EFFECT OF EARLY WATER CONTACT ON SOLUBILITY OF GLASS-IONOMER LUTING CEMENTS

Statement of problem. Glass ionomer cements are susceptible to attack by moisture during the initial setting period that can result in an in creased solubility. Purpose. This study was to evaluate the solubility of glass ionomer luting cements immersed in distilled water at early stages after mixing. Material and methods. Four commercial glass ionom er cements were used (Ketac-Cem, Fuji Ionomer I; AquaCem; AquaMeron). For each material, 5 resin cement holders were made with 2 circular ca vities (diameter = 5 mm; depth = 2 mm). One minute after start of mixi ng, the specimens were placed in a humidifier at 37 degrees C and 100% relative humidity. After 2, 5, and 8 minutes storage time, they were immersed in 50 mL of distilled water in a glass weighing bottle where they were stored for 3 hours at 37 degrees C. Next, the specimens were removed and the water was evaporated from the weighing bottle at 130 degrees C for 2 hours. The difference between the final and initial we ights of the bottle was taken as amount of solubility. Data were analy zed by analysis of variance and Duncan's test. Results. Solubility was greatest at 3 minutes immersion time and least at 9 minutes. The lowe st cement loss was for AquaCem at 9 minutes immersion time (1.68 mg/cm (2)). The greatest loss was for Fuji Ionomer I after 3 minutes immersi on time (14.98 mg/cm(2)). Solubility of cements decreased by 39% for K etac-Cem, 61% for Fuji Ionomer I, 38% for AquaCem, and 37% for AquaMer on when the specimens were immersed in water 6 minutes after mixing. C omparison of all 4 cements revealed a relatively large difference betw een loss of substance from AquaCem and AquaMeron, and the 2 other conv entional glass ionomer cements, Ketac-Cem and Fuji Ionomer I. Conclusi ons. Increasing the time from start of mixing until immersion in water from 3 to 9 minutes resulted in a marked decrease in loss of substanc e from the surface of all 4 cements. Water-hardening glass ionomer cem ents (AquaCem and AquaMeron) were less sensitive to early water contam ination.