Occlusion and condylar position.
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Condylar position recorded using leaf gauges and specific closure forces.
Retruded interocclusal records were made for 40 subjects after deprogramming using leaf gauges and controlled incisal forces, which were exerted on a specially constructed occlusal force sensor. These records were used to assess the resulting displacements of the mandibular condyles from their positions in centric occlusion. The leaf gauges were found not to position the condyles inferiorly and posteriorly as has been previously reported.
Adult↗
The seventh key to facial beauty and TMJ health: proper condylar position. Part 3.
This is the eleventh article in a series of articles on orthodontic diagnosis. Only a proper diagnosis can lead to the correct treatment for an individual patient--leading to a balanced profile, a beautiful smile, and a healthy TMJ. This article is to document the first phase of TMJ treatment in patients who are being treated for TMJ Dysfunction related to posterior and/or superior TMJ displacement, and the change in the mandibular position and dental relationships that almost always occurs with proper treatment. The illusion of a posterior openbite "supposedly created" by the splint has led to much misunderstanding and unhappiness with both patients and family dentists. The real "cause" of this posterior openbite and treatment procedures to correct it will be discussed.
Adult↗
[Evaluation of the condylar position in the diagnosis of temporomandibular joint dysfunction syndrome].
26 cases with Temporomandibular Joint Dysfunction Syndrome (TMJDS) were included in the present study. Fully corrected lateral tomogrames of TMJ in the intercuspid position were taken for all the cases; and fully corrected lateral arthrotomogrames were taken for 19 cases (21 joints) of them. The area and linear measurements of the joint space were made with the aid of computer. The results showed that the position of the condyle in the patients with TMJDS was located in the posterior position of the fossa. Statistics results showed that there was significant difference between the patient group and control group. Although the posterior displacement of the condyle was often associated with the anterior displacement of the disc, it was not always agreement with the anterior disc displacement. So, the exact diagnosis of disc displacement should be still on the basis of arthrography or other examinations, such as CT or MRI.
Adolescent↗
A study of the relationship between the position of the condylar head and displacement of the temporomandibular joint disk.
OBJECTIVES: To examine the possible relationship between condylar position and disk displacement in the TMJ. METHODS: Forty-eight joints with no disk displacement (NDD), 84 joints with a reducible displaced disk (RDD) and 99 joints with a permanently displaced disk (PDD) were selected. The positions of the condyle and TMJ disk were calculated from lateral MR images. RESULTS: There were significant differences in condylar position between the joints with NDD and RDD, while there was no difference between those with NDD and PDD (Kruskal-Wallis and post-hoc test, P<0.05). There was also a significant correlation between the position of the condylar and the displaced disk (Spearman's rank correlation, P<0.05). The condyle was located more anteriorly with advancing disk displacement. CONCLUSIONS: We suggest that if the disk displacement is slight, the condyle is displaced posteriorly: as the disk displacement becomes more severe (i.e. more anteriorly displaced), the condyle returns to the concentric position.
Adolescent↗
Biomechanical appraisal of some skeletal features associated with head balance and posture in the Hominoidea.
The condylar position index, condylar angle and the area of insertion of the nuchal musculature corrected for condylar position, direction of muscle pull and skull size were determined in Homo sapiens, Gorilla, Pan and the casts of two Neanderthal and two australopithecine crania. In all three attributes, the values of H. sapiens exceeded, by statistically significant amounts, those for the ape genera. The greater value for the condylar position index indicates a better balance of the head, that for the condylar angle reflects the more vertical orientation of the vertebral column while that for the corrected nuchal area suggests a less effective nuchal musculature in H. sapiens as compared to the apes. In the casts of the Neanderthal crania, the values all came within, or close to, the ranges for H. sapiens. In the australopithecine casts, the condylar angle cane within the ranges for H. sapiens while the condylar position index and the corrected nuchal area were intermediate in value between H. sapiens and the extant apes. These findings are consistent with observations from other skeletal regions that while Australopithecus had an upright posture, this creature was, in the complex of posturally significant morphological features, distinct from extant hominoids.
Animals↗
Condylar axis position, as determined by the occlusion and measured by the CPI instrument, and signs and symptoms of temporomandibular dysfunction.
