• Journal of dental hygiene science
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• v.14 no.3
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• pp.390-396
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• 2014

The purpose of this study was to examine the size, form of dental arch and occlusion type in college students in our country and the relationship of the factors. The subjects in this study were 210 selected dental hygiene students. The collected data were analyzed by a statistical package PASW 18.0. When their size, form and occlusion of dental arch were analyzed, the inter-canine width of the maxillary was 34.38 mm, and the inter-first molar width was 52.05 mm. The canine depth was 8.60 mm, and the first molar depth was 28.69 mm. As for the mandibular, the inter-canine width was 26.42 mm, and the inter-first molar width was 44.83 mm. The canine depth was 5.54 mm, and the first molar depth was 24.38 mm. Concerning the form of dental arch, the percentage of normal dental arch in the maxillary stood at 29.0, and that of crowding stood at 60.5. The percentage of spacing stood at 10.5. In the case of the mandibular, the percentage of normal dental arch stood at 29.0; crowding, 55.7; and spacing, 15.2. In relation to occlusion, the percentage of normal occlusion stood at 16.7. As to malocclusion, class I that accounted for 55.7 was most common, and class II and class III respectively accounted for 20.5 and 7.1. When the size of dental arch was compared according to the form and occlusion of it, dental arch was largest (45.95 mm) in size when the form of dental arch in the inter-first molar width of the mandibular was spacing. The size of dental arch was 44.73 mm when its form in the same region was normal, and that was 44.58 mm when its form in the same region was crowding (p=0.032). Regarding the relationship between the form and occlusion of dental arch, crowding was most common when there were class I, II and III of malocclusion both in the maxillary and mandibular.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.41
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• pp.33.1-33.7
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• 2019

Background: The concept of the ideal morphology for the alveolar bone form is an important element to reconstruct or restore the in maximizing esthetic profile and functional alveolar bone restoration. The purpose of this preliminary study is to evaluate the normal alveolar bone structure to provide the standard reference and guide template for use in diagnosing for implant placement, determining the correct amount of bone augmentation in actual clinical practice and producing prostheses based on three-dimensional imaging assessment of alveolar bone. Methods: This study was included 11 men and 11 women (average age, 22.6 and 24.5 years, respectively) selected from among 127 patients. The horizontal widths of alveolar bone of maxilla and mandible were measured at the crestal, mid-root, and root apex level on MDCT (multi-detector computed tomography) images reconstructed by medical imaging software. In addition, tooth dimensions of the central incisors, canines, second premolars, and first molars of maxilla and mandible, including the horizontal width of the interdental alveolar bone crest, were also measured and statistically analyzed. Results: The horizontal alveolar bone width of the palatal side of maxilla showed a distinct increment from the alveolar bone crest to the apical region in both anterior and posterior areas. The average widths of the maxillary alveolar ridge were as follows: central incisor, 7.43 mm; canine, 8.91 mm; second premolar, 9.57 mm; and first molar, 12.38 mm. The average widths of the mandibular alveolar ridge were as follows: central incisor, 6.21 mm; canine, 8.55 mm; second premolar, 8.45 mm; and first molar, 10.02 mm. In the buccal side, the alveolar bone width was not increased from the crest to the apical region. The horizontal alveolar bone width of an apical and mandibular border region was thinner than at the mid-root level. Conclusions: The results of the preliminary study are useful as a clinical guideline when determining dental implant diameter and position. And also, these measurements can also be useful during the production of prefabricated membranes and customized alveolar bone scaffolds.

• Journal of Periodontal and Implant Science
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• v.36 no.1
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• pp.147-154
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• 2006

Surgical intervention in the posterior maxillary region requires detailed knowledge of maxillary sinus anatomy and the possible anatomical variations. This study evaluated the incidence, location of maxillary sinus septa by using radiographic (panoramic radiography and computed tomography) findings and comparison of panoramic radography with CT in antral anatomical variation. This study was based on data from 70 sinuses in partial dentate maxilla. The sample consisted of 61 patients(25 women and 36 men, with ages ranging between 19 and 77 years and a mean age of $49.4{\pm}11.3$ years) who were being treatment-planned to receive implant-supported restorations. First, the panoramic images were examined for the presence of antral septa by radiologist and examiner who don't know about CT findings. And incidence of antral septa was evaluated using an axial plane of CT image. The incidence of septa was compared between panoramic radiography and CT. The accuracy of the incidence was compared between radiologists and dentists. A total of 20 septa were found in 70 sinuses on CT image and the prevalence of one or more septa per sinus was found to be 28.6%. The assumed incidence of septa on panoramic radiography was $27.6%{\pm}2.2%$ in radiologist and $31.9%{\pm}5.8%$ in dentists. Erroneous diagnosis rate was 11.42% in radiologist and 15.96% in dentists. 40% of antral septa were located in the anterior(premolar) region, 30% of septa were located in the middle(first molar) and posterior(second molar) region separately. Prior to implant placement, it seems appropriate to consider panoramic radiography as a standard radiographic examination and periapical radiographs may be used to complete the findings in regions not sharply depicted in the panoramic radiograph. And cross-sectional imaging should be used in sites with severe bone loss and close proximity of the maxillary sinus.

