替牙期骨性Ⅲ类错牙合患者颞下颌关节特征的锥形束CT研究

目的:采用锥形束CT(CBCT)研究替牙期骨性Ⅲ类错牙合患者颞下颌关节的影像学特征,探讨Ⅲ类功能状态下,颞下颌关节的生长、改建机制。方法:从就诊于昆明医科大学附属口腔医院正畸科的患者中选取符合纳入标准的替牙期骨性Ⅲ类错牙合患者及骨性Ⅰ类错牙合患者各20名,使用NNT viewer 5.3图像处理软件进行三维重建及线距和角度的测量,并进行统计学分析。结果:替牙期骨性Ⅲ类错牙合患者组和替牙期骨性Ⅰ类错牙合患者组对比结果为:矢状面双侧关节前间隙偏小、双侧关节上间隙偏小、双侧关节结节斜度偏小;冠状面双侧关节内间隙偏小,双侧关节上间隙偏小,双侧关节外间隙偏小,右侧髁状突角度偏小;横截面右侧髁状突前后径偏小。结论:替牙期骨性Ⅲ类错牙合患者颞下颌关节发育不充分,呈现髁状突,关节窝深度,关节结节斜度;冠状面关节内、外间隙均较小的特征。骨性Ⅲ类错牙合患者髁状突在关节窝中处于前置近关节窝顶位置。骨性Ⅲ类错牙合患者颞下颌关节影像学特征与其功能状态相适应。     

Observations on Individuals with Radiographic Bilateral Condylar Remodeling

Clinical, panoramic, cephalometric, and arthrographic findings are presented for 29 patients with bilateral condylar remodeling. Questions are raised with regard to joint noise and limited opening as indicators of intracapsular pathology and to a potential additive effect of condylar remodeling on the severity of Class II malocclusions that exist in individuals with condylar remodeling. It is postulated and supported that certain typical changes in condylar morphology, previously described but unexplained, are the result of chronic anterior dislocation of the meniscus without reduction, and that centric occlusion-centric relation discrepancies may be the result of condylar remodeling in some TMJ patients. The value of arthrographic examination in diagnosis is supported.     

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.     

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.     

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.     

A follow-up study of condyle fracture in children

This paper reports a long-term clinical and radiological evaluation of conservatively treated condylar fractures in children. The long-term effects of treating condylar fractures in children with non-surgical therapy were examined in order to resolve the controversial question ‘Does complete remodeling occurs at this age or, if not, is it more likely to be associated with certain types of fractures or other factors?’This study was based on a series of 11 consecutive children and adolescents, aged between 3 and 15 years, with fractures of the condylar process who had been treated with conservative therapy.All patients underwent a clinical investigation with a special emphasis on the temporomandibular joint function and facial asymmetry. The patients also underwent a radiological investigation, focusing on the fracture remodeling and symmetry of the mandible, which consisted of a panoramic radiograph, PA and a lateral cephalogram and 3-D CT.No patient complained of an impaired temporomandibular joint (TMJ) function or pain on the affected side. Two out of eight (25%) unilateral and one bilateral fracture show a slight facial asymmetry. Despite the apparent excellent recovery of function, there were marked remodeling changes evident on the CT scan. Such changes are not usually evident on a panoramic radiograph. The radiological investigation showed an incomplete remodeling (six patients, 54.5%) and an asymmetry of the mandible (three patients, 27.3%) in some patients.Non-surgical treatment of condylar fractures in children results in the satisfactory long-term outcome of the jaw function despite the relative high frequency of radiologically noted aberrations.     

A Tomographic Study of the Condyle/Fossa Relationship in Patients with TMJ Dysfunction

The authors undertook a tomographic study to evaluate the positional relationship of the bony components of the temporomandibular articulation. The sample group consisted of 35 patients with symptoms involving the temporomandibular joint. These were compared to a control group of 19 asymptomatic subjects who had “normal” occlusions. The condylar positions of the symptomatic and the asymptomatic TMJs of the sample group were compared with each other and with those of the control group.

Each of the subjects gave a complete dental history and underwent thorough intra- and extraoral examination. The authors used a submental vertex radiograph to determine the center of each condyle and the horizontal condylar angulation for each subject. The two values obtained from this were used to take a selective tomogram, in centric relation, of the condyles of all the subjects. An anterior prosthesis was used to obtain centric relation in each case.

The tomograms obtained from these subjects were enlarged ten times. Tracings and measurements were made of the enlarged images, and the measurements obtained were reduced by a factor of ten for recording. The authors then evaluated the position of the condyle within the glenoid fossa by comparing joint space measurements and by using a proportional analysis.     

