Biocompatibility test of hard-setting cements employing the implantation method

Objective: Evaluate the biocompatibility of three different hard-setting cements when implanted into subcutaneous tissue of rats. Methods: Forty-five polyethylene tubes were autoclaved and filled with the experimental dental materials which were hand-mixed according to the manufacturer’s instructions: Group 1: Mineral Trioxide Aggregate (Pro Root – MTA, Dentsply); Group 2: Calcium Hydroxide (Dycal – Dentsply), and Group 3: Zinc Oxide and Eugenol (ZOE - Dinâmica). The tubes containing the cements were implanted into surgical pockets prepared in the dorsal subcutaneous tissue of rats. Empty polyethylene tubes were used as control group. After 15, 30 and 90 days, the implants were surgically removed, fixed for 48 hours in buffered formalin and processed using routine histologic techniques. Sections of 6 mm were stained with hematoxylin and eosin and evaluated under light microscopy. Results: At short-term evaluation, the connective tissue adjacent to MTA and Dycal exhibited discrete inflammatory reaction associated to thin fibrous capsule. On the other hand, ZOE elicited moderate inflammatory reaction and thicker capsule formation. Connective healing was observed for all experimental groups over time. MTA and Dycal allowed complete healing at the 30-day evaluation while it was observed to ZOE only at 90 days after the implantation procedure. In control group, connective healing related with fibrous capsule was seen at 15-day evaluation. Conclusion: According to the experimental conditions it was concluded that all experimental dental materials are biocompatible. However, ZOE is more irritant to the connective tissue of rats than MTA and Dycal.