# Comprehensive Toxicological Evaluation of 3D-Printed Hydroxyapatite (3DPHA) for Bone Grafting Applications

## TL;DR

This study confirms that 3D-printed hydroxyapatite is chemically pure and biologically safe for use in bone grafting.

## Contribution

The paper provides the first comprehensive toxicological and compositional validation of 3DPHA for clinical use.

## Key findings

- 3DPHA showed phase-pure hydroxyapatite with a non-stoichiometric Ca/P ratio and low trace impurities.
- In vitro tests found no cytotoxic, irritant, sensitizing, or mutagenic effects of 3DPHA.
- The material complies with international benchmarks and is ready for clinical translation.

## Abstract

Binder jet 3D printing combined with a low-temperature phase transformation process has emerged as a promising route for producing 3D-printed hydroxyapatite (3DPHA) scaffolds with controlled architecture for bone grafting applications. However, the toxicological profile of this unique binder jet-derived material has not yet been established. In this study, we conducted a comprehensive compositional and toxicological assessment of 3DPHA fabricated via the calcium sulfate transformation route. The material exhibited phase-pure hydroxyapatite (HA) with a Ca/P ratio consistent with non-stoichiometric HA and low levels of trace elemental impurities. In vitro assays revealed no cytotoxic, irritant, sensitizing, or mutagenic effects. This work provides a standardized toxicological and compositional safety validation of 3DPHA. By linking compositional purity to biological safety and demonstrating compliance with international benchmarks, this study establishes a regulatory foundation confirming that 3DPHA is chemically pure, biologically safe, and ready for clinical translation as a bone-graft material.