| Objectives: To measure retention of lithium disilicate (IPS e.max CAD, Ivoclar Vivadent) and zirconia reinforced lithium disilicate (CELTRA(TM) DUO, Dentsply) copings luted using resin cements and resin-modified glass ionomer cement.;Methods: 110 Extracted human, non-carious mandibular 2nd premolars (n=10) were embedded in PVC cylinders with acrylic resin and placed into a lathe to produce a uniform crown preparation (22°-convergence & 3mm-height). Following the orientation groove placement (69L bur), preparations were scanned and milled using a CEREC 3D/Sirona machine to produce e.max and CELTRA(TM) DUO crowns. Preparations were imaged with a digital microscope (Keyence/VHX-600-20X) and the surface area of each crown was calculated. IPS e.max crowns and CELTRA(TM) DUO crowns were cemented using the cements as in Tables 1 & 2. Specimens were stored (distilled water/37°C/24h) and thermocycled (10,000cycles/5-50°C/30secs) before debonding in tension at crosshead speed-5mm/min (INSTRON Model/5565). The bond strength was calculated by dividing the failure load with preparation surface area. The CELTRA(TM) DUO and e.max data were compared separately with 1-way ANOVA and Tukey post-hoc analysis (alpha= 0.05).;Results: The simulated crown strength test results for e.max were: Calibra=4.89+/-2.35a; ExpE(TE)=3.70+/-2.08a,b; ExpSE=3.18+/-2.03a,b RelyXLP=3.11+/-1.99a,b; ExpE(Self- Etch)=2.74+/-1.23a,b; Multilink=2.66+/-1.72a,b; RelyXU=2.65+/-1.46a,b; Reiv lyXLP/HF=1.91+/-0.70b. For CELTRA(TM): Exp/S=4.73+/-2.45a; Exp/S/E=4.40+/-1.76a,b; RelyXLP/ HF=3.34+/-1.65a,b, c; Exp=1.79+/-0.70b,c; and RelyXLP=0.95+/-0.58c. The ANOVA showed some significant differences between groups (p=0.01) where the same letter denotes similar groups.;Conclusions: The Calibra material resulted in significantly higher retention with the than RelyXLP/HF for the coping fabricated from e.max. The experimental resin cement with silane when compared to Exp and RelyXLP resulted in significantly higher test retention strength for the CELTRA(TM) DUO. |
