Reactions in Glass Ionomer Cements: III. The Precipitation Reaction

Abstract

WVater-soluble ions in dental cements of different ages were studied. The cement is formed by the reaction between aqueous polyacrylic acid and an aluminosilicate glass.Electrical conductance measurements were made on cements up to three months after formation. Calcium polyacrylate is formed before aluminum polyacrylate. Calcium ions are fully combined within three hours, whereas aluminum ions continue to react for at least 48 hours.Wilson and Kent' have developed a dental cement using the reaction of an aluminosilicate glass and aqueous polyacrylic acid (PAA). Previous papers in this series have reported the initial attack on the glass by PAA2 and an infrared spectrometric study' of the cement reaction. The study of the reaction by chemical and electrical conductance methods is reported in this paper. All the techniques used in this series were developed previously by Wilson and Kent for investigation of the dental silicate cements.4-7Previous studies in this series showed that rapid attack of the powdered glass occurred which resulted in the release of metal cations.2 Considerably more calcium was liberated than other metal ions. The infrared spectrometric studies' showed that there is rapid production of calcium polyacrylate followed by a slower formation of aluminum polyacrylate. Other features of the cement were the presence of silica gel and free COOH groups.In this study, the water-soluble ions were extracted from cements of various ages. Thus, information unobtainable by infrared This work was carried out on behalf of the National Research Development Corporation.

The role of poly(acrylic acid) in conventional glass polyalkenoate cements

“…The strength of CGPCs increases quickly in the early stages of the reaction, within the first few days of maturation, and then increases at a slower rate over the following year [45,46]. It was first postulated by Crisp and Wilson [44] that this hardening process is based on the gelation of the polymeric acid by cross-linking, or forming inter-and intramolecular salt bridges, of the polymeric carboxyl groups with Al 3+ and Ca 2+ from the glass phase. Later in 1976, Crisp et al [46] attributed the increase in strength with time up to 1 year, to an increase in cross-link density.…”

“…The setting reaction of CGPCs is regarded as continuous and the extent to which the ionic network develops has a direct impact on mechanical properties with strengths usually developing rapidly in the first 24 h [2, [42][43][44]. The strength of CGPCs increases quickly in the early stages of the reaction, within the first few days of maturation, and then increases at a slower rate over the following year [45,46].…”

“…PAA concentration < 38% w/w resulted in no effects on the P:L ratio. Working time [38][39][40][41][42][43][44][45][46][47][48][49][50] Within this active region, increasing the PAA concentration decreased the working time. This corresponds to the increased viscosity of the cement.…”

Newer Glass Ionomer Cements having Strontium Ions and the Effect of their Release on Acidic Medium

“…13 But this liquid converts into gel form upon storage. 14 To avoid this problem, malic acid and tartaric acid were included but these additions made the setting reaction slow.…”

The response of Pseudomonas aeruginosa biofilm to the presence of a glass polyalkenoate cement formulated from a silver containing glass

“…Glass polyalkenoate cements (GPCs), formed by the reaction between an ion-leachable glass and an aqueous solution of polyacrylic acid (PAA) [12], are both antibacterial and cariostatic [13]; properties related to their ability to release beneficial amounts of therapeutic ions [14,15].…”