Application methods influence on self-etching adhesive systems enamel bond strength

Objectives: The aim of this study was to evaluate the effectiveness of technique variations regarding application method on enamel bond strength of self-etching adhesive systems. Methods:130 bovine teeth divided in 13 groups were used, each one receiving different application methods and adhesive systems. The following adhesive systems were studyed: One Up Bond F (OU), ClearFil SE Bond (CB), Self & Etch (SE) and acid conditioning + Magic Bond conventional adhesive as a control group (GC). The enamel surface was polished using a 600-grit sandpaper. An adhesive tape with a 3mm diameter perforation was used in order to delimitate the adhesion area. One or two layers of adhesive, in an active (A) or a passive (P) way, were applied. Resin cylinders with 3mm in diameter were manufactured in two steps, each increment photo-cured by 40''. The samples were stored in distiled water at 37ºC by 24h and then submitted to shear test. The ANOVA and Tukey's statistic tests were applied. Results:The ANOVA showed p=0,00. The bond strength means (± standard deviation) found were:SE2P- 5,32 (± 3,12)a; SE1P- 5,53 (± 2,81)a; SE1A- 5,95(± 3,54)a; CB2P- 7,05 (± 4,03)ab; OU2P- 8,08 (± 2,93)ab; CB1A- 8,62 (± 3,38)ab; SE2A- 9,53 (± 4,41)abc; OU1P- 9,80 (± 3,98)abc; CB1P- 10,62 (± 3,75)abc; OU1A- 12,04 (± 3,50)bc; CB2A- 14,61 (± 2,64)cd; OU2A- 18,74 (± 5,51)d; GC- 19,03 (± 5,22)d. The means followed by common letters showed no significant difference. Conclusions: It has been concluded that the application of two layers in an active way resulted in a significant increase of bond strength when compared to one layer in a passive way. Both OU2A and CB2A promoted a bond strength similar to GC.