Effects of Er,Cr:YSGG Laser Disinfection on the Bond Strength of Bioactive-Restorative Materials to Caries-Affected Dentin

<b><i>Objective:</i></b> This study aimed to evaluate the effects of different Er,Cr:YSGG laser disinfection protocols on the bonding performance of bioactive restorative materials to caries-affected dentin (CAD). <b><i>Background:</i></b> With the adoption of minimally invasive caries removal techniques, bonding to CAD has become increasingly important. Adhesion challenges caused by CAD can be overcome through the application of effective disinfection methods and the selection of compatible bioactive restorative materials. <b><i>Methods:</i></b> A total of 120 human third molars (240 specimens) were prepared, with dentin surfaces exposed under water cooling. After pH-cycling to simulate CAD, specimens were assigned to four disinfection groups: no disinfection (C), 2% chlorhexidine gluconate (CHX), Er,Cr:YSGG laser at 0.5 W (L1), and 1 W (L2). Four restorative materials (<i>n</i> = 12 per group)-G-ænial Achord (a resin composite used as the control group), Equia Forte HT, Beautifil-II Restorative, and Cention Forte-were applied according to manufacturers' instructions. Shear bond strength (SBS) testing was conducted on 192 specimens, while energy-dispersive spectroscopy (EDS) analyzed F, P, and Ca on 48 specimens, and scanning electron microscopy images were obtained from representative specimens. <b><i>Results:</i></b> CHX disinfection significantly improved SBS compared to the control group. Among restorative materials, G-ænial Achord showed the highest SBS, while Equia Forte HT demonstrated the lowest (<i>p</i> < 0.05). L1 disinfection combined with G-ænial Achord achieved the highest bond strength, whereas its combination with Equia Forte HT resulted in the lowest (<i>p</i> < 0.05). EDS revealed increased fluoride content on CAD surfaces treated with CHX. <b><i>Conclusion:</i></b> Er,Cr:YSGG laser disinfection at 0.5W improved bonding performance for resin composites. Selecting a disinfection protocol based on the restorative material is crucial for optimizing adhesion to CAD.