Fracture strength of 5 different all-ceramic crown systems

PURPOSE: The purpose of this study was to evaluate the fracture resistance of 5 different all-ceramic crown systems (In-Ceram, Empress staining technique, Empress veneering technique, Celay feldspathic system, and Celay In-Ceram system) before and after cyclic preloading in an artificial mouth. MATERIALS AND METHODS: Extracted natural maxillary incisors were prepared with a 90-degree shoulder. The crowns were adhesively luted to the abutments using dual-cured composite cement. Half of the specimens were artificially aged via a chewing simulation and thermocycling, and all specimens were tested for fracture strength. The results were compared with those of porcelain-fused-to-metal (PFM) crowns with circular porcelain-butt margins that were cemented with zinc phosphate cement. RESULTS: The chewing simulation and the thermocycling significantly decreased the fracture strength of all tested crown systems (P < 0.01). There were no statistically significant differences between the all-ceramic crown groups and the PFM crowns. CONCLUSION: All-ceramic crowns can be used for anterior restorations. However, in vivo investigations of all-ceramic crown systems should be undertaken before introducing them into routine clinical use.     

Fracture strength of copy-milled and conventional In-Ceram crowns

The purpose of this study was to compare the fracture resistance of copy-milled and conventional In-Ceram crowns. Four groups of 10 uniform sized all-ceramic anterior crowns were fabricated for this test: (1) In-Ceram Spinell (2) In-Ceram Alumina (3) Celay In-Ceram Spinell, and (4) Celay In-Ceram Alumina crowns. All specimens were cemented on stainless steel master die with resin cement and stored in 37 degrees C water for one day prior to loading into a universal testing machine. Using a steel ball at a crosshead speed of 0.5 mm min-1, the crowns were loaded at 30 degrees C angle until catastrophic failure occurred. Mean fracture strength was analysed and compared. Under the conditions of this study and the materials used, the following conclusions were drawn: 1. The strength of Celay In-Ceram anterior crowns had a slightly higher fracture strength than conventional In-Ceram crowns. 2. In-Ceram Alumina crowns had a significantly higher fracture strength than In-Ceram Spinell crowns in both conventional and copy milling methods.     

Fracture resistance of three all-ceramic restorative systems for posterior applications

STATEMENT OF PROBLEM: The failure loads of all-ceramic crowns are influenced not only by the fracture resistance of the component materials but also by prosthesis geometry and size and location of flaws, thus there is a need for a study that compares the fracture resistance of all-ceramic systems using a simple and reproducible specimen geometry that includes flaws occurring at material interfaces. PURPOSE: The research aim was to compare the in vitro fracture resistance and origin of failure of simulated first molar crowns fabricated using 3 all-ceramic systems, IPS Empress 2, Procera AllCeram, and In-Ceram Zirconia. MATERIAL AND METHODS: Twenty axisymmetric crowns of each system were fabricated to fit a preparation with 1.5- to 2.0-mm occlusal reduction. The center of the occlusal surface on each of 15 specimens per ceramic system was axially loaded to fracture in a universal testing machine, and the maximum load (N) was recorded. Fractured surfaces were examined using optical and electron microscopy to determine the most prevalent origin of failure in each ceramic system. Five crowns per system were sectioned, and thickness of the luting agent, core material, and veneer porcelain layers were measured. The 95% confidence intervals of the Weibull modulus and characteristic failure load were compared between the 3 systems. Two-way multivariate analysis of variance was used to analyze the thickness of the luting agent, ceramic core, and veneer porcelain layers (alpha=.05). RESULTS: The 95% confidence intervals for Weibull modulus were 1.8 to 2.3 (IPS Empress 2), 2.8 to 3.6 (Procera AllCeram), and 3.9 to 4.9 (In-Ceram Zirconia). The 95% confidence intervals for characteristic failure load were 771 to 1115 N (IPS Empress 2), 859 to 1086 N (Procera AllCeram), and 998 to 1183 (In-Ceram Zirconia). The origin of failure was most commonly found at the interface between the ceramic core and veneer porcelain for IPS Empress 2 and between the ceramic core and luting agent layer for the other systems. CONCLUSIONS: There was no significant difference in fracture resistance; however, there was a significant difference in failure origin between the all-ceramic systems studied.     

