Combination of Two Synchrotron Radiation-Based Techniques and Chemometrics to Study an Enhanced Natural Remineralization of Enamel

Abstract

The limitations to assess dental enamel remineralization have been overcome by a methodology resulting from the appropriate combination of synchrotron radiation-based techniques on both, infrared microspectroscopy and micro X-ray diffraction, with the help of specific data mining. Since amelogenin plays a key role in modulating the mineralization of tooth enamel, we propose a controlled ion release for fluorapatite structural ions (Ca 2+ , PO 4 3– , and F – , also including Zn 2+ ) by using weak acid and weak base ion-exchange resins in the presence of amelogenin to remineralize the surface of etched teeth. This combination provides the necessary ions for enamel remineralization and a guide for crystal growth due to the protein. Remineralized tooth samples were analyzed by applying the indicated methodology. The synchrotron data were treated using principal component analysis and multivariate curve resolution to analyze the mineral layer formed in the presence and absence of amelogenin. The remineralizing treatment created a fluorapatite layer free of carbonate impurities and with a similar orientation to that of the natural enamel thanks to amelogenin contribution.

Development of a Hybrid Biomimetic Enamel-Biocomposite Interface and a Study of Its Molecular Features Using Synchrotron Submicron ATR-FTIR Microspectroscopy and Multivariate Analysis Techniques

“…Subsequent processes of the redeposition of HAp nanocrystals with the formation of a non-apatite environment led to the appearance of a maximum in the spectra of the S IV sample clusters in the infrared spectrum near 1107 cm −1 . A similar result was described in [ 92 ], and this oscillation near 1090–1110 cm −1 can be attributed to the vibration of the secondary Ca-O-P phase [ 91 , 93 ]. Thus, the use of amino acids and an alkaline solution for pretreatment and biointerface formation results not only in an excess of calcium in the hybrid transition layer but also in the creation of the conditions for calcium binding to phosphate complexes (HPO 4 and PO 4 ) [ 94 ].…”

Acquisition and evaluation procedure to improve the accuracy ofSAED

“…Texture, its orientation and magnitude can be determined from SAED data not only for 002 (Figure 7a texture, the other (B) originates from another coexisting crystallite orientation population in the studied volume. These results can be discussed in comparison to synchrotron measurements (e.g., Al-Jawad et al, 2012;Al-Mosawi et al, 2018;Diez-García et al, 2022), however, at higher spatial resolution and combined with high resolution imaging. Furthermore, as molecular dynamics simulations prove that variation of crystallite orientation on the sub-micrometer scale strongly affects mechanical properties of dental enamel (Beniash et al, 2019), it is presumed that such findings will contribute to the interpretation of hardness variations measured in dental enamel cross section (Kis et al, 2021).…”

Synchrotron X-ray Studies of the Structural and Functional Hierarchies in Mineralised Human Dental Enamel: A State-of-the-Art Review

“…Demineralised enamel exposed to salivary proteins was also studied [ 328 ]. Remineralisation studies have been performed in bovine enamel, where WAXS analysis was carried out after treatment of fluoride-containing dentifrices and using the analysis of the (001) peak as a function of depth [ 568 ], for the characterisation of fluorapatite (where a shift in the diffraction pattern observed) [ 569 ]; and the study of the biomimetic composite crystal structure [ 570 ] and the reflection and intensity of the diffraction peaks of the biomimetic materials compared to reference hydroxyapatite suggested the formation of crystals along the c axis.…”

“…Synchrotron infrared spectroscopic ellipsometry was carried out on demineralised and remineralised dentine and enamel [ 419 ], and variations in the spectra were observed with a different remineralised solution. Specular reflectance synchrotron micro FTIR was also carried out, to study the remineralisation of bovine enamel, to determine the carbonate substitution [ 569 ]. The new layers formed during the remineralisation were analysed, the presence of the phosphate group in the spectra acquired in each new layer was identified, and there was a lower intensity of the peaks carbonate group than in the control sample.…”