• Journal of the Korean Chemical Society
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• v.49 no.6
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• pp.560-566
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• 2005

Sintered ceramic samples of pure and some copper doped layered sodium lithium tri-titanate ($Na_{1.9}Li_{0.1}Ti_{3-X}Cu_XO_{7-X}$) materials with different dopant molar percentages (0.0$Cu^{2+}$ at $Ti^{4+}$ sites in the lattice is proposed in this paper. Furthermore, three distinct regions have been identified in log(${\sigma}_{d.c.}T$) versus 1000/T plots. The lowest temperature region is attributed to electronic hopping conduction(polaron) for all copper doped derivatives and ionic conduction for lithium substituted $Na_2Ti_3O_7$.The mechanism of conduction in the intermediate region is associated interlayer ionic conduction and in the highest temperature region is associated modified interlayer ionic conduction.

• Journal of Korea Multimedia Society
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• v.16 no.10
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• pp.1135-1146
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• 2013

In this paper, we proposed a new algorithm for individual tooth region segmentation on tooth color images. The proposed algorithm used oral cavity model based on structural feature of tooth and new boundary of watershed algorithm. First, the gray scale image is obtained with emphasized tooth regions from the color images and unnecessary regions are removed on tooth images. Next, the image enhancement of tooth images is implemented using the proposed oral cavity model, and the individual tooth regions are segmented by watershed algorithm on the enhanced images. Boundary and seeds necessary to watershed algorithm are applied boundary of binary image using minimum thresholding and region maximum value. In order to evaluate performance of proposed algorithm, we conduct experiment to compare conventional algorithm with proposed algorithm. As a result of experiment, we confirmed that the proposed algorithm is more improved detection ratio than conventional algorithm at molar regions and the tooth region detection performance is improved by preventing overlap detection on oral cavity.

• The Korean Journal of Ecology
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• v.17 no.1
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• pp.69-78
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• 1994

The acidic deposition (wet) was collected at three different locations; representative industrial (Kun-Jang industrial areas), semiindustrial (Kunsan City) and nonindustrial (Daeya areas) region between March, 1991 and June, 1993. Samples were analyzed for major chemical components along with pH. Also the responses of Hypnum filunzaeforme to the acidic deposition adjusted to pH 4.6, 3.6 and 2.6 with 1:4 molar ratio of nitric to sulfuric acid were investigated. Seasonal variation of pH showed the lowest in early spring and the highest in summer. The annual mean concentrations of $S0_4^{2-},\;NO_3^{-}\;and\;NH_4^{+}$ were 2.94 (81.0%), 0.48 (13.2%) and 0.21 (5.78%) mg/l in industrial region and 0.61 (64.21%), 0.25 (26.3%) and 0.9 (9.5%) mg /I in nonindustrial region, respectively. $S0_4^{2-}$ contents of industrial region was 4 times higher than those of nonindustrial region. The ratio of $S0_4^{2-}\;to\;NO_3^{-}$ was 4.75~7.35 in industrial region and 0.69-6.36 in nonindustrial region. The acidic deposition near industrial region was associated with excess ions, expecially $S0_4^{2-}$. Nitrate reductase activity(NRA) of mosses was inhibited by acidic deposition in both regions. The time required for the maximum NRA induction by 2mM $KNO_3$ was shortened in mosses collected from industrial region. Photosynthesis of H. plumaejorme began to decrease with acidic deposition by pH below 4.6, and was completely inhibited at pH 2.6 in both regions. Water potential of mosses treated with acidic deposition was almost constant during 18 days, however after withholding the supply of acidic deposition, it was rapidly decreased.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.16 no.1
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• pp.113-126
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• 1986

