Comparative Evaluation of Microhardness, Water Sorption and Solubility of Biodentin and Nano-Zirconia-Modified Biodentin and FTIR Analysis

Aim: This study compares the microhardness, water sorption and solubility of nano-zirconia-reinforced biodentin groups to commercially available biodentine. Materials and Methods: Samples were prepared by adding different percentages of nano zirconia to biodentin. Four groups were categorized as follows: group 1 used Biodentin as the control group, group 2 used 10% nano zirconia and 90% Biodentine, group 3 used 20% nano zirconia and 80% Biodentine, and group 4 used 30% nano zirconia and 70% Biodentine. A Vickers microhardness tester was used to measure the microhardness of the groups according to ISO 4049/2000. The water sorption and solubility of the divided groups were assessed using disk-shaped molds. The second weight was measured on an electronic weight machine after two weeks, and values were recorded. FTIR analysis was performed. Vickers microhardness, water sorption and solubility were analyzed using a one-way ANOVA, and for multiple comparisons, a post hoc Tukey’s HSD test with a significance level of p < 0.05 was performed. Group 3 had the highest mean microhardness measurement among all groups. The microhardness values for all groups in descending order are as follows: group 3, group 2, group 1 and group 4 (p = 0.008). Group 2 showed the lowest mean of water sorption compared among all groups. Group 2 has the lowest mean of water sorption, followed by group 3, group 1 and group 4 (p = 0.002). Group 4 showed the highest water sorption among all groups. Group 4 exhibited the highest solubility mean among all groups. Group 1 had the lowest mean of solubility, followed by group 2, group 3 and group 4 (p = 0.000). The FTIR spectra of different types of biodentin showed the absorbance peaks of the precipitates of each modified biodentin. The absorbance peaks fell between 474.63 cm−1 and 3438.33 cm−1. Conclusion: Biodentin is a competitive biomimetic material, but it lacks hardness and has more solubility. Thus, adding nano zirconia improved microhardness and reduced water sorption. The solubility of 20% nano zirconia added to biodentin was almost close to biodentin but with no significance. The 20% nano-zirconia-modified biodentin showed overall better properties compared to biodentin. The 20% nano-zirconia-modified biodentin can be used in deep cavities as a single restorative material instead of multi-layered restorations to increase longevity without microleakage and failure of restoration.