ポルトランドセメント
Portland cement is a term applied to a class of materials covering a range of compositions (between silica alumina and calcia). The composition, fineness, setting time and strength of Portland cement are not controlled or guaranteed. Portland cement is an unsuitable substitute for MTA based on several characteristics that are essential to the performance: freedom from heavy metals, dimensional stability and fineness. The FDA requires dental materials to have high purity and be lead and arsenic-free, unlike commercial Portland cement.