Marginal adaptation of compomers in Class I and V cavities in primary molars

To evaluate in primary molars (1) the adaptation of three compomers in Class I and V cavities at the cavosurface margins and inside the cavity, and (2) the effect of cavity etching on such adaptation.

The three compomers used were Compoglass, Dyract and Hytac. Sixty exfoliated primary molars were divided for the three compomers, which were subdivided into Class I and V (10 each) and subdivided again into etched and non-etched (5 each). Standard Class I and Class V cavities with the gingival margins at cementum were prepared. The cavities were restored with the three compomers used with or without etching the cavity. The restored cavities were finished and polished. The cavosurface margins were inspected under the light microscope. Then the restored teeth were sectioned into two halves. The cut halves were fixed in glutaraldehyde and the cut surfaces smoothed, polished and inspected under the light microscope for adaptation of the restorative material inside the cavities. One halve of each molar was prepared for SEM.

The three compomers showed good adaptation at the cavosurface margin except the non-etched Class V cavities restored with Dyract. Compoglass and Dyract were well adapted inside the cavity better than Hytac. Cavity angles were common sites for adhesive pooling for all materials. SEM examination showed good adaptation of the restorative at enamel and cementum interface especially in etched cavities. The dentin-restorative interface showed consistent hybrid layer with resin tags in the etched cavities. However this layer was inconsistent in the non-etched cavities.