The machining accuracy of zirconia prostheses fabricated by the subtractive (SM) and additive manufacturing (AM) was evaluated using the Merlon fracture test model in ISO 18675 (2022). The SM specimens were fabricated by a DWX-51D (Roland, Sydney, NSW, Australia) using two zirconia blocks (Katana Zirconia HT; KH, Katana Zirconia STML; KS). The AM specimens were prepared by a DLP type 3D printer INNI-Ⅱ (AON, Gunpo, Korea) using zirconia liquid slurry (INNI-CERA; PZ). The specimen STL image was acquired using a model scanner (E3, 3 Shape A/S, Copenhagen, Denmark). The machining accuracy of the specimens was analyzed by the RMS method superimposing the reference STL image and the specimen STL image in image analysis software (Geomagic Control X, 3D Systems, Rock Hill, SC, USA). From the results of the machining accuracy analysis, the KH and KS groups showed statistically significantly better machining accuracy (lower RMS) than the PZ group (P<0.05). The KH and KS groups showed higher machining accuracy as the thickness decreased, and the 0.2 mm and 0.3 mm experimental groups showed statistically significantly better machining accuracy than the 0.4 mm experimental group (P<0.05). On the other hand, the PZ group showed better machining accuracy as the thickness increased, with the 0.4 mm group showing statistically significantly better machining accuracy than the 0.2 mm and 0.3 mm groups (P<0.05). Within the limitation of this study, the thickness of the final zirconia prosthesis fabricated by additive manufacturing should be at least 0.4 mm for clinical use in dentistry.

Background/Aims: Helicobacter pylori eradication can reduce the incidence of metachronous gastric neoplasm (MGN) after endoscopic submucosal dissection (ESD) for early gastric cancer (EGC). This study evaluated the risk of developing MGN after ESD for EGC based on age at H.pylori eradication. Methods: Data of patients who underwent curative ESD for EGC with H. pylori infection between 2005 and 2018 were retrospectively analyzed. The patients were allocated to four groups according to age at H. pylori eradication: group 1 (<50 years), group 2 (50–59 years), group 3 (60–69years), and group 4 (≥70 years). Results: All patients were followed up for at least 5 years after ESD. The 5-year cumulative incidence of MGN was 2.1%, 7.0%, 8.7%, and 16.7% in groups 1, 2, 3, and 4, respectively (p<0.001), and groups 3 and 4 showed a significant increase in the risk of MGN (hazard ratio [HR], 4.66; 95% confidence interval [CI], 1.09 to 19.92 and HR, 10.75; 95% CI, 2.45 to 47.12).After adjustments for moderate to severe intestinal metaplasia based on the updated Sydney system, groups 3 and 4 remained significantly associated with MGN (HR, 4.40; 95% CI, 1.03 to 18.84 and HR, 10.14; 95% CI, 2.31 to 44.57). Conclusions The incidence of MGN after ESD for EGC increased with age at H. pylori eradication. Age at H. pylori eradication ≥60 years was an independent risk factor for MGN, even after adjusting for the presence of advanced intestinal metaplasia.

Background/Aims: Helicobacter pylori eradication can reduce the incidence of metachronous gastric neoplasm (MGN) after endoscopic submucosal dissection (ESD) for early gastric cancer (EGC). This study evaluated the risk of developing MGN after ESD for EGC based on age at H.pylori eradication. Methods: Data of patients who underwent curative ESD for EGC with H. pylori infection between 2005 and 2018 were retrospectively analyzed. The patients were allocated to four groups according to age at H. pylori eradication: group 1 (<50 years), group 2 (50–59 years), group 3 (60–69years), and group 4 (≥70 years). Results: All patients were followed up for at least 5 years after ESD. The 5-year cumulative incidence of MGN was 2.1%, 7.0%, 8.7%, and 16.7% in groups 1, 2, 3, and 4, respectively (p<0.001), and groups 3 and 4 showed a significant increase in the risk of MGN (hazard ratio [HR], 4.66; 95% confidence interval [CI], 1.09 to 19.92 and HR, 10.75; 95% CI, 2.45 to 47.12).After adjustments for moderate to severe intestinal metaplasia based on the updated Sydney system, groups 3 and 4 remained significantly associated with MGN (HR, 4.40; 95% CI, 1.03 to 18.84 and HR, 10.14; 95% CI, 2.31 to 44.57). Conclusions The incidence of MGN after ESD for EGC increased with age at H. pylori eradication. Age at H. pylori eradication ≥60 years was an independent risk factor for MGN, even after adjusting for the presence of advanced intestinal metaplasia.