Temporomandibular joint remodeling in adolescents and young adults during Herbst treatment: A prospective longitudinal magnetic resonance imaging and cephalometric radiographic investigation

The aim of this prospective study was to analyze and compare the temporomandibular joint adaptive mechanisms in 25 adolescent and 14 young adult Class II malocclusions treated with the Herbst appliance. Temporomandibular joint remodeling was analyzed by magnetic resonance imaging. In each subject, 4 magnetic resonance images of both temporomandibular joints were available: before treatment, at the start of treatment (when the Herbst appliance was placed), during treatment (6 to 12 weeks after appliance placement), and after treatment (when the appliance was removed). Furthermore, effective temporomandibular joint changes (the sum of condylar remodeling, fossa remodeling, and condyle-fossa relationship changes) were analyzed with the aid of lateral cephalometric radiographs from before and after treatment. All subjects were treated to Class I or overcorrected Class I dental arch relationships, and their mandibles became significantly (P <.001) more prognathic. After 6 to 12 weeks of Herbst treatment, signs of condylar remodeling were seen at the posterosuperior border in 48 of the 50 adolescent condyles and in 26 of the 28 young adult condyles. Bilateral remodeling of the mandibular ramus could be detected in 1 adolescent and 2 young adult patients. Signs of glenoid fossa remodeling at the anterior surface of the postglenoid spine were noted in 36 adolescent and 22 young adult temporomandibular joints. Effective temporomandibular joint changes during treatment were more horizontally directed and larger in both adolescents and young adult patients treated with the Herbst appliance than in an untreated group of subjects with ideal occlusion (Bolton standards). The increase in mandibular prognathism accomplished by Herbst therapy in both adolescents and young adults seems, in particular, to be a result of condylar and glenoid fossa remodeling. Because the Herbst appliance is most successful in Class II patients also at the end of the growth period, the treatment method could be an alternative to orthognathic surgery in borderline skeletal Class II cases. Magnetic resonance imaging renders an excellent opportunity to visualize the temporomandibular joint remodeling growth processes.     

An evaluation of horizontal jaw relations during standing and sitting with open or closed eyes

When determining the horizontal jaw relation and mandibular movements, a question arises as to the appropriate choice of registration positions. The current study was carried out using 22 adults with full dentition who did not have any discomfort in their skeletal and craniomandibular systems. Occlusion and mandibular movements were investigated with open and closed eyes in standing and sitting positions using an electronic, central-bearing tracing device. The coordinates of the measured parameters are presented using a two-dimensional computer vector diagram. The non-parametric Friedman test was used for statistical data analysis. The measured data obtained for the initial habitual centric relation record (HR), centric relation record (CR), final habitual centric relation record (HR), and protrusion (P) did not significantly differ in the sitting and standing positions or with opened and closed eyes (p = 1.00). With closed eyes, the differences in the average values between the two condylar positions (initial HR/final HR, initial HR/CR, and final HR/CR) decreased in a manner that was independent of the registration position. The CR that was measured in a sitting position with closed eyes was 2.26 mm more retrusive than that measured with open eyes. Before and after CR measurements, only laterotrusion showed significant differences (p=0.02) in patients who were standing with closed eyes. It was concluded that the registration position and visual system could individually influence the measurements of condylar position and mandibular movements. From a clinical perspective, these measurements exhibited the smallest differences when they were conducted with patients in a sitting position with closed eyes.     

A Comparative Evaluation of Static and Functional Methods for Recording Centric Relation and Condylar Guidance: A Clinical Study

To evaluate and compare the centric relation and horizontal condylar guidance using interocclusal wax and extra oral Gothic arch methods and subjective evaluation of dentures thus fabricated. Centric relation and horizontal condylar guidance was recorded by using interocclusal wax and gothic arch tracing in 28 completely edentulous patients. These records were transferred to the articulator and difference in both values was recorded. After that patients were divided in two groups according to the centric relation and horizontal condylar guidance recording method used to achieve balanced occlusion. Response of the dentures was subjectively evaluated using “Woelfel subjective evaluation criteria”. Centric relation recorded by both the methods did coincide in 7.14 % of patients. Centric relation recorded by interocclusal wax was posterior to Gothic centric relation in 21.43 % of patients, and anterior to Gothic centric relation in 71.42 % patients. Gothic arch tracings gave higher mean guidance values on both the sides as compared to protrusive wax record in all the subjects, although the difference was statistically insignificant (P > 0.05). Subjective evaluation showed statistical insignificance for all the parameters in both groups. Gothic arch method records the centric relation at a more posterior position than the Static method, but it does not make any difference in clinical performance of the complete denture. Horizontal condylar guidance angle was approximately similar by both the methods.     

