• The Journal of Advanced Prosthodontics
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• v.15 no.3
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• pp.155-170
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• 2023

PURPOSE. This study aims to clinically compare the fitness and trueness of zirconia crowns fabricated by different combinations of open CAD-CAM systems. MATERIALS AND METHODS. Total of 40 patients were enrolled in this study, and 9 different zirconia crowns were prepared per patient. Each crown was made through the cross-application of 3 different design software (EZIS VR, 3Shape Dental System, Exocad) with 3 different processing devices (Aegis HM, Trione Z, Motion 2). The marginal gap, absolute marginal discrepancy, internal gap(axial, line angle, occlusal) by a silicone replica technique were measured to compare the fit of the crown. The scanned inner and outer surfaces of the crowns were compared to CAD data using 3D metrology software to evaluate trueness. RESULTS. There were significant differences in the marginal gap, absolute marginal discrepancy, axial and line angle internal gap among the groups (P < .05) in the comparison of fit. There was no statistically significant difference among the groups in terms of occlusal internal gap. The trueness ranged from 36.19 to 43.78 ㎛ but there was no statistically significant difference within the groups (P > .05). CONCLUSION. All 9 groups showed clinically acceptable level of marginal gaps ranging from 74.26 to 112.20 ㎛ in terms of fit comparison. In the comparison of trueness, no significant difference within each group was spotted. Within the limitation of this study, open CAD-CAM systems used in this study can be assembled properly to fabricate zirconia crown.

• Ocean Systems Engineering
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• v.9 no.3
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• pp.287-328
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• 2019

Comprehensive understanding of the flood risk assessments via frequency analysis often demands multivariate designs under the different notations of return periods. Flood is a tri-variate random consequence, which often pointing the unreliability of univariate return period and demands for the joint dependency construction by accounting its multiple intercorrelated flood vectors i.e., flood peak, volume & durations. Selecting the most parsimonious probability functions for demonstrating univariate flood marginals distributions is often a mandatory pre-processing desire before the establishment of joint dependency. Especially under copulas methodology, which often allows the practitioner to model univariate marginals separately from their joint constructions. Parametric density approximations often hypothesized that the random samples must follow some specific or predefine probability density functions, which usually defines different estimates especially in the tail of distributions. Concentrations of the upper tail often seem interesting during flood modelling also, no evidence exhibited in favours of any fixed distributions, which often characterized through the trial and error procedure based on goodness-of-fit measures. On another side, model performance evaluations and selections of best-fitted distributions often demand precise investigations via comparing the relative sample reproducing capabilities otherwise, inconsistencies might reveal uncertainty. Also, the strength & weakness of different fitness statistics usually vary and having different extent during demonstrating gaps and dispensary among fitted distributions. In this literature, selections efforts of marginal distributions of flood variables are incorporated by employing an interactive set of parametric functions for event-based (or Block annual maxima) samples over the 50-years continuously-distributed streamflow characteristics for the Kelantan River basin at Gulliemard Bridge, Malaysia. Model fitness criteria are examined based on the degree of agreements between cumulative empirical and theoretical probabilities. Both the analytical as well as graphically visual inspections are undertaken to strengthen much decisive evidence in favour of best-fitted probability density.

• Journal of dental hygiene science
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• v.14 no.3
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• pp.349-355
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• 2014

The purpose of this study was to evaluate marginal gap of fixed dental prostheses (FDPs) fabricated by soft metal material with using dental computer aided design/computer aided manufacturing (CAD/CAM) system and to compare gap of its by a conventional method. Ten same cases of study models were manufactured and scanned for digital models fabricating. Ten FDPs were fabricated by soft metal material using dental CAD/CAM (SMB group). Then, ten FDPs were fabricated by cast metal using lost wax technique and casting method (LWC group). Marginal gap was measured by silicone replica technique. Gap was measured by digital microscope (${\times}160$). Mann-Whitney test for statistical analysis was executed (${\alpha}=0.05$). The mean (standard deviations) of marginal gap was $76.5{\mu}m$ (35.2) for the SMB group, and $82.9{\mu}m$ (22.1) for the LWC group. Statistically significant differences were not found between SMB and LWC. As results, FDPs fabricated by soft metal material were clinically acceptable range.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.10
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• pp.6611-6617
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• 2015

