All-ceramic Core Research Articles

Effect of Two Connector Designs on the Fracture Resistance of All-Ceramic Core Materials for Fixed Dental Prostheses: An In-Vitro Study

Background: The aim of this study was to test the difference in fracture resistance of 3 ceramic core materials used for simulated 3-unit all-ceramic FPDs with 2 fabrication techniques (lost-wax/heat-pressing and CAD/CAM methods) and 2 connector designs (round and sharp). Material and method: The present in vitro study was conducted in the Department of Prosthodontics and Crown & Bridge, Subharti Dental College & Hospital, Meerut, Uttar Pradesh. For the purpose of this study, 3 all ceramic core materials were selected viz. Yittrium-tetragonal zirconia polycrystals, Milled Lithium disilicate glass ceramic and Lost-wax/heat-pressed lithium disilicate glass ceramic. A total of 10 rectangular bars of dimensions 30 mm (L) x 5 mm (W) x 5 mm (H) from each material were manufactured. Of these 10 bars, 5 bars were fabricated with sharp notch connector and 5 bars were fabricated with round notch connector. The dimensions of all specimens were measured and verified individually by an electronic caliper with an accuracy of 0.05 mm. The radius of each connector was measured with a measuring tool. Results: The failure load was more in Press-R in comparison to Press-S and the difference was found to be statistically significant. The FS was more in CAD-R in comparison to CAD-S and the difference was found to be statistically significant. Conclusion: The round connector design in yittrium stabilized zirconia and heat pressed lithium disilicate both may be considered to be the all-ceramic core material of choice for FDP’s as they have highest failure load and flexural strength.

Influence of thermal and mechanical fatigue on the shear bond strength of different all-ceramic systems.

BackgroundTo evaluate the influence of thermal and mechanical fatigue on the shear bond strength of different all-ceramic cores and veneering porcelain interfaces.Material and MethodsAll-ceramic systems tested were lithium disilicate and zirconia veneered by layering technique. Sixty specimens (n=20) were subjected to shear bond strength. Ten of them were thermal and mechanical cycled. Fracture analysis was performed with stereomicroscopy and scanning electron microscopy. Energy dispersive X-ray spectroscopy analysis was performed across core/veneer interfaces.ResultsThermal and mechanical cycling did not influence on bond strength. However, there was significant difference among systems (<0.01). CoCr group presented the highest values, followed by lithium disilicate, and zirconia. Failure modes were predominantly adhesive for CoCr, cohesive in core for lithium disilicate, and cohesive in veneer for zirconia. Energy dispersive X-ray showed interaction zone for CoCr and lithium disilicate groups and was inconclusive for zirconia. Fatigue had no influence on bond strength of groups tested.ConclusionsThe results suggest that there is a chemical bond between core and veneer materials for CoCr and lithium disilicate groups. Key words:Ceramics, electron microscopy, fatigue, mechanical stress, shear bond strength.

Sodalite zeolite as an alternative all-ceramic infiltrating material for alumina and zirconia toughened alumina frameworks

The purpose of this study was to determine the effects of synthesized sodalite zeolite infiltration achieved by a direct in-situ hydrothermal reaction followed by sintering process on the flexural strength and hardness of alumina and zirconia-toughened alumina (ZTA) frameworks. Ceramic core materials were prepared as disk-shaped specimens with 16mm diameter and 1.2±0.2mm thickness. The case-study group was synthesized sodalite zeolite-infiltrated alumina (IA-SOD) and synthesized sodalite zeolite-infiltrated ZTA (IZ-SOD); and the control group was glass-infiltrated alumina (IA-glass) and glass-infiltrated ZTA (IZ-glass). The biaxial flexural strength (piston-on-three-balls test) and Vickers microhardness were compared among groups (n=10 specimens in each group). Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) were used to investigate the structural characteristics of specimens at the fracture and cross-sectional surfaces. For both IA-SOD and IZ-SOD, the biaxial flexural strength exceeded the required value of 100–150MPa as specified by ISO 6872(2015), indicating their potential as all-ceramic core materials. The flexural strengths and Vickers microhardness of IZ-SOD were respectively 324.7MPa and 1162 VHN, while these values were measured 233.6MPa and 1013 VHN for IA-SOD. The mechanical properties and microstructure of core materials have been advocated as crucial to the clinical performance of all-ceramic dental restorations. This investigation provides data regarding the flexural strength, hardness and microstructure of partially sintered alumina and ZTA frameworks with synthesized sodalite zeolite infiltration.