Analysis of Condylar Differences in Functional Unilateral Posterior Crossbite during Early Treatment – a Randomized Clinical Study

OBJECTIVE: The analysis of potential discrepancies in condyle position among different occlusal relations (centric relation and maximum intercuspidation) is a key diagnostic component when treating children with unilateral posterior crossbite. Due to strict requirements imposed by ethics committees, and new regulations regarding the use of X-rays, radiological examinations (axial cephalometric radiographs or postero-anterior cephalometric radiographs) are not feasible. Thus the aim of this study was to apply an alternative procedure for the assessment of condylar deviations. PROBANDS AND METHODS: : We employed ARCUS digma, a measuring system based on ultrasound technology, to record condylar differences occurring in 65 children (6.9+/-2.0 years of age) with functional unilateral posterior crossbite in late deciduous and early mixed dentition. After randomization, 31 patients underwent early orthodontic treatment (bonded palatal expansion appliance and U-bow activator), whereas 34 patients remained untreated. Examinations were carried out at the beginning (T1) and after 12 months of treatment (T2). A three-dimensional (3D) assessment of deviations between maximum intercuspidation and centric position was carried out. Statistical analysis was performed using the SPSS 12.0 software program. RESULTS: Initially, the electronic position analysis revealed no significant differences between the control and therapy groups. A mean condylar deviation of > 2 mm was noted at T1 in the sagittal, frontal and transversal planes for crossbite and the noncrossbite sides. This difference was reduced in the therapy group, a finding that proved statistically highly significant (p<0.001). We also observed a highly significant (p<0.001) difference between the control and therapy groups at T2. CONCLUSION: The Münster concept for early treatment of functional unilateral posterior crossbites in late deciduous and early mixed dentition significantly improved the treated patients' occlusion in comparison to a randomized control group, which exhibited no spontaneous self-healing tendencies.     

Posterior unilateral condylar displacement: its diagnosis and treatment.

The treatment procedure for posterior unilateral condylar displacement has been described. An acrylic resin repositioning prosthesis may be used to decrease trismus. Occlusal adjustment permits lateral freedom for mandibular movement to the opposite side which provides a dual, or a therapeutic, centric occlusion as well as the existing dysfunctional centric relation. This permits the patient's physiologic adaptive mechanism to choose between the existing dysfunctional centric relation, which resulted in unilateral condylar retrusion and pain, or a therapeutic centric occlusion which is aimed at anterior unilateral condylar repositioning. Over long period of time, muscle reprogramming produces maximum intercuspation of teeth in the planned therapeutic centric occlusion rather than in the original dysfunctional position. No explanation has been established for this phenomenon. It is important, however, to provide a technique that permits physiologic adaptability over a period of time. It should be emphasized that this is not TMJ "remodeling" but a functional change in the position of the jaw. The treatment objectives of bilateral and unilateral posterior condylar displacement are similar, but the clinical techniques are completely different. In either instance, TMJ radiographs are necessary to establish the diagnosis and treatment, as well as to document the postoperative results.     

Practical evaluation of the lateral temporomandibular joint radiograph

The reevaluation of the lateral transcranial radiograph is needed because of the confusion that surrounds the diagnosis and treatment of TMJ dysfunction-pain. The lack of universal acceptance of the validity of the lateral TMJ radiograph contributes to the lack of progress of TMJ dysfunction-pain treatment and improved methods for the treatment of prosthodontic patients. The lateral transcranial TMJ radiograph was reevaluated for its duplicability (+/- 0.2 mm). The image was found to be a cross section of the lateral third of the condyle rather than a composite view of the condyle made at an angle. The condylar position in the fossa can be correctly evaluated in transcranial radiographs, because the relative condylar position in the fossa is similar in all sagittal views and the image is always of the same sagittal plane (lateral third). Soft tissue within or lining the fossa does not affect the evaluation of condylar position. Chronic osteoarthritic TMJ pathology can exist without subjective pain; therefore, routine use of initial TMJ radiographs with subsequent radiographs at 5-year intervals is suggested for all patients. Because condylar repositioning may be indicated before subjective pain symptoms appear, condylar repositioning should be contemplated whenever extensive prosthodontic treatment is needed. In addition, if chronic osteoarthritic lesions are observed initially, radiographs are indicated at more frequent intervals and anti-inflammatory agents should be considered for routine use depending on the rate and extent of the pathologic development. The existence of osteoarthritic lesions was confirmed by serial radiographs over 5 to 10 years. If an osteoarthritis is present, condylar repositioning (when condylar displacement is present) or changes in occlusion should be considered. There is some clinical evidence that condylar displacement is associated with pathologic remodeling and/or osteoarthritic lesions of the condyle and that condyle repositioning arrests the pathologic process. The principle of condylar concentricity , previously established for the treatment of TMJ dysfunction-pain syndrome and for functional centric relation in prosthodontics, was formulated by associating condylar position in the fossa with TMJ dysfunction-pain in many patients. This article suggests the value of the lateral TMJ radiograph as an important practical aid in the diagnosis and treatment of TMJ dysfunction pain and in the establishment of functional centric relation in prosthodontics.     

