• 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.

• Journal of IKEEE
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• v.20 no.2
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• pp.167-170
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• 2016

Replica bit-line technique is used for making enable signal of sense amplifier which accurately tracks bit-line of SRAM. However, threshold voltage variation in the replica bit-line circuit changes the cell current, which results in variation of the sense amplifier enable time, $T_{SAE}$. The variation of $T_{SAE}$ makes the sensing operation unstable. In this paper, in addition to conventional replica bit-line delay ($RBL_{conv}$), dual replica bit-line delay (DRBD) and multi-stage dual replica bit-line delay (MDRBD) which are used for reducing $T_{SAE}$ variation are briefly introduced, and the maximum possible number of on-cell which can satisfy $6{\sigma}$ sensing yield is determined through simulation at a supply voltage of 0.6V with 14nm FinFET technology. As a result, it is observed that performance of DRBD and MDRBD is improved 24.4% and 48.3% than $RBL_{conv}$ and energy consumption is reduced which 8% and 32.4% than $RBL_{conv}$.

• The Journal of Advanced Prosthodontics
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• v.9 no.5
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• pp.358-363
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• 2017

PURPOSE. The purpose of this study was to evaluate the reliability of computer-aided replica technique (CART) by calculating its agreement with the replica technique (RT), using statistical agreement analysis. MATERIALS AND METHODS. A prepared metal die and a metal crown were fabricated. The gap between the restoration and abutment was replicated using silicone indicator paste (n = 25). Gap measurements differed in the control (RT) and experimental (CART) groups. In the RT group, the silicone replica was manually sectioned, and the marginal and occlusal gaps were measured using a microscope. In the CART group, the gap was digitized using optical scanning and image superimposition, and the gaps were measured using a software program. The agreement between the measurement techniques was evaluated by using the 95% Bland-Altman limits of agreement and concordance correlation coefficients (CCC). The least acceptable CCC was 0.90. RESULTS. The RT and CART groups showed linear association, with a strong positive correlation in gap measurements, but without significant differences. The 95% limits of agreement between the paired gap measurements were 3.84% and 7.08% of the mean. The lower 95% confidence limits of CCC were 0.9676 and 0.9188 for the marginal and occlusal gap measurements, respectively, and the values were greater than the allowed limit. CONCLUSION. The CART is a reliable digital approach for evaluating the fit accuracy of fixed dental prostheses.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.371-373
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• 2005

We demonstrated a replica molding technique for producing a self-formed multidomain structure displays (LCDs). The multidomain structure was naturally obtained on a replica mold film having periodic patterns which have two dimensional microgrooves. It was found that with the axially symmetric multidomain structure along the microgrooves exhibits excellent viewing characteristics.

• Polymer(Korea)
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• v.28 no.4
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• pp.305-313
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• 2004

A vacuum pressure-difference technique for making a nano-precision replica is investigated for various applications. Master patterns for replication were fabricated using a nano-replication printing (nRP) process. In the nRP process, any picture and pattern can be replicated from a bitmap figure file in the range of several micrometers with resolution of 200nm. A liquid-state monomer is solidified by two-photon absorption (TPA) induced by a femto-second laser according to a voxel matrix scanning. After polymerization, the remaining monomers were removed simply by using ethanol droplets. And then, a gold metal layer of about 30nm thickness was deposited on the fabricated master patterns prior to polydimethylsiloxane molding for preventing bonding between the master and the polydimethylsiloxane mold. A few gold particles attached on the polydimethylsiloxane stamp during detaching process were removed by a gold selecting etchant. After fabricating the polydimethylsiloxane mold, a nano-precision polydimethylsiloxane replica was reproduced. More precise replica was produced by the vacuum pressure-difference technique that is proposed in this paper. Through this study, direct patterning on a glass plate, replicating a polydimethylsiloxane mold, and reproducing polydimethylsiloxane replica are demonstrated with a vacuum pressure-difference technique for various micro/nano-applications.

