Enamel prism-like tissue regeneration using enamel matrix derivative.

BACKGROUNDS: Enamel matrix derivative (EMD) has been shown to promote periodontal regeneration, but its effect on biomimetic mineralisation of enamel is not reported. OBJECTIVES: This in vitro study aimed to investigate the effect of commercially available EMD on promoting biomimetic mineralisation in demineralised enamel using an agarose hydrogel model. METHODS: Human enamel slices were demineralised with 37% phosphoric acid for 1 min. They were covered with a 2-mm-thick EMD-calcium chloride (CaCl2) agarose hydrogel. Another 2-mm-thick ion-free agarose hydrogel was added on top of the EMD-CaCl2 hydrogel. They were incubated in a phosphate solution containing fluoride at 37 degrees C for 96 h. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD) were used to evaluate the crystals formed on the demineralised enamel surface. A nano-indenter was used to evaluate the elastic modulus and nanohardness on the surface of the enamel slices. RESULTS: SEM observed enamel prism-like crystals formed on the enamel. They had typical apatite hexagonal structures, which corroborated the enamel's microstructure. EDX revealed that the elements were predominantly calcium, phosphorus, and fluorine. XRD confirmed that they were fluorinated hydroxyapatite. The mean elastic modulus before and after remineralisation was 59.1GPa and 78.5GPa (p<0.001), respectively; the mean nanohardness was 1.1GPa and 2.2GPa, respectively (p<0.001). CONCLUSIONS: EMD promoted in vitro biomimetic mineralisation and facilitated enamel prism-like tissue formation on demineralised human enamel. CLINICAL SIGNIFICANCE: This study is the first to report on using EMD in biomimetic mineralisation, which may serve as a biomaterial for enamel repair.