In-vitro evaluation of bond strength of four self-etching cements.

Indirect restorations need to be attached with adhesive luting agents to prevent them from becoming dislodged and provide adequate marginal sealing. The aim of this study was to evaluate bond strength to dentin of self-etching resin cements.

MATERIALS AND METHODS: 75 flat dentin surfaces were randomly distributed among 5 groups, according to cements used; Group 1: RelyxU100 (3M/ESPE), Group 2: Bis Cem (Bisco), Group 3: Max Cem (Kerr), Group 4: SeT PP (SDI) and Group 5: Relyx ARC (3M/ESPE), control. Ceramic test cylinders (IPS Empress 2 / Ivoclar-Vivadent) 4.1 mm across were prepared and attached to the dentin surfaces using the different cements. A constant 25N load was applied for 1 minute and they were light-polymerized. Following storage for 24 hours at 100% humidity and 37 °C, the specimens were tested for bond strength under shear strain in an Instron testing machine at a crosshead speed of 1 mm/minute; at 7, 14 and 21 days. Data were analyzed by ANOVA and Tukey's test. There were significant differences between materials (p < 0.0001), but not between times or material/time interaction. RelyXARC (Control Group) had the highest bond strength (15.52 MPa). Among the self-etching cements, the best behavior was found for Relyx U100 (10.80MPa), followed by BisCem (6.36 MPa), MaxCem (5.45 MPa) and SeTPP (3.17 MPa). The bond strength of the self-adhesive cements evaluated was lower than that for resin cements which require previous treatment of the dental substrate (control group). This should be taken into account during clinical selection, in particular for tooth preparations with poor retention.