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Accuracy Analysis of Digital Dental Model Data acquired by Dental Cone Beam Computed Tomography
Seen-Young Kang,Ji-Min Yu,Jun-Seok Lee,Ki-Sook Park,Seung-Youl Lee 한국자기학회 2020 Journal of Magnetics Vol.25 No.4
The purpose of this study is to analyze the accuracy of digital dental models acquired using cone beam computed tomography (CBCT), an electromagnetic wave method. While there are many reports comparing CBCT and intra oral scanners, there are few comparative studies on the accuracy of different digital dental models acquired using CBCT. Targeting this problem, in this study, we tried to analyze the accuracy of dental prosthesis data generated by different CBCT models with 3D computer programs. To this end, a single preparation dental model, 3-unit bridge dental model, and full dental model were selected and photographed using CBCT to obtain a DICOM file, which was later converted into an STL file. The converted STL file was analyzed qualitatively and quantitatively for trueness and precision using a 3D superimposition program. Although there were statistically significant differences in the trueness values of the three digital dental models (P < 0.05), no significant differences could be observed in the precision values (P > 0.05). In conclusion, using CBCT-based dental models, it may be difficult to fabricate dental prosthesis due to a distortion between the rounded part of the tooth, the prepared tooth, and adjacent teeth. However, if the accuracy of sharpness in CBCT images can be increased, in the future, this method may be employed to manufacture dental prosthesis for clinical applications.
Kang, Boram,Kim, Taikon,Kim, Mi Jung,Lee, Kyu Hoon,Choi, Seungyoung,Lee, Dong Hun,Kim, Hyo Ryoung,Jun, Byol,Park, Seen Young,Lee, Sung Jae,Park, Si-Bog Korean Academy of Rehabilitation Medicine 2015 Annals of Rehabilitation Medicine Vol.39 No.6
<P><B>Objective</B></P><P>To compare the pain-reducing effect of forest bathing alone versus forest bathing in combination with stretching and strengthening exercises in patients with chronic posterior neck pain.</P><P><B>Methods</B></P><P>Sixty-four subjects with posterior neck pain that had lasted more than 3 months were enrolled. They were randomly divided into a forest bathing alone (FBA) group and a forest bathing with exercise (FBE) group; each group included 32 subjects. All subjects from both groups walked every morning in the forest for about 2 hours for 5 days. In the afternoon, the FBE group did a stretching and strengthening exercise for about 4 hours; the FBA group had free time in the woods. Visual analog scale (VAS) on one day, VAS over the previous week, neck disability index (NDI), EuroQol 5D-3L VAS (EQ VAS) and index (EQ index), McGill pain questionnaire (MPQ), the number of trigger points in the posterior neck region (TRPs), and the range of motion of the cervical spine were evaluated on the first and last day of the program and compared between the two groups.</P><P><B>Results</B></P><P>The number of TRPs were significantly reduced in the FBE group compared with the FBA group (p=0.013). However, the other scales showed no significant difference between the two groups.</P><P><B>Conclusion</B></P><P>When patients with chronic posterior neck pain underwent a short-term forest bathing (less than 7 days) program, FBE was more effective in the reduction of the number of TRPs than FBA. However, all other pain measurement scales we evaluated showed no statistically significant difference between the two protocols.</P>
Seen-Young Kang,Ha-Na Lee,Ji-Hwan Kim,Woong-Chul Kim 대한치과보철학회 2018 The Journal of Advanced Prosthodontics Vol.10 No.5
PURPOSE. The purpose of this study was to evaluate the marginal discrepancy of heat-pressed ceramic veneers manufactured using a CAD/CAM system. MATERIALS AND METHODS. The ceramic veneers for the abutment of a maxillary left central incisor were designed using a CAD/CAM software program. Ten veneers using a microstereolithography apparatus (AM group), ten veneers using a five-axis milling machine (SM group), and ten veneers using a traditional free-hand wax technique (TW group) were prepared according to the respective manufacturing method. The ceramic veneers were also fabricated using a heat-press technique, and a silicone replica was used to measure their marginal discrepancy. The marginal discrepancies were measured using a digital microscope (×160 magnification). The data were analyzed using a nonparametric Kruskal-Wallis H test. Finally, post-hoc comparisons were conducted using Bonferroni-corrected Mann-Whitney U tests (α=.05). RESULTS. The mean켚D of the total marginal discrepancy was 99.68±28.01 μm for the AM group, 76.60±28.76 μm for the SM group, and 83.08±39.74 μm for the TW group. There were significant differences in the total marginal discrepancies of the ceramic veneers (P<.05). CONCLUSION. The SM group showed a better fit than the AM and TW groups. However, all values were within the clinical tolerance. Therefore, CAD/CAM manufacturing methods can replace the traditional free-hand wax technique.
