• Annals of Clinical Neurophysiology
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• v.23 no.2
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• pp.108-116
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• 2021

Background: Nitrous oxide (N₂O) is used in surgery and dentistry for its anesthetic and analgesic effects. However, neurological and psychiatric manifestations of N₂O abuse have been increasingly reported among Korean adults. The aim of this study was to demonstrate laboratory findings of N₂O abuse in Korean patients. Methods: Patients diagnosed with N₂O-induced neuropathy or myelopathy from August 2018 to December 2019 were enrolled. Their clinical presentations and laboratory and imaging findings were analyzed. Results: Sensory changes and limb weakness were present in nine of the enrolled patients. The laboratory findings revealed that seven patients had high homocysteine levels and five had high methylmalonic acid levels in their blood. Nerve conductions studies indicated that axonal neuropathy was present in four cases and longer F-wave and Hoffman's-reflex latencies were present in two cases. Signal changes in cervical spine imaging occurred in five patients, while two had normal results. Conclusions: Chronic N₂O abuse can cause neurological damage or psychiatric problems. Because N₂O is illegal for recreational use in Korea, patients tend to hide their history of use. Even though the spinal imaging results were normal, clinicians should consider the possibility of N₂O use, and further electrophysiological tests should be applied for precise evaluations.

• The korean journal of orthodontics
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• v.25 no.6 s.53
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• pp.665-674
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• 1995

The purpose of this study is to investigate the cephalometric characteristics of the open-bite patients with DJD of TMJ. The DJD open-bite cases were compared with normal samples and Class II open-bite cases with normal TMJ respectively. Twenty three open-bite patients with bilateral DJD of TMJ($13.9\~35.3$ yens old, Group I) were selected from the Department of Orthodontics, SNUDH. Group ll consisted of thirteen Class II open-bite cases($13.2\~27.4$ years old) with no TMD signs/symtoms and good condylar shapes. Group III samples were the forty eight healthy dental students who have Class I molar relationships with no history of orthodontic treatment, good facial balance and no TMD symptoms($20.0\~26.8$ years old). First, sixty measurements in the lateral cephalometric radiographs and analysis of variance(P<0.05, Scheffe) were used to compare these three groups. The seven measurements showed significant difference(p<0.05) between Group I and Group II. After analysis of variance, six of them were used for the discriminant analysis(Wilks' stepwise analysis) and the discrminant function for Group I/Group II was obtained. The results and conclusions were as follows : In most of the measurments, Group I and Group II showed the same skeletal and dental characteristics. But seven of the sixty measurements(FH-PP angle, SNB, FH-ArGo angle, articulare angle, genial angle, upper gonial angle and Ar-Go length) were significantly different(p<0.05) between Group I and Group II. These differences may be explained by the fact that in DJD cases the mandible rotated backward due to the shortening of the ramus following the degenerative destruction of condylar head and its surrounding structures. The resulting discriminant function was : $D={-0.120X}_1+{0.066X}_2+{0.144X}_3-{0.058X}_4+2000,\;where\;X_1=ArGo\;length(mm),\;X_2=SArGo\;angle(degree),\;X_3=FH-PP\;angle(degree),\;X_4=Gonial\;angle(degree)$. Mean of the group centroids was -0.555 and percent of the 'grouped' cases correctly classified was $88.89\%$.

• The korean journal of orthodontics
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• v.53 no.1
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• pp.3-15
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• 2023