髁突在关节窝中的位置及其在临床诊断治疗中的意义

临床治疗中,特别是髁突外伤骨折、正颌手术、修复咬合重建、正畸治疗以及在颞下颌关节紊乱病的诊断和治疗中,要考虑髁突在关节窝中的位置变化。本文通过文献回顾,结合我们的研究成果,讨论髁突在关节窝中的正常生理位置及其在颞下颌关节紊乱病特别是关节盘移位的诊断和治疗中的意义。目前多项研究认为,健康成年人髁突平均位置为基本中性,但存在较大变异;髁突后移可能是关节盘前移位的危险因素,关节盘前移位也可导致髁突后移;在关节盘移位的牙合垫治疗中,髁突在牙合垫戴入后显著向前、下移位,可有效改善盘突关系;稳定牙合垫使髁突前下移位不明显,改善盘突关系的效果有限。此外,再定位牙合垫使髁突前下移位还可促进髁突骨质的改建。     

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.     

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??Abstract??The condylar position should be taken into account in the diagnosis and treatment of condyle fracture??orthognathic surgery??occlusal reconstruction and temporomandibular disorders. The normal condylar position in the glenoid fossa and its clinical significance in the diagnosis and treatment of temporomandibular disorders??for example the disc displacement??will be discussed here through the literature review and the combination of our research findings. Many research data suggested a centric position of condyle in a normal joint??with individually variances. A posterior condylar position might be a risk factor of disc displacement??and on the other hand??the disc displacement might induce condyle to move posteriorly. With the use of anterior repositioning splint for treating anterior disc displacement with reduction??the condyle moved anteriorly and inferiorly??the condyle-disc relationship could be improved immediately. Besides??splint therapy may facilitate regenerative remodeling of condyles.     

The effects of unilateral discectomy and condylectomy on the contralateral intact rabbit craniomandibular joint.

PURPOSE: The purpose of this study is to determine the effects of unilateral discectomy and condylectomy on the contralateral intact rabbit craniomandibular joint at the histological level. MATERIALS AND METHODS: Fifteen New Zealand white rabbits were used and divided into 3 groups. Three rabbits were used as controls (group A) whereby a sham operation was undertaken without breaching the joint space of the left craniomandibular joint (CMJ). In 6 rabbits (group B), the articular disc of the left CMJ was excised. The remaining 6 rabbits (group C) underwent surgical resection of the left condylar head at the level of the condylar neck. The resultant surgical defects were left to heal without any grafting and the incisions were closed with resorbable sutures. The rabbits were sacrificed at 4, 12, and 20 weeks after surgery and both the left and right CMJs were histologically prepared and examined under light microscopy. RESULTS: In the 4-week group, unilateral discectomy and condylectomy resulted in remodeling of the unoperated right CMJ with histological evidence of flattening of the condylar head which was more pronounced in the condylectomy group. In the 12-week group, the remodeling process in the unoperated right CMJ was less pronounced with most of the activity concentrated in the medial pole, especially in the condylectomy group. The 20-week group showed no obvious signs of remodeling in the unoperated right CMJs in both the discectomy and condylectomy groups. Evidence of condylar regeneration was seen in all groups in the left CMJ which had undergone condylectomy. No evidence of disc regeneration in the operated left CMJ was seen in any of the discectomy groups. CONCLUSIONS: Unilateral discectomy and condylectomy have an early adverse effect on the structural integrity of the contralateral unoperated CMJ which appears to be short lived. The early remodeling effects on the unoperated right CMJ appear to be reversible as the operated left CMJ heals.     

