thickness) were manufactured by CAD/CAM (CEREC InLab. MC XL, Sirona Dental Systems) and divided into 8 groups according to the processing techniques ...
e14
d e n t a l m a t e r i a l s 2 9 S ( 2 0 1 3 ) e1–e96
universal testing machine with a speed of 0.5 mm/min and the values of flexural strength were analyzed statistically by ANOVA two-way test. Results: The flexural strength was higher for CAD group (p-value = 0.011). HF group showed lower flexural strength if compared with HFL (p-value = 0.03). The interaction between factors was insignificant (p-value = 0.328). Conclusion: The processing method influenced the flexural strength of lithium disilicate ceramic. The lost wax technique ceramic bars showed worse flexural strength. The application of etching agent only could decrease the mechanical strength. http://dx.doi.org/10.1016/j.dental.2013.08.030 30 Effect of different particle deposition protocols on the wettability of zirconia F. Leite 1,∗ , V.E.S.M. Paschoalino 1 , B.J. Paschoalino 1 , E.A. Rocha 1 , Y.A. Mota 1 , M. Ozcan 2 1
Federal University of Juiz De Fora, Juiz De Fora, Brazil 2 University of Zurich, Zurich, Switzerland Purpose: The aim of this study was to evaluate the influence of air-abrasion protocols on the surface morphology and wettability of zirconia. Methods and materials: Zirconia disk specimens (N = 36) (15 mm × 2 mm) (LAVA) were polished and randomly divided into the following groups: ST-untreated; A80-air-abrasion (Al2 O3 80 m); A45-air-abrasion (Al2 O3 45 m); R110air-abrasion (Al2 O3 coated SiO2 110 m) (Rocatec Plus): R30-air-abrasion (Al2 O3 coated SiO2 30 m; Rocatec Soft), R110R30 − R110 + R30, C30-air-abrasion (Al2 O3 coated SiO2 30 m; CoJet). Air-abrasion was performed in a standardized manner at constant pressure of 2.5 bar, from a distance of 10 mm, in circular motion for 90 s. The surfaces of the specimens were analyzed in Scanning Electron Microscope (2000×). The contact angle was measured by goniometry. Results: Data were analyzed using one-way ANOVA and Tukey’s (a = 0.05). Air-abrasion protocols affected the contact angle values significantly. ST(116 ± 1)A demonstrated higher contact angle followed by groups R110(80.7 ± 0.8)B, A80(78.4 ± 0.6)B, A45(63.5 ± 0.9)C, C30(62.7 ± 0.9)CD, R30(61.9 ± 2)D and R110R30(61.5 ± 1)D. Conclusion: The photomicrographs illustrated more homogeneous surfaces for groups where contact angle was low. Particle deposition using smaller particles provided more homogeneous surfaces with which increased wettability was obtained. http://dx.doi.org/10.1016/j.dental.2013.08.031
31 Crowns’ fracture resistance: Effects of thicknesses, processing techniques and cooling protocols J.M.C. Lima 1,∗ , L.C. Anami 1 , S.M.B. Pereira 1 , F. Campos 1 , A.K.F. Costa 1 , R.M. Melo 1 , R.O.A. Souza 2 , M.A. Bottino 1 1 2
UNESP – Univ Estadual Paulista, Brazil Federal University of Paraiba, Brazil
Purpose: The aim of this study was to evaluate, in vitro, the influence of cooling protocols, processing techniques and of the thickness of veneering ceramics on the fracture resistance of crowns made with zirconia infrastructures. Methods and materials: 80 identical zirconia (Vita InCeram YZ, Vita Zahnfabrik) molar frameworks (1.0 mm thickness) were manufactured by CAD/CAM (CEREC InLab MC XL, Sirona Dental Systems) and divided into 8 groups according to the processing techniques (stratified, Vita VM9, Vita Zahnfabrik – V or pressed Vita PM9, Vita Zahnfabrik – P), the thickness (1 or 2 mm) and the cooling protocol (slow – S or fast – F) of the veneering ceramic. All crowns were cemented onto G10 abutments using resin cement (Panavia F 2.0, Kuraray). The crowns were also mechanically cycled (Fmax = 200 N; 2,000,000 cycles; 3 Hz) and after the cycling the presence of chipping and delamination was observed under stereomicroscopy. The fracture test was performed (0.5 mm/min, 1000 kgf), the failure mode was classified and the failure origin was determined as well. The data (in kgf) were statistically analyzed using 3-way ANOVA and Tukey’s tests (5%). Results: There was an influence of the cooling protocol (p = 0.0058) and the application technique (p = 0.0001) on the results of the stratified and pressed techniques. The slow cooling differed from the fast cooling in the pressed ceramic crown with 2.0 mm, however, this difference was not observed in the stratified crowns, regardless the thickness of the veneering ceramic. The predominant type of failure was chipping (52.5%) of the veneering ceramic and type II (33.75%) according to Burke’s classification. In both stratified and pressed techniques the failure origin was found on the subsurface. Conclusion: In slow cooling, crowns made by the pressed technique have greater resistance to fracture than those made by the stratified technique, no matter the thickness. Cooling protocol
Thickness (mm)
Slow
1 2 1 2
Processing techniques Pressed
Fast
418.4 470.3 402.2 369.5
± ± ± ±
66.8AB 47.4A 55.0ABC 53.37BCD
Stratified 309.0 329.8 300.3 314.2
Different letters indicate a statistical difference (p < 0.05).
http://dx.doi.org/10.1016/j.dental.2013.08.032
± ± ± ±
77.8D 40.3CD 42.5D 51.1D
