Effect of air-drying temperature on the effectiveness of silane primers and coupling blends in the repair of a microhybrid resin composite.
OBJECTIVE
To evaluate the effect of different silane agents and air-drying temperatures on the repair strength of a microfilled hybrid composite.


METHODS
Composite cylinders (8 x 4 mm) of Gradia Direct Anterior (GC, N=36), stored in a saline solution at 37 degrees C for 1 month, were sandblasted (50-microm aluminium oxide), cleaned (35% phosphoric acid) and randomly divided into six groups (n=6). Two prehydrolyzed silane primers (Monobond-S, Ivoclar-Vivadent, Porcelain Primer, Bisco), a non prehydrolyzed silane primer (Porcelain Liner M, Sun Medical) and three silane/adhesive coupling agents (Porcelain Bond Activator-PBA/Clearfil New Bond, PBA/Clearfil SE Bond, PBA/Clearfil Tri-S Bond, Kuraray) were investigated. Silane-coated surfaces were air dried at two different temperatures (23 degrees C and 38 degrees C) and repairs (8 x 8 mm) were fabricated (Gradia Direct Anterior). Unrepaired composite cylinders (8 x 8 mm, n=6) were used as control to evaluate the cohesive strength of the material. Microtensile bond strength measurements (microTBS) were performed.


RESULTS
The silane agent applied (p < 0.001), the airdrying temperature (p < 0.001) and their interaction (p < 0.001) were significant factors (two-way ANOVA, Tukey test; p < 0.05). Silane primers achieved inferior microTBS when air dried at 23 degrees C as compared to silane/adhesive blends. Warm air-drying was significantly beneficial to composite repairs mediated by silane primers. Comparable results were achieved by silane/adhesive couplings at 23 degrees C and 38 degrees C. At 38 degrees C all the intermediate agents resulted in repair microTBS that were comparable to the 24-h cohesive strength of the composite (one-way ANOVA, Dunnett t-tests; p < 0.05).


CONCLUSIONS
The chemical interactions between silane primers and compozite substrate may be optimized through warm airdrying. Silane/adhesive couplings were not influenced by the air drying temperature.
Papacchini
Federica
F
Department of Dental Materials and Restorative Dentistry, University of Siena, Policlinico Le Scotte, Siena, Italy.
Monticelli
Francesca
F
Hasa
Irida
I
Radovic
Ivana
I
Fabianelli
Andrea
A
Polimeni
Antonella
A
Ferrari
Marco
M
D000180:Acrylic Resins / Q000737:chemistry*; D000388:Air; D003188:Composite Resins / Q000737:chemistry*; D017269:Dental Prosthesis Repair / Q000379:methods*; D006358:Hot Temperature; D011140:Polyurethanes / Q000737:chemistry*; D012821:Silanes / Q000737:chemistry*; D013718:Tensile Strength
D000180:Acrylic Resins; C029012:Composite Dental Resin; D003188:Composite Resins; D011140:Polyurethanes; D012821:Silanes