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Article ; Online: A paradigm shift: AMPK negatively regulates ULK1 activity.

Park, Ji-Man / Kim, Do-Hyung

2023 Volume 20, Issue 4, Page(s) 960–962

Abstract: In glucose-starved cells, macroautophagy (hereafter referred to as autophagy) is considered to serve as an energy-generating process contributing to cell survival. AMPK (adenosine monophosphate-activated protein kinase) is the primary cellular energy ... ...

Abstract	In glucose-starved cells, macroautophagy (hereafter referred to as autophagy) is considered to serve as an energy-generating process contributing to cell survival. AMPK (adenosine monophosphate-activated protein kinase) is the primary cellular energy sensor that is activated during glucose starvation. According to the current paradigm in the field, AMPK promotes autophagy in response to energy deprivation by binding and phosphorylating ULK1 (UNC-51 like kinase 1), the protein kinase responsible for autophagy initiation. However, conflicting findings have been reported casting doubts about the current established model. In our recent study, we have thoroughly reevaluated the role of AMPK in autophagy. Contrary to the current paradigm, our study revealed that AMPK functions as a negative regulator of ULK1 activity. The study has elucidated the underlying mechanism and demonstrated the significance of the negative role in controlling autophagy and maintaining cellular resilience during energy depletion.
MeSH term(s)	Autophagy-Related Protein-1 Homolog/metabolism ; Humans ; AMP-Activated Protein Kinases/metabolism ; Autophagy/physiology ; Animals ; Models, Biological ; Intracellular Signaling Peptides and Proteins
Chemical Substances	Autophagy-Related Protein-1 Homolog (EC 2.7.11.1) ; AMP-Activated Protein Kinases (EC 2.7.11.31) ; ULK1 protein, human (EC 2.7.11.1) ; Intracellular Signaling Peptides and Proteins
Language	English
Publishing date	2023-06-20
Publishing country	United States
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ZDB-ID	2454135-7
ISSN	1554-8635 ; 1554-8627
ISSN (online)	1554-8635
ISSN	1554-8627
DOI	10.1080/15548627.2023.2223465
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Article ; Online: Redefining the role of AMPK in autophagy and the energy stress response.

Park, Ji-Man / Lee, Da-Hye / Kim, Do-Hyung

Nature communications

2023 Volume 14, Issue 1, Page(s) 2994

Abstract: Autophagy maintains cellular homeostasis during low energy states. According to the current understanding, glucose-depleted cells induce autophagy through AMPK, the primary energy-sensing kinase, to acquire energy for survival. However, contrary to the ... ...

Abstract	Autophagy maintains cellular homeostasis during low energy states. According to the current understanding, glucose-depleted cells induce autophagy through AMPK, the primary energy-sensing kinase, to acquire energy for survival. However, contrary to the prevailing concept, our study demonstrates that AMPK inhibits ULK1, the kinase responsible for autophagy initiation, thereby suppressing autophagy. We found that glucose starvation suppresses amino acid starvation-induced stimulation of ULK1-Atg14-Vps34 signaling via AMPK activation. During an energy crisis caused by mitochondrial dysfunction, the LKB1-AMPK axis inhibits ULK1 activation and autophagy induction, even under amino acid starvation. Despite its inhibitory effect, AMPK protects the ULK1-associated autophagy machinery from caspase-mediated degradation during energy deficiency, preserving the cellular ability to initiate autophagy and restore homeostasis once the stress subsides. Our findings reveal that dual functions of AMPK, restraining abrupt induction of autophagy upon energy shortage while preserving essential autophagy components, are crucial to maintain cellular homeostasis and survival during energy stress.
MeSH term(s)	Humans ; Amino Acids ; AMP-Activated Protein Kinases ; Autophagy ; Caspases ; Glucose ; Cells, Cultured
Chemical Substances	Amino Acids ; AMP-Activated Protein Kinases (EC 2.7.11.31) ; Caspases (EC 3.4.22.-) ; Glucose (IY9XDZ35W2)
Language	English
Publishing date	2023-05-24
Publishing country	England
Document type	Journal Article ; Research Support, N.I.H., Extramural
ZDB-ID	2553671-0
ISSN	2041-1723 ; 2041-1723
ISSN (online)	2041-1723
ISSN	2041-1723
DOI	10.1038/s41467-023-38401-z
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Article ; Online: Deep learning-based automated detection of the dental crown finish line: An accuracy study.

