Objectives: To test the hypothesis that previous etching with 37% PA improve bond strength and durability of bonds made with Clearfil SE Bond (SE, Kuraray) and One Up Bond F (OUB, Tokuyama) to ground enamel. Methods: Buccal and lingual enamel of human third molars were ground wet with coarse diamond bur. The adhesives were applied either according to manufacturer’s instructions (20s, CG) or after pre-etching enamel with 37% PA for 10s (EG). Bonded teeth were stored for 24h at 37ºC, sliced and trimmed to a dumbell-shape with a cross-seccional area of 0.8 mm2. The specimens were stored either in water (W) or mineral oil (O) for 24h, 6 months (6M) and 1 year (1Y). After each storage period, specimens were tested in microtensile at 0.5mm/min. Results: Values are MPa ± SD(N). Capital letters compare each condition as a function of time and storage medium (row). Lower cases compare each material as a function of etching within each storage condition (column).
|
Material |
24h |
6MW |
1YW |
6MO |
1YO |
|
SE (CG) |
30,5±8,3Aa (10) |
22,4±6,3Bb (8) |
23,7±11,0Bb (10) |
30,6±8,2Aa (6) |
32,5±10,5Aa (9) |
|
SE (EG) |
38,5±11,1Aa (7) |
31,4±8,1Aa (9) |
37,9±14,4Aa (11) |
29,6±10,6Ba (8) |
35,5±6,3Aa (6) |
|
OUB (CG) |
17,5±6,0Ac (8) |
23,7±7,5Ac (12) |
18,4±4,8Ac (9) |
19,7±8,4Ac (7) |
30,3±5,5Bc (7) |
|
OUB (EG) |
41,3±7,5Ad (9) |
27,5±10,5Bc (9) |
26,6±6,8Bd (11) |
39,5±9,8Ad (7) |
48,6±11,2Ad (8) |
Multiple-way ANOVA showed that the effect of etching and storage was dependent on the material. Pre-etching with PA improved immediate bond strength for OUB (p<0.05), but not to SE (p>0.05). Pre-etching resulted in sustained bond strength of SE after water storage (p>0.05), but not for OUB (p<0.05) after water storage. Specimens stored in oil maintained bond strength over time (p>0.05). Conclusion: The effects of pre-etching ground enamel with 37%PA on the bond strength and durability of the bonds made with self-etching adhesives are material dependent.