Biaxial flexural strength of Turkom-Cera core compared to two other all-ceramic systems

Advances in all-ceramic systems have established predictable means of providing metal-free aesthetic and biocompatible materials. These materials must have sufficient strength to be a practical treatment alternative for the fabrication of crowns and fixed partial dentures.

Objectives

The aim of this study was to compare the biaxial flexural strength of three core ceramic materials.

Material and methods

Three groups of 10 disc-shaped specimens (16 mm diameter x 1.2 mm thickness - in accordance with ISO-6872, 1995) were made from the following ceramic materials: Turkom-Cera Fused Alumina [(Turkom-Ceramic (M) Sdn Bhd, Puchong, Selangor, Malaysia)], In-Ceram (Vita Zahnfabrik, Bad Säckingen, Baden-Württemberg, Germany) and Vitadur-N (Vita Zahnfabrik, Bad Säckingen, Baden-Württemberg, Germany), which were sintered according to the manufacturer''s recommendations. The specimens were subjected to biaxial flexural strength test in a universal testing machine at a crosshead speed of 0.5 mm/min. The definitive fracture load was recorded for each specimen and the biaxial flexural strength was calculated from an equation in accordance with ISO-6872.

Results

The mean biaxial flexural strength values were: Turkom-Cera: 506.8±87.01 MPa, In-Ceram: 347.4±28.83 MPa and Vitadur-N: 128.7±12.72 MPa. The results were analyzed by the Levene''s test and Dunnett''s T3 post-hoc test (SPSS software V11.5.0 for Windows, SPSS, Chicago, IL, USA ) at a preset significance level of 5% because of unequal group variances (P<0.001). There was statistically significant difference between the three core ceramics (P<0.05). Turkom-Cera showed the highest biaxial flexural strength, followed by In-Ceram and Vitadur-N.

Conclusions

Turkom-Cera core had significantly higher flexural strength than In-Ceram and Vitadur-N ceramic core materials.     

三种全瓷基底与其相应饰面瓷的结合性能研究

目的:测试并比较3种全瓷基底材料与其相应饰面瓷的结合强度,为临床选择合适的修复材料提供依据。方法:将成品Lava Frame、Vita In-Ceram Alumina、IPS EmpressⅡ瓷块、StarLoy钴铬合金制成长方体试件,分别在其表面烧结相应的饰面瓷,测试抗剪切强度,激光共聚焦扫描显微镜和扫描电镜观察破坏模式。结果:Lava、Vita、IPS EmpressⅡ、金瓷复合体的抗剪强度值分别为11.40±1.08、9.44±1.23、25.56±1.70、27.02±2.06MPa。IPS EmpressⅡ、金瓷复合体的抗剪切强度显著高于Lava和Vita(P<0.05);IPS EmpressⅡ与金瓷复合体的抗剪切强度差异无统计学意义(P>0.05);Lava与Vita差异无统计学意义(P>0.05)。IPS Em-pressⅡ的破坏模式以基底材料破坏为主,Lava、Vita、金瓷复合体以饰面瓷破坏为主。结论:IPS EmpressⅡ基底与饰面瓷的结合强度最高,与金瓷复合体无差别。     

Fracture strength of teeth restored with all-ceramic posts and cores.

OBJECTIVE: The purpose of this in vitro investigation was to evaluate the fracture strength of endodontically treated teeth restored with different all-ceramic posts and cores. METHOD AND MATERIALS: Seventy-two endodontically treated human maxillary central incisors were divided into 3 groups with 24 teeth each and restored with 1 of the following methods: prefabricated zirconia ceramic posts and resin composite buildups; zirconia ceramic posts and copy-milled alumina ceramic cores (2-piece technique), or copy-milled all-ceramic posts and cores made from a zirconia-reinforced glass-infiltrated alumina ceramic (1-piece technique). Each group was divided into 3 subgroups of 8 samples each, consisting of teeth that did not receive crown restorations and were stored for 60 days, teeth restored with all-ceramic crowns and stored for 60 days, and teeth restored with all-ceramic crowns and subjected to 1.2 million loading cycles with 30 N in a chewing simulator. RESULTS: The mean fracture strengths ranged from 205 to 522 N. Prefabricated zirconia posts and resin composite buildups showed a statistically significantly lower fracture strength after chewing simulation than teeth restored with prefabricated zirconia posts and alumina ceramic cores. CONCLUSION: All-ceramic posts and cores made with the 2-piece technique showed promising fracture strengths under the tested conditions.     

