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Rugosimetric analysis of a microhybrid composite polished with four protocols
d e n t a l m a t e r i a l s 2 6 S ( 2 0 1 0 ) e1–e84
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12-h Post-polymerization of a nanohybrid resin composite: Conversion degree’s evaluation
Rugosimetric analysis of a microhybrid composite polished with four protocols
N. Scotti 1 , A. Venturello 2 , F. Pera 1 , D. Pasqualini 1 , E. Berutti 1
D. Angerame, D. Sossi, M. Cattaruzza, F. Spizzo, M. De Biasi
1
University of Trieste, Trieste, Italy
2
University of Turin, Italy Polytechnical School of Turin, Italy
Objectives: The aim of this in vitro study was to evaluate the conversion degree progression, during the post-photopolymerization, of a nanohybrid resin composite irradiated with a LED lamp (Trouffier-Boutry et al., J Dent Res; 2006). Materials and methods: A commercially available nanohybrid resin composite (Venus Diamond, Heraeus Kultzer, Hanau, Germany) was selected for this study. The resin composite was bulk placed inside aluminum rings, 10 mm diameter, with different thickness (1 mm, 2 mm). A total of 32 samples were prepared and divided in 2 groups of sixteen samples each. The curing device employed in this study was a LED light (Translux Power Blue, Haereus Kultzer, Hanau, Germany). Each group was divided in 2 subgroups on the basis of the irradiation time (10 s, 40 s). The degree of conversion at the bottom surface of each sample was accomplished by Attenuated Total Reflection Fourier Transform Infrared (ATR F-TIR) analysis (Eqinox 55, Bruker Optics S.p.A.) immediately after photopolymerization and every 10 min for 12 h. In this study the conversion degree obtained immediately (T = 0), after 30 min (T = 1) and after 12 h (T = 2) from the photo-polymerization was considered. Differences among groups were analyzed with the non-parametric Mann–Whitney U-test (p < 0.05). Results:
10 s 40 s 10 s 40 s
1 mm 1 mm 2 mm 2 mm
T=0
T=1
T=2
31.8% 24.1% 40.5% 38.6%
44.6% 35.9% 47.8% 45.3%
52.4% 43.1% 54.2% 52.3%
Conclusions: Within 1 mm specimens, 10 s curing time produced in T = 0 and T = 1 a conversion degree significantly lower than the conversion degree obtained with a curing time of 40 s (p < 0.05); however, during the post-polymerization process, the mean conversion degree values got closer being not statistically different after 12 h (p = 0.09). On the contrary, 2 mm samples did not achieve a satisfactory conversion degree after 10 s curing, which is significantly lower than 40 s curing time (p < 0.05). Even during post-polymerization the conversion degree did not significantly increase, concluding that 2 mm composite stratification needs 40 s curing time to achieve a sufficient conversion degree. doi:10.1016/j.dental.2010.08.091
Objectives: Composite restorations with complex anatomy are difficult to polish; rigidity of rubber points can alter surface texture. The purpose of this study was to investigate the surface roughness of a microhybrid composite polished with abrasive pastes or rubber points, with or without superficial light-cured resin. Materials and methods: Forty discs (diameter 7 mm × 1.5 mm) of composite (Filtek Z250, 3M ESPE) were light cured and randomly divided into four groups (n = 10): group 1 (G1), rubber points (70, 40, and 5 m, Identoflex AG); group 2 (G2), abrasive pastes (80, 35, and 4 m, FGM); group 3 (G3), rubber points (=G1) and Seal Coat Fast resin (DEI Italia); group 4 (G4), abrasive pastes (=G2) and Seal Coat Fast resin. The specimens were analyzed using a rugosimeter (Talysurf CLI 1000, Taylor Hobson) considering a linear parameter (Ra ); nine standardized 0.5 mm long measurements were made for each specimen. A 0.2 m roughness value was assumed as clinically acceptable threshold. Collected data were statistically analyzed with Kruskal–Wallis and Mann–Whitney tests (p < 0.05). Samples were then observed with SEM, running in low vacuum mode, without any sample preparation and by means of backscattered electron detector. Results: Roughness values were lower than 0.2 m in all groups. Mean Ra values ± SD (m) were: G1 = 0.07 ± 0.02, G2 = 0.06 ± 0.01; G3 = 0.06 ± 0.04; G4 = 0.03 ± 0.01. Significant differences among groups were found: G1 vs. G2 (p < 0.05); G1, G2 and G3 vs. G4 (p < 0.01). Grooves and loss of superficial filler were found in G1 and G2; grooves in G1 were parallel. Specimens treated with surface resin coat presented smoother aspect than untreated specimens. Conclusions: All tested techniques offered roughness values under clinically acceptable threshold on flat surfaces. Abrasive pastes seem to be a valid alternative to rubber points when used on restoration with complex anatomy. Best results were obtained in G4; resin coating improves surface smoothness obtained with pastes. doi:10.1016/j.dental.2010.08.092 85 Nanogel-modified composite materials: Route to low shrinkage and stress J.W. Stansbury, R.R. Moraes, J.W. Garcia, M.D. Barros, S.H. Lewis, C.S. Pfeifer University of Colorado, Aurora, USA Objectives: The use of reactive pre-polymerized, nanosized particles to reduce reactive group concentration (and, as a consequence, shrinkage and stress) is proposed here. As opposed to ground, micro-sized, cured composite particles previously used as additives, nanogels allow for a higher amount of prepolymer to be added, without interfering with inorganic filler
