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Results for “Condylar position”

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PubMed1961

Response of condylar growth cartilage to induced stresses.

The endochondral growth apparatus of the mandibular condyles, in contrast to epiphyseal plates of long bones, reacts positively to mechanical stimulation. Roentgenographic and histologic analyses of the joint structures of two experimental rhesus monkeys, when compared with untreated controls, showed obvious morphologic and structural transformations of the condylar heads as the result of the instituted treatment. Corollary differences were found in the ontogenetic and histogenetic pattern, as well as in the hormonal control, of these condylar growth centers.

Bone and Bones↗

PubMed2006

Clinical, radiographic and MRI findings of the temporomandibular joint in patients with different rheumatic diseases.

The aim of this study was to investigate the condition of the temporomandibular joint (TMJ) in patients with different rheumatic diseases, and report correlations between the clinical, radiographic and magnetic resonance imaging (MRI) findings. The 67 patients were divided into four groups: 16 with rheumatoid arthritis (RA), 15 with mixed connective tissue disease (MCTD), 18 with ankylosing spondylitis (AS) and 18 with spondyloarthropathy (SPA). They were clinically examined, and panoramic tomography, lateral panoramic radiography and MRI of the TMJ were performed. MRI showed reduced articular cartilage in 25% (4/16) of RA, 0% (0/15) of MCTD, 17% (3/18) of AS and 17% (3/18) of SPA patients. Condylar changes included erosion, osteophytes and abnormal shape. Disc alterations included perforation, abnormal anterior position and decreased movement. These abnormalities were most frequent in RA patients, and least frequent in MCTD and SPA patients. Crepitation and reduced maximum opening of the mouth correlated with abnormalities of the disc and articular cartilage as shown by MRI. Severe condylar erosion in panoramic tomograms significantly correlated with MRI findings of condylar erosion (P<0.01), diminished thickness of condylar cartilage, abnormal condylar shape, and abnormal shape of the temporal surface of the TMJ (P< or =0.001). The presence of crepitation, limited mandibular movement and/or pain on movement of the jaw often indicated structural damage to the TMJ. Panoramic radiographs provide an alternative method to MRI but, to obtain a more detailed anatomic picture, MRI is recommended for patients with acute unexplained pain or as part of preoperative work up. A panoramic recording is not indicated when MRI is planned.

Adult↗

PubMed2006

Experimental evaluation of three osteosynthesis devices used for stabilizing condylar fractures of the mandible.

INTRODUCTION: The purpose of the study is to evaluate experimentally the quality of the primary stability achieved in treating low subcondylar fractures by means of three different osteosynthesis devices. MATERIAL AND METHODS: The devices, a standard four-hole plate, an axial lag screw and a three-dimensional rectangular plate were tested on fresh isolated human mandibles. Testing was done on a test bench by reproducing static biting exercises between the first molars on the side of the fracture. The quality of the osteosynthesis was assessed by measuring the macroscopic amount of fragment displacement and on the device's ability to diffuse the mechanical strain within the fractured area by photoelastic stress analysis. RESULTS: The straight plates provided the worst restoration. This was explained by the unfavourable position of the plate along compression lines. The axial lag screws allowed average stability. This was due to the difficulty of intra-medullary positioning of the screw, and by the compression of the fracture line. Rectangular plates allowed good stability associated with rather good restitution of the strains. These good results were assigned to the shape of the plate, one of its arms approximating the tensile strain lines. CONCLUSION: Positioning and shape of the osteosynthesis device are of prime importance for condylar fracture stabilization. None of the three tested devices was optimal but the three-dimensional plate was the best. There is a need to develop the geometry of new plates.

Bite Force↗

PubMed1977

A new articulator emphasizing centric occlusion and the anterior determinants.

A new articulator is described which has the advantages of the rigidity of a simple articulator in the upper member and the flexibility of an adjustable articulator in the lower member. A link between the members and the frame along with the posterior controls establishes a full range of functional chewing movements and defines the extreme lateral or border paths. The articulator has condylar element controls which permit releasing and remounting the mandibular cast in a manner that serves the same function as the split-cast technique, but this method is faster and shows the amount of discrepancy. The condylar element control is an improvement over existing devices for comparing interocclusal records in that it not only indicates differences in position but it also provides quick remounting of the casts in a working articulator. Other features of the articulator are: (1) a condylar lock mechanism which is activated by only a half turn, (2) adjustable spring tension, (3) precise long centric and wide centric controls, (4) an incisal pain which can be removed and replaced on the articulator without changing its setting, (5) a Bennett movement carefully selected to avoid the complication of a pantograph type of face-bow, and (6) a new sponge wall type of mounting plate which supports both casts for simultaneous mounting.

