7'th International Congress on Adhesive Dentistry, Konya, Turkey, 1 - 03 June 2023, pp.38
Introduction: The aim of this study was to evaluate the effect of different surface treatments the repair bond strength of
a universal nanohybrid resin based composite (RBC) restorative material before- and after-dynamic aging, by utilising
micro-shear bond strength (MSBS) test.
Materials and Methods: For micro-shear bond strength test, total of 120 cylindrical (3mmX2mm) nanohybrid RBC
specimens were prepared (ClearfilMajesty ES-2, Kuraray/Japan). The prepared specimens were divided into three groups
(n=40/per group) based on surface treatment methods: a non-aged group (control group), 10,000cycle dynamic aging and
50,000cycle dynamic aging (thermocycle by 50°C and 55°C/Thermocycler The-1100, SD Mechatronik, Germany), which
corresponds 1-year and 5-year clinical thermal aging. The aged and non-aged specimens were further divided into four
groups: 1.aluminum oxide sandblasting+universal adhesive/self-etch mode, 2.aluminum oxide sandblasting+universal
adhesive/etch-and-rinse mode, 3.universal adhesive/self-etch mode, 4.universal adhesive/etch-and-rinse mode.
Subsequently, 0.8mmX2mm disc shape light cure RBC specimens were applied with direct placement technique
(ClearfilMajesty ES-2, Kuraray/Japan) on the treated surfaces of all samples for repair. All specimens were stored in
distilled water at 37°C in an incubator for 24-hour before micro-shear bond strength test. MSBS test was performed using
a universal testing machine (Schimadzu IG-IS, Japan) at a crosshead speed 1 mm/min until failure to obtain the maximum
load (P) in Newton (N). MSBS = P/CA where, P: load; CA: cross sectional area. The obtained Newton values were
converted to MPa values by calculating the surface area of the specimens. Data were analyzed statistically using two-way
analysis of variance (ANOVA) and Tukey at a confedence level 95% (p<0.05).
Results: Dynamic aging duration had a statistically significant effect on repair strength of MSBS (p<0.05). The highest
MSBS data were obtained from non aged/ aluminum oxide sandblasting+universal adhesive/etch-and-rinse mode test group
(p<0.05). Regarding aging test groups, the highest MSBS data were obtained from 10,000 and 50,000 thermal cycles with
group: universal adhesive/etch-and-rinse mode and aluminum oxide sandblasting+universal adhesive/self-etch mode,
Conclusion: As the dynamic aging duration increased, MSBS values decreased. Depending on the application mode of
universal adhesive, either self-etch mode or etch-and-rinse mode, further surface treatment by sandblasting other means
air-particle abrasion had beneficial effects on MSBS values.