Fracture strength of all-ceramic crowns with varying core elastic moduli

The aim of this study was to investigate the fracture strength of aluminous porcelain jacket crowns on core structures with different elastic moduli. Forty standardized aluminous porcelain jacket crowns were fabricated and divided into four groups. Each crown was luted with zinc phosphate cement onto a master die with a known elastic modulus, and loaded until failure occurred. The fracture load was shown to increase with increasing elastic modulus of the core. Analysis of data by ANOVA revealed a significant difference (p < 0.05) between the four groups. The results suggested that core elastic modulus may have an influence on the fracture resistance of aluminous porcelain jacket crowns, and it may be appropriate to recommend the use of high modulus metals for core placement on teeth to be restored with all-ceramic crowns.     

Flexural strength of In-Ceram alumina and In-Ceram zirconia core materials

PURPOSE: The study compared the flexural strength of In-Ceram alumina and In-Ceram zirconia systems. The probability of failure of the two glass-infiltrated ceramic core materials was analyzed with and without lamination with Vitadur-alpha porcelain. MATERIALS AND METHODS: Ten uniform beams of core materials as well as 10 beams of laminated core materials were fabricated for In-Ceram alumina and In-Ceram zirconia. The samples were subjected to three-point bending tests. Flexural strength for both ceramic core materials was determined with and without their porcelain laminations. The strength data were analyzed using the Weibull method. Modes of failure for both systems were determined using scanning electron micrography. RESULTS: The strength of the In-Ceram zirconia system was significantly higher than In-Ceram alumina when comparing their core materials with and without porcelain lamination. The failure mode for both systems was predominantly transgranular fracture of alumina platelets. CONCLUSION: In-Ceram zirconia demonstrated higher flexural strength than In-Ceram alumina.     

Fracture strength of all-ceramic posterior inlay-retained fixed partial dentures

OBJECTIVES: The purpose of this in vitro study was to compare the quasi-static (QSFS) and fatigue fracture strength of all-ceramic resin-bonded three unit inlay-retained fixed partial dentures (IRFPDs) made from a heat-pressed lithium-disilicate based glass-ceramic (LDGC) and a CAD/CAM-manufactured yttrium-oxide partially stabilized zirconia framework (YPSZ). METHODS: Identical IRFPD-models of the maxilla were used. They consisted of a second premolar, a missing first molar and a second molar (Co-Cr-Mo alloy) integrated in a low melting alloy base. Roots were covered with a soft silicone-layer to simulate an artificial parodontium. Premolars had an occlusal-distal inlay-preparation and molars a mesial-occlusal inlay-preparation. Thirty-two IRFPDs were made from each ceramic using two different connector dimensions: 3mmx3mm (LDGC_9, YPSZ_9); 4mmx4mm (LDGC_16, YPSZ_16). All IRFPDs were cemented adhesively to the IRFPD-models, using composite resin cement. QSFS was tested in a universal-testing-machine (UTM) for six specimens. The other specimens were fatigued either with cyclic loading at 250N (n=4) in a chewing simulator or at 600N (n=6) using the UTM, and group YPSZ additionally at 1500N. RESULTS: The medians of QSFS (N) were 960 (LDGC_9), 1316 (LDGC_16), 3180 (YPSZ_9) and 3120 (YPSZ_16). For both QSFS and cyclic loading significant differences were found between LDGC_9 and LDGC_16 (p0.05). Differences between LDGC and YPSZ were significant for both connector sizes (p相似文献   

