EFFECT OF DESICCATION ON MICROLEAKAGE OF 5 CLASS-5 RESTORATIVE MATERIALS

Resin-modified glass ionomers, combinations of resin and glass-ionomer chemistry, have resulted in materials with longer working times and c ommand set by visible light activation. These materials are easier to use and more resistant to early moisture contamination and fracture. A glass-ionomer or resin-modified glass-ionomer restoration may be inad vertently desiccated by isolation of the same quadrant for subsequent restorative procedures. The present study is an assessment of the effe cts of desiccation on microleakage of three resin-modified glass-ionom ers: Vitremer, Photac-Fil, Fuji II LC; a glass-ionomer, Ketac-Fil; and a microfill resin, Silux Plus. Fifty extracted molars were prepared w ith class 5 preparations buccal and lingual and randomly assigned to 1 0 groups (n=10). Restorations were placed according to the manufacture rs' specifications and finished wet after the manufacturers' specified setting interval. All samples were thermocycled 300 cycles between 50 and 500 degrees C. Samples were stored in water at all times until th e five groups to be desiccated were air dried and stored dry for 45 mi nutes. Desiccated groups were then rehydrated for 24 hours prior to Ag NO3 staining. Teeth were sectioned mesiodistally and four buccolingual sections (0.6 mm thick) through each class 5 restoration were obtaine d with a Silverstone-Taylor hard tissue microtome. Each section was sc ored on a scale of 0-4 for microleakage, and the highest score for dye penetration was used as the score for that restoration. An increase i n microleakage was observed in all desiccated groups. Three materials showed a statistically significant increase in microleakage (P < 0.05) following desiccation. Microleakage increases following a brief perio d of desiccation corresponding to typical treatment times indicate tha t clinicians need to protect previously placed restorations from undue drying during subsequent dental treatment.