• Journal of Periodontal and Implant Science
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• v.24 no.1
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• pp.165-177
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• 1994

To investigate the depth of the root concavity and root surface area of the maxillary first premolar, 40 maxillary first premolars were used. All the teeth which extracted because of advanced periodontal disease and orthodontic treatment procedure, were sectioned every 1.5mm from cementoenameljunction to the apex with hard tissue microtome. Each sectioned root was taken photograph with slide film, and projected for measuring with a calibrated digital Curvi-Meter. The root surface area, percentage of the RSA and the linear variation of the RSA were calibrated for each 1.5mm section. Linear variation of the depth of root concavity was measured on mesial and distal root surface for each section using computer-aided digitizer. The results were as follows. 1. The total mean root length of maxillary first premolar was 13.48mm. Mean buccal root length of 2-rooted tooth was 12.59mm, mean palatal root length was 12.73mm, and mean root length of single rooted tooth was 13.78mm. 2. The total mean root surface area of maxillary first premolar was $194.17mm^2$, mean root surface area for 2-rooted tooth was $205.97mm^2$ and mean root surface area for single rooted tooth was $188.49mm^2$. 3. It was 59.93% of the total root surface area that the area from CEJ to coronal 6mm. And, the coronal half of the root length accounted for approximately 71.76% of the total root surface area. 4. Most deepest concavity of the mesial root surface was 0.65mm at apical 3.0mm, 4.5mm level in maxillary first premolar. And, that of the distal root surface was 0.37mm at apical 4.5mm level. 5. All of the maxillary first premolar had mesial root surface concavity. This mesial root surface concavity appeared to be more pronounced in 2-rooted tooth than single rooted tooth.

• Journal of Chest Surgery
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• v.23 no.3
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• pp.532-536
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• 1990

We experienced surgical correction of 2 cases of discrete membranous subaortic stenosis. Case 1 was 19 years old male patient. His complaints were fatigue, exertional dyspnea, syncope and angina for 8 years. Ejection. systolic murmur was heard at the second right intercostal space and diastolic murmur was heard at the apex. A thrill was palpated over the second right intercostal space and area of the carotid artery. 2-D echo, cardiac cath and left ventriculogram revealed discrete membranous subaortic stenosis and VSD. Complete excision of discrete membrane without mymectomy was done. VSD was closed with dacron patch and aortic valve was replaced with St. Jude medical valve. Case 11 was 16 years old female whose complaints were exertional dyspnea and syncope. Ejection systolic murmur was heard at second right intercostal space, but diastolic murmur was not heard. A thrill was palpated over the second right intercostal space and the area of carotid artery. 2-D echo, cardiac cath and left ventriculogram revealed discrete membranous subaortic stenosis. Complete excision of fibrous tissue and myotomy were made and aortic valve was replaced with St. Jude medical valve. Operative finding was followed: both aortic valves showed deformity of leaflets. Subaortic region had a thickened central fibrous body from which the ridge protruded. Both patient`s postoperative course were uneventful and short-term follow-up results were good except soft systolic murmur at the aortic area.

• Restorative Dentistry and Endodontics
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• v.42 no.4
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• pp.290-300
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• 2017

Objectives: This study investigated the removal efficacy and cytotoxicity of a newly developed calcium hydroxide paste (cleaniCal, Maruchi) using N-2-methyl-pyrrolidone (NMP) as a vehicle in comparison with ApexCal (Ivoclar Vivadent) and Calcipex II (Nishika), which use different vehicles such as polyethylene glycol and propylene glycol, respectively. Materials and Methods: Thirty maxillary premolars with oval-shaped canals were divided into 3 groups and the teeth were filled with one of the pastes. After removal of the paste, micro-computed tomographic (${\mu}$-CT) imaging was obtained to assess the volume of residual paste in the root canal of each tooth. The teeth were then split longitudinally and the area of the paste-coated surface was evaluated by stereomicroscopy. The cytotoxicity of each product was assessed using an agar overlay assay. The effect of each vehicle on cell viability was evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The data were analyzed using one-way analysis of variance and Tukey's tests to detect any significance (p < 0.05). Results: In the ${\mu}$-CT and stereomicroscopic analysis, cleaniCal exhibited less remnants of medicament than ApexCal and Calcipex. cleaniCal showed a higher cytotoxicity than the other pastes in the agar overlay assay. Furthermore, NMP exhibited lower cell viability compared to the other vehicles. Conclusions: cleaniCal showed better removal efficacy compared to the other products. However, clinicians should be aware of the higher cytotoxicity of the NMP-based material and consider its possible adverse effects on periradicular tissue when it is overfilled.

