Experimentally Induced Unilateral Tooth Loss: Histochemical Studies of the Temporomandibular Joint

Abstract

Occlusal abnormality may contribute to osteoarthrosis of the temporomandibular joint (TMJ). Since mechanical force may induce changes in the extracellular matrix, we tested the hypothesis that unilateral removal of teeth and the resulting unilateral mastication change the content of glycosaminoglycans (GAGs) in the TMJ condyle and disc. Lower-right-side teeth were extracted from 12 adult male rabbits, which were killed 3 or 6 weeks later. Three normal rabbits served as controls. Sections were analyzed for morphological changes and levels of sulfated GAGs in the condyle and disc. Unilateral removal of teeth led to thickening of the condylar cartilage, alterations in the morphology of chondrocyte nuclei in the condylar cartilage and disc, and increases in levels of negatively charged ions in the hypertrophic layer of condylar cartilage. Small differences were observed, after unilateral removal of teeth, between the functional and non-functional sides of the TMJ. The results suggest that in response to mechanical stress, chondrocytes alter sulfated glycosaminoglycan (GAGs) synthesis and degradation rates, resulting in an elevated level of sulfated GAGs in the condylar cartilage.

Death and proliferation of chondrocytes in the degraded mandibular condylar cartilage of rats induced by experimentally created disordered occlusion

“…OA is characterized by the slow, progressive degradation of articular cartilage, which includes marginal proliferation, early loss of proteoglycan, and fibrillation [3]. Although the etiology of TMD is generally considered to be multifactorial, one likely candidate is the overloading of the TMJ stemming from occlusal abnormalities [4,5]. Numerous studies on condylar cartilage in different animal models have been reported [5][6][7].…”

“…Although the etiology of TMD is generally considered to be multifactorial, one likely candidate is the overloading of the TMJ stemming from occlusal abnormalities [4,5]. Numerous studies on condylar cartilage in different animal models have been reported [5][6][7]. The histological changes seen in the immediate response to artificial abnormal occlusion have most commonly included the thickening of the condylar cartilage [5], hyperplasia and alterations in the morphology of chondrocytes [5,6], changes in the proliferation and maturation of chondrocytes [7], and an elevated level of sulfated glycosaminoglycans [5,7].…”

Volumetric and morphologic changes due to effect of unilateral extraction of teeth

“…Huang et al, found a significant increase of the histological glycosaminoglycan levels in the tissues of the mandibular condyle and articular disc in rabbits after tooth extraction. As a result of this, growth of the mandibular condyle and articular disc were seen [4]. We used only measurements in our study.…”

“…In previous studies, it has been proposed that a reaction may occur after the occlusal alterations in response to the new distribution of loading, and bone tissues in the mandibular condyle may be altered [3,4]. Studies in humans and rats showed disturbance of the local microcirculation, irregular fibers in the disc, smaller and condensed chondrocytes in the condylar cartilage, and destruction of articular cartilage of the TMJ [5,6].…”

Primate Craniofacial Function and Biology

“…Histological and immunohistochemical analysis of symphyseal and TMJ tissues followed standard methods (Scapino, 1981;Trevisan & Scapino, 1976a, b;Hirschfeld et al, 1977;Bouvier & Hylander, 1982Bouvier, 1987Bouvier, , 1988Kiernan, 1999;Huang et al, 2002;Kim et al, 2003; a joint was dehydrated in a graded concentration series of ethanol baths, washed in xylene, and then embedded in paraffin. Special care was exercised to maintain joint, and thus section, orientation parallel to the surface of the paraffin block.…”