Dental Articulators↗

PubMed2006

[Seasonal rhythms of parathyroid hormone-related protein (PTHrP) expression in growing rats after functional mandibular protrusion].

OBJECTIVE: To study parathyroid hormone-related protein (PTHrP) expression during forward mandibular positioning and compare it with the expression during natural growth in different seasons. METHODS: Sixty-four SD rats were randomly divided into experimental and control groups. Each group were randomly divided into four groups according to seasons. Immunohistochemical (IHC) methods were used to test the protein expression of PTHrP. Macroscopic and microscopic approach were applied to analyze the results. RESULTS: PTHrP expressed in mandibular condylar cartilage (MCC), the expression was accelerated and enhanced when the mandible was positioned forward. Furthermore, there was a seasonal rhythm in the protein expression of PTHrP in both experimental and control groups. The protein expression in spring group rose more than other groups. CONCLUSION: The functional appliance therapy can enhance the protein expression of PTHrP. The enhancement has a seasonal rhythm, which indicates that for the functional treatment better results can be achieved in spring.

Animals↗

PubMed2006

3-D sonography for diagnosis of osteoarthrosis and disk degeneration of the temporomandibular joint, compared with MRI.

This study determined the value of three-dimensional (3-D) sonography for the assessment of osteoarthrosis and disk degeneration of the temporomandibular joint (TMJ). Sixty-eight patients (136 TMJ) with clinical dysfunction were examined by 272 sonographic 3-D scans. An 8- to 12.5-MHz motor-angulated transducer positioned inferior-parallel to the zygomatic arch scanned the region-of-interest. 3-D condylar morphology was compared with subsequent magnetic resonance imaging (MRI). Fifty-three datasets were complete, i.e., 106 TMJ, 212 examinations. 3-D sonographic examination took 5 min and attained 70% sensitivity/76% specificity/75% accuracy; positive predictive value was 44%%; negative predictive value was 90%. Disk degeneration was diagnosed synonymously with 64%/73%/71%/42%/ 87%. 3-D sonography proved to be reliable for exclusion of osteoarthrosis as disk degeneration compared with MRI, whereas the presence of osteoarthrosis and disk dislocation cannot be reliably diagnosed. Prospective use will include routine screening, using more sophisticated equipment with higher frequency in real-time 3-D viewing.

Adolescent↗

PubMed2004

[A study on relationship between the contour of articular eminence and traces of the condylar kinematic center and its application in TMD patients].

OBJECTIVE: To investigate the relationship between the contour of articular eminence and traces of the condylar kinematic center during jaw opening movement in healthy subjects, and compare trace characteristics of condylar kinematic center and MRI findings in TMD patients. METHODS: In 10 healthy subjects, jaw-opening motion was recorded. The kinematic center and terminal hinge axis point of the condyle were used as trace reference points. The contour of articular eminence was examined by MRI. Seven patients with TMD signs and/or symptoms (disk displacement) were selected for this study. The condylar trace was recorded during jaw protrusion and opening-closing. The internal derangement in temporomandibular joints was detected by MRI and defined as: (1). normal disk position, (2). disk displacement with reduction, (3). disk displacement without reduction. RESULTS: In healthy subjects, most of the opening traces of the kinematic center coincided with the contour of articular eminence (8/10 joints in left, 9/10 joints in right). For terminal hinge axis point, no trace coincided with the contour of articular eminence (0/20 joints in left and right). In TMD patients, according to MRI findings, the condylar traces of kinematic center in 3 normal disk position joints showed normal shape. However, in 6 disk displacements with reduction joints and 5 disk displacement without reduction joints, the condylar traces of kinematic center showed irregular patterns except 1 disk displacement with reduction joint. CONCLUSIONS: In comparison with the terminal hinge axis point, the opening traces of the kinematic center can be interpreted as the translatory movement of the condyle/disc along the articular eminence. The study suggests the use of kinematic center in condylar movement studies.

Adolescent↗

PubMed2006

Treatment effects of the edgewise Herbst appliance: a cephalometric and tomographic investigation.

