Abstract
This study describes the distribution of Type I collagen, Type III collagen and fibronectin after periodontal flap operations in rats. Full thickness flaps were raised and the dental roots were surgically exposed. The animals were sacrificed at 1, 3, 4, 5, 7, 14, 28 and 56 days and the wounds were examined using polycronal antibodies. The specimens were fixed in 10% neutral buffered formalin, decalcified with EDTA, made into serial paraffin sections, and also examined. The three following different stainings were done Hematoxylin and eosin. Masson-trichrome and indirect immunofluorescence for the Type I collagen, Type III collagen and fibronectin. After flap operation, fibronectin was detected in the fibrin clot which was negative for Type I collagen and Type III collagen (day 1). Newly formed granulation tissue (3-7 days) stained moderately for Type I collagen, and strongly for fibronectin and Type III collagen. As the number of fibroblasts decreased in the newly synthesized granulation tissue, fibronectin gradually decreased and the amount of Type I collagen increased (14-56 days). On the surgically exposed root dentin surface staining was strongly positive for Type I collagen but negative for Type III collagen. Dense fibrillar networks of Type I collagen and fibronectin were aligned parallel to the exposed root dentin surface, evidence of connective tissue regenerating. Eventually, the regenerated connective tissue fibers stained strongly positive for Type I collagen, negative for fibronectin, and at the site of reattachment of the regenerated collagen bundle was stained positive for Type III collagen (56 days). These results indicate that in the regeneration of connective tissue, the appearance of Type III collagen precedes that of Type I collagen, and functions as an extracellular scaffold for Type I collagen. Fibronectin may be important in theorganization of the collagenous connective tissue. They also suggest that, on the root surface, Type III collagen functions as a scaffold for reattachment.