Choi, Jinhyeok / Ahn, Junseong / Park, Ji-Man

The Journal of prosthetic dentistry

2023

Abstract: Statement of problem: The marginal fit of dental prostheses is a clinically significant issue, and dental computer-aided design software programs use automated methods to expedite the extraction of finish lines. The accuracy of these automated methods ... ...

Abstract	Statement of problem: The marginal fit of dental prostheses is a clinically significant issue, and dental computer-aided design software programs use automated methods to expedite the extraction of finish lines. The accuracy of these automated methods should be evaluated. Purpose: The purpose of this study was to compare the accuracy of a new hybrid method with existing software programs that extract finish lines using fully automated and semiautomated methods. Material and methods: A total of 182 jaw scans containing at least 1 natural tooth abutment were collected and divided into 2 groups depending on how the digital data were created. Group DS used desktop scanners to scan casts trimmed for improved finish line visibility, while Group IS used intraoral scans. The method from Dentbird was compared using 3 software packages from 3Shape, exocad, and MEDIT. The Hausdorff and Chamfer distances were used in this study. Three dental laboratory technicians experienced in the digital workflow evaluated clinical finish line acceptance and its Hausdorff and Chamfer distances. For statistical analysis, t tests were performed after the outliers had been removed using the Tukey interquartile range method (α=.05). Results: Outliers identified by using the Tukey interquartile range method were more numerous in the semiautomatic methods than in the automatic methods. When considering data without outliers, the software performance was found to be similar for desktop scans of the trimmed casts. However, the method from Dentbird demonstrated statistically better results (P<.05) for the posterior tooth with finish lines in concave regions than the 3Shape, exocad, and MEDIT software programs. Furthermore, thresholds coherent with clinical acceptance were determined for the Hausdorff and Chamfer distances. The Hausdorff distance threshold was 0.366 mm for desktop scans and 0.566 mm for intraoral scans. For the Chamfer distance, the threshold was 0.026 for desktop scans and 0.100 for intraoral scans. Conclusions: The method from Dentbird demonstrated a comparable or better performance than the other software solutions, particularly excelling in finish line extraction for intraoral scans. Using a hybrid method combining deep learning and computer-aided design approaches enables the robust and accurate extraction of finish lines.
Language	English
Publishing date	2023-12-13
Publishing country	United States
Document type	Journal Article
ZDB-ID	218157-5
ISSN	1097-6841 ; 0022-3913
ISSN (online)	1097-6841
ISSN	0022-3913
DOI	10.1016/j.prosdent.2023.11.018
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Article ; Online: Trueness, physical properties, and surface characteristics of additive-manufactured zirconia crown.

Cho, Su-Min / Young Kim, Ryan Jin / Park, Ji-Man / Chung, Hye-Min / Kim, Deok-Yeong

Journal of the mechanical behavior of biomedical materials

2024 Volume 154, Page(s) 106536

Abstract: Objective: This study aimed to conduct a comparison of trueness and physical and surface properties among five distinct types of additive manufactured (AM) zirconia crowns and zirconia crowns produced using the subtractive manufacturing (SM).: ... ...

Abstract	Objective: This study aimed to conduct a comparison of trueness and physical and surface properties among five distinct types of additive manufactured (AM) zirconia crowns and zirconia crowns produced using the subtractive manufacturing (SM). Material and methods: Zirconia crowns were fabricated using five distinct techniques, each varying in the method of slurry transfer and photocuring source. Each experimental group utilized either one of the four digital light processing (DLP)-based techniques (DLP spreading, DLP spreading gradation, DLP vat and DLP circular spreading) or the stereolithography (SLA)-based technique (SLA spreading). The control (CON) group employed SM. To assess accuracy, trueness was measured between the scan and reference data. To analyze the physical properties, voids were examined using high-energy spiral micro-computed tomography scans, and the crystal structure analysis was performed using X-ray diffraction (XRD). Surface roughness was assessed through laser scanning microscopy. Results: Differences in the trueness of internal surfaces of crowns were found among the groups (P < 0.05). Trueness varied across the measurement surfaces (occlusal, lateral, and marginal) in all the groups except for the DLP spreading gradation group (P < 0.05). Voids were observed in all AM groups. All groups showed similar XRD patterns. All AM groups showed significantly greater surface roughness compared to the CON group (P < 0.001). Conclusion: The AM zirconia crowns showed bubbles and a rougher surface compared to the SM crowns. All groups exhibited typical zirconia traits and trueness levels within clinically acceptable limits, suggesting that current zirconia AM techniques could be suitable for dental applications.
MeSH term(s)	Computer-Aided Design ; X-Ray Microtomography ; Crowns ; Zirconium ; Surface Properties
Chemical Substances	zirconium oxide (S38N85C5G0) ; Zirconium (C6V6S92N3C)
Language	English
Publishing date	2024-04-02
Publishing country	Netherlands
Document type	Journal Article
ZDB-ID	2378381-3
ISSN	1878-0180 ; 1751-6161
ISSN (online)	1878-0180
ISSN	1751-6161
DOI	10.1016/j.jmbbm.2024.106536
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Article: Comparative analysis on reproducibility among 5 intraoral scanners: sectional analysis according to restoration type and preparation outline form.

