IADR Abstract Archives
Resin Cement Color Stability After Accelerated Artificial Aging
Objectives: This investigation had two objectives:1- to evaluate the intrinsic color stability of four resin cements after water storage and exposure to an artificial sunlight source and 2- to evaluate the color changes of a ceramic restorative material following placement of the resin cements on the intaglio surface of the ceramic.
Methods: Cylindrical bulk cement specimens (n=8) of G-CEM one (G), Rely-X Universal (R), Panavia V5 (P) and Variolink Esthetic (V) were made measuring 8mm in diameter and 3mm in depth in a custom mold, visible light cured for 40 seconds and polished to a highly glossy surface using the Sof-lex system. Ceramic wafers measuring1 ± 0.1 mm were cut from GC Initial LiSi ceramic blocks and one side polished to a 4000 grit surface. After treating the non-polished surface the wafers were placed in a custom mold with a 0.12 mm thick chamber. Each cement was placed in the mold and the ceramic positioned over the cement and ight polymerized for 40 seconds.
After water storage for 24 hours at 37° C baseline color measurements were made with the Vita EasyShade instrument calculating Commission international de l’eclairage L*a*b* (CIELAB) values for each specimen. Each specimen was subjected to 16, four-hour aging cycles using a Xenon light source with an intensity of 0.4 W/m2. 8 specimens of each cement were used a control with no accelerated aging. Delta E was measured at baseline, after 7 days and after 28 days with the differences calculated from the CIELAB detla E values measured at baseline. Two-way ANOVA (cement and measurement period) and post-hoc LSD test was used for determining differences among the cements.
Results: The results for the bulk cement specimens are shown in Table 1 and for the ceramic specimens in Table 2. A change greater than 3 delta E units is considered to be the threshold of humans detecting color changes. All the P,G,and V all demonstrated changes from baseline below this level for the bulk and ceramic specimens. R generated higher delta E values than 3 for the bullk specimens and significantly greater color change compared to the other cements (p<0.05) for both bulk and ceramic groups.
Conclusions: There were significant differences in the measured delta E values for the cements exposed to accelerated aging based on the cement and measurement time.
Methods: Cylindrical bulk cement specimens (n=8) of G-CEM one (G), Rely-X Universal (R), Panavia V5 (P) and Variolink Esthetic (V) were made measuring 8mm in diameter and 3mm in depth in a custom mold, visible light cured for 40 seconds and polished to a highly glossy surface using the Sof-lex system. Ceramic wafers measuring1 ± 0.1 mm were cut from GC Initial LiSi ceramic blocks and one side polished to a 4000 grit surface. After treating the non-polished surface the wafers were placed in a custom mold with a 0.12 mm thick chamber. Each cement was placed in the mold and the ceramic positioned over the cement and ight polymerized for 40 seconds.
After water storage for 24 hours at 37° C baseline color measurements were made with the Vita EasyShade instrument calculating Commission international de l’eclairage L*a*b* (CIELAB) values for each specimen. Each specimen was subjected to 16, four-hour aging cycles using a Xenon light source with an intensity of 0.4 W/m2. 8 specimens of each cement were used a control with no accelerated aging. Delta E was measured at baseline, after 7 days and after 28 days with the differences calculated from the CIELAB detla E values measured at baseline. Two-way ANOVA (cement and measurement period) and post-hoc LSD test was used for determining differences among the cements.
Results: The results for the bulk cement specimens are shown in Table 1 and for the ceramic specimens in Table 2. A change greater than 3 delta E units is considered to be the threshold of humans detecting color changes. All the P,G,and V all demonstrated changes from baseline below this level for the bulk and ceramic specimens. R generated higher delta E values than 3 for the bullk specimens and significantly greater color change compared to the other cements (p<0.05) for both bulk and ceramic groups.
Conclusions: There were significant differences in the measured delta E values for the cements exposed to accelerated aging based on the cement and measurement time.