Distinct decalcification process of dentin by different cariogenic organic acids: Kinetics, ultrastructure and mechanical properties

Abstract

Objectives We studied artificial dentin lesions in human teeth generated by lactate and acetate buffers (pH 5.0), the two most abundant acids in caries. The objective of this study was to determine differences in mechanical properties, mineral density profiles and ultrastructural variations of two different artificial lesions with the same approximate depth. Methods 0.05 M (pH 5.0) acetate or lactate buffer was used to create 1) 180 μm-deep lesions in non-carious human dentin blocks (acetate 130 h; lactate 14days); (2) demineralized, ~180 μm-thick non-carious dentin discs (3 weeks). We performed nanoindentation to determine mechanical properties across the hydrated lesions, and micro X-ray computed tomography (MicroXCT) to determine mineral profiles. Ultrastructure in lesions was analyzed by TEM/selected area electron diffraction (SAED). Demineralized dentin discs were analyzed by small angle X-ray scattering (SAXS). Results Diffusion-dominated demineralization was shown based on the linearity between lesion depths versus the square root of exposure time in either solution, with faster kinetics in acetate buffer. Nanoindentation revealed lactate induced a significantly sharper transition in reduced elastic modulus across the lesions. MicroXCT showed lactate demineralized lesions had swelling and more disorganized matrix structure, whereas acetate lesions had abrupt X-ray absorption near the margin. At the ultrastructural level, TEM showed lactate was more effective in removing minerals from the collagenous matrix, which was confirmed by SAXS analysis. Conclusions These findings indicated the different acids yielded lesions with different characteristics that could influence lesion formation resulting in their distinct predominance in different caries activities, and these differences may impact strategies for dentin caries remineralization.

Using Biomimetic Polymers in Place of Noncollagenous Proteins to Achieve Functional Remineralization of Dentin Tissues

“…Artificial carious lesions were prepared following methods that have been described previously in detail 39–40 . Non carious third molars were obtained from patients requiring extraction as part of their normal dental treatments following an approved protocol.…”

“…Demineralization was carried out for 66 hours based on a previously determined kinetic curve for the acetate buffer 40 .…”

Integrating the PILP-mineralization process into a restorative dental treatment

“…Artificial carious lesions approximately 140 μm deep were induced by exposing the surface to a demineralizing solution consisting of 0.05 M acetate buffer containing 2.2 mM calcium and phosphate at pH 5.0 for 66 hours, a demineralization treatment determined by prior kinetics studies [22]. After artificial caries lesions were produced, the demineralized specimens were dried gently with compressed air for 15 sec and then rehydrated with about 20 μL of deionized water for 20 sec (except Group 4), before applying the RMGI (resin-modified glass ionomer) cement, without or with additions of pAsp, to cover exposed 2.5 × 2.5mm window (Fig.…”

“…Elastic modulus and hardness of the fully demineralized outer zone recovered to about 60% of normal dentin values with PILP applications of 2 weeks, while calcium phosphate solutions alone did not produce any significant mechanical recuperation [9, 20]. The restoration of mechanical properties of the tissue is critical for regaining its function, and to date the PILP-approach appears to be the prime suitable method to reintroduce mineral into collagen fibrils and restore tissue properties, either partially or fully, thus we refer to this as functional remineralization (FR) [9, 20-22]. In addition studies on commercial silicate-based and alumo-silicate-based cements have shown promising data with regards to mineral recovery in artificial lesions but lacked evidence for a functional recovery [6, 10, 23].…”

Impact of 35% Hydrogen Peroxide on Color and Translucency Changes in Enamel and Dentin

“…Enamel is made up of more inorganic components by volume (higher than 97%) than dentin (approximately 50%). 27 The use of hydrogen peroxides over the tooth substrates reduces the mineral content due to demineralization of enamel prism and possible non-prismatic layer removal. 28 The modification on enamel surface that became more rough rises the light-diffusion and consequently decrease the light-transmission.…”