Developing a hydrogel micro-environment for biomimetic mineralization of enamel

Abstract

Objective: To describe the effects of a novel hydrogel biomimetic mineralization micro-environment in initiating growth of enamel prisms-like crystals on human enamel surface.

Method:

Enamel slices were prepared from extracted human third molars. The outer enamel surface was polished smooth and etched with a 37% phosphoric acid. The etched enamel surface was covered by a layer of 2mm thick agarose gel containing calcium chloride. On top of the agarose gel layer, there is another layer of 2mm thick calcium ion free agarose gel. The slices, together with the agarose gel, were immersed into a freshly prepared and acidity neutral solution containing sodium dihydrogen phosphate and sodium fluoride, and incubated at 37oC for 10 days. The solution was replaced every 24 hours and the agarose gel was replaced every 48 hours. Scanning electron microscope (SEM) was used to study the crystals precipitated on enamel surface. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) were used to evaluate the chemical structure of the crystals.

Result: Observation under SEM showed crystals were precipitated and covered the enamel surface. Higher magnification (50,000x) showed that the crystals had enamel prismatic structure with the size of about 1 micrometer. They were orderly formed in bundles parallel to each other. XRD and FTIR analysis suggested that the crystals were hydroxyapatite.

Conclusion:

In this study, the novel hydrogel acts as biomimetic mineralization micro-environment to initiate growth of enamel prisms-like crystals on human enamel surface.