Highly active calcium-silicate phases for application in endodontics

Abstract

Introduction. Mineral trioxide aggregate (MTA) is one of the most commonly used materials in endodontics. Given its shortcomings, there is an intensive search for new materials. Calcium-silicate phase (CS phase) is a new material synthesized by the method based on a combination of sol-gel process and self-propagation synthesis which can significantly improve setting time through accelerated hydration. The aim of this study was to explain the mechanisms of hardening of CS phase in aqueous medium as similar mechanism is expected in contact with body fluids. Materials and Methods. CS phases Ca3SiO5 (C3S) and 2β-CaSiO4 (β-C2S) were synthesized from CaCl2·5H2O (Merck, Germany). To investigate the process of hydration, CS were mixed with water and kept at 37 °C for 28 days in closed polyethylene containers. Analysis of the composition of samples before and after immersion in water for 1, 3, 7 and 28 days was performed using X - ray diffractometry and IR. Results. XRD patterns for hydrated samples during 1, 3, 7 and 28 days showed that the amount of hydrated tobermorite phases relative to the amount of CS phase changes with the time of hydration. After 1 day, in addition to the hydrated phases, a significant amount of untransformed β-C2S and C3S were found while after 28 days hydrated CS phase was completely transformed to tobermorite with a small amount of portlandite. Conclusion. Using combined method of sol-gel and self-propagating waves at high temperature very active nanostructured silicate phases were obtained. Hydration process of CS phases was analyzed using XRD and FTIR, the mechanism of hydration was proposed and it was pointed to the difficulties in determining the exact reaction as well as the problem of determining the exact structure of tobermorite.

Uvod. Mineral trioksidni agregat (MTA) je jedan od najčešće korišćenih materijala u endodonciji. S obzirom na njegove nedostatke, intenzivno se traga za novim materijalima. Kalcijum-silikatna faza (CS faza) je novi materijal sintetisan prema metodi zasnovanoj na kombinaciji sol-gel procesa i samoprenosivoj sintezi koja može značajno poboljšati vreme vezivanja kroz ubrzanu hidrataciju. Cilj ove studije je bio da objasni mehanizme otvrdnjavanja CS faze u vodenom medijumu budući da se sličan mehanizam očekuje u kontaktu s telesnim tečnostima. Materijal i metode rada. CS faze Ca3SiO5 (C3S) i 2β-CaSiO4 (β-C2S) su sintetisane iz CaCl2·5H2O (Merck, Nemačka). Da bismo istražili proces hidratacije, CS su pomešani s vodom i ostavljeni 28 dana na 37°C u zatvorenim polietilenskim kontejnerima. Analiza sastava uzoraka pre potapanja u vodu i jedan dan, tri, sedam i 28 dana nakon potapanja izvršena je difraktometrijom radioloških zraka i FTIR. Rezultati. XRD obrasci za uzorke hidratisane tokom jednog, tri, sedam i 28 dana pokazuju da se količina hidratisane faze tobermorita u odnosu na količinu faze CS menja s vremenom hidratacije. Kod uzorka hidratisanog jedan dan, pored hidratisane faze tobermorita, utvrđene su i značajne količine β-C2S i C3S koje su ostale netransformisane, da bi kod uzoraka hidratisanih 28 dana CS faza bila potpuno transformisana u tobermorit uz male količine portlandita. Zaključak. Pomoću kombinovane metode sol-gel i metode samopropagirajućih talasa na visokoj temperaturi dobijene su veoma aktivne nanostrukturne silikatne faze. Proces hidratacije CS faza je analiziran pomoću XRD i FTIR, predložen je mehanizam hidratacije i ukazano na teškoće u utvrđivanju tačne reakcije, kao i na problem utvrđivanja tačne strukture tobermorita.