Abstract

Mohammed A. Fadhil, Abdulla M. W. Al-Shamma

Aims (Purpose): The study aims were to prepare, characterize, and incorporate colloidal suspension containing Ascorbic Acid Coated Superparamagnetic Nanoparticles (AA-SPN) into two universal adhesives to increase the dentin Shear Bond Strength (SBS) and stability by subjecting them to external magnetic field. Settings and Design: An invitro study. Methods and Material: A colloidal suspension of AA-SPN was prepared, characterized, and incorporated into All Bond universal (Bisco, USA) and Prime&Bond universal (Dentsply, Sirona) at 2% by mass. Sixty-four freshly extracted third-molars were divided randomly into four groups, i.e., GI: All Bond Universal (control), GII: All Bond Universal (2%-incorporated), GIII: Prime&Bond universal (control), and GIV: Prime&Bond universal (2%-incorporated). GII and GIV are subjected to 1min magnetic force before adhesive curing. The teeth were restored with Filtek Z350 composite (3M ESPE, USA). Each group was subdivided into two subgroups of 8 teeth each. The first subgroup subjected to thermocycling followed by 1-day water storage, and the second subgroup subjected to thermocycling followed by 6- months water aging before testing the SBS. Statistical analysis used: Statistical analysis was conducted by independent variable t-test performed by using IBM-SPSS program version 22. Results: GII and GIV showed significantly higher (p<0.05) immediate SBS after thermocycling, and maintained a significantly higher bond strength after 6 months water aging in comparison to their control groups. GIV showed significantly higher SBS in comparison to the GII. Groups I, II showed the lowest SBS after 6 months of water aging. Conclusions: Universal adhesives containing 2% AA-SPN subjected to external magnetic field significantly improved the immediate and delayed shear bond strength values compared to their corresponding control adhesives. Significance: The synergistic actions of superparamagnetism of the magnetite nanoparticles in response to magnetic field, and the medicinal values of vitamin C including collagen cross linking and MMPs inhibition, significantly increased and maintained the bond strength of universal adhesive to sound dentin when subjected to external magnetic field in comparison to the non-incorporated adhesives