Objective: This study evaluated dentin interfacial microgap in class V composite resin restorations treated with several decontamination methods after saliva exposure during the denting bonding hybridization process,using SEM.

Methods: Standarized class V cavities were made in buccal and lingual surfaces of forty noncarious human molars conditioned with 35% phosphoric acid for 15 seconds and exposed to saliva for 10 seconds. They were then cleaned with different methods, followed by an ethanol - based dentin bonding adhesive system application (Single Bond-3M ESPE) and restored with a microhybrid composite resin (Z250-A2-3M ESPE). The experimental decontamination groups were: Group 1: control group (no contamination); Group 2: cleaned with air for 3 seconds; Group 3: cleaned with water for 10 seconds; Group 4: re-etched with 35% phosphoric acid for 10 seconds. After the specimens were thermocycled for 1000 times, they were fixed in 2.5% glutaraldehide in 0.1M sodium Cacodylate Buffer at 4° and pH 7.4 for 12 hours and then rinsed in 0.2M and pH 7.4 Cacodylate Buffer. The restorations were cross-sectioned, metallurgic polished (#600,800,1200 Grit SiO2 and 2m and 1m diamond suspension), dehydrated with ethanol in increasing concentrations and dryed by mean HMDS. The axial interfaces were observed with a SEM at 1500X.

Results: The analysis of Kruskal-Wallis,showed that there was a difference between groups 1 and 2 with group 4.

Conclusion: After the statistical analysis, hence one can conclude that, saliva does interfere in adhesion process and that air and water cleaning groups presented the best results. It was also observed that the dentin re-etching cleaning treatment presented the highest values of microgap with hybridoid layer formation.

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