This study evaluated the in vitro early marginal seal effectiveness in class V restorations of glass ionomer cement with or without dentin treatment, sandwich technique, and composite resin with several kinds of dentin bonding agents. The preparations were as uniformly as possible, with depth 1.5 mm, size 4 X 3mm. The one kind of glass ionomer cement for each type, 40% polyacrylic acid for dentin treatment, one kind of composite resin and three commercial dentin bonding agents were tested.
Four groups were restored with only glass ionomer cement to evaluate the effect of dentin treatment and the type of glass ionomer on marginal leakage. Two groups were filled with composite resin with glass ionomer base by means of sandwich technique. And three groups were restored wih three commercial dentin bonding agent(Gluma®, Scotchbond 2®, and Tenure) and composite resin. The one that was filled with composite resin without use of dentin bonding agent was used as control group. Ten experimental groups including control group were established and each group had ten cavities. Eight of ten cavities of each group were used for marginal leakage test and two of ten, for investigation of marginal gap.
Immediately after being restored, all of specimens were thermocycled 100 times through water bath of 5 ± It and 55 ± It for 38 sec in each bath. Then, marginal leakage of them were estimated by dye penetration method and scanning electron micrographs were taken to evaluate the marginal gap between dentin and restorations at X 1,000 magnification.
On the summary of this study, the conclusions were as follows
1. Generally, more marginal leakage at the gingival margins was investigated than at the occlusal margin. While the groups filled with composite resin with dentin bonding agents showed less marginal leakage at occlusal margin, the groups restored with glass ionomer cement had the lower marginal leakage score at gingival margin.
2 When glass ionomer/composite resin sandwich restorations were compared with other restorations, they had least margial leakage at gingival margin.
3. Types of glass ionomer cement and dentin treatment did not affect on the marginal leakage at occlusal margin. At gingival margin, marginal leakage of light curing glass ionomer cement with dentin treat-merit showed significantly higher marginal leakage and wider marginal gap was seen in light curing glass ionomer cement than in chemical curing glass ionomer cement.
4. Though Tenure® exibited significantly less marginal leakage than Gluma® and Scotchbond 20, all of three dentin bonding agents seldom made wide marginal gap equally.
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