The importance of occlusion as an etiologic factor in signs and symptoms of TMD has been a source of controversy. Very few studies have examined occlusion-dictated condylar position using instrumentation, and none has compared an ideal sample against an untreated control. The purpose of this study was to determine if there is a relationship between condylar axis position as determined by the occlusion and signs and symptoms of TMD, using the condylar position indicator (CPI). A sample of subjects with ideal occlusions, defined as centric relation approximating centric occlusion, was compared with a control sample of untreated subjects. The comparison was based on written patient histories, clinical exams, and CPI measurements. The ideal sample of 30 subjects was selected from a population that had undergone full-mouth reconstruction using gnathologic principles that included centric relation (CR) being coincident with centric occlusion (CO). The control group consisted of 30 untreated subjects from the general population and was matched with the ideal sample with regard to sex. A duplicate written exam was given to the subjects in the ideal sample to assess symptoms prior to treatment. The CR bite registration technique developed by Roth was used. When the pre- and posttreatment examination scores of the ideal sample were compared, an 84% reduction in symptoms was found after treatment. A high correlation (p<.001) between signs and symptoms of TMD and CPI values was documented. Since condylar axis position is dictated upon closure of the dentition into maximum intercuspation and since condylar axis position was shown in this study to be strongly correlated with TMD symptomatology, it can be concluded that a statistically significant relationship exists between occlusion-dictated condylar position and symptoms of TMD.
Adult↗
Reproducibility of the condylar reference position.
The reproducibility of the condylar reference position was examined at the pont of unstrained hinging movement of the mandible in subjects with TMJ symptoms and in asymptomatic subjects. Three different operators performed the procedure to detect interoperator variability. Each operator made five registrations using computerized axiography in the electronic mandibular position indicator mode. Data were evaluated by an analysis of variance using three factors: (1) repetitions of the single operator, (2) data from symptomatic versus asymptomatic patients, and (3) values of different operators. The results showed that none of these factors had a significant influence on reproducibility of the condylar reference position. High reproducibility was obtained in both symptomatic and asymptomatic groups. Measured values remained within +/- 0.1 mm in 58.6% and within +/- 0.2 mm in 24.3% of the registrations.
Adolescent↗
[The effect of sagittal split ramus osteotomy for advancing the mandible on temporomandibular joint].
10 patients who received sagittal split ramus osteotomy for advance the mandible were examined clinically and radiographically to assess condylar position preoperatively and six months postoperatively. The results showed after surgery maximal interincisal opening was significantly reduced; anterior, upper, posterior space of temporomandibular joint were changed; 14/20 condyles were relatively retropositioned; and 6/20 condyles were relatively forward positioned. Alteration in condylar position may undergo adjustment and remodeling in order to adapt the new position in most patients. In some patients symptoms and signs of the joint disappear following changing of condylar position.
Adult↗
Comparison of the multiphasic dysfunction profile with lateral transcranial radiographs.
Lateral transcranial radiographs of 926 patients were analyzed for condylar position, TMJ space, and obvious condylar morphologic changes. Differences in condylar position and joint space variations were noted between men and women. An increase in nonconcentric condylar position, joint space variations, and condylar morphologic changes were found with advancing age. There was a significant correlation of condylar position, joint space variations, and condylar morphology with mandibular dysfunction profile scores. Mandibular dysfunction is manifested by a wide range of signs and symptoms, none of which is always present with the disorder. Although TRs are limited in their total diagnostic value, their use in discerning major TMJ changes serves as an important adjunct in the examination and diagnosis of mandibular dysfunction.
Adolescent↗
Tomographic stability of condyle fossa relationships in 40 treated temporomandibular disorder patients.
STATEMENT OF PROBLEM: Condylar position and stability after treatment of 40 temporomandibular disorder patients was studied. PURPOSE: This study determined pretreatment position and posttreatment condylar stability. MATERIAL AND METHODS: Forty temporomandibular disorder patients with symptoms of muscles of mastication pain, temporomandibular joint sounds, attrition, interceptive occlusal contacts, and restricted range of motion were used. Axial corrected midcut sagittal tomograms were made of the 80 temporomandibular joints before treatment. Tracings from the tomograms were used to measure and analyze pretreatment position and posttreatment stability. RESULTS: Pretreatment condyle fossa position was not concentric in 26 of 80 patients (32.5%). Posttreatment condylar position showed no change and was statistically stable. CONCLUSION: In this study of 40 temporomandibular disorder patients, no statistical change in condylar position was detected. Variable condylar positions were found in the 80 pretreatment axial corrected midcut sagittal tomograms. All patients were asymptomatic after 1 year.
Adolescent↗
[Control of the condylar fragment position in interventions for sagittal osteotomy of the mandible].
The question of checking the position of the condylar fragment in sagittal osteotomy of the jaw is still controversial. The author describes an original device used by the Department of Maxillo-Facial Surgery at the University of Turin which allows precise replacing of condylar fragments. This enables a semirigid fixing of the jaw and rapid functional recovery with long-term stability of the new therapeutic position.
