الفهرس 
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Abstract
A total of 360 bovine mandibular permanent incisors were used for SBS testing. After extraction, the teeth were cleaned from blood and soft tissue and stored no longer than two weeks in 0.1% thymol solution at 4°C. Teeth were randomly divided into four main groups (90 specimens each) according to the adhesive used: a1 SBMP; a2: Excite; a3: AdheSE; a4: Adper Easy One. Each main group was divided into three groups (30 specimens each) according to the delay of composite placement: b0: No DP; b1: 1 min DP; b2: 3 min DP. Each group was further divided into three subgroups (10 specimens each) according to the curing of the adhesive resin: c0: No RC; c1: RC-Double; c2: RC-Triple.
The data for SBS testing was recorded in Newton and SBS values in MPa were calculated from the peak load at failure divided by the specimen surface area. Statistical analysis was carried out using SPSS program (SPSS, 2008). Three-way ANOVA was used to test the effect of adhesive material, delayed time, repeated curing and their interactions on the SBS (MPa). For each adhesive material, two-way ANOVA was used to test the effect of delayed placement, repeated curing and their interaction within each adhesive material on the SBS (MPa) as well as the effect of adhesive material, procedural variables (delayed placement and repeated curing) and their interaction on the SBS (MPa). One-way ANOVA was used to test the effect of adhesive materials, delayed time as well as repeated curing groups on bond strength within each other two factors. Duncan Post-Hoc Multiple Comparisons (Post-Hoc) at p≤0.05 was used for means comparison.
For the resin/dentin interface and nanoleakage evaluation, a total of 144 sound human permanent posterior teeth were used. Interfaces were observed using SEM at 1000x and 2000x magnification.
Within the limitations of this study, the following conclusions could be drawn:
1. Three-step etch-and-rinse adhesive SBMP is still the adhesive of choice regarding the immediate bond strength performance.
2. The 1-step self-etch adhesive tested in this study performed better than the 2-step self-etch adhesive, which is contrary to the available literature regarding these two adhesive categories.
3. The bond strength performance of the different adhesives tested was variable regarding the delay placement of composite and/or the repeated light curing.
4. Immediate placement of composite without delay as well as abiding by the curing time recommended by the manufacturer is necessary when AdheSE is used.
Recommendations:
Although studying both the resin/dentin interface and nanoleakage is very important in evaluating adhesive performance, it does not add any advantage when explaining differences in bond strength. It is obvious that bonding to dentin is a multi-factorial mechanism therefore, it is important to choose the proper evaluation test to either confirm or explain the results. As the in vitro study showed some limitations to proper evaluation, clinical evaluation is highly recommended.