The Influence of Resin Cement on Marginal Microleakage and Fracture Strength of CAD/CAM Generated Lithium Disilicate Crowns.
Abstract: Aim and hypothesis This study aimed to evaluate fracture strength and microleakage of CAD/CAM fabricated lithium disilicate crowns cemented with two resin cements. It was hypothesized that fracture strength of lithium disilicate crowns cemented with RelyX Ultimate is higher than those cemented with Variolink II. Additionally, it was hypothesized that marginal microleakage of lithium disi... read morelicate crowns cemented with RelyX Ultimate is higher than those cemented with Variolink II. Materials and method 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 Variolink II. For the 2A and 2B groups, the crowns were cemented with RelyX Ultimate. 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 (pvalue = 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). Conclusion 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 both cements was clinically acceptable.
Thesis (M.S.)--Tufts University, 2016.
Submitted to the Dept. of Other.
Advisor: Huda Stipho.
Committee: Ala Ali, Amit Sachdeo, and Matthew Finkelman.
Keyword: Dentistry.read less