Synthesis of novel sol-gel based hydraulic and bioactive endodontic cements

Abstract

Oral diseases remain the most prevalent conditions worldwide. Bioactive endodontic cements (BECs) have a major impact on clinical use and have garnered considerable attention in the research of new and more advanced endodontic treatments. However, there are several issues, such as long setting time, handling difficulties, and tooth discoloration, that require enhancement. The sol-gel process is a wet chemical method that allows very fine control over the composition, microstrucuture, and final textural properties of materials, and has great potential for the synthesis of endodontic cements with improved properties. The main objective of this doctoral thesis has been to develop hydraulic and bioactive endodontic cements with improved properties using the sol-gel technique. In Chapter 1, the research work’s background is first reviewed, followed by a summary of the uses of calcium silicate bioceramics in current dental therapies. Moreover, the latest advancements in the synthesis of this bioceramic using sol-gel method are also discussed from three perspectives: compositions and synthesis routes, materials processing, and therapeutic and clinical applications. In Chapter 2, the study examines the impact of various sol-gel synthesis parameters on the preparations of BEC materials. Following the identification of the most optimal hydraulic compositions, a new secondary post-synthesis treatment involving ethanol is investigated. Through characterization techniques such as XRD, FTIR, SEM&EDX, the findings demonstrate the effectiveness of the sol-gel method in producing BECs with high content of hydraulic compound C3S in its triclinic polymorph. The implementation of a novel post-synthesis treatment allows obtaining a final BEC product with a finer particle size and increased CaCO3 content, leading to improved material properties in terms of setting time and bioactive response. In Chapter 3, the study examines the synthesis of Zn-inclusive BEC formulations with specific functionalities due to its antibiotic and biomineralization promoting properties. Zn-BEC formulations with Zn content ranging from 1% to 5% molar are selected for further characterization in terms of hydration performance and bioactivity. The addition of Zn leads to an increase in the hydraulic compound C3S content, a reduction in β- C2S and CaO, and the stabilization of the C3S polymorph from triclinic to monoclinic. It is found that a moderate amount of Zn incorporation does not adversely impact on the hydration performance and bioactivity of Zn-BECs. Finally, in Chapter 4, a structure-directing agent is introduced to the synthesis route to enhance the textural properties, such as surface area and nanoporosity, which are correlated with shorted setting times. The resulting materials consist of hydraulic β- C2S and CaO with a monodisperse population of nanoporosity, leading to improved textural characteristics and decreased setting times.

Las enfermedades bucodentales siguen siendo las afecciones más prevalentes en todo el mundo. Los cementos endodónticos bioactivos (BECs) tienen un gran impacto en el uso clínico y han atraído considerable atención en la investigación de tratamientos endodónticos nuevos y más avanzados. Sin embargo, hay varios problemas, como el tiempo prolongado de fraguado, las dificultades de manipulación y la decoloración de los dientes, que requieren mejora. El proceso sol-gel es un método químico húmedo que permite un control muy fino sobre la composición, microestructura y propiedades texturales finales de los materiales, y tiene un gran potencial para la síntesis de cementos endodónticos con propiedades mejoradas. El principal objetivo de esta tesis doctoral ha sido desarrollar cementos endodónticos hidráulicos y bioactivos con propiedades mejoradas mediante la técnica sol-gel.