The post core system has been used for reconstructon of severely damaged crown by caries or trauma.But problems such as crown exfoliation,post core fracture and root fracture have been reported. Ideal mechanical properties of the post require high fracture strength,high elastic limit and high resistance against fatigue and corrosion.Modulus of elasticity of the post should be similar with that of dentine.Low hardness is also required for the convenience of post removal in failure.Furthermore, the post itself must be translucent for the esthetical purpose.Several types of the post have been developed to satisfy the criteria above mentioned. The purpose of this study was to find out the mechanical properties of quartz fiber post by comparing with those of gold post and zirconia post. The results of this study were as follows : 1.Maximal fracture strength and stiffness of quartz fiber post were similar with those of gold post and zirconia post. 2.Young's modulus and hardness of quartz fiber post were lower than those of gold post and zirconia post. Mechanical property of quartz fiber post against post fracture was similar with that of gold post and zirconia post.Mechanical property of quartz fiber post against root fracture was higher than that of gold post and zirconia post.Quartz fiber post could be removed easily due to low hardness.
Crowns ; Elastic Modulus ; Elasticity ; Fatigue ; Hardness ; Quartz*

This study aimed to investigate parents’ and dentists’ perceptions of the national oral health screening for infants and children (OHS), and evaluate the dentists’ accuracy of analyzing the results of OHS. A questionnaire survey was conducted, face-to-face or online, for 90 parents of children who received OHS in the Department of Pediatric Dentistry at Yonsei University Dental Hospital and 100 dentists working at local clinic or university dental hospital from May to October 2021. Most parents and dentists were aware of the importance of OHS, and approximately 96.7% of parents were satisfied with OHS. The requirements of parents and dentists about OHS were different. The reasons for having difficulties in explaining parents after OHS and the opinions on appropriate period and number of OHS were disagreed between pediatric dentists and general dentists. Regardless of dentists’ major, work experience, elapsed period after taking online education program, the accuracy of the examination result was low. In this study, various opinions of parents and dentists on OHS were collected. Efforts should be made to enhance the oral health of infants and children by considering the requirements of parents and dentists and improving the accuracy of examination results.

Facioscapulohumeral muscular dystrophy (FSHD) is a genetically trarlsmitted benign muscular dystrophy which has autosomal dominant inheritance pattern. It starts anytime within the first 30 years of life, and usually involves the face and shoulder girdle, and finally the pelvic muscles with very slow progression. Authors-report a fanily consisting of a father, two sons and one daughter, who had suffered from exertional dyspnea, weakness of facial muscle and winged scapulae, all wlth a slow progressive course. Two of these patients were biopsied arld confirmed light microscopically and electron microsopically.
Dyspnea ; Facial Muscles ; Fathers ; Humans ; Inheritance Patterns ; Muscles ; Muscular Dystrophies ; Muscular Dystrophy, Facioscapulohumeral* ; Nuclear Family ; Scapula ; Shoulder

Precocious puberty (PP) is defined as the early development of secondary sexual characteristics (before the ages of 8 years in girls and 9 years in boys). The aim of this study is to identify characteristics of the dental maturity in girls with PP that discriminate them from normal healthy girls. This study included 99 girls aged 6 - 8 years with PP and 99 girls without past medical history of same chronological age (control group). The study was performed on 198 panoramic radiographs (99 PP girls, 99 control group girls). Demirjian method was used to evaluate the panoramic radiographs and determine dental maturity. Difference in dental maturity score and tooth formation stages between the two groups were analyzed. The PP group showed significant higher maturity score than control group. Among mandibular teeth, mandibular 2nd premolar and 2nd molar were significantly more mature in the PP group than control group. Logistic regression analysis showed that mandibular 2nd molar was only significant predictor for PP girls.

This study intended to evaluate noise level of dental handpieces and the effects of noise cancelling devices. An ear model was designed to measure the level of the noise delivered to the inner ear during dental handpiece operation. The level of noise was measured in various conditions using the ear model and the portable noise meter. Noise level was measured again after applying of 4 different noise cancelling devices to the model ear.
The noise level of dental handpieces was 82.5 - 84.4 dB. When 4 types of noise canceling devices were applied, the noise level reduced to 67.4 - 73.8 dB. All 4 devices had statistically significant effect in reducing the noise of the handpiece.
Considering the intensity and exposure time, noise in dental clinics can cause hearing damage to dentists. For protection from the risk of occupational hearing damages, noise canceling devices can be recommended.

The aim of this study was to evaluate the accuracy of 3 different automatic landmark identification programs on lateral cephalgrams and the clinical acceptability in pediatric dentistry.
Sixty digital cephalometric radiographs of 7 to 12 years old healthy children were randomly selected. Fourteen landmarks were chosen for assessment and the mean of 3 measurements of each landmark by a single examiner was defined as the baseline landmarks. The mean difference between an automatically identified landmark and the baseline landmark was measured for each landmark on each image.
The total mean difference of 3 automatic programs compared to the baseline landmarks were 2.53 ± 1.63 mm. Errors among 3 programs were not significantly different for 12 of 14 landmarks except Orbitale and Gonion. The automatic landmark identification programs showed significant higher mean detection errors than the manual method. The programs couldn’t be used as the 1st tool to replace human examiners. But considering short consuming time, these results indicate that all 3 programs have sufficient validity to be used in pediatric dental clinic.

