Evaluation of Ion Release, Antibacterial characteristics, and Optical Properties of Newly Formulated Dental Composites with Zinc-Containing Glass Fillers

Abstract

Introduction: To create bacteriocidal zinc-releasing glasses for dental restorative applications, the decomposition of zinc-containing bioactive glasses has been previously researched. At neutral and higher pHs, relatively little zinc is released in bioactive glasses; only under acidic conditions is the zinc significantly released. Marginal leakage and recurrent decay are the main issues with modern restorative resin composites. Therefore, the creation of bioactive dental composites that include apatite-forming bioactive glasses is currently of great interest. Such composites would benefit from having a bacteriocidal characteristic, especially if the glass could release zinc under acidic conditions but not under neutral ones. Aims: The purpose of this study was to explore the feasibility of developing a novel dental composite containing zinc-releasing glasses that has radiopacity comparable to that of currently used resins in dental composites but does not produce apatite in both acidic and neutral environments. Methods: A melt quench method was used to synthesise three glasses with varying ZnO contents (0, 5, and 10%), which were then ground and sieved to create fine glass powders measuring 38 microns. The experimental dental composite discs had a 10 mm diameter, a 2 mm thickness, and an average weight of 0.35 grams. They were made using zinc-containing glass. 30% zinc-containing glass and 70% resin made up the mixture. Their characteristics were determined using XRD, ATR-FTIR, and dissolution tests in both Tris buffer at pH 7.35 and 0.1M acetic acid at pH 4. With the use of an ICP-OES and a fluoride ion selective electrode, ion release was monitored as a function of immersion time. Results: The Zn-containing glasses that were created (0, 5 and 10%) were amorphous. However, the generated Zn-containing glasses (5 and 10%) demonstrated a shift from an amorphous glass structure to the formation of crystalline apatite upon immersion in acetic acid and Tris buffer, as shown by XRD examination. But when submerged in acetic acid, all the ZnO-containing glasses quickly disintegrated. In contrast, the glasses disintegrated slowly and released relatively little Zn in the Tris buffer. Moreover, the radiolucency of the prepared Zn-containing composites was decreased with the increase of Zn percentage. Conclusions: When the concentration of ZnO was raised, apatite could be produced by Zn-containing bioactive glasses in both acidic and neutral conditions. Zn-containing bioactive glasses are probably more likely to dissolve fast at acidic pH values while slowly evaporating at neutral pH values. Due to ZnO integration, the experimental Zn-containing composite loses radiolucency as ZnO content increases.