THE IN-VITRO COLOR STABILITY OF ACRYLIC RESINS FOR PROVISIONAL RESTORATIONS

This study made an in vitro comparative evaluation of the color variat ion of four types of acrylic resin for provisional fixed prostheses, a s determined using computerized spectrophotometry, before and after a 20- and 30-day cycle of immersion in four staining solutions. The four acrylic resins used for provisional fixed restorations were: Cold Pac , Trim, Protemp, and Mixacryl II. Thirty-two specimens for each resin were divided into four subgroups of eight elements, immersed in the fo ur staining solutions (synthetic saliva, synthetic saliva and tea, syn thetic saliva and coffee, and synthetic saliva and chlorhexidine in 0. 12% water solution), and then placed into four thermostatic baths al 3 7 degrees C +/- 1 degrees C. All specimens were measured for each resi n before immersion (baseline). After 20 and 30 days, the specimens wer e analyzed by computerized spectrophotometry and compared. All data we re analyzed with analysis of variance for repeated measures (P < .05). Only the Cold Pac resin was color stable in all staining solutions, w hile the others showed color changes from the different staining solut ions.