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At least 343 records · Page 19Linked to original sources
PubMed2004

The influence of pre- and intraoperative positioning of the condyle in the centre of the articular fossa on the position of the disc in orthognathic surgery. A magnetic resonance study.

OBJECTIVE: We investigated the changes in the temporomandibular joint (TMJ) after bilateral sagittal split osteotomy of the mandible for orthognathic surgery and the influence of positioning of the condylar process in the centre of the articular fossa before and during the operation for preventing changes in the TMJ postoperatively. STUDY DESIGN: A total of 28 patients with mandibular retrognathism had bilateral sagittal split osteotomies for mandibular advancement. In one group of 14 patients (28 TMJ), the condyles were placed in the centre of the articular fossa before and during the operation, and in the other group they were not. Differences on magnetic resonance imaging (MRI) were calculated and the results were evaluated. RESULTS: The main differences were found at maximal mouth opening. 15/28 TMJs (54%) that had not been positioned changed the position of the disc from physiological to anterior disc derangement with and without reduction postoperatively. In the 28 that had been positioned, changes were found in only 3 TMJs (11%) postoperatively. CONCLUSIONS: Fixing the condylar process in the centre of the articular fossa intraoperatively before bilateral sagittal split osteotomy is a factor in preventing postoperative structural changes in the temporomandibular joint.

Humans↗
PubMed1992

Orthodontic finalization following therapy with an anterior repositioning splint.

After phase I splint therapy for the management of posterior condylar displacement, it is not unusual to find that a posterior open bite has been created. Finalization of a new occlusal position may be effected via occlusal equilibration, prosthodontics, orthodontics, orthognathic surgery, or a combination of these procedures. Stabilizing the occlusion with orthodontics in the new orthopedic jaw position requires a systemic approach. This article outlines a strategy for orthodontic finalization in phase II therapy. The splint-guided position is maintained while intra-arch and interarch malocclusions are corrected. The objective in treatment of posterior condylar displacement via splint therapy and orthodontics lies in the provision of a sound condylar position and the movement of the teeth and mandible into a stable and esthetic position.

Adolescent↗
PubMed2001

The temporomandibular joint and the disc-condyle relationship after functional orthopaedic treatment: a magnetic resonance imaging study.

Causative correction of Class II skeletal malocclusions may be achieved through bite jumping by various means. Numerous animal experiments have yielded evidence of remodelled temporomandibular structures after mandibular protrusion. However, the mode and extent of structural and/or topographic changes of the disc-condyle relationship after functional orthopaedic treatment is still unresolved. A problem exists in defining the physiological position of the condyles and disc-condyle relationship, which is tentatively determined by various methods particularly in magnetic resonance tomographic studies. Despite the high resolution provided, the results have to be interpreted with caution, as osseous resorption and apposition cannot be assessed by visual evidence. This investigation examined the impact on the temporomandibular joints (TMJ), i.e. the condylar shape and position, and the disc-condyle relationship, of the bionator plus extra-oral traction in combination with vertical elastics. The underlying reactions were studied by means of magnetic resonance images (MRI) obtained from n = 15 successfully treated patients (mean age 11.6 years).

Activator Appliances↗
PubMed1992

[Fractures of the condylar region].

Condylar fracture are responsible for: homolateral TMJ disorders following discal apparatus lesions such as: disc displacement, discal lesion, osteoarthrosis of articular surfaces (condylar and temporal), contralateral TMJ disorders, more frequent, with destabilisation of the masticatory apparatus and decrease of ramus height or compensatory hypermobility. Functional treatment can prevent articular and muscular ankylosis. It is often indicated: non-displaced low undercondylar fractures or after surgery. Surgical reduction is indicated in two cases: displaced-low undercondylar fracture. The discal apparatus is intact and function usually excellent, displaced-high undercondylar fractures with 90 degrees head luxation. The bone reduction and contention must be associated to discal apparatus control. If dislocated or displaced, the apparatus should be replaced and sutured. Four factors are implicated in articular function: the fracture position, bone displacement (condylar head in or out of the glenoid fossa), discal apparatus integrity (the lower layer of the retrodiscal tissue is involved in bone regeneration especially in infants), and the quality of occlusion.

