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PubMed2005

[Relationship of the movement of mandibular condyle and occlusal force balance].

PURPOSE: The present investigation evaluated the relation between the dynamic properties of the bilateral condyle in habitual maximum opening and closing movement and the occlusal force balance with clenching force. METHODS: Nine normal adults participated in this study. The translation of bilateral condyle and the rotation of intercondylar axis in habitual maximum opening and closing movement was measured using Cadiax, (ver. 3.0). The amount of translation and the rotation were converted into percentages and plotted on a graph using the translation-rotation relative chart. The maximun difference (d) between right condyle and left condyle of translation in rotation was calculated. The maximum clenching force was measured using Dental prescale 50H, type R and Occluzer FPD-703 (Fujifilm Co., Ltd.) and the center of gravity of the occlusal force was plotted on the drawings in two dimensions (anterior-posterior, right-left). RESULTS: 1. The reproducibility of the dynamic properties of bilateral condyle in habitual maximum opening and closing movement and (d) were shown on the translation-rotation relative chart. 2. It was observed that the center of gravity of the occlusal force of a number of subjects was almost localized on the median line with right-left dimension and was localized on the molar tooth area with anterior-posterior dimension. 3. The correlation coefficient was 0.33 between the coordinate value of the center of gravity of the occlusal force with right-left dimension and the path of opening's (d). The coefficient was 0.71 between the coordinate value of the center of gravity of the occlusal force with right-left dimension and the path of closing's (d). CONCLUSIONS: The present study showed the correlation between the dynamic properties of the bilateral condyle in habitual maximum opening and closing movement and the occlusal force balance with maximum clenching force.

Adult↗
PubMed1987

Histomorphometry of age and sex changes in mandibular condyles of young human adults.

Changes in cartilage, subchondral bone and their interface were studied using sagittal (6-8 micron thick) sections from the lateral, central, and medial parts of 21 condyles (11 males and 10 females; aged 18-36 years). The presence of undifferentiated mesenchymal (UM) cells in the proliferative zone of the cartilage was noted. Five condyles were judged to be immature because they had hypertrophic cartilage, cartilage resorption and bone formation at the cartilage-bone interface, no compact bone in their anterior and the superior regions, and the many cartilage rests in subchondral bone. Four of these immature specimens were from males. Immature specimens had quantitatively thicker cartilage (p less than 0.01), thinner subchondral bone (p less than 0.005), and less bone, more vascular spaces and more cartilage rests, both at the cartilage-bone interface and in the subchondral bone (p less than 0.001). Of the 16 mature condyles, the older had fewer UM cells in the proliferative layer, thicker compact bone (p less than 0.05), less vascular spaces at the cartilage-bone interface (p less than 0.05) and more bone and less vascular spaces in the compact bone (p less than 0.05 and p less than 0.01 respectively). No significant differences were found between mature condyles of males and females, but females had more UM cells, less hyperplastic cartilage and fewer irregularities at the cartilage-bone interface.

Adolescent↗
PubMed1986

The effect of increased oxygen tension on the growth of the mandibular condyle.

Forty-eight Long Evans/Turku rats were exposed to increased oxygen tension at the age of 11 or 13 days. Three control and three experimental rats were killed after 3, 7, 11 and 14 days of exposure and 1, 5, 10, and 15 days after the animals had been returned to normal laboratory conditions. Glycosaminoglycan synthesis decreased when the oxygen tension increased, as indicated by reduced metachromasia of the cartilage. After the animals had been returned to normal laboratory conditions the glycosaminoglycan synthesis of chondroblasts and chondrocytes seemed to recover. Disturbances were seen in the intermediate cell layer of the condyle and later in the condylar cartilage. The results seem to indicate that there are differences in the metabolic state of the cells in different regions of the condyle. Variances in the metachromasia of the condylar cartilage appear to be affected by different oxygen tensions, which seem to be lowest in the superior region. The mesenchymal cells in particular seem to be sensitive to a drop in oxygen tension.

Animals↗
PubMed1990

Effect of bilateral asymmetric tooth clenching on load distribution at the mandibular condyles.

The effects of balancing-side tooth contacts on temporomandibular joint loads are unclear. We used a 3-D computer model to calculate the magnitude and direction of temporomandibular reaction forces during simulated clenching on interocclusal acrylic resin shims and between natural teeth. Muscle tensions were proportioned according to the task modeled. Working-side tooth contacts included the canine alone, as well as group function, and occlusal loads were progressively shifted toward a posterior contralateral simple balancing contact. In the acrylic resin shim experiments, group function with simple balancing contact yielded the highest forces at the load point and at both temporomandibular joints. Movement of the occlusal load toward the balancing side produced greater, anteriorly oriented forces on the working condyle. For natural teeth, changes in the angle of resultant tooth force (simulating facet angulation) greatly influenced condylar forces. As the occlusal load moved toward the balancing side, greater and more laterally oriented forces were produced on the balancing condyle. Unilateral clenching on the canine produced the least condylar and bite forces. The simulation involving natural teeth offers a possible explanation for deviations in form and osteoarthrosis at the temporomandibular joints.

