2,2-Bis[4(2,3-hydroxypropoxy)phenyl]propane (bis-HPPP) is an organic compound that is formed when the dental composite material bis-GMA is degraded by salivary esterases. It is also called BADGE·2H2O in reference to it being the hydrolysed form of BADGE, which is used in the formation of epoxy resins. Structurally, it is a di-ether of bisphenol A.