# Comparative analysis of hydroxyapatite and zinc oxide nanoparticles for effective dentinal tubule occlusion in dentin hypersensitivity management: a profilometric and scanning electron microscopic investigation

## TL;DR

This study compares hydroxyapatite and zinc oxide nanoparticles for blocking tiny tubes in teeth to reduce sensitivity, finding zinc oxide more effective.

## Contribution

The study introduces a direct comparison of hydroxyapatite and zinc oxide nanoparticles for dentinal tubule occlusion in managing dentin hypersensitivity.

## Key findings

- Zinc oxide nanoparticles showed the most extensive dentinal tubule occlusion compared to hydroxyapatite nanoparticles.
- Zinc oxide nanoparticle-treated discs had the lowest surface roughness, indicating better effectiveness in dentin hypersensitivity management.

## Abstract

The objective of this study was to evaluate the efficacy of hydroxyapatite nanoparticles (HANPs) in comparison to zinc oxide nanoparticles (ZnO NPs) in occluding dentinal tubules (DTs). Managing dentin hypersensitivity (DH) and assessing the resilience of anti-hypersensitivity treatments present significant clinical challenges. Hence, it is imperative to explore the impact of NPs on DH treatment.

In this study, twenty- seven orthodontically extracted teeth with no caries or restorations were employed to produce 27 dentin discs. These discs were created by slicing the teeth coronally and subsequently subjecting them to a 20-second etching using 37% orthophosphoric acid to simulate DH conditions and eliminate the smear layer. The dentin discs were then randomly assigned to three groups: Group I (etched control), Group II (HANPs), where dentin discs were treated with carboxymethyl cellulose (CMC) dental hydrogel loaded with HANPs, and Group III (ZnO NPs), where dentin discs received treatment with CMC dental hydrogel loaded with ZnO NPs. Finally, the dentin discs underwent various analyses, including profilometric assessment to measure surface roughness (SRa) of dentin discs, qualitative assessment using scanning electron microscopy (SEM) to evaluate DT occlusion and quantitative assessment SEM images using Image J software platform.

Analysis of the dentin discs revealed that Group I had the highest SRa measuring 1.52 ± 0.08 μm, followed by Group II, measuring 1.21 ± 0.06 μm, while Group III exhibited the lowest SRa measuring 1.20 ± 0.05 μm. SEM examination indicated that Group III displayed the most extensive DT occlusion, followed by Group II, while Group I exhibited the lowest level of occlusion. The results from the SEM analysis were quantitatively validated through additional analysis using Image J software. Statistical analysis (ANOVA and post hoc Tukey’s test, p ≤ 0.05) revealed significant differences between groups, thereby rejecting the null hypothesis.

The application of ZnO NPs demonstrates a positive impact on both the qualitative and quantitative aspects of DH.

• The inclusion of ZnO NPs is anticipated to enhance clinical outcome in reducing dentin hypersensitivity by occluding dentinal tubules

• All authors agree with the submission

• The work has not been published or submitted for publication elsewhere, either completely or in part, or in another form or language

• No conflict of interest with the authors in this work