CC BY 4.0 · Eur J Dent 2020; 14(03): 335-341
DOI: 10.1055/s-0040-1714759
Original Article

In Vitro Whitening Effect of a Hydroxyapatite-Based Oral Care Gel

Sandra Sarembe
1   Fraunhofer Institute for Microstructure of Materials and Systems IMWS, Halle, Germany
Joachim Enax
2   Research Department, Dr. Kurt Wolff GmbH and Co. KG, Bielefeld, Germany
Maria Morawietz
1   Fraunhofer Institute for Microstructure of Materials and Systems IMWS, Halle, Germany
Andreas Kiesow
1   Fraunhofer Institute for Microstructure of Materials and Systems IMWS, Halle, Germany
Frederic Meyer
2   Research Department, Dr. Kurt Wolff GmbH and Co. KG, Bielefeld, Germany
› Author Affiliations
Funding This study was funded by Dr. Kurt Wolff GmbH & Co. KG, Bielefeld, Germany.


Objective Oral care formulations aim to prevent oral diseases such as dental caries and gingivitis. Additionally, desire for white teeth still exists across all age groups. It is known that most whitening toothpastes are highly abrasive and can be harmful to teeth and gingiva. Therefore, a gel formulation with biomimetic hydroxyapatite (HAP; Ca5[PO4]3[OH]) as active ingredient was developed. This formulation was tested with respect to its tooth whitening properties in an in vitro study.

Materials and Methods Enamel samples were allocated to either group (a) HAP gel, (b) whitening mouth rinse with phosphates, or (c) negative control (distilled water). Test products were applied by finger (a) or were rinsed (b, c) for 1, 3, and 9 (b and c only) cycles, respectively.

Results Color changes (ΔE) were measured spectrophotometrically. Group (a) showed a significant increase in color changes with respect to whitening after one cycle (mean ΔE = 5.4 [±2.66], p ≤ 0.006) and three cycles (mean ΔE = 11.2 [±3.11], p < 0.0001) compared to groups (b) and (c). For group (b), a significant increase in color change was measured after three (mean ΔE = 2.77 [±1.01], p = 0.02) and nine cycles (mean ΔE = 3.27 [±1.61], p = 0.006) compared to (c). Group (c) showed only minor and statistically insignificant color changes.

Conclusion This in vitro study demonstrated a significantly higher ad hoc whitening effect of the HAP gel compared to the mouth rinse and water after short-time application.

Publication History

Article published online:
13 August 2020

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