Adaptation of composite fillings to cavity walls in three different cavities.

Adaptation of eight kinds of resin restorations on Class V enamel cavity, cement-enamel-junction (CEJ) cavity and root surface cavity were compared. Extracted human premolars were used as experimental specimens. Restored specimens were divided into two groups; short storage group of 2 week duration and long storage group of 6 month duration. The specimens were thermal cycled during storage. After that replicas of the vertical sections were made for examination by SEM and the gaps measured from photographs. The appearance and width of gaps between resin and cavity walls were characterised by the type of cavity and the filling materials. In Class V enamel cavity, gaps were observed on the cavity floor, whilst almost none was observed in other areas showing good adaptation. In the CEJ cavity, gaps appeared only at the cavity floor and gingival wall. In the root surface cavity, gaps were observed on all cavity walls with smaller widths on the occlusal wall and greater width on the cavity floor. Clearfil-F and Clearfil-F II showed fine adaptation on all cavities in general, especially on the dentinal cavity wall. Almost all the materials showed a tendency to form gaps which was found to increase with time. The difference in width, however, varied with the materials used.