INTRODUCTION: The crown Herbst appliance was introduced in the late 1980s because of shortcomings of the banded Herbst. In edgewise Herbst treatment, a fixed appliance is used with the crown Herbst to maximize the skeletal effects of treatment. Treatment response to the edgewise Herbst appliance has not been reported in the literature. Our objective was to investigate skeletal and dental changes in patients with Class II malocclusions treated with the edgewise Herbst appliance. METHODS: Fifty-two consecutive patients were treated with the edgewise Herbst appliance; 32 (18 girls, 14 boys) met the criterion of 16 months out of Herbst treatment and were included in the study. Mean treatment time with this appliance was 8.0 +/- 1.8 months. Patients in the mixed dentition received additional treatment with 2 x 4 appliances until proper overbite, overjet, and torque on the incisors and permanent first molars were achieved. Patients in the permanent dentition were treated with full appliances to finalize the occlusion. Cephalometric measurements were taken at pretreatment, posttreatment, and 16 months after removal of the Herbst appliance, and the results were compared with 32 untreated Class II subjects from the Bolton Brush Study, matched for sex, age, and cephalometric dentofacial morphology. Data were analyzed with ANOVA, Tukey-Kramer multiple comparison tests, and 2-tailed t tests. RESULTS: After 8 months of Herbst treatment, incisal relationship was overcorrected to an end-to-end incisal relationship and improved 8.4 mm, compared with the control group. The maxilla moved backward 1.4 mm at Point A, and the mandible moved forward 1.7 mm. The maxillary incisors moved lingually 1.7 mm, and the mandibular incisors were proclined 3.6 mm. The molars were corrected to a Class III relationship with a change of 7.2 mm compared with the control group. The mandible moved downward and forward. However, the condyle showed only 0.2 mm forward movement in the fossa. Sixteen months after appliance removal, the molars had relapsed into a Class I relationship, for a net change of 2.4 mm compared with the control group. Net overjet gain was 2.7 mm. Net restraint of maxillary growth was 1.3 mm, and net forward movement of the mandible was 1.0 mm. The maxillary incisors had no net movement, and the mandibular incisors had a net forward movement of 0.3 mm. Overall, skeletal change contributed 85% of the net overjet correction. CONCLUSIONS: Class II treatment with the edgewise Herbst appliance is accompanied by both skeletal and dental changes. The changes are stable, with significant skeletal differences remaining 16 months after appliance removal. The forward and downward movement of the mandible with minimal changes in the position of the condyles in the fossae suggests a combination of condylar growth and remodeling of the glenoid fossa with treatment.

Analysis of Variance↗

PubMed2006

Mandibular mechanics following osteotomy and appliance placement II: Bone strain on the body and condylar neck.

PURPOSE: The purpose of this investigation was to determine if the mechanical environment of the mandible is changed by osteotomy and fixation, as assessed by the measurement of bone strain on the condylar neck and mandibular corpus. MATERIALS AND METHODS: Immediately following unilateral mandibular osteotomy and distractor placement, strain gauges were attached directly to the corpus and condylar neck in a sample of domestic pigs. Bone strains were recorded during mastication and muscle stimulation. Comparisons of principal strain magnitudes and orientations were made between sides and between the osteotomy sample and a control database. RESULTS: The animals preferred to chew on the non-osteotomy side. Corpus strains were higher for osteotomy-side chewing but were comparable to the control database, regardless of chewing side. For the condyle, compared with the control database and the non-osteotomy side, the osteotomy side was underloaded in compression. Furthermore, the orientation of compressive strain was highly variable and more horizontally oriented than that of control and non-osteotomy condyles. Stimulation of the masseter and medial pterygoid loaded the mandible to normal levels. CONCLUSION: Masticatory behavior was altered, probably as a combined result of disruption of the occlusion, changes in muscle recruitment, and probable loss of sensory feedback. However, neither these changes nor damage to the muscles explain the decrease and reorientation of compressive strain on the condylar neck. Alternatively, the modified strain pattern could have arisen from positional instability of the proximal bone fragment.

Animals↗

PubMed1991

Wall architecture and disc attachment of the human temporomandibular joint.

