1.Effect of 50-Hz Filters on Pattern Electroretinogram
Dong Hee HA ; Nam Ju MOON ; Ungsoo Samuel KIM
Korean Journal of Ophthalmology 2025;39(3):241-245
Purpose:
Pattern electroretinogram (PERG) is used to evaluate the function of retinal ganglion cells. However, the amplitude of PERG is quite small, making the examination challenging to perform. Waveform noise may be minimized by applying various filters. We aimed to investigate the effect of 50-Hz filters on PERG test results.
Methods:
This is the retrospective observational study. PERG tests were performed using the RETI-scan system according to the International Society for Clinical Electrophysiology of Vision guidelines. Three types of 50-Hz filters (soft, middle, and hard) were applied. The differences in parameters (N35 peak time, P50 peak time, N95 peak time, P50 amplitude, N95 amplitude, and N95 to P50 ratio) were analyzed. Based on the provided normal range, the changes from normal to abnormal range or vice versa were investigated.
Results:
A total of 24 waveforms were analyzed. After filtering, the P50 and N95 amplitudes showed a significant reduction of 8% to 15% (P50 amplitude: 5.1 ± 2.7 μV without filter, 4.6 ± 2.3 μV with 50-Hz soft filter, 4.3 ± 2.1 μV with 50-Hz middle filter, 4.3 ± 2.1 μV with 50-Hz hard filter; N95 amplitude: 7.2 ± 4.2 μV without filter, 6.6 ± 3.8 μV with 50-Hz soft filter, 6.3 ± 3.6 μV with 50-Hz middle filter, 6.1 ± 3.6 μV with 50-Hz hard filter). This pattern was more prominent in normal subjects. All latencies except the N35 peak time exhibited no differences between the tests. The N95 to P50 ratio decreased after 50-Hz middle and hard filtering. Considering the normative data, switching between normal and abnormal results was rare.
Conclusions
Although peak time was not significantly affected, amplitude was significantly reduced after using 50-Hz filters. Thus, 50-Hz filters can smoothen the waveform. Nevertheless, caution must be exercised while taking readings.
2.Deformation analysis of 3D-printed three-unit fixed partial dentures according to various cleaning strategies after DLP 3D printing:a geometric library matching approach
Yuwon JEONG ; Sang-Yeop CHUNG ; Ju Ri YE ; Ok Hyung NAM ; Hyeonjong LEE
The Journal of Advanced Prosthodontics 2025;17(1):11-21
PURPOSE:
Three-dimensional (3D) printing must go through a post-processing procedure. This study aimed to evaluate the effects of different cleaning methods on 3D printed three-unit fixed partial dentures using 3D analysis.
MATERIALS AND METHODS:
A three-unit fixed partial denture was designed and printed using two different printers. The evaluation was taken regarding cleaning method with ethanol (ETH) or isopropanol (IPA), and combining ultrasonic (US) technique for the following groups: group 1, ETH; group 2, ETH+US; group 3, IPA; group 4, IPA+US; and group 5, US. The 3D evaluation was conducted by calculating the mean distance between two specific points and analyzing various angular deviations, utilizing the geometry-embedded library. In addition, visual analysis was performed by creating sectional planes in different points of view. Normality test and independent t-test were performed to compare results between the two printers used in this study. In addition, one-way ANOVA was performed to compare cleaning method groups.
RESULTS:
Mean distance results showed statistical differences between printers for groups IPA, US, and IPA+US, whereas no significant differences were found among cleaning methods. Angular measurements were taken at the bucco-lingual, proximal, and occlusal planes to assess deviations in the internal surfaces. Overall results showed a tendency of shrinkage of the printed three-unit fixed partial denture.
CONCLUSION
Ultrasonic treatment may impact the washing efficiency when used with other cleaning solutions regarding angular and longitudinal deformation. Adequate selection of post-processing methods is crucial to decrease morphological deformities in 3D printed materials.
