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PubMed1996

Effects of fixed anterior biteplane therapy--a radiographic study.

Orthodontic treatment of eight overbite cases with a maxillary fixed lingual arch appliance with anterior biteplane involved a reduction in overbite of 4 to 7 mm between the upper and the lower front teeth and a first molar separation of 2 to 4 mm. After a treatment period of 3.5 to 5 months, occlusal contact between the upper and the lower molars was established. The appliance was then removed, and permanent overbite reduction was secured with an edgewise appliance. With the subtraction technique, 15 temporomandibular joints were radiographically investigated in the retruded position for change of condylar position on the glenoid fossa before and directly after insertion of the appliance, as well as after achieved molar contact. All condyles changed position directly after the bite opening, indicating that pure rotation did not occur. The direction of movement varied not only between subjects but also between the two condyles of each subject. With one exception, none or very small further positional changes occurred during treatment. No imaged signs of hard structure remodeling were observed. It may be concluded that other factors than change of condylar position must be responsible for the therapeutic effect of the bite-opening appliance that has been demonstrated in an earlier study.

Adolescent↗

PubMed1984

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.

Cartilage, Articular↗

PubMed1989

Quantitative and subjective analysis of temporomandibular joint radiographs.

The lateral oblique transcranial radiograph of the temporomandibular joint is commonly used in dentistry. Changes in horizontal angulation of the x-ray beam can produce changes in radiographic condylar position. This study used quantitative and subjective methods to assess and rank changes in radiographic condylar position as a function of known horizontal x-ray beam changes. Six dry skulls were positioned in a craniostat device where known angulations could be measured. Nine sequential transcranial temporomandibular joint radiographs were made of each joint and five of these 12 sets were randomly selected for analyses. The quantitative method involved film digitization, computer calculations, and expressed condylar position as a ratio between posterior and anterior joint space distributions. Eight observers viewed the same films and ranked radiographic condylar position from anterior to posterior. The two methods agreed with known rankings 81.8% of the time. Subjective rankings were more variable than quantitative rankings. Intraobserver differences were insignificant and the observers were consistent among themselves as a group.

Cephalometry↗

PubMed1991

Validity of digital subtraction of transcranial plain films in quantification of positional changes of the mandibular condyle.

Condylar positioning problems have been associated with temporomandibular joint signs and symptoms. The position of the mandibular condyle is difficult to predict and quantify with existing routinely used radiographic techniques. An investigation was implemented to test the validity and reliability of digital subtraction to enhance transcranial plain films and to quantify positional changes of the condyle in a laboratory model. The model consisted of a mounted dried human skull and a mandibular condyle attached to a micromanipulator. Controlled changes in condylar position were made, and the condyle and fossa were imaged. The data were analyzed with descriptive statistics, analyses of variance to evaluate the sources of variability, and linear contrasts to evaluate the differences between observed and expected values. The results indicated that digital subtraction detected posterior positional change within 10% of the expected value. However, inferior positional changes were poorly detected and lateral positional changes could not be evaluated by this technique. We conclude that digitally subtracted transcranial radiographs may be useful for detection of posterior condylar movements, assuming that appropriate head-holding devices are used to fix x-ray source and head geometry.

Analysis of Variance↗

PubMed1997

Maintenance of the preoperative condyle position in orthognathic surgery.

A bimaxillary osteotomy for mandibular prognathism and maxillary retrognathia was performed on 30 patients with an Angle Class III malocclusion. The Luhr condylar positioning device was used intraoperatively to reproduce the condylar position. Pre- and postoperative condylar positions were compared by recording joint movements with axiography. Steps, jags and jumps as symptoms of pathological joint function could not be identified. Only in one case could a pathological shortening of the joint track length be measured. This suggests that the Luhr device is effective in securing condyle position and therefore temporomandibular joint (TMJ) function. Pre- and postoperative axiography is an adequate method of controlling these results and a helpful supplement to the armentarium of orthognathic surgery.

Dental Articulators↗

PubMed1986

Condylar retruded contact position and intercuspal position correlation in dentulous patients. Part I: Three-dimensional analysis of condylar registrations.

