Abstract
Marginal adaptation and bacterial penetration were studied in 32 primary molars filled with composite resin in shallow class II cavities. The restorations had served in the mouth for 3 years (mean, 3 years and 4 months; range, 8 months to 6 years and 4 months). Ground sections of the retrieved teeth were evaluated with polarized light microscopy and demineralized sections with light microscopy. Clinically excellent restorations, free from bacteria, were found in 25%. Gaps were recorded in 42%, under- or over-contouring and porosities in 95%, caries in the cervical area in 58%. Bacteria were observed subjacent to the fillings in 75% and in the dentin tubules in 61%. Pupal necrosis was found in 7 of 16 teeth. Marginal discoloration, visible crevice, or color mismatch was associated with marginal defects, bacterial leakage, and pulpal reactions.