Quantitative affinity parameters of synthetic hydroxyapatite and enamel surfaces in vitro

Abstract

Particulate synthetic hydroxyapatite (HAP) is rapidly gaining importance as a biomimetic agent in oral care products. The prerequisite for an adequate effect of the treatment is an efficient attachment of the HAP particles to the tooth substance. However, quantitative data about the interaction and affinity parameters involved are scarce. The authors used an in vitro approach with standardized bovine tooth enamel surfaces and aqueous dispersions of chemically pure synthetic HAP particles as a model system. Structural characterization of the HAP powder using high-resolution scanning electron microscopy (SEM) shows that the particles are micrometer-sized stable clusters of crystallites that closely resemble the structure of natural enamel. Using SEM image analysis, the authors investigated the influence of HAP particle concentration and particle size on the efficiency of attachment to bovine tooth enamel based on pure mineral-mineral interaction. The results show that both play an important role and can be tailored for optimizing the efficiency of corresponding oral care formulations. The results also reveal the presence of structures resembling mineral bridges at the interfaces between HAP particles and enamel that provide indications for possible interaction mechanisms. Notation A r aspect ratio d max crystallite length d min crystallite width N particles number of particles 141 Cite this article

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

“…4), that could be assigned to HAP since its microstructure is known and described. 10 After treatment with group (b), the enamel surface seems to be slightly smoothed by a thin layer formation compared to the initial sample surface (►Fig. 3C).…”

Ca2+ release and buffering effects of synthetic hydroxyapatite following bacterial acid challenge

“…Synthetic particulate hydroxyapatite (HAP; commercial grade; mean particle size: 4 μm) and particulate hydrated silica (SiO 2 ·nH 2 O; commercial grade; mean particle size: 12 μm) were both provided by Dr. Kurt Wolff GmbH & Co. KG (Bielefeld, Germany). A recent scanning electron microscopic structural characterization of the HAP powder used here showed that the particles are micrometersized stable clusters of crystallites resembling the structure of human enamel [21]. Hydrated silica was used as control to exclude any impairments of particulate agents on bacterial growth or biofilm formation.…”

Hydroxylapatit als biomimetischer Wirkstoff für die Remineralisation von Zahnschmelz und Dentin

“…Bei dem in Zahnpflegeprodukten verwendeten HAP, wie in einer detaillierten rasterelektronenmikroskopischen (REM) Untersuchung gezeigt, handelt es sich um stabile Mikrocluster (Partikel) von hexagonalen Kristalliten. Deren Form und Dimensionen kommen den natürlichen HAP-Kristalliten im Zahnschmelz bis auf das Fehlen einer geordneten räumlichen Anordnung sehr nahe [10]. Der Wirkstoff HAP wurde darüber hinaus unter anderem auch mittels Röntgenpulverdiffraktometrie untersucht [13,14], was die Ähnlichkeit im Vergleich zu Zahnschmelz-HAP bestätigt.…”

“…Ergänzt werden diese Arbeiten durch interdisziplinäre Grundlagenforschung und mechanistische Studien von Universitäten und Forschungseinrichtungen wie Fraunhofer-und Max-Planck-Instituten, z. B. zu den Affinitätsparametern von HAP-Partikeln und Zahnoberflächen [10,29].…”

“…Die Charakterisierung von HAP-Wirkstoffen kann mithilfe unterschiedlicher analytischer Methoden erfolgen (z. B. Röntgenpulverdiffraktometrie und REM [10,14]).…”