The Direction of Neurosurgery to Overcome the Living with COVID-19 Era : The Possibility of Telemedicine in Neurosurgery

Objective@#: Due to the implementation of vaccinations and the development of therapeutic agents, the coronavirus disease 2019 (COVID-19) pandemic that started at the end of 2019 has entered a new phase. As a result, neurosurgeons should reconsider the way they treat their patients. As the COVID-19 situation prolongs, the change in neurosurgical emergency patients according to the number of confirmed cases is no longer clear. Outpatient treatment by telephone was permitted according to government policy. In addition, visits to caregivers in the intensive care unit were limited. @*Methods@#: The electronic medical records of patients who had been treated over the phone for a month (during April 2020, while the hospital was closing) were reviewed. Meanwhile, according to the limited visits to the intensive care unit, a video meeting was held with the caregivers. After the video meeting, satisfaction was evaluated using a questionnaire. @*Results@#: During April 2020, 1021 patients received non-face-to-face care over the telephone. Among the patients, no critical medical problem occurred due to non-face-to-face care. From July 2021 to December 2021, 321 patients were admitted to the neurosurgical intensive care unit and 107 patients (33.3%) including their caregivers agreed to video visits. Twice a week, advance notice was given that access would be made through a mobile device and the nurse explained to caregivers how to use the mobile device. The time for the video meeting was approximately 20 minutes per patient. Based on the questionnaire, 81 respondents (75.7%) answered that they agreed, and 26 respondents (24.3%) answered that they strongly agreed that was easy to communicate through video meetings. Fifty-two (48.6%) agreed and 55 (51.4%) strongly agreed that they were easy to understand the doctor’s explanation. For overall satisfaction with this video meeting, three respondents (2.8%) gave 4/5 points and 95 respondents (88.8%) gave 5/5 points, and nine (8.4%) gave 3/5 points. Their reason was that there was not enough time. @*Conclusion@#: In situations where patient visits are limited, video meetings through a mobile device can provide sufficient satisfaction to caregivers. Telemedicine will likely become common in the near future. Health care professionals should prepare and respond to these needs and changes. Therefore, establishing a system with institutional support is necessary.

Balancing Bleeding Risk and Thromboembolic Complications in Elderly Chronic Subdural Hematoma Patients Undergoing Burr Hole Trephination : A Multicenter Retrospective Cohort Study and Literature Review

Objective@#: Chronic subdural hematoma (CSDH) patients using antithrombotic agents (AT) at high risk for cardiovascular disease are increasing. The authors aimed to analyze the factors influencing outcome by targeting patients using AT and to establish a desirable treatment strategy. @*Methods@#: A retrospective analysis was performed on data from 462 patients who underwent burr hole trephination (BHT) surgery for CSDH at five hospitals from March 2010 to June 2021. Outcomes included incidence of postoperative acute bleeding, recurrence rate, and morbidity or mortality rate. Patients were divided into the following four groups based on their history of AT use : no AT. Only antiplatelet agents (AP), only anticoagulants (AC), both of AP and AC. In addition, a concurrent literature review was conducted alongside our cohort study. @*Results@#: Of 462 patients, 119 (119/462, 25.76%) were using AT. AP prescription did not significantly delay surgery (p=0.318), but AC prescription led to a significant increase in the time interval from admission to operation (p=0.048). After BHT, AP or AC intake significantly increased the period required for an in-dwelling drain (p=0.026 and p=0.037). The use of AC was significantly related to acute bleeding (p=0.044), while the use of AP was not (p=0.808). Use of AP or AC had no significant effect on CSDH recurrence (p=0.517 and p=1.000) or reoperation (p=0.924 and p=1.000). Morbidity was not statistically correlated with use of either AP or AC (p=0.795 and p=0.557, respectively), and there was no significant correlation with mortality for use of these medications (p=0.470 and p=1.000). @*Conclusion@#: Elderly CSDH patients may benefit from maintenance of AT therapy during BHT due to reduced thromboembolic risk. However, the use of AC necessitates individualized due to potential postoperative bleeding. Careful post-operative monitoring could mitigate prognosis and recurrence impacts.