Fracture strength of all-ceramic crowns luted using two bonding methods

STATEMENT OF THE PROBLEM: Excellent esthetic quality is one of the major advantages of all-ceramic restorations; however, catastrophic fracture of such restorations is still a disadvantage. Ceramic bonding systems using ceramic primers without the use of hydrofluoric acid have been introduced, but data about the efficiency of these systems are lacking. PURPOSE: This study investigated the influence of 2 bonding procedures on the fracture resistance of low-fusing ceramic and computer aided design-computer aided manufacturing (CAD-CAM) all-ceramic crowns. MATERIAL AND METHODS: Forty-two standardized all-ceramic crowns were fabricated on human maxillary premolars. Seven unprepared maxillary premolars were used as control. Three all-ceramic crown systems were used: 1 low-fusing ceramic (Duceram) and 2 machineable ceramics (Vita Mark II and ProCAD) using the Cerec 3 CAD-CAM system. The intaglio surfaces of fabricated crowns (n=7) were subjected to 2 different conditioning techniques: etching, using 4.9% hydrofluoric acid followed by application of Mirage ABC silane, or cleaning, using 65% phosphoric acid and application of primer (Porcelain Liner-M). The crowns were luted to the teeth using Superbond C&B luting agent. After 24 hours storage in water, specimens were loaded in a universal testing machine with the compressive load applied along the long axis of the specimen at a crosshead speed 1 mm/min until fracture. Fracture loads (N) were recorded. One-way analysis of variance (ANOVA) and the Tukey HSD test (alpha=.05) were used for statistical analysis of the data. RESULTS: The mean fracture load of control specimens (738.3+/-195.3 N) was not significantly different from that of the 2 CAD-CAM crowns (667.7+/-72.3 N, 715.9+/-105.2 N). However, fracture load of natural teeth and the 2 CAD-CAM crowns was significantly higher than the fracture load of the low-fusing ceramic crowns treated with HF acid and silane (465.5+/-101.1 N) and, when cleaned, using phosphoric acid and an application of primer (447.5+/-63.4 N) (P<.05). There was no significant difference in the mean fracture load of each ceramic material when bonded using the 2 different procedures, either treated with HF acid and silane or cleaned using phosphoric acid and application of primer (P>.05). CONCLUSION: The application of a primer (Procelain Liner-M) was an effective method for treating the intaglio surface of all-ceramic crowns before cementation.     

Five-year evaluation of posterior all-ceramic three-unit (In-Ceram) FPDs

PURPOSE: The purpose of this study was to investigate whether the properties of the In-Ceram material are adequate for use in posterior three-unit fixed partial dentures (FPD) and to evaluate the clinical method regarding preparation technique, design, and choice of cement. MATERIALS AND METHODS: Eighteen patients were treated with a total of 20 posterior three-unit FPDs according to the In-Ceram technique. The FPDs were constructed with bilateral support and one pontic and were all replacing one premolar or a molar (11 replacing premolars and 9 replacing molars). They were evaluated 6 months after delivery and then once yearly. RESULTS: Eighteen of the 20 FPDs (90%) showed no defects at any of the follow-up examinations and were functioning well after 5 years. No caries or signs of gingivitis or periodontitis exceeding those found in the rest of the dentition were registered. CONCLUSION: The In-Ceram technique is, in a 5-year perspective and adopted for three-unit FPDs, an acceptable treatment alternative. Further studies must, however, be performed before the material can be recommended for more extensive restorations than the FPDs included in this study.     

Fracture toughness and hardness evaluation of three pressable all-ceramic dental materials

OBJECTIVES: This study evaluates the fracture toughness and hardness of three pressable all-ceramic materials: IPS-Empress, Empress 2 and an experimental ceramic material. METHODS: Fifteen discs and 15 bars per material were prepared. Fracture toughness was measured with two different techniques: indentation fracture and indentation strength. During the indentation fracture tests the hardness of each material was also measured. Statistical significance among groups of population was studied using one-way Anova and Tukey's multiple comparison tests. RESULTS: Fracture toughness results using the indentation strength technique (with three-point bending and biaxial flexure tests) were: IPS-Empress (1.39 (SD 0.3) and 1.32 (SD 0.3)); Empress 2 (3.14 (SD 0.5) and 2.50 (SD 0.3)) MPa x m(1/2); and the experimental ceramic (3.32 (SD 0.6) and 2.43 (SD 0.3)) MPa x m(1/2). The indentation fracture technique generated orthogonal cracks of different lengths for Empress 2 and the experimental ceramic, whether perpendicular or parallel to the lithium disilicate elongated crystals. Thus, two values were reported: Empress 2 (1.5 (SD 0.2) and 1.16 (SD 0.2)) MPa x am(1/2) and the experimental ceramic (1.67 (SD 0.3) and 1.15 (SD 0.15)) MPa x m(1/2). The IPS-Empress indentation fracture result was 1.26 (SD 0.1). The hardness results were: 6.6, 5.3 and 5.5 GPa for IPS-Empress, Empress 2 and the experimental ceramic, respectively. CONCLUSIONS: No significant differences in fracture toughness and hardness results were found between Empress 2 and the experimental ceramic (P>0.05 ANOVA). Both materials exhibited fracture toughness anisotropy following pressing. They demonstrated improved fracture toughness and reduced hardness compared with IPS-Empress P<0.05(ANOVA), which should be beneficial for clinical applications.     