Background/Aims: Helicobacter pylori eradication can reduce the incidence of metachronous gastric neoplasm (MGN) after endoscopic submucosal dissection (ESD) for early gastric cancer (EGC). This study evaluated the risk of developing MGN after ESD for EGC based on age at H.pylori eradication. Methods: Data of patients who underwent curative ESD for EGC with H. pylori infection between 2005 and 2018 were retrospectively analyzed. The patients were allocated to four groups according to age at H. pylori eradication: group 1 (<50 years), group 2 (50–59 years), group 3 (60–69years), and group 4 (≥70 years). Results: All patients were followed up for at least 5 years after ESD. The 5-year cumulative incidence of MGN was 2.1%, 7.0%, 8.7%, and 16.7% in groups 1, 2, 3, and 4, respectively (p<0.001), and groups 3 and 4 showed a significant increase in the risk of MGN (hazard ratio [HR], 4.66; 95% confidence interval [CI], 1.09 to 19.92 and HR, 10.75; 95% CI, 2.45 to 47.12).After adjustments for moderate to severe intestinal metaplasia based on the updated Sydney system, groups 3 and 4 remained significantly associated with MGN (HR, 4.40; 95% CI, 1.03 to 18.84 and HR, 10.14; 95% CI, 2.31 to 44.57). Conclusions The incidence of MGN after ESD for EGC increased with age at H. pylori eradication. Age at H. pylori eradication ≥60 years was an independent risk factor for MGN, even after adjusting for the presence of advanced intestinal metaplasia.

Background/Aims: Helicobacter pylori eradication can reduce the incidence of metachronous gastric neoplasm (MGN) after endoscopic submucosal dissection (ESD) for early gastric cancer (EGC). This study evaluated the risk of developing MGN after ESD for EGC based on age at H.pylori eradication. Methods: Data of patients who underwent curative ESD for EGC with H. pylori infection between 2005 and 2018 were retrospectively analyzed. The patients were allocated to four groups according to age at H. pylori eradication: group 1 (<50 years), group 2 (50–59 years), group 3 (60–69years), and group 4 (≥70 years). Results: All patients were followed up for at least 5 years after ESD. The 5-year cumulative incidence of MGN was 2.1%, 7.0%, 8.7%, and 16.7% in groups 1, 2, 3, and 4, respectively (p<0.001), and groups 3 and 4 showed a significant increase in the risk of MGN (hazard ratio [HR], 4.66; 95% confidence interval [CI], 1.09 to 19.92 and HR, 10.75; 95% CI, 2.45 to 47.12).After adjustments for moderate to severe intestinal metaplasia based on the updated Sydney system, groups 3 and 4 remained significantly associated with MGN (HR, 4.40; 95% CI, 1.03 to 18.84 and HR, 10.14; 95% CI, 2.31 to 44.57). Conclusions The incidence of MGN after ESD for EGC increased with age at H. pylori eradication. Age at H. pylori eradication ≥60 years was an independent risk factor for MGN, even after adjusting for the presence of advanced intestinal metaplasia.

BACKGROUND: In guided bone regeneration (GBR), there are various problems that occur in the bone defect after the wound healing period. This study aimed to investigate the enhancement of the osteogenic ability of the dual scaffold complex and identify the appropriate concentration of growth factors (GF) for new bone formation based on the novel GBR concept that is applying rapid bone forming GFs to the membrane outside of the bone defect. METHODS: Four bone defects with a diameter of 8 mm were formed in the calvaria of New Zealand white rabbits each to perform GBR. Collagen membrane and biphasic calcium phosphate (BCP) were applied to the bone defects with the four different concetration of BMP-2 or FGF-2. After 2, 4, and 8 weeks of healing, histological, histomorphometric, and immunohistochemical analyses were conducted. RESULTS: In the histological analysis, continuous forms of new bones were observed in the upper part of bone defect in the experimental groups, whereas no continuous forms were observed in the control group. In the histomorphometry, The group to which BMP-2 0.5 mg/ml and FGF-2 1.0 mg/ml was applied showed statistically significantly higher new bone formation. Also, the new bone formation according to the healing period was statistically significantly higher at 8 weeks than at 2, 4 weeks. CONCLUSION The novel GBR method in which BMP-2, newly proposed in this study, is applied to the membrane is effective for bone regeneration. In addition, the dual scaffold complex is quantitatively and qualitatively advantageous for bone regeneration and bone maintenance over time.