Delayed Detection of a 5-Aminolevulinic Acid In Vivo: A Case of Metastatic Breast Cancer

A 44-year-old female patient who had been diagnosed with breast cancer visited our oncology department. She had developed right-side weakness and mild dysarthria, and MRI revealed a 4-cm cysticenhancing lesion in her left frontal lobe. Her surgery was postponed 48 hours after receiving 5-aminolevulinic acid (5-ALA), because a problem with thyroid function that had not been noticed before was discovered. The main lesion was enhanced on navigation and appeared to be a gross tumor; its 5-ALA uptake was very high. Specimens obtained from this location were histologically confirmed to contain tumor cells. The operation was completed, and removal of all enhancing lesions was confirmed by MRI within 24 hours postoperatively. The pathology report confirmed metastatic ductal carcinoma. The clinical efficacy of 5-ALA was confirmed even 48 hours after administration into a metastatic brain tumor from breast cancer.

The Korean Society for Neuro-Oncology (KSNO) Guideline for the Management of Brain Tumor Patients During the Crisis Period: A Consensus Recommendation Using the Delphi Method (Version 2023.1)

Background@#During the coronavirus disease 2019 (COVID-19) pandemic, the need for appropriate treatment guidelines for patients with brain tumors was indispensable due to the lack and limitations of medical resources. Thus, the Korean Society for Neuro-Oncology (KSNO), a multidisciplinary academic society, has undertaken efforts to develop a guideline that is tailored to the domestic situation and that can be used in similar crisis situations in the future. @*Methods@#The KSNO Guideline Working Group was composed of 22 multidisciplinary experts on neuro-oncology in Korea. In order to reach consensus among the experts, the Delphi method was used to build up the final recommendations. @*Results@#All participating experts completed the series of surveys, and the results of final survey were used to draft the current consensus recommendations. Priority levels of surgery and radiotherapy during crises were proposed using appropriate time window-based criteria for management outcome. The highest priority for surgery is assigned to patients who are life-threatening or have a risk of significant impact on a patient’s prognosis unless immediate intervention is given within 24–48 hours. As for the radiotherapy, patients who are at risk of compromising their overall survival or neurological status within 4–6 weeks are assigned to the highest priority. Curative-intent chemotherapy has the highest priority, followed by neoadjuvant/adjuvant and palliative chemotherapy during a crisis period. Telemedicine should be actively considered as a management tool for brain tumor patients during the mass infection crises such as the COVID-19 pandemic. @*Conclusion@#It is crucial that adequate medical care for patients with brain tumors is maintained and provided, even during times of crisis. This guideline will serve as a valuable resource, assisting in the delivery of treatment to brain tumor patients in the event of any future crisis.

The Korean Society for Neuro-Oncology (KSNO) Guideline for the Management of Brain Tumor Patients During the Crisis Period: A Consensus Survey About Specific Clinical Scenarios (Version 2023.1)

