Marginal gap formation in the composite resin/glass ionomer cement Class V restoration

The purpose of this study was to assess marginal gap formation in Class V restorations using 2 dentin bonding agents (DBA) and 7 different cavity filling methods. Two glass ionomer cements (GIC) were used: Ketac-Bond (KB) and Ketac-Fil (KF). Class V cavities were prepared, one-half in enamel and one-half in dentin, in extracted human teeth. There were 2 control (no GIC used) and 12 experimental groups with 10 restortions each. Seven groups were evaluated with Scotchbond Lightcure (S) and 7 with Prisma Universal Bond (P). For each DBA the KB was applied as a 0.5 mm layer in 2 of the groups. In one of these the cement was etched with 35% H₃PO₄ for 30 s. For each DBA the KF was applied either in bulk, leaving the margins exposed (2 groups), or the cavities were filled, and then cut back after 24 h, exposing the margins (2 groups). The KF was etched in 2 of these 4 groups with 35% H₃PO₄ for 30 s. In all cases the enamel was beveled and etched. All cavities were filled with Silux. Basic fuchsin dye was used to detect marginal gaps. Each restoration was photographed, traced, and scored for marginal gaps as 0 or 1 at 5 enamel and 5 dentin locations. Gaps were present in 6.6% of all enamel locations and in 92% of all dentin locations. The effect of methods and DBA on marginal leakage at the enamel and dentin locations was assessed by two-way analysis of variance. There were significant differences between methods for enamel (p<0.01) and for dentin (p<0.005). The leakage scores for S were significantly greater than P in enamel (p<0.005) and in dentin (p<0.025). Although there were statistically significant differences among methods and between DBA, these differences are considered to be of little or no clinical significance because there were so few enamel marginal gaps while dentin marginal gaps were present in almost all the cases.