title: Evaluation of Shear Bond Strength of Newer Bonding Systems on Superficial and Deep Dentin.
abstract: 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.
  
  
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Professor and Head, Department of Conservative Dentistry and Endodontics, MR Ambedkar Dental College and Hospital, Bengaluru, Karnataka, India.
authors.forename: R Veena
authors.initials: RV
authors.lastname: Kumari
authors.affiliation: Postgraduate Student, Department of Department of Conservative Dentistry & Endodontics, MR Ambedkar Dental College & Hospital, Bengaluru, Karnataka, India.
authors.forename: Kishore
authors.initials: K
authors.lastname: Siddaraju
authors.affiliation: Postgraduate Student, Department of Conservative Dentistry & Endodontics, MR Ambedkar Dental College & Hospital, Bengaluru, Karnataka, India.
authors.forename: Hema
authors.initials: H
authors.lastname: Nagaraj
authors.affiliation: Postgraduate Student, Department of Conservative Dentistry & Endodontics, MR Ambedkar Dental College & Hospital, Bengaluru, Karnataka, India.
authors.forename: Ramya Krishna
authors.initials: RK
authors.lastname: Poluri
keywords: Bonding; deep dentin; self-etch; superficial dentin; total-etch