Ion-modified nanoparticles induce different apatite formation in cervical dentine

Abstract

Aim

To investigate if crystallinity and ultrastructure is modified when cervical dentine is treated with four different nanogels-based solutions for remineralizing purposes.

Methodology

Experimental nanogels based on polymeric nanoparticles (NPs) and zinc, calcium, or doxycycline-loaded NPs were applied on citric acid etched dentine to facilitate the occlusion of tubules and the mineralization of the dentine surface. Dentine surfaces were studied by X-ray diffraction and transmission electron microscopy through selected area diffraction and bright-field imaging.

Results

Crystals at the dentine surface were identified as hydroxyapatite with the highest crystallographic maturity and crystallite size in dentine treated with Zn-NPs based-gel. Texture increased in all samples from 24 h to 7 d, except in dentine surfaces treated with Zn-NPs gel. Polyhedral, plate-like and drop-like shaped apatite crystals constituted the bulk of minerals in dentine treated with Zn-NPs gel, after 7 d. Polymorphic, cubic and needle-like shaped crystals distinguished minerals, with more amorphous characteristics in dentine treated with Ca-NPs gel after 7 d than that found when Zn-NPs were applied. Doxycycline-NPs produced the smallest crystallites with poor crystallinity, maturity and chemical stability.

Conclusions

Crystalline and amorphous phases of newly formed hydroxyapatite were described in both types of dentine treated with Zn-NPs as well as Ca-NPs gels with multiple shapes of crystallites. Crystal shapes ranged from rounded/drop-like or plate-like crystals to needle-like or polyhedral and cubic apatite appearance.

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