Purpose: To test the hypotheses that microtensile bond strengths of single-step, self-etch adhesives to hydrated dentin are adversely affected by delayed-activation of a light-cured composite, as well as the use of a chemical-cured composite. Methods: Seven commercially available and one experimental single-step, self-etch adhesives were bonded to hydrated human dentin. A dual-cured composite was used and activated using:  the light-cured mode (base paste only - control),  the chemical-cured mode (base and catalyst pastes, in the dark); and  delayed light-activation (base syringe only, left on top of cured adhesives in the dark for 20 minutes before activation). After micro-tensile bond strength evaluation, fractured samples were examined using SEM. Intact, unstressed interfaces of  and  were examined with TEM. Microtensile bond strengths were also evaluated for selected adhesives bonded to dehydrated dentin and coupled with the composite activated by  or . Results: For all adhesives, bond strengths decreased significantly to bonded hydrated dentin when the composites were activated with  or  (P< 0.001). Whereas the hybrid layer-adhesive interface was intact, water-blisters that developed along the adhesive-composite interface in these two modes were responsible for the decline in bond strength. When bonded to dehydrated dentin, delayed light-activation of the light-cured composite did not result in compromised bond strength. The results of chemical-cured composites improved but were more variable and system-dependent.
|Original language||English (US)|
|Number of pages||8|
|Journal||American journal of dentistry|
|State||Published - Aug 2004|
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