• The Journal of Advanced Prosthodontics
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• v.9 no.4
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• pp.239-243
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• 2017

PURPOSE. The purpose of this study is to compare single and three-unit metal frameworks that are produced by micro-stereolithography. MATERIALS AND METHODS. Silicone impressions of a selected molar and a premolar were used to make master abutments that were scanned into a stereolithography file. The file was processed with computer aided design software to create single and three-unit designs from which resin frameworks were created using micro-stereolithography. These resin frameworks were subjected to investment, burnout, and casting to fabricate single and three-unit metal ones that were measured under a digital microscope by using the silicone replica technique. The measurements were verified by means of the Mann-Whitney U test (${\alpha}=.05$). RESULTS. The marginal gap was $101.9{\pm}53.4{\mu}m$ for SM group and $104.3{\pm}62.9{\mu}m$ for TUM group. The measurement of non-pontics in a single metal framework was $93.6{\pm}43.9{\mu}m$, and that of non-pontics in a three-unit metal framework was $64.9{\pm}46.5{\mu}m$. The dimension of pontics in a single metal framework was $110.2{\pm}61.4{\mu}m$, and that of pontics in a three-unit metal framework was $143.7{\pm}51.8{\mu}m$. CONCLUSION. The marginal gap was smaller for the single metal framework than for the three-unit one, which requires further improvement before it can be used for clinical purposes.

• The Journal of Advanced Prosthodontics
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• v.10 no.5
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• pp.367-373
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• 2018

PURPOSE. To evaluate the fit of a crown produced based on a 3D printed model and to investigate its clinical applicability. MATERIALS AND METHODS. A master die was fabricated with epoxy. Stone dies were fabricated from conventional impressions (Conventional stone die group: CS, n=10). Digital virtual dies were fabricated by making digital impressions (Digital Virtual die group: VD, n=10). 3D data obtained from the digital impression was used to fabricate 3D printed models (DLP die group: DD, n=10, PolyJet die group: PD, n=10). A total of 40 crowns were fabricated with a milling machine, based on CS, VD, DD and PD. The inner surface of all crowns was superimposed with the master die files by the "Best-fit alignment" method using the analysis software. One-way and 2-way ANOVA were performed to identify significant differences among the groups and areas and their interactive effects (${\alpha}=.05$). Tukey's HSD was used for post-hoc analysis. RESULTS. One-way ANOVA results revealed a significantly higher RMS value in the 3D printed models (DD and PD) than in the CS and DV. The RMS values of PD were the largest among the four groups. Statistically significant differences among groups (P<.001) and between areas (P<.001) were further revealed by 2-way ANOVA. CONCLUSION. Although the fit of crowns fabricated based on the 3D printed models (DD and PD) was inferior to that of crowns prepared with CS and DV, the values of all four groups were within the clinically acceptable range (<$120{\mu}m$).

• Applied Chemistry for Engineering
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• v.16 no.4
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• pp.549-555
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• 2005

To evaluate the posterior and anterior restoration of polymeric dental restorative composite (PDRC), PDRC was prepared using a silica filler treated by heat at various temperatures. Compressive strength (CS) and diametral tensile strength (DTS) values were investigated to study the effect of a heat-treated silica on the mechanical properties of PDRC using the recommended dental specifications. Both the particle size and specific volume of silica were decreased upon increasing the heat treatment temperature. CS and DTS values of PDRC containing a heat-treated silica showed 1.2 and 1.3 times, respectively, higher than that of the PDRC containing a neat silica. Also, it was found that the lower heat treatment temperature, the better mechanical properties of PDRC were observed because there was less agglomeration between silica particles. Specially, PDRC using a silica treated at $600^{\circ}C$ showed superior mechanical strength.

• Journal of dental hygiene science
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• v.15 no.3
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• pp.301-307
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• 2015

The purpose of this study was to examine factors related to the satisfaction of dental service in college women. This survey was conducted between March 14, 2014 and April 21, 2014 to investigate the influence on dental care satisfaction in college women. Data were obtained from 412 college women of some areas. At the conclusion of this investigation, as for the correlation analysis between variables affecting college women satisfaction, every variables showed significantly positive relation, and the relation between satisfaction of dental hygienist and satisfaction of hospital environment had the strongest positive relation (p<0.01). To increase the satisfaction in dental clinic, it is necessary to provide the continuing education programs for dental service to dental clinic worker.