Effect of femtosecond laser beam angle on bond strength of zirconia-resin cement.

Yttrium-stabilized tetragonal zirconia polycrystalline (Y-TZP) ceramic is widely used as an all-ceramic core material because of its enhanced mechanical and aesthetic properties. The bond strength of Y-TZP restorations affects long-term success; hence, surface treatment is required on ceramic boundaries. This study evaluated the effect of different laser beam angles on Y-TZP-resin cement shear bond strength (SBS). Forty plates of Y-TZP ceramics were randomly assigned to four groups (n = 10). A femtosecond amplifier laser pulse was applied on Y-TZP surface with different incidence angles (90°, 75°, 60°, 45°). The resin cement was adhered onto the zirconia surfaces. The SBS of each sample was measured using universal testing machine at crosshead speed of 1mm/min. The SBS was analyzed through one-way analysis of variance (ANOVA)/Tukey tests. The results showed that the degree of laser beam angle affects the SBS of resin cement to Y-TZP. The laser beam was applied to a surface with a 45° angle which resulted in significantly higher SBS (18.2 ± 1.43MPa) than other groups (at 90° angulation (10.79 ± 1.8MPa), at 75° (13.48 ± 1.2MPa) and at 60° (15.85 ± 0.81MPa); p < 0.001). This study shows that decreasing of the angle between the ceramic surface and the laser beam increased the SBS between the resin cement and the ceramic material, as well as the orifice.

Test of Relative Translucency of 5 All-Ceramic Core Materials

Objective:To study the relative translucency of 5 veneered and glazed all-ceramic systems core material, including Procerra AllCeram Alumina, Vita In-Ceram Zirconium, Ivoclar Vivodent Empress, In-Ceram Spinell and Colored Zirconia. Methods: Under standard black and white background, the surface light reflectivity of 5 veneered all-ceramic systems core material was determined with contact color difference meter, and the ratio of Yb /Yw was calculated. Results: After veneered, the relative translucency of 5 core materials all declined, and ranged from 0.6740 of In-Ceram Spinell to 1.00 of In-Ceram zirconia, among of that In-Ceram Spinell was most transparent. Conclusion: Among the groups, there is no significant differences among Empress II, Procera AllCeram and Colored Zirconia (IL1,IL2,IL3). Compared with Procera AllCeram and Vita In-Ceram Zirconium , Procera AllCeram has significant difference. There is a significant difference between Procera AllCeram and In-Ceram Spinell.

In vitro evaluation of the fracture strength of all-ceramic core materials on zirconium posts.

Objective:For most endodontically treated teeth, tooth-colored post-core systems are preferable for esthetic reasons. Therefore, improvements in material strength must also consider tooth colored post-core complexes. The objective of this study was to evaluate the difference in tooth colored post–core complex strengths.Materials and Methods:A total of 33 human maxillary central incisor teeth were used for this study, with three groups of 11 teeth. Three different methods were used to fabricate all-ceramic post-core restorations: zirconia blanks, Cerec 3D-milled to one-piece post-core restorations (Test Group 1); feldspathic cores (from feldspathic prefabricated CAD/CAM blocks) adhesively luted to CosmoPost zirconia posts (Test Group 2); and IPS Empress cores directly pressed to CosmoPost zirconia posts (Test Group 3). All-ceramic crowns from feldspathic ceramic were constructed using a CAD/CAM system (Cerec 3D) for all specimens. The post-core complexes were tested to failure with the load applied at 45° angled relative to the tooth long axis. The load at fracture was recorded.Results:The maximum fracture strength of the milled zirconia cores (Test Group 1) was 577 N; corresponding values for the milled feldspathic cores (Test Group 2) and the pressed cores (Test Group 3) were 586 and 585 N, respectively. Differences were not statistically significant at P < 0.05 (P = 0.669).Conclusions:All-ceramic cores adhesively luted on zirconia posts and one-piece all-ceramic zirconium post–core structures offer a viable alternative to conventional pressing.