Objective: Body dysmorphic disorder (BDD) is a form of obsessive-compulsive disorder that may be negatively associated with the self-image. It might be associated with orthodontic treatment demand and outcome, and therefore is important. Thus, this study was conducted. Methods: The Yale-Brown Obsessive-Compulsive Scale modified for Body Dysmorphic Disorder (BDD-YBOCS) questionnaire was used in 699 orthodontic patients above 12 years of age (222 males, 477 females), at seven clinics in two cities (2020-2021). BDD diagnosis and severity were calculated based on the first 3 items and all 12 items of the questionnaire. The dental health component of the index of orthodontic treatment need (IOTN-DHC) was assessed by orthodontists. Multivariable and bivariable statistical analyses were performed on ordinal and dichotomized BDD diagnoses to assess potentially associated factors (IOTN-DHC, age, sex, marital status, education level, and previous orthodontic consultation) (α = 0.05). Results: IOTN-DHC scores 1-5 were seen in 13.0%, 39.9%, 29.8%, 12.4%, and 4.9% of patients. Age/sex/marital status/education were not associated with IOTN-DHC (p > 0.05). Based on 3-item questionnaire, 17.02% of patients had BDD (14.02% mild). Based on 12-item questionnaire, 2.86% had BDD. BDD was more prevalent or severer in females, married patients, patients with a previous history of orthodontic consultation, and patients with milder IOTN-DHCs (p < 0.05). Conclusions: IOTNDHC was negatively/slightly associated with BDD in orthodontic patients. Being female and married may increase BDD risk.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.32 no.5
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• pp.473-477
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• 2010

Organized hematoma of the maxillary sinus is a rare, nonneoplastic benign lesion with locally destructive behavior that may mimic a malignancy. Clinically, symptoms do not usually occur while the lesion remains localized to the maxillary sinus. Because there is gradual enlargement of the lesion causing erosion and displacement of the adjacent bony structures, symptoms such as epistaxis, cheek swelling, nasal obstruc-tion, headache, and exophthalmos become manifest. Radiologically, unilateral cases are much more fre-quent than bilateral, and Waters' view shows complete opacity of the expanded maxillary sinus and some masses. CT scan shows a large heterogeneous enhancing mass causing considerable expansion of the max-illary sinus with bony erosion. On MR imaging, the mass usually has a variable signal intensity on T1- and T2- weighted images, ranging from low to high. After contrast administration, discrete areas of enhance-ment are present within the mass. Although the disease is essentially benign and nonneoplastic, differen-tial diagnosis from neoplastic disease including malignancy both clinically and radiologically has been always problematic. Accurate preoperative diagnosis of organized hematoma of the maxillary sinus is important to avoid unnecessary extensive surgery, because this condition is curative with a simple, conservative surgical approach and rarely recur. Organized hematoma of the maxillary sinus should be included in the differential diagnosis when patients have recurrent epistaxis, slow-growing mass of the cheek, nasal obstruction, and expansile mass in the maxillary sinus. A 33-year-old man was referred to the department of oral and maxillofacial surgery with a three-month history of slowly growing painful swelling of the left cheek. The mass of the maxillary sinus was resected by a Caldwell-Luc approach. Histopahtoly showed only a fibous encapsulated organized hematoma. To our knowledge, organized hematoma of the maxillary sinus has not been previously described in the Korean literature of the oral and maxillofacial surgery. We report a case of organized hematoma of the maxillary sinus presenting with an enlarging maxillary sinus mass.

• Anatomy and Cell Biology
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• v.55 no.1
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• pp.72-78
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• 2022

The purpose of this study was to analyze the accuracy of intra oral scanner (IOS) to confirm the applicability of IOS for the recording and analysis of tooth morphology in forensics. The less damaged mandible specimen with many teeth remaining was scanned three times using three types of intraoral scanners (CS3600, i500, and Trios3). For quantitative comparisons of the scanned images produced by these intraoral scanners, root mean square (RMS) values were computed using a three-dimensional analysis program and a one-way ANOVA was conducted with Tukey HSD (honestly significant difference) as a post-hoc analysis (α=0.05). The repeatability of the full scan data was highest with the i500 (0.14±0.03 mm), and the post-hoc analysis confirmed significant differences between the CS3600 and the i500 outcomes (P-value=0.003). The repeatability of the partial scan data for the teeth in the mandible was highest with the i500 (0.08±0.02 mm), and the post-hoc analysis confirmed significant differences between the CS3600 and the i500 (P-value=0.016). The precision of the full scan data was highest with the i500 (0.16±0.01 mm) but the differences were not statistically significant (P-value=0.091). Meanwhile, the precision of the partial scan data for the teeth in the mandible was highest with the Trios3 (0.22±0.02 mm), but the differences were not statistically significant (P-value=0.762). Considering that the scanning of other areas of the oral cavity in addition to the teeth is important in forensic odontology, the i500 scanner appears to be the most appropriate intraoral scanner for human identification. However, as the scope of oral scanning is generally limited to teeth in the practice of dentistry, additional discussions of how to apply the IOS in forensic odontology are needed. Ultimately, the results here can contribute to the overall discussion of the forensic applicability dental data produced by intraoral scanners.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.1
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• pp.165-168
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• 2012

