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.