الفهرس 
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Abstract
The aim of this study is to evaluate the microtensile bond strength (µTBS) of different multimode adhesives to dentin. Also to evaluate micromorphological and nanoleakage patterns of the resin-dentin interface. Methods: A total of thirty-six freshly extracted caries-free human permanent molars were divided into six groups according to type of adhesive and etching mode either etch-and-rinse (ER) or self-etch (SE). Bonded specimens were stored in deionized water for 24 hr (n=6). Composite/dentin beams were prepared (1 mm2). µTBS testing were performed. Four extra teeth from each group were prepared for micromorphological evaluation of resin-dentin interfaces using Scanning Electron Microscope (SEM) and nanoleakage evaluation was performed. µTBS data were statistically analyzed using two-way ANOVA and multiple comparison post hoc tests. Results : The two-way ANOVA revealed that the µTBS was significantly affected by the “type of adhesive material” (p<0.05) and “method of dentin surface treatment” (p<0.05). Tukey post hoc multiple comparison test showed that there was no significant difference in µTBS between acetone based adhesive (ER) (Scotchbond Universal) and acetone based adhesive (SE) (Scotchbond Universal) (p>0.05). However, there were significant difference in µTBS between water based adhesive (ER) (Adhese Universal) and water based adhesive (SE) (Adhese Universal) (p<0.05). Comparison among both materials showed that the µTBS of water based adhesive (ER) (Adhese Universal) was significantly higher than acetone based adhesive (ER) (Scotchbond Universal) (p>0.05). Hybrid layers created by these adhesives in the ER bonding mode and SE bonding mode were approximately ~5 mm and ≤0.5 mm thick respectively. Silver nitrate infused regions could be identified within the resin-dentin interface in all the bonded specimens. Conclusion: Application of an etching step prior to acetone based adhesive (Scotchbond Universal) improves its dentin penetration, but does not affect its µTBS while application of an etching step prior to water based adhesive (Adhese Universal) improves its dentin penetration and improves its µTBS. Clinical significance : The rationale behind this study was that a ‘multi-mode’ adhesive, when proved to be effective, would enable the general practitioner to apply the adhesive either following a ‘SE’ or ‘ER’ adhesive approach, basically depending on his/her interpretation of what appears most appropriate upon the actual cavity and overall restoration conditions.