Evaluation of Dentin Remineralization with Zinc Oxide and Calcium Fluoride Nanoparticles - An In vitro Study.

Abstract

Background: Partially demineralized dentin is remineralizable when mineral ions are made available in the near vicinity. Nanoparticles (NPs) have wide applications in remineralization process. Zinc promotes remineralization and has a synergistic effect when combined with fluoride. Hence, zinc oxide and calcium fluoride NPs were considered for dentin remineralization.

Aim: The aim of this study was to evaluate the remineralizing ability of zinc oxide and calcium fluoride NPs on demineralized dentin individually and in combined form.

Settings and design: This was an in vitro study.

Materials and methods: Forty-eight dentin disks were prepared from the crowns of 12 extracted human molars and were allocated into four groups of 12 each, i.e., Group I - nano zinc oxide (nZnO), Group II - nano calcium fluoride (nCaF₂), Group III - combined group (nZnO + nCaF₂), and Group IV - artificial saliva (AS, control group). The specimens were demineralized with 37% phosphoric acid and placed in the respective remineralizing solutions for 24 h and 1 month. Calcium (Ca) and phosphorous (P) uptake was measured using energy-dispersive X-ray spectrometry, and structural changes were analyzed using scanning electron microscopy (SEM).

Statistical analysis: One-way analysis of variance, Student's t-test, and post hoc Tukey's test were used for statistical analysis.

Results: At 1-month interval, all the groups showed an increase in Ca/P ratio, with highest being the combined group (4.24), followed by nCaF₂ (3.30), nZnO (1.71), and AS (1.31) groups, and these differences were statistically significant (P = 0.000). On SEM analysis of dentinal samples at 1 month, depositions were evident in intertubular regions, wherein the highest deposits were observed in the nZnO group, followed by nZnO + nCaF₂ and nCaF₂ groups.

Conclusion: Dentin samples subjected to remineralization with aqueous solutions of nZnO and nCaF₂ showed an increase in calcium and phosphorous uptake and also dense granular depositions were evident in intertubular regions of dentin.