Acrylic Resins↗
PubMedDate not supplied

Position of mandibular condyle at maximal mouth opening in symptom free subjects.

The purpose of this study was to ascertain maximal mouth opening in normal symptom free subjects and to evaluate radiographically the anatomic position of the condyle during such an opening. Also to find out the prevalence of clinical signs of TMJ dysfunction in asymptomatic subjects. Sixty subjects aged 15-45 years were selected according to stringent criteria. The clinical evaluation comprised of measurements of mouth opening, deviation on opening and assessing any joint sounds. Then transcranial radiographs were taken and different linear measurements were done. The values and correlations were analyzed using students 't' test. Females presented higher degree of clinical signs (joint sounds) of TMD than males. Almost all the subjects had their condyles translated beyond the articular eminence showing more of an inferior vertical shift. It is required that similar studies be conducted on different ethic population and different age groups. Results could be interesting and shed light in the relativity dark area of TMD.

Adolescent↗
PubMed1990

Positioning and mobility of the mandibular condyle after surgical correction of the asymmetric, prognathic mandible.

Following the extraoral vertical subcondylar osteotomy in the correction of the highly asymmetric and prognathic mandible, only insignificant radiographic changes were observed in the temporomandibular joint 12 months postoperatively. Slight morphologic alterations of the condylar seating were demonstrated at occlusion, but there was no significant difference in condylar position between the two sides of the surgically corrected asymmetric mandible. The condylar axis did not deviate from the preoperative situation, and condylar axis did not deviate from the preoperative situation, and condylar mobility was fully resumed 12 months postoperatively. The extraoral vertical subcondylar osteotomy procedure is applicable in the treatment of combined mandibular asymmetry and prognathism and does not create morphologic changes that differ in the two temporomandibular joints.

Adolescent↗
PubMed2004

[A case with osteochondroma of the mandibular condyle].

A rare case with osteochondroma located near the condylar process of the mandible is described. Surgical treatment was carried out (removal of the formation through the periauricular approach). Orthopedic treatment was carried out during the postoperative period. The proportions of the facial skull, occlusion, and articulation were completely restored.

Adult↗
PubMed1988

Transplantation of cryogenically preserved mandibular condyles in the adult and juvenile goat.

Loss of a functional temporomandibular joint (TMJ), due to various causes including tumor resection, joint disease such as osteonecrosis, and injury or trauma, has long been a clinical challenge in both children and adults. It may be a significant problem facing physicians during another war. While reconstruction to date has been performed with various prosthetic devices or autogenous costochondral grafts, these procedures have a potential for complications and morbidity. This procedure could adversely delay the return of military members to a combat unit, or affect their ability to serve as functional members of society. Our studies were performed to determine the feasibility of TMJ reconstruction techniques, healing, and long-term function and growth using cryogenically preserved mandibular allografts in the goat. This species was chosen because the surgical anatomy and biomechanics of the goat TMJ are very similar to that of the human. The positive results of the studies and their relevance to future military medical readiness and civilian medicine will be described.

Age Factors↗
PubMed1992

Predicted and observed shapes of human mandibular condyles.

A mathematical model based on linear programming was used to study the directions of the joint forces used to maintain the human jaw in three-dimensional static equilibrium when producing bite forces of 100 N to a maximum of 1000 N down the long axis of a central incisor, first premolar, first molar and third molar. Seven different versions of the model were studied. The two simplest versions minimized the total muscle tension and the total joint load, respectively. Assuming that the joint force direction must be normal to some part of the articular surface of the condyle, neither version produced directions consistent with the observed shapes of human condyles. The other five versions minimized different combinations of muscle tensions and joint loads. Two of these versions produced joint force directions compatible with the shapes of condyles. Both minimized total muscle tension plus the (vertical) joint load on the back of the condyle. The results suggest that joint mechanoreceptors (probably non-directional) as well as muscle receptors contribute to the neuromuscular control of bite forces. Our results are consistent with some recent observations [Marshall and Tatton, Exp. Brain Res. 83, 137-150 (1990)] of the cat knee joint.

Biomechanical Phenomena↗
PubMed2004

Bone SPECT in management of mandibular condyle hyperplasia. Report of a case and review of literature.

