Mineral trioxide aggregate (MTA) cement is an attractive material in endodontic dentistry. The purpose of this study was to produce calcium silicate, which is a major component of MTA, from waste materials. A dental alginate impression gel and used chalks were selected and mixed in a suitable ratio (Code: EXP). As a control, CaCO3 and a commercial diatomite were used (Code: CON). Each powder was heated to 850˚C and 1000˚C, and then kneaded with water. TG-DTA, compressive tests, SEM observations, elemental mapping analyses, and XRD analyses were performed. TG-DTA indicated that weight reduction of CaCO3 started at 600˚C, and it completely decomposed on heating at 850˚C. The strength was affected by the temperature. After heating, CaCO3 was transformed into CaO and/or Ca2SiO4, and Ca(OH)2 was formed by mixing with water. There were no differences between EXP and CON. These data suggested that recycled wastes might be promising MTA sources.

The purpose of this study was to synthesize biomaterials from daily dental waste. Since alginate impression material contains silica and calcium salts, we aimed to synthesize calcium silicate cement from alginate impression material. Gypsum-based investment material was also investigated as control. X-ray diffraction analyses revealed that although fi ring the set gypsum-based and modifi ed investment materials at 1,200°C produced calcium silicates, fi ring the set alginate impression material did not. However, we succeeded when fi ring the set blend of pre-fi red set alginate impression material and gypsum at 1,200°C. SEM observations of the powder revealed that the featured porous structures of diatomite as an alginate impression material component appeared useful for synthesizing calcium silicates. Experimentally fabricated calcium silicate powder was successfully mixed with phosphoric acid solution and set by depositing the brushite. Therefore, we conclude that the production of calcium silicate cement material is possible from waste alginate impression material.

In a previous study, the authors tried to synthesize dental materials from dental waste, which was accomplished with alginate impression materials and gypsum. A powder was set by mixing it with phosphate solution. Fibrous curled crystals were found through SEM observation. The present study shows a detailed analysis of the crystals. XRD analysis indicated the crystals are Brushite. A unique profile of the crystal shows it can be a good apatite precursor or cell scaffold; however, this hypothesis requires further examination

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Using Polyphosphate, Calcium mixture and water, causes pure single apatite crystal by hydrothermal synthesis.