Paper: Dental Nanocomposites: Mechanical Properties in Long-Term Water-Aging (IADR/AADR/CADR 87th General Session and Exhibition (April 1-4, 2009))

588 Dental Nanocomposites: Mechanical Properties in Long-Term Water-Aging

Thursday, April 2, 2009: 2 p.m. - 3:15 p.m.
Location: Exhibit Hall D (Miami Beach Convention Center)
E. LEVINE1, H.H.K. XU1, J.L. MOREAU1, and H. STRASSLER2, 1University of Maryland Dental School, Baltimore, MD, 2University of Maryland, Baltimore, MD
Several composites have recently been commercially available as nanocomposites for tooth restorations. Other nano-hybrid composites are also available. However, little is known about the long-term properties and performance of these nanocomposites. OBJECTIVES: To investigate the new generation of nanocomposites and nano-hybrid composites, to correlate the properties with composite microstructure, and to provide clinician with information on different nanocomposites. METHODS: Five commercial nanocomposites and four nano-hybrid composites were studied. Flexural strength and elastic modulus were measured vs. water-immersion time for specimens without immersion, and with immersion for 1 day, 1 month, 3 months, 6 months, 9 months, and 1 year. RESULTS: Significant differences were found between different composites under the same treatment, and for the same composite after different immersion time (p < 0.05). In general, nano-hybrid composites had higher strengths than nanocomposites. For example, Grandio (Voco, Cuxhaven, Germany), a nano-hybrid, had a flexural strength (mean sd; n = 6) of (130 9) MPa after 1 month of immersion, significantly higher than (79 9) MPa of a nanocomposite (Artiste, Pentron) and (94 11) MPa of another nanocomposite (Premise, Kerr, Orange, CA) (p < 0.05). Grandio's elastic modulus of (18.0 0.8) GPa was also higher than those of the nanocomposites, which ranged from 7 to 10 GPa (p < 0.05). CONCLUSION: Hybrid composites generally had higher strength and elastic modulus than nanocomposites in water-aging. However, nanocomposites were stronger than previously-reported microfill composites. It is important to note that while some nanocomposites may have lower strength than some hybrid composites, nanocomposites may have other meritorious features such as higher esthetics and gloss retention, topics that require further study. Partially supported by NIH R01 DE14190 and DE17974 (to HX).