Title: 3393 - Physicochemical Properties of Hydroxyapatite-Microclusters Used in Oral Care


Joachim Enax (Presenter)
Dr. Kurt Wolff GmbH & Co. KG

Helge-Otto Fabritius, Max-Planck-Institut für Eisenforschung GmbH
Kathia Fabritius-Vilpoux, Max-Planck-Institut für Eisenforschung GmbH
Frederic Meyer, Dr. Kurt Wolff GmbH & Co. KG
Matthias Epple, University of Duisburg-Essen


Objectives: Particulate hydroxyapatite, Ca5(PO4)3(OH), is used as a biomimetic oral care agent for toothpastes and mouthwashes. The efficacy of this agent, e.g. in occlusion of open dentin tubuli, depends on its physicochemical properties. The aim of this study was therefore to analyze composition, microstructure, and the particle size distribution of different hydroxyapatite powders intended for use in oral care products.

Methods: Commercially available hydroxyapatite powders were thoroughly characterized by various analytical methods, including X-ray powder diffraction (analysis of the mineral phase), atomic absorption spectroscopy (quantitative chemical analysis), energy dispersive X-ray spectroscopy (qualitative chemical analysis), scanning electron microscopy (microstructural analysis), and laser diffraction (analysis of the particle size distribution). A human molar was characterized as a reference.

Results: X-ray powder diffraction and chemical analyses confirmed that the phase of the powders is a pure hydroxyapatite without any other phase. Scanning electron microscopy images showed only strongly aggregated particles. Free individual primary particles were not observed. Laser diffraction analysis showed that all powders have an average cluster size of several micrometers, even after an intense ultrasonic pretreatment. The physicochemical properties of the analyzed hydroxyapatite powders are very similar to human enamel crystallites.

Conclusions: The analyzed hydroxyapatite powders are ideally suited as biomimetic oral care agents (e.g. for the occlusion of open dentin tubuli) due to their cluster morphology in the micrometer-range as well as due to the high chemical and structural similarity to natural enamel crystallites.

Disclosure Statement:
The submitter must disclose the names of the organizations with which any author have a relationship, the nature of the relationship, and the clinical or research area involved. The following is submitted: NONE