Influence of silanated filler content on the biodegradation of bisGMA/TEGDMA dental composite resins.

It has been shown that an increase in the content of nonsilanated submicron colloidal silica filler particles within dental composites resulted in the release of more bis-phenol-A diglycidyl dimethacrylate (bisGMA)-derived product, bis-hydroxy-propoxyphenyl propane, following incubation with cholesterol esterase (CE). This work further investigates the enzyme-catalyzed biodegradation of fine composite resin systems, containing silanated micron-size irregular glass fillers, commonly used in clinical restorations. Model composite resin samples (10 or 60% weight fraction silanated barium glass filler, 1 mum average particle size) based on bisGMA/triethylene glycol dimethacrylate (TEGDMA) were incubated in buffer or buffer with CE (pH = 7.0, 37 degrees C) solutions for 32 days. The incubation solutions were analyzed using high-performance liquid chromatography, UV spectroscopy, and mass spectrometry. Both groups were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. In contrast with previous findings for nonsilanated submicron filler systems, the higher filler containing composite showed an increase in its stability with time, following exposure to esterase and when compared to the lower filler content material. As well, the 60% filler composite leached less unreacted monomer TEGDMA. Since the model composite resins studied here were identical and only the filler content varied, the differences in biostability could be specifically associated with the relative amount of resin/filler distribution. The clinical use of different materials in varied dental applications (ranging from fissure sealant to tooth-colored highly filled materials) must consider the potential for different degradation profiles to occur as a function of filler content.