In vitro fracture strength of teeth restored with different all-ceramic crown systems

STATEMENT OF PROBLEM: There is insufficient knowledge of the strength of all-ceramic crowns bonded to natural teeth to warrant the use of all-ceramic crowns in place of metal-ceramic crowns. PURPOSE: The purpose of this study was to evaluate and compare fracture resistance of crowns made of 3 different types of 2 all-ceramic crown systems-0.4-mm and 0.6-mm aluminum oxide coping crowns and zirconia ceramic coping crowns-and metal-ceramic crowns. MATERIAL AND METHODS: Forty intact, noncarious human maxillary central incisors were divided into 4 groups (n=10): Group MCC (control), metal-ceramic crown (JRVT High Noble Alloy); Group AC4, crown with 0.4-mm aluminum oxide coping (Procera AllCeram); Group AC6, crown with 0.6-mm aluminum oxide coping (Procera AllCeram); and Group ZC6, crown with 0.6-mm zirconia ceramic coping (Procera AllZirkon). Teeth were prepared for complete-coverage all-ceramic crowns so that a final dimension of 5.5 +/- 0.5 mm was achieved incisocervically, mesiodistally, and faciolingually. A 1.0-mm deep shoulder finish line was used with a rounded internal line angle. All restorations were treated with bonding agent (Clearfil SE Bond) and luted with phosphate-monomer-modified adhesive cement (Panavia 21). Fracture strength was tested with a universal testing machine at a crosshead speed of 2 mm per minute with an angle of 30 degrees to the long axis of the tooth after restorations were stored in 100% relative humidity of a normal saline solution for 7 days. The mode of fracture was examined visually. Means were calculated and analyzed with 1-way ANOVA and Tukey's HSD (alpha=.05). RESULTS: The means of fracture strength were: Group MCC, 405 +/- 130 N; Group AC4, 447 +/- 123 N; Group AC6, 476 +/- 174 N; and Group ZC6, 381 +/- 166 N. There was no significant difference between groups ( P =.501). The mode of failure for all specimens was fracture of the natural tooth. CONCLUSIONS: There was no significant difference in the fracture strength of the teeth restored with all-ceramic crowns with 0.4- and 0.6-mm aluminum oxide copings, 0.6-mm zirconia ceramic copings, and metal ceramic crowns.     

Fracture strength of monolithic all-ceramic crowns made of high translucent yttrium oxide-stabilized zirconium dioxide compared to porcelain-veneered crowns and lithium disilicate crowns

Objective. The aim of the study was to provide data on the fracture strength of monolithic high translucent Y-TZP crowns and porcelain-veneered high translucent Y-TZP crown cores and to compare that data with the fracture strength of porcelain-veneered Y-TZP crown cores and monolithic lithium disilicate glass-ceramic crowns. Materials and methods. Sixty standardized crowns divided into six groups (n = 10) were fabricated: monolithic high translucent Y-TZP crowns, brand A, monolithic high translucent Y-TZP crowns, brand B, veneered high translucent Y-TZP crown cores, brand A, veneered high translucent Y-TZP crown cores, brand B, heat-pressed monolithic lithium disilicate crowns and veneered Y-TZP crown cores. All crowns were thermocycled, cemented onto dies, cyclically pre-loaded and finally loaded to fracture. Results. The monolithic Y-TZP groups showed significantly higher fracture strength (2795 N and 3038 N) compared to all other groups. The fracture strength in the veneered Y-TZP group (2229 N) was significantly higher than the monolithic lithium disilicate group (1856 N) and the veneered high translucent Y-TZP groups (1480 N and 1808 N). Conclusions. The fracture strength of monolithic high translucent Y-TZP crowns is considerably higher than that of porcelain-veneered Y-TZP crown cores, porcelain-veneered high translucent Y-TZP crown cores and monolithic lithium disilicate crowns. The fracture strength of a crown made of monolithic high translucent Y-TZP is, with a large safety margin, sufficient for clinical use for the majority of patients. Porcelain-veneered Y-TZP crown cores show higher fracture resistance than monolithic lithium disilicate crowns.     

