Biocompatibility of two current adhesive resins

The purpose of the study was to evaluate the biocompatibility of two curren t adhesive resins and a calcium hydroxide cement. Fifty-four polyethylene t ubes were filled with these dental materials, which were hand-mixed or ligh t-cured according to the manufacturer's directions: group 1-Clearfill Liner Bond 2 (Kuraray); group 2-Single Bond (3M); and group 3-calcium hydroxide cement (Dycal-Dentsply). The materials were implanted into dorsal connectiv e tissue of rats, which were killed 7, 30, and 60 days after the implantati on procedure. The implant sites were excised, immersed in buffered Karnovsk y's fixative, and processed using routine histological techniques. Sections of 6 mu m thickness were stained with hematoxylin and eosin and assessed u nder light microscopy. Both adhesive resins at 7 days elicited a moderate/i ntense inflammatory reaction that decreased over time. Fibrous capsules sur rounding the tubes were observed at 30 days. Half of the samples in groups 1 and 2 showed thin fibrous capsule formation containing macrophages, capil laries, lymphocytes, fibroblasts, and collagen fibers. Connective tissue he aling was observed even though many specimens exhibited a persistent inflam matory reaction mediated by macrophages and giant cells at the 60-day evalu ation. Dycal allowed complete healing at 30 days with only a thin fibrous c apsule. In conclusion, all experimental materials were successfully walled off by the connective tissue of the rat. However the adhesive resins may re lease particulates that may, in turn, induce a persistent local inflammator y reaction. Consequently, in this specific condition, these materials canno t be regarded as biocompatible. Dycal was less irritating than the adhesive resins and was better tolerated by the connective tissue.