An aqueous dental glass ionomer composition comprising (a) a reactive particulate glass, (b) a linear or branched polymer comprising acidic groups, which is reactive with the particulate glass in a cement reaction, whereby the linear or branched polymer comprising acidic groups has a polymer backbone and optionally pendant groups, (c) optionally dispersed nanoparticles comprising grafted linear or branched polymer chains comprising acidic groups, and having a polymer backbone characterized in that a polymer backbone of the linear or branched polymer of component (b) and/or, if present, the grafted linear or branched polymer chains of component (c) are obtainable a process comprising (i) cyclopolymerizing or cyclocopolymerizing one or more compounds of the following formula (I):
