The invention relates to a radically polymerizable monomer of formula (I)whereinW1 and W2 in each case independently represent H or X—R—Y—PG, wherein at least one of W1 and W2 represents X—R—Y—PG,X in each case independently is missing or represents an ether, ester, amide, urethane or urea group,Y in each case independently is missing or represents an ether, ester, amide, urethane or urea group,R in each case independently is missing or represents a C1-C16 alkylene radical which can be interrupted by one or more O atoms, wherein R can be missing only if X and / or Y is simultaneously also missing, andPG in each case independently represents a cyclic, ring-opening polymerizable group,a, b, c and d independently of each other can take the values 3 to 10.The invention also relates to polymerizable compositions which comprise the monomers according to the invention, as well as their use as dental materials and for the preparation of dental materials, in particular composites, cements, adhesives or coatings.