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.