Scanning Microscopy


The interface between a composite resin restoration and dentin is still a problem with regard to secondary caries and esthetics. With conventional restorative techniques the absence of bonding between the restorative material and the dentin produces marginal gaps. These gaps are populated with microorganisms or trap pigments. Therefore, adhesive techniques are required for functional and esthetic restorations.

In extracted teeth stored in 0.1% thymol solution, 8 cylindrical cavities (diameter: 3 mm; depth: 2 mm) and 8 class V cavities (1/2 of the margin in dentin) were prepared in each group and filled with composite resin. Before actual placement the following dentin adhesives were used: Scotchbond 2 (3M), Gluma (Bayer), Scotchbond LC (3M), Dentin Adhesit (Ivoclar), Dentin Adhesive (Kulzer) and Durafill-Bond (Kulzer) as a control. Before and after thermocycling (TC) (2000 cycles, 5° C to 55° C) replicas were taken and a quantitative margin analysis in the SEM was performed at 200 x magnification. To analyze the data, a rating scale (four criteria) was used to characterize the marginal configuration. Statistical analysis of the results showed that the materials Gluma, Scotchbond LC and Scotchbond 2 yielded significantly (p < 0.05) better margins than the other materials in both cylindrical and class V cavities. Before TC values > 90% were found with Gluma, Scotchbond LC and Scotchbond 2 in Class V cavities. However, after TC, these values decreased significantly to 66% for Gluma, 42% for Scotchbond LC and 81% for Scotchbond 2. Scotchbond 2 showed approximately 80% excellent margins in both cavity forms after TC.

A subsequent clinical study should be done to confirm these favourable results in vivo.

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