Dental materials with light-induced reversible coloring

A radically polymerizable dental material comprising at least one compound of Formula (I),

• in which the variables have the following meanings:
• X, Y in each case are S;
• R1,R2 in each case are methyl;
• R5;R6 together form a —(CH2)n— group, wherein n is 3 and wherein in the —(CH2)— group one or more H atoms can be replaced by F;
• R7,R9 independently of each other in each case are H or a C1-C3 alkyl radical;
• R8, R10 independently of each other in each case are a C1-C6 alkyl radical, which can be interrupted by O or —O—C(═O)—NH— and which carries a terminal radically polymerizable group, wherein the polymerizable group is selected from vinyl, styryl, acrylate, methacrylate, acrylamide, N-alkylacrylamide, and methacrylamide, and
• at least one radically polymerizable monomer and at least one initiator for radical polymerization.