In the present paper we report the case of a 14-year-old girl suffering from condylar hyperplasia and enlargement of ipsilateral jaw body, stressing the importance of bone SPECT in the clinical management of this temporomandibular joint (TMJ) disorder. Condylar hyperplasia is an uncommon idiopathic monolateral disorder of jaw growth consistent with exuberant or persistent activity of the condyle nucleus finally involving sociopsychological aspects due to facial dysmorphism. Besides facial asymmetry our patient showed prognathism, malocclusion, worsening otalgia and headache. Conventional X-rays examinations and multislice spiral CT gave us important morphostructural information also thanks to 3D volume-rendered and virtual reconstructions, while bone SPECT by detecting an intense well focused (99m)Tc-MDP uptake allowed to achieve uninvasively the final diagnosis of primary condyle hyperplasia. In spite of the full imaging characterization of TMJ disorders, consensus on best timing and therapeutic approaches on condylar hyperplasia is yet to be reached. In the present case patient was first treated orthodontically, planning a "high" condylectomy intervention after at least 6 months.

Adolescent↗
PubMed1989

Reconstruction of the mandibular condyle using ramus osteotomies: a preliminary report.

Reconstruction is required for a number of conditions in which condylar bone is lost resulting in dental and skeletal change. Ramus osteotomies are described as an alternative to the currently used methods. Four cases are described to illustrate the use of this technique. These osteotomies have several advantages over other methods and have the potential for better functional results.

Adult↗
PubMed1999

Alterations of matrix- and cell-associated proteoglycans inhibit osteogenesis and growth response to fibroblast growth factor-2 in cultured rat mandibular condyle and calvaria.

Matrix and cell surface proteoglycans (PGs) may play important roles in the control of cellular actions of heparan-binding growth factors such as fibroblast growth factor (FGF) during chondrogenesis and osteogenesis. In this study, we used 4-methylumbelliferyl-beta-d-xyloside, an inhibitor of PG synthesis, and sodium chlorate, a competitive inhibitor of glycoconjugate sulfation, to determine the functional consequences of alterations of PG metabolism on osteogenesis and on FGF actions in neonatal rat condyle and calvaria in vitro. Biochemical analysis showed that beta-d-xyloside (1 mM) or chlorate (15 mM) treatment for 1-8 days inhibited cellular PG synthesis by 60-80% in condyle and calvaria, as evaluated by [35S]sulfate incorporation. Histochemistry and immunohistochemistry showed that the inhibition of PG synthesis by beta-d-xyloside resulted in reduced incorporation of chondroitin sulfate into cartilage and bone matrix. This was associated with a 75% reduction in cell growth in condyle, determined by DNA synthesis, and in collagenous matrix synthesis in condyle and calvaria, evaluated by tritiated proline incorporation and type I collagen immunohistochemistry. Morphological and quantitative autoradiographic analyses also showed that inhibition of PG synthesis by beta-d-xyloside blocked bone matrix formation by perichondral progenitor cells in condyles and by osteoblasts in calvaria. In addition, alteration of PG metabolism blocked the mitogenic response to rhFGF-2 in calvaria. The data show that functional proteoglycans are essential for osteogenesis and for the growth response to FGF-2 during osteogenic differentiation in vitro.

Animals↗
PubMed1989

[Planning a replacement for the mandibular condyle based on anthropologic findings].

The sizes of the bilateral capitulum of 467 jaws coming a paleoanthropological collection were evaluated by computer and statistically processed. No essential size differences were found between the right and the left side. Deviations between groups of men and women proved to be significant from a statistical point of view. However, practically, they were found insignificant for composing average jaw capitulum series of five pieces. The data help to design jaw capitulum prostheses and the making of their wax models.

Anthropology↗
PubMed1985

Assessment of mandibular condyle position: a comparison of transcranial radiographs and linear tomograms.

Transcranial radiographs are frequently used to assess condyle-fossa relationships. However, their validity in representing condyle position has been questioned. Intermethod comparisons were performed between methods assessing condyle position by subjective evaluation and by linear and area measurement of the interarticular space. Linear measurement of the subjective closest anterior and posterior interarticular space and subjective evaluation were the mutually preferred methods in both transcranial radiographs and tomograms. Statistically significant correlations were shown (p less than 0.05) for condyle position between pairs of clinical transcranial radiographs and linear tomograms of the same temporomandibular joints. However there was a qualitative concordance in assessed posterior concentric and anterior positions in only 80% of the pairs, and a full concordance in the degree of condylar displacement was found in only 60% of the cases. Although still clinically helpful, the use of transcranial radiographs to monitor small changes in condylar position relative to the tomogram was questioned.

Cephalometry↗