Solvent-free dental adhesive composition

A solvent-free dental adhesive composition, comprising:

• an acid group-containing polymerizable monomer (A);
• a hydrophobic polymerizable monomer (B) having no acid group;
• and
• a photopolymerization initiator (C), wherein
• the photopolymerization initiator (C) comprises at least one selected from the group consisting of a compound (C-1) of formula (1) and a compound (C-2) of formula (2):
• where R1, R2, R3, R4, R5, and R6 are each independently a linear or branched alkyl group having 1 to 4 carbon atoms or a halogen atom, X is a linear or branched alkylene group having 1 to 4 carbon atoms, and R7 represents —CH(CH3)COO(C2H4O)nCH3, where n represents an integer of 1 to 1000;
• and
• where R8, R9, R10, R11, R12, R13, R14, and R15 are each independently a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, a linear or branched alkoxy group having 1 to 4 carbon atoms, a halogen atom, —OH, or —COOY, and at least one of R8 to R15 is —COOY, where Y represents an organic cation or an inorganic cation.