Retina, a part of CNS, has served valuable and accessible tissue for elucidating the cellular properties of neurons and glia due to its similarity to brain. Unlike mammalian counterpart, avian retina is devoid of vessels and astrocytes. However little is known about glial reaction to neuronal injuries in this species. Therefore, this study was performed to investigate the microglial responses in the quail retina following neuronal injuries. The retinae from normal and optic nerve transected adult quails were studied immunohistochemically with anti-QH1, a marker known to be specific for microglia. In the normal retina, QH1-labeled microglial cells displayed typical feature of ramified (resting) form and were localized mainly in the inner plexiform layer. After optic nerve transection (ONT) morphology of microglial cells changed from the ramified to the amoeboid form. This feature of microglial cells maintained throughout the post operational periods until 28 days after ONT. Particularly, at 14 and 21 days after ONT amoeboid microglia displayed cell bodies with stout and bushy processes, suggesting active phagocytosis. The distribution pattern of microglia also changed in accord to ganglion cell degeneration: they gradually moved to layers of ganglion cells and optic nerve fibers where ganglion cell bodies and axons were under degeneration. This change of microglial distribution was most prominent at 14 days of ONT. The result of this study is generally consistent with that reported in mammalian counterpart and this similarity between the avascular avian retina and the vascularized mammalian counterpart suggests that processes of microglial activation, such as migration and phagocytosis, can occur in the vessel-free CNS tissue.
Adult ; Astrocytes ; Axons ; Brain ; Ganglion Cysts ; Humans ; Microglia* ; Neuroglia ; Neurons ; Optic Nerve Injuries* ; Optic Nerve* ; Phagocytosis ; Quail ; Retina ; Retinaldehyde*

This paper describes the potential oral complications in preterm infants who have undergone orotracheal intubation. Neonatal intubation may have adverse effects on the developing deciduous teeth, oral soft tissues, and even the permanent teeth. However, endotracheal intubation may be essential for the survival of premature infants, owing to incomplete tracheal development. Excessive pressure to the oral tissue must be avoided, in cases where orotracheal intubation is inevitable. Moreover, the potential oral complications must be considered when neonatal intubation is performed for the patient's survival, and subsequent reevaluation and proper oral health care are needed.
Humans ; Infant, Newborn ; Infant, Premature ; Intubation ; Intubation, Intratracheal ; Oral Health ; Tooth ; Tooth, Deciduous

Despite the modern advance in effective chemotherapy, gastrointestinal tuberculosis is considered to be relatively frequent in developing countries. The ileocecal region is the most common site of intestinal tuberculosis and duodenal involvement is rare. The isolated duodenal tuberculosis are reported 9 cases in Korea. The symptoms and signs of gastrointestinal tuberculosis are nonspecific and vague. In the absence of pulmonary tuberculosis, the diagnosis may be difficult. Pain and vomiting are common symptoms of duodenal tuberculosis. Patients may present with upper gastrointestinal bleeding. Therefore, tuberculosis should be considered in the differential diagnosis of gastrointestinal bleeding. We herein report a case of duodenal tuberculosis presenting as hematemesis and necessitating hospitalization. After anti-tuberculosis therapy, we have confirmed the healing of the lesion by the follow-up endoscopy, and review the current literature.
Developing Countries ; Diagnosis ; Diagnosis, Differential ; Drug Therapy ; Endoscopy ; Follow-Up Studies ; Hematemesis* ; Hemorrhage ; Hospitalization ; Humans ; Korea ; Tuberculosis* ; Tuberculosis, Gastrointestinal ; Tuberculosis, Pulmonary ; Vomiting

OBJECTIVES: The purpose of this study was to estimate the number of serious and persistent mentally ill patients in Korea. METHODS: Study populations were recruited from medical insurance data of two district areas one rural and the other urban areas. Subjects were all mentally ill who had ever visited any hospital in 1993 and were diagnosed as having psychosis, personality disorder and drug abuse. We conducted a home visiting survey applying semi-structured diagnostic interview, assessing the level of social adjustment with Strauss-Carpenter Scale, and past psychiatric history by the trained researchers, in October and November, 1994. RESULTS: According to diagnostic assessment, schizophrenic patients constituted the major portion(61.1%) of study subjects. The distribution of occupational functions and social contacts was variable according to diagnosis. Most schizophrenic patients were unemployed or worked less than 6 months in the previous year(67.2%), and showed poor social contact(72.3%). But affective disorder patients were relatively independent in job maintenance and social relationship. Alcoholic patients lay between those of schizophrenic and affective disorder groups. It was estimated that about 87,000 adult Koreans were suffering from chronic mental disorders which seriously interfere with their daily life. CONCLUSIONS: Serious and persistent mentally ill patients were common in Korea. Community support program should be provided for them.
Adult ; Alcoholics ; Community Psychiatry ; Surveys and Questionnaires* ; Diagnosis ; Epidemiology ; House Calls ; Humans ; Insurance ; Korea* ; Mental Disorders ; Mentally Ill Persons* ; Mood Disorders ; Personality Disorders ; Psychotic Disorders ; Schizophrenia ; Social Adjustment ; Substance-Related Disorders