The aim of this study was to evaluate the differences in setting times based on the methods for dental root canal sealers and calcium silicate cement used in root-end filling. Five kinds of dental root canal sealers and four kinds of calcium silicate cement for root-end filling were selected for the experiments. All materials were mixed according to the manufacturers’ instructions and stored at 37 ℃ with a relative humidity of 95%. Setting time was measured using a 1/4 pound Gillmore needle and a 1 pound Gillmore needle to determine the time until indentation was no longer visible or the time until 2 mm penetration was no longer possible. The determination of indentation was based on the absence of visible impressions on the material surface when Gillmore needle was placed vertically. When comparing indentation time and penetration time using same type of Gillmore needle, only ProRoot MTA using 1 pound Gillmore needle showed significant difference between measuring methods (P<0.05) while there are no differences in measuring methods in other materials (P>0.05). By this study, we could expect to measure a setting time relatively similar to real clinical conditions through indentation method.

Ni-Ti-O nanotubes have the potential for visible light-mediated light absorption and photocatalysis due to their low energy band gap. However, their photocatalytic-based antibacterial activity under visible light irradiation is still unclear. This study aims to analyze the photocatalytic-based optical properties of Ni-Ti-O nanotubes and evaluate their antibacterial activity. From the FE-SEM observations of the Ni-Ti-O nanotubes, clean and homogeneous nanotubes with a length of 600 ± 80 ㎚ and an outer diameter of 52 ± 5 ㎚ were observed. The diffuse reflection analysis of the Ni-Ti-O nanotubes showed a photocatalytic bandgap, which is equivalent to the wavenumber of 450 nm, indicating that they exhibit photocatalytic effects in the visible light range. The CFU antibacterial test and SOD enzyme activity test using Streptococcus sanguinis showed that the Ni-Ti-O nanotube experimental group under 470 nm visible light irradiation exhibited statistically significant antibacterial activity compared to other experimental groups (P< 0.05). Therefore, the combination of Ni-Ti-O nanotubes and visible light-based photofunctionalization is expected to improve the antibacterial ability of NiTi implant materials in the dental field.

This study aimed to optimize the cleaning process of the anodized specimens for fabricating clean NiTi-O nanotubes exhibiting visible light-mediated antibacterial activity at the surface of NiTi alloy. The cleaning process of the anodized specimens tested in this study was composed of two steps. The First step included two washing solvents (distilled water and heptane) with different washing times (1, 3, and 5 min) and temperatures (25 and 80 ℃), and the second step was treated by ultrasonicator (1, 3, and 5 min). From the results of FE-SEM observation, clean and uniform nanotubes (length: 600±80 nm, diameter: 52 ±5 nm) at the surface of NiTi alloy were observed on the condition of 5 min of washing in heptane at 25 ℃ and then 3 min of ultrasonication. Thin film XRD analysis resulted that the brookite TiO 2 crystal structure being detected in the anodized specimen. Furthermore, the live-dead assay resulted that there was no significant difference among the cell viability numbers of hMSCs cultured on a cell culture dish (control), NiTi alloy, and NiTi-O nanotubes (P>0.05). Therefore, the optimized cleaning process of the anodized NiTi alloy is expected to be more feasible for the NiTi alloy-based implant surface treatment technology.

The purpose of this study was to evaluate the effect of vacuum heat treatment on the visible light remote-controlled drug release and consequent antimicrobial activity of gold nanoparticles coated on the surface of titania nanotubes. After the plasma coating of gold nanoparticles on a titania nanotube with a diameter of 100 nm, a homogeneously spherical gold shaped nanoparticle deposited on titania nanotube specimen was prepared through a vacuum heat treatment process. From the measurement of the diffuse reflective ultraviolet-visible-near-infrared spectrophotometer, the vacuum heated gold nanoparticles-titania nanotubes showed strong light absorption at the range of 400 to 650 nm. From the observation of field emission scanning electron microscopy, the size of the nanoparticles increased from 5.59±1.05 nm to 56.93±10.91 nm, and the aspect ratio also increased from 1.01±0.31 to 1.55±0.47, as the gold coating time increased from 1 minute to 9 minutes, respectively. From the results of antimicrobial drug elution test and the antibacterial test using Streptococcus mutans, before and after the visible light (wavelength 550 nm) irradiation of the antimicrobial drug (a polylactic acid containing 0.1% tetracycline) coated specimen, the drug elution value of the experimental group subjected to visible light irradiation was significantly higher than that of the control group without light irradiation (P<0.05). Also, significant antibacterial effect was evident in the experimental group subjected to visible light irradiation (P<0.05). Therefore, the study concluded that there is a possibility as an antimicrobial implant material with a visible light remote control drug elution function with the surface treatment technology of gold nanoparticles-titania nanotubes spheroidized using vacuum heat treatment.