• The Journal of Korean Academy of Prosthodontics
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• v.55 no.4
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• pp.372-380
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• 2017

This study was conducted to compare the marginal and internal fit of all ceramic crown using the replica technique and the triple-scan protocol. Materials and methods: Twenty zirconia ceramic crowns were fabricated using titanium abutment model. All crowns were divided into two groups of 10 each, depending on the replica technique and the triple-scan protocol. The internal and marginal fit of 10 zirconia ceramic crowns were measured at 17 points for each specimen using the replica technique. The other 10 ceramic crowns were measured using the triple-scan protocol. Statistical analysis was performed by t-test (${\alpha}=.05$). Results: The mean and standard deviation of marginal and internal fit were significantly different between the replica technique ($49.86{\pm}29.69{\mu}m$) and triple-scan protocol ($75.35{\pm}64.73{\mu}m$, P<.001). The mean and standard deviation of internal fit except marginal fit were $58.38{\pm}31.77{\mu}m$ and $64.00{\pm}46.43{\mu}m$, respectively (P>.343). Conclusion: There was a statistically significant difference in the marginal fit measured by the two methods. However, there was no statistically significant difference in the internal fit between the two methods.

• The Journal of Korean Academy of Prosthodontics
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• v.57 no.4
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• pp.321-327
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• 2019

Purpose: To evaluate an effect of additional firing process after sintering of monolithic zirconia crown on marginal and internal fit through three-dimensional analysis. Materials and methods: Ten monolithic zirconia crowns were fabricated using titanium abutment model. Monolithic zirconia crowns were designed, milled, and sintered as a control group, and additional firing with coloring was performed as a test group. Three dimensional analysis were performed by using triple-scan protocol, and cross-section analysis on mesio-distal and disto-lingual section was evaluated to measure marginal and internal fitness. Then, three-dimensional surface difference on between two groups was evaluated (${\alpha}=.05$). Results: There was statistically significant difference between the control group ($32.0{\pm}24.3{\mu}m$) and the test group ($17.0{\pm}10.8{\mu}m$) in the mesial axial wall (P < .02) and the control group ($60.2{\pm}24.3{\mu}m$) and the test group ($71.8{\pm}21.5{\mu}m$) in the distal axial wall (P < .01). There was no statistically significant difference at the remaining point. Conclusion: There was no statistical significance on the deviation of inner surface of crown according to firing number, and the results of both group were considered clinically acceptable.

• The Journal of Advanced Prosthodontics
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• v.10 no.2
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• pp.128-131
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• 2018

PURPOSE. This study aimed to evaluate the marginal discrepancy of full-arch frameworks in implant-supported prostheses fabricated using pre-sintered soft alloy (PSA). MATERIALS AND METHODS. Full-arch metal frameworks were fabricated on the edentulous implant model using casting alloy (CA), fully-sintered hard alloy (FHA), and PSA (n = 4 in each group). To evaluate the misfit of the framework to the abutments, the absolute marginal discrepancy (AMD) values of the frameworks were measured in cross-sectional images that had been drawn as part of the triple-scan protocol. The AMD values were compared among the tested alloy groups using the Kruskal-Wallis test, with a post hoc Mann-Whitney U test (${\alpha}=.05$). RESULTS. The FHA and PSA groups showed lower marginal discrepancies than the CA group (P<.001). However, the FHA group did not differ significantly from the PSA group. CONCLUSION. Soft alloy milling is comparable to hard alloy milling, and it is more precise than casting in terms of the marginal fit of implant-supported, full-arch prostheses.

• The Korean Journal of Nuclear Medicine Technology
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• v.13 no.1
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• pp.57-62
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• 2009

Purpose: Brain SPECT study is more sensitive to motion than other studies. Especially, when applying 1-day subtraction method for Diamox SPECT, it needs shorter study time in order to prevent reexamination. We were required to have new study condition and analysing method on dual detector system because triple head camera in Seoul National University Hospital is to be disposed. So we have tried to increase image quality and make the dual and triple head to have equivalent study time by using a new analysing program. Materials and Methods: Using IEC phantom, we estimated contrast, SNR and FWHM. In Hoffman 3D brain phantom which is similar with real brain, we were on the supposition that 5% of injected doses were distributed in brain tissue. To compare with existing FBP method, we used fan-beam collimator. And we applied 15 sec, 25 sec/frame for each SEPCT studies using LEHR and LEUHR. We used OSEM2D and Onco-flash3D reconstruction method and compared reconstruction methods between applied Gaussian post-filtering 5mm and not applied as well. Attenuation correction was applied by manual method. And we did Brain SPECT to patient injected 15 mCi of $^{99m}Tc$-HMPAO according to results of Phantom study. Lastly, technologist, MD, PhD estimated the results. Results: The study shows that reconstruction method by Flash3D is better than exiting FBP and OSEM2D when studied using IEC phantom. Flowing by estimation, when using Flash3D, both of 15 sec and 25 sec are needed postfiltering 5 mm. And 8 times are proper for subset 8 iteration in Flash3D. OSEM2D needs post-filtering. And it is proper that subset 4, iteration 8 times for 15sec and subset 8, iteration 12 times for 25sec. The study regarding to injected doses for a patient and study time, combination of input parameter-15 sec/frame, LEHR collimator, analysing program-Flash3D, subset 8, iteration 8times and Gaussian post-filtering 5mm is the most appropriate. On the other hands, it was not appropriate to apply LEUHR collimator to 1-day subtraction method of Diamox study because of lower sensitivity. Conclusions: We could prove that there was also an advantage of short study time effectiveness in Dual camera same as Triple gamma camera and get great result of alternation from existing fan-beam collimator to parallel collimator. In addition, resolution and contrast of new method was better than FBP method. And it could improve sensitivity and accuracy of image because lesser subjectivity was input than Metz filter of FBP. We expect better image quality and shorter study time of Brain SPECT on Dual detector system.

