Objectives and scope: The aim of this invitro study was to evaluate and compare the effect of smear layer removal modification on push out bond strength of MTA, Biodentine and Cem cement as a dental biomaterial. This modification was done by comparing two methods using chemical surface treatment and double-wavelength laser irradiation in endodontics. Method: One hundred ten human anterior extracted teeth were decoronated, cleaned and shaped to the same size apically and randomly divided into 3 major groups: (1) smear layer preserved, (2) smear layer removed using irrigation with 17% EDTA, and (3) smear layer was removed by double-wavelength (940 nm + 2780 nm) lasers. Three slices of 1±0.1mm in thickness was obtained from each root, so divided into 3 subgroups according to the obturation material used: (A) ProRoot MTA, (B) Cem cement, (C) Biodentine. The specimens were stored in synthetic tissue fluid for 7 days to allow maximum setting of the root filling materials. Push-out bond strength test was carried out using a universal testing machine. The bond failure mode was assessed under an optical microscope at 40×. Results: The mean push-out bond strength in subgroups 1A, 2A and 3A were 5.25± 2.13, 5.36±2.55 and 5.31±2.73 MPa respectively, while those for subgroups 1B, 2B and 3B were 3.35±1.82, 6.33±2.72 and 5.63±3.66 MPa, and for subgroups 1C, 2C and 3C were 5.34±2.70, 5.42±3.04 and 5.42±2.48, respectively. The push-out strength value was significantly reduced when the smear layer was preserved in the Cem cement groups (P < 0.05) while no significant difference was detected in the other groups. Conclusions. Based on the conditions of this ex vivo study, it can be concluded that smear layer removal is detrimental to the bond strength between Cem cements and dentin.
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