Background@#During the coronavirus disease 2019 (COVID-19) pandemic, there was a shortage of medical resources and the need for proper treatment guidelines for brain tumor patients became more pressing. Thus, the Korean Society for Neuro-Oncology (KSNO), a multidisciplinary academic society, has undertaken efforts to develop a guideline that is tailored to the domestic situation and that can be used in similar crisis situations in the future. As part II of the guideline, this consensus survey is to suggest management options in specific clinical scenarios during the crisis period. @*Methods@#The KSNO Guideline Working Group consisted of 22 multidisciplinary experts on neuro-oncology in Korea. In order to confirm a consensus reached by the experts, opinions on 5 specific clinical scenarios about the management of brain tumor patients during the crisis period were devised and asked. To build-up the consensus process, Delphi method was employed. @*Results@#The summary of the final consensus from each scenario are as follows. For patients with newly diagnosed astrocytoma with isocitrate dehydrogenase (IDH)-mutant and oligodendroglioma with IDH-mutant/1p19q codeleted, observation was preferred for patients with low-risk, World Health Organization (WHO) grade 2, and Karnofsky Performance Scale (KPS) ≥60, while adjuvant radiotherapy alone was preferred for patients with high-risk, WHO grade 2, and KPS ≥60. For newly diagnosed patients with glioblastoma, the most preferred adjuvant treatment strategy after surgery was radiotherapy plus temozolomide except for patients aged ≥70 years with KPS of 60 and unmethylated MGMT promoters. In patients with symptomatic brain metastasis, the preferred treatment differed according to the number of brain metastasis and performance status. For patients with newly diagnosed atypical meningioma, adjuvant radiation was deferred in patients with older age, poor performance status, complete resection, or low mitotic count. @*Conclusion@#It is imperative that proper medical care for brain tumor patients be sustained and provided, even during the crisis period. The findings of this consensus survey will be a useful reference in determining appropriate treatment options for brain tumor patients in the specific clinical scenarios covered by the survey during the future crisis.

Lifestyle Modification in the Management of Metabolic Syndrome:Statement From Korean Society of CardioMetabolic Syndrome (KSCMS)

With the recent rapid increase in obesity worldwide, metabolic syndrome (MetS) has gained significant importance. MetS is a cluster of obesity-related cardiovascular risk factors including abdominal obesity, atherogenic dyslipidemia, high blood pressure and impaired glucose tolerance. MetS is highly prevalent and strongly associated with an increased risk of developing diabetes and cardiovascular disease, putting a great burden on human society. Therefore, it is very important to reduce MetS risk, which can improve patients’cardiovascular prognosis. The primary and most effective strategy to control each component of MetS is lifestyle change such as losing body weight, keeping regular exercise, adopting a healthy diet, quitting smoking and alcohol drinking in moderation. Many studies have shown that lifestyle modification has improved all components of MetS, and reduces the incidence of diabetes and cardiovascular disease. Here, the Korean Society of CardioMetabolic Syndrome has summarized specific and practical methods of lifestyle modification in the management of MetS in the healthcare field.

Comparative Analysis of COVID-19 Outbreak and Changes in Neurosurgical Emergency Patients

Objective@#: COVID-19 has spread worldwide since the first case was reported in Wuhan, China, in December 2019. Our institution is a regional trauma and emergency center in the northern Gyeonggi Province. The changing trend of patient care in the emergency room of this hospital likely reflects the overall trend of patients in the area. In the present study, whether changes in the surrounding social environment following the outbreak of COVID-19 changed the incidence of neurosurgical emergency patients and whether differences in practice existed were investigated. @*Methods@#: The overall trend was analyzed from January 2020 which is before the outbreak of COVID-19 to September 2020. To remove bias due to seasonal variation, the previous 2 year's records during the same period were reviewed and compared. Confirmed COVID-19 patients in the northern Gyeonggi Province were identified using data released by the government. And patients who came to the emergency department with head trauma and stroke were identified. @*Results@#: Based on the present study results, the total number of neurosurgery emergency patients decreased over the study period. In the trauma patient group, the number of patients not involved in traffic accidents significantly decreased compared with patients involved in traffic accidents. Among the stroke cases, the rate of ischemic stroke was lower than hemorrhagic stroke, although a statistically significant difference was not observed. Meanwhile, an increase in the risk of mortality associated with trauma or stroke cases was not observed during the COVID-19 outbreak compared with the same time period in the previous year. @*Conclusion@#: Due to the occurrence of COVID-19, non-essential activities have decreased and trauma cases not associated with traffic accidents appeared to decrease. Due to the decrease in overall activity, the number of stroke patients has also decreased. This trend is expected to continue even in the post-COVID-19 era, and accordingly, the results from the present study are relevant especially if the current situation continues.

