• 대한치과의사협회지
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• 제44권2호통권441호
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• pp.115-122
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• 2006

Objective : The purpose of this study was to evaluate the dimensional errors between real tooth, 3D CT image and CARP model. Materials and Methods : Two maxilla and two mandible block bones with intact teeth were taken from two cadavers. Computed tomography was taken either in dry state and in wet state. After then, all teeth were extracted and the dimensions of the real teeth were measured using a digital caliper at mesio-distal and bucco-lingual width both in crown and cervical portion. 3D CT image was generated using the V-works $4.0^{TM}$ (Cybemed Inc., Seoul, Korea) software. Twelve teeth were randomly selected for CARP model fabrication. All the measurements of 3D Ct images and CARP models were made in the same manner of the real tooth group. Dimensional errors between real tooth, 3D CT image model and CARP model was calculated. Results : 1) Average of absolute error was 0.199 mm between real teeth and 3D CT image model, 0.169 mm between 3D CT image model and CARP model and 0.291 mm between real teeth and CARP model, respectively. 2) Average size of 3D CT image was smaller than real teeth by 0.149 mm and that of CARP model was smalier than 3D CT image model by 0.067mm. Conclusion : Within the scope of this study, CARP model with the 0.291 mm average of absolute eror can aid to enhance the success rate cf autogenous tooth transplantation due to the increased accuracy of recipient bone and donor tooth.

• Journal of Periodontal and Implant Science
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• 제37권2호
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• pp.287-295
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• 2007

As a general treatment modality of subgingival tooth defect in aethetic area, implant or crown and bridge therapy after extraction of affected tooth can be used. But as more conservative treatment, crown lengthening can be considered and not to lose periodontal attachment and impair aethetic appearance, surgical extrusion can be considered as a treatment of choice. In this case report, 3 cases of surgical extrusion was represented and appropriate time for initiation of endodontic treatment according to the post-surgical tooth mobility was investigated. In 8 patient who has subgingival tooth defect in aethetic area, intracrevicular incision is performed and flap was reflected with care not to injure interproximal papillae. With forcep or periotome, tooth was luxated and sutured in properely extruded position according to biologic width with or without $180^{\circ}$ rotation. 8 cases show favorable short and long term results. In some cases, surgical extrusion with $180^{\circ}$ rotation can minimized extent of extrusion and semi-rigid fixation without apical bone graft seems to secure good prognosis. In 8 cases, endodontic treatment started about 3 weeks after surgery. This time corresponds with the moment when mobility of extruded tooth became 1 degree and this results concide with other previous reports. If it is done on adequate case selection and surgical technique, surgical extrusion seems to be a good treatment modalilty to replace the implant restoration in aethetic area.

• 대한치과의사협회지
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• 제53권7호
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• pp.450-456
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• 2015

Even the adult cleft lip and palate patient who has not had timely treatment during the growth period, can be treated with orthodontic treatment without the necessity of orthognathic surgery if only the patient is treated under correct diagnosis and fitting appliances. Initially, maxillary arch form is established by constructing trifocal circles. Posterior region can be expanded and derotated laterally with pentahelix and anterior teeth are aligned with Tiggle brackets and "ㄷ"-shaped spring. Thereafter, anterior and posterior regions are consolidated. Mandibular intercanine width should be adjusted to maxillary intercanine width which was unavoidably reduced. Mandibular anterior tooth extraction will be helpful to attain proper mandibular intercanine width and better anterior dental showing.

• Journal of Oral Medicine and Pain
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• 제23권4호
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• pp.457-473
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• 1998

This study was performed to investigate the morophological and positional correlation between the upper cervical vertebra, the oral structures and the pharyngeal tissues, and the correlation of these anatomical structures with dental features, such as teeth wear area nad tooth contact status, etc. Seventy patients with temporamandibular disorders and sixty three dental students without any signs and symptoms in head and neck region were selected for this study. All they had natural dentition without any fixed and removable protheses. Teeth wear area and arch width wre measured from the upper dental cast, tooth contact status were observed by T-Scan system$^\textregistered$ and four cephaloradiograpohs were taken from four head postures, namely, natural(NHP), forward(FHP), upward(UHP), and downward head postiure(DHP). 22 cephalometric items were measured on the films and the data were processed with SAS statistical program. The result of this study were as follows : 1. In normal group, angle of cervical vertebra tangent and of between hard and soft palate were broader in female subjects than those in male subjacets, but distance from subocciput to axis, size of soft palate, and pharyngeal space width were larger in male subjects. 2. In normal group with natural head posture, the items correlated each others from the three anatomical regions were distance between first nad second vertebra in posterior part, distance from the lingual surface of lower anterior teeth to anterior surface of soft palate, and distance from the hyoid bone to third vertebra. 3. Three set of items showed significant correlation each other in the four head postures in normal group. First set was the angle between hard and soft palate and the idstance from subocciput to posterior arch of first vertebra, second set was the distance between first and second vertebra in posterior part and the teeth wear area, third set was number and force of tooth contact and length of soft palate and distance from anterior tip of hyoid bone to mandibular plane.

• 한국정밀공학회지
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• 제3권3호
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• pp.40-71
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• 1986

By developing a computer program for the systematic design of worm gears, the design formulae and tables of AGMA, JGMA, BS and DIN are analized and compared. The computer program can be used on micro-computers. According to the input data of the reduction ratio, the center distance. the driving torque and the material as design parameters, the program calculate the most efficient worm gear dimension. The variation of the design parameters and other empirical coefficients in case of resulting an inadequate design gear dimension can be easily modified throuth the way of interactive method between the user and the monitoring system of computer. A proposal of the standardization of worm gears was made in which a standard module according to the DIN 323 standard series number was applied. For the more exact and effective calculation of the stress concentration and the deformation of gear teeth, a computer program using the boundary element method is also developed. Even the strength of the special gear shape such as Niemann's "Cavex" gear can be calculated in a short CPU-time. The most effort of this study has been layed on the developing a computer program for the correction of a tooth profile and face width which is most important design factor for an exact and wide teeth contacts under loads, especially by great and wide gears. For this purpose were investigated the tooth stiffness, the mesh interferences and the kinematics and the dynamics of gear mesh. The deflection and the deformation of the gear shaft due to the loads acting on gear and shaft were aslo considered. Some examples have shown the sufficient good status of teeth contact in which the correction of the tooth profile and face width were accomplished due to the calculated results.d results.

• 대한치과교정학회지
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• 제20권2호
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• pp.283-291
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• 1990

The purpose of this study was to measure and compare tensile and shear strength for 4 types of new direct-bonding brackets and same brackets after recycling and to evaluate the change of bracket slot width after recycling. Four types of new direct-bond brackets were bonded to recently extracted human premolar teeth and the tensile and shear strength was measured by Universal Testing Machine. The brackets were recycled by chemical process and the tensile and shear test was repeated. To evaluate the change of the bracket slot width, slot width was measured by the Topcon Universal Measuring Microscope before and after recycling. Following results were obtained: 1. There was no satistically significant difference between the tensile and shear strength of recycled brackets and those of new brackets. 2. In both new and recycled brackets, the tensile and shear strength of perforated base bracket was lower than those of photoetched, foilmesh and contou-lok mesh base brackets. (P<0.01) 3. There was no statistically significant difference in bonding strengths of control group bonded only once and two times. 4. There was no statistically significant difference in the change of the bracket slow width after recycling process. 5. Of the failure, the combination type (58%) in the tensile strength and the tooth adhesive interface (65%) in the shear strength was the most common type.

• 대한치과교정학회지
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• 제21권2호
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• pp.273-285
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• 1991

Crowded group is composed of 60 subjects who visited Yonsei University for orthodontic treatment and has no history of orthodontic treatment. Noncrowded group is composed of 26 subjects who has no crowding, considered to have a normal occlusion and no history of orthodontic treatment. Currently available and approved analytic method was used. Interrelationship between tooth size and arch size, and it's correlation on tