Effect of acetic acid on the fluoride release profiles of restorative glass ionomer cements.
OBJECTIVE
This study investigates the fluoride release of glass ionomers in an acetic acid solution in order to substantiate a model according to which the short-term release results from an elution of loosely bound fluoride and the long-term release from an erosive leaching of the glass particles in the bulk of the cement.


METHODS
Individual fluoride release profiles of five specimens of 10 acid-base setting restorative glass ionomers were obtained by determining the amounts of fluoride released by each sample at 37 degrees C in consecutive elutions for up to 140 days with 25 ml of a 0.01 mol/l acetic acid solution with pH = 4. Differences in the fluoride release profiles were determined with a Multivariate Data Analysis on the basis of a Principal Component Analysis.


RESULTS
The fluoride release profiles of the 10 glass ionomers can be classified into five distinct groups which are characterized by a cumulative fluoride release described by the equation [F]c = [F]l t/(t + t1/2) + beta square root of t. The parameters ([F]l, t1/2) and beta are characteristic for the materials in the groups, and refer to the short-term and long-term fluoride release, respectively. The acidic solution enhances both processes compared to an elution in water, the effect being more pronounced for the long-term release.


CONCLUSIONS
The fluoride release mechanism is intrinsically the same as determined for elutions in water. The increased amount of fluoride released under acidic conditions, especially in the long term, corroborates that an erosive leaching of the glass particles in the bulk of the cement accounts for the long-term fluoride release.
De Moor
R J
RJ
Department of Operative Dentistry and Endodontology, University Hospital, University Gent, Belgium.
Verbeeck
R M
RM
D019342:Acetic Acid / Q000737:chemistry*; D000704:Analysis of Variance; D005459:Fluorides / Q000737:chemistry*; D005899:Glass Ionomer Cements / Q000737:chemistry*; D008422:Materials Testing; D015999:Multivariate Analysis; D012044:Regression Analysis
D005899:Glass Ionomer Cements; D019342:Acetic Acid; D005459:Fluorides