Objective: The aim of the study was to evaluate shear bond strength (SBS) and modes of failure for bioactive (BA) material when bonded to Er,Cr:YSGG lased dentin in comparison with other conditioning regimes. Materials and methods: One hundred twenty extracted teeth were mounted and allocated into eight groups ( n = 15) according to the surface conditioning [group 1: Er,Cr:YSGG laser + BA; group 2: Er,Cr:YSGG laser + multi-core (MC); group 3: Er,Cr:YSGG + Ketac Conditioner (polyacrylic acid) + BA; group 4: Er,Cr:YSGG + Ketac Conditioner + MC; group 5: conventional etch and rinse + BA (Control); group 6: conventional etch and rinse + MC (Control); group 7: self-etch + BA; group 8: self-etch + MC]. Based on the type of bulk-fill material, samples from groups 1, 3, 5, and 7 were bonded to BA and groups 2, 4, 6, and 8 were bonded to conventional MC bulk-fill material. All specimens were tested for SBS using universal testing machine. Ten samples from each group were assessed for modes of failure. Data were assessed using analysis of variance and Tukey multiple comparisons test. Results: The maximum SBS value was in group 6 (18.96 ± 0.315) with etch and rinse dentin conditioning and bonded to MC. The minimum SBS value was exhibited by group 7 (16.04 ± 0.854) self-etch conditioning bonded to BA. SBS among group 6 specimens were significantly higher than that of specimens in group 7 ( p < 0.05). Among all groups the most common type of observed failure was adhesive. Conclusions: Dentin surface treatment with Er,Cr:YSGG phototherapy for the adhesive bonding of BA and conventional bulk-fill resin composite MC showed comparable bond strength outcomes to conventional conditioning techniques. Er,Cr:YSGG laser dentin conditioning of dentin for bonding of bulk-fill BA materials has potential to be used clinically as it shows potential for adequate adhesive bond integrity.

The study aimed to analyze the effect of the addition of nano-hydroxyapatite (nano-HA) particles on the mechanical properties of experimental adhesive (EA). Furthermore, dentin interaction of EA (without nano-HA) and EA with nano-HA (hereon referred to as HA-10%) were also investigated and equated. Methods consisting of scanning electron microscopy (SEM)–energy-dispersive X-ray spectroscopy (EDX), micro-Raman spectroscopy, micro-tensile bond strength (µTBS) test, and Fourier transform infrared (FTIR) spectroscopy were employed to study nano-HA particles shape, dentin bond strength, degree of conversion (DC), and adhesive–dentin interaction. Ninety teeth (N = 90) were collected, and pre-bonding, conditioning of dentin was performed utilizing phosphoric acid (H₃PO₄) etching, photodynamic therapy (PDT), and ER-CR-YSGG (ECY) laser. The teeth were set to form bonded specimens using two adhesives. Nano-HA particles were spherical-shaped, and EDX confirmed the presence of oxygen, calcium, and phosphorus. Micro-Raman spectroscopy revealed distinct phosphate and carbonate peaks for nano-HA. The µTBS test demonstrated highest values for HA-10% group on the H₃PO₄ conditioned dentin. The greatest DC was observed for the EA group. The addition of nano-HA-10 wt.% particles in dentin adhesive resulted in improved bond strength. The incorporation also demonstrated acceptable DC (although lower than EA group), suitable dentin interaction, and resin tag formation.