A novel application of nano eggshell/titanium dioxide composite on occluding dentine tubules: an in vitro study

Abstract To synthesize Nano eggshell-titanium-dioxide (EB@TiO2) biocomposite and to evaluate its effectiveness in occluding opened dentine tubules. EB@TiO2 was synthesized and characterized using X-ray diffraction (XRD), and Transmission Electron Microscope (TEM). Sixteen simulated bovine dentine discs were prepared and randomly assigned into four groups according to the following treatment (n = 4): Group 1: No treatment; Group 2: eggshell powder; Group 3: EB@TiO2; Group 4: Sensodyne. These were then agitated in a solution of 1g powder and 40mL water for 3hours. Thereafter, each dentine discs from the respective groups were post-treated for 5 min with 2wt% citric acid to test their acid resistant characteristics. Scanning Electron Microscope (SEM) was used to observe the effectiveness of occluded dentine pre-and post-treatment. The cytotoxicity of the synthesized EB@TiO2 was tested using NIH 3T3 assay. ANOVA was used to evaluate the mean values of the occluded area ratio and the data of MTS assay. This was followed by a multi-comparison test with Bonferroni correction (α = .05). The XRD confirmed that EB@TiO2 was successfully modified through ball-milling. The TEM revealed the presence of both spherical and irregular particle shape powders. The SEM result showed that EB@TiO2 could effectively occlude open dentine tubules. Equally, the result demonstrated that EB@TiO2 exhibited the highest acid resistant stability post-treatment. NIH 3T3 assay identified that EB@TiO2 had little effect on the NIH 3T3 cell line even at the highest concentration of 100µg/ml. This study suggests that the application of EB@TiO2 effectively occluded dentine tubules and the occlusion showed a high acid resistant stability.

Solubility of nanofilled versus conventional composites

Solubility of resin-based composite materials is of great importance in restorative dentistry, since inorganic ions present as fillers within composites can leach into the surrounding environment resulting in breakdown of the restoration. The aim of this study was to evaluate and compare solubility values of three different nanofilled light-activated composites with other four conventional composite dental materials. Seven commercial light-activated composite materials: Tetric Evo Ceram, Premise, Herculite, Z100, Z250, P60, Supreme XT. Ten disc specimens were prepared for each composite material using a stainless steel mold with 15 mm in inner diameter and 1 mm in thickness. The curing of each composite specimen was divided into five segments and each segment was photo-cures for 40 seconds. Water solubility of different materials was calculated by means of weighting the samples before and after water immersion [15 days] and desiccation. Data were analyzed by one-way ANOVA at 5% level of significance. Tetric Evo Ceram composite showed the lowest solubility values, while Premise composite dis-played the highest values. Solubility values of the tested composites did not show significant differences among them [P>0.05]. All the composites being tested in this study exhibited solubility values within the acceptable limits and composite composition is insignificantly influences its water solubility values