A three-dimensional condylar analysis of the ICP relative to the RCP was completed for 75 patients by using a system of styli adapted to an arcon articulator. The recorded sagittal condylar positions were seen in three of the four quadrants, the posterior-superior quadrant was devoid of registrations. The percent of registration was approximately equal for the right and left sides; anterior-inferior quadrant, 60%; posterior-inferior quadrant, 30%; and anterior-superior quadrant, 10%. Midcondylar value of the ICP presented the smallest standard deviation but the data concerning condylar position were unreliable because symmetrical and asymmetrical movement may produce similar midcondylar values. Seventy-two percent of the anterior-posterior and 45% of the superior-inferior condylar ICP recordings of patients fell within the range of a dentally healthy sample of young men. Only 2% of recordings the patients were outside this range in a superior direction. These data were nearly equal numerically for the right and left sides and conformed to the anatomic freedom of TMJ. Slightly more than 57% of the sample had an MLD greater than 0.3 mm compared with a dentally healthy sample. There was a 42% greater incidence of skew greater than 0.7 mm and a 22% greater occurrence of tilt greater than 0.7 mm in the dental patient sample, compared with the findings of Hoffman et al. An index ICP asymmetry was proposed that indicates the relative value of skew and tilt in a single quantitative factor. Three mandibular movements were identified, skew and tilt with angular components and MLD, translation. These three movements have 3 degrees of freedom, right or left movement or no movement, resulting in 27 permutations. The combination of these elements make it difficult to determine condylar position from occlusal midline observation.

Adult↗

PubMed2007

Intraoperative awakening of the patient during orthognathic surgery: a method to prevent the condylar sag.

PURPOSE: The intraoperative diagnosis, during orthognathic procedures, of an unfavorable condylar position is highly desirable. A simple technique that can reliably identify a malpositioned condyle intraoperatively has obvious advantages. The manual positioning of the condyle is easier, but it requires the utmost care and an experienced operator. Muscle tone is described as maintaining contact across the temporomandibular joint. The anesthetized and curarized patient has a condylar position posterior to that in the same patient when he is awake, with the same seating force applied. Under general anesthesia, the condyle may be inferior and might not feel stable until it moves posteriorly and has adequate compression of the retrodiscal tissues on the posterior wall. Relapse of the occlusion as a result of changes in the condylar position may occur immediately after the removal of the temporary intermaxillary fixation (IMF). The surgeon needs to understand the mechanism of condylar sag and the specific patterns of malocclusion that it may produce. This will enable him to make a diagnosis and to implement the appropriate corrective measures, providing the opportunity for immediate correction of condylar position, thereby obviating the need for a second operation or orthodontic compromise. MATERIALS AND METHODS: A study group (group A, 76 patients) and a control group (group B, 73 patients) were randomly formed from the dysgnathic patients scheduled for bimaxillary orthognathic surgery (Le Fort I osteotomy and bilateral sagittal split osteotomy). The free mandibular proximal segment was gently and manually positioned in the glenoid fossa. All the mandibles were fixed with bicortical screws. In group A, immediately after the fixation, IMFs were removed and the occlusions were checked with light digital pressure on the chin, then the patients were rapidly awakened (maintaining the intubation) in a state of conscious analgo-sedation and asked to open and close, and to laterally move the mandible. If clinical examination of the passive and active movements of the mandible was suitable, the anesthesia was reinforced and the operation was concluded. RESULTS: In 11 of the 76 patients of group A, malocclusion was noted, after the rigid fixation, with the method of digital pressure on the chin; the intraoperative awakening of the patients confirmed the clinical appearance and it provided further clinical signs to identify the offending condyle and to favor appropriate corrections. In 8 of the group A patients, malocclusions were not noted with manipulation of the mandible, but they were pointed out during the intraoperative awakening, and then they were appropriately corrected. In 2 of the group B patients, malocclusion was noted, after the rigid fixation, with the method of digital pressure on the chin, and it was immediately corrected. In 7 of the group B patients, malocclusion was not noted during the operation with the method of digital pressure on the chin, but it was noted at the end of the surgical procedure (12-24 hours after). CONCLUSION: Muscle tone, muscular activity, and proprioception appear to have important roles in the clinical evidence of a postoperative malocclusion during the intraoperative awakening; they can reliably implement the accuracy of the diagnosis of condylar sag, and they can favor its correction.

Adolescent↗

PubMed1998

[Biomechanical analysis of occlusal splint therapy].