Bond Strength of the Porcelain Repair System to All‐Ceramic Copings and Porcelain

The purpose of this study was to investigate the shear bond strength of the porcelain repair system on alumina and zirconia core ceramics, comparing this strength with that of veneering porcelain. Veneering ceramic (n = 12), alumina core (n = 24), and zirconia core (n = 24) blocks measuring 10 × 5 × 5 mm(3) were fabricated. Veneering ceramic blocks were used as the control. Alumina and zirconia core blocks were divided into 2 groups (n = 12 each), and a slot (2 × 2 × 4 mm(3)) filled with veneering ceramics was prepared into one of the alumina and zirconia core groups (n = 12). Followed by surface treatments of micro-abrasion with 30 μm alumina particles, etching with 35% phosphoric acid and silane primer and bond, composite resin blocks (2 × 2 × 2 mm(3)) were built up and light polymerized onto the treated surfaces by 3 configurations: (a) composite blocks bonded onto veneering ceramic surface alone, (b) composite blocks bonded onto alumina core or zirconia core surfaces, (c) a 50% surface area of the composite blocks bonded to veneering ceramics and the other 50% surface area of the composite blocks to alumina core or zirconia core surfaces. The shear bond strength of the composite to each specimen was tested by a universal testing machine at a 0.5 mm/min crosshead speed. The shear bond strength was analyzed by unpaired t-tests for within the configuration groups and ANOVA for among the different configuration groups. When the mean shear bond strength was compared within groups of the same configuration, there were no statistically significant differences. Comparison of the shear bond strength among groups of different configurations revealed statistically significant differences. The mean shear bond strength of composite onto 100% veneering ceramic surface and composite onto 50% veneering 50% all-ceramic cores was statistically higher than that of composite onto 100% all-ceramic cores; however, the differences of the shear bond strength of composite bonded only onto the veneering ceramic surface were not statistically significant from those of 50% surface area of composite bonded onto all-ceramic cores. No statistically significant differences in the bond strength of a porcelain repair system to alumina and zirconia copings were observed. Increasing the surface of veneering ceramics to a porcelain repair system improved the repair material's bond strength.

Test of Relative Translucency for Four All-Ceramic Core Material after Veneering Ceramic

Objective: To study the relative translucency of 4 veneered and glazed all-ceramic systems core material, including Vita In-Ceram Alumina, Vita In-Ceram Zirconium, Ivoclar Vivodent Empress and Colored Zirconia. Methods: Under standard black and write background, the surface light reflectivity of 4 veneered all-ceramic systems core material was determined with contact color difference meter, and the ratio of Yb /Yw was calculated. Results: After veneered, the relative translucency of 4 core materials all declined, and ranged from 0.8015 of Colored Zirconia to 1.00 of In-Ceram zirconia, among of that Empress II and Colored Zirconia were most transparent. Conclusion: Among the groups, there is no significant difference between Empress II and Colored Zirconia(IL1,IL2,IL3). Compared with Vita In-Ceram Alumina and Vita In-Ceram Zirconium, Vita In-Ceram Alumina(AL1) has significant difference. There is no significant difference between Vita In-Ceram Zirconium and Vita In-Ceram Alumina(AL2,AL3,AL4).