3.The Challenge of Trans-Ulnar Basal Coronoid Fracture-Dislocations: A Surgical Strategy Based on the Pattern of Coronoid Fracture
Hyoung-Seok JUNG ; Hyun-Cheul NAM ; Min Su CHU ; Jae-Sung LEE
Clinics in Orthopedic Surgery 2025;17(2):300-307
Background:
The rarity and complexity of trans-ulnar basal coronoid fracture-dislocations pose significant challenges in treatment. This study aimed to categorize these fractures based on coronoid fracture patterns and propose tailored surgical approaches for each type. Additionally, we evaluated the functional and radiological outcomes among the patients managed using our treatment algorithm.
Methods:
A total of 19 patients who underwent open reduction and internal fixation for trans-ulnar basal coronoid fracture-dislocations between March 2018 and October 2022 were enrolled in this study. These patients were classified based on the coronoid fracture patterns associated with olecranon fractures: type 1 involved anteromedial facet (AMF) fractures, type 2 encompassed coronoid base and body fractures, and type 3 involved a combination of types 1 and 2. We made a midline longitudinal dorsal incision to facilitate the provisional fixation of the olecranon fragment to the distal metaphysis using a locking plate. Subsequently, we employed the over-the-top (type 1) and Taylor–Scham (type 3) approaches for direct coronoid process fixation with buttress plating.Type 2 fractures were approached via medial fascial exposure from the posterior ulnar cortex or through the olecranon fractures, and subsequently fixed with miniplates and screws. Bony union and joint articulation were assessed via plain radiographs, and functional outcomes were evaluated using range of motion and the Mayo Elbow Performance Score.
Results:
Among the 19 patients, 3 had type 1 fractures, 14 had type 2 fractures, and 2 had type 3 fractures. All fractures exhibited solid osseous union without subluxation or dislocation. The average flexion and extension arc was 119.47° ± 20.88°, with a mean flexion of 127.37° ± 13.37° and an average flexion contracture of 7.89° ± 10.04°. The average Mayo Elbow Performance Score was 82.63 ± 12.51 points. Qualitatively, patient outcomes were excellent in 5 patients, good in 9, and fair in 5.
Conclusions
Most of our patients presented with easily approachable coronoid base and body fractures. However, in AMF fractures of the coronoid process, a direct medial approach is required for buttress plating. We believe our study helps provide useful guidelines for making appropriate decisions in trans-ulnar basal coronoid fracture-dislocations .
4.Effects of Pancreatitis and Type 2 Diabetes Mellitus on the Development of Pancreatic Cancer: A Nationwide Nested Case-Control Study
Young-eun KIM ; Min Heui YU ; Chung Mo NAM ; Eun Seok KANG
Diabetes & Metabolism Journal 2025;49(2):252-263
Background:
Despite diabetes mellitus (DM) and pancreatitis being known risk factors for pancreatic cancer, patients with these conditions are not included in pancreatic cancer screening due to the low incidence of pancreatic cancer in these populations. This study aimed to determine the high-risk subgroup of patients with diabetes and pancreatitis that would benefit from pancreatic cancer screening.
Methods:
A nested case-control study was conducted using data from the National Health Information Database of the Korean National Health Insurance Service. Patients were categorized into the following groups: type 2 diabetes mellitus only (T2DM-only), pancreatitis-only (PAN-only), T2DM followed by pancreatitis (T2DM-PAN), post-pancreatitis diabetes mellitus (PPDM), and no diabetes and no pancreatitis (NDNP). Conditional logistic regression was used to determine significant associations of each group with pancreatic cancer development risk.
Results:
The risk of pancreatic cancer was significantly higher in the T2DM-PAN (adjusted odds ratio [AOR], 4.96; 95% confidence interval [CI], 4.48 to 5.49) and PPDM (AOR, 4.71; 95% CI, 4.12 to 5.37) groups than in the NDNP group. Compared to patients in the NDNP group, those with PPDM using insulin had a 17-fold increased risk (AOR, 16.72; 95% CI, 9.50 to 29.43), and individuals with PPDM who had diabetes for less than 3 years had a more than 8-fold increased risk of pancreatic cancer (AOR, 8.83; 95% CI, 5.99 to 13.01).
