In vitro natural remineralization of enamel: characterization by conventional and synchrotron radiation-based techniques
- Autores: Sandra Diez García
- Directores de la Tesis: Ma. Jesús Sánchez Martín (dir. tes.), Manuel Valiente Malmagro (dir. tes.)
- Lectura: En la Universitat Autònoma de Barcelona ( España ) en 2021
- Idioma: inglés
- Tribunal Calificador de la Tesis: Ana Rosa Lazo Fraga (presid.), Xavier Sala Román (secret.), Raúl Ayuso Montero (voc.)
- Programa de doctorado: Programa de Doctorado en Química por la Universidad Autónoma de Barcelona
- Materias:
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- Resumen
Developing technologies to reconstruct dental enamel and restore tooth structure is of vital importance considering the inability of mature enamel to regenerate itself after substantial damage. Widespread fluoride products can prevent demineralization and promote remineralization on tooth surfaces by replacing hydroxyl ions with fluoride ions. This interaction forms more acid-resistant and stable fluorapatite in the dental enamel instead of hydroxyapatite (original natural enamel mineral).
A different approach to induce remineralization is used in the present study to avoid high concentrations of fluoride with its side effects and prolong the contact time between fluoride ions and teeth. This work aims to develop an innovative dental material to remineralize tooth enamel by a proper combination of ion-exchange resins as controlled release of mineral ions forming dental enamel, in presence of human amelogenin to guide the appropriate crystal growth. The novel product proposed consists of a combination of ion-exchange resins (weak acid and weak base) individually loaded with the remineralizing ions: Ca2+, PO43- and F-, also including Zn2+ in a minor amount as antibacterial agent, together with the protein amelogenin. Such cocktail provides onsite controlled release of the ions necessary for enamel remineralization avoiding the precipitation of undesired compounds by massive encounter of related ions outside of the enamel surface, and at the same time, a guiding tool for crystal growth by the indicated protein. Amelogenin protein is involved in the structural development of natural enamel and takes a key role in controlling the crystal growth morphology and alignment at the dental enamel surface.
Treated teeth were evaluated by using conventional techniques as well as techniques based in synchrotron light source. 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. The appropriate synchrotron data obtained, analysed with the proper chemometric method, allow us to study the evolution of the structure of apatites and their distribution after the remineralization process. Thus, we could reveal the spatial resolution required to determine the changes in the remineralization as a function of the depth thanks to the goodness of data provided by the synchrotron source, in particular the unique enhanced signal-to-noise ratio. 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 in order to determine the protein influence on the morphological changes of the remineralized enamel.
The innovative material induces the dental remineralization creating a fluorapatite layer free of carbonate impurities, with a hardness equivalent to sound enamel and the appropriate alignment of the corresponding nanocrystals thanks to amelogenin contribution, being the fluorapatite more acid-resistant than the original mineral. Our results suggest that the new product shows potential for inhibiting demineralization and promoting long-term remineralization leading to the inhibition of caries progression and protection of dental tissues structures.