Unilateral Internuclear Ophthalmoplegia Following Minor Head Injury / 대한신경손상학회지

A lesion in the medial longitudinal fasciculus (MLF) causes internuclear ophthalmoplegia (INO). Many intracranial lesions, such as multiple sclerosis or vascular disorders may be associated with INO; however, INO is a rare complication of minor head injury. The mechanism underlying injury to the MLF may be shear force on the brain stem during head trauma. The shear force can tear or stretch the fibers of the MLF and can also lead to compromise or rupture of the perforating branches of the basilar artery. We present an unusual case of unilateral INO after minor head injury in a patient with a small site of hemorrhage in the midline of the pontomesencephalic junction, confirmed by brain magnetic resonance imaging using susceptibility-weighted imaging.

Neurotrauma Clinical Practice Guidelines Committee of the Korean Neurotraumatology Society: A Review of a Group That Writes and Inherits the Thoughts and Will of the Society / 대한신경손상학회지

The Neurotrauma Clinical Practice Guidelines Committee of the Korean Neurotraumatology Society (KNTS-NCPGC) is developing clinical guidelines for neurotrauma in line with the capabilities of the Korean Neurotraumatology Society, which is leading pioneering development in the field of neurosurgery. From the mid-1990s, the KNTS-NCPGC has been working to develop guidelines and disseminate evidence-based medicine, including the development of Korean guidelines for the management of severe head injuries and active participation in the Clinical Practice Guidelines Committee of the Korean Academy of Medical Sciences. The KNTS-NCPGC strives to write and inherit the will of the society through the development of clinical practice guidelines, which are one of the outcomes representing professionalism and public interest and can be expressed in terms of “trust” and “best.” In this review, the history and achievements of KNTS-NCPGC, the status of the ongoing development of guidelines, and the perspectives of the committee are covered.

A Radiological Assessment of Chronic Subdural Hematomas / 대한신경손상학회지

Chronic subdural hematoma (CSDH), which generally occurs in elderly patients, is a frequently diagnosed condition in neurosurgical departments. Computed tomography (CT) and magnetic resonance imaging (MRI) are the most preferred diagnostic modalities for CSDH assessment. With early diagnosis and adequate management, CSDH may show favorable prognosis in majority of the patients; however, recurrence after surgery can occur in a significant number of patients. The recently increasing number of CSDH studies could reveal the prognostic factors affecting CSDH recurrence. Particularly, radiological characteristics regarding the internal architecture of CSDH are considered closely associated with recurrence in surgically treated CSDH patients. In this literature review, we evaluated the various diagnostic modalities of CSDH and its radiological characteristics on CT and MRI. Furthermore, we summarized the prognostic factors of recurrence for the hematoma type based on the radiological findings.

Enhancement of bioactivity and osseointegration in Ti-6Al-4V orthodontic mini-screws coated with calcium phosphate on the TiO 2 nanotube layer / 대한치과교정학회지

Objective@#This study evaluated the effect of cyclic pre-calcification treatment on the improvement of bioactivity and osseointegration of Ti-6Al-4V miniscrews. @*Methods@#The experimental groups were: an untreated group (UT), an anodized and heat-treated group (AH), and an anodized treatment followed by cyclic pre-calcification treatment group (ASPH). A bioactive material with calcium phosphate was coated on the mini-screws, and its effects on bioactivity and osseointegration were evaluated in in vitro and in vivo tests of following implantation in the rat tibia. @*Results@#As a result of immersing the ASPH group in simulated body fluid for 2 days, protrusions appearing in the initial stage of hydroxyapatite precipitation were observed. On the 3rd day, the protrusions became denser, other protrusions overlapped and grew on it, and the calcium and phosphorus concentrations increased. The removal torque values increased significantly in the following order: UT group (2.08 ± 0.67 N·cm), AH group (4.10 ± 0.72 N·cm), and ASPH group (6.58 ± 0.66 N·cm) with the ASPH group showing the highest value (p < 0.05). In the ASPH group, new bone was observed that was connected to the threads, and it was confirmed that a bony bridge connected to the adjacent bone was formed. @*Conclusions@#In conclusion, it was found that the surface treatment method used in the ASPH group improved the bioactivity and osseointegration of Ti-6Al-4V orthodontic miniscrews.

