Effect of pre-cure temperature on the bonding potential of self-etch and self-adhesive resin cements

Abstract 

Objectives

To assess whether the pre-cure temperature of resin cements significantly influenced the bonding potential to dentin.

Methods

Forty extracted molars were randomly divided into 8 groups (n=5): Groups (1–4) RelyX Unicem (RU, 3M ESPE) and Groups (5–8) Panavia F 2.0 (PF, Kuraray Co.), at pre-cure temperatures of 4, 24, 37, and 60°C, respectively. Cements were used in dual-cure mode for luting composite overlays (Paradigm MZ100, 3M ESPE) to dentin. Microtensile bond strength testing and scanning electron microscope (SEM) observations of cement–dentin interfaces were performed.

Results

Group 4 had to be eliminated as RU at 60°C underwent such an accelerated curing that was already set at the time of dispensing. The bond strengths (MPa) measured at refrigerator, room, and intraoral temperature were, respectively: RU 5.4±1.7, 11.4±6.1, 10.6±4.2; PF 7.4±3.7, 13.9±6.2, 12±5.2. The statistical analysis revealed that both luting agents developed a significantly weaker adhesion when used at refrigerator temperature (p<0.05). No statistically significant differences in bond strength were recorded when either cement was used at 24 or 37°C (p>0.05). Pre-heating of PF to 60°C resulted in a significant increase in bond strength (20.7±9.4MPa; p<0.05). SEM observations disclosed an enhanced potential of PF to form a hybrid layer as the temperature increased over 4°C. RU exhibited a less porous and more homogeneous layer at intraoral than at refrigerated temperature.

Significance

It is advisable to let refrigerator-stored resin cements warm up to at least room temperature prior to clinical use. Pre-heating to 60°C enhances the bonding potential of PF.

Keywords: Pre-cure temperature, Pre-heating, Resin cement, Adhesion, Dentin