Objectives: This study aimed to assess the level of knowledge of oral cancer and its associated factors among university students in Malaysia. Methods: A cross sectional study was conducted among 200 university students in Malaysia. A self administered questionnaire was used to collect data. It included questions on sociodemographic data, awareness and knowledge of oral cancer. Results: Mean age of the respondents was $21.5{\pm}2.5$ and the age ranged from 18 to 27 years. The majority of the respondents were aware of oral cancer (92.0%) and recognized the followings as signs and symptoms of oral cancer: ulcer and oral bleeding (71.0%), followed by swelling (61.5%). A satisfactory knowledge was observed on the following risk factors; smoking (95.5%), poor oral hygiene (90.5%), family history (90.0%), alcohol (84.5%) and poor fitting dentures (83.0%). However, unsatisfactory knowledge was observed about hot/spicy food (46.5%), obesity (36.0%), old age (31.5%), dietary factor (29.0%) and smokeless tobacco (25.5%). Knowledge of oral cancer was associated significantly with age (p<0.01), year of study (p<0.01) and course of study (p<0.01). Conclusion: Instead of satisfactory awareness and knowledge of oral cancer and its clinical presentations, inadequate knowledge was observed about its risk factors. There is a need to introduce oral cancer education among university students.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.46 no.3
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• pp.174-182
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• 2020

Objectives: Joint injuries frequently lead to progressive joint degeneration that causes articular disc derangement, joint inflammation, and osteoarthritis. Such arthropathies that arise after trauma are defined as post-traumatic arthritis (PTA). Although PTA is well recognized in knee and elbow joints, PTA in the temporomandibular joint (TMJ) has not been clearly defined. Interestingly, patients experiencing head and neck trauma without direct jaw fracture have displayed TMJ disease symptoms; however, definitive diagnosis and treatment options are not available. This study will analyze clinical aspects of PTA in TMJ and their treatment outcomes after joint arthrocentesis and lavage. Materials and Methods: Twenty patients with history of trauma to the head and neck especially without jaw fracture were retrospectively studied. Those patients developed TMJ disease symptoms and were diagnosed by computed tomography or magnetic resonance imaging. To decrease TMJ discomfort, arthrocentesis and lavage with or without conservative therapy were applied, and efficacy was evaluated by amount of mouth opening and pain scale. Statistical differences between pre- and post-treatment values were evaluated by Wilcoxon signed-rank test. Results: Patient age varied widely between 20 and 80 years, and causes of trauma were diverse. Duration of disease onset was measured as 508 post-trauma days, and 85% of the patients sought clinic visit within 2 years after trauma. In addition, 85% of the patients showed TMJ disc derangement without reduction, and osteoarthritis was accompanied at the traumatized side or at both sides in 40% of the patients. After arthrocentesis or lavage, maximal mouth opening was significantly increased (28-44 mm on average, P<0.001) and pain scale was dramatically decreased (7.8-3.5 of 10, P<0.001); however, concomitant conservative therapy showed no difference in treatment outcome. Conclusion: The results of this study clarify the disease identity of PTA in TMJ and suggest early diagnosis and treatment options to manage PTA in TMJ.

