Effect of pre-cure temperature on the bonding potential of self-etch and self-adhesive resin cements.
OBJECTIVE
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, 3 M ESPE) and Groups (5-8) Panavia F 2.0 (PF, Kuraray Co.), at pre-cure temperatures of 4, 24, 37, and 60 degrees C, respectively. Cements were used in dual-cure mode for luting composite overlays (Paradigm MZ100, 3 M 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 degrees 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 degrees C (p>0.05). Pre-heating of PF to 60 degrees C resulted in a significant increase in bond strength (20.7+/-9.4 MPa; p<0.05). SEM observations disclosed an enhanced potential of PF to form a hybrid layer as the temperature increased over 4 degrees C. RU exhibited a less porous and more homogeneous layer at intraoral than at refrigerated temperature.


CONCLUSIONS
It is advisable to let refrigerator-stored resin cements warm up to at least room temperature prior to clinical use. Pre-heating to 60 degrees C enhances the bonding potential of PF.
Department of Dental Materials, University of Siena, Siena, Italy.
Amerigo
A
Cantoro
Cecilia
C
Goracci
Federica
F
Papacchini
Claudia
C
Mazzitelli
Giovanni Maria
GM
Fadda
Marco
M
Ferrari
D003080:Cold Temperature; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003804:Dentin / Q000648:ultrastructure; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D006358:Hot Temperature; D006801:Humans; D007284:Inlays; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D019279:Resin Cements / Q000737:chemistry*; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013718:Tensile Strength; D015040:Zirconium / Q000737:chemistry
D003188:Composite Resins; D017220:Dentin-Bonding Agents; C438843:Panavia-Fluoro; C483701:Rely X Unicem; D019279:Resin Cements; C452079:paradigm MZ100; D015040:Zirconium