Sodium fluoride addition to a two-step etch-and-rinse adhesive system: effect on dentin microtensile bond strength and durability

Studies have suggested that sodium fluoride (NaF) has an inhibitory effect on the activity of endogenous matrix metalloproteinase enzymes. This study assessed the effect of a fluoride-containing adhesive on microtensile bond strength (µTBS) over time.
Material & In this experimental study, 36 extracted third molars were used to evaluate the µTBS of a 5th generation adhesive modified by NaF. The exposed dentin surfaces were abraded and built up using composite resin. Then, the specimens were randomly divided into three groups of 12 teeth based on the type of adhesive used: Solobond M with no inhibitor (control); Solobond M with 5,000 ppm NaF; and Solobond M with 10,000 ppm NaF. The µTBS and failure mode of specimens were evaluated after 24-hour and 3-month storage in distilled water. Data were analyzed using ANOVA and Tukey’s test. P<0.05 was considered as significant level. The control group demonstrated a lower µTBS than the experimental groups after 24 hours and 3 months (p<0.05). The µTBS was higher in adhesive with 5,000 ppm NaF than in control group after 3 months (p<0.05). The group with 10,000 ppm NaF had the highest µTBS after 24 hours and 3 months (p<0.05). The fluoride-containing adhesives showed significantly higher bond strength values than the original adhesive without fluoride after 24-hour and 3-month storage in distilled water, leading to the improvement of resin-dentin bonds