Characterization of Experimental Dental Cements Derived from Locally Available Aluminosilicate Materials in Kenya

Abstract

An evaluation of locally available alkali-activated aluminosilicates (geopolymers) and clinker was carried out for the purpose of establishing a substitute material for development of atraumatic restorative treatment (ART) cements. Materials were obtained from local Portland cement manufacturers. Compositional analysis was carried out by Graphite Furnace Atomic Absorption Spectroscopy (GFAAS), X-ray Fluorescence (XRF), X-ray diffraction (XRD) and Fluoride Selective Electrode meter while Laser diffraction was used for particle size analysis (LDPSA) after sieving through a 53µm sieve. Geopolymers and clinker (0.5-1g) were mixed with freeze-dried poly(acrylic-acid) (0.1-0.2g) and aqueous tartaric acid (0.15-0.25mL) to produce cements whose setting time and compressive strength in 100% humidity was assessed after 1, 3 and 7d. Mineral trioxide aggregate (MTA) and glass ionomer cements (GIC) were used as controls. Geopolymers, clinker and MTA were found to contain varying ratios of SiO2 (18-74wt%), CaO (1-65wt%), Al2O3 (2-27wt%) and similar diffraction peaks of CaCO3, 2CaO.SiO2 and 3CaO.SiO2. MTA was found to contain Bi2O3 (16-33wt%) and Pb (1-2wt%), while geopolymers and clinker contained <0.001wt% Pb. Two geopolymers contained F- (5.99- 43.33µg/g). LDPSA reported an average particle size of 45 µm or less. The average mixing time was 1min while setting time ranged from 1.5-8min. All cements except those based on kaolin softened in distilled water at earlier time points but seemed to harden again after 28d. However, the kaolin cements exhibited the lowest CS (<5MPa) while one of the clinkers had CS of 14MPa after 28d.