Microleakage of Lithium Disilicate Ceramic Crowns vs. Nano Ceramic Crowns

Objectives: To evaluate and compare the microleakage of lithium disilicate ceramics (IPS e.max, IvoclarVivadent AG, Liechtenstein) and CAD/CAM crowns made of nano ceramics (CERASMART, GC, Tokyo, Japan) on extracted teeth after thermocycling testing. It was hypothesized that lithium disilicate crowns would have lower microleakage values compared to nano ceramic ones.
Methods: Thirty extracted human third molar teeth were prepared in a consistent way to receive full-coverage CAD/CAM crowns. The specimens were scanned and designed using the CEREC system. The crowns were fabricated from IPS e.max CAD blocks and CERASMART CAD/CAM blocks using a CEREC milling machine. The specimens were randomly distributed into two groups. The crowns of both groups were attached using Rely X Ultimate resin cement. All crowns were subjected to 10,000 thermocycles and then immersed in silver nitrate followed by using a photo-developer. Specimens were segmented buccolingually and the microleakage was measured at 1.0 magnification using a stereomicroscope. Descriptive statistics were computed. For the percentage microleakage scale, the Mann-Whitney U test was used since the data were not normally distributed. For the ordinal microleakage scale, statistical significance between groups was judged by generalized estimating equations (GEE). SPSS version 22 and SAS 9.4 were used in the analysis and p-values of less than 0.05 were considered statistically significant.
Results: The CERASMART group showed lower median microleakage at 5.9% (IQR=20.7) than the e.max group, which showed a median microleakage of 7.4% (IQR=13.9). No statistically significant difference between the groups was found (p = 0.806). For the ordinal data, there was no statistically significant difference between the groups (p = 0.605).
Conclusions: Within the limitations of this study, no proven evidence showed a statistically significant difference when comparing the microleakage of lithium disilicate crowns and nano ceramic crowns.