The effect of oxalic acid incorporation on the setting time and strength of a glass-ionomer cement.
Oxalic acid and its metal oxalate salts have been used extensively in dentistry in a range of applications: as desensitisers, in cavity preparation, and as bonding agents. This study investigated the influence of oxalic acid upon the working time, initial setting time, 24-h hardness and compressive strength of a glass-ionomer cement. Conventional glass-ionomer liquids were prepared from polyacrylic acid, tartaric acid, water, and oxalic acid at concentrations of 0-7% w/w. Liquids were dosed into capsules with a commercial glass-ionomer powder, activated and mixed. The resultant pastes were assessed for working time, initial setting time, 24-h hardness and 24-h compressive strength. Liquids containing 0.5-1% oxalic acid lengthened the working time and initial setting time. At concentrations greater than 2%, both working and initial setting times decreased with increasing oxalic acid. Surface hardness values using liquids with 3% and 7% oxalic acid were less hard than the control. Compressive strength was unchanged over the concentrations tested. Oxalic acid may be a useful reaction modifier in glass-ionomer systems. It accelerated the setting reaction without affecting strength, but was limited to low concentrations because of its relatively poor solubility in water.
Prentice
Leon Hugh
LH
School of Dental Science, University of Melbourne, Parkville, VIC. 3010, Australia.
Tyas
Martin
M
Burrow
Michael F
MF
D001696:Biomechanical Phenomena; D019245:Compressive Strength; D005899:Glass Ionomer Cements / Q000737:chemistry*; D008422:Materials Testing; D010070:Oxalates / Q000737:chemistry*; D013499:Surface Properties
D005899:Glass Ionomer Cements; D010070:Oxalates