Etch & Rinse dental adhesives with hydrophilic solvents are generally influenced by the residual surface moisture in the dentin substrate. Objective: The purpose of this study was to determine the shear bond strength (SBS) of composite to dentin comparing optimal (moist) over-dried and over-wet surface conditions. Methods: Ten specimens each were used to determine composite (TPH3 – Dentsply) to dentin (600 grit surface finish) shear bond strengths after 24 hours of water storage and 1800 thermocycles (5° C-55 °C). Optimal dentin surfaces were created by blotting excess moisture from dentin. Over-wet surfaces were created by applying 25 microliters of water to an isolated 4 mm diameter dentin surface. Over-dried surfaces were created by using a dry air stream for 10 seconds on the dentin surface. Following acid conditioning with 34% phosphoric acid the following adhesive systems were applied to the 3 dentin surface conditions: XP Bond (XP), Excite (E), Optibond Solo Plus (OB), Adper Scotchbond 1(SB) and Syntac Classic (SC). Two-way ANOVA and Tukey's post hoc test were used for data analysis. Results:
| XP | E | OB | SB | SC |
Optimal | 40.6 ± 3.9 a | 38.1 ± 3.2 a | 32.2 ± 3.2 b | 31.8 ± 5.4 b | 26.5 ± 6.6 b |
Dry | 31.7 ± 8.5 b | 24.7 ± 7.4 c | 17.2 ± 7.8 d | 13.5 ± 2.4 d | 24.5 ± 4.8 b,c |
Wet | 32.0 ± 8.9 b | 13.6 ± 4.5 d | 16.7 ± 5.4 d | 20.9 ± 4.8 c,d | 28.7 ± 8.0 b |
Groups connected by a similar letter were statisically similar (p>0.05). Both adhesive system and surface moisture conditions were significant factors (p<0.05). Conclusions: SC was not significantly influenced by the residual surface moisture but generated lower SBS under ideal conditions. SBS of the ethanol systems (E, OB and SB) was influenced more by the over-wet and over-dry conditions compared to XP.