In vitro bonding effectiveness of self-etch adhesives with different application techniques: A microleakage and scanning electron microscopic study

Abstract

Aim: To evaluate and compare the microleakage of self-etch adhesives placed under different clinical techniques and to analyze the resin-dentin interfacial ultrastructure under scanning electron microscope (SEM).

Materials and methods: 100 extracted human premolars were divided into two groups for different adhesives (Clearfil S(3) and Xeno III). Class V cavities were prepared. Each group was further divided into four subgroups (n = 10) according to the placement technique of the adhesive, i.e. according to manufacturer's directions (Group 1), with phosphoric acid etching of enamel margins (Group 2), with hydrophobic resin coat application (Group 3), with techniques of both groups 2 and 3 (Group 4). The cavities were restored with composite. Ten samples from each group were subjected to microleakage study. Five samples each of both the adhesives from groups 1 and 3 were used for SEM examination of the micromorphology of the resin-dentin interface.

Results: At enamel margins for both the adhesives tested, groups 2 and 4 showed significantly lesser leakage than groups 1 and 3. At dentin margins, groups 3 and 4 depicted significantly reduced leakage than groups 1 and 2 for Xeno III. SEM observation of the resin-dentin interfaces revealed generalized gap and poor resin tag formation in both the adhesives. Xeno III showed better interfacial adaptation when additional hydrophobic resin coat was applied.

Conclusions: In enamel, prior phosphoric acid etching reduces microleakage of self-etch adhesives, while in dentin, hydrophobic resin coating over one-step self-etch adhesives decreases the microleakage.

Keywords: Enamel etching; hydrophobic resin coat; microleakage; resin–dentin interfacial micromorphology; self-etch adhesives.

Figure 1

(a) Cross-section of the interface obtained in vitro between CS³ and dentin. Generalized gap can be observed with very few and short resin tags, (b) Cross-section of the interface obtained in vitro between CS³ and dentin with additional hydrophobic layer application showing interfacial gap and absence of resin tags, (c) Cross-section of the interface obtained in vitro between Xeno III and dentin. Generalized gap can be observed with no resin tags, (d) Cross-section of the interface obtained in vitro between Xeno III and dentin with additional hydrophobic resin layer application showing better interfacial adaptation