Effect of dental film on adhesive bond strength to enamel using different adhesive systems

ABSTRACT

The purpose of this study was to evaluate the effect of the dental film, forme in vitro, on the adhesive bond strength of resins to enamel. Fragments of previously planed bovine enamel were submitted to different periods of time in contact with human saliva, to form dental film (1, 12 and 24 hours). Next, the following adhesive systems were used Scotchbond Multi-Purpose (3M ESPE, Brazil), and Clearfil SE Bond (Kuraray, Osaka, Japan) and over them an approximately 4 mm thick layer of composite resin Z100 (3M ESPE, Brazil)was constructed. After 24 hours of storage, the specimens were sectioned to obtain sticks with a cross sectional area of approximately 1 mm², which were submitted to microtensile tests in an Instron testing machine. Statistical analysis of the results, by means of the ANOVA and Tukey tests showed similarities between salivary contact periods using the Clearfil SE Bond (p=0.108) adhesive system. For the Scotchbond Multi-Purpose adhesive system, the ANOVA and Dunnett tests detected statistically significant differences between the 1 and 12 hour groups (p=0.010), between 1 and 24 hour groups (p=0.003), and between the 1 hour and control groups (p=0.021). Comparing the two adhesives used, the Student-t test detected similarity between adhesive bond strength values obtained at different periods of salivary contact and the two systems tested. Adhesive failure was the most frequent type of fracture observed in both systems used, in the 12 hours and 24 hours groups. Cleaning procedures prior to the application of the adhesive systems to enamel are indicated.