Effect of condylotomy on matrix synthesis and mineralization in the rat mandibular condylar cartilage

Condylotomy to Reverse Temporomandibular Joint Osteoarthritis in Rabbits

PURPOSE

Osteoarthritis (OA) of the temporomandibular joint (TMJ) is characterized by local tissue degeneration and pain. Treatments have been aimed at reducing symptoms, and only some can interfere with the progression of pathophysiologic changes caused by OA. Condylotomy is an alternative treatment for patients with OA refractory to conventional treatment. The aim of the present animal study was to investigate the influence of condylotomy on TMJ OA in New Zealand rabbits.

MATERIALS AND METHODS

The 36 rabbits were divided into 3 groups: the osteoarthritis group (OG; induced OA), treatment group (TG; induced OA plus condylotomy), and control group (CG; neither OA nor surgery). OA was induced using intra-articular monosodium iodoacetate injection for 40 days. The rabbits in the TG underwent condylotomy and were killed 20, 40, and 60 days after treatment. The rabbits in the CG and OG were killed at the same points.

RESULTS

The articular joint condition was better in the TG 60 days after surgery (P = .032). A direct comparison revealed regression of TMJ OA over time among the treated rabbits (P = .008). Surgical treatment promoted mandibular condylar remodeling in the TG, reversing the tissue degeneration caused by OA.

CONCLUSIONS

Our findings suggest that condylotomy could be an option for the treatment of OA and prevent damage to TMJ structures. This could be of particular importance for patients without satisfactory responses to more conservative treatment.

Hydrostatic Compress Force Enhances the Viability and Decreases the Apoptosis of Condylar Chondrocytes through Integrin-FAK-ERK/PI3K Pathway

Reduced mechanical stimuli in many pathological cases, such as hemimastication and limited masticatory movements, can significantly affect the metabolic activity of mandibular condylar chondrocytes and the growth of mandibles. However, the molecular mechanisms for these phenomena remain unclear. In this study, we hypothesized that integrin-focal adhesion kinase (FAK)-ERK (extracellular signal-regulated kinase)/PI3K (phosphatidylinositol-3-kinase) signaling pathway mediated the cellular response of condylar chondrocytes to mechanical loading. Primary condylar chondrocytes were exposed to hydrostatic compressive forces (HCFs) of different magnitudes (0, 50, 100, 150, 200, and 250 kPa) for 2 h. We measured the viability, morphology, and apoptosis of the chondrocytes with different treatments as well as the gene, protein expression, and phosphorylation of mechanosensitivity-related molecules, such as integrin α2, integrin α5, integrin β1, FAK, ERK, and PI3K. HCFs could significantly increase the viability and surface area of condylar chondrocytes and decrease their apoptosis in a dose-dependent manner. HCF of 250 kPa resulted in a 1.51 ± 0.02-fold increase of cell viability and reduced the ratio of apoptotic cells from 18.10% ± 0.56% to 7.30% ± 1.43%. HCFs could significantly enhance the mRNA and protein expression of integrin α2, integrin α5, and integrin β1 in a dose-dependent manner, but not ERK1, ERK2, or PI3K. Instead, HCF could significantly increase phosphorylation levels of FAK, ERK1/2, and PI3K in a dose-dependent manner. Cilengitide, the potent integrin inhibitor, could dose-dependently block such effects of HCFs. HCFs enhances the viability and decreases the apoptosis of condylar chondrocytes through the integrin-FAK-ERK/PI3K pathway.

Changes in temporomandibular joint after mandibular subcondylar osteotomy: an experimental study in rats

The objective of this study was to analyze the changes in the different components of the temporomandibular joint and their relation with age after subcondylar osteotomy. For this purpose 149 Wistar rats were divided into three groups: osteotomy, sham operation, and control. Two experimental ages (30 and 70 days) and radiologic, morphometric, macroscopic, and histologic methods of analysis were used. Different changes were observed in young and adult animals. Subcondylar mandibular osteotomy in growing rats caused anteroinferior displacement of the temporal and mandibular component of the joint. At the end of the experimental period only condylar displacement was maintained. Other changes were flattening of the mandibular condyle, which was transient, and lateral thickening of the articular disc. Subcondylar mandibular osteotomy in adult rats caused slight anterior displacement of the joint components at the end of the experimental period. At this age, although changes similar to those in growing animals were observed in some cases, in other cases the presence of pathologic findings, such as deformation of the condylar cartilage, thickening of the disc, intra-articular adherences, and osteolysis of the temporal fossa, were observed. Changes in the joint components were more marked in growing rats than in adults. In growing rats they affected the form of the condylar process to a greater extent, but the majority of these changes were transient. In adult rats, alterations in the joints were less pronounced, but they affected a greater number of joint components and were permanent.