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Fast-fracture probability of implant-supported, three-unit, veneered zirconia, fixed dental prostheses
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d e n t a l m a t e r i a l s 2 9 S ( 2 0 1 3 ) e1–e96
The surgical sites were rinsed with 5% tranexamic acid solution in Groups II and IV. The animals were euthanized at 45 days postoperative. The pieces were processed in methyl methacrylate (Stevenel’s blue/Alizarin red). The percentage of peri-implant tissue repair was analyzed via images obtained by an optical microscope coupled to a digital camera using Leica software and Adobe Photoshop QWin. Data were analyzed statistically with a significance level of 5%. Results: Histomorphometric results showed 97.16% of bone-implant contact for group IV, 89.78% of bone contact for group III, 70.89% for group II and 61.59% of bone contact for group I. The statistical analyses demonstrated significant differences (P < 0.05) among group I and other groups. Conclusion: The results suggest that (a) Ti-30Ta promoted an increase of bone healing and apposition around implant; (b) tranexamic acid favored the stabilization of blood clot and bone formation.
Although the stress in the core can reach very high values, this ceramic has a very high reliability because of its high tensile strength. Because the consistently high probabilities of FDP fractures do not match clinical results, the sensitivity of model assumptions must be analyzed with a refined model to provide reliable predictions for the time-dependent probability of fracture. This study was supported by NIH/NIDCR grants DE06672 and K23DE18414. http://dx.doi.org/10.1016/j.dental.2013.08.004 4 Internal and marginal misfit of crowns produced with a new resin composite processed by CAD–CAM
http://dx.doi.org/10.1016/j.dental.2013.08.003
L.L. Arashiro ∗ , L.H. Silva, M.C.H.C.A. Villac¸a, E. Lima, P.F. Cesar
3
University of São Paulo, USP, Brazil
Fast-fracture probability of implant-supported, three-unit, veneered zirconia, fixed dental prostheses K.J. Anusavice 1,∗ , J. Esquivel-Upshaw 1 , R.B. Lee 1 , O.M. Jadaan 2 1 2
University of Florida, USA University of Mount Union, USA
Purpose: All-ceramic prostheses have virtually replaced metal-ceramic prostheses for replacement of missing teeth without sufficient evidence of reliability. These prostheses have been produced either from monolithic zirconia, veneered zirconia, or other ceramic–ceramic products. Objective: To analyze the effect of load orientation on the fracture probability of implant-supported, three-unit, zirconia/veneer prostheses. Methods and materials: A core ceramic (ZirCAD, Ivoclar Vivadent) and a veneering ceramic (ZirPress, Ivoclar Vivadent) were selected for bilayer models because of their use in an ongoing clinical study. The ANSYS finite element model design for the prosthesis, implants, and supporting bone consisted of 156,913 elements and 253,989 nodes. Finite element models were prepared for 2.0-mm-thick prostheses with a core/veneer thickness ratio of 0.5 mm/1.5 mm and 10 loading orientations. A 600-N load was applied at each of four locations for each case along a 1 mm2 area including the cusps of molar crowns. Results: A fracture probability of 100% was predicted for maximum principal failure stresses ( 1 ) in a cuspal area of the veneer ceramic ranging from 243 MPa (60◦ orientation relative to the horizontal axis) to 671 MPa (horizontal orientation). A loading angle of 75◦ will reduce 1 to 189 MPa and the veneer fracture probability to 49.2%. Conclusion: The stresses in the veneer for the applied load of 600 N over an area of 1 mm2 area are very high. Reliability analysis predicts a 100% failure probability in the fast fracture mode for all load locations and orientations except for those between 75◦ and 90◦ . All failures are likely to initiate in the veneer because of the low strength of the ceramic veneer.
Purpose: The objective of this study was to evaluate and compare the internal and marginal misfit of crowns machined by CAD–CAM of a new nanofilled resin composite reinforced with nano ceramic particles (LavaTM Ultimate – LU) with a lithium disilicate glass–ceramic (e.max CAD – EC). Methods and materials: Dentin analogous (G10) models were manufactured with a crown preparation and replicated in dental stone. These were digitized by the CAD–CAM for virtual 3D modeling of the crowns for the two materials (n = 5). After machining, the crowns were placed in their respectively G10 models interposed by a light body addition silicone layer, copying the cementation space. The polymerized light body silicone film was captured with a silicon putty to obtain 4 slices corresponding to the crown faces: buccal, mesial, lingual and distal. The misfit was measured at five points: pulp, axial-pulp angle, axial, axial-gingival angle and marginal. The data were submitted to 3-way ANOVA (2 factors within groups) and Tukey’s test (a = 0.05). Results: LU (198.1 ± 102.6 m) showed a lower misfit (p = 0.042) than the EC (287.2 ± 102.6 m). The lowest misfit was observed in the axial point for both materials (p = 0.000). No difference was observed (p = 0.201) among the crowns faces. LU showed lower misfit (p = 0.001) in pulp point (LU: 318.8 ± 82.6 m/EC: 450.2 ± 104.3 m) and marginal point (LU: 221.5 ± 67.1 m/EC: 321.8 ± 136.4 m) than the glass–ceramic. Conclusion: Crowns milled from the new resin composite had a better fit than the glass–ceramic ones, indicating that there is an important difference between the machining ability of these materials. http://dx.doi.org/10.1016/j.dental.2013.08.005
d e n t a l m a t e r i a l s 2 9 S ( 2 0 1 3 ) e1–e96
The surgical sites were rinsed with 5% tranexamic acid solution in Groups II and IV. The animals were euthanized at 45 days postoperative. The pieces were processed in methyl methacrylate (Stevenel’s blue/Alizarin red). The percentage of peri-implant tissue repair was analyzed via images obtained by an optical microscope coupled to a digital camera using Leica software and Adobe Photoshop QWin. Data were analyzed statistically with a significance level of 5%. Results: Histomorphometric results showed 97.16% of bone-implant contact for group IV, 89.78% of bone contact for group III, 70.89% for group II and 61.59% of bone contact for group I. The statistical analyses demonstrated significant differences (P < 0.05) among group I and other groups. Conclusion: The results suggest that (a) Ti-30Ta promoted an increase of bone healing and apposition around implant; (b) tranexamic acid favored the stabilization of blood clot and bone formation.
