Temperature and curing time affect composite sorption and solubility

OBJECTIVE This study evaluated the effect of temperature and curing time on composite sorption and solubility. MATERIAL AND METHODS Seventy five specimens (8×2 mm) were prepared using a commercial composite resin (ICE, SDI). Three temperatures (10°C, 25°C and 60°C) and five curing times (5 s, 10 s, 20 s, 40 s and 60 s) were evaluated. The specimens were weighed on an analytical balance three times: A: before storage (M1); B: 7 days after storage (M2); C: 7 days after storage plus 1 day of drying (M3). The storage solution consisted of 75% alcohol/25% water. Sorption and solubility were calculated using these three weights and specimen dimensions. The data were analyzed using the Kruskal-Wallis and Mann-Whitney U Tests (α=5%). RESULTS The results showed that time, temperature and their interaction influenced the sorption and solubility of the composite (p<0.05). At 60°C, the composite sorption showed an inverse relationship with the curing time (p<0.05). The composite cured for 5 s showed higher sorption for the 40 s or 60 s curing times when compared with all temperatures (p<0.05). Curing times of 20 s and 40 s showed similar sorption data for all temperatures (p>0.05). The 60°C composite temperature led to lower values of sorption for all curing times when compared with the 10°C temperature (p<0.05). The same results were found when comparing 10°C and 25°C (p<0.05), except that the 20 s and 40 s curing times behaved similarly (p>0.05). Solubility was similar at 40 s and 60 s for all temperatures (p>0.05), but was higher at 10°C than at 60°C for all curing times (p<0.05). When the composite was cured at 25°C, similar solubility values were found when comparing the 5 s and 10 s or 20 s and 40 s curing times (p>0.05). CONCLUSION In conclusion, higher temperatures or longer curing times led to lower sorption and solubility values for the composite tested; however, this trend was only significant in specific combinations of temperature and curing times.