Proximo-occlusal composite restorations in primary molars: Marginal adaptation, bacterial penetration, and pulpal reactions

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.