No abstract

Although some new-generation CAD/CAM and provisional restoration materials display slight cytotoxicity values, the results are still within the reliable range, and they can safely be used in clinical conditions.

The purpose of this study is to evaluate the effect of thermocycling on the color change of the amine-free dual-cure resin cements. IPS e.max CAD blocs were cut into specimens of 1 mm thickness (N=28) and cemented with one of the 4 different amine-free dual-cure resin cements (NX3 Nexus [NX], Kerr Dental; Variolink Esthetic DC [VE], Ivoclar Vivadent; Panavia V5 [PV], Kuraray Dental; G-CEM Linkforce [GC], GC Corporation) (n=7). A spectrophotometer was used for color measurements. Specimens were subjected to thermocycling (5°C and 55°C; 5000 and 10000 cycles). Normality of data distribution was tested by using the Kolmogorov-Smirnov test. Statistical analysis was performed using a two-way analysis of variance (ANOVA) and Tukey’s multiple comparison tests at a significance level of p<0.05. ∆E values were significantly influenced by the resin cements and the cycle periods (p<0.05). There were no significant differences between NX and VE groups after 5000 thermocycling, however after 10000 thermocycling VE group showed higher ∆E1 values than NX group (p>0.05).  There were no statistically significant differences between the ∆E0 and ∆E1 values of the GC group, however the other groups were affected after 10000 thermocycling (p>0.05). Amine-free resin cements used for cementation showed color change after thermocycling except GC group. All resin cements were showed clinically acceptable color change after thermocycling (∆E < 3.5).

SUMMARY Aim:The aim of this study was to evaluate the effect of different curing distances and ceramic materials on the microhardness of dual-cured resin cement. Materials and Methods:The dual-cured resin cement (NX3, Kerr) was polymerized between between lithium disilicate based pressed ceramic (IPS e.max Press (EP)), or three different CAD/CAM materials (Lava Ultimate (LU), e.max CAD (EC), Vita Suprinity (VS)) and a dentine surface with a LED light source from 0, 3 or 6 mm distances for 10 seconds (n=10). The Vickers microhardness (VH) values were recorded immediately after polymerization and after storage at dark in distilled water (24 h/37°C). Three indentations were made both on the top and the bottom surface of each specimen. ANOVA was used to analyse the data. Bonferroni test was used to perform multiple comparisons (p<0.05). Results: The resin cements under the LU specimens have significantly higher VH values compared to the other materials (p<0.05). The bottom surfaces have significantly lower hardness values for all ceramic materials (p<0.05). The VH value of 0 mm curing tip-ceramic distance was significantly higher than the groups of 3 and 6 mm distances (p<0.05). Microhardness values were significantly higher after 24 hours than immediate measurement (p<0.05). Conclusion: Ceramic material and the curing tip-ceramic distance are important factors to be considered for obtaining adequate polymerization.