Effect of biomimetic mineralization on enamel and dentin: A Raman and EDX analysis

Abstract

Objective: To investigate the effect of an experimental biomimetic mineralization kit (BIMIN) on the chemical composition and crystallinity of caries-free enamel and dentin samples in vitro.

Methods: Enamel and dentin samples from 20 human teeth (10 for enamel; 10 for dentin) were divided into a control group without treatment and test samples with BIMIN treatment. Quantitative analysis of tissue penetration of fluoride, phosphate, and calcium was performed using energy-dispersive X-ray spectroscopy (EDX). Mineralization depth was measured by Raman spectroscopy probing the symmetric valence vibration near 960cm^-1 as a marker for crystallinity. EDX data was statistically analyzed using a paired t-test and Raman data was analyzed using the Student's t-test.

Results: EDX analysis demonstrated a penetration depth of fluoride of 4.10±3.32μm in enamel and 4.31±2.67μm in dentin. Calcium infiltrated into enamel 2.65±0.64μm and into dentin 5.58±1.63μm, while the penetration depths for phosphate were 4.83±2.81μm for enamel and 6.75±3.25μm for dentin. Further, up to 25μm of a newly mineralized enamel-like layer was observed on the surface of the samples. Raman concentration curves demonstrated an increased degree of mineralization up to 5-10μm into the dentin and enamel samples.

Significance: Biomimetic mineralization of enamel and dentin samples resulted in an increase of mineralization and a penetration of fluoride into enamel and dentin.

Keywords: Biomimetic; Dentin; EDX; Enamel; Mineralization; Raman.

Figure 1:

SEM of representative enamel (A, C) and dentin samples (B, D). The enamel-like layer is visible on the surface of the treated samples. In dentin, the new mineral is also detectable in the tubules. Figures show the results after one (A, B) and five repeated applications (C, D) of BIMIN.

Figure 2:

SEM/EDX output of representative enamel and dentin samples after a 5-fold BIMIN application. Mass % of several elements (only results of fluoride, phosphate, and calcium are presented in the text) per measurement line (30 μm). From left to right: the first dotted line (x₀) separates the BIMIN layer from the sample surface and the second dotted line (x_p) limits the penetration zone in the tooth structure.

Figure 3:

Raman spectra from 350 to 1800 cm⁻¹ of dentin (top), enamel (middle) and BIMIN (bottom). Labeled bands are discussed in the text. Spectra are shifted to avoid overlap.

Figure 4:

Photomicrographs of dentin and enamel without and with BIMIN treatment (top row). Intensity of hydroxyapatite (gray trace) and BIMIN (black trace) components after multivariate curve resolution (MCR) analysis (middle row). Full width at half maximum of hydroxyapatite band near 960 cm⁻¹ [30]. The distributions are plotted as a function of the lines from 0 to 50 μm.