OBJECTIVE: The changes of the location and force of the condyle influenced by occlusal splint were investigated in order to know the biomechanical mechanism of occlusal splint therapy. METHODS: Auto-CAD technology, CT scanning, computer imaging analysis measurement and finite element method were separately used to comparatively analyze condylar position and its stress distribution in patients with temporomandibular joint disorders (TMD) treated with or without occlusal splint. RESULTS: Occlusal splint could lessen anterior space, in crease posterior and upper space in the temporomandibular joint (TMJ), so the condylar position move anterioinferiorly; the stress on condylar surface was lowered, mainly in anterior oblique surface or lateral side of condylar loading position; and the stress symmetry was bilaterally improved. OCCLUSION: The study suggests that regulating condylar position and improving the stress distribution is considered one of biomechanical mechanism of occlusal splint treatment.

Adult↗

PubMed1994

An analysis of surface congruity in the growing human temporomandibular joint.

The influence of condylar position on congruity of the surfaces of the temporomandibular joint (TMJ) was determined. The degree of congruity between the loading surfaces of the condyle and the eminence varied depending on condylar position. Better congruity of surfaces was found in condylar positions consistent with molar biting. Incongruity between surfaces occurred more frequently at the crest of the TMJ eminence and was related to the degree of eminence development. The evidence supports an hypothesis that growth of the TMJ eminence creates incongruities between loading surfaces that predispose to stress concentrations in the anterior regions of the articular surfaces. The findings may help to explain why degenerative lesions commonly occur at the crest of the eminence.

Adolescent↗

PubMed2003

Indications to the use of condylar repositioning devices in the surgical treatment of dental-skeletal class III.

PURPOSE: The aim of this report was to compare the clinical and radiographic findings observed at the 12-month follow-up in 2 groups of 15 patients who underwent Le Fort I and bilateral sagittal split osteotomy for the correction of dental-skeletal Class III. In the first group, the condylar positioning devices were used, whereas in the second group, an alternative method was used for the intraoperative assessment of mandibular repositioning. MATERIALS AND METHODS: All of the patients of our study in the immediate presurgical period were without temporomandibular joint disorders and with a normal anatomic relationship between condyle and fossae. The condyle position and morphology were examined at the 12-month follow-up through cephalometric measurements and the postsurgical findings in both groups were compared with those observed in the presurgical period. RESULTS: In all of the 30 patients in our study, no relapse or postsurgical temporomandibular joint disturbance was observed at the 12-month follow-up. Variations in condyle position of more than 2 mm or 2 degrees were not observed in the 15 patients treated with condylar positioning devices. Changes in condyle position between 2 and 4 mm and 2 degrees and 4 degrees were observed in 6 of the 15 patients treated without the devices. CONCLUSIONS: The use of condylar positioning devices can be avoided in patients with dental-skeletal Class III without presurgical temporomandibular dysfunction. The manual positioning of the mandibular condyle is easier, but it requires the utmost care and an experienced operator.

Adult↗

PubMed1991

Perceptibility of condylar displacement through transcranial radiographs and split-cast technique on dry skull.

The authors compared the limit of perceptibility of transcranial radiographs and of the split-cast technique in detecting differences in condylar position. The study was carried out on two dried human skulls. The results indicated the split-cast method was superior to the radiographic method as it allowed differences in condylar position of 0.2 mm, both in sagittal and frontal plane, to be detected. The limit of perceptibility of transcranial radiographs for position differences in the sagittal plane was 0.6 mm for naked-eye examination and 0.2 mm when using the subtraction method. Differences in condylar position even as large as 0.6 mm in the frontal plane could not clearly be seen by naked-eye examination, and with the subtraction technique only if they were of at least 0.4 mm.

Humans↗

PubMed1983

The role of stress, occlusion, and condyle position in TMJ dysfunction-pain.