Conclusion
In patients with post-pancreatitis diabetes, insulin use or shorter duration of diabetes was associated with a higher risk of pancreatic cancer, suggesting that patients in these subgroups may require close monitoring for pancreatic cancer development.
7.Comparative analysis of postoperative outcomes of single-incision cholecystectomy: Propensity score matching of robotic surgery using the da Vinci SP system and da Vinci Xi system vs. laparoscopic surgery
Jeong-Ik PARK ; Yong-Kyu CHUNG ; Young Min LEE ; Chang Woo NAM ; Yang Won NAH
Annals of Hepato-Biliary-Pancreatic Surgery 2025;29(2):140-149
Background:
s/Aims: We compared the postoperative outcomes of single-incision laparoscopic cholecystectomy (SILC) with those of single-incision robotic cholecystectomy (SIRC) using the da Vinci Xi and SP systems.
Methods:
We retrospectively analyzed data from 206 patients who underwent these procedures by a single surgeon between August 2020 and April 2022. Propensity score matching was used to adjust for confounders and evaluate outcomes.
Results:
SILC exhibited shorter operation times compared to SIRC with Xi and SP (44.9 ± 14.5 min vs. 55.3 ± 12.2 min vs. 55.2 ± 16.2 min, p < 0.001). SIRC with Xi had shorter docking times (6.2 ± 2.8 min vs. 10.3 ± 2.3 min, p < 0.001), while SIRC with SP demonstrated reduced console times (11.2 ± 2.4 min vs. 18.6 ± 8.0 min, p < 0.001). Pain scores and complications did not significantly differ between the groups.
Conclusions
Both SILC and SIRC showed comparable outcomes, with the SP system providing advantages such as reduced console time and fully articulated arms, likely reducing surgeon stress.
8.Effect of 50-Hz Filters on Pattern Electroretinogram
Dong Hee HA ; Nam Ju MOON ; Ungsoo Samuel KIM
Korean Journal of Ophthalmology 2025;39(3):241-245
Purpose:
Pattern electroretinogram (PERG) is used to evaluate the function of retinal ganglion cells. However, the amplitude of PERG is quite small, making the examination challenging to perform. Waveform noise may be minimized by applying various filters. We aimed to investigate the effect of 50-Hz filters on PERG test results.
Methods:
This is the retrospective observational study. PERG tests were performed using the RETI-scan system according to the International Society for Clinical Electrophysiology of Vision guidelines. Three types of 50-Hz filters (soft, middle, and hard) were applied. The differences in parameters (N35 peak time, P50 peak time, N95 peak time, P50 amplitude, N95 amplitude, and N95 to P50 ratio) were analyzed. Based on the provided normal range, the changes from normal to abnormal range or vice versa were investigated.
Results:
A total of 24 waveforms were analyzed. After filtering, the P50 and N95 amplitudes showed a significant reduction of 8% to 15% (P50 amplitude: 5.1 ± 2.7 μV without filter, 4.6 ± 2.3 μV with 50-Hz soft filter, 4.3 ± 2.1 μV with 50-Hz middle filter, 4.3 ± 2.1 μV with 50-Hz hard filter; N95 amplitude: 7.2 ± 4.2 μV without filter, 6.6 ± 3.8 μV with 50-Hz soft filter, 6.3 ± 3.6 μV with 50-Hz middle filter, 6.1 ± 3.6 μV with 50-Hz hard filter). This pattern was more prominent in normal subjects. All latencies except the N35 peak time exhibited no differences between the tests. The N95 to P50 ratio decreased after 50-Hz middle and hard filtering. Considering the normative data, switching between normal and abnormal results was rare.
Conclusions
Although peak time was not significantly affected, amplitude was significantly reduced after using 50-Hz filters. Thus, 50-Hz filters can smoothen the waveform. Nevertheless, caution must be exercised while taking readings.
