Effects of atmospheric-pressure-cold plasma application on micro-tensile bond-strength of universal adhesives on dentin

This study aimed to evaluate the short term (24 h) effects of atmospheric pressure-cold plasma application on the micro-tensile bond strength (µTBS) of universal adhesives to dentin.

Eighty-four extracted permanent molars were used, and three different universal adhesives [Scothbond Universal Adhesive, Clearfil Universal Bond Quick, All-Bond Universal] were tested. The teeth were randomly divided into 12 groups (n=7 teeth / 28beams) based on two main conditions: atmospheric-pressure-cold-plasma treatment [(APCP (+) or APCP (-)] and adhesive application mode [etch-and-rinse or self-etch]. Resin restorations were applied incrementally according to the study groups. The specimens were sectioned along the x and y axes using a precision diamond saw under water cooling to obtain specimens with 1mm² cross section. These specimens were fixed to a universal testing device and stressed until failure. The debonded specimens were examined under a stereomicroscope at ×40 magnification to determine the failure pattern. Data were analyzed using Welch's ANOVA followed by the Games-Howell post-hoc test. Failure mode data were analyzed using Chi-Square test (α = 0.05).

In the groups without plasma treatment, no statistically significant difference in bond strength was observed between etch-and-rinse and self-etch modes for any of the adhesives (p > 0.05). However, Clearfil Universal Bond Quick showed a statistically significant increase in bond strength after plasma treatment in both application modes (p < 0.05).

Within the limitations of this study, APCP demonstrated material- and application-mode-dependent effects on bond strength, indicating that its efficacy varies with adhesive composition and application strategy. APCP treatment showed no adverse effect on the bond strength of universal adhesives, suggesting its potential as an additional surface treatment step.