Antibacterial effect of biodegradable gelatin methacryloyl loaded with ginger rhizome extract / 대한치과재료학회지

Gelatin methacryloyl 3d mesh mimics the natural extracellular matrix which allow loading as promising drug delivery systems.However, insufficient mechanical and degradation properties remain the biggest obstacle for this material application. In this study, a modified hydrogel with natural phytochemical was developed to improve the antibacterial effect by the addition of ginger extract, a natural spicy used in traditional medicine. GelMA hydrogels with ginger extract were fabricated and their chemical and morphological characteristics were analyzed by Fourier transformer infrared spectroscopy and scanning electron microscopy, structural characteristic were evaluated by compressive test and surface wettability analysis. S. mutans, S. aureus and P. gingivalis were used to confirm the antibacterial effect of the modified hydrogels. The FT-IR spectra of the hydrogels modified with ginger presented an increase in intensity of some peaks in comparison with the 10% GelMA hydrogel. The pores of ginger-modified hydrogels decreased it size which affected the hydrogels physical properties, decreasing the compressive modulus and increasing the durability, swelling ratio and, hydrophobicity of the surface. The ginger-modified hydrogels exhibited excellent antibacterial properties against S. mutans and S. aureus at high concentrations of ginger extract, while P. gingivalis presented a higher sensitivity at all tested concentrations. Hence, this study concludes that ginger-modified GelMA hydrogels presented better antibacterial effect, durability over time and, swelling stability.

Effect of heat treatment time on the properties of lithium disilicate glass-ceramics / 대한치과재료학회지

The objective of the present study was to investigate the effects of heat treatment (HT) time on the optical properties, mechanical properties, and microstructure of lithium disilicate (Li 2 Si 2 O 5) glass-ceramic blocks. Samples were prepared by cutting lithium disilicate glass-ceramic blocks – Amber® Mill Prototype (AMP) and IPS e.max CAD (IEC) – into a disc shape (diameter of 12 mm and thickness of 1.2 mm) and evenly polishing the surface. Each sample was heat treated according to the manufacturer’s manual and HT holding time was set to 15, 30, 45, and 60 minutes according to different groups. The samples were tested by color difference analysis using a spectrophotometer. X-ray diffraction analysis, HR FE-SEM observation, Vickers hardness test, fracture toughness test, and biaxial flexural strength test were carried out. The acicular crystals of lithium disilicate became coarser and less transparent with increasing HT time. The results for color difference (ΔE * ) compared to VITA A2 standard shade showed that the difference was significantly higher in the AMP groups than the IEC groups (P<0.05). Translucency parameter (TP) values were significantly higher in the AMP groups than the IEC groups (P<0.05). The AMP30 group showed the highest TP value, while all other experimental groups showed the tendency of decrease in TP value with increase in HT time. Moreover, increase in TP value was associated with decrease in contrast ratio. When fracture toughness was measured by indentation fracture method, both AMP and IEC groups showed similar results with 1.77 MPa·m 1/2 after HT for 15 minutes. However, as HT time increased, the IEC groups showed significantly higher values than the AMP groups (P<0.05). X-ray diffraction analysis results showed that quartz (SiO 2) and cristobalite (SiO 2) peaks were observed together with the lithium disilicate (Li 2Si 2O 5) peak in the AMP groups, whereas a lithium phosphate (Li 3PO 4) peak was observed together with the lithium disilicate (Li 2Si 2O 5) peak in the IEC groups. With respect to biaxial flexural strength in the AMP groups, the AMP15 group (HT for 15 minutes) showed the highest value of (524.09±89.95) MPa, whereas the AMP60 group (HT for 60 minutes) showed the lowest value of (446.56±76.75) MPa, with a significant difference between the two groups (P<0.05). In the IEC groups, IEC30 group showed the highest value of (668.51±158.57) MPa and the IEC45 group showed the lowest value of (517.37±129.52) MPa, with a significant difference between the two groups (P<0.05). Within the limitations of the present study, it is concluded that if increased strength is required when fabricating restorations using lithium disilicate glass-ceramic, then changing the HT time could be considered as long as such change does not significantly alter the color tone.

