Colour stability of heat and cold cure acrylic resins.
BACKGROUND
To evaluate the colour stability of heat and cold cure acrylic resins under simulated oral conditions with different colorants.


METHODS
Three different brands of heat cure acrylic resin and two rapid cure auto polymerizing acrylic resin of commercial products such as Trevelon Heat Cure (THC), DPI Heat cure (DHC), Pyrax Heat Cure (PHC), DPI Cold cure (DCC) and Acralyn-R-Cold cure (ACC) have been evaluated for discoloration and colour variation on subjecting it to three different, commonly employed food colorants such as Erythrosine, Tartarizine and Sunset yellow. In order to simulate the oral condition the food colorants were diluted with artificial saliva to the samples taken up for the study. These were further kept in an incubator at 37°C ± 1°C. The UV-visible spectrophotometer has been utilized to evaluate the study on the basis of CIE L* a* b* system. The prepared samples for standard evaluation have been grouped as control group, which has been tested with a white as standard, which is applicable for testing the colour variants.


RESULTS
The least colour changes was found to be with Sunset Yellow showing AE* value of 3.55 with heat cure acrylic resin branded as PHC material and the highest colour absorption with Tartarizine showing AE* value of 12.43 in rapid cure autopolymerzing acrylic resin material branded as ACC material.


CONCLUSIONS
ACC which is a self cure acrylic resin shows a higher colour variation to the tartarizine food coloration. There were not much of discoloration values shown on the denture base resins as the food colorants are of organic azodyes.
Professor, Department of Prosthodontics, Madha Dental College , Chennai, India .
Pavan Kumar
PK
Bohra
Professor and Head, Department of Prosthodontics, Madha Dental College , Chennai, India .
P R
PR
Ganesh
Professor and Head, Department of Prosthodontics, Teja Dental College , Tirupati, India .
Madan Mohan
MM
Reddy
Professor, Department of Conservative Dentistry and Endodontics, Madha Dental College , Chennai, India .
A V Rajesh
AV
Ebenezar
Professor and Head, Department of Oral Pathology and Oral Microbiology, Madha Dental College , Chennai, India .
G
G
Sivakumar
Calorimetry; Colorants; Heat cure acrylic resins; Self cure acrylic resins; Spectrophotometer