Restorative pulpal and repair responses

Background. Each year, about 90 million new restorations are placed in the United States and 200 million are replaced. Controversy surrounds the pulpa l reactions and frequency of bacterial microleakage associated with common restorative materials. The authors investigated and compared pulpal reactio ns to different types of restorative materials. Methods. Two hundred seventy-two teeth with standardized rectangular Class V unexposed cavities were restored with resin-based composite bonded to den tin; resin-based composite bonded to enamel; resin-modified glass ionomers, or RMGI; amalgam lined with zinc polycarboxylate, or ZnPC; amalgam lined w ith calcium hydroxide, or Ca(OH)(2); or zinc oxide-eugenol, or ZnOE. Teeth were extracted for orthodontic reasons between 20 and 381 days later. The a uthors categorized pulpal responses according to standards set by the Feder ation Dentaire Internationale and the International Organization for Standa rdization. Bacteria were detected using Brown-Brenn-stained sections. Pulpa l responses were evaluated using histomorphometric analysis and analysis of variance statistics. Results. The results showed that RMGI was the best material for preventing bacterial microleakage, and resin-based composite bonded to enamel was the worst. In regard to minimizing pulpal inflammatory activity, ZnOE was the b est material and resin-based composite bonded to enamel was the worst. In t erms of maximizing odontoblast survival beneath deep cavity preparations, C a(OH)(2), was the best material and RMGI was the worst. Conclusions. The results show that bacterial microleakage, pulpal injury an d repair responses varied widely with different restorative materials. Clinical Implications. The authors recommend that RMGI be used to restore t eeth with cavities that are shallow to moderate in depth, with the floor of deep cavities being lined with Ca(OH)(2) before the teeth are restored wit h RMGI.