5,925,690  19  20  -continued  In the third dental composition of the present invention,  the sulfonic acid group-containing monomer (F) is not  particularly limited, provided that it is a monomer having in  one molecule at least one  -S0$_{3}$H  group or group which  readily reacts with water as an essential component of the  present invention to produce a  -S0$_{3}$H  group and at least  one polymerizable unsaturated group. Known compounds  can be used as component  (F).  Typical examples of the sulfonic acid group-containing  monomer include (meth)acrylate derivatives and (meth)  acrylamide derivatives of sulfonic acid represented by the  following general formula (7), vinylsulfonic acid, styrene› sulfonic acid and the like.  wherein  R$_{1 }$ is hydrogen atom or a methyl group,  R$_{3 }$ is an  organic group having a valence of 2 to 6 and 1 to 30 carbon  atoms, which may have an ether linkage and/or an ester  linkage, Z is oxygen atom or an imino group  (-NH-),  n$_{1 }$ is an integer of 1 to 5, and n$_{3 }$ is 1 or 2.  Preferred examples of the sulfonic acid group-containing  monomer represented by the general formula (7) are as 30  follows.  A mixture of a plurality of the above sulfonic acid  group-containing monomers can be used as required.  The amount of the sulfonic acid group-containing mono- mer (F) in the present invention is preferably 0.01 to 12% by  weight, more preferably 0.5 to 10% by weight, based on the  total of all the constituent components. If the amount is  below 0.01 % by weight, the effect of improving adhesive  strength to enamel will be liable to be insufficient, and if the  amount is above 12% by weight, adhesive strength to dentin  will be liable to deteriorate.  The sulfonic acid group-containing monomer may be  mixed with the inorganic strong acid and/or the non- polymeric organic sulfonic acid illustrated as component  (E). In this case, the total amount of the inorganic strong acid  and/or the non-polymeric organic sulfonic acid is preferably  3% or less by weight, and the total amount of the inorganic  strong acid and/or the non-polymeric organic sulfonic acid  and the sulfonic acid group-containing monomer is prefer› ably 12% or less by weight.  The inorganic strong acid and/or the non-polymeric  organic sulfonic acid (E) of the second dental composition  or the sulfonic acid group-containing monomer (F) of the  third dental composition in the present invention need to be  added in a state where at least one hydrogen cation can be  supplied. When they are neutralized by a metal or amine and  added as a neutral salt, they are not component (E) or  component (F). Similarly, when a basic substance such as a  hydroxide of a metal or an amine is added as an optional  component and all or part of the acid is neutralized, the  neutralized acid is not component (E) or component (F).  In addition to the above components  (A), (B),  (C),  (D),  (E), (F) and  (G),  the dental composition of the present  invention may contain a variety of optional components to  be described later as far as they do not impair the effect of  the present invention. In this case, the weight contents of the  above components  (A), (B),  (C),  (D),  (E), (F) and  (G)  are  based on 100% by weight of the total of these components  (A), (B),  (C),  (D),  (E),  (F), (G)  and other optional compo- nents.  As  described above, the composition of the present inven› tion may contain a monofunctional monomer, a water› insoluble organic solvent, a polymerization initiator, a metal  salt, inorganic or organic fine particles and the like within  limits not prejudicial to its performance.  Illustrative examples of the monofunctional monomer  include monofunctional monomers having no acid group,  such as methyl methacrylate, ethyl methacrylate, tetrahy› drofurfuryl methacrylate, 2-ethylhexyl methacrylate,  2-hydroxylethyl methacrylate, glycidyl methacrylate,  N-methylol methacrylamide, diacetone methacrylamide and  acrylates thereof; monocarboxylic acid group-containing  monofunctional monomers such as acrylic acid, methacrylic  acid, 2-(meth)acryloyloxyethyl hydrogen malate, 2-(meth)  acryloyloxyethyl hydrogen succinate and N-(meth)acryloyl- 5-aminosalicy lie acid; and the like.  Illustrative examples of the water-insoluble organic sol› vent include hexane, heptane, octane, toluene,  dichloromethane, chloroform, carbon tetrachloride,  dichloroethane, trichloroethane, pentanone, hexanone, ethyl  formate, propyl formate, butyl formate, ethyl acetate, propyl  acetate, butyl acetate, vinyl acetate, diethyl ether and the  like.  (7) 