Lateral transcranial TMJ radiographs are duplicable within +/- 0.2 mm and are cross-sectional views of the lateral third of the condyle and fossa. The innate asymmetry of humans, when the right and left sides of the fossa and condyle are compared, was clinically insignificant. Tomograms are not indicated because they lack appropriate resolution and detail to evaluate qualitative bone changes; and because they are not an in-office procedure, the condylar position in the fossa is completely unreliable. A correlation was reported between condylar position in the fossa and TMJ dysfunction in over 320 patients. This observation suggests that a new definition of centric relation is indicated, a definition that differentiates whether it is functional or dysfunctional. The criterion is the correlation between the occlusal findings and the condylar position in the fossa as recorded by the lateral TMJ radiographs (when the teeth are in maximum occlusion). Stress response was found to be greater in males than in females (in all vertebrates, including humans); therefore stress cannot be a direct cause of craniomandibular pain since more women have the disorder. It was concluded that stress is an indirect contributing factor that usually works through the medium of clenching. The role of the neuromuscular mechanism in craniomandibular pain was discussed. Proprioception reflex activity forms the basis for muscle length, mandibular positional sense, as well as masticatory function. Occlusal disharmonies increase noxious input to the neuromuscular system, as well as stress-induced clenching, causing increased muscle activity and spasm-pain. Condylar displacement also contributes to TMJ dysfunction-pain, depending on its direction. Anterior condylar displacement can initially affect the muscles by inducing overfunctional response in the proprioceptive system. Posterior condylar displacement usually results in an intrajoint response consisting of a disk derangement, reciprocal clicking, possible anterior disk dislocation, possible pathologic swallowing pattern, and noxious stimulation to the proprioceptive system. These factors contribute to subsequent trismus, muscle spasm and pain, and long-term pathologic remodeling of the joint. A detailed history is necessary to evaluate the role of stress. The physical occlusal findings are correlated with the condylar displacement observed in the TMJ radiographs to diagnose and plan corrective treatment.

Dental Occlusion, Centric↗

PubMed2003

Proximal segment positioning in bilateral sagittal split osteotomy: intraoperative controlled positioning by a positioning splint.

PURPOSE: Most techniques of proximal segment positioning hinder intraoperative condyle displacement. However, merely maintaining condylar position cannot optimize the preoperative condyle-disc-fossa relationship. This study attempts to optimize condylar position in the osteotomy patient. PATIENTS AND METHODS: A study group of 23 bimaxillary operated patients had intraoperative joint positioning by positioning splint and plates (9 Angle Class II, 14 Class III). After assessing the habitual and appraising the optimized condyle position on preoperative sonograms and magnetic resonance images, positioning splints were constructed as acrylic occlusal wafers in a semi-individual articulator. Set in occlusion before adaptation of positioning plates, they were intended to move the condyles into the calculated position. Eighteen bimaxillary operated control patients had conventional plate positioning according to the habitual occlusion (9 Angle Class II, 9 Class III). Clinical follow-up, axiography, or sonography was maintained for 24 months. Preoperative lateral cephalograms were scrutinized for horizontal and vertical joint spaces and compared with the immediate postoperative radiography. RESULTS: Postoperative Class II study group patients had less dorsal and more vertical joint space and Class III patients more dorsal and vertical space compared with the controls. The study group exhibited significantly less postoperative dysfunction compared with the control group (2-way analysis of variance: P <.021, F = 9.2, alpha =.05 significance level), disc dislocation prevalence was lower (P <.07, F = 9.2), postoperative changes in condylar translation were smaller (P <.014, F = 4.9), and 8% skeletal relapses versus 22% in the controls were seen. CONCLUSIONS: A proximal segment-positioning splint effectively positioned the condyle in the desired direction, but with considerable relapse, significantly reduced postoperative dysfunction, disc dislocations, changes to the condylar translation, and incidence of skeletal relapse at 24-month follow-up.

Adolescent↗

PubMed1990

[Condylar retrusion in the algo-dysfunctional syndrome of the mastication apparatus].

Although T.M.J. dysfunction-pain syndrome is a multicausal affection, it is obvious that occlusal disturbance is one of the greater etiologic factors. In order to evaluate the role of condylar position in the glenoid fossa, a statistical study has been made on a 16 patients series. These patients presented an uni- or bilateral T.M.J. dysfunction-pain syndrome without arthrosis, ankylosis or traumatologic deformation. The vertical and horizontal relationships of the mandibular condyle to the temporal were quantitatively evaluated from lateral tomographs. Pain and clicking were noted (Y or N) for each of the 32 T.M.J. Condylar position doesn't seem to have any relation with clicking, which is present in cases of meniscus anterior displacement. On the contrary, condylar horizontal retrusion is statistically connected with pain (p less than 0.05) even if one can see condylar retroposition without pain. On the other hand, vertical changes in condylar position cannot be connected with pain. The importance of condylar retrusion in the pain-group can surely be related to inflammatory histologic injuries at the level of the posterior disc attachment. Then, in these cases, the etiologic treatment must be focused on anterior mandibular release by orthodontics, prosthetics or orthognathic surgery.

Adolescent↗

PubMed1991

Condyle position and mobility before and after intraoral vertical ramus osteotomies and neuromuscular rehabilitation.