• The Journal of Korean Academy of Prosthodontics
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• v.58 no.1
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• pp.7-13
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• 2020

Purpose: This study was to evaluate marginal and internal discrepancy of 3-unit fixed dental prostheses (FDP) fabricated by subtractive manufacturing and additive manufacturing. Materials and methods: 3-unit bridge abutments without the maxillary left second premolar were prepared (reference model) and the reference model scan data was obtained using an intraoral scanner. 3-unit fixed dental prostheses were fabricated in the following three ways: Milled 3-unit FDP (MIL), digital light processing (DLP) 3D printed 3-unit FDP (D3P), stereolithography apparatus (SLA) 3D printed 3-unit FDP (S3P). To evaluate the marginal/internal discrepancy and precision of the prosthesis, scan data were superimposed by the triple-scan protocol and the combinations calculator, respectively. Quantitative and qualitative analysis was performed using root mean square (RMS) value and color difference map in 3D analysis program (Geomagic control X). Statistical analysis was performed using the Kruskal-Wallis test (α=.05), MannWhitney U test and Bonferroni correction (α=.05/3=.017). Results: The marginal discrepancy of S3P group was superior to MIL and D3P groups, and MIL and D3P groups were similar. The D3P and S3P groups showed better internal discrepancy than the MIL group, and there was no significant difference between the D3P and S3P groups. The precision was excellent in the order of MIL, S3P, and D3P groups. Conclusion: Within the limitation of this study, the 3-unit fixed dental prostheses fabricated by additive manufacturing showed better marginal and internal discrepancy than the those of fabricated by subtractive manufacturing, but the precision was poor.

• Journal of Technologic Dentistry
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• v.41 no.2
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• pp.63-69
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• 2019

Purpose: The purpose of this study is to evaluate the effect of CAD/CAM system milling tool wear on the marginal and internal fit of PMMA implant interim prosthesis three-dimensional manner. Methods: A total of 20 crowns were fabricated with CAD/CAM method. Their designs were unified to first molar of the left maxilla. The Customized abutments were prepared and scanned with on optical model scanner. Five crowns were milled by the newly replaced tool (1st milling), and 15 crowns were milled by 2nd, 3rd, 4th milling tool. The marginal and internal fit of 20 interim crowns were measured using the triple-scan protocol. Results: Statistically significant difference was found between the $1^{st}$ milling group ($51.8{\pm}14.6{\mu}m$) and the $3^{rd}$, $4^{th}$ milling group ($128.6{\pm}43.8{\mu}m$, $146.2{\pm}38.1{\mu}m$, respectively) at the distal margins. In the mesial margins, There was a statistically significant difference between the $1^{st}$ milling group ($63.6{\pm}25.9{\mu}m$) and the $3^{rd}$, $4^{th}$ milling group ($137.2{\pm}25.9{\mu}m$, $186.8{\pm}70.6{\mu}m$, respectively). In the distal line angle, significant difference was found between the $1^{st}$, $2^{nd}$, $3^{rd}$ milling groups and the $4^{th}$ milling group. In the mesial axial wall, significant difference was found between the $1^{st}$ milling group ($52.2{\pm}20.3{\mu}m$) and the $3^{rd}$, $4^{th}$ milling groups ($22.8{\pm}8.8{\mu}m$, $7.8{\pm}5.7{\mu}m$). Conclusion: As a result of the experiment, decrease of the marginal and internal fit was statistically significant as the number of machining cycles increased. In order to produce clinically excellent restorations, it is recommandable to consider the condition of the milling tool wear, when designing the restoration with CAD program.

• The Korean Journal of Nuclear Medicine Technology
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• v.15 no.2
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• pp.30-35
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• 2011

Purpose: The Boramae Hospital are currently using Wide beam reconstruction (WBR: UltraSPECT, Israel) to improve the resolution. The Xact-bone belongs to the WBR. It has been reported that Xact-bone helps us to improve image resolution and contrast. This study will be evaluated clinical usefulness of Xact-bone method. Materials and Methods: The usefulness evaluation of Xact-bone method was analyzed in resolution test and contrast ratio. The resolution test in Planar image were obtained from Full width at half maximum (FWHM) by using capillary tube. And the contrast ratio was obtained from Bone and Soft tissue (B/S) ratio values that were acquired from bone scan study of 50 patients before and after using the Xact-bone method. We prepared the Triple Line Source Phantom, NEMA IEC Body Phantom and Standard Jaszczak Phantom to acquire the FWHM and Contrast Ratio values of Single photon emission computed tomography (SPECT) image. Subsequently we compared among the Filtered backprojection (FBP), Orderd subset expectation maximization (OSEM) and Xact-Bone image. Results: The results of the planar Xact-bone data improved resolution about 20% by using capillary tube. In addition it was improved B/S ratio about 15%. When using Triple Line Source Phantom, SPECT Xact-bone data improved resolution for both FBP, OSEM methods about 20% and 10%, respectively. Contrast ratio in each spheres has also been increased for both methods that using NEMA IEC body Phantom and Standard Jaszczak Phantom. Conclusion: When we were using Xact-bone method, we could see to improve the resolution and Contrast ratio as compared to do not use the Xact-bone method. Accordingly, by using WBR's Xact-bone method is expected to improve the image quality. However, when introducing new software, it is needed to match the characteristics of the hospital protocol and clinical application.