IADR Abstract Archives
Effect of high-intensity lights on the polymerization of bulk-fill composites
Objectives: To investigate the effect of high-irradiance light-curing-units (LCUs) on the depth-of-cure (DoC), degree-of-polymerization (DoP), and the photon-absorption efficacy of bulk-fill composites.
Methods: The DoC of various composite brands per LCU (n=3/group) were measured according to ISO-4049, using two high-irradiance LCUs (FlashMax-P3 [CMS-Dental] and SPEC3 [Coltene]) and a conventional LCU (Paradigm [3M-ESPE]) for exposure times: 3/9s, 3/20s, and 20s respectively. Using a Fourier transform infrared attenuated total reflection spectrometer, the DoP per composite brand were measured at the bottom surface (specimen thickness=4mm and Ø=10mm) as a function of post-curing times for Paradigm and FlashMax-P3 for exposure times of 10/20s and 3/9s respectively. Data collection for DoP began immediately after the completed aforesaid exposure times and continued at steady intervals for 7 minutes, then again after 24 hours. Finally, the absorbance (Absλ=469nm) per composite brand (n=2/group), having thickness=4mm and Ø=10mm per specimen, were measured as a function of curing times for Paradigm and FlashMax-P3 LCUs. Data were analyzed with nonlinear regression and ANOVA/Tukey (α=0.05).
Results: Significant differences (p<0.05) in DoC were found amongst FlashMax-P3, SPEC3, and Paradigm for various exposure times. However, no significant differences in Absλ=469nm for all composite brands were found between high-irradiance and conventional LCUs. In general, DoC and DoP improved with increasing exposure times while Absλ=469nm declined. Composite V exhibited the highest DoC and DoP than other 5 brands for any LCU-exposure time combination.
Conclusions: Bulk-fill composites cured with high-irradiance and short exposure time may not provide adequate DoC and DoP, which can lead to undesirable clinical properties. Irrespective of composite brands and LCUs, long exposure time always produced highest DoC and DoP. High DoC does not always associate with high DoP.
Methods: The DoC of various composite brands per LCU (n=3/group) were measured according to ISO-4049, using two high-irradiance LCUs (FlashMax-P3 [CMS-Dental] and SPEC3 [Coltene]) and a conventional LCU (Paradigm [3M-ESPE]) for exposure times: 3/9s, 3/20s, and 20s respectively. Using a Fourier transform infrared attenuated total reflection spectrometer, the DoP per composite brand were measured at the bottom surface (specimen thickness=4mm and Ø=10mm) as a function of post-curing times for Paradigm and FlashMax-P3 for exposure times of 10/20s and 3/9s respectively. Data collection for DoP began immediately after the completed aforesaid exposure times and continued at steady intervals for 7 minutes, then again after 24 hours. Finally, the absorbance (Absλ=469nm) per composite brand (n=2/group), having thickness=4mm and Ø=10mm per specimen, were measured as a function of curing times for Paradigm and FlashMax-P3 LCUs. Data were analyzed with nonlinear regression and ANOVA/Tukey (α=0.05).
Results: Significant differences (p<0.05) in DoC were found amongst FlashMax-P3, SPEC3, and Paradigm for various exposure times. However, no significant differences in Absλ=469nm for all composite brands were found between high-irradiance and conventional LCUs. In general, DoC and DoP improved with increasing exposure times while Absλ=469nm declined. Composite V exhibited the highest DoC and DoP than other 5 brands for any LCU-exposure time combination.
Conclusions: Bulk-fill composites cured with high-irradiance and short exposure time may not provide adequate DoC and DoP, which can lead to undesirable clinical properties. Irrespective of composite brands and LCUs, long exposure time always produced highest DoC and DoP. High DoC does not always associate with high DoP.
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