After polymerization, no polishing techniques were used in order to avoid modification of the surfaces, which could influence the results.25 Colorimetric values of the composite resin specimens Olaparib PARP inhibitor before and after polymerization were measured using a spectrophotometer (Vita Easy-Shade, Vident, No: 502744, USA). The spectrophotometer comprises a base unit and a handpiece. In this system, the specimen was exposed to an emission of light, and the reflected light was analyzed with a spectrophotometer. Instrument calibration was evaluated after measurement of each group (n=10) and recalibration. The tip of the handpiece was placed firmly into the calibration port and was held steadily in place until the instrument sounded a beep to indicate that calibration was complete.
The measuring tip of the spectrophotometer was a circle 5 mm in diameter. Color measurement was performed in consecutive tests on central parts of the specimens. Specimens were positioned at the same place on different occasions to ensure consistency of the repeated measurements. A white plate was used for the background color in this study.22,26 All specimens were chromatically measured three times, and the average values were calculated. CIE L*a*b color system was used for determination of color difference. Changes in color coordinates (��L* ��a*and ��b*) were calculated as ��the value after polymerization �C the value before polymerization��. The formula of ��E*ab: ��E*?ab=[(��L*)2+(��a*)2+(��b*)2]1/2.Chroma?was?calculated?as?C*ab=(a*2+b*2)1/2. Statistical analysis The data were entered into a spreadsheet (Excel; version 4.
0, Microsoft, Seattle, WA, USA) for calculation of descriptive statistics. Analysis of variance (ANOVA) was used to analyze the data for significant differences. Tukey��s HSD test and paired two-tailed tests were used to perform multiple comparisons (��=.05). The data were analyzed with the SPSS 13 for Windows statistical program software (SPSS Inc., Chicago, IL, USA). RESULTS Colorimetric values of composite resin after polymerization are listed in Table 2. There were noticeable color changes in all groups (��E*ab 3.3). The range of changes in composite resin according to polymerization methods was 3.3�C4.6 in color (��E*ab: distribution span: 1.2), ?1.0 to ?1.6 in ��L* (distribution span: ?0.6), ?1.5 to ?2.8 in ��C*ab (distribution span: ?1.3), ?4.0 to ?2.
6 in ��a* (distribution span: ?1.4), ?1.7 to ?0.5 in ��b* (distribution span: ?1.2). There were no significant differences in color change among the groups (P>.05). Table 2 Changes in color and color parameters after polymerization. There were no Carfilzomib significant differences in CIE L* value (P>.05) among the groups. C*ab value was affected by polymerization methods (P<.05). There were significant differences between the inlay oven and the other four groups (P<.05).