Color Stability of Compomer after Immersion in Various Media

Purpose: The purpose of this study was to evaluate the effect of various media on the color stability of compomer and to compare these results to those of other materials that could be used in similar clinical circumstances.
Materials and Methods: In this test, six materials (shade A2) were used: four compomers (Dyract, Compoglass F, Xeno, F2000), one composite resin (Clearfil AP-X), and one resin-modified glass ionomer cement (Fuji II LC). There were four test solutions: one alcoholic (whiskey), two low pH soft drinks (Coca Cola, orange juice), and deionized water as a control. A plastic ring mold (9-mm diameter x 1-mm height) was used to prepare 120 disk specimens. For 60 days, the test specimens were immersed in the various media daily for 3 hours then transferred to the deionized water. Color was measured by CIE L* a* b* relative to CIE source against a white background, using a colorimeter. Color change (Δ*) was calculated as Δ*= [(δ*)²+ (δ*)²+ (Δ*)²]^1/2. Color changes (Δ*) were recorded after 1, 7, 30, and 60 days.
Results: The results indicated that compomer and resin-modified glass ionomer were susceptible to discoloration in various solutions over an extended period of time. Composite resin showed minimal perceptible color change. Specimens immersed in whiskey showed a significantly high perceptible color change (p < .0001). Water caused no perceptible color changes.
CLINICAL SIGNIFICANCE
Compomer and resin-modified glass ionomer materials are susceptible to discoloration by various media.     

Effect of Alcoholic and Low-pH Soft Drinks on Fluoride Release from Compomer

Purpose: The purpose of this study was to evaluate the amount of fluoride released from compomer restorative materials after immersion in various media. Materials and Methods: In this test, four materials were used: three compomers (Dyract, Dentsply, Konstanz, Germany; Compoglass, Vivadent, Schaan, Principality of Liechtenstein; and Xeno, Sankins, Tochigi, Japan) and one resin‐modified glass ionomer cement (Fuji II LC, GC, Tokyo, Japan). There were four test solutions: one alcoholic (whiskey), two low‐pH drinks (Coca‐Cola, orange juice), and one deionized water. Over a period of 60 days, the tested specimens were immersed in the test solution for 3 hours every day, then kept in deionized water. The fluoride released was detected by using a fluoride ion selective electrode connected to a microprocessor ion analyzer. The fluoride ion concentration (ppm) of the test solutions and deionized water was recorded after 1, 2, 3, 4, 7, 30, and 60 days. Electron probe microanalysis was used for surface analysis of the fluoride released. Results: When immersed in low‐pH soft drinks, compomer showed a significantly higher fluoride release than when immersed in deionized water (p <.0001). For specimens immersed in Coca‐Cola, the fluoride release levels (pg/cm², mean ± SD) at 1, 7, and 60 days for Dyract (91.6 ± 1.8, 39.3 ± 3.1, 10.5 ± 0.9), Compoglass (129.5 ± 0.9, 66.5 ± 2.7, 19.0 ± 0.3), Fuji II LC (147.0 ± 4.2, 50.8 ± 3.1, 27.6 ± 3.0), and Xeno (73.6 ± 3.2, 27.3 ± 2.1, 6.6 ± 0.6) demonstrated the trend of significantly lower releases with time in water solution. Over a 60‐day period, materials immersed in 100% orange juice released the highest amount of fluoride, which could be attributable to the erosive effect of the medium. Materials immersed in deionized water released the least amount of fluoride. Among the tested compomers, Compoglass released the most fluoride. CLINICAL SIGNIFICANCE The results of this study indicate that, at low pH, compomer restorative materials tend to release more fluoride.