Influence of Thermal Treatment Conditions on the Properties of Dental Silicate Cements

Abstract

Abstract:In this study the sol-gel process was used to synthesize a precursor mixture for the preparation of silicate cement, also called mineral trioxide aggregate (MTA) cement. This mixture was thermally treated under two different conditions (1400˝C/2 h and 1450˝C/3 h) followed by rapid cooling in air. The resulted material (clinker) was ground for one hour in a laboratory planetary mill (v = 150 rot/min), in order to obtain the MTA cements. The setting time and mechanical properties, in vitro induction of apatite formation by soaking in simulated body fluid (SBF) and cytocompatibility of the MTA cements were assessed in this study. The hardening processes, nature of the reaction products and the microstructural characteristics were also investigated. The anhydrous and hydrated cements were characterized by different techniques e.g., X-ray diffraction (XRD), scanning electron microscopy (SEM), infrared spectroscopy (FT-IR) and thermal analysis (DTA-DTG-TG). The setting time of the MTA cement obtained by thermal treatment at 1400˝C/2 h (MTA1) was 55 min and 15 min for the MTA cement obtained at 1450˝C/3 h (MTA2). The compressive strength values were 18.5 MPa (MTA1) and 22.9 MPa (MTA2). Both MTA cements showed good bioactivity (assessed by an in vitro test), good cytocompatibility and stimulatory effect on the proliferation of cells.

Hydration and microhardness of mineral trioxide aggregate depending on ratio between di‐ and tricalcium silicates

“…A previous study showed that hydrated calcium silicates (calciumsilicate-hydrate, CSH) have needle-like and plate microcrystal morphologies and spongy agglomeration of carbonate phases. 25 In this study, the microstructure of 100C 3 S appeared to be more compact than that of the 100C 2 S sample. In the early stage of hydration, the newly formed CSH crystals were acicular or spongy shaped.…”

Mineralogical and Microstructural Characteristics of Two Dental Pulp Capping Materials

“…In addition, SEM images showed uniform distribution of these phases in the polymeric matrix and EDX spectrum demonstrated the presence of barium and strontium as radiopacifying elements. The diffractogram performed on BIO MTA+ anhydrous powder indicated the presence of calcium silicates as major phases—Ca 3 SiO 5 , Ca 2 SiO 4 , and Bi 2 O 3 [7,8,27,28,29]. The addition of Bi 2 O 3 is required, radiopacity being one of the basic requirements of a dental material [30], observing that hydro compounds resulting from the setting reaction are deposited on its surface.…”

“…MTA is a hydraulic cement, and a tricalcium silicate-based material. The MTA composition has predominantly Portland type I cement, which has the main crystalline solid phases: alite (tricalcium silicate, 3CaO·SiO 2 , C 3 S), belite (dicalcium silicate, 2CaO·SiO 2 , C 2 S), cellite (tetracalcium aluminoferrite, 4CaO·Al 2 O 3 ·Fe 2 O 3 , C 4 AF) and tricalcium alluminate (3CaO·Al 2 O 3 , C 3 A), with the following main oxide components: CaO, SiO 2 , Al 2 O 3 , and Fe 2 O 3 [6,7,8]. Besides this, in the MTA’s composition there are Ba and Sr oxides with opacifying roles [9].…”

“…Besides this, in the MTA’s composition there are Ba and Sr oxides with opacifying roles [9]. Following the setting reaction, called hydration, by mixing the powder with aqueous solution, compounds such as calcium hydroxide and calcium silicate hydrate are formed [7,8,9,10]. The MTA setting reaction, which can be carried out in wet environments, was one of the great advantages besides excellent biocompatibility, alkaline pH, good marginal closure, and a much lower inflammatory response than calcium hydroxide in direct pulp capping [11,12].…”

Thermal Behavior and Structural Study of SiO2/Poly(ε-caprolactone) Hybrids Synthesized via Sol-Gel Method

“…Some studies reported in the literature showed that the biological properties of the sol-gel materials were affected by the heat treatment carried out after the gel formation [ 31 , 32 , 33 , 34 , 35 ]. When the transition from sol to gel occurs, indeed, both hydrolysis and condensation reactions are incomplete and, thus, reactive silanols are still present in the system.…”