Title: 1577 - Marginal Microleakage and Fracture Strength of CAD/CAM Lithium Disilicate Crowns
Ahmed Alhwaj (Presenter)
Tufts University School of Dental Medicine
Huda Stipho, Tufts University School of Dental Medicine
Amit Sachdeo, Tufts University School of Dental Medicine
Matthew Finkelman, Tufts University School of Dental Medicine
ALA ALI, Tufts University School of Dental Medicine
Objectives: The objective of this in vitro study was to evaluate fracture strength and microleakage of CAD/CAM fabricated lithium disilicate posterior crowns cemented with RelyX™ Ultimate (R) and Variolink®II (V) resin cements.
Methods: Fifty four extracted human molars were prepared in a standardized manner for full crown coverage. The samples were scanned and designed using E4D system. The crowns were milled out of IPS e.max CAD blocks using E4D milling center. The samples were randomly divided into four groups; 1A, 1B, 2A and 2B. For both the 1A and 1B groups, the crowns were cemented with V. For the 2A and 2B groups, the crowns were cemented with R. All groups were subjected to 5,000 thermocycles. Then, groups 1A and 2A were loaded until catastrophic fracture occurred. Groups 1B and 2B were immersed in silver nitrate dye then sectioned buccolingually and the microleakage were measured under a stereomicroscope at 1.25 magnification.
Results: For fracture strength, the mean for group 1A was 2434.6 N (SD = 531.8), and for group 2A, the mean was 2453.1 N (SD = 471 N). The difference was not statistically significant (p-value = 0.937). For microleakage, the median for group 1B was 11.4% (IQR = 6.3%) and for group 2B, the median was 9% (IQR = 8.7%). The difference was not statistically significant (p-value = 0.438).
Conclusions: There was no evidence that the choice between RelyX Ultimate and Variolink II influences the microleakage and fracture strength of CAD/CAM fabricated lithium disilicate crowns. In addition, the lithium disilicate crowns’ fracture strength, using any of the two cements, was clinically acceptable.
The submitter must disclose the names of the organizations with which any author have a relationship, the nature of the relationship, and the clinical or research area involved. The following is submitted: NONE