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 orientation, anisotropy, thickness, separation and density of trabeculae in the mandibular condyle of pigs. Condyles from slaughterhouse pigs were serially sectioned anteroposteriorly (n = 4), mediolaterally (n = 5) or horizontally (n = 4) at 0.8 mm using a diamond saw. Sections were viewed under a stereomicroscope and video-images of four sites per section were digitized. Anteroinferior sites had thicker, more widely spaced trabeculae than other sites, suggesting a concentration of stress. Anisotropy in the frontal plane was greater than in the sagittal or the horizontal planes, indicating a more consistent direction of loading in the frontal plane. Principal orientation in the frontal sections was perpendicular to the occlusal plane and did not differ among the sites. In the sagittal sections, trabeculae in inferior sites were variably oriented, whereas those in superior sites sloped posterosuperiorly, possibly reflecting shearing loads resulting from translational movements. In the horizontal sections, the trabeculae were oriented perpendicular to the frontal plane, suggesting an anteroposterior component of loading. Compared to cancellous bone from other locations, the trabeculae of the mandibular condyle are robust and dense, strongly supporting the notion that the temporomandibular joint is heavily loaded.