Glass ionomers bond to tooth structure by chelation of the carboxyl groups of the polyacrylic acids with the calcium in the apatite of the enamel and dentin, in a manner similar to polycarboxylate cement. The setting reaction of ZOE starts with water in the eugenol solution that hydrolyzes the zinc oxide to form zinc hydroxide. The zinc hydroxide and eugenol chelate and solidify. Ref: Phillips Ed-12th P: 331