Measurement of height of the cricothyroid membrane using cervical-spine computed tomography

Objective@#Emergency cricothyroidotomy is an infrequently performed procedure and post-procedural complications may result from attempting to pass a device with a large external diameter through the cricothyroid membrane. This study aimed to determine the maximum height of the cricothyroid membrane according to the patient’ s sex and age based on cervical-spine computed tomography (C-spine CT) in the emergency department (ED) and determine the appropriate endotracheal tube (ETT) size. @*Methods@#A retrospective analysis of patients was conducted from May 2014 to April 2020 in the ED. The data were obtained from medical records. Electronic calipers were used to measure the maximum height of the cricothyroid membrane in C-spine CT by an emergency physician and an emergency medicine resident. @*Results@#Six hundred and sixty-four patients were included in the study. The mean height of the cricothyroid membrane was 10.11±2.24 mm in males (n=351) and 8.90±1.84 mm in females (n=313) (P<0.001). In males, the cricothyroid membrane height showed significant variance between the ≥75-year-old and the 25-34-year-old groups (9.26±2.40 mm vs. 11.80±2.36 mm) (P<0.001). The tube size of the cricothyroidotomy equipment was suitable for more than 72.1% of patients when applied with an ETT (internal diameter ≤6.0 mm). @*Conclusion@#This study showed that the height of the cricothyroid membrane differed according to sex and also age in males. It may thus be necessary to consider anatomical differences according to sex and age when selecting the appropriate tube size to reduce complications during emergency cricothyroidotomy.

Clinical Characteristics and Current Managements for Patients with Chronic Subdural Hematoma : A Retrospective Multicenter Pilot Study in the Republic of Korea

Objective@#: Chronic subdural hematoma (CSDH) is a common disease in neurosurgical departments, but optimal perioperative management guidelines have not yet been established. We aimed to assess the current clinical management and outcomes for CSDH patients and identify prognostic factors for CSDH recurrence. @*Methods@#: We enrolled a total of 293 consecutive patients with CSDH who underwent burr hole craniostomy at seven institutions in 2018. Clinical and surgery-related characteristics and surgical outcomes were analyzed. The cohort included 208 men and 85 women. @*Results@#: The median patient age was 75 years. Antithrombotic agents were prescribed to 105 patients. History of head trauma was identified in 59% of patients. Two hundred twenty-seven of 293 patients (77.5%) had unilateral hematoma and 46.1% had a homogenous hematoma type. About 70% of patients underwent surgery under general anesthesia, and 74.7% underwent a single burr hole craniostomy surgery. Recurrence requiring surgery was observed in 17 of 293 patients (5.8%), with a median of 32 days to recurrence. The postoperative complication rate was 4.1%. In multivariate analysis, factors associated with CSDH recurrence were separated hematoma type (odds ratio, 3.906; p=0.017) and patient who underwent surgery under general anesthesia had less recurrence (odds ratio, 0.277; p=0.017). @*Conclusion@#: This is the first retrospective multicenter generalized cohort pilot study in the Republic of Korea as a first step towards the development of Korean clinical practice guidelines for CSDH. The type of hematoma and anesthesia was associated with CSDH recurrence. Although the detailed surgical method differs depending on the institution, the surgical treatment of CSDH was effective. Further studies may establish appropriate management guidelines to minimize CSDH recurrence.

