Abstract: The present invention is directed to compounds and adhesives finding special utility in dental applications. Compounds of formulae: are of special interest, wherein: R represents a polymerizable group of the structure ?wherein R1 represents a hydrogen atom or methyl group; A represents an oxygen atom or a sulfur atom; Xqs represent independently an oxygen atom or a sulfur atom; Yqs represent independently hydrogen atom; Zqs may independently represent D-R2 where D represents a single carbon atom and R2 represents phenyl; p is an integer from 1 to 10; and q is an integer from 1 to p.

Abstract: The present invention provides an adhesive composition comprising a polymerizable phosphonic acid derivative which is a composition having intramolecularly a polymerizable group and a phosphonic acid group, represented by the general formula [1]: wherein R represents a polymerizable group; A represents an oxygen atom or a sulfur atom; Xqs represent independently an oxygen atom or a sulfur atom; Yqs represent independently the same or different organic group; Zqs may be independently the same or different from each other and, a part of the Zqs optionally selected or all of the Zqs represent organic groups having a substituent which is an organic group other than a polymerizable group and a phosphonic acid group; p is an integer from 1 to 10; q is an integer from 1 to p; when p is 1, q is 1; X1 represents an oxygen atom or a sulfur atom; Y1 represents an organic group; Z1 represents an organic group having one or more of substituents which are organic groups other than an acidic group and a polymerizab