8 - Miscellaneous aqueous cements

Summary

General

This chapter is devoted to a miscellaneous group of aqueous acid–base cements that do not fit into other categories. There are numerous cements in this group. Although many are of little practical interest, some are of theoretical interest, while others have considerable potential as sustainedrelease devices and biomedical materials. Deserving of special mention as biomedical materials of the future are the recently invented polyelectrolyte cements based on poly(vinylphosphonic acids), which are related both to the orthophosphoric acid and poly(alkenoic acid) cements.

Miscellaneous aluminosilicate glass cements

In 1968 Wilson published an account of his early search for alternatives to orthophosphoric acid as a cement-former with aluminosilicate glasses. Aluminosilicate glasses of the type used in dental silicate cements were used in the study and were reacted with concentrated solutions of various organic and inorganic acids. Wilson (1968) made certain general observations on the nature of cement formation which apply to all cements based on aluminosilicate glasses.

(1) Silica gel is formed in the reaction but is not associated with cement formation.

(2) Water is essential to the reaction and cements are not formed when the acid is present in an organic solvent rather than in aqueous solution. Water acts as an effective reaction medium and probably hydrates reaction products.

(3) Cements are formed only with acids that are capable of forming complexes with calcium and aluminium. Thus, neither hydrochloric nor acetic acid forms cements.