In vitro marginal fit of three all-ceramic crown systems

STATEMENT OF PROBLEM: Studies on marginal discrepancies of single restorations using various systems and materials have resulted in statistical inferences that are ambiguous because of small sample sizes and limited numbers of measurements per specimen. PURPOSE: The purpose of this study was to compare the marginal adaptation of single anterior restorations made using different systems. MATERIAL AND METHODS: The in vitro marginal discrepancies of 3 different all-ceramic crown systems (Celay In-Ceram, conventional In-Ceram, and IPS Empress 2 layering technique), and a control group of metal ceramic restorations were evaluated and compared by measuring the gap dimension between the crowns and the prepared tooth at the marginal opening. The crowns were made for 1 extracted maxillary central incisor prepared with a 1-mm shoulder margin and 6-degree tapered walls by milling. Thirty crowns per system were fabricated. Crown measurements were recorded with an optical microscope, with an accuracy of +/-0.1 microm, at 50 points spaced approximately 400 microm along the circumferential margin. The criterion of 120 microm was used as the maximum clinically acceptable marginal gap. Mean gap dimensions and standard deviations were calculated for marginal opening. The data were analyzed with a 1-way analysis of variance (alpha=.05). RESULTS: Mean gap dimensions and standard deviations at the marginal opening for the incisor crowns were 87 +/- 34 microm for control, 83 +/- 33 microm for Celay In-Ceram, 112 +/- 55 microm for conventional In-Ceram, and 46 +/- 16 microm for the IPS Empress 2 layering technique. Significant differences were found among the crown groups (P<.05). Compared with the control group, the IPS Empress 2 group had significantly smaller marginal discrepancies (P<.05), and the conventional In-Ceram group exhibited significantly greater marginal discrepancies (P<.05). There was no significant difference between the Celay In-Ceram and the control group. CONCLUSION: Within the limitations of this study, the marginal discrepancies were all within the clinically acceptable standard set at 120 microm. However, the IPS Empress 2 system showed the smallest and most homogeneous gap dimension, whereas the conventional In-Ceram system presented the largest and more variable gap dimension compared with the metal ceramic (control) restoration.     

Vita In-Ceram全瓷修复体2年临床观察

目的 探讨Vita In-Ceram Alumina渗透陶瓷全瓷修复体的修复效果,为临床应用提供参考。方法 45例门诊患者,修复体共194件,其中上颌124件,下颌70件。前牙全冠165个,后牙全冠21个,前牙固定桥8个。通过3－24个月的观察,采用美国加利福尼亚科学会的质量评价体系对Vita In-Ceram Alumina渗透陶瓷前、后牙全冠与前牙固定桥修复进行临床效果评价。结果 对45例患者186颗全冠与8个前牙固定桥的临床观察结果表明,Vita In-Ceram Alumina渗透陶瓷全冠具有良好的边缘密合性,色泽稳定,强度高,其失败率为0．01％。应用Vita In-Ceram Alumina渗透陶瓷制作的前牙固定桥,效果满意。结论 Vita In-Ceram Alumina渗透陶瓷修复是一种效果良好的全瓷修复方式。     

Fracture strength of all-ceramic lithium disilicate and porcelain-fused-to-metal bridges for molar replacement after dynamic loading

The replacement of missing posterior teeth using all-ceramic bridges remains a challenge. This study compares the fracture resistance of all-ceramic 3-unit bridges for the replacement of first molars to conventional porcelain-fused-to-metal bridges. Human premolars and molars were used to create two test groups and one control group of 16 specimens each. To simulate clinical parameters, the specimens were exposed to cyclic fatigue loading in an artificial mouth with simultaneous thermocycling. All samples were thereafter exposed to fracture strength testing. Porcelain-fused-to-metal bridges showed significantly higher fracture strengths than all-ceramic bridges. However, the fracture strength of the all-ceramic bridges was higher than peak physiological chewing forces.     

