Effect of adding sodium fluoride and nano-hydroxyapatite nanoparticles to the universal adhesive on bond strength and microleakage on caries-affected primary molars

Evaluation of micro tensile bond strength (μTBS) and marginal leakage of sodium fluoride (NaF) and nano-hydroxyapatite (n-HA) modified universal adhesives (UAs) bonded using etch-and-rinse (ER) and self-etch (SE) bonding technique to the carious affected dentin (CAD). One hundred and twenty primary molars were prepared for CAD on the occlusal surface. The occlusal CAD surface was flattened and underwent a polishing procedure. The specimens were divided into six groups using a random allocation method based on the UAs applied and the mode of etching used (n = 20) Group A1: UAs (ER), Group B1: UAs (SE), Group A2: UAs (NaF) + ER, Group B2: UAs (NaF) + SE, Group A3: UA (n-HA) + ER and Group B3: UAs (n-HA) + SE. Composite restoration was placed and samples were thermocycled. Microleakage, μTBS, and failure mode assessment were performed using a dye penetration test, universal testing equipment, and stereomicroscope respectively. The μTBS and microleakage results (mean ± SD) were examined using analysis of the variance (ANOVA) and Tukey tests. Group B1 (UAs + SE) demonstrated the maximum scores of microleakage (25.14 ± 9.12 nm) and minimum recorded value of μTBS (14.16 ± 0.55 MPa). In contrast, Group A3 (UAs (n-HA) + ER) displayed a minimum value of marginal leakage (12.32 ± 6.33 nm) and maximum μTBS scores (19.22 ± 0.92 MPa). The outcomes of the intergroup comparison analysis showed that Group A2 (UAs (NaF) + ER), Group B2 (UAs (NaF) + SE), Group A3 (UA (n-HA) + ER) and Group B3 (UAs (n-HA) + SE) presented comparable outcomes of marginal seal outcomes and μTBS scores ( > 0.05). NaF and n-HA-modified UAs displayed favorable bond strength and minimum marginal leakage to the deciduous affected dentin surface.