in condylar position and occlusion changes. CONCLUSION: The occlusion in centric jaw relation should be analyzed before treatment to reveal the disharmony between occlusion and jaw position.

Adolescent↗