Trabecular structure of the condyle of the jaw joint in young and mature sheep: A comparative histomorphometric reference

Abstract

Much of the literature regarding arthrotic changes in the temporomandibular joint (TMJ) is based on the assumption, rather than the demonstration, that joint degeneration is pathologically and biochemically similar to that which has been described for other arthrodial joints. Understanding such changes is axiomatic of an understanding of the specific histomorphometric structure of the normal TMJ, in particular the condyle. Unfortunately, very little has been established about the trabecular bone patterns in the mandibular condyle as it develops. As a consequence of the obvious practical difficulties in investigations of the human TMJ, the sheep has been variously used as an animal model. In order to augment a fuller characterisation of this animal model, this study focuses on the quantitative histomorphometries of the trabeculae in the mandibular condyles of young and mature sheep. Quantitative histomorphometric analyses of condylar trabeculae were performed on histological sections prepared from mature and young sheep condyles. Lateral, central and medial sagittal sections, and anterior and posterior coronal sections of the condyle were analysed using a Quantimet 500MC image analysis system that had been programmed to provide structural index values of trabecular bone volume, surface, thickness, separation and number. Analysis of histoquantitation data revealed a significant concordance in bone structural index values between lateral, central and medial regions in young and mature sheep as well as anterior and posterior regions in young sheep. Moreover, there was little significant variation between similar regions in the respective age groups. This study provides the first comparative histomorphometric quantitative analysis of the trabeculae in the mandibular condyle of both young and mature sheep. The findings of this study reinforce the appropriateness of the sheep TMJ as a model in previous experimental studies of the bony architecture of the condyle.