Equipment Design↗
[Changes of the temporomandibular joint following orthognathic surgery on radiography].
OBJECTIVE: To investigate the effect of different operative techniques and fixed methods on the TMJ condylar position and remolding process. METHODS: The standard Schuller's position radiographs were used to examine the postoperative temporomandibular joint form and condylar position changes of 57 cases within one week and one year after orthognathic surgery. The form changes were divided into three types. Type I was that the joint form was normal or abnormal before the operation and no significant change was found after the operation. Type II was that the joint form was abnormal before but after the operation it was improved. Type III was that the joint form was normal before but after the operation it changed into abnormal or it was abnormal before but after the operation it worsened. RESULTS: 1. Changes of the condylar position had happened after the operations, but within one year the condyles had resumed the same position as the preoperative. The condylar displacements were not beyond the TMJ adaptabilities. Different operative techniques had different effects on the condylar positions. 2. In 86.4% of cases, TMJs had undergone adaptable remolding (Type II) or no significant changes (Type I). Only 13.6% of cases, degenerative changes were found (Type III). CONCLUSIONS: The effect of orthognathic surgery on the condylar position and TMJ form is significant, but most of the changes are within the normal adaptability of TMJ.
Adolescent↗
[Results of an evaluation of clinical practice in orthognathic surgery in France in 2002].
BACKGROUND: Over the years, orthognathic surgery has become a mainstay of maxillofacial surgery and is the object of many publications and oral communications. However, in spite of well-established methodology, disparities still exist in France basically concerning the way orthognathic surgery is performed. MATERIALS AND METHODS: In relation with the XXXIXth congress of Stomatology and Maxillofacial surgery, a questionnaire was mailed to 100 French maxillofacial surgeons. Questions dealing with some practical points of orthognathic surgery (condylar positioning, osteosynthesis technique, rate of condylar resorption.) were asked. RESULTS: Overall reply rate was 37%. Condylar positioning was performed empirically in 73% of the cases. Mandibular osteosynthesis was achieved by titanium miniplates alone in 70%. Post-operative condylar resorption rate was about 2%. This survey produced numerous astute comments. DISCUSSION: This survey highlighted the interest of maxillofacial surgeons for practical aspects of orthognathic surgery including the questions of condylar positioning or osteosynthesis technique. These points are instrumental in achieving high-quality surgical result.
Bone Plates↗
The condyle-fossa relationship in temporomandibular disorders. Considerations on the pathogenetic role of the disc.
AIM: The purpose of this study is to evaluate the condylar position and its variation in patients with temporomandibular joint (TMJ) disorders before and after therapy with occlusal gnathologic devices. METHODS: Twenty-five TMJ of 25 patients with temporomandibular joint disorder were examined by linear measurement of the anterior, posterior and superior joint space between the condyle and glenoid fossa through cephalometric analysis on X-ray tomography of the TMJ and by calculating the condylar position with the Pullinger and Hollender method. RESULTS: The average condylar position in the TMJ with DTM was posterior with a mean value of 22.2% and a range from 14.3% to 36%. The condylar position of 25 TMJs was: anterior 0(0%); centric 8(32%) and posterior 17(68%). After therapy with occlusal gnathologic devices the average condylar position was centric with a mean value of 0.6% and a range from 5.3% to 6.6%. The condylar position of 25 TMJs was: anterior 2(8%); centric 22(88%) and posterior 1 (14%). CONCLUSIONS: The hypothesis can be advanced that joint pathology is the consequence of the alteration of the condyle position and therefore of the mandibular movement and vice versa. Therapy with occlusal devices makes it possible to modify the condylar position by increasing the condylar capability to recapture the joint disc.
Adolescent↗
Analysis of the condyle/fossa relationship before and after prosthetic rehabilitation with maxillary complete denture and mandibular removable partial denture.