Correction of dentofacial deformities in patients with existing temporomandibular dysfunction and pain by intraoral vertical ramus osteotomies may result in improved function and resolution of symptoms. A prospective study of condylar position and mobility was made in nine patients with anterior disk displacements with reduction and associated temporomandibular pain and dysfunction. Each patient was treated by bilateral intraoral vertical ramus osteotomies with 2 to 3 weeks of maxillomandibular fixation and no interosseous fixation of the proximal segment. Condylar position and mobility in the surgical group were compared with normative values derived from seven individuals without discernible pain or dysfunction. Immediately postoperatively, the condyle was consistently positioned anteriorly and inferiorly, but the condyles tended to return to their preoperative position. Condylar mobility after surgery exceeded presurgical mobility and was associated with improved mandibular function.

Centric Relation↗

PubMed2006

Orthognathic surgery in cleft patients.

Orthognathic surgery has become a standard procedure in cranio-maxillo-facial surgery during the past five decades. Based upon the elementary works by Obwegeser who introduced sagittal split ramus osteotomy in the early 1950s, this procedure has become the worldwide gold standard in mandibular orthognathic procedures by now. When devices for ensuring the centric condylar position throughout the entire surgery were introduced by Luhr in the early 1980s, modern understanding of complete functional rehabilitation in orthognathic surgery was further enhanced. Even though Le Fort I osteotomy was performed by Wassmund already in the 1920s, it took almost another 50 years until this procedure became accepted in surgery, mainly due to concerns for severe haemorrhage that may occur during surgery. Application of a compound condylar positioning device which was established to ensure and keep the exact condylar position throughout maxillary, mandibular, as well as during bimaxillary osteotomies, and to permit the targeted use of distraction devices. Among those, cleft patients also sometimes need orthognathic correction of typical micrognathia and pseudoprogenia in late adolescence or at early adult age as secondary cleft surgery procedures. In this overview, special emphasis will be placed on orthodontic treatment as well as on the technical prerequisites for the surgical procedure.

Cleft Palate↗

PubMed1991

Transcranial radiography and linear tomography: a comparative study.

There is continual controversy concerning the use of radiographs to determine the position of the mandibular condyle within the glenoid fossa for the diagnosis and treatment of temporomandibular disorders. This study compared joint space measurements from transcranial radiographs and linear tomographs with the anatomic joint space to determine whether condylar position could be accurately recorded radiographically. Anterior, superior, and posterior joint space dimensions were measured from projected radiographs with a sonic digitizer, whereas anatomic joint space dimensions were recorded from the thickness of polyether impressions of the joint space. Posterior/anterior joint space ratios were used to classify relative condylar position as anterior, concentric, or posterior. The Pearson correlations (alpha = 0.05) were calculated to determine the consistency between radiographic and anatomic joint space ratios. The corrected and standard transcranial projections did not accurately reproduce the anatomic joint spaces or the relative condylar positions. Only the corrected tomographic projection accurately reflected the condyle-fossa relationships.

Arthrography↗

PubMedDate not supplied

Occlusal appliance therapy in a short-term perspective in patients with temporomandibular disorders correlated to condyle position.

PURPOSE: The purposes of this study were to compare changes in the condyle-fossa relationship in patients with temporomandibular disorders of arthrogenous origin treated with either a stabilization or a control appliance in a double-blind controlled study, and to compare the changes in the condyle-fossa relationship with the short-term treatment effect in the two treatment groups. The radiographic appearance of the temporomandibular joint was also studied. MATERIALS AND METHODS: Fifty-eight patients with temporomandibular disorders of arthrogenous origin were assigned to two equally sized groups: a treatment group given a stabilization appliance; and a control group, given a control appliance. The study covered 10 weeks. The treatment outcome regarding changes in severity of temporomandibular joint pain on a verbal scale was compared to changes in the condyle-fossa relationship in horizontally corrected oblique lateral transcranial radiographs taken with and without the appliance. Condyle-fossa relationship and structural bone changes were observed before treatment in corrected lateral tomograms. RESULTS: The group treated with a stabilization appliance showed a changed condylar position significantly more often (P = 0.004) than the control group. Of the patients reporting a successful treatment outcome, significantly more (P = 0.006) showed a changed condyle position in the group treated with a stabilization appliance than in the group treated with a control appliance. CONCLUSION: In patients with temporomandibular disorders of arthrogenous origin, the short-term occlusal appliance therapy resulting in a changed condylar position gave relief of symptoms more often than if the condylar position was unchanged.

Adolescent↗