B

Within 24 h the acid-base reaction in conventional glass-ionomer cement is largely complete, giving it a diametral tensile strength of roughly 6–7 MPa, whereas zinc-phosphate cement levels off nearer 5–6 MPa. Laboratory studies therefore show GIC’s 24-hour tensile strength to be slightly higher than that of ZnPO₄ cement [Fonseca et al., 2007, PMID 17873972; Oilo, 1991, PMID 2032741].