Humans↗
PubMed1977

Anatomic and clinical evaluation of the relationship between the temporomandibular joint and occlusion.

An anatomic and clinical investigation of condylar remodeling; the position of the condyle in centric occlusion; and the relationships of these two factors to each other and to the features of the dentition are reported. Two groups of 100 adult crania were examined. The first group had complete or partially edentulous arches. In the second group, the dentition was complete and there were various degrees of abrasion. In addition, clinical and tomographic data were obtained from 70 patients with temporomandibular joint pain-dysfunction syndrome. Occlusion was also studied by intraoral registration of the gothic arch and by mounting the casts on an articulator in 40 patients. Comparison of the data made it clear that occlusal conditions determine the course of condylar remodeling and lead to marked changes in shape of the joints. Occlusal disorders are also responsible for condylar displacement (noted in 51.4 per cent of patients), which, in turn, may be the cause of typical reshaping of the joint. These findings cast doubt on the proposition that the gnathologic determinants (particularly centric relation) are never changed in the course of time.

Adolescent↗
PubMed1981

The importance of radiography in the diagnosis of TMJ dysfunctions. A comparative evaluation of transcranial radiographs and serial tomography.

Eight men and 22 women with TMJ pain-dysfunction syndrome were selected. After clinical examination, TR and serial tomography were performed in 5 to 7 different planes. In 27 patients, TR showed a condylar displacement. This was confirmed by serial tomography, which also showed that the apparent position may vary from the medial to the lateral aspects due to rotation in some patients. Changes in shape were a common feature and did not necessarily occur in the same manner on each side or in the different sections of the same condyle. In these patients, the TR shape was generally more similar to that of the middle and lateral tomographic planes. The relationship between remodeling pattern and condylar position was confirmed. Degenerative lesions were present in some patients but could only be clearly detected by serial tomography. This study confirms the important role of the TMJ in dysfunctions and the validity of radiography in diagnosis.

Adolescent↗
PubMed1992

Estimated and true hinge axis: a comparison of condylar displacements.

The purposes of the investigation were: i) to compare the condylar displacements from centric slides for 74 sets of casts mounted with an estimated versus a true hinge axis; ii) to determine the error in hinge axes location on the recording of condylar displacements from centric slides; and iii) to define the reproducibility of the Mandibular Position Indicator (MPI), a method of measuring condylar (in vitro) displacements from centric relation position. The findings revealed that routine use of the true hinge axis to obtain MPI readings for analysis of diagnostic casts is not warranted. The mean standard error of MPI double readings attributed to both hinge axes location was 0.4 mm for each component in the sagittal plane. Of the 0.4 mm of mean standard error, 0.2 mm was contributed by the lack of reproducibility of the MPI. The centric relation bite registration technique outlined in this study always captured a superior articulator position of the condylar mechanism. The condylar distractions and deflections from centric relation to maximum intercuspation were primarily in an inferior direction with a smaller posterior component.

Centric Relation↗
PubMed2002

In vivo comparison of femorotibial contact positions for press-fit posterior stabilized and posterior cruciate-retaining total knee arthroplasties.

The objective of this study was to determine the in vivo medial and lateral femorotibial condyle contact positions for 20 subjects having either a posterior cruciate-retaining (PCR) or posterior-stabilized (PS) total knee arthroplasty (TKA) while sitting and kneeling. The two-dimensional radiographic images were converted into three-dimensional images using an iterative computer model-fitting technique. Anteroposterior contact positions, axial rotation, and condylar lift-off were assessed for each subject. In a seated position, the femorotibial contact points were, on average, posterior for both TKA groups (PCR: medial = -2.4 mm, lateral = -3.4 mm; PS: medial = -5.1 mm, lateral = -8.9 mm; medial, P=.21; lateral, P=.08). In a kneeling position, the contact position shifted anteriorly for the PCR TKA group (medial = 0.9 mm, lateral = -0.8 mm), whereas the contact positions in the PS TKA group remained posterior (medial = -5.6 mm, lateral = -8.3 mm; medial, P=.002; lateral, P=.0004). It is hypothesized that while in a kneeling position, the posterior cruciate ligament has less resistance to the anterior thrust of the femur relative to the tibia than in a PS TKA, in which this force is absorbed in the cam-and-post mechanism.