Park, Ji-Man

The journal of advanced prosthodontics

2016 Volume 8, Issue 5, Page(s) 354–362

Abstract: Purpose: The trueness and precision of acquired images of intraoral digital scanners could be influenced by restoration type, preparation outline form, scanning technology and the application of power. The aim of this study is to perform the comparative ...

Abstract	Purpose: The trueness and precision of acquired images of intraoral digital scanners could be influenced by restoration type, preparation outline form, scanning technology and the application of power. The aim of this study is to perform the comparative evaluation of the 3-dimensional reproducibility of intraoral scanners (IOSs). Materials and methods: The phantom containing five prepared teeth was scanned by the reference scanner (Dental Wings) and 5 test IOSs (E4D dentist, Fastscan, iTero, Trios and Zfx Intrascan). The acquired images of the scanner groups were compared with the image from the reference scanner (trueness) and within each scanner groups (precision). Statistical analysis was performed using independent two-samples t-test and analysis of variance (α=.05). Results: The average deviations of trueness and precision of Fastscan, iTero and Trios were significantly lower than the other scanners. According to the restoration type, significantly higher trueness was observed in crown and inlay than in bridge. However, no significant difference was observed among four sites of preparation outline form. If compared by the characteristics of IOS, high trueness was observed in the group adopting the active triangulation and using powder. However, there was no significant difference between the still image acquisition and video acquisition groups. Conclusion: Except for two intraoral scanners, Fastscan, iTero and Trios displayed comparable levels of trueness and precision values in tested phantom model. Difference in trueness was observed depending on the restoration type, the preparation outline form and characteristics of IOS, which should be taken into consideration when the intraoral scanning data are utilized.
Language	English
Publishing date	2016-10-21
Publishing country	Korea (South)
Document type	Journal Article
ZDB-ID	2575831-7
ISSN	2005-7814 ; 2005-7806
ISSN (online)	2005-7814
ISSN	2005-7806
DOI	10.4047/jap.2016.8.5.354
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Article ; Online: Measuring the Complete-arch Distortion of an Optical Dental Impression.

Park, Ji-Man / Shim, June-Sung

Journal of visualized experiments : JoVE

2019 , Issue 147

Abstract: Digital workflows have actively been used to produce dental restorations or oral appliances since dentists started to make digital impressions by acquiring 3D images with an intraoral scanner. Because of the nature of scanning the oral cavity in the ... ...

Abstract	Digital workflows have actively been used to produce dental restorations or oral appliances since dentists started to make digital impressions by acquiring 3D images with an intraoral scanner. Because of the nature of scanning the oral cavity in the patient's mouth, the intraoral scanner is a handheld device with a small optical window, stitching together small data to complete the entire image. During the complete-arch impression procedure, a deformation of the impression body can occur and affect the fit of the restoration or appliance. In order to measure these distortions, a master specimen was designed and produced with a metal 3D printer. Designed reference geometries allow setting independent coordinate systems for each impression and measure x, y, and z displacements of the cylinder top circle center where the distortion of the impression can be evaluated. In order to evaluate the reliability of this method, the coordinate values of the cylinder are calculated and compared between the original computer-aided design (CAD) data and the reference data acquired with the industrial scanner. The coordinate differences between the two groups were mostly less than 50 µm, but the deviations were high due to the tolerance of 3D printing in the z coordinates of the obliquely designed cylinder on the molar. However, since the printed model sets a new standard, it does not affect the results of the test evaluation. The reproducibility of the reference scanner is 11.0 ± 1.8 µm. This test method can be used to identify and improve upon the intrinsic problems of an intraoral scanner or to establish a scanning strategy by measuring the degree of distortion at each part of the complete-arch digital impression.
MeSH term(s)	Dental Arch/physiology ; Dental Impression Technique/standards ; Dental Models/standards ; Humans ; Imaging, Three-Dimensional/methods
Language	English
Publishing date	2019-05-30
Publishing country	United States
Document type	Journal Article ; Research Support, Non-U.S. Gov't ; Video-Audio Media
ZDB-ID	2259946-0
ISSN	1940-087X ; 1940-087X
ISSN (online)	1940-087X
ISSN	1940-087X
DOI	10.3791/59261
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Article ; Online: Comparative analysis of flexural strength of 3D printed and milled 4Y-TZP and 3Y-TZP zirconia.

