Objective: Dental hypersensitivity has become one of the most common and most costly diseases in the world, even though those maladies are very rarely life threatening. Using amorphous microparticles, fabricated from the natural polymer polyphosphate, we intend to reseal the dentinal tubules exposed and – by that – reduce the hypersensitivity of teeth.
Methods. Amorphous polyphosphate microparticles (termed aCa-polyP-MP) were prepared from Na-polyphosphate (polyP) and CaCl2, then incubated with human teeth. The potential of the microparticles to plug the dentinal tubules was determined by microscopic and spectroscopic techniques.
Results. We demonstrate that, in contrast to polyP, the aCa-polyP-MP efficiently reseal dentinal tubules exposed at the tooth surface. Scanning electron microscopical (SEM) and energy dispersive X-ray spectroscopic (EDX) studies showed that the tooth cement and dentin surfaces, incubated with aCa-polyP-MP, form a nearly homogenous, approximately 50-µm thick solid polyP layer on the tooth cement and dentin surfaces, while no coating on the tooth surface, incubated with Na-polyP, was observed. Determination of the mechanical properties of the polyP coating revealed a Martens hardness of 3.85 ± 0.64 GPa and a reduced elastic modulus of 94.72 ± 8.54 GPa already after a 3 h exposure to the aCa-polyP-MP, which become close to those of the natural enamel (4.33 ± 0.69 GPa and 101.61 ± 8.52 GPa, respectively) after prolonged incubation periods. In addition, aCa-polyP-MP turned out to display morphogenetic activity. Incubation of precursor odontoblasts in the presence of aCa-polyP-MP resulted in a 7-fold increase of the steady-state-expression level of the gene encoding for the alkaline phosphatase (ALP) during a 7 d incubation period.
Significance. Ca-polyP microparticles, consisting of the biocompatible natural polymer polyP, provide a potential sealing material for dentinal tubules on the tooth surface.