Unilateral Masticatory Function Changes the Proteoglycan Content of Mandibular Condylar Cartilage in Rabbit

Abstract

Unilateral masticatory function was induced in 10-day-old rabbits by grinding the right side molars out of occlusion under general anesthesia. The grinding procedure was repeated twice a week thereafter. They were killed at the ages of 25 and 35 days. Rabbits of the same age with uninterfered occlusions served as controls. The changes in articular cartilage of the mandibular condyle were studied biochemically and histochemically. There was a significant decrease in the proteoglycan content of the condylar cartilage in both groups of animals subjected to molar grinding compared to the animals with untouched occlusions. Especially the amount of aggregating proteoglycans was reduced. The condylar cartilage matrix synthesis is sensitive to loading produced by masticatory function during growth. The mechanical properties of the articular cartilage after a period of unilateral mastication will be impaired and it is possible that this makes the joint cartilage more susceptible to pathological events.

Deletion of Runx2 in condylar chondrocytes disrupts TMJ tissue homeostasis

“…The primary proteoglycan in TMJ condylar cartilage is negatively charged aggrecan, capable of binding with a hyaluronic chain to form large aggregates (Poikela et al, 2000). It is known that aggrecan is mainly located in the hypertrophic and mature zones (Roth et al 1997, Mao et al 1998).…”

Biomechanical properties of the mandibular condylar cartilage and their relevance to the TMJ disc

“…The model, age, gender and weight are all among well-known important animal selection parameters that can indirectly affect the biomechanical properties. In addition to these, the loading history of the subject tissues is another factor that may alter the biomechanical properties of the tissues, as the condylar cartilage is known to undergo adaptation and remodeling following the changes in the stress-fields over the condyle (Copray et al, 1985;Kantomaa and Pirttiniemi, 1998;Poikela et al, 2000;Shen et al, 2006;Teramoto et al, 2003;Xiong et al, 2005). Apart from animal selection, another important issue is the mode of testing-in vitro or in situ?…”

Biomechanical evaluation of the equine masticatory action: Calculation of the masticatory forces occurring on the cheek tooth battery

“…The teeth are responsible for sufficient feed intake and-even more critical-proper disruption, thus preparing the low-nutrient foliage for further digestion (Frape, 1990;Meyer and Coenen, 2002). The forces generated during equine mastication also have an effect on the tooth and on materials used in dental therapy, as well as on the periodontal ligament, and-last but not least-excessive masticatory force have an pathologic effect on the condylar cartilage of the temporomandibular joint (Poikela et al, 2000).…”