Kyung, Kyu-Young / Park, Ji-Man / Heo, Seong-Joo / Koak, Jai-Young / Kim, Seong-Kyun / Ahn, Jin-Soo / Yi, Yuseung

The Journal of prosthetic dentistry

2024 Volume 131, Issue 3, Page(s) 529.e1–529.e9

Abstract: Statement of problem: The mechanical properties of 3 dimensionally (3D) printed zirconia have been reported to be comparable with those of milled zirconia, except for the flexural strength. However, most previous studies tested 3 mol% yttria-stabilized ... ...

Abstract	Statement of problem: The mechanical properties of 3 dimensionally (3D) printed zirconia have been reported to be comparable with those of milled zirconia, except for the flexural strength. However, most previous studies tested 3 mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP), making it necessary to study 3D printed zirconia with 4 mol% yttria content (4Y-TZP). Purpose: The purpose of this in vitro study was to compare the flexural strength of 3D printed 4Y-TZP with 3Y-TZP materials and milled 4Y-TZP. Material and methods: A total of 80 disk specimens (Ø15×1.5 mm) were fabricated and divided into 4 groups (n=20) using the fabrication method and yttria content: milled 3Y-TZP (Katana HT; Kuraray Noritake), 3D printed 3Y-TZP (TZ-3Y-E; Tosoh), milled 4Y-TZP (Katana STML; Kuraray Noritake), and 3D printed 4Y-TZP (3DMAT; Genoss). The biaxial flexural strength was determined with a piston-on-3-ball test (n=15). The flexural strength of each specimen was measured, and the Weibull modulus (m) and characteristic strength (σ Results: The flexural strength of 3D printed 4Y-TZP was significantly higher than that of milled 4Y-TZP (P<.001). In contrast, the flexural strength of 3D printed 3Y-TZP was significantly lower than that of milled 3Y-TZP (P<.001). X-ray diffraction (XRD) analysis revealed that the tetragonal phase was the dominant phase in all groups, with the identification of some cubic phase peaks. Conclusions: Three dimensionally printed 4Y-TZP showed significantly higher flexural strength than milled 4Y-TZP and exhibited a clinically acceptable flexural strength exceeding 800 MPa.
MeSH term(s)	Flexural Strength ; Microscopy, Electron, Scanning ; Printing, Three-Dimensional ; Yttrium ; Zirconium
Chemical Substances	yttria (X8071685XT) ; zirconium oxide (S38N85C5G0) ; Yttrium (58784XQC3Y) ; Zirconium (C6V6S92N3C)
Language	English
Publishing date	2024-01-11
Publishing country	United States
Document type	Journal Article
ZDB-ID	218157-5
ISSN	1097-6841 ; 0022-3913
ISSN (online)	1097-6841
ISSN	0022-3913
DOI	10.1016/j.prosdent.2023.12.020
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Article ; Online: Influence of crown shade, translucency, and scan powder application on the trueness of intraoral scanners.

Hlaing, Nan Hsu Myat Mon / Lee, Hyeonjong / Jeong, Yuwon / Park, Ji-Man / Lee, Sang J / Lee, Jae-Hyun

Journal of dentistry

2024 Volume 144, Page(s) 104969

Abstract: Objectives: Natural teeth and dental restorations present with various shades and levels of translucency. This study aimed to determine whether these variations in ceramic crowns and scan powder application affect the trueness of intraoral scanners.: ... ...

