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PubMed1983

In vitro transformation of chondroprogenitor cells into osteoblasts and the formation of new membrane bone.

Mandibular condyles of fetal mice 19 to 20 days in utero were kept in an organ culture system for up to 10 days. After 2 days in culture the cartilage of the mandibular condyle appeared to have maintained all its inherent structural characteristics, including its various cell layers: chondroprogenitor, chondroblastic, and hypertrophic. After 5 days in culture no chondroblasts could be seen and, instead, the entire cartilage was occupied by hypertrophic chondrocytes. At the same time, the mesenchymal cells at the chondroprogenitor zone differentiated with osteoblasts which produced osteoid. Light microscopic examinations showed that the newly formed osteoid did not stain with acidic toluidine blue or with alcian blue, but stained intensively with the van Gieson stain and with Periodic acid-Schiff (PAS). The osteoid reacted with antibodies against type I collagen but not with antibodies against type II collagen. Electron microscopic examinations showed that the mineralization appeared to be associated with collagen fibers in bone rather than with matrix vesicles in the cartilage. The process of bone formation progressed with time and by the 10th day new bone replaced almost the entire cartilage, thus forming an expanded layer of membrane bone. This in vitro system represents an experimental model whereby undifferentiated precursor cells transform into osteoblasts with the subsequent formation of a typical membrane bone.

Animals↗
PubMed1999

Glenomandibular muscle band in the human TMJ: a muscular antagonist to Bennett movement?

The medial aspects of ten adult TMJs were dissected using an inferior, rather than the more traditional lateral approach. Additionally, five 25 mm3 cubes of cadaver tissue with the mandibular condyle at their center were serially cryosected and photographed. Axial MRI scans were also taken of the TMJs of two living subjects. A band of fibromuscular tissue was found to run horizontally from the medial pole of the mandibular condyle to insert in an area of the sphenoid in front of the squamotympanic fissure. It is postulated that this glenomandibular band acts as a muscular antagonist to lateral Bennett movement.

Adult↗
PubMed1995

Preliminary in situ identification of estrogen target cells in bone.

Although estrogens profoundly influence skeletal growth and maturation, their mechanism of action is still unclear. To identify their target cells in bone, estrogen receptors were located by immunofluorescence using the H222 monoclonal antibody in cryosections (both undecalcified and briefly decalcified) of hyperplastic mandibular condyle (persistent asymmetric mandibular growth) from a 14-year-old girl and radius and ulna from an 18-month-old female pig (epiphyseal fusion) and from a 3-month-old guinea pig (epiphyses open). Bone was removed from the animals at the peak of estrus. The most striking feature in all three species was the high proportion (approximately 50%) of receptor positive osteocytes. Although all sections contained active bone-forming surfaces, we were unable to identify clearly osteoblasts or lining cells that were estrogen receptor positive. In pig bone only, distinctive groups of receptor positive chondrocytes, with a pericellular localization of collagen type 1, were detected above the growth plate but below secondary centers of ossification. This observation suggests that osteocytes are major skeletal estrogen target cells and may be involved in coordinating the response of surface bone cells to the hormone, and further that chondrocytes may be involved in estrogen-induced epiphyseal growth plate fusion.

Adolescent↗
PubMed1998

[Activation of insulin-like growth factor 1 gene expression in growing rat condyle by functional mandibular protrusion].

OBJECTIVE: We studied the changes of the IGF-1 mRNA expression in condylar cartilage to elucidate the biomolecular mechanism of mandibular advancement. METHODS: Sixty 5-week-old male rats were randomly divided into experimental and control groups. The mimic functional appliances were used in experimental group. The rats were sacrificed after 1, 3, 7, 14, 21 and 28 days to study the expression of IGF-1 mRNA by in situ hybridization. RESULTS: The results showed IGF-1 mRNA expression in the condylar cartilage. The transitional and maturational layers had the most abundant IGF-1 mRNA, and the IGF-1 mRNA abundance of germinal layer is higher than that of synovial and fibrous layers. Functional mandibular protrusion activated the IGF-1 mRNA expression and it began to increase after 3 days of the experiment, and the changes were most significant in 7-14 days. CONCLUSION: This suggested that the condylar cartilage growth and remolding after functional protrusion might be caused by IGF-1 gene expression activation.