Accuracy of provisional crowns made using stereolithography apparatus and subtractive technique
Seen-Young Kang,Jung-Hyun Park,Ji-Hwan Kim,Woong-Chul Kim 대한치과보철학회 2018 The Journal of Advanced Prosthodontics Vol.10 No.5
PURPOSE. To compare and analyze trueness and precision of provisional crowns made using stereolithography apparatus and subtractive technology. MATERIALS AND METHODS. Digital impressions were made using a master model and an intraoral scanner and the crowns were designed with CAD software; in total, 22 crowns were produced. After superimposing CAD design data and scan data using a 3D program, quantitative and qualitative data were obtained for analysis of trueness and precision. Statistical analysis was performed using normality test combined with Levene test for equal variance analysis and independent sample t-test. Type 1 error was set at 0.05. RESULTS. Trueness for the outer and inner surfaces of the SLA crown (SLAC) were 49.6±9.3 μm and 22.5±5.1 μm, respectively, and those of the subtractive crown (SUBC) were 31.8±7.5 μm and 14.6±1.2 μm, respectively. Precision values for the outer and inner surfaces of the SLAC were 18.7±6.2 μm and 26.9±8.5 μm, and those of the SUBC were 25.4±3.1 μm and 13.8±0.6 μm, respectively. Trueness values for the outer and inner surfaces of the SLAC and SUBC showed statistically significant differences (P<.001). Precision for the inner surface showed significance (P<.03), whereas that for the outer surface showed no significance (P<.58). CONCLUSION. The study demonstrates that provisional crowns produced by subtractive technology are superior to crowns fabricated by stereolithography in terms of accuracy.
A Study on Performance Evaluation of Magnetic Dental Attachments
Seen-Young Kang,Ji-Min Yu,Hyoung-Sik Kim,Ki-Sook Park,Seung-Youl Lee 한국자기학회 2019 Journal of Magnetics Vol.24 No.4
This study measures retentive force as function of the diameter, the cross-head speed, and the number of detachments of dental magnetic attachments in a clinical environment, and analyzes the validity of the international standard method for testing them. In this study, tests 1, 2, and 3 were used to measure the retentive force as a function of the contact area of the magnetic attachment, and tests 2 and 4 as a function of the cross-head speed. Test 2 and 5 compared function of the retentive force as a function of repeated detachments Results showed that the retentive force increases as the sample surface increases, and decreases as the cross head speed increases. Additionally, after 1500 detachment cycles, the retentive force increased. Finally, the international standard test method was validated, because an objective method for testing magnetic attachments in clinical environment could not be found.
Maximization of sodium storage capacity of pure carbon material used in sodium-ion batteries
Kang, Jun,Kim, Dae-Yeong,Chae, Seen-Ae,Saito, Nagahiro,Choi, Si-Young,Kim, Kwang-Ho The Royal Society of Chemistry 2019 Journal of Materials Chemistry A Vol.7 No.27
<P>Generally, carbon anode materials used in sodium-ion batteries do not exhibit good electrochemical performance because of low coulombic efficiency (CE). This paper presents a strategy to overcome this limitation by causing a co-intercalation reaction in a newly designed material. Here, Na was doped inside carbons and desodiation was caused by cleaning the doped Na. Consequently, the CE consistently exceeded 100%. Furthermore, new spaces were created when the doped Na was released continuously from the carbons, thereby allowing more Na to be stored in these spaces. This consistently increased the reversible capacity during cycling. Even though the designed material was a nanomaterial with a large specific surface area, the CE in the first cycle was 85%. Because of the co-intercalation reaction, a solid-electrolyte interphase (SEI) layer might not be formed depending on the anode surface structure and continuous long-term stable cycling was possible even without an SEI layer. Thus, a useful material for sodium-ion batteries can be designed using only carbons and without next-generation materials.</P>