The effect of beta-blockers in acute heart failure according to heart rate

Background/Aims@#Beta-blockers (BBs) have been shown to improve clinical outcomes in heart failure (HF) patients. We evaluated the prescribing status of BBs in patients with HF with reduced ejection fraction (HFrEF) at discharge according to the presence or not of bradycardia, and its effect on prognosis. @*Methods@#Study data were obtained from a multicenter cohort of 3,200 patients hospitalized for HF. Patients were classified into four groups according to the presence of bradycardia and use of BBs at discharge. The primary outcome was the incidence of all-cause death during follow-up. @*Results@#Of 1,584 patients with HFrEF, 281 patients died during follow-up (median 523 days, mean 578.5 ± 429.7 days). In patients with bradycardia, the all-cause death rate did not significantly differ according to the use of BBs, but in those patients without bradycardia, the incidence of all-cause death was significantly lower in the BBs group than the no BBs group. Among these four groups, patients with heart rate (HR) ≥ 60 beats/min with no BBs group had the lowest cumulative death-free survival rate. In addition, HR ≥ 60 beats/min with BBs use was independently associated with a 31% reduced risk of all-cause death in patients with HFrEF. @*Conclusions@#BBs had a beneficial effect on clinical prognosis only in those HFrEF patients without bradycardia. Therefore, BBs should be given by clinicians to HF patients without bradycardia to improve their clinical outcomes.

Osteoblast cytocompatibility and antibacterial effect of ginger main compounds / 대한치과재료학회지

Ginger has been used worldwide in traditional medicine. It has been reported that phenolic compounds such as gingerol and shogaol in ginger have beneficial cellular effect and antibacterial effect. The purpose of this study was to investigate the effect of gingerol and shogaol on the cytocompatibility for the osteoblastic cells and antibacterial activity against oral microorganisms. Chemical structures of gingerol and shogaol were determined by Fourier transform infrared (FT-IR). Thermal and pH stability was analyzed by UPLC assay. Streptococcus mutans, and Porphyromonas gingivalis were used to confirm the antibacterial effect of the ginger compounds and MC3T3-E1 cells were used to identify biocompatibility test. Cell viability and bacterial growth was determined by water-soluble tetrazolium salt (WST-8) colorimetric assay. Cellular morphology was identified with optical microscope after crystal violet staining. Cell differentiation and oxidative stress were evaluated by Alkaline phosphatase (ALP) assay and hydrogen peroxide colorimetric assay. The chemical bonding related with hydroxyl groups, carbonyl groups and aromatic ring was identified in all ginger compounds. Gingerol and shogaol presented good stability at acid and neutral pH at room temperature. All compounds showed better antibacterial effect against Porphyromonas gingivalis than Streptococcus mutans. 10-gingerol and all shogaol groups below 10-6 M presented suitable cytocompatibility for osteoblastic cells compared to control group. All groups showed similar Oxidative stress to control group, and ALP activity in all groups below 10-6 M was not statistically significant compared to control. Hence, this study concludes that shogaol groups presented better antibacterial effect and suitable cytocompatibility than gingerol groups.

Effects of microstructural change of zirconia surface on tensile bond strength with resin cement / 대한치과재료학회지

This study was performed to evaluate the effects of microstructural change of zirconia surface on tensile bond strength with resin cement. The zirconia partially sintered block was cut into a size of 18 × 18 × 7 mm, and then the Zirface slurry (DMAX, Daegu, Korea) containing 15% and 30% zirconia was applied and followed by sintering at 1530 ℃ for 2 hours. Resin cement (PermaCem 2.0, DMG, Hamburg, Germany) was applied on zirconia specimen and polymerized to prepare an 18 × 18 × 14 mm block. In addition, for comparison of bond strength, specimens were prepared for the group that was polished and the group that was blasted at 3 atm using 110 µm alumina. Thereafter, all blocks were cut into a cross-sectional area of 1.0 × 1.0 mm to prepare 12 specimens. The specimens were immersed in distilled water at 37 ℃. for 10 days for aging treatment. A holder for tensile testing was attached to each of the specimens, and then a tensile force was applied at a crosshead speed of 0.5 mm/min to measure the fracture load. The fracture surfaces of each test piece was observed with a high-resolution field emission scanning electron microscope. Through the above tests, the following results were obtained. 1. On the blasted surface, zirconia grains were locally removed but on the Zirface treated surface, a porous microstructure was created on the zirconia surface. 2. Arithmetical mean deviation from the mean line ra was the highest in the blasted group and the lowest in the polished group, and as a result of Tukey analysis, there were statistically significant differences between all test groups (P<0.05). 3. The maximum tensile bond strength was 18.8±5.4 MPa in the Zirface 30% group, and as a result of Tukey analysis, there was a statistically significant difference from the other test groups (P<0.05). 4. As a result of observing the fracture surface after the tensile test with a high-resolution field emission scanning electron microscope, in the Zirface 30% group, cohesive fracture and interfacial fracture in the resin was observed, but the other test groups showed the interfacial fracture pattern. In conclusion, within the limits of this study, treating the zirconia surface with Zirface 30% to form a porous microstructure can contribute to the improvement of the bond strength between zirconia and resin cement.