e39
83
84
12-h Post-polymerization of a nanohybrid resin composite: Conversion degree’s evaluation
Rugosimetric analysis of a microhybrid composite polished with four protocols
N. Scotti 1 , A. Venturello 2 , F. Pera 1 , D. Pasqualini 1 , E. Berutti 1
D. Angerame, D. Sossi, M. Cattaruzza, F. Spizzo, M. De Biasi
1
University of Trieste, Trieste, Italy
2
University of Turin, Italy Polytechnical School of Turin, Italy
Objectives: The aim of this in vitro study was to evaluate the conversion degree progression, during the post-photopolymerization, of a nanohybrid resin composite irradiated with a LED lamp (Trouffier-Boutry et al., J Dent Res; 2006). Materials and methods: A commercially available nanohybrid resin composite (Venus Diamond, Heraeus Kultzer, Hanau, Germany) was selected for this study. The resin composite was bulk placed inside aluminum rings, 10 mm diameter, with different thickness (1 mm, 2 mm). A total of 32 samples were prepared and divided in 2 groups of sixteen samples each. The curing device employed in this study was a LED light (Translux Power Blue, Haereus Kultzer, Hanau, Germany). Each group was divided in 2 subgroups on the basis of the irradiation time (10 s, 40 s). The degree of conversion at the bottom surface of each sample was accomplished by Attenuated Total Reflection Fourier Transform Infrared (ATR F-TIR) analysis (Eqinox 55, Bruker Optics S.p.A.) immediately after photopolymerization and every 10 min for 12 h. In this study the conversion degree obtained immediately (T = 0), after 30 min (T = 1) and after 12 h (T = 2) from the photo-polymerization was considered. Differences among groups were analyzed with the non-parametric Mann–Whitney U-test (p < 0.05). Results:
10 s 40 s 10 s 40 s
1 mm 1 mm 2 mm 2 mm
T=0
T=1
T=2
31.8% 24.1% 40.5% 38.6%
44.6% 35.9% 47.8% 45.3%
52.4% 43.1% 54.2% 52.3%
Conclusions: Within 1 mm specimens, 10 s curing time produced in T = 0 and T = 1 a conversion degree significantly lower than the conversion degree obtained with a curing time of 40 s (p < 0.05); however, during the post-polymerization process, the mean conversion degree values got closer being not statistically different after 12 h (p = 0.09). On the contrary, 2 mm samples did not achieve a satisfactory conversion degree after 10 s curing, which is significantly lower than 40 s curing time (p < 0.05). Even during post-polymerization the conversion degree did not significantly increase, concluding that 2 mm composite stratification needs 40 s curing time to achieve a sufficient conversion degree. doi:10.1016/j.dental.2010.08.091
Objectives: Composite restorations with complex anatomy are difficult to polish; rigidity of rubber points can alter surface texture. The purpose of this study was to investigate the surface roughness of a microhybrid composite polished with abrasive pastes or rubber points, with or without superficial light-cured resin. Materials and methods: Forty discs (diameter 7 mm × 1.5 mm) of composite (Filtek Z250, 3M ESPE) were light cured and randomly divided into four groups (n = 10): group 1 (G1), rubber points (70, 40, and 5 m, Identoflex AG); group 2 (G2), abrasive pastes (80, 35, and 4 m, FGM); group 3 (G3), rubber points (=G1) and Seal Coat Fast resin (DEI Italia); group 4 (G4), abrasive pastes (=G2) and Seal Coat Fast resin. The specimens were analyzed using a rugosimeter (Talysurf CLI 1000, Taylor Hobson) considering a linear parameter (Ra ); nine standardized 0.5 mm long measurements were made for each specimen. A 0.2 m roughness value was assumed as clinically acceptable threshold. Collected data were statistically analyzed with Kruskal–Wallis and Mann–Whitney tests (p < 0.05). Samples were then observed with SEM, running in low vacuum mode, without any sample preparation and by means of backscattered electron detector. Results: Roughness values were lower than 0.2 m in all groups. Mean Ra values ± SD (m) were: G1 = 0.07 ± 0.02, G2 = 0.06 ± 0.01; G3 = 0.06 ± 0.04; G4 = 0.03 ± 0.01. Significant differences among groups were found: G1 vs. G2 (p < 0.05); G1, G2 and G3 vs. G4 (p < 0.01). Grooves and loss of superficial filler were found in G1 and G2; grooves in G1 were parallel. Specimens treated with surface resin coat presented smoother aspect than untreated specimens. Conclusions: All tested techniques offered roughness values under clinically acceptable threshold on flat surfaces. Abrasive pastes seem to be a valid alternative to rubber points when used on restoration with complex anatomy. Best results were obtained in G4; resin coating improves surface smoothness obtained with pastes. doi:10.1016/j.dental.2010.08.092 85 Nanogel-modified composite materials: Route to low shrinkage and stress J.W. Stansbury, R.R. Moraes, J.W. Garcia, M.D. Barros, S.H. Lewis, C.S. Pfeifer University of Colorado, Aurora, USA Objectives: The use of reactive pre-polymerized, nanosized particles to reduce reactive group concentration (and, as a consequence, shrinkage and stress) is proposed here. As opposed to ground, micro-sized, cured composite particles previously used as additives, nanogels allow for a higher amount of prepolymer to be added, without interfering with inorganic filler