IADR Abstract Archives
One-Shade Versus Multi-Shade Composites: Effects of Cholesterol Esterase Biodegradation
Objectives: The susceptibility of composites organic matrix to degradation by salivary and bacterial esterases has been well documented. Our lab has previously shown that the optical behavior of a one-shade composite is more stable than a multi-shade composite. We investigated the effects of cholesterol esterase (CE) biodegradation on two one-shade composites (Omnichroma (OM), Tokuyama and Venus Pearl ONE (VP), Kulzer) and one multi-shade composite (Tetric EvoCeram (TE), Ivoclar-Vivadent).
Methods: Composite discs (n=5/group) were prepared using custom molds (15mm x 2mm) and photopolymerized for 40s (20s/side) using an LED-unit (VALO, Ultradent; irradiance>1.2W/cm2). Color coordinates (L,a*,b*) were quantified using a colorimeter (spectro2go, BYK) against white and black backgrounds. Discs were incubated at 37°C in 2mL PBS added, or not, with CE from pseudomonas sp. (20 units/mL) for 9 days. Specimens were rinsed and let dried. Color measurements were taken again. CIELAB formulae were used to calculate color differences (ΔE) and translucency parameter (TP). Bar-like composites (24mm x 2mm x 1mm) were prepared (n=10/group) and submitted to the same incubation regimen (PBS or PBS+CE, 9 days, 37°C) for assessment of the effects of CE-biodegradation on composites flexural strength (FS) and modulus of elasticity (E). Optical (ΔE, TP) and mechanical properties (FS and E) were analyzed by ANOVA and Tukey post hoc tests (a=0.05).
Results: CE-incubation had no significant effect on composites ΔE. OM showed the greatest TP followed by TE and VP both at baseline and after 9-day CE-incubation. Conversely, VP showed significantly higher FS and E in comparison to OM and TE with VP>OM; VP>TE; OM=TE at baseline and after 9-day CE-incubation. CE-incubation significantly reduced the FS and E of composites in 20% for OM and TE and 23% for VP.
Conclusions: Short-term incubation in CE did not affect composites optical properties but had a detrimental effect on their mechanical properties.
Methods: Composite discs (n=5/group) were prepared using custom molds (15mm x 2mm) and photopolymerized for 40s (20s/side) using an LED-unit (VALO, Ultradent; irradiance>1.2W/cm2). Color coordinates (L,a*,b*) were quantified using a colorimeter (spectro2go, BYK) against white and black backgrounds. Discs were incubated at 37°C in 2mL PBS added, or not, with CE from pseudomonas sp. (20 units/mL) for 9 days. Specimens were rinsed and let dried. Color measurements were taken again. CIELAB formulae were used to calculate color differences (ΔE) and translucency parameter (TP). Bar-like composites (24mm x 2mm x 1mm) were prepared (n=10/group) and submitted to the same incubation regimen (PBS or PBS+CE, 9 days, 37°C) for assessment of the effects of CE-biodegradation on composites flexural strength (FS) and modulus of elasticity (E). Optical (ΔE, TP) and mechanical properties (FS and E) were analyzed by ANOVA and Tukey post hoc tests (a=0.05).
Results: CE-incubation had no significant effect on composites ΔE. OM showed the greatest TP followed by TE and VP both at baseline and after 9-day CE-incubation. Conversely, VP showed significantly higher FS and E in comparison to OM and TE with VP>OM; VP>TE; OM=TE at baseline and after 9-day CE-incubation. CE-incubation significantly reduced the FS and E of composites in 20% for OM and TE and 23% for VP.
Conclusions: Short-term incubation in CE did not affect composites optical properties but had a detrimental effect on their mechanical properties.