Color comparison of glaze-treated multi-coloured lithium disilicate and zirconia / 대한치과재료학회지

The purpose of this study was to investigate the effect of glazing treatment of multi-colored zirconia disc and lithium disilicate block on the optical properties. From an Ultra Translucent Multi-Layered (UTML) disc containing 50% cubic crystal and a lithium disilicate-based Amber Mill Direct (AMD) block, the 1.2 mm thick specimens of the upper layer (T), the center (M), and the lower layer (B) were prepared. Three types of paste glaze of InSync Glaze Paste, IPS E.max Ceram Glaze Paste, and Amber Ceram G7 Glaze Paste were applied and fired to a uniform thickness on the surface of the specimen. CIE L * , a * , b * values were measured using a spectrophotometer and contrast and translucency were calculated. The bonding interface with the glaze layer was observed using HR FE-SEM. In the glazed groups, L * value increased, but a * value and b * value decreased. The translucency value measured in the untreated group was statically higher in the AMD groups than in UTML groups (P0.05), but significantly decreased compared to the untreated group after glazing treatment in the AMD group (P<0.05). The contrast ratios generally increased after glaze treatment compared to the untreated group. Since the glaze treatment can affect the optical properties of ceramic restorations, the choice of glaze should be considered important for the desired color by the dental technician.

Effect of the cutting flute of the orthodontic miniscrew on insertion and removal torque / 대한치과재료학회지

The purpose of this study was to evaluate the structural characteristics of the thread length of orthodontic mini-screws and the effects of insertion and removal torques according to the formation of the cutting flute. Two types of mini-screws were made, with a thread length of 6.0 mm and a thread length of 3.3 mm. In order to examine the effect of flute formation, the experiment group was divided into a miniscrew test group with flute formation and an experiment group without flute formation. To evaluate the effect of flute formation, two flutes were formed at 180°on the circumference, and at the tip of the mini screw, up to 4 mm for thread length of 6.0 mm and 2.4 mm for thread length of 3.3 mm. A biomechanical test block formed of 2 mm cortical bone and 10 mm cancellous bone was used to eliminate the influence of the difference in cortical bone thickness and bone density according to the insertion site. 1 mm diameter guide hole was drilled on the test block and the mini-screw was placed vertically. Using a 0.1 N·cm precision digital torque gauge, the maximum torque value was recorded at this time by embedding it to the top of the screw under a static load of 1.2 kg and the value when it was removed in the opposite direction. The insertion torque values for the 6.0 mm and 3.3 mm length mini screws were (29.53±1.84) N·cm and (26.84±2.15) N·cm, and the removal torque values are (14.50±1.37) N·cm and (13.15±2.89) N·cm, respectively.There were no statistically significant differences (P>0.05). The flute of 6.0 mm mini-screws had no statistically significant difference in both insertion and removal torque values and increased to (30.13±1.97) N·cm and (18.65±1.10) N·cm (P>0.05). In experiments with 3.3 mm mini-screws, the insertion and removal torque values decreased to (20.99±3.94) N·cm and (11.32±2.03) N·cm, respectively, showing a statistically significant decrease only in the insertion torque values (P<0.05). The insertion and removal torque values of the mini-screw were not significantly increased even when the screw length was doubled, and the flute formation effect was different with the screw length.