Animals↗
PubMed1987

[Craniofacial growth under the influence of blood supply. 10. Arthrosis of the temporomandibular joint].

Unilateral and bilateral deformation of the temporomandibular joint was observed in young rats after unilateral ligature of the common carotid artery. They involved both the mandibular condyle and the mandibular fossa and were usually associated with a reduction in the dry weight of the masticatory muscles on the ligated side. This leads to the assumption that muscular atrophy is causally related to arthropathy of the temporomandibular joint. The methodological approach to induce changes in the temporomandibular joint may be used as a model of arthrosis of that joint.

Age Factors↗
PubMed2002

Orthodontic finishing after TMJ disk manipulation and recapture.

Orthodontic treatment has as its goal in most patients to achieve a cosmetic and functional result. There are functional goals for all orthodontic treatment and in some few cases the functional outweigh the cosmetic; an example would be a cleft-palate case. Orthodontic finishing to a specific condylar position is not routinely a goal of orthodontic care. The reason for this is that only patients who have pain, dysfunction and a negative change in quality of life from their temporomandibular apparatus need this tangential type of treatment. Research has shown that most patients suffering from a temporomandibular disorder (TMD) have displacement of the temporomandibular disk(s). Research has shown that when the mandibular condyle is repositioned to the Gelb 4/7 position that the temporomandibular joint disk is recaptured to a normal position between 85% and 96% of the time. The Gelb 4/7 position has been equated to the physiologic position of the mandibular condyle in the glenoid fossa. TMJ condyle repositioning to the physiologic position has been correlated to disk recapture proven by magnetic resonance imaging (MRI). A case is shown in which a displacement without reduction is manipulated into reduction and maintained with orthodontic correction. TMJ disk displacement without reduction is usually preceded by TMJ disk displacement with reduction. Pumping of the upper joint compartment can assist in reducing the TMJ disk displacement without reduction. Magnetic resonance imaging before and after the manipulation and after orthodontic treatment are shown. A detailed method of orthodontic finishing that maintains a specific condylar position and TMJ disk recapture is shown.

Adolescent↗
PubMed2002

Treatment of painful temporomandibular joint dysfunction with the sagittal split ramus osteotomy.

PURPOSE: We describe a new indication for the sagittal split ramus osteotomy with rigid fixation to treat patients with painful dysfunction of the temporomandibular joint. PATIENTS AND METHODS: Ten patients for whom nonsurgical management failed were found to have a mandibular condyle positioned postero-superior within the glenoid fossa with reduced joint space on corrected-axis tomograms. The sagittal split ramus osteotomy was used to reposition the proximal segment and to increase joint space. Preoperative and long-term postoperative (average, 44.7 months) symptoms and tomographic findings were retrospectively compared. RESULTS: Significant pain relief occurred postoperatively in all patients. One patient had a relapse after initial improvement. No patient developed a malocclusion. The long-term radiographic condyle-fossa relationship tended to return to its preoperative position with no relapse of clinical symptoms, except in the 1 patient. CONCLUSION: The sagittal split ramus osteotomy with rigid fixation is another procedure that can be used to treat painful temporomandibular joint dysfunction by changing the position of the mandibular condyle in the glenoid fossa.

Adult↗
PubMed1993

Benign osteoblastoma associated with an aneurysmal bone cyst of the mandibular ramus and condyle.

