The relation between thermal and pH changes in alginate impression materials.
OBJECTIVE
The purpose of this study was to determine if pH changes are related to thermal changes during setting in alginate impression materials, and to investigate the possibility of establishing a mathematical model between thermal and pH changes.


METHODS
Thermal and pH changes were recorded during the 20 min gelation period following the mixing of five commercial alginate materials. The data obtained were plotted and statistically analyzed using a student's T-test, multiplicative, linear and reciprocal analyses at a significance level of p<0.05. These analyses were used to determine the differences between various materials and to establish regression models between thermal and pH changes for each of the materials tested.


RESULTS
For all samples, the pH values fell within the first minutes from the alkaline range into the neutral and even into the acidic range, while the initial sharp fall in temperature was followed by a subsequent gradual increase. Differences in the final gel structures of the alginate materials were shown to be related to the differences in thermal and pH changes during setting. This could be expected from their various chemical compositions such as the variety of components, the chemical forms of principal components and the proportion of each component.


CONCLUSIONS
This work contributes to the development of a mathematical model relating pH changes and thermal changes to form a basis for the correlation between chemical properties and characteristics in practical use.
Anastassiadou
V
V
Department of Removable Prosthodontics, Faculty of Dentistry, Aristotle University of Thessaloniki, Greece.
Dolopoulou
V
V
Kaloyannides
A
A
D000464:Alginates / Q000737:chemistry*; D002133:Calcium Sulfate / Q000737:chemistry; D003760:Dental Impression Materials / Q000737:chemistry*; D005782:Gels / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D016014:Linear Models; D008956:Models, Chemical; D012044:Regression Analysis; D013696:Temperature; D013997:Time Factors
D000464:Alginates; D003760:Dental Impression Materials; D005782:Gels; D002133:Calcium Sulfate