Abstract	Objectives: Natural teeth and dental restorations present with various shades and levels of translucency. This study aimed to determine whether these variations in ceramic crowns and scan powder application affect the trueness of intraoral scanners. Methods: Eight identical premade resin typodonts, each prepared for a crown on the maxillary right second molar, were used. Eight lithium disilicate crowns, distinguished by two levels of translucency (high and low) and four shades (BL1, A2, A3, and A4), were fabricated to an identical design and cemented onto each typodont, providing eight distinct experimental groups (2 levels of translucency × 4 shades). Reference scans were acquired using a desktop scanner. Test scans were performed ten times for each experimental group using two different intraoral scanners (Medit i700 and CEREC Primescan AC), with and without the application of scan powder (n = 10). Three-dimensional metrology software was used to assess the trueness of the intraoral scan datasets. Statistical analysis involved the Kruskal-Wallis H test, Mann-Whitney U test, and independent t-test (α=0.05). Results: For powder-free intraoral scan datasets, the crown shade did not significantly affect trueness within each translucency group (P = 1.000). For both intraoral scanners, compared with low translucency groups, higher marked deviations were exhibited by high translucency groups (P<.001). Scan powder use largely mitigated these differences (P>.05) and enhanced the trueness of the intraoral scan (P<.01). Conclusions: Shade did not significantly influence the trueness of intraoral scans. High-translucency crowns were scanned with less accuracy than were low-translucency crowns. Clinical significance: Unlike tooth shade, translucency significantly affected the accuracy of intraoral scans. Therefore, considering the use of scan powder when scanning objects with high translucency may be beneficial.
MeSH term(s)	Crowns ; Humans ; Dental Prosthesis Design ; Dental Porcelain/chemistry ; Powders ; Computer-Aided Design ; Color ; Prosthesis Coloring ; Imaging, Three-Dimensional/methods ; Ceramics ; Molar/diagnostic imaging ; Molar/anatomy & histology ; Image Processing, Computer-Assisted/methods
Chemical Substances	Dental Porcelain (12001-21-7) ; Powders ; lithia disilicate
Language	English
Publishing date	2024-03-26
Publishing country	England
Document type	Journal Article
ZDB-ID	186068-9
ISSN	1879-176X ; 0300-5712
ISSN (online)	1879-176X
ISSN	0300-5712
DOI	10.1016/j.jdent.2024.104969
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Article: In Vitro Comparison between Metal Sleeve-Free and Metal Sleeve-Incorporated 3D-Printed Computer-Assisted Implant Surgical Guides.

Oh, Kyung Chul / Shim, June-Sung / Park, Ji-Man

Materials (Basel, Switzerland)

2021 Volume 14, Issue 3

Abstract: The present study aims to compare the accuracy of metal sleeve-free 3D-printed computer-assisted implant surgical guides (MSF group) ( ...

Abstract	The present study aims to compare the accuracy of metal sleeve-free 3D-printed computer-assisted implant surgical guides (MSF group) (
Language	English
Publishing date	2021-01-29
Publishing country	Switzerland
Document type	Journal Article
ZDB-ID	2487261-1
ISSN	1996-1944
ISSN	1996-1944
DOI	10.3390/ma14030615
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Article ; Online: Development of a Real-Time 6-DOF Motion-Tracking System for Robotic Computer-Assisted Implant Surgery.

Sin, Minki / Cho, Jang Ho / Lee, Hyukjin / Kim, Kiyoung / Woo, Hyun Soo / Park, Ji-Man

Sensors (Basel, Switzerland)

2023 Volume 23, Issue 5

Abstract: In this paper, we investigate a motion-tracking system for robotic computer-assisted implant surgery. Failure of the accurate implant positioning may result in significant problems, thus an accurate real-time motion-tracking system is crucial for ... ...

Abstract	In this paper, we investigate a motion-tracking system for robotic computer-assisted implant surgery. Failure of the accurate implant positioning may result in significant problems, thus an accurate real-time motion-tracking system is crucial for avoiding these issues in computer-assisted implant surgery. Essential features of the motion-tracking system are analyzed and classified into four categories: workspace, sampling rate, accuracy, and back-drivability. Based on this analysis, requirements for each category have been derived to ensure that the motion-tracking system meets the desired performance criteria. A novel 6-DOF motion-tracking system is proposed which demonstrates high accuracy and back-drivability, making it suitable for use in computer-assisted implant surgery. The results of the experiments confirm the effectiveness of the proposed system in achieving the essential features required for a motion-tracking system in robotic computer-assisted implant surgery.
MeSH term(s)	Robotic Surgical Procedures/methods ; Robotics/methods ; Surgery, Computer-Assisted/methods ; Motion ; Computers
Language	English
Publishing date	2023-02-22
Publishing country	Switzerland
Document type	Journal Article
ZDB-ID	2052857-7
ISSN	1424-8220 ; 1424-8220
ISSN (online)	1424-8220
ISSN	1424-8220
DOI	10.3390/s23052450
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