• The Journal of the Korean dental association
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• v.41 no.2 s.405
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• pp.76-81
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• 2003

• The Journal of the Korean dental association
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• v.38 no.4 s.371
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• pp.342-349
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• 2000

• Journal of environmental and Sanitary engineering
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• v.21 no.4 s.62
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• pp.1-10
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• 2006

This research is based on self-filling survey which 220 dental hygienists who work in seoul participated on July 2006 through August 2006. This survey was analyzed the experience item and occurred time of the symptoms and the time of acute and vanish of the symptoms that dental office's working environment effects on physical subjective symptom. We suggest a plan to minimizing physical subjective symptom for health manage of dental hygienist. We found out the fact that dental hygienists were unsatisfied with hospital air condition and this polluted air condition cause them physical subjective symptom in work place. As follows analyzed results ventilation time is below the 3-times a day, this may be have some trouble in indoor air quality. The experience the symptoms level is higher then non-experience level in "Fatigue and sleepiness", "Dorsalgia, omarthralgia, cervicodynia", "Hypersensitivity", "Dry eye, itch, smarting", "Headaches" and a subjective symptom is occurred at after 11:00(am) more then 60%, 50% of the dental hygienist. This experience the symptom' pain is vanished after the work and reduced when go out the office and building, respectively. The ratio of the experience the symptoms and starting time the symptoms is anywhere from 12 noon to 4 pm (73.2%) in a day. The time of acute pain the symptoms is anywhere from 12 noon to 4 pm (78.7%) refer to the individual characteristics and work environment.

• Proceedings of the KOSOMBE Conference
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• v.1998 no.11
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• pp.253-254
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• 1998

The standardization of the dental chart proposed to computerization of the dental hospital information. To objective standardization, we gathered the dental chart from four university hospital(seoul, yonsei, kyunghee, pusan) and held a conference with dental physicians. From gathered charts, we classified the common and non-common items. We proposed the standardization to choose the most of the common items and necessary non-common things. The proposed chart include those items and the new things which the dental physicians want. After this paper, we will hold a conference with more dental physicians about more data to make more useful proposal.

• Current Optics and Photonics
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• v.7 no.3
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• pp.283-296
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• 2023

An intraoral spectral domain optical coherence tomography (SD-OCT) system has been developed, using a custom-built hand-held scanner and spectrometer. The hand-held OCT probe, based on a microelectromechanical systems scanner and a self-built miniaturized drive circuit, had a field of view sufficient for dental diagnosis. The spectrometer using a fabricated f-theta lens provided the image depth required for dental diagnosis. The axial and transverse resolutions of the OCT system in air were 7.5 ㎛ and 12 ㎛ respectively. The hand-held probe could scan an area of 10 × 10 mm², and the spectrometer could image along a depth of 2.5 mm. To verify the utility of the developed OCT system, OCT images of tooth hard and soft tissues were acquired, and a user-interface program for diagnosis was developed. Early caries and microcracks that were difficult to diagnose with existing methods could be found, and the state of restoration could be observed. Measuring the depth of the gingival sulcus, distinguishing subgingival calculus, and detecting an implant under the gingiva suggested the possibility of the SD-OCT system as a diagnostic for dental soft tissues. Through the presented OCT images, the capability of the developed SD-OCT system for dental diagnosis was demonstrated.

• Journal of Korean society of Dental Hygiene
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• v.12 no.6
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• pp.1082-1089
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• 2012

Objectives : The aim of this study was to determine the accuracy of digitized stone models, impression materials compared to the master model and the reliability of the computer aided analysis. Methods : A master model(500B-1, Nissin dental product, Japan) with the prepared lower full arch tooth was used. Ten vinyl polysiloxane impressions(Examix$^{(R)}$, GC Industrial Corp, Japan) of master model were taken and type IV stone(aesthetic-base gold$^{(R)}$, Dentona, Germany) were poured in stone models. The linear distance between the reference points were measured and analyzed on the Delcam Copycad$^{(R)}$(Delcam plc, UK). The t-student test for paired samples was used for statistical analysis. Results : The mean differences to master model for stone model and impression material were 0.11~0.19mm, and 0.19~0.29mm, respectively. There were statistical differences in dimensional accuracy for full arch impression between master model and stone model/impressions(p<.05). Conclusions : Two different scanning methods showed clinically acceptable accuracy of full arch digital impression produced by them. These results will have to be confirmed in further clinical studies.