三种牙科全瓷底层材料饰瓷后相对透明率的对比测定

目的饰瓷及上釉后Vita In-Ceram 渗透氧化铝陶瓷、氧化锆陶瓷和Ivoclar Vivodent Empress Ⅱ铸瓷材料相对透明率的对比测定.方法在标准黑白背景下,采用接触式色彩色差计测定饰瓷后3种全瓷系统底层材料试样的表面光反射率并计算Yb/Yw的比值.结果饰瓷后,3种核瓷材料的相对透明率均有所下降.其相对透明率的范围从Empress Ⅱ的0.8880到氧化锆渗透陶瓷的1.00,其中以EmpressⅡ最为透明.结论 3种全瓷系统底层材料饰瓷后的相对透明率组间存在统计学显著差异.按照相对透明率数值高低的顺序排列为:Vita Alpha 饰瓷＞EmpressⅡ饰瓷(0.8 mm)＞In-Ceram氧化铝核瓷＞In-Ceram氧化锆核瓷.     

3种全瓷系统冠边缘适合性的比较(英文)

目的:比较临床常用3种全瓷系统(Kavo Everest、IPS e.max、In-Ceram alumina)冠的边缘适合性,为临床应用提供理论依据。方法:选取1颗无龋的离体前磨牙行牙体预备,其中牙合面预备2mm,颈部凹槽肩台,宽度为0.8mm,牙合聚合度为6°。双重印模法取模,每种系统分别制作10个冠修复体。然后采用双色硅橡胶印模法复制间隙模型,应用光学显微镜采集间隙图像及使用Auto CAD2006软件对其水平边缘间隙、垂直边缘间隙和绝对边缘间隙进行测量,将所得数据使用SPSS13.0软件包进行单因素方差分析。结果:3种全瓷系统制作的上颌前磨牙冠的水平边缘间隙的平均值在41.1～44.9μm,垂直边缘间隙的平均值在51.4～71.7μm,绝对边缘间隙的平均值在66.2～85.1μm。结论:本研究中,3种全瓷系统冠的绝对边缘间隙、垂直边缘间隙和水平边缘间隙均在临床可接受范围;然而,与In-Ceramalumina系统相比,IPS e.max和Kavo Everest系统制作的全瓷冠显示出较好的边缘适合性。     

Fracture resistance of all-ceramic and metal-ceramic inlays

PURPOSE: Metal-ceramic inlay designs were developed to determine if the esthetic qualities of all-ceramic inlays could be duplicated and at the same time improve their strength and stability. The objectives of this study were to: (1) compare the fracture resistance of metal-ceramic inlays with that of all-ceramic inlays; (2) determine the correlation between the degree of preparation taper and fracture resistance; and (3) determine the correlation between marginal gap width and fracture resistance. MATERIALS AND METHODS: Inlay preparations were made on 60 Dentoform teeth, with 30 teeth allocated for metal-ceramic inlays and 30 teeth for all-ceramic inlays. Each group was further subdivided into 5-, 10-, and 20-degree taper preparations. Metal-ceramic inlays were fabricated using Goldtech Bio 2000 metal and Ceramco porcelain extending to the margin, while all-ceramic inlays were made from Empress II ceramic. Marginal gap widths were measured at six critical areas after fabrication. The load at failure was measured using an Instron Universal Testing Machine. RESULTS: The mean fracture load for all-ceramic inlays and metal-ceramic inlays at 5, 10, and 20 degrees was 70+/-40 N, 48+/-37 N, 33+/-7 N, and 40+/-23 N, 29+/-22 N, and 14+/-4 N, respectively. The mean gap width was 105 microm and 126 microm for all-ceramic and metal-ceramic inlays, respectively. CONCLUSION: The mean fracture load for Empress inlays was significantly higher than that for metal-ceramic inlays. Inlays with a 5-degree taper were significantly more fracture resistant than those with a 20-degree taper. There was no relation between marginal gap width and fracture resistance.