Effect of storage conditions on mechanical properties of resin composite blanks for CAD/CAM crowns.

The objective of this study was to examine the effects of storage conditions on the flexural strengths of resin composite materials for CAD/CAM restorations. Seven commercially available resin composite CAD/CAM blanks were examined. Rectangular specimens (4.0×1.2×4.0 mm) of each material were trimmed from the blanks and subjected to thermal cycling between 5°C and 55°C in deionized water at 10,000 cycles or stored in 37°C deionized water for one week or air for one day (n=10 for each condition). The difference in storage condition between water immersion and thermal cycling did not affect the flexural strengths of resin composite materials for CAD/CAM examined in this study. The resin composite block CS300 made from Bis-MEPP and UDMA showed the greatest flexural strength under all storage conditions and less deterioration of strength by thermal cycling and water immersion among the resin composite blocks tested.