In an attempt to evaluate the potential behaviour of the temporomandibular joint wall during mandibular movements, joint specimens of 18 individuals, ranging in age from 15-45 years, were examined macroscopically and in the light microscope. The inner part of the joint wall was consistently formed by the superior and inferior lamina of the disc attachment. A distinct fibrous capsule existed in the posterior and lateral joint region, while anteriorly and medially, it could hardly be identified. The posterior attachment to the temporal bone of both the disc and capsule was clearly anterior to the squamotympanic and petrosquamosal fissure. A collagenous sheet inserting in and around these fissure was considered the deep lamina of the parotid-masseteric fascia. With reference to collagen arrangement, content in elastic fibres, and type of synovial lining, the postero-superior disc attachment appeared to be highly extensible, although not elastic enough to effectively pull the disc back upon posterior movements of the condyle. On the other hand, the latero-inferior disc attachment gave the impression of a rigid band well suited to drag the disc along with the condyle and still allowing condylar rotation. In addition, however, the postero-inferior disc attachment in combination with condylar rotation might also contribute effectively to the control of disc position on the moving condyle.

Adolescent↗

PubMed1977

[Quantitative interpretation of graphs from Stuart pantography. II. Geometrical bases].

In an experimental investigation, Stuart pantographic records are geometrically analyzed. The influence of the parameters' inclination and curving of condylar guidance, intercondylar distance, Bennett angle, distance of the plate, and position of the recording pencil are studied. Further quanitative analysis was not performed, as Stuart pantography is only meant for transmission to the respective articulator and is nto suitable for metric recording.

Dental Articulators↗

PubMed1994

[A study of computed tomography of elderly temporomandibular joint disorders syndrome (TMJDS) patients treated with and without splint in three dimensions].

The computed tomography of elderly TMJDS patients treated with and without splint were studied in three dimensions. The results showed that the condyle was in a retruded position in the glenoid fossa in sagittal dimension and the horizontal condylar angle appeared asymmetry in axial dimension. Under the splint treatment, the retruded condyle can be adjusted to the center of the glenoid fossa and the horizontal condylar angle can be balanced, since the splint may correct the vertical dimension and eliminate the occlusal interferences. This study indicates that the horizontal condylar angle can be considered as a significant factor in diagnosis of TMJDS and evaluation of the outcome of treatment.

Aged↗

PubMed1998

TMJ static disk: correlation between clinical findings and pseudodynamic magnetic resonance images.

The aim of this study was to analyze the position and mobility of the temporomandibular joint (TMJ) articular disk by means of pseudodynamic magnetic resonance imaging (MRI) and to compare: clinical features, osseus and muscular degenerative changes, the different types of static and their signs and symptoms. The study was performed on 101 patients with clinical and MRI diagnosis of TMJ internal derangement with closed lock (permanent or episodic). On the MRI survey the following was evaluated: disk displacement, disk mobility, condylar translation, bone, and muscular fatty atrophy. Pain was more frequent in static disks (SD) than in mobile disks (MD) in all types of disk displacements (p < 0.01). Condylar translation was always lower in SD than in MD, independently from the position of the articular disk (p < 0.01). Localized sclerosis was more frequent in joints with SD. There were no statistically significant differences in the incidence of fatty atrophy considering disk mobility. The results of the study indicate that clinical diagnosis of closed lock with high frequency is related to the presence of a static disk. Clinical diagnosis of SD can be confirmed with a pseudodynamic MRI survey.

Adolescent↗

PubMed2002

Mandibular condyle traits in Neanderthals and other Homo: a comparative, correlative, and ontogenetic study.

The relationship between the mandibular condyle and the crest of the mandibular notch (CMN) has historically entered into discussions of Neanderthal characteristics and was recently suggested to be autapomorphic in Neanderthals. The Neanderthal CMN has been described as intersecting the condyle in the middle, while the modern human CMN runs to the condyle's lateral end. A large lateral condylar tubercle (LCT) has also been observed in Neanderthals and thought to be related to medial (or less lateral) CMN position. In addition, the presence of a less lateral CMN early in ontogeny, as seen in the Amud 7 infant, has been argued to demonstrate great evolutionary divergence in Neanderthals. Using a scoring system for each trait, this study first examines the expression of CMN position and LCT size in 102 adult modern humans and in samples of Neanderthals and other fossil Homo. Then, CMN position is scored in 208 subadult modern humans to elucidate the ontogeny of this trait. Results show that CMN position is not autapomorphic in Neanderthals, but Neanderthals have significantly more CMNs in the least-lateral score category than does the modern human sample. Large LCTs are found to be strongly predictive of less lateral CMN position, although less lateral CMN position may exist in the absence of a large LCT. The complex ontogenetic pattern of CMN expression observed indicates that features of subadult and adult condylar morphology cannot be constructively compared without first considering subadult morphology on its own functional and developmental terms.