STATEMENT OF PROBLEM: The influence of the loss of posterior teeth on the condylar position and on temporomandibular disorders (TMDs) remains a controversial issue. PURPOSE: This study investigated whether prosthetic rehabilitation promoted modification of the condylar position in subjects without symptoms of TMDs. MATERIAL AND METHODS: The temporomandibular joints (TMJs) of 12 women (age 37 to 74), all with existing maxillary complete dentures but no removable partial denture (RPD) restoring the Kennedy class I partially edentulous mandibular arch and no clinical signs of TMDs according to the criteria established by Helkimo, were viewed in maximal intercuspal position with corrected lateral tomography before and after prosthetic rehabilitation with a new maxillary complete denture and a mandibular RPD. Before prosthetic rehabilitation, a mandibular stabilizing base was fabricated to prevent the existing maxillary complete denture from dislodging during tomographic examination. Two methods were used to evaluate tomograms: (1) linear measurements of the subjective narrowest anterior and posterior intra-articular joint spaces made from the tomograms by use of a digital caliper and (2) linear measurements of the anterior and posterior intra-articular joint spaces on the basis of drawings and tracings. Repeated-measures analysis of variance followed by orthogonal contrasts were used to evaluate differences between measurements carried out on the same subject under the different test conditions of the study (before prosthetic rehabilitation, before prosthetic rehabilitation with a mandibular stabilizing base in position, and after prosthetic rehabilitation) (P<.05). RESULTS: Before prosthetic rehabilitation, a predominance of posterior condylar positions was observed. Before prosthetic rehabilitation with a mandibular stabilizing base in position, a significant decrease was observed in posterior condylar positions (P=.03). This decrease was more marked after prosthetic rehabilitation (P=.02). The subjective evaluation and comparison on the basis of drawings and tracings used to analyze the tomograms produced similar results (P=.70). CONCLUSION: Within the limitations of this study, significant changes in the condylar position occurred after prosthetic rehabilitation in subjects without symptoms of TMDs.
Adult↗
Proximal segment positioning in bilateral sagittal split osteotomy: intraoperative dynamic positioning and monitoring by sonography.
PURPOSE: Most methods of condylar positioning merely maintain the preoperative condyle-fossa relationship and therefore produce similar prevalences of postoperative dysfunction. This study evaluates dynamic proximal segment positioning by intraoperative sonography versus the splint and plate technique discussed in a previous issue. PATIENTS AND METHODS: Condylar positioning was monitored by sonography alone in 30 bimaxillary operated patients (14 Angle Class II, 16 Class III), the control group had a splint and plate positioning in 23 patients (9 Angle Class II, 14 Class III). The clinical dysfunction index, prevalence of condylar translation, and disc dislocation were compared preoperatively and at 1, 6, and 12 months postoperatively. RESULTS: The postoperative range of motion did not disclose statistically significant differences between study and control group (Pearson's proportionality index r = 0.78, 2-way analysis of variance: P <.4, F = 4.4, alpha =.05 significance level). Sonographic placement allowed dynamic intraoperative monitoring of the condylar position and required an average of 5 minutes compared with 25 minutes for conventional positioning. Postoperative dysfunction prevalence was reduced 89% for Class II and 100% in Class III in the study group versus 50% for Class II and 100% for Class III in the control group (r = 0.45, P <.3, F = 9.3). Prevalence of disc dislocation was reduced 76% in Class II and 80% in Class III patients in the study group and 50% of Class II and 100% of Class III in the control group (r = 0.7, P <.48, F = 9.2). CONCLUSIONS: Comparable postoperative reduction of condylar translation and recovery, dysfunction, and disc dislocation was seen with use of both methods in a 1-year follow-up. The new technique allowed intraoperative real-time monitoring and dynamic correction and was safe, easier, and faster than conventional plate positioning.
Adolescent↗
Modelling of forces in the human masticatory system with optimization of the angulations of the joint loads.
Numerical models of the human masticatory system were constructed using algorithms which minimized non-linear functions of the muscle forces or the joint loads. However, the predicted solutions for isometric biting were critically dependent upon the modelled angular freedom of the joint loads. The most complete mathematical minimization of any objective function occurs when the joint load angles are predicted. However, the predictions have to be sensible in relation to the actual morphology of the joints. Therefore, the models were tested in terms of the angles of joint load predicted for a dry skull, using muscle vectors reconstructed from the geometry of the skull. The minimizations of muscle force were intrinsically incapable of predicting the angles of joint load. Such models must rely on constrained angles and this produces a restricted minimization and also an indeterminacy. In contrast, the minimizations of joint load predicted angles of joint load which varied appropriately with condylar position. The condylar movement was achieved with a positioning model which adjusted the angulation of the muscle vectors as the jaw was positioned. This model also generated the optimal sagittal shape of the articular eminence. Muscle predictions from the various models were not examined in detail, but the general nature of the predicted muscle force patterns was shown to be reasonable in some of the models and unreasonable in others. The results supported the hypothesis that the temporomandibular joint develops functionally to allow an approximate minimization of the joint loads during isomeric biting. This does not necessarily imply that the neurophysiological control is actually based on a minimization of joint load.
Algorithms↗