Effect of Post-Core Materials on the Color Value of Four Dental All-Ceramic Cores

The aim of this study were to compare the color value of four kinds of dental all-ceramic cores (IPS e.max Press,Zenostar,Lava Zirconia and Upcera Zirconia) on three different post-core materials.All-ceramic core materials were made into samples at the diameter of 10mm and the thickness of 0.50.02mm.Their color value on the post-core material of noble metal,Co-Cr alloy and resin were respectively determined with chromatism instrument.It was showed that the color value of four all-ceramic cores were statistically different.IPS e.max Press was most obviously affected by post-core materials,while Upcera Zirconia the weakest.Lava Zirconia and Zenostar were influenced to a certain degree.In conclusion,non-mental post-core was preferable for IPS e.max Press,Upcera Zirconia was fit for any post-core materials.

A Comparative Study on Relative Translucency of Four Dental All-Ceramic Core Materials

The aim of this study were to compare the relative translucency of four dental all-ceramic core materialsIPS e.max Press,Zenostar,Lava Zirconia and Upcera Zirconia.All core materials were fabricated into samples at the diameter of 10mm and the thickness of 0.50.02mm.The relative translucency of samples were determined with color difference meter and analysed with SPSS 13.0 software.It was showed that the relative translucency of 4 all-ceramic core materials were statistically different.There was a decreasing order of their relative translucency,IPS e.max PressLava Zirconia ZenostarUpcera Zirconia.IPS e.max Press has the hightest translucency,and it was advisably used to restore anterior tooth.Upcera Zirconia was the most opaque of 4 all-ceramic core materials,and it was suitable for post tooth.

Comparing Study on Translucency of Four Veneered Dental All-Ceramic Core Materials

This study aimed to compare the translucency of four veneered dental all-ceramic core materials,including IPS e.max Press,Zenostar,Lava Zirconia and Upcera Zirconia.All specimens were fabricated at 10mm in diameter and 1.00.01mm in thickness.The translucency of specimens were measured with color difference meter and measurements were statistically analysed with SPSS 13.0. Experimental results showed that their translucency had significant difference,the order of relative translucency from high to low was IPS e.max PressLava ZirconiaZenostarUpcera Zirconia.IPS e.max Press which has good optical effect may be preferable for restoring anterior tooth with higher translucent. As for relatively opaque posterior tooth,Upcera Zirconia may be advisable.

Comparing Study on Transmittance of Four Dental All-Ceramic Core Material

The purpose of this study was to compare the transmittance of four dental all-ceramic core materials at clinical recommendation thickness.Specimens with 10mm in diameter and 0.50.01mm in thickness,including IPS e.max Press,Zenostar Zirconia,Lava Zirconia and Upcera Zirconia,were fabricated.The transmittance of specimens were measured with PR2650 spectrophotometer and measurements were analysed statistically with SPSS13.0.Experimental results showed that they had significantly different transmittance.There was a decreasing order,IPS e.max Press Lava Zirconia Zenostar Zirconia Upcera Zirconia,which were 6.1136.750 for IPS e.max,1.6042.135 for Lava Zirconia,1.5782.117 for Zenostar Zirconia and 0.9951.265 for Upcera Zirconia.

The Influence of Background Color to 3 All-Ceramic System Core Materials

To study the influence of background color to 3 all-ceramic system core materials.The chromaticity value of all samples that were put on noble metal, Ni-Cr alloy, Hg-Ag alloy and resign background were measured with chromatism instrument, and chromatic aberration among groups were calculated. The chromatic aberration of Empress II samples on different background color could be distinguished by human eyes, but those of Alumina and Zirconium were unable to being distinguished. In conclusion, the influence of background color to Empress II and In-Ceram Alumina of AL1 were lager. When chosen as core material, noble metals should be covered to keep prosthesis from clinical color-transform. As background to In-Ceram Alumina of AL2, it was unnecessary for resin to be covered. In-Ceram Alumina of AL3, AL4 and In-Ceram Zirconium weren’t affected by background color.

