Fabrication of TiO2 Nanoparticles by Microbial, Green and HydrothermalMethodsandtheirPossible Role inDeveloping Novel Restorative Material for Dental Caries

Abstract

Globally, dental caries has been increasing with the passage of time despite the recent technological advancements in the field of dentistry. Nanotechnology has created new opportunities for the development of innovative materials with desirable strength, longevity and better efficacy. The current study was designed to produce and characterize the titanium oxide nanoparticles (TiO2-Nps) using biological and hydrothermal methods. Furthermore, the prepared TiO2Nps were evaluated for their antimicrobial activity and suitability in developing innovative glass ionomer cement (TiO2GIC) for dental caries treatment. During first phase, TiO2-Nps were synthesized via three routes including Bacillus coagulans, Mentha spicata and Conventional hydrothermal heating. The synthesis of Nps was carried out under different process temperatures based on material‘s sensitivity. The change in yellow color of Bacillus coagulans culture solution, green color of Mentha spicata leaf extract and black color of titanium tetrachloride solution in the flasks to white color confirmed the formation of TiO2-Nps. In the second phase, these TiO2-Nps were characterized for their size, shape, phase form, surface roughness, morphology, topography, elemental composition, band gap energy and functional groups by utilizing standard techniques such as X-ray diffraction analysis (XRD), Scanning electron microscopic analysis (SEM), Atomic force microscopic analysis (AFM), UV/Vis diffuse reflectance spectroscopic analysis (DRS), Energy dispersive x-ray spectroscopic analysis (EDS), Fourier transform infrared spectroscopic analysis (FTIR), Dynamic light spectroscopic analysis (DLS) and Raman spectroscopic analysis (Raman). The TiO2-Nps synthesized by Bacillus coagulans were found to have spherical shape with diameter of 21.84 nm size and showed 100% pure anatase phase with no impurity. The TiO2-Nps prepared by Mentha spicata depicted slightly irregular spherical shaped particles having a size of about 37.60 nm in diameter and showed100% pure anatase phase form with no impurity in elemental composition however, carbon dixide was detected as a trace impurity. On the other hand,TiO2-Nps fabricated by Conventional hydrothermal heating manifested particle size of about 52.28nm in diameter, 82% anatase and 18% rutile phase without any impurity in its elemental composition. Thenitro-compounds and carbon dioxide was observed in their functional groups as trace impurities. The third phase antimicrobial activity of TiO2-Nps synthesized by all the three routes against Escherichia coli (ATCC®35218TM), Lactobacillus acidophilus (ATCC®314TM), Enterococcus faecalis (ATCC®29212TM), Enterococcus faecium (ATCC®51559TM), Staphylococcus aureus (ATCC®25923TM) and Pseudomonas aeruginosa (ATCC®27853TM) was determined with the help of agar disc diffusion test. The antimicrobial activity of Bacillus coagulans TiO2-Nps against E. coli (27 mm + 0.70), L .acidophilus (26 mm + 0.70), E. faecalis (26 mm + 0.70), (ATCC®51559TM) (13 mm + 1.58), S. aureus (21 mm + 1.58) and P. aeruginosa (25 mm + 0.70) was comparatively higher from the TiO2-Nps prepared by Mentha spicata and Conventional hydrothermal heating (P-value< 0.05). The fourth phase investigated the biocompatibility of TiO2-Nps synthesized by all the three routes via MTT assay. The Bacillus coagulans drived TiO2-Nps depicted highest level of biocompatibility against fibroblast cell lines at all of the serial dilutions (99.57%, 97.43%, 95.51% and 93.00%) in comparison to TiO2-Nps prepared by Mentha spicata i.e. (99.35%, 95.82,92.09% and 90.79%). In case of TiO2-Nps fabricated by Conventional hydrothermal heating displayed least biocompatibilty of 98.92%, 94.43%, 9188% and 87.15%, and found to be mildly cytotoxic (P-value < 0.05). The 2 fifth phase incorporated the most suitable and biocompatible TiO2-Nps in the dental restorative material named glass ionomer cement in order to test its mechanical properties. The Bacillus coagulans TiO2-Nps were comparatively biosafe, biocompatible and acceptable to be incorporated in conventional dental glass ionomer cement (GIC) in the percentages of 0%, 3%, 5%, 7% and 10% in order to generate an innovative TiO2GIC dental restorative material. The different percentages of TiO2GIC dental restorative material was tested for its mechanical strength properties such as micro-hardness, compressive strength, flexural strength, shear bond strength, and surface morphology. The current study concluded that microbial synthesis was much better choice for making nanoparticles with better strength and antimicrobial properties. The 5% TiO2GIC dental restorative material was not only found to be biosafe and biocompatible but possessed the maximum mechanical strength properties such as micro-hardness, compressive strength, flexural strength, shear bond strength (P-value < 0.05). Moreover, 5% TiO2GIC dental restorative material revealed the minimum crack formation and porosity. The magnified strength displayed by this innovative restorative material would be capable of bearing the excessive masticatory stresses in the oral cavity without undergoing any distortion in order to escalate its longevity, extra-stability and ideal shelf life. Therefore, the incorporation of TiO2NPs proved to be better candidate for developing the long lasting dental restorative materials to treat the dental caries and could be used for commercial preparations conveniently and more feasibly in the current era. Key Words: Bacillus coagulans, Dental Caries, Glass Ionomer Cement (GIC), Restoration, Titania Nanoparticles (TiO2-Nps).