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Background: The aim of this study was to evaluate the shear bond strength (SBS) of two types of adhesives (total and self-etch) to dentin surface treated with 2% of chlorhexidine (CHX) conditioner. Materials and Methods: A total of 72 freshly extracted human sound premolar teeth were selected, washed and cleaned, and then divided randomly into three main groups; each tooth cusp was cut off until the first layer of dentin under the groove between the two cusps was exposed (superficial dentin). Then, 48 teeth were randomly selected to be used in Group I (control group) and Group II (n = 24 each). The remaining 24 teeth were selected to be used in Group III which were cut off until the deep dentine between the first layer of exposed dentin and pulp horn was exposed. Then, adhesives were applied on the exposed dentin in Group I without application of CHX intermediate. In Group II, 2% CHX was applied to the superficial dentin surface for 1 min and washed away before application of adhesives. In Group III, 2% CHX was applied to deep dentin surface for 1 min and washed away before applying adhesives. Instron machine was used to assess the SBS. Data were analyzed using one-way ANOVA and Tukey's post-hoc test. Results: The control group showed the higher mean SBS than the two groups as well as, bonding to superficial dentin in Group I and Group II showed higher mean bond strength when compared with deep dentin in both self-etch and total-etch groups. In general, selfetch showed higher bond strength than total etched adhesives. Conclusion: Bond strength of adhesives without using CHX was the highest compared with using CHX as dentine surface conditioner. However, self-etch was stronger than total etch, and also adhesives were weakest in deep than superficial dentin. [ABSTRACT FROM AUTHOR]

Background: The purpose of this study was to compare the shear bond strength of nanocomposite resin to superficial dentin and deep dentin using two different dentin bonding systems. Materials and Methods: All teeth were sectioned at various levels (superficial dentin: Dentin within 0.5-1 mm of dentinoenamel junction; deep dentin: Dentin within 0.5 mm of the highest pulp horn) using a Carborundum Disc and embedded in acrylic block of specific size. Selected specimens (60 premolar teeth) were grouped randomly into three groups, the groups were differentiated into superficial dentin, deep dentin, and control group which were further divided into sub Group A and Subgroup B containing 10 teeth each, depending on the bonding agents used. In Subgroup A, Tetric N Bond, and in Subgroup B Single Bond Universal were used. In the control group no bonding agent was used. The specimens were thermocycled for 500 cycles between 5°C and 55°C water bath for 40 s. Finally, the specimens were subjected to shear bond strength study under INSTRON machine (Universal Testing Machine). The maximum shear bond strengths were noted at the time of fracture (de-bonding) of the restorative material. Results were analyzed using ANOVA test, Bonferroni test, and paired t-test. Results: Bond strength values of fifth generation bonding system (Tetric N Bond) showed higher mean shear bond strength compared to seventh generation bonding system (Single Bond Universal). There was a significant fall in bond strength values as one reaches deeper levels of dentin from superficial to deep dentin. Conclusion: There was a significant difference between the bond strength of fifth generation bonding system (Tetric N Bond) and seventh generation bonding system (Single Bond Universal). Decrease in the bond strength values is seen for the deeper level of dentin as compared to superficial dentin. [ABSTRACT FROM AUTHOR]