• Journal of dental hygiene science
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• v.21 no.1
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• pp.8-18
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• 2021

The purpose of this study is to provide the general history of fostering dentists in Japan and introducing their new roles. This research was conducted based on the government policy report on dentists and the information published by each educational institution. Based on the collected data, the official websites were used to represent the latest statistics of the institutions. The number of dentists in Japan has increased. The government established the National Examination for Dentists to guarantee the quality of dentists. After the standards for developing questions for the national examination were established in 1985, the contents of the examination have been appropriately improved by revising the standards every four years. This improvement has required dental students to study a variety of subjects for six years at dental school. Since dentists in Japan are required to respond to various demands from the nation; the Model Core Curriculum for Dental Education was developed to teach medical ethics and abilities to ensure that dentists conduct themselves professionally. Recently, the roles of dentists have been changing in Japan. When providing dental services to older patients over the age of 65, dentists and other dental professions focus on maintaining oral functions, such as saliva secretion, bite force, tongue movement, and masticatory/swallowing functions. However, oral function-related services for children are different. In addition to providing essential dental services, dental practitioners also provide special treatment, such as oral muscle training, myofunctional therapy, health guidance, and space retainers to the child patients with developmental insufficiency in oral functions. Dentistry in Japan has undergone numerous changes over the years and has continued to offer high-quality dental health services. Thus, information gained from the Japanese experience may be helpful to dental professions in other developed countries for planning oral health measures.

• Corrosion Science and Technology
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• v.2 no.3
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• pp.117-126
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• 2003

Due to excellent corrosion resistance and mechanical properties, austenitic stainless steel is widely used as the material for chemical plants. nuclear power plants, and food processing facilities. But, the zone affected by heat in the range of 400 to $800^{\circ}C$ during welding loses corrosion resistance and tensile strength since Cr-carbide precipitation like $Cr_{23}C_6$ forms at the grain boundary and thereby takes place the intergranular corrosion. In this study, AISI 304 stainless steel with the added Nb of 0.3 to 0.7 wt% was solutionized at $1050^{\circ}C$ and sensitized at $650^{\circ}C$. Specimen was welded by MIG. The phase and the microstructure of the specimens were examined by an optical microscope, a scanning electron microscope, and a x-ray diffractometer. The corrosion characteristics of specimens were tested by electrolytic etching and by double loop electrochemical potentiokinetic reactivation method(EPR) in the mixed solution of 0.5M $H_2SO_4$ + 0.01M KSCN. The melting zone had dendritic structure constituted of austenitic phase and $\delta$-ferrite phase. Cr carbide at the matrix did not appear, as Nb content increased. At the grain boundaries of the heat affected zone, the precipitates decreased and the twins appeared. The hardness increased, as Nb content increased. The hardness was highest in the order of the heat affected zone>melted zone>matrix. According to EPR curve, as the Nb content decreased, the reactivation current density(Ir) and the activation current density(la) were highest in the order of the melted zone

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.18
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• pp.8473-8477
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• 2016

Background: High risk human papilloma virus (HPV) types 16 and 18 have been proven as central causes of cervical cancer and safety and immunogenicity of HPV vaccines are sufficiently established. Knowledge and practices of HPV vaccination among medical and paramedical students is vital as these may strongly determine intention to recommend vaccination to others in the future. The present study was therefore undertaken to assess the knowledge, attitude and practices regarding cervical cancer screening and HPV vaccination among medical and paramedical students and to analyze factors influencing them. Materials and Methods: The present cross sectional study, conducted in a tertiary care teaching hospital in south India, included undergraduate students aged 18 years and above, belonging to medical, dental and nursing streams, after informed written consent. Results: Out of 957 participants, only 430 (44.9%) displayed good knowledge and only 65 (6.8%) had received HPV vaccination. Among the unvaccinated, 433 (48.54%), were not willing to take the vaccine. Concerns regarding the efficacy (30.5%), safety (26.1%) and cost of the vaccine (21.7%) were responsible for this. Age, gender, family history of malignancy and mother's education had no influence on knowledge. Compared to medical students, nursing students had better knowledge (OR-1.49, 95% CI 0.96 to 2.3, p = 0.072) and students of dentistry had poor knowledge (OR-0.50 95% CI 0.36 to 0.70, p<0.001). Conclusions: The knowledge and uptake of HPV vaccination among medical and paramedical students in India is poor. Targeted health education interventions may have huge positive impact not only on the acceptance of vaccination among them, but also on their intention to recommend the vaccine in future.