• The Journal of Korean Academy of Prosthodontics
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• v.55 no.2
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• pp.135-143
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• 2017

Purpose: This research was conducted to compare the marginal and internal fit of zirconia prostheses fabricated with the model scan method and the intraoral scan method. Materials and methods: In this study, 20 extracted human mandibular first molar was used in the preparation of abutment tooth for the fabrication of zirconia prostheses. In the first group, the model scan method was applied on 10 prepared teeth. In the other group, the intraoral scan method was used on other 10 prepared teeth. Datum of both groups were transmitted to the software system. Afterwards, 20 zirconia prostheses were fabricated using the Ceramill system. Weight technique was used to evaluate the internal gap of the zirconia prostheses. In the Replica technique, marginal gap of the zirconia prostheses were analyzed by optical microscopy. Statistical analysis was based on one-way ANOVA. Results: Model scan group showed lower average weight than intraoral scan group when weight technique was applied, which has significance (P < .05). Also, model scan group showed significantly lower figures in all 5 measurements of replica technique than intraoral scan group (P < .05). Conclusion: Zirconia prostheses of both groups demonstrated clinically acceptable margin and internal fit. However, model scanned zirconia prostheses showed higher marginal and internal fit than intraoral scanned crowns.

• Journal of Information Display
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• v.10 no.2
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• pp.68-71
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• 2009

A replica-molding method of fabricating a dual-gap substrate for transflective liquid crystal (LC) displays is demonstrated. The dual-gap substrate provides homeotropic alignment for the LC molecules without any surface treatment and embedded bilevel microstructure on one of the two surfaces to maintain different cell gaps between the transmissive and reflective subpixels. The proposed transflective LC cell shows no electro-optic disparity between two subpixels and reduces the panel thickness and weight by 30% compared to the conventional transflective LC cell, which has two glass substrates.

• The Journal of Advanced Prosthodontics
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• v.9 no.3
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• pp.159-169
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• 2017

PURPOSE. The purposes of this study were to evaluate the marginal and internal gaps, and the potential clinical applications of three different methods of dental prostheses fabrication, and to compare the prostheses prepared using the silicone replica technique (SRT) and those prepared using the three-dimensional superimposition analysis (3DSA). MATERIALS AND METHODS. Five Pekkton, lithium disilicate, and zirconia crowns were each manufactured and tested using both the SRT and the two-dimensional section of the 3DSA. The data were analyzed with the nonparametric version of a two-way analysis of variance using rank-transformed values and the Tukey's post-hoc test (${\alpha}=.05$). RESULTS. Significant differences were observed between the fabrication methods in the marginal gap (P < .010), deep chamfer (P < .001), axial wall (P < .001), and occlusal area (P < .001). A significant difference in the occlusal area was found between the two measurement methods (P < .030), whereas no significant differences were found in the marginal gap (P > .350), deep chamfer (P > .719), and axial wall (P > .150). As the 3DSA method is three-dimensional, it allows for the measurement of arbitrary points. CONCLUSION. All of the three fabrication methods are valid for measuring clinical objectives because they produced prostheses within the clinically acceptable range. Furthermore, a three-dimensional superimposition analysis verification method such as the silicone replica technique is also applicable in clinical settings.

• The Journal of Advanced Prosthodontics
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• v.12 no.3
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• pp.173-180
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• 2020

PURPOSE. This study compared digital (reference point matching) and replica methods for measuring marginal and internal fit of full coverage restorations. MATERIALS AND METHODS. A maxillary left first molar typodent was fixed on to an aluminum base and prepared to receive all-ceramic full coverage restoration. The model was scanned with an intraoral scanner (CEREC Omnicam, Sirona, York, PA, USA). Twelve crowns were fabricated from lithium disilicate blocks (IPS emax CAD, Ivoclar Vivadent) and then crystalized. Marginal and internal fit of each restoration was measured by two examiners using replica and a new digital three-dimensional technique. Reliability between the two methods and two examiners was assessed by correlation and Cronbach's Alpha coefficient (P<.05). A Bland-Altman assessment for agreement was used to compare the two methods. RESULTS. Bland-Altman assessment showed that the mean of difference for marginal, absolute marginal, and axial gap was respectively -1.04 ㎛, -41.9 ㎛, and -29.53 ㎛ with limit of agreement (LOA) between -37.26 to 35.18 ㎛ for marginal, -105.85 to 22.05 ㎛ for absolute marginal and -80.52 to 22.02 ㎛ for axial gap. Positive correlation for repeatability (P<.05) in determining marginal and internal gaps by the two examiners in both techniques was revealed. Reliability of both techniques in all sites of measurements was at least good (0.8 ≤ α < 0.9). CONCLUSION. Both measuring techniques appeared highly reliable for evaluating fit of fixed dental restorations, while reference point matching provided higher values in axial and absolute marginal gap assessment.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.11a
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• pp.261-262
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• 2008