Short-term and long-term release of monomers from newly developed resin-modified ceramics and composite resin CAD-CAM blocks.


Researcher, Department of Dental Tissues Pathology and Therapeutics, Division of Operative Dentistry, Faculty of Dentistry, Aristotle University of Thessaloniki, Thessaloniki, Greece. Electronic address: [Email]


BACKGROUND : Monomer leaching from restorations may affect the oral mucosa and general health; however, information on monomer leaching from chairside computer-aided design and computer-aided manufacturing (CAD-CAM) restorative materials is lacking.
OBJECTIVE : The purpose of this in vitro study was to investigate the leaching of monomers from newly introduced resin-modified ceramics and composite resin CAD-CAM blocks that were immersed in water and ethanol for short-term and long-term incubation periods.
METHODS : Ten square-shaped specimens of 5 newly introduced CAD-CAM blocks were suspended by means of a silk thread in distilled water and in 75% ethanol. After 1 day, 7 days, 30 days, and 60 days, the eluates bisphenol A (BPA), urethane dimethacrylate (UDMA), triethylene glycol dimethacrylate (TEGDMA), N, N-dimethylacrylamide (DMA), bisphenol A-glycidyl dimethacrylate (Bis-GMA), and bisphenol A ethoxylate dimethacrylate (Bis-EMA) were analyzed by means of high-performance liquid chromatography (HPLC). Additional specimens of each material, before and after immersion in the solutions, were investigated by scanning electron microscopy, and elemental analysis was performed by energy-dispersive X-ray spectrometry.
RESULTS : TEGDMA and UDMA were the main monomers eluted from all the materials tested. A pattern of declining release was detected for all the monomers. Bisphenol-A was not released by any of the investigated ceramic-composite or composite resin blocks either in water or ethanol.
CONCLUSIONS : CAD-CAM blocks release less monomer when they are immersed in aqueous solutions in the short-term and long-term periods than conventional resin composite materials. The amount of monomer release declined until no monomer could be detected.