Although the stress in the core can reach very high values, this ceramic has a very high reliability because of its high tensile strength. Because the consistently high probabilities of FDP fractures do not match clinical results, the sensitivity of model assumptions must be analyzed with a refined model to provide reliable predictions for the time-dependent probability of fracture. This study was supported by NIH/NIDCR grants DE06672 and K23DE18414. http://dx.doi.org/10.1016/j.dental.2013.08.004 4 Internal and marginal misfit of crowns produced with a new resin composite processed by CAD–CAM
http://dx.doi.org/10.1016/j.dental.2013.08.003
L.L. Arashiro ∗ , L.H. Silva, M.C.H.C.A. Villac¸a, E. Lima, P.F. Cesar
3
University of São Paulo, USP, Brazil
Fast-fracture probability of implant-supported, three-unit, veneered zirconia, fixed dental prostheses K.J. Anusavice 1,∗ , J. Esquivel-Upshaw 1 , R.B. Lee 1 , O.M. Jadaan 2 1 2
University of Florida, USA University of Mount Union, USA
Purpose: All-ceramic prostheses have virtually replaced metal-ceramic prostheses for replacement of missing teeth without sufficient evidence of reliability. These prostheses have been produced either from monolithic zirconia, veneered zirconia, or other ceramic–ceramic products. Objective: To analyze the effect of load orientation on the fracture probability of implant-supported, three-unit, zirconia/veneer prostheses. Methods and materials: A core ceramic (ZirCAD, Ivoclar Vivadent) and a veneering ceramic (ZirPress, Ivoclar Vivadent) were selected for bilayer models because of their use in an ongoing clinical study. The ANSYS finite element model design for the prosthesis, implants, and supporting bone consisted of 156,913 elements and 253,989 nodes. Finite element models were prepared for 2.0-mm-thick prostheses with a core/veneer thickness ratio of 0.5 mm/1.5 mm and 10 loading orientations. A 600-N load was applied at each of four locations for each case along a 1 mm2 area including the cusps of molar crowns. Results: A fracture probability of 100% was predicted for maximum principal failure stresses ( 1 ) in a cuspal area of the veneer ceramic ranging from 243 MPa (60◦ orientation relative to the horizontal axis) to 671 MPa (horizontal orientation). A loading angle of 75◦ will reduce 1 to 189 MPa and the veneer fracture probability to 49.2%. Conclusion: The stresses in the veneer for the applied load of 600 N over an area of 1 mm2 area are very high. Reliability analysis predicts a 100% failure probability in the fast fracture mode for all load locations and orientations except for those between 75◦ and 90◦ . All failures are likely to initiate in the veneer because of the low strength of the ceramic veneer.
Purpose: The objective of this study was to evaluate and compare the internal and marginal misfit of crowns machined by CAD–CAM of a new nanofilled resin composite reinforced with nano ceramic particles (LavaTM Ultimate – LU) with a lithium disilicate glass–ceramic (e.max CAD – EC). Methods and materials: Dentin analogous (G10) models were manufactured with a crown preparation and replicated in dental stone. These were digitized by the CAD–CAM for virtual 3D modeling of the crowns for the two materials (n = 5). After machining, the crowns were placed in their respectively G10 models interposed by a light body addition silicone layer, copying the cementation space. The polymerized light body silicone film was captured with a silicon putty to obtain 4 slices corresponding to the crown faces: buccal, mesial, lingual and distal. The misfit was measured at five points: pulp, axial-pulp angle, axial, axial-gingival angle and marginal. The data were submitted to 3-way ANOVA (2 factors within groups) and Tukey’s test (a = 0.05). Results: LU (198.1 ± 102.6 m) showed a lower misfit (p = 0.042) than the EC (287.2 ± 102.6 m). The lowest misfit was observed in the axial point for both materials (p = 0.000). No difference was observed (p = 0.201) among the crowns faces. LU showed lower misfit (p = 0.001) in pulp point (LU: 318.8 ± 82.6 m/EC: 450.2 ± 104.3 m) and marginal point (LU: 221.5 ± 67.1 m/EC: 321.8 ± 136.4 m) than the glass–ceramic. Conclusion: Crowns milled from the new resin composite had a better fit than the glass–ceramic ones, indicating that there is an important difference between the machining ability of these materials. http://dx.doi.org/10.1016/j.dental.2013.08.005