A STEREOLOGICAL STUDY OF TRABECULAR ARCHITECTURE IN THE MANDIBULAR CONDYLE OF THE PIG

The morphology of bony trabeculae can indicate the loading conditions that predominate near joint surfaces. This study reports principal ori entation, anisotropy, thickness, separation and density of trabeculae in the mandibular condyle of pigs. Condyles from slaughterhouse pigs w ere serially sectioned anteroposteriorly (n = 4), mediolaterally (n = 5) or horizontally (n = 4) at 0.8 mm using a diamond saw. Sections wer e viewed under a stereomicroscope and video-images of four sites per s ection were digitized. Anteroinferior sites had thicker, more widely s paced trabeculae than other sites, suggesting a concentration of stres s. Anisotropy in the frontal plane was greater than in the sagittal or the horizontal planes, indicating a more consistent direction of load ing in the frontal plane. Principal orientation in the frontal section s was perpendicular to the occlusal plane and did not differ among the sites. In the sagittal sections, trabeculae in inferior sites were va riably oriented, whereas those in superior sites sloped posterosuperio rly, possibly reflecting shearing loads resulting from translational m ovements. In the horizontal sections, the trabeculae were oriented per pendicular to the frontal plane, suggesting an anteroposterior compone nt of loading. Compared to cancellous bone from other locations, the t rabeculae of the mandibular condyle are robust and dense, strongly sup porting the notion that the temporomandibular joint is heavily loaded.