Dental composition comprising(i) 5 to 80 percent by weight based on the total weight of the composition of a polymerizable matrix containing polymerizable monomers；(ii) a polymerization initiator system containing(a) an alpha-diketone photoinitiator compound having a light absorption maximum in the range from 300 to 500 nm； and(b) a coinitiator compound of the following formula (I): A-H (I)wherein A is a moiety of the following formula (II) R1R2R3X- (II)whereinXrepresents Si, Ge, or Sn andR1represents a hydrogen atom, an organic moiety or a different moiety A；R2 and R3which are independent from each other, represent an organic moiety.
