Abstract: A dental polymerizable and curable composition that can be used as a dental composite restorative featuring excellent handling property at the time of filling, a small contraction upon polymerization, a high bending strength, excellent surface smoothness and wear resistance, and a very good matching of color tone to the natural tooth after restored.

Abstract: A dental catalyst for chemical polymerization comprising an acidic compound, an organic peroxide such as cumene hydroperoxide, and aryl borate compound such as sodium tetraphenylborate, but without substantially containing amine compound. This catalyst is chemically highly stable, is easy to handle, is highly active, is less likely to be impaired by polymerization, and does not cause the cured product to be tinted or discolored, and is very useful for the dental restorative.

Abstract: A visible-ray polymerizable composition comprising:(1) a monomer comprising a (meth)acrylate monomer; and(2) a visible-ray polymerization initiator comprising:(A) a coumarin dye;(B) at least one photo acid generator selected from the group consisting of a halo-alkyl substituted s-triazine derivative and a diphenyliodonium salt compound; and(C) an aryl borate compound.

Abstract: A polymerizable composition containing;(A) 100 parts by weight of a vinylbenzyl compound of the formula (I), ##STR1## wherein each of R.sup.1 and R.sup.2 is independently a halogen atom, each of h and i is independently 0, 1 or 2, each of X.sup.1, X.sup.2 and X.sup.3 is independently an oxygen atom or a sulfur atom, and each of j, k and m is 0 or 1, provided that when k is 0, j is 0, that when m is 0, each of j and k is 0, that when j is 0 and when each of k and m is 1, X.sup.1 and X.sup.2 cannot be sulfur atoms at the same time, and that when each of m, k and j is 1, X.sup.1, X.sup.2 and X.sup.3 cannot be sulfur atoms at the same time,and(B) 0.1 to 20 parts by weight of 2,4-diphenyl-4-methyl-1-pentene.