Effect of Er:YAG Laser and Reduced Time of Acid Etching on Bond Strength of Self-adhesive Resin Cement to MTA and Biodentine: Bond Strength of Pretreated MTA and Biodentine

Introduction: Considering the recent trend to use mineral trioxide aggregate (MTA) and Biodentine and resin cements, more conservative approaches concurrent with adequate bond strength have always been requested. The present study aimed to evaluate the effect of pretreatment with Er: YAG laser etching versus acid-etching for 5 and 15 seconds on the micro shear bond strength of selfadhesive resin cement (SRC) to MTA and Biodentine.Materials and Methods: Forty-eight samples of each cement (MTA and Biodentine) were prepared and distributed into four groups based on surface pretreatment: 1) control, no treatment; 2) Er: YAG laser etching with the energy of 60 mJ; 3) 5-second acid-etching; 4) 15-second acid-etching. All specimens were cemented using SRC. Microshear bond strengths were tested following 24-hour water storage. Debonded specimens were examined and surface topography was assessed using an atomic force machine (AFM). Data analysis was performed using the two-way ANOVA and Tukey multiple comparisons test.Results: The three testing groups of laser etch and 5-s and 15-s acid-etch demonstrated a significantly higher SBS than the control group (P<0.05) with negligible differences among them (P > 0.05). Furthermore, Biodentine showed better adhesive bonding than MTA in all groups.Conclusion: Laser etching of 60 mJ and 5-s acid-etching were as beneficial as 15-s acid-etching in terms of bond strength of SRC to MTA and Bodentine. Doi:10.34172/jlms.2021.3

Fracture Forces of Dentin after Surface Treatment with High Speed Drill Compared to Er:YAG and Er,Cr:YSGG Laser Irradiation

Dental tooth restorative procedures may weaken the structural integrity of the tooth, with the possibility of leading to fracture. In this study we present findings of coronal dentin strength after different techniques of surface modification. The fracture strength of dentin beams after superficial material removal with a fine diamond bur high speed drill hand piece, Er:YAG (2.94 μm, 8 J/cm2), and Er,Cr:YSGG (2.78 μm, 7.8 J/cm2) laser irradiation slightly above the ablation threshold was measured by a four-point bending apparatus. Untreated dentin beams served as a control. A total of 58 dentin beams were manufactured from sterilized human extracted molars using the coronal part of the available dentin. Mean values of fracture strength were calculated as 82.0±27.3 MPa for the control group (n=10), 104.5±26.3 MPa for high speed drill treatment (n=10), 96.1±28.1 MPa for Er,Cr:YSGG laser irradiation (n=20), and 89.1±36.3 MPa for Er:YAG laser irradiation (n=18). Independent Student’s t-tests showed no significant difference between each two groups (p>0.05). Within the parameter settings and the limits of the experimental setup used in this study, both lasers systems as well as the high speed drill do not significantly weaken coronal dentin after surface treatment