Fracture resistance and marginal fidelity of zirconia crown according to the coping design and the cement type / 대한치과보철학회지

PURPOSE: The purpose was to compare the marginal fidelity and the fracture resistance of the zirconia crowns according to the various coping designs with different thicknesses and cement types. Material and METHODS: Zirconia copings were designed and fabricated with various thicknesses using the CAD/CAM system (Everest, KaVo Dental GmbH, Biberach., Germany). Eighty zirconia copings were divided into 4 groups (Group I: even 0.3 mm thickness, Group II: 0.3 mm thickness on the buccal surface and the buccal half of occlusal surface and the 0.6 mm thickness on the lingual surface and the lingual half of occlusal surface, Group III: even 0.6 mm thickness, Group IV: 0.6 mm thickness on the buccal surface and the buccal half of occlusal surface and the 1.0 mm thickness on the lingual surface and the lingual half of occlusal surface) of 20. By using a putty index, zirconia crowns with the same size and contour were fabricated. Each group was divided into two subgroups by type of cement: Cavitec(R) (Kerr Co, USA) and Panavia-F(R) (Kuraray Medical Inc, Japan). After the cementation of the crowns with a static load compressor, the marginal fidelity of the zirconia crowns were measured at margins on the buccal, lingual, mesial and distal surfaces, using a microscope of microhardness tester (Matsuzawa, MXT-70, Japan, x100). The fracture resistance of each crown was measured using a universal testing machine (Z020, Zwick, Germany) at a crosshead speed of 1 mm/min. The results were analyzed statistically by the two-way ANOVA and oneway ANOVA and Duncan's multiple range test at alpha= .05. RESULTS: Group I and III showed the smallest marginal fidelity, while group II demonstrated the largest value in Cavitec(R) subgroup (P .05). Panavia-F(R) subgroup showed significantly higher fracture resistance than Cavitec(R) subgroup in group I and II (P < .05). CONCLUSION: Within the limitation of this study, considering fracture resistance or marginal fidelity and esthetics, a functional ceramic substructure design of the coping with slim visible surface can be used for esthetic purposes, or a thick invisible surface to support the veneering ceramic can be used depending on the priority.

The marginal fidelity of Procera(R) AllCeram alumina copings and crowns of patients / 대한치과보철학회지

STATEMENT OF PROBLEM: Use of all-ceramic prostheses fabricated with CAD/CAM systems is increasing in the dentistry. Marginal fidelity in production of all-ceramic restoration has important clinical implications and is a key consideration issue in CAD/CAM production as well. PURPOSE: The objective of this study was to analyse marginal fidelities of Procera(R) Allceram Crown. MATERIAL AND METHODS: On 56 patients treated with Procera(R) system Allceram Crown at Dankook Dental Hospital, marginal discrepancies of 101 abutments were measured by stereomicroscope at coping and final restoration stages. Paired t-test and one-way analysis of variance on marginal discrepancy data were conducted to determine the presence of significant differences between measurement and measuring point stages. RESULTS: Marginal discrepancies of final restoration (45.82 +/- 30.84 micrometer) were lower than alumina coping (53.84 +/- 38.83 micrometer). Furthermore, the differences were found to be statistically significant at 95% confidence level. Anterior marginal discrepancies were lower than posterior marginal discrepancies, but they were not statistically significant. Lingual marginal discrepancies were higher than other measurement sites, and the differences were found to be statistically significant at 95% confidence level. CONCLUSION: Within the conditions of this study, marginal fidelities of Procera(R) Allceram Crown were acceptable, and after porcelain build-up, marginal fitness improved over alumina coping. More careful scanning is needed for better results.

A study on the marginal fidelity and the fracture strength of ceromers / 대한치과보철학회지

STATEMENT OF PROBLEM: The use of Ceromer is increasing in dentistry. But, the research of Ceromer has not been conducted much. Purpose: This study was to evaluate the marginal fidelity and internal adaptation according to marginal position. MATERIALS AND METHODS: In this study 60 resin crowns were fabricated. The measurements of the marginal fidelity were carried out using stereomicroscope SZ-40(R)(Olympus, Japan) and the measurements of fracture strength were done using Instron 8871(R)(Instron Co., U.S.A.) at a cross head speed of 1mm/min. All of the measurements were statistically analyzed by ANOVA test, multiple range test and Weibull analysis. Statistical significance was set in advance at the probability level of less than 0.05. All of the measurements were analyzed with Window SPSS(R) Version 10.0 soft ware for the personal computer. RESULTS: 1. There were no statistical differences of the marginal fidelity between Targis(R) and Tescera(R), but difference between these two and BelleGlass(R) according to materials. 2. There were no statistical differences of the marginal fidelity between no fiber group and fiber group. There were no interactions between each maerial and with/without fiber group in the marginal fidelity. 3. There were statistical differences of the fracture strength between Tescera. and BelleGlass(R), but no statistical differences of the fracture strength between Targis(R) and Tescera(R), Targis(R) and BelleGlass(R) according to materials. 4. There were statistical differences of the fracture strength between no fiber group and fiber group. There were no interactions between each material and with/without fiber group in the fracture strength. 5. When comparing the fracture surface, no fiber group showed the resin which were fractured at the labial surface and separated from the adhesion surface. In fiber group, the fractures took a place in resin compartments. CONCLUSION: The marginal fidelity and the fracture strength were clinically acceptable. From these results, Targis(R) and Tescera(R) were superior than BelleGlass(R) in the marginal fidelity. But, when applying these resin crowns in clinic, more careful consideration is needed and further study is recommended.

On the marginal fidelity of all-ceramic core using CAD/CAM system / 대한치과보철학회지

Novel methods producing supplementary and prosthetic material by cutting or discharge processing via computer design have been proposed as alternatives for traditional casting methods and are being utilized for commercial purposes. The CAD/CAM system used in dentistry can be classified into three-dimensional input of target values, restoration design, and material processing. The marginal fidelity in production of In-Ceram core has important clinical implications and is a key consideration issue in CAD/CAM production as well. Through this research, the author arrived at the following conclusion after conducting comparison analysis of marginal fidelities between the In-Ceram core produced via CAD/CAM and that produced through the traditional method: 1. In the cases of mesial, distal, and lingual margins, the core margins via CAD/CAM produced lower values than those via the traditional method, but the differences were found to be statistically insignificant. 2. In the case of labial flange, the core margins via CAD/CAM produced lower values than those via the traditional method and the differences were found to be statistically significant. (p<0.05) 3. In comparision with overall marginal fidelity, the core margins via CAD/CAM produced lower values than those via the traditional method, but the differences were found to be statistically insignificant. 4. Among the core margins produced via the traditional method did not have statistically significant differences but for those produced via CAD/CAM had statistically significant differences between labial and lingual sides and between labial and mesial sides. (p<0.05)