Adolescent↗

PubMed1997

Gonial angles and condylar and ramus height of the mandible in complete denture wearers--a panoramic radiograph study.

It has been accepted that the shape of the mandibular base, and especially the gonial angle of the mandible, correlates with the function of the jaw closing muscles. The gonial angles of the mandible and condylar and ramus heights of 30 complete denture wearers (18 women, 12 men, mean age 61 years, range 42-74 years) coming for renewal of their dentures were measured using panoramic radiographs. The mean period of edentulousness was 26 years (range 10-53 years). No statistically significant difference was observed between the sexes in the the sizes of gonial angles and condylar and ramus heights. The right gonial angle was statistically significantly smaller than the left one and correlated negatively with the ramus height in both sides but positively with the increased EMG activity in the right masseter muscle. The size of the gonial angle and the condylar and ramus heights did not correlate with the age of the patients, edentulous period or alveolar ridge resorption.

Adult↗

PubMed1990

High condylar shave of the temporomandibular joint with preservation of the articular soft tissue cover: an experimental study on rabbits.

The high condylar shave has the disadvantage of removing the articular soft tissue cover together with the underlying condylar bone. In an attempt to overcome this disadvantage, we elevated the articular soft tissue cover, shaved the condylar head, and replaced the articular soft tissue cover in its original position in nine adult rabbit temporomandibular joints. On the contralateral joints, the same amount of bone was shaved together with the articular soft tissue cover. The rabbits were killed after 3 months, and the condyles were macroscopically and histologically evaluated. All condyles were covered with an articular soft tissue layer in the area operated on. This surface was smoother when the articular soft tissue cover was preserved. Histologically, the subarticular layer of cartilage cells was continuous in the joints with preservation of the articular soft tissue cover but was frequently interrupted in the joints where this cover was removed. The incision made in the posterior part of the articular surface for elevating the articular soft tissue cover frequently caused a deformity of the condyle and an interruption of the subarticular layer of cartilage. The results suggest that preservation of the articular soft tissue cover on the mandibular condyle might be one way to improve the postoperative morphology after high condylar shave. The technique in its present state has obvious drawbacks and should be further refined before it is considered for clinical application.

Animals↗

PubMed2006

An impact of masticatory muscle function on IL-1beta and SOX9 expression in condyle.

The importance of masticatory muscle function on the growth and differentiation of condyle was examined. The aim of this study was to investigate how reduced masticatory muscle function influences intrinsic regulatory factors which govern growth and differentiation of condylar cartilage. Masseter muscles of 3-week-old Wistar rats were resected bilaterally. Masseteric resected animals and corresponding control animals were sacrificed at 3, 6, 12 and 21 days post-resection. The condyles were then processed for histological and immunohistochemical analysis. The expression patterns of an inhibitory regulator (IL-1beta) and a master regulator (Sox9) of chondrogenesis in condylar cartilage of growing rats were investigated. Quantitative analysis shows that masseteric resection significantly increased the number of IL-1beta positive cells in proliferative layer. In contrast, the number of Sox9 positive cells was significantly decreased compared to the control animals. It can be concluded that the reduced articular function due to masseteric resection decreased condylar cartilage cell differentiation which led to the decrease in the thickness of condylar cartilage.

Animals↗

PubMed1998

[Differential expression of IGF-I and its mRNA in mandibular condylar cartilage of rat--direct evidence for servosystem theory of facial growth].

It was studied the expression of IGF-I and its mRNA in the condylar cartilage of 10 7-week-old SD male rats by using in situ hybridization and immunohisto-chemistry technique. The results showed both IGF-I and its gene expressed in growing rat condyle. IGF-I peptide was abundant in germinal zone, and positive reaction of its mRNA was strongest in transitional and maturational zones. These indicate that condylar cartilage has the capability of local production and secretion of IGF-I, mediating the command effect of STH, and differential expression of IGF-I and its mRNA might establish the local feedback loop, which supply a direct evidence for servosystem theory of facial growth.

Animals↗