Methods: Eight-week old male Wistar rats were used in this study. From 1 day prior to the experiment, BAPN (10 or 40 mg per 100g of body weight) was intraperitoneally injected daily. Excessive occlusal condition was created by applying a 1.2mm thickness metal on the occlusal surface of upper left first molar. After 3 or 7 days of excessive occlusal loading, rats were sacrificed and paraffin embedded histology sections were prepared. Histological changes and collagenous matrix maturation was analyzed by picrosirius red staining observed under a polarized microscope.
Results: In comparison with the normal rats, lathyritic rats showed slight immature collagenous fibers in PDL. In normal rats, excessive occlusal loading induces the maturation of collagenous fibers at the medial side of medial root. However in lathyritic rats, maturation of collagenous matrix did not changed by the excessive occlusal loading. Osteoclast recruitment was induced by excessive occlusal loading at the furcation area of PDL both in the normal and lathyritic rats.
Conclusions: Our study clearly demonstrated that the excessive occlusal loading induced collagenous matrix maturation in PDL but it was not observed in lathyritic animal. These results suggest that mechanical stress accelerate the maturation of collagenous fibers in PDL, at least partially through the collagen cross-linking.