This article reviews the clinical behavior, the histologic conditions, and the treatment of a benign osteoblastoma associated with an aneurysmal bone cyst of the mandibular condyle and ramus. A 14-year-old boy, otherwise healthy, was referred for pain and enlargement in his right temporomandibular joint-cheek region. The swelling was firm and tender, a slight facial asymmetry was present, and the mouth-opening capacity was reduced. During a 6-weeks period from the primary examination to surgery the lesion expanded extensively, anesthesia appeared in the right inferior alveolar nerve and a lateral open bite developed on the affected side. Computed tomography displayed a total destruction of the right mandibular condyle and ramus to the level of the mandibular foramen. The lesion was radiolucent without distinct borders to adjacent bone. Surgery revealed a bluish, well-vascularized predominantly cystic tumor. The lesion included the temporomandibular joint disk but without overgrowth to the temporal component. After resection of the lesion, the condyle and the mandibular ramus was reconstructed with the use of an autogenous costochondral graft. The postoperative healing was uncomplicated. At follow-up 2 years after surgery the boy was free of recurrence with normal motor and sensory nerve function.

Adolescent↗
PubMed1992

An analytic method for evaluating condylar position in the TMJ and its application to orthodontic patients with painful clicking.

The purpose of this study was to develop a new method for evaluating the three-dimensional position of the mandibular condyle relative to the glenoid fossa and further to investigate its clinical application to orthodontic patients with temporomandibular disorders (TMD). A three-dimensional configuration of the temporomandibular joint was constructed by 108 triangles for the condyle and 180 triangles for the glenoid fossa. The shortest distance between the condyle and glenoid fossa (CGFD) was calculated in the model along a line perpendicular to the center of gravity of a triangle on the condyle. The CGFD was determined in the anterior, posterior, middle, lateral, and medial areas on the condyle. Preliminary investigation revealed that the present technique is accurate, regardless of condylar rotation and/or inclination to the tomographic table. The technique was applied to the diagnosis of orthodontic patients with painful clicking and TMD. It is shown that the present approach provides a method for evaluating the positional relationship between the mandibular condyle and glenoid fossa in patients with TMD.

Adolescent↗
PubMed2003

[Effects of static tension-stress and TGF-beta 1 on proliferation of mandibular condylar chondrocytes].

OBJECTIVE: The purpose of this study was to investigate effects of static tension-stress and TGF-beta 1 on proliferation of mandibular condylar chondrocytes in vitro. METHODS: The fourth-passage chondrocytes were harvested from the mandibular condyles of 2-week-old SD rats for this study, and a cellular static tension-stress device was used to apply stress on cells. The effects of continuous static tension-stress and/or transforming growth factor-beta 1 (TGF-beta 1) on the proliferation of mandibular condylar chondrocytes were examined using flow cytometry. The experiment was divided into two parts. The first part consisted of 100 specimens which were divided into 20 groups with different TGF-beta 1 dosage (0 ng/ml, 0.1 ng/ml, 1 ng/ml and 10 ng/ml) for 0, 6, 12, 18 and 24 hours respectively. The second part consisted of 30 specimens which were divided into six groups under continuous static tension-stress (5 kPa) and different TGF-beta 1 dosage (0.1 ng/ml, 1 ng/ml, 10 ng/ml) for 0, 6 and 12 hours. Multivariable analyses were conducted to test for associations between proliferation of mandibular condylar chondrocytes and TGF-beta 1 and/or different stresses. RESULTS: The results showed that TGF-beta 1 had a mitogenic effect on rat mandibular condyle at the concentrations of 0.1, 1 and 10 ng/ml, and the mitogenic effects of TGF-beta 1 on condylar chondrocytes were demonstrated in 12 to 18 hours after application of stresses, and the peak of mitogenic effects appeared at 18 hour (P < 0.05). The most active mitogenesis happened in the group with continuous static tension-stress (5 kPa) combined with TGF-beta 1. CONCLUSION: These results prove mechanical stimulates and TGF-beta 1 in vitro could influence and regulate the growth of condylar chondrocytes.

Animals↗
PubMed1987

The in vitro behavior of fetal condylar cartilage in serum-free hormone-supplemented medium.