The purpose of this study is to compare the marginal and internal fit of metal and zirconia coping which is fabricated by manual and CAD/CAM(Computer Aided Design/Computer Aided Manufacturing). The model is prepared with Urethane material and two abutment teeth are fabricated with a knife and chamfer margin. Silicon replica technique is used to measure the marginal fit of manually fabricated and the CAD/CAM coping. Internal fitting level is measured with a microscope and the image is captured with a CCD camera. The distance between abutment teeth and coping is measured with a callibrated image analyzer software; marginal opening (MO), marginal gap (MG), internal gap (IG) at maximum curvature area, axial gap (AG), and occlusal gap (OG). Two-way ANOVA test is applied to compare fabrication technique and to analysis of abutment pattern. In addition, one-way ANOVA and Scheffe's test is used to analyze each parameter of the test. The result shows that the fit is < $120{\mu}m$ except OG of CAD/CAM and MO of knife margin. The CAD/CAM fabricated coping showed higher fit level at chamfer margin. However, knife margin showed better fitness compared to chamfer margin at MG. AG showed the minimum dimension with a constant result (< $38{\mu}m$).

• Journal of Technologic Dentistry
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• v.30 no.2
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• pp.57-63
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• 2008

Statement of problem: Conventional techniques for implant framework fabrication produce significant error that is inconsistent with passive-fit requirement for osseointegrated implants. One of the etiologic factors which cause the errors is a sprue which may deform the framework during solidification and contraction. Purpose: This study was aimed to evaluate objectively effect of the sprue design on the accuracy of fit of implant prosthesis. Materials and method: Three different designs were considered relative to effect of casting accuracy. The first design had straight sprues and a button of excess alloy at the non-casting end of the sprues. The second was runner bar design(with the button). The last was straight sprues design(without the button). Gold cylinder and laboratory analogue had been used to diminish variables affecting to casting accuracy. Gold alloy and pressure-vacuum casting machine had been used. Marginal gap had been measured by SEM. One-way ANOVA and Duncan test had been used for statistical analysis. Results: The first design showed $79.87{\pm}13.95{\mu}m$ marginal gap. The second and third were $40.17{\pm}15.8{\mu}m$ and $35.17{\pm}9.95{\mu}m$ respectively. Conclusion: Straight sprues without button and runner bar designs were more accurate than straight sprues with button design(P<.05).

• The Journal of the Korea Contents Association
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• v.10 no.6
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• pp.352-359
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• 2010

The objective of this paper is to study on the property transformation for materials and to evaluate the precision through marginal gap depending on heat-treatment of metal-porcelain by the gold electro-forming system. Specimens for evaluating property of hardness treat non-treat(HC), once(H1), twice(H2), and three times(H3) by heating, respectively. Specimens for marginal gap classified as each groups of special bonder(FS), special bonder, opaque(FO), special bonder, opaque, body(FB) and non-treatment(FC). As a result for micro-hardness test, the level of hardness on each groups of H1, H2, H3 decreased rather than HC group(p<0.05). In addition, marginal gap was not affected by the number of times being treated by heating. Therefore, the marginal fitness and the precision for mterials were not affected by the heat-treatment on the process to make GES metal-porcelain.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.5
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• pp.470-478
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• 2008

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 ($45.82{\pm}30.84\;{\mu}m$) were lower than alumina coping ($53.84{\pm}38.83\;{\mu}m$). 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.