The Transmittance Test of 3 All-Ceramic System Core Materials

This experiment was to study the transmittance of 3 all-Ceramic system core materials, including 4 colors of Vita In-ceram Alumina,4 colors of Vita In-Ceram Zirconium and 3 colors of Empress II,and to provide basis for clinical choice of core materials.With Vita alpha veneer porcelain as control,the transmittance of all samples was determined with spectrophotometer under D65 standard source.The transmittance of materials was 1.434%~3.843% for Vita In-Ceram Alumina,0~0.587% for Vita In-Ceram Zirconium,5.620%~6.665% for Empress II.As a whole,the transmittance of Empress IIwas the best of 3 core materials,that of In-Ceram Alumina was the worse,that of Vita In-Ceram Zirconium was the worst.

Effect of surface treatment methods on the shear bond strength between resin cement and all-ceramic core materials

This study compared the influence of various surface treatments on the shear bond strength between resin cement and lithium disilicate glass-ceramics. A series of 120 lithium disilicate ceramic samples were prepared to compare the effect of different surface treatments on the shear strength of a luting cement bonded to two all-ceramic systems. IPS Empress 2 and IPS e.max Press ceramic samples were fabricated according to the manufacturer's instructions. The ceramic samples were divided into the following 6 surface treatment groups for each ceramic system: 1—no treatment (C), 2—airborne-particle abrasion (A), 3—acid etching (E), 4—airborne-particle abrasion+acid etching (AE), 5—Nd:YAG laser (L), 6—Nd:YAG laser+acid etching (LE). Resin cement was then bonded to the treated ceramic surfaces and light polymerized. The shear bond strengths of the specimens were measured using a universal testing machine. Two-way ANOVA and Tukey HSD (α=0.05) test were used to determine differences in shear bond strength between the groups. The ANOVA revealed significant differences between the treatment groups and ceramic types (p<0.05). The shear bond strengths of IPS Empress 2 were significantly higher than those of IPS e.max Press.

A Comparative Shade Evaluation of Two Different All-Ceramic Materials over Three Core Build-up Materials: An in vitro Study

ABSTRACTAimTo evaluate and compare the shade of zirconia and alumina crowns over composite, all-ceramic and metal core material.Objectives(1) To evaluate the influence of composite core build-up material on the shade of zirconia and alumina crowns. (2) To evaluate the influence of all-ceramic core material on the shade of zirconia and alumina crowns. (3) To evaluate the influence of metal core material on the shade of zirconia and alumina crowns. (4) To compare the influence of composite, all-ceramic and metal core material on the shade of zirconia and alumina crowns.Materials and MethodsThe all-ceramic materials used for fabrication of crowns were zirconia (LAVA) and alumina (PROCERA). They were evaluated spectrophotometrically for the change in shade when placed over three core build-up materials.ResultsThe observations obtained were statistically analyzed by analysis of variance. Zirconia crowns when compared with alumina crowns showed the least shade change when placed on the three core materials. Among the three core materials used, composite core build-up material showed the least change in the shade.ConclusionZirconia crowns showed least shade change when placed on the three core materials.How to cite this articleBatra P, Ram SM. A Comparative Shade Evaluation of Two Different All-Ceramic Materials over Three Core Build-up Materials: Anin vitroStudy. J Contemp Dent 2012;2(2):15-21.

Spectral Transmittance of Six All-Ceramic Core Materials after Veneering Ceramic

The spectral transmittance of six kinds of Vita In-Ceram and Cercon all-ceramic core materials after veneering ceramic was determined. Based on the production method recommended by the manufacturer, specimens of the same thickness are made. PERKIN ELMER Spectrophotometer is adopted to measure the spectral transmittance of In-Ceram AL2 slip-casting glass/alumina composite, AL2 electroformed alumina, Z21 slip-casting glass/zirconia composite, Z21 electroformed zirconia, Cercon base color zirconia and Cercon base zirconia all-ceramic core materials, after veneering ceramic. The results show that, after veneering ceramic, Cercon base Zirconia has the highest spectral transmittance, followed by AL2 Electroformed Alumina and Z21 Electroformed Zirconia, whereas the transmittance of Z21 slip-casting Glass/Zirconia composite has the lowest. Statistical data show that, among the groups, In-Ceram slip-casting Glass/Alumina composite (AL2), Electroformed Alumina (AL2), Cercon base color Zirconia and Cercon base Zirconia have significant differences between every group. On the other hand, there is no significant difference between In-Ceram slip-casting Glass/Zirconia composite (Z21) and Electroformed Zirconia (Z21). Therefore, we should choose all-ceramic restoration materials based on the spectral transmittance of all-ceramic core materials after veneering ceramic and transparency of the remaining natural teeth of patients.

