Objectives: This study focuses on the properties of nanohydroxyapatite (nHAp) in terms of remineralization and acid resistance. The nHAp were produced from waste eggshells via the mechanochemistry process. Materials and methods: The characterization was based on Fourier Transform Spectroscopy, X-ray diffraction, Field Scanning Electron Microscope (FESEM), and High-Resolution Electron Microscope to determine the surface morphology of the nHAp. The acid and remineralization properties were evaluated using bovine enamel and dentine models ( n = 5) while the buffering properties against acids were studied using a pH meter. The biocompatibility of the produce nHAp was assessed in vitro against NIH 3T3. Results: The XRD and FTIR results confirm that nHAp were successfully produced from eggshell waste after 5 h of milling. The HRTEM reveals a semi-sphere morphology with an average dimension of 9 to 20 nm. The buffering test suggests that nHAp were highly effective in neutralizing common dietary acids. Also, the nHAp exhibits outstanding remineralization and occluding properties. The cytotoxicity assay suggests that the nHAp had a low toxicity. Conclusion: The study concludes that using eggshell waste to produce nHAp will help in waste management and at the same time, provide valuable biomaterial for the treatment of tooth sensitivity.

This paper reports on the in vitro assessment of the acid resistance characteristics of mesoporous silica/nanohydroxyapatite (MSN@nHAp) biocomposite synthesized through the mechanochemical method. Bovine enamel models were used to study the acid resistance characteristics of the composite ( n = 5 ). X-ray diffraction and Fourier transform infrared spectroscopy were used to characterize the surface morphology of the MSN@nHAp. The XRD and FTIR results confirmed the successful syntheses and surface modification of nanohydroxyapatite with silica. The MSN@nHAp exhibits superior acid resistance characteristics. The salient aspect of this study suggests that mechanochemistry is a useful technique in the synthesis and surface modification of valuable biomaterials. The study concludes that the MSN@nHAp composite could be utilised in toothpaste formulation for oral healthcare management due to its acid resistance properties.

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