Arthroplasty, Replacement, Knee↗
PubMed2001

The Mitek mini anchor for TMJ disc repositioning: surgical technique and results.

This study evaluated our treatment outcomes in 105 patients (188 discs) using the Mitek mini anchor for temporomandibular joint (TMJ) articular disc repositioning surgery, with 88 patients having simultaneous orthognathic surgery. Criteria for inclusion into the study were: (1) Presurgical TMJ disc displacement with salvageable disc; (2) No prior TMJ surgery; (3) TMJ disc repositioning with the Mitek mini anchor; (4) Absence of connective tissue/autoimmune disease; (5) Absence of postsurgical trauma; and (6) Minimum of 12 months postsurgery follow up. Presurgery (T1), immediately postsurgery (T2), and longest follow up (LFU) clinical and radiographic evaluations were performed. The mean age of the patients was 32.6 years (range 14-57 years), and mean follow-up time was 46.2 months (range 14-84 months). Radiographic evaluation at LFU demonstrated no significant condylar resorption or positional changes of the anchors. At LFU, there was a statistically significant reduction in: TMJ pain, facial pain, headaches, TMJ noises and disability, and improvement in jaw function and diet. Maximum incisal opening improved slightly and lateral excursive movements decreased slightly. The Mitek mini anchor provides a predictable method for stabilizing the TMJ articular disc to the condyle and a high success rate in decreasing TMJ dysfunction and pain in patients with no previous TMJ surgery.

Adolescent↗
PubMed1995

Submentovertex radiology: cephalometric considerations in temporomandibular dysfunction.

Controversy exists in the literature concerning the association between the radiographic and the clinical features of the temporomandibular dysfunction (TMD). Hence, this study reinvestigated possible correlations between radiographically detected asymmetries and the clinical signs and symptoms of TMD. Complete clinical and radiographic records were gathered from 52 patients sequentially referred for corrected angle tomographs of the temporomandibular joint (TMJ). Measurements from submentovertex (SMV), lateral and posterior-anterior (PA) cephalographs and corrected angle parasagittal tomographs and recorded clinical signs and symptoms of TMD were the data inputs. Significant findings were as follows: a) as the discrepancy in the posterior condyle to pogonion measurement increased, the pogonion and both maxillary and mandibular incisors shifted laterally towards the shorter side; b) as the ANB angle increased, so did the difference in condylar angle measurements between the two condyles; c) the side with the larger condylar angle was positioned forward on the SMV; and d) a perpendicular bisector (Marmary's Centerline) of the line drawn between the right and left foramen spinosum was found to be a reliable baseline reference for SMV analyses. No statistically significant relation was found linking specific signs and symptoms of TMD to maxillofacial asymmetries recorded on SMV, lateral or PA cephalographs. None of the radiographic signs studied were found to be good predictors of specific signs and symptoms in TMD.

Analysis of Variance↗
PubMed1992

The cranial base in subjects with dental and skeletal Class II.

The aim of this study was to test to what extent the cranial base variations may be involved in Class II facial organization. Using Bonferonni probabilities, cranial base size and shape, and facial divergence were compared in two groups: an experimental group of 45 subjects with dental and skeletal Class II and an homologous control group of 41 subjects with a natural Class I ideal occlusion. In all individuals of the experimental group the Class II molar relationship was at least equal to the width of one premolar and the ANB angle was greater than the value of the mean +2 standard deviations of the ANB in the control group. Spacing and crowding was less than 2 mm at each arch in both groups; all subjects were between 10 and 12 years old. The anterior part of the cranial base (SN length and SNBa angle) was identical in the two groups, but in Class II, cranial base flexure (BaSN angle) was more obtuse (P less than 0.05) and posterior cranial base angle (SBaN) was more acute (P less than 0.01). These variations co-existed in the same group with a more retruded position of the condylar neck in the face (P less than 0.01) favouring per se a post-normal relationship of the mandible to the maxilla. The increased extension of the saddle angle in Class II could not be considered here as related to an hyperdivergent facial pattern since facial divergence was unchanged in Class II. Saddle angle and divergence correlated in Class I (r = 0.40; P less than 0.01), but not in Class II.(ABSTRACT TRUNCATED AT 250 WORDS)

Cephalometry↗
PubMed1990

[Use of titanium osteosynthesis in maxillofacial traumatology and orthognathic surgery].

