Glass inomer / dental implant courses by Indian dental academy

Page 1

Introduction

Glass ionomer cements were introduced by Wilson and Kent in 1972.1

Their development arose from the research into silicate and

polycarboxylate cements. This material has unique properties, such as chemical adhesion to moist tooth structure, anticariogenic due to fluoride release and biocompatibility. This tooth colored restorative material is becoming increasingly popular in recent years. Water plays an important role in the setting reaction and cement structure of glass ionomer cement. Water lost during the early setting reaction, may stop the reaction resulting in surface crazing.

Water

sorption on the other hand will lead the cement to loose its translucency.7 In essence, glass ionomer cements form a class of materials known as acid-base reaction cements. Initial setting occurs in 3-4 minutes, but precipitation, gelation and hydration occurs for atleast 24 hours and setting continues slowly for much longer periods.1 These materials set and harden by a transfer of metal ions from the glass to the polyacrylic acid to form a salt hydrogel which is the binding matrix. Water is the reaction medium and also serves to hydrate the silicious hydrogel and the metal polyalkeonate that are formed. It is an essential part of the cement structure.

Therefore the water balance must be controlled to permit

1


Turn static files into dynamic content formats.

Create a flipbook
Issuu converts static files into: digital portfolios, online yearbooks, online catalogs, digital photo albums and more. Sign up and create your flipbook.