TIME-RELATED DEVIATIONS OF FIBRONECTIN AND TYPE-I, TYPE-II AND TYPE-III COLLAGEN ON THE INTERFACE BETWEEN A HYDROXYAPATITE DISC AND THE RIMOF A CALVARIAL TREPHINE DEFECT IN RABBITS

To pursue the events around hydroxyapatite (HA) discs (diameter 9 mm), implanted in calvarial defects in rabbits (diameter 11 mm), immunohis tochemical changes of fibronectin and type I, II and III collagen were quantitatively determined in the connective tissue-HA (CTHA) and host bone-HA (BHA) interface at 8, 12 and 16 wk postimplantation. A marked enhancement of type I collagen staining in the BHA interface was note d at the 12th and the 16th wk in comparison to the CTHA interface and connective tissue in the untreated control defect. However, one of the characteristics of the staining in the CTHA interface was the finding of exceptionally high fibronectin and type III collagen at the 8th an d the 12th wk in contrast to the BHA interface and the untreated contr ol defect. The change in these immunohistochemically determined compos itions was probably due to an active proliferation of vascular compone nts in the CTHA interface. Bone regeneration in the CTHA interface was parallel to an increase in type I collagen and a decrease in fibronec tin and type III collagen from 8 to 16 wk. This study indicated that v ariances in composition or characteristics of connective tissue in CTH A interface have taken place ahead of bone morphogenesis. The time-rel ated derivation of connective tissue matrix components in the BHA and CTHA interface was confined to the interaction of implanted HA with ho st tissues in contact with the implant. (C) 1996 Elsevier Science Limi ted.