Effect of Background Color on In-Ceram and Cercon All-Ceramic Core Material

The present paper probes into the effect of background color of different post-core materials on the core materials of In-Ceram AL2 Electroformed Alumina, Z21 Electroformed Zirconia, Cercon base color Zirconia, and Cercon base Zirconia. The spectrocolorimeter was used to measure colorimetric values of all groups of samples against the background of noble metal, nickel-chromium alloy, silver amalgam and resin, and to calculate the color difference among the groups. The result showed that the color difference of Cercon base color Zirconia viewed against different backgrounds was identifiable by human eyes (ΔE &gt; 1.5). In contrast, the color differences of In-Ceram AL2 Electroformed Alumina, Z21 Electroformed Zirconia and Cercon base Zirconia viewed against different backgrounds were unidentifiable by human eyes (ΔE &lt; 1.5). Based on this, it can be stated that Cercon base color Zirconia is significantly affected by background color. Thus, proper method to shelter the background color should be adopted. In addition, AL2 Electroformed Alumina, Z21 Electroformed Zirconia, and Cercon base color Zirconia are less influenced by the background color, thus it is not necessary to cover the background color.

Influence of the supporting die structures on the fracture strength of all-ceramic materials

This study investigated the influence of the elastic modulus of supporting dies on the fracture strengths of all-ceramic materials used in dental crowns. Four different types of supporting die materials (dentin, epoxy resin, brass, and stainless steel) (24 per group) were prepared using a milling machine to simulate a mandibular molar all-ceramic core preparation. A total number of 96 zirconia cores were fabricated using a CAD/CAM system. The specimens were divided into two groups. In the first group, cores were cemented to substructures using a dual-cure resin cement. In the second group, cores were not cemented to the supporting dies. The specimens were loaded using a universal testing machine at a crosshead speed of 0.5 mm/min until fracture occurred. Data were statistically analyzed using two-way analysis of variance and Tukey HSD tests (α = 0.05). The geometric models of cores and supporting die materials were developed using finite element method to obtain the stress distribution of the forces. Cemented groups showed statistically higher fracture strength values than non-cemented groups. While ceramic cores on stainless steel dies showed the highest fracture strength values, ceramic cores on dentin dies showed the lowest fracture strength values among the groups. The elastic modulus of the supporting die structure is a significant factor in determining the fracture resistance of all-ceramic crowns. Using supporting die structures that have a low elastic modulus may be suitable for fracture strength tests, in order to accurately reflect clinical conditions.

Test of Relative Translucency for Three Veneered All-Ceramic Systems Core Material

Objective: To study the relative translucency of 3 veneered and glazed all-ceramic systems core material, including Vita In-Ceram Alumina, Vita In-Ceram Zirconium and Ivoclar Vivodent Empress. Methods: Under standard black and write background, the surface light reflectivity of 3 veneered all-ceramic systems core material was determined with contact color difference meter, and the ratio of Yb /Yw was calculated. Results: After veneered, the relative translucency of 3 core materials all declined, and ranged from 0.8880 of Empress II to 1.00 of In-Ceram zirconia, among of that Empress II was most transparent. Conclusion: The relative translucency of 3 veneered all-ceramic systems core material had significant statistical difference. There was a decreasing range as Vitadur Alpha dentin (standard) &gt; Empress II (0.8 mm) &gt; In-Ceram Alumina &gt; In-Ceram Zirconia.