9.Deformation analysis of 3D-printed three-unit fixed partial dentures according to various cleaning strategies after DLP 3D printing:a geometric library matching approach
Yuwon JEONG ; Sang-Yeop CHUNG ; Ju Ri YE ; Ok Hyung NAM ; Hyeonjong LEE
The Journal of Advanced Prosthodontics 2025;17(1):11-21
PURPOSE:
Three-dimensional (3D) printing must go through a post-processing procedure. This study aimed to evaluate the effects of different cleaning methods on 3D printed three-unit fixed partial dentures using 3D analysis.
MATERIALS AND METHODS:
A three-unit fixed partial denture was designed and printed using two different printers. The evaluation was taken regarding cleaning method with ethanol (ETH) or isopropanol (IPA), and combining ultrasonic (US) technique for the following groups: group 1, ETH; group 2, ETH+US; group 3, IPA; group 4, IPA+US; and group 5, US. The 3D evaluation was conducted by calculating the mean distance between two specific points and analyzing various angular deviations, utilizing the geometry-embedded library. In addition, visual analysis was performed by creating sectional planes in different points of view. Normality test and independent t-test were performed to compare results between the two printers used in this study. In addition, one-way ANOVA was performed to compare cleaning method groups.
RESULTS:
Mean distance results showed statistical differences between printers for groups IPA, US, and IPA+US, whereas no significant differences were found among cleaning methods. Angular measurements were taken at the bucco-lingual, proximal, and occlusal planes to assess deviations in the internal surfaces. Overall results showed a tendency of shrinkage of the printed three-unit fixed partial denture.
CONCLUSION
Ultrasonic treatment may impact the washing efficiency when used with other cleaning solutions regarding angular and longitudinal deformation. Adequate selection of post-processing methods is crucial to decrease morphological deformities in 3D printed materials.
10.Effect of 50-Hz Filters on Pattern Electroretinogram
Dong Hee HA ; Nam Ju MOON ; Ungsoo Samuel KIM
Korean Journal of Ophthalmology 2025;39(3):241-245
Purpose:
Pattern electroretinogram (PERG) is used to evaluate the function of retinal ganglion cells. However, the amplitude of PERG is quite small, making the examination challenging to perform. Waveform noise may be minimized by applying various filters. We aimed to investigate the effect of 50-Hz filters on PERG test results.
Methods:
This is the retrospective observational study. PERG tests were performed using the RETI-scan system according to the International Society for Clinical Electrophysiology of Vision guidelines. Three types of 50-Hz filters (soft, middle, and hard) were applied. The differences in parameters (N35 peak time, P50 peak time, N95 peak time, P50 amplitude, N95 amplitude, and N95 to P50 ratio) were analyzed. Based on the provided normal range, the changes from normal to abnormal range or vice versa were investigated.
Results:
A total of 24 waveforms were analyzed. After filtering, the P50 and N95 amplitudes showed a significant reduction of 8% to 15% (P50 amplitude: 5.1 ± 2.7 μV without filter, 4.6 ± 2.3 μV with 50-Hz soft filter, 4.3 ± 2.1 μV with 50-Hz middle filter, 4.3 ± 2.1 μV with 50-Hz hard filter; N95 amplitude: 7.2 ± 4.2 μV without filter, 6.6 ± 3.8 μV with 50-Hz soft filter, 6.3 ± 3.6 μV with 50-Hz middle filter, 6.1 ± 3.6 μV with 50-Hz hard filter). This pattern was more prominent in normal subjects. All latencies except the N35 peak time exhibited no differences between the tests. The N95 to P50 ratio decreased after 50-Hz middle and hard filtering. Considering the normative data, switching between normal and abnormal results was rare.
Conclusions
Although peak time was not significantly affected, amplitude was significantly reduced after using 50-Hz filters. Thus, 50-Hz filters can smoothen the waveform. Nevertheless, caution must be exercised while taking readings.

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