• The Journal of Korean Academy of Prosthodontics
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• v.33 no.3
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• pp.517-538
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• 1995

Dental implantation is a method restoring missing teeth, especially in the case of severely resorbed edentulous patient. But the direct contact between bone and implant surface, induces stress concentration to the bone and eventually becomes a cause. The purpose of this study was to compare the stress distribution patterns between following two cylindrical implant models. One group has implant apex located in the inferior cortical bone and the other in the cancellous bone. Anterior edentulous mandible was modeled with two dimensional 953,878 nodes, 995,918 elements and compared the deflection and stress distribution under the 70 N,4 load cases for 26 models having variant mandibular height and length. The result were as follows; 1. The stress concentration was more affected by the height of the mandible than implant length. 2. Bicortication mitigates the stress of upper cortical and cancellous bone area at the same height of the mandible 3. Perforation of the inferior mandibular cortex significant stress concentration. 4. Stud type porstheses induced less stress concentration to the cortical and cancellous bone than bar type prostheses. 5. Stress of implant apex for stud type was larger than that of bar type.

• The Journal of Korean Academy of Prosthodontics
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• v.33 no.2
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• pp.241-268
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• 1995

Splint therapy, the immobilization of teeth, has been done for patient's masticatory comforts and an adjunctive aid in periodontal therapy. Mandibular premolars are frequently splinted in many distal extension removable partial denture cases. But splinting is an extensive restoration that may not be conservative of tooth structure and may prove to be quite costly to the patient. The two dimensional finite element analysis method was used to determine the magnitude and mode of distribution of the stresses of the periodontal ligament and supporting alveolar bone when abutments with different periodontal supports were splinted and distal-extension removable partial denture was subjected to different loading schemes. The results were as follows : 1. When abutments were splinted, stresses moved from apico-distal to apico-mesial of terminal abutment on a vertical force and from disto-alveolar crest to apex on a distally directed force. But stresses were generally diminished on a mesially directed force. 2. As vertical bone loss was proceeding, most of stresses were transmitted to residual ridge and the rest of stresses were concentrated on apex of distal abutment. But these apical stresses were minimized when abutments were splinted. 3. As mesially inclined bone loss was proceeding, it seemed to be dangerous that many stresses were concentrated on the distal alveolar crest, especially in the distally directed load case. Abutments splinting decreased the alveolar crestal stresses but not enough. 4. For all vertical stresses were effectively decreased on splinting, stresses were concentrated as highly on apico-mesial area of distal abutment in distally directed load cases as the distal inclination of bone level was severe. 5. The directions and magnitudes of abutment movements were decreased with teeth splinting.

• Journal of Ecology and Environment
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• v.35 no.3
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• pp.177-188
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• 2012

We analyzed crown development in Aucuba japonica Thunb. var. japonica resulting from the responses of phytoelements to habitat light conditions over a long period of time. Over the years, the degree of extension unit (EU) dimorphism and the degree of anisophylly were higher under shaded conditions than in brighter conditions. An overall temporally increasing pattern in the degree of EU dimorphism was found while no clear-cut trend was found in the case of anisophylly. EU length and number of leaves per EU co-varied in a spatio-temporal context. The number of terminal buds and their sizes acted as the key initiators of morphological differences of phytoelements which were further amplified following bud break. Leaf area density was displayed mostly in the apex peripheral layer of the crown and the apex layer received most of the incident light. There was a tradeoff between annual leaf production and mean leaf size. Depending on the heterogeneity of irradiance level within a crown, correlative growth inhibition caused higher EU mortality at brighter sites. Due to high mortality, shorter EUs had a mere role in the construction of structural framework of the crown except for the formation of some gaps. There was a strong convergence of EU dimorphism, anisophylly, EU extension growth and variations in leaf size towards formation of functional crown to reduce potential self-shading. Depending on the irradiance level, Aucuba japonica Thunb. var. japonica showed two different modes of crown expansion. At the brighter sites, individual crown expansion was progressive while at the darker sites, individual crown expanded in a diminishing manner and maintained a stable size. A plant's "growth diminishing phase" appeared earlier at shaded sites than brighter sites.

• Education of Primary School Mathematics
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• v.19 no.2
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• pp.113-125
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• 2016

The concept and measuring activities of the height of figures are essential to find the areas or volumes of the corresponding figures. For plane figures, the height of a triangle is defined to be the line segment from a vertex that is perpendicular to the opposite side of the triangle, whereas the height of a parallelogram(trapezoid) is defined to be the distance between two parallel sides. For the solid figures, the height of a prism is defined to be the distance of two parallel bases, whereas the height of a pyramid is defined to be the perpendicular distance from the apex to the base. In addition, the height of a cone is defined to be the length of the line segment from the apex that is perpendicular to the base and the height of a cylinder is defined to be the length of the line segment that is perpendicular to two parallel bases. In this study, we discuss some pedagogical problems on the concepts and measuring activities of the height of figures to provide alternative activities and suggest their educational implications from a teaching and learning point of view.