This paper reviews the clinical use of titanium miniplate osteosynthesis in maxillofacial traumatology and orthognathic surgery. These materials were originally developed for treatment of mandibular fractures, but the application has within recent years been extended to other fractures of the facial skeleton and orthognathic surgery. The osteosynthesis increase stability in many situations, and may reduce or eliminate the need for post-operative intermaxillary fixation, by which morbidity, hospitalization period and period of sick-leave can be reduced. In orthognathic surgery, the stability of the miniplate osteosynthesis increase the demand for precision during surgery as compared to conventional fixation with wire osteosynthesis and intermaxillary fixation. Further refinements of the technique are, however, necessary in the future, as the current techniques does not always allow a sufficient reproduction of the position of the condylar segment.

Bone Plates↗
PubMed2000

Comparative study of the temporomandibular joint space in maximum intercuspation and canine edge-to-edge positions in deep bite and non-deep bite subjects.

In order to study the relationship between morphological properties of the TMJ and the mathematically predicted force distribution in the TMJ, the geometric distribution of the joint space on top of the condylar surfaces was evaluated. Seven deep bite subjects and seven non-deep bite subjects were used, and the joint space in the maximum intercuspation and canine edge-to-edge positions was analysed in each group. Standardized images of the TMJ were taken with computed tomography (CT) using a mandible positioner. The comparative ratio of joint space (CRJS) between the maximum intercuspation and the canine edge-to-edge positions was calculated and summarized on the map of the mean morphological outline of the condyle. On the balancing-side condyle, the CRJS of small value was distributed mainly on the anterior edge of the condyle in the non-deep bite group, whereas, in the deep bite group, it was distributed on the centre of the condyle. On the working-side condyle, the small CRJS was distributed around the lateral pole of the condyle in the non-deep bite group, whereas, in the deep bite group, it was found around the posterior part of the condyle. The distribution pattern of CRJS on the upper surface of the condyle in the non-deep bite group was consistent with the results of previous studies on mathematical simulation of TMJ loading. From the results of this study, it was suggested that the distribution of mechanical loading on the TMJ in the eccentric mandibular position would be highly affected by the comparative ratio of joint space. As the comparative ratio of joint space would be highly affected by the condylar position, the analysis of the morphology of the TMJ in relation to mechanical joint loading, in a future investigation, should be carried out on specific mandibular positions in relation to the function of the TMJ to be studied.

Adult↗
PubMed1975

Anterior condylar displacement: its diagnosis and treatment.

A deflective slide in centric relation to centric occlusion does not necessarily mean anterior condylar displacement. Its diagnosis and treatment depend on the correlation of three factors: the direction and magnitude of the mandibular slide from centric relation to centric occlusion, the change in vertical dimension of occlusion during the slide, and the position of the condyles in the fossae when the teeth are in the maximum occlusion (centric occlusion). When the change in vertical dimension almost equals to amount of slide from the deflective contact in centric relation to maximum intercuspation, very little anterior condylar displacement would be expected. Conversely, with proportionately little change in vertical dimension, more anterior condylar translation is required for a given degree of anterior slide. Examples of each type of anterior slide were related to the TMJ radiographs of the condylar position. If the direction and magnitude of the deflective occlusal contact can be correlated with the TMJ radiographs, the centric relation is ""functional,'' and the clinically retruded mandibular position should be used. When this correlation does not exist, the centric relation is ""dysfunctional'' and the terminal hinge position (retruded mandibular position) should not be used for restorative or corrective procedures. Examples of anterior condylar displacement were given, including deviation, with a comparison of ""before'' and ""after'' TMJ radiographs.

Dental Occlusion, Centric↗