• Journal of Dental Rehabilitation and Applied Science
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• v.30 no.1
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• pp.16-22
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• 2014

Purpose: The purpose of this study was to assess the marginal and mesial fitness of zirconia single copings and 3-unit fixed partial dentures (FPDs) manufactured with an identical model. Materials and Methods: An epoxy model in which the maxillary right 2nd premolar is lost and maxillary 1st premolar and 2nd molar are formed as abutments was manufactured and scanned by using a laser scanner. A ten units of zirconia single copings were manufactured for maxillary 1st premolar and 2nd molar, respectively and the same number of 3-unit FPDs were manufactured. For the measurements of fitness, the manufactured silicone replicas were divided into four parts and the fitness were measured by digital microscope at measurement points (P1, P2, P3, P4 and P5) of each plane. The measured gaps were classified into three categories: marginal gap (MG, P1), axial gap (AG, average of P2 and P3), occlusal gap (OG, average of P4 and P5). Results: The ranges of MG, AG and OG for single copings were 18.47 - 40.54 ${\mu}m$, 39.73 - 73.61 ${\mu}m$ and 116.90 - 134.69 ${\mu}m$, respectively. The ranges of MG, AG and OG for 3-unit FPDs were 45.95 - 87.44 ${\mu}m$, 23.78 - 57.00 ${\mu}m$ and 99.89 - 131.06 ${\mu}m$, respectively. Conclusion: The result of the study shows that the MGs for 3-unit FPDs were higher than those of single copings, though they are within the range of clinical acceptance, indicating that the use of more homogeneous zirconia block and modification of sintering processes are needed to ensure the prevention of increase of gap in 3-unit FPDs.

• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.2
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• pp.95-107
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• 2009

The purpose of this research was to examine the fitness of zirconia cores that were made by different sintering methods; generic electricity furnace and microwave furnace. Firstly, 12 cores for each group were made by using each different sintering process and attached them to a metal die with silicon. The internal and marginal gap of sintered zirconia was measured by using Skyscan 1076 micro-CT, then it was reorganized by CT-An software. To each samples, we extracted B-L image, M-D image of cutting side, and cross-sectional side of tooth long axis and calculated the mean value of marginal, axial, and occlusal gap each side. Results: 1. The mean marginal gap of sintered zirconia was $36.20{\mu}m$ for EVE, $47.67{\mu}m$ for LAV, $52.47{\mu}m$ for DEN, and $54.63{\mu}m$ for CER. 2. For the axial wall, the research showed the largest value of $63.49{\mu}m$ for EVE, but there were no statistical significance. 3. In related to the occlusal internal measurement, DEN showed the smallest value ($77.06{\mu}m$), EVE and CER showed significantly high value. From this study, it is suggested that CAD/CAM zirconia core which was made in the process of microwave sintering has clinically acceptable values in marginal and internal gap.

• The Journal of Korean Academy of Prosthodontics
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• v.58 no.4
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• pp.313-320
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• 2020

Purpose: The purpose of this study was to evaluate the machining precision and the marginal and internal fit of single restorations fabricated with three types of lithium disilicate ceramic blocks and to evaluate the correlation. Materials and methods: Single restorations were designed using a CAD software program. The crown designed model file was extracted from the CAD software program. Three types of lithium disilicate blocks (Rosetta; HASS, IPS e.max CAD; Ivoclar vivadent, VITA Suprinity; VITA) were milled using a milling machine. For the fabrication of the crown scanned model file, the intaglio surface of the restoration was digitized using a contact scanner. Then, using the three-dimensional inspection software (Geomagic control X; 3D Systems), the process of the overlap of the crown designed model and the scanned model and 3-dimensional analysis was conducted. In addition, the marginal and internal fit of the crowns was evaluated by a silicone replication method. The difference among three types of single ceramic crown was analyzed using a Kruskal-Wallis H test, and Spearman correlation analysis was performed to analyze the correlation between machining precision and fitness (α=.05). Results: There was a significant difference in the machining precision and the marginal and internal fit according to the type of ceramic block (P<.001). In addition, the machining precision and the marginal and internal fit were positively correlated (P<.001). Conclusion: The marginal fit of crowns fabricated according to the types of ceramic blocks was within the clinically acceptable range (< 120 ㎛), so it can be regarded as appropriate machining precision applicable to all clinical as aspects in terms of the marginal fit.