• Restorative Dentistry and Endodontics
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• v.14 no.1
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• pp.173-177
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• 1989

As widely known major cause of tooth discoloration is red blood cell in dentinal tubules after tooth trauma and extirpation. Hemoglobin in the red cells easily conbine with hydrogen sulfide and change natural tooth color into dark brown. To confirm and compare the effect of bleaching agents test material was made as fellows: No. 40 paper points were soaked in blood and put into the oven for 24 hours to dry. Dried paper points were again soaked in diluted yolk by distilled water for a minute and kept the points for a week to get fully sulfide. Hydrogen peroxide (25%), Sodium hypochlorite (2%), Sodium hyposulfate (2%), Sodium perborate and mixture of Hydrogen peroxide (25%) and Sodium perborate were employed as bleaching agents. About 0.2ml of each medicaments were put into the small test tubes and blood soaked paper points were gently placed vertically with the apex downward and kept 24 hours in the oven ($37^{\circ}C$). Every 24 hours the medicaments were renewed at 24 and 48 hours. Following are the results of the study: 1. Significant bleaching effect was found on the case of hydrogen peroxide (25%) after 24 hours. The area above 2mm from apex also fully bleached after 48 hours. 2. A mixture of hydrogen peroxide and sodium perborate treated case showed moderate effect at 24 hours and significant effect at 48 hours. High portion of the point (above 2mm) was bleached satisfactory at 72 hours. 3. The effect of sodium perborate at 48 hours showed moderate and significant at 72 hours. 4. Sodium hypochlorite and sodium hyposulfate were weak agent in bleaching. At 72 hours case revealed moderate effect and influenced on high portion of the point very weak effect.

• Applied Microscopy
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• v.5 no.1
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• pp.9-19
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• 1975

In order to clarify the mecahnism of histological barriers to pathogens of witches' broom diseased in sweet potatoes, this experiment has been conducted to observe the relationship between pathological characters and the transfer of mycoplasmae in the shoot apex. The material used the experiment is the sweet potato (Ipomoea batatas (L.) Lamm. Suwon 147). In the experiment regarding of mycoplasmae, the upper limit zone of transfer of mycoplasmae is examined by way of the process of free stock and the shoot apex of a infected part in nature, observed in the culture of each part of the diseased plant which is cut to a certain length. The pathological change pattern of tissues infected with mycoplasmae has been observed under the light and electron microscopes. As a result of this experiment, the following conclusion was arrived at. 1. It has been ascertained that the mycoplasmae are not existent in a promeristem and primary meristem zone from the meristem dome, and is existent in the lower part of the vascular differentiation zone, after which differential tissues the mycoplasmae become progressively enlarged, and before which undifferential tissues it become progressively immatured and diminished in size. 2. It can be suggested that mycoplasmae may not be existed in the shoot meristem, be cause the passing structures such as sieve area and plasmodesma which can be pass ed immatured mycoplasmae is undifferentiated. 3. In the tissue culture, free stock can be obtained in the zone between 1.0-1.5mm of the shoot apex, while it cannot in the 2.0-3.0mm zone, because of infection by mycoplasmae. It is suggested that immature mycoplasmae may be diffused according to temperature ($28{\pm}1^{\circ}C$) in tissue culture process.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.42 no.5
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• pp.307-314
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• 2016

We report a case of retiform hemangioendothelioma (RH) located in the infratemporal fossa and buccal area in a 13-year-old Korean boy. The tumor originated from the sphenoid bone of the infratemporal fossa area and spread into the cavernous sinus, orbital apex, and retro-nasal area with bone destruction of the pterygoid process. Tumor resection was conducted via Le Fort I osteotomy and partial maxillectomy to approach the infratemporal fossa and retro-nasal area. The diagnosis of RH was confirmed after surgery. In the presented patient, surgical excision was incomplete, and close follow-up was performed. There was no evidence of expansion or metastasis of the residual tumor in the 8 years after surgery. In cases of residual RH with low likelihood of expansion and metastasis, even though RH is an intermediate malignancy, close follow-up can be the appropriate treatment choice over additional aggressive therapy. To date, 29 papers and 48 RH cases have been reported, including this case. This case is the second reported RH case presenting as primary bone tumor and the first case originating in the oromaxillofacial area.