Background and Aim: Intracanal medicaments can affect the bond strength of composite to dentine. The aim of this study was to evaluate the effect of 2o/o chlorhexidine [CHX] gel as an intracanal medicament on shear bond strength of three different composite resins to dentin. Materials and Methods: In this in-vitro study, 60 intact extracted human premolars were utilized. Each tooth was sectioned vertically and dentin of the buccal surface was exposed. Then, specimens were divided into six groups of l0 teeth. In groups l-3, dentin was exposed to CIIX and in groups 4-6, dentin was exposed to saline. All prepared surfaces were rinsed with distilled water and dentin bonding agent specific for each composite was applied on the dentin surfaces.2100, 2350 and P90 composites were applied to the treated swfaces and cured. The shear bond strength was recorded in Newtons and converted to MPa. Data were analyzed using the Kruskal-Wallis and Mann- Whitney U tests.
Results: The lowest mean shear bond strength was reported for normal saline and 2100 composite group [18.47 MPa] and the highest for CHX and 2350 grotry [42.26 MPa] . No statistically significant difference in bond strength values was found between normal saline and CHX groups [p>0.05] . There was a significant difference in bond strength values of different composite resins in normal saline [p<0.05] and also in CIIX groups b<0.05] .