Mandibular condyles of fetal mice 19-20 days in utero were kept in a serum-free organ culture system for up to 14 days and were investigated for their capacity to develop osteoid and to mineralize in vitro. After 3 days in culture, the cartilage of the mandibular condyle appeared to have maintained all its inherent structural characteristics, including its various cell layers: chondroprogenitor, chondroblastic, and hypertrophic. After 7-9 days in culture, no chondroblasts could be seen; instead, most of the cartilage consisted of hypertrophic chondrocytes. In addition, various areas throughout the explant revealed the appearance of osteoidlike material. The process of matrix mineralization progressed with time, and by the 14th day new bonelike material was found to occupy a larger portion of the explant. The newly formed matrix reacted positively with antibodies against type I and type III collagens, as well as against bone alkaline phosphatase. Electron microscopic examination showed that the mineralization appeared to be associated with collagen fibers as well as the matrix vesicles. In composition, the in vitro-formed mineral deposits resembled hydroxyapatite crystals. Biochemical assays indicated that the newly formed tissue reacted strongly for alkaline phosphatase and incorporated 45Ca. The findings of the present study imply that fetal condylar cartilage possesses the potential to develop in vitro osseouslike tissue even in a system that is serum-free. Due to the fact that the newly formed extracellular matrix mineralized and reacted positively to bone markers as well as to cartilage macromolecules, it would seem justifiable to define the new tissue as chondroid bone.

Alkaline Phosphatase↗
PubMed1997

Computerized cephalometric evaluation of orthognathic surgical precision and stability in relation to maxillary superior repositioning combined with mandibular advancement or setback.

PURPOSE: A computerized, cephalometric, orthognathic surgical program (TIOPS) was applied in orthognathic surgical simulation, treatment planning, and postoperatively to assess precision and stability of bimaxillary orthognathic surgery. PATIENTS AND METHODS: Forty consecutive patients with dentofacial deformities requiring bimaxillary orthognathic surgery with maxillary superior repositioning combined with mandibular advancement or setback were included. All patients were managed with rigid internal fixation (RIF) of the maxilla and mandible and without maxillomandibular fixation (MMF). Preoperative cephalograms were analyzed and treatment plans produced by computerized surgical simulation. Planned, 5-week postoperative and 1-year postoperative maxillary and mandibular cephalometric-positions were compared. RESULTS: In the mandibular advancement group, the anterior maxilla was placed too far superiorly, with an inaccuracy of 0.4 mm. The posterior maxilla and the anterior mandible were placed in the planned positions. The lower posterior part of the mandibular ramus was placed too far anteriorly, with an inaccuracy of 2.0 mm. However, the mandibular condyles were accurately placed. In the setback group, the anterior maxilla was placed too far superiorly and posteriorly, with a vertical and sagittal inaccuracy of 1.0 mm and 0.7 mm, respectively. The posterior part of the maxilla was placed in a posterior position with an inaccuracy of 1.9 mm. The anterior mandible was placed too far anteriorly with an inaccuracy of 0.9 mm. The lower posterior part of the mandibular ramus was placed in a posterior position with an inaccuracy of 0.9 mm. However, the mandibular condyles were accurately placed. The statistical analysis of the 1-year stability data showed that the maxilla had moved 0.3 mm posteriorly in the advancement group and the lower incisors had moved 0.8 mm superiorly. No other significant positional maxillary or mandibular changes were found. In the setback group, the maxilla had moved 0.5 mm posteriorly, the anterior mandible 0.5 mm anteriorly, and the lower incisors 0.7 mm superiorly. No significant positional changes were seen in the mandibular ramus. CONCLUSION: The TIOPS computerized, cephalometric, orthognathic program is useful in orthognathic surgical simulation, planning, and prediction, and in postoperative evaluation of surgical precision and stability. The simulated treatment plan can be transferred to model surgery and finally to the orthognathic surgical procedures. The results show that this technique yields acceptable postoperative precision and stability.

Adolescent↗
PubMed1998

Relationship between condylar position, dentofacial deformity and temporomandibular joint dysfunction: an MRI and CT prospective study.

The possible relationship between the morphometric characteristics (condylar and temporomandibular joint (TMJ) disc position) of the TMJ and the TMJ clinical findings (normal versus TMJ disorders) in different types of dentofacial deformities was studied. Forty-eight patients with dentofacial deformities (96 TMJs) were investigated preoperatively and 10 patients (20 TMJs) without deformities were studied as a control group, clinically and radiographically, using computer tomography (CT) and magnetic resonance imaging (MRI), to assess the position of the mandibular condyle and the TMJ disc in the sagittal, coronal and horizontal planes. Fifteen of the 28 joints (53.6%) of patients diagnosed as class II dentofacial deformity had internal derangements and anteriorly displaced discs. The incidence of internal derangement in the class I and class III groups was lower (10%). An increased horizontal angle of the mandibular condyle and a posteriorly seated condyle were found in patients diagnosed as class II dentofacial deformity when compared with the control group. The rest of the patients studied showed no significant differences. The same results were encountered when the patients with moderate to severe TMJ pathology were studied, both clinically (using the Helkimo index modified by Athanasiou) and by MRI.

Adolescent↗
PubMed1992

Direct coronal computed tomography of the temporomandibular joint in patients with rheumatoid arthritis.

Direct coronal computed tomography (CT) of the temporomandibular joint (TMJ) was performed in 26 patients with rheumatoid arthritis (RA) and 26 control subjects. Erosions and cysts of the mandibular condyle had a significantly higher frequency in the RA group than in the control group (p < 0.05) but there was no significant difference in the incidence of other abnormalities. Bone changes were bilateral in RA. A wide range of CT abnormalities was present in patients with RA and in the control group. There are no CT abnormalities specific for RA, but the incidence of erosions and cysts of the mandibular condyle was significantly higher in the RA group and should suggest the diagnosis.

Arthritis, Rheumatoid↗
PubMed2005

The prevalence of osteoarthrosis in cases of advanced internal derangement of the temporomandibular joint: a clinical, surgical and histological study.

INTRODUCTION: The articular disk has a central role in the pathology of internal derangement of the Temporomandibular Joint (TMJ). What is less clear is the role of osteoarthrosis in the development of internal derangement. The aim of this study is to determine the prevalence of osteoarthrosis in cases of advanced and recalcitrant TMJ internal derangement that were treated by diskectomy. MATERIALS AND METHODS: This study involved 22 joints in 18 patients who underwent surgery for the treatment of advanced and recalcitrant internal derangement of the TMJ. All patients included in the study failed to respond to at least 6 months of pre-operative conservative treatment and the clinical diagnoses of advanced TMJ internal derangement were confirmed on pre-operative MRI's. Tissue specimens were obtained from all 22 joints for histopathology. The specimens included articular disks that were excised from all 22 joints which were found to have severely displaced and deformed disks that were judged to be irreparable at the time of surgery. Also included were eight tissue samples from the mandibular condyles that were judged to be diseased on pre-operative tomograms and at the time of surgery. All samples were prepared in serial sections in the standard way and examined under light microscopy by two experienced Oral Pathologists. RESULTS: There were 22 specimens of articular disk examined together with 8 specimens from the mandibular condyle. All 22 joints (100%) showed histological evidence of disk pathology and eight of the 22 joints (34.4%) were found to have condylar pathology. The most common disk pathology was hyalinization indicative of disk degeneration (12/22). The most common condylar pathology found was articular surface degeneration indicative of osteoarthrosis (8/22). CONCLUSION: The clinical and radiological diagnoses of advanced TMJ internal derangement correlated with histological findings of degeneration and inflammation of the articular disk in all 22 specimens. The 8 specimens obtained from the condylar head showed histological features consistent with osteoarthrosis. This study showed that osteoarthrosis and internal derangement were found to co-exist in the same joint in about one-third of cases. The fact that osteoarthrosis was not found in all cases suggests that perhaps the widely held view that subclinical osteoarthrosis may lead to pathologic tissue responses in the form of internal derangement will need to be re-examined.

Adolescent↗