Conservative treatment of unilateral condylar fractures in children: a long-term clinical and radiologic follow-up of 55 patients

The purpose of this prospectively designed study was the long-term clinical and radiological evaluation of conservatively treated unilateral condylar fractures in children. Fifty-five children aged between 2 1/2 and 9 3/4 years, presenting with a singular unilateral fracture of the mandibular condyle, were treated in a nonsurgical-functional way using an intraoral myofunctional appliance. In the follow-up period, patients were investigated by standardized clinical examination and by evaluation of panoramic radiographs taken immediately post-traumatically, after 6, 12, 24, 48 and 72 weeks, and then yearly through the period of growth. With a satisfactory clinical course in all patients, there was no instance of functional disturbance or mandibular asymmetry after the respective follow-up periods. The radiographs showed a fairly good shape of the condyle (no or only slight condylar deformity) in the 47 patients of the 2-6 year age group. In the eight patients of the 7-10 year age group presenting with a class II or III condylar fracture, healing was characterized by incomplete condylar regeneration, resulting in a moderate condylar deformity in two cases, a definite reduction in condylar neck height in two cases, and a hypertrophic condylar deformity in four cases. The positive results of this study confirm the concept of a nonsurgical-functional approach in children presenting with various types of unilateral fractures of the mandibular condyle. Condylar remodeling was the mode of fracture healing in instances of displaced and dislocated condylar fractures.     

Posterior bilateral condylar displacement: its diagnosis and treatment.

One type of condylar displacement (posterior bilateral) was discussed as an etiologic factor in TMJ dysfunction. Joint noise, tenderness on muscle palpation, and acute TMJ pain are all considered signs of TMJ dysfunction. Any joint noise is considered to be an early dysfunctional symptom because of its higher incidence in association with palpable muscle pain or acute TMJ dysfunction. Sometimes the joint noise will immediately precede acute muscle pain and/or fluctuate with the painful symptoms. The treatment of bilateral posterior condyle displacement has been described. The mandibular anterior teeth were shortened and the maxillary posterior occlusion adjusted so that the mandible could be respositioned in an anterior position without increasing the vertical dimension of occlusion. A silver-plated maxillary cast was obtained and mounted on a semiadjustable articulator (Hanau) with a face-bow. The mandibular cast was mounted in the dysfunctional (retruded) centric relation. The articulator was moved into a protrusive position by the amount of anterior correction that is needed to reposition the condyles into the middle of the fossae symmetrically on both sides. The original TMJ radiographs provide the necessary information for this clinical judgment. Acrylic resin was placed in the space created between the condylar sphere and stop on the articulator. An acrylic resin temporary repositioning prosthesis constructed on the metal cast has two functions. It provides a therapeutic trial for the anterior condylar respositioning, and it holds the mandible in the therapeutic position while TMJ radiographs confirm the corrective position of the condyles in the fossae. After a successful 6 to 8 week trial period with remission of symptoms, a gold prosthesis was constructed on the same cast in the same therapeutic position. It remains to be seen whether, after several years, the condylar suspension system changes from a dysfunctional centric relation to a new functional centric relation in which the patient can no longer return to the posterior displaced condylar position in the fossa. Only with painstaking observations, accurate TMJ radiographs, complete documentation, and after-care can a more scientific approach to the diagnosis and treatment of TMJ dysfunctional pain syndrome be achieved.     

Computed tomography of condylar and articular disk positions within the temporomandibular joint

The computed tomograms of temporomandibular joints in 25 patients (41 joints) were retrospectively evaluated for condylar position and joint space with General Electric computer software. Computed tomography scans of the temporomandibular joint were made in the axial plane with the teeth in centric occlusion, and measurements were made from vertically reformatted images. Interarticular joint spaces were measured anterosuperiorly, superiorly, posterosuperiorly, and posteriorly from the condylar surfaces. This was repeated in five equidistant (3.1 mm) serial sagittal planes across the condyle, beginning and ending, on average, 2.5 mm from the lateral and medial condylar poles. Articular disk positions (anterolateral, anterior, anteromedial, medial, and normal) were correlated with condylar position. Significant differences between disk positions and joint spaces were found most frequently in the anterosuperior and the superior joint interval. When the disk was positioned normally, the anterosuperior joint space was consistent (1.5 to 2.0 mm) across the joint (standard deviation, 0.3 to 0.8 mm). The superior, the posterosuperior, and the posterior joint spaces in the normal joint were greater than the anterosuperior joint space. When the disk was anterior to the condyle, the anterosuperior joint interval was widened. When the disk was medial, the superior joint space was significantly wider than normal across the breadth of the condyle. In those joints in which the disk was anteromedial, there was an absence (0.2 mm) of joint space, and this occurred in all areas of the condyle except in its medial one fourth. In the internally deranged joint, joint space narrowing may be focal in nature.