Context: The use of resin-based computer-aided design and computer-aided manufacturing (CAD/CAM) blocks is increasing in restorative dentistry. However, the potential elution of urethane dimethacrylate (UDMA) into saliva and its associated safety implications remain insufficiently investigated. Aims: To identify and quantify the monomer elution of two different indirect composite blocks before and after thermocycling. Settings and Design: In vitro study. Subjects and Methods: Two composite CAD-CAM blocks were investigated: a resin-based composite block (RCB, Shofu HC Block) and a polymer-infiltrated ceramic network block (PICN, Vita Enamic). Twenty specimens from each material ( n = 20) were prepared. All specimens ( n = 40) were immersed in artificial saliva at 37°C for 24 h before thermocycling. Extractions were performed after 24 h of immersion and subsequently after 500 and 10,000 cycles of thermocycling. UDMA monomer elution was analyzed using high performance liquid chromatography (HPLC). Statistical Analysis Used: Kruskal–Wallis test. Results: No quantifiable level of UDMA was observed in either RCB or PICN before thermocycling. After 500 cycles of thermocycling, UDMA elution was identified in RCB (0.04 mg/mL), but remained undetectable in PICN. Following 10,000 cycles of thermocycling, both RCB and PICN showed UDMA release of 0.01 mg/mL. However, the Kruskal–Wallis test revealed no statistically significant differences among groups ( P > 0.05). Conclusions: The highest UDMA elution occurred in RCB after 500 cycles of thermocycling. Despite differences in polymer structure, thermocycling did not significantly influence UDMA release in either material.
Hanifah et al. (2026) studied this question.