This study was undertaken to document and better define this condition to help clarify this clinical and radiographic appearances by the analysis of clinical and radiographic features of cementoma. A study was made of a series of 104 cases with cementoma. This investigation of cementoma revealed the following features: 1. The female occurred in 73% of periapical cemental dysplasia and benign cementoblastoma, and 80% of cementifying fibroma. 2. 40% of periapical cemental dysplasia occurred in the fifth decades, and 73% of benign cementoblastoma during the second and third decades, while there was no age predilection in the cementifying fibroma. 3. 63% of periapical cemental dysplasia occurred in the mandibular anterior region. 91% of benign cementoblastoma and 80% of cementifying fibroma occurred in the mandibular premolar and/or molar region. 4. There were no cases complaining the associated clinical signs and subjective symptoms in the periapical cemental dysplasia, however the patient complained the pain in 36% of benign cementoblastoma and 40% of cementifying fibroma. 5. There were no cases expanding the cortical plates in the periapical cemental dysplasia, however 73% of benign cementoblastoma and all of 5 cases of cementifying fibroma showed the expansion of cortical plates. 6. Several radiographic features of the periapical cemental dysplasia were shown: a. 29% of the cases had multiple lesions. b. 53% of the cases were in the mature stage. c. During the osteolytic stage, the alveolar lamina dura was lost in 89% of the cases.

• Imaging Science in Dentistry
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• v.50 no.1
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• pp.31-36
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• 2020

Purpose: The purpose of this study was to investigate the impact of radiotherapy on mandibular bone tissue in head and neck cancer patients through an analysis of pixel intensity and fractal dimension values on digital panoramic radiographs. Materials and Methods: Thirty patients with radiographic records from before and after 3-dimensional (3D) conformational radiotherapy were selected. A single examiner carried out digital analyses of pixel intensity values and fractal dimensions, with the areas of interest unilaterally located in the right angle medullary region of the mandible below the mandibular canal and posterior to the molar region. Results: Statistically significant decreases were observed in the mean pixel intensity (P=0.0368) and fractal dimension (P=0.0495) values after radiotherapy. Conclusion: The results suggest that 3D conformational radiotherapy for head and neck cancer negatively affected the trabecular microarchitecture and mandibular bone mass.

• Journal of Life Science
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• v.13 no.5
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• pp.751-755
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• 2003

Cyclic AMP receptor proteins(CRP) activate many genes in Escherichia coli by binding of cAMP with not fully known mechanism. CRP existed as apo-CRP in the absence of cAMP, $CRP;(cAMP)_2$$_2$ at low(micromolar) cAMP concentration, or $CRP;(cAMP)_4$ at high(millimolar) concentration of cAMP. This study is designed to measure the thermal stability of S83G CRP, which substituted glycine for serine at amino acid 83 position, with CD spectrapolarimeter at 222nm by the constant elevation of temperature from $20^{\circ]C\; to\; 90^{\circ}C\; at\; 1^{\circ}C/min$. The non-linear regression analysis showed that melting temperatures were 68.4, 72.0, and $82.3^{\circ}C$ for no cAMP, 0.1mM cAMP, and 5mM cAMP, respectively. Result showed the strong thermal stability of CRP by binding of additional cAMP molecules to region between the hinge region and helix-turn-helix(HTH) motif at 5mM cAMP concentration.

• The Journal of Korean Academy of Prosthodontics
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• v.31 no.2
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• pp.207-218
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• 1993

The purpose of this study was to evaluate the reproducing accuracy of stone casts made from complete arch impressions using different impression materials. The impression materials studied were 1) polyether, 2) polysulfide, 3) polyvinyl siloxane, and 4) irreversible hydrocolloid. Impressions were made from a partially edentulous acrylic resin model with metal inserts in canine, first molar region bilaterally and mid palatal vault region. Each distance between 2 out of 5 meauring points was measured by using 3dimensional measuring machine. Impressions were poured at once with a type IV dental stone. Data were analyzed using t-test with a sample size of six. The results were as follow : 1. Polysulfide and polyether were significantly superior to polyvinyl siloxane and irreversible hydrocolloid in reproducing full arch model(p<0.05), but there were no statistical differences in amount of dimensional reproducing accuracy for full arch impression between polysulfide and polyether(p>0.05). 2. There were statistical differences in amount of dimensional reproducing accuracy between edentulous area and tooth bound area for polysulfide and polyether(p<0.05). but no statistical differences were observed for polyvinyl siloxane and irreversible hydrocolloid(p>0.05).