Dental composition

A dental composition comprising

• (i) an acidic polymerizable compound of the following formula (Ia), (Ib) or (Ic):
• wherein
• X which are a same or different, are bonded directly or through a methylene group to the cyclic moiety, independently represent an acidic group selected from a sulfate group, a phosphate group, a sulfonate group, a phosphonate group and a carboxylic acid group;
• Y represents, if present, a hydrogen atom, a methyl group, a hydroxyl group, an amino group, a polymerizable group, a thiol group or an amide group, each group Y is bonded directly or through a methylene group to the cyclic moiety;
• Y′ represents an OH or amide group —NH—(C═O)—R3, and
• Z represents a single bond, a carbamate group, a thiocarbamate group, a dithiocarbamate group, a urea group, a thiourea group, an amide group, an oxygen atom, a sulfur atom, or a group NR′, wherein R′ represents a hydrogen atom, a straight-chain C1-6 alkyl group, or a branched or cyclic C3-6 alkyl group which may be substituted with a phosphonate group, wherein group Z is bonded directly or through a methylene group to the cyclic moiety,
• L represents a divalent linker group;
• R2 represents a hydrogen atom, a straight-chain C1-20 hydrocarbon group, a branched or cyclic C3-20 hydrocarbon group, or a polymerizable group;
• R3 and R4 independently represent a hydrogen atom, a straight-chain C1-6 alkyl group, or a branched or cyclic C3-6 alkyl group;
• and
• (ii) an initiator system.