I . S . S . N 0 0 7 0 -9 4 8 4 EGYPTIAN DENTAL JOURNAL Degenerative effect of two Different techniques on conDylar cartilage of rabbits (original) (raw)
Related papers
Archives of Oral Biology, 2012
To test the null hypothesis that there is no difference in mandibular growth between growing rats with posterior functional mandibular displacement and growing rats without functional mandibular displacement. Materials and Methods: Twenty female Wistar rats (5 weeks old) were randomized into two groups: (1) control and (2) mandible posterior displacement in the occluded condition induced by an occlusal guiding appliance. After 8 weeks all animals were sacrificed, cone beam computed tomography scan images of the heads were taken using the classic I-CAT, and acrylic rapidprototyped templates of the mandibles were constructed. Mandibular length, ramus height, and intercondylar distance were measured. Mandibular length and ramus height were submitted to the two-way analysis of variance, while intercondylar distance was analyzed by nonpaired Student's t-test. Results: Mandibular length was bigger (P , .0001) in the control than in the experimental group, but no significant difference was found between the left and right sides (P 5 .9380). No significant differences were observed for ramus height and intercondylar distance. Conclusions: The results of this study demonstrated that functional posterior displacement of the mandible in growing rats resulted in shorter mandibular length. (Angle Orthod.
Archives of Oral Biology, 1996
The mammalian temporomandibular joint is a highly specialized diarthrodial joint under multidirectional compressive and tensile forces. In such a complicated biomechanical environment, the phenotypic expression of extracellular matrix may vary in different regions of the mandibular condylar cartilage. To test this hypothesis, immunohistochemical techniques were used to examine the localization of type I and type II collagens in various anterioposterior regions of the condylar cartilage of 4week-old rats. In the posterosuperior region, which is mainly subjected to compressive forces, a strong reaction for type II collagen was observed in the cartilaginous layer (maturative and hypertrophic cell layers), and a rather weak reaction was observed for type I collagen in the precartilaginous and cartilaginous layers, compared with the reactions in other peripheral regions. Proceeding anteriorly, staining for type I collagen increased, while that for type II collagen decreased. In posteroinferior cartilage, which is subjected mainly to tensile forces because of its direct attachment to the retrodiscal pad, staining for type I collagen was strong, and that for type II collagen was faint in the cartilaginous layer. These results demonstrate that marked regional differences exist in the phenotypic expression of two major collagen components in mandibular condylar cartilage, which may reflect the local functional environment and cellular response.
Journal of Orthodontics & Endodontics, 2018
Condylar growth modification is induced by mandibular advancement though the changes in Temporomandibular Joint (TMJ) after mandibular advancement could be permanently stable are not yet proved. Therefore, our purpose is to investigate the effects of mandibular advancement on the rat TMJ by changing in Matrix Metalloproteinases (MMPs) and Collagens (COLs) expression immunohistochemically (IHC) after retention treatment. In this study, 54 male Sprague-Dawley rats were divided to control group (n=24) and experimental group (n=30) for three months subgroups period. Only experimental subgroups were subjected to a full-time orthodontic inclined methyl methacrylate bite plate cemented to the incisors to advance the mandible for one month and continued as a half-day-wearer (retention period) till the end of the 2 nd month and stayed without appliance during whole 3 rd month (post retention period). Then, the assessment of gross-morphological changes of skull and the examination of the articular cartilage for each subgroup histologically in addition to IHC examination for MMP-1, MMP 8 and MMP 13 and COL-I, II and III were done. The grossmorphological changes were clear in experimental group as downward forward mandibular advancement in addition to a high significant decreased in the base mandibular length. There was also an abundant cellular proliferation at the condylar cartilage with a significant condylar ossification and higher osteoblastic activity in the experimental group obviously at retention period. Moreover, a significant increase in MMP-13 expression in both differentiation and hypertrophic layers of an experimental group during active and retention periods with reduction in the expression of COL-II in the experimental group was observed with no significant changes in other markers. These upregulation of MMP-13 in associated with significant reduction in expression of COL-II plays a significant role in cartilage collagen degradation and treatment stability, which is confirmed through the post-retention period due to endochondral ossification pattern improvement.
Phenotypic Changes of Rabbit Mandibular Condylar Cartilage Cells in Culture
Journal of Dental Research, 1990
The present study describes the behavior of mandibular condylar cartilage (MCC) cells as a function of time in primary culture, since it is not yet clear whether these cells maintain their phenotype in culture. MCC cells from New Zealand white rabbits were seeded at high density and cultured in DMEM containing 50 pig/mL ascorbic acid and 10% fetal bovine serum. These cells appeared as a heterogeneous population and changed their shape, size, and refractivity as cultures aged. Cartilagelike cells, which always dominated the culture, were infiltrated with a minority of fibroblast-like cells. Cell number increased progressively, and cultures reached confluence at nine days. Antibody activity for cartilage-specific glycosaminoglycan was determined by ELISA assay. This reaction reached a maximum at six days and decreased thereafter. Cultures stained with Alcian blue (pH 1.0) supported these results. Cytoplasmic mRNA analysis indicated that the transcription of type II collagen gene was present at all time points. Type I collagen and alkaline phosphatase mRNA levels showed progressive increases from 12 h to nine days, with significantly higher values in cells cultured for six, nine, and 12 days than in cells collected from earlier time points. These results suggest that in our present culture system, MCC cells undergo phenotypic changes that resemble their maturation processes in vivo.
Photobiomodulation, Photomedicine, and Laser Surgery, 2020
Objective: We evaluated the effects of photobiomodulation (PBM), mandibular advancement (MA), and the combination of both treatments (PBM+MA) on condylar growth, by the analysis of cartilage and bone formation, fibrillar collagen deposition, proteoglycan content, cell proliferation, and clastic cell index (CCI). Methods: Forty male Wistar rats were randomly assigned to CONTROL, PBM, positive control-MA, and PBM+MA groups. The appliance was worn 10 h/day. Laser was irradiated bilaterally on mandibular condyles in 8 alternate days (1 irradiation point per condyle) using the following parameters: 780 nm, 10 J/cm 2 , 40 mW, 1 W/cm 2 , 10 sec/point, 0.4 J/point, and cumulative dose per point: 3.2 J. PBM+MA received both treatments simultaneously. After 15 days, the animals were euthanized and the condyles dissected and embedded in paraffin. Histological sections from the intermediate portion of the condyle were used for morphometric analysis. The relative frequency (%) of fibrillar collagens was determined in sections stained with picrosirius red-hematoxylin under polarized light or Gömöri's method for reticular fibers. Proteoglycan content was evaluated by computerized photocolorimetric analysis. CCI was determined by tartrate-resistant acid phosphatase (TRAP), and proliferating cell nuclear antigen (PCNA) was detected by immunohistochemistry. Results: PBM and MA influenced condylar cartilage thickeness and matrix deposition, but none of the treatments affected significantly the area of the condyle. CCI were not influenced by the treatments, but clastic cells distribution was influenced by MA and PBM+MA treatments. There was no significant difference in proliferating cells among the groups. Conclusions: This study demonstrated that PBM and MA stimulates matrix deposition and cartilage thickening in the mandibular condyle, but was not able to demonstrate a synergistic effect between the treatments. Additional studies should be conducted to evaluate the possible synergistic effect between PBM and MA.
Bone, 2011
Osteoarthritis (OA) is a degenerative joint disease generally characterized by progressive cartilage degradation and subchondral bone changes. Subchondral bone changes have been proposed to initiate or accompany with cartilage degradation in OA. The purpose of this study was to characterize cartilage damage, subchondral bone remodeling, and the possible mechanism involved in these morphological changes in our reported rat model with OA-like lesions in the mandibular condyle. In experimental groups, the dental occlusion was orthodontically disturbed. By histological analysis, transmission electron microscopy (TEM), micro-CT scanning and serum tests, changes in condylar cartilage and subchondral bone were analyzed at 8 and 12 weeks after treatment. The mRNA and protein levels of bone pro-resorptive and pro-formative factors by chondrocytes were investigated. Increased degraded cartilage areas and obvious cartilage calcification were observed in 8-and 12-week treated (EXP) groups compared to the age-matched controls. Subchondral bone loss, characterized as decreased bone mineral density (BMD), bone volume fraction (BV/TV) and trabecular thickness (Tb.Th), but increased trabecular separation (Tb.Sp), was observed in the 12-week but not the 8-week EXP group, respectively, versus their age-matched controls. The subchondral bone loss in the 12-week EXP group was accompanied with decreased new bone formation rate, but increased serum carboxy terminal telopeptides (CTXs), and increased osteoclast numbers and proportion of surface area in the subchondral bone regions. Increased mRNA and protein levels of M-CSF, VEGF, RUNX and RANKL/OPG ratio, but decreased OPG, were found in condylar cartilage in the 12-week EXP group versus its age-matched controls, and those of RANKL/OPG ratios were significantly higher in the 12week EXP group than the 8-week EXP. In addition, increased mRNA levels of VEGF, RUNX and RANKL/OPG ratio, but decreased OPG, were also found in condylar cartilage in the 8-week EXP group versus its agematched controls (All P b 0.05). This study demonstrated that obvious subchondral bone loss followed cartilage degradation in the mandibular condyles in the present rat models and suggested that the imbalance of chondrocyte-secreted regulatory factors within the degraded cartilage may play a role in the osteoclastogenesis, and thus leading to the subchondral bone loss in OA.
Dental press journal of orthodontics
The mandibular condylar surface is made up of four layers, i.e., an external layer composed of dense connective tissue, followed by a layer of undifferentiated cells, hyaline cartilage and bone. Few studies have demonstrated the behavior of the condylar cartilage when the mandible is positioned posteriorly, as in treatments for correcting functional Class III malocclusion. The aim of this study was to assess the morphologic and histological aspects of rat condyles in response to posterior positioning of the mandible. Thirty five-week-old male Wistar rats were selected and randomly divided into two groups: A control group (C) and an experimental group (E) which received devices for inducing mandibular retrusion. The animals were euthanized at time intervals of 7, 21 and 30 days after the experiment had began. For histological analysis, total condylar thickness was measured, including the proliferative, hyaline and hypertrophic layers, as well as each layer separately, totaling 30 mea...
Microscopy Research and Technique, 2005
The hypertrophic chondrocytes lack the ability to proliferate, thus permitting matrix mineralization as well as vascular invasion from the bone in both the mandibular condyle and the epiphyseal cartilage. This study attempted to verify whether the histological appearance of the hypertrophic chondrocytes is in a steady state during postnatal development of the mouse mandibular condyle. Type X collagen immunohistochemistry apparently distinguished the fibrous layer described previously as the ''articular zone,'' ''articular layer,'' and ''resting zone'' from the hypertrophic zone. Interestingly, the ratio of the type X collagen-positive hypertrophic zone in the entire condyle seemed higher in the early stages but decreased in the later stages. Some apparently compacted cells in the hypertrophic zone showed proliferating cell nuclear antigen (PCNA) immunoreaction, indicating the potential for cell proliferation at the early stages. As the mice matured, in contrast, they further enlarged and assumed typical features of hypertrophic chondrocytes. Apoptotic cells were also discernible in the hypertrophic zone at the early but not later stages. Consistent with morphological configurations of hypertrophic chondrocytes, immunoreactions for alkaline phosphatase, osteopontin, and type I collagen were prominent at the later stage, but not the early stage. Cartilaginous matrices demonstrated scattered patches of mineralization at the early stage, but increased in their volume and connectivity at the later stage. Thus, the spatial and temporal occurrence of these immunoreactions as well as apoptosis likely reflect the prematurity of hypertrophying cells at the early stage, and imply a physiological relevance during the early development of the mandibular condyles.
Growth and growth pressure of mandibular condylar and some primary cartilages of the rat in vitro
American Journal of Orthodontics and Dentofacial Orthopedics, 1986
To compare the in vitro development of the secondary cartilage of the mandibular condyle with that of primary cartilages, several cartilaginous explants derived from 4-day-old rats were cultured in a serum-free culture system. The following cartilages were used: the mandibular condylar cartilage, the distal epiphyseal cartilage (including the growth plate) of the third metatarsal, a fragment of costal cartilage (including the osteochondral junction) of the fourth rib, the spheno-occipital synchondrosis and the chondroepiphysis of the femoral head. In addition, with a specially designed, in vitro pressure registration system, the maximal growth pressures for each of the explants, except the femoral head, were determined. The results show an independent growth potential for the primary cartilages of the epiphyseal and costal growth plates with a maximal growth pressure of 9.5 and 7.8 g/mm 2, respectively. The primary cartilage of the spheno-occipital synchondrosis, on the other hand, although it possesses an independent growth potential, could exert a maximum growth pressure of only 1.5 g/mm 2. The secondary cartilage of the mandibular condyle showed a limited intrinsic growth potential, as well as a low maximal growth pressure (2.6 g/mm2). If calculated per dividing and/or matrix synthesizing cell (cells mainly responsible for the cartilage growth), the cells of the condylar cartilage showed the least growth potency (0.08 mg/cell in comparison to 1.9, 1.5 and 0.3 for epiphyseal, costal, and synchondroseal cartilages, respectively). (AM J ORTHOD DENTOFAC ORTHOP