Enhancing the durability and antibacterial activity of glass ionomer restorative material enriched by l-arginine and nano-titanium for pit and fissure sealing

Abstract

Abstract Background Sealing teeth’ pits and fissures is of prime importance in preventing caries. Despite the evidenced bioactivity of glass-ionomer cements (GICs), they still fail to totally inhibit caries. This partially might be due to their insufficient antibacterial and strength properties. l-arginine (Arg) has superior caries-preventive potential thanks to its prebiotic-based biofilm-modulating effect. Titanium dioxide (TiO2) on the other hand, has well-known antibacterial characteristics, and being in nano size is supposed to improve strength. Therefore, this study aims to improve the antibacterial efficiency and the mechanical properties of conventional GICs using 1% Arg and 3% TiO2 nanoparticles for pit and fissure sealing. Methods Etched enamel surfaces of 100 extracted human third molars were randomly divided into two groups; a control group, where teeth were restored using glass ionomer Ionofil Plus, and an experiment group, where teeth were restored using glass ionomer Ionofil Plus incorporating Arg–TiO2. Specimens of both groups were tested for microleakage, enamel shear bond strength, and fluoride ion release using a stereo microscope, universal testing machine, and ion chromatography ICs 5000+ SP respectively. Surface analysis was conducted through scanning electron microscopy coupled with energy-dispersive X-ray analysis (SEM–EDX) and atomic force microscope (AFM). Furthermore, specimens of both groups were incubated with Streptococcus mutans, Lacticaseibacillus rhamnosus, and Actinomyces viscous for quantitative antibacterial evaluation, compared to a specimen-free control using adherent/planktonic bacterial count test. Results The experimental group had statistically lower microleakage percentage, higher shear bond strength, and constant fluoride release compared to the control group at P = 0.01, 0.002, and < 0.001 respectively. SEM of the experimental group revealed hybrid particles of the Arg–TiO2 incorporating GIC with clusters of uniformly distributed TiO2 nanoparticles. AFM showed lower surface roughness for the experimental group indicating its homogeneity. The adherent probiotic L. rhamnosus bacterial count had the highest count in Arg–TiO2 (IP) GIC group (P < 0.001) with lack of adherent pathogenic S. mutans bacterial count compared to planktonic/adherent S. mutans bacterial count in the control group and (IP) GIC group (P < 0.05). Conclusions Incorporating 3% TiO2 nanoparticles and 1% Arg in GICs can enhance their mechanical properties, fluoride release, and antimicrobial efficiency.