# The influence of incorporation of hydroxyapatite/collagen nanocomposite into glass ionomer cement on surface roughness, microhardness, and fluoride-ion release potential

## TL;DR

This study examines how adding hydroxyapatite/collagen nanocomposite to glass ionomer cement affects its surface roughness, hardness, and fluoride release.

## Contribution

The study introduces a novel approach of incorporating HA/Col nanocomposite into GIC to enhance its mechanical and fluoride-releasing properties.

## Key findings

- Fluoride-ion release significantly increased in all experimental groups compared to the control.
- Surface microhardness improved in all experimental groups compared to the control.
- The 10% HA/Col (50:50) group showed significantly higher surface roughness than other groups.

## Abstract

To investigate the effect of incorporation of 5 and 10 weight% of hydroxyapatite /collagen (HA/Col) nanocomposite with different ratios (50:50) and (70:30) to conventional glass ionomer cement (C-GIC) on surface roughness, microhardness, and fluoride-ion release.

Seventy-five specimens were prepared using split Teflon mold (5 mm in diameter and 2 mm in thickness) and were randomly assigned to 5 different groups. Group I: control group of C-GIC, Group II: GIC modified with 5% HA/Col (50:50), Group III: GIC modified with 5% HA/Col (70:30), Group IV: GIC modified with 10% HA/Col (50:50), Group V: GIC modified with 10% HA/Col (70:30). The specimens were kept in deionized (DI) water and incubated at 37 °C.The DI water in each container was changed on the 1st, 7th, 14th, and 28th days. Fluoride ion release was assessed using the SPADNS colorimetric technique. Afterwards, a surface profilometer and a Vickers hardness tester were used to assess surface roughness and microhardness. Moreover, micromorphological analysis was assessed using SEM-EDX mapping.

Regarding fluoride-ion release, mixed linear model revealed significant increase of fluoride-ion release in the 4 experimental groups compared to control one (p < 0.0001). Regarding surface roughness, and microhardness, one-way ANOVA test revealed a significant increase of surface roughness of experimental group of 10% HA/Col (50:50) compared to rest of groups, and significant increase of surface microhardness of all experimental groups compared to control one.

Incorporation of HA/Col nanocomposite into C-GIC cement showed promising improvements in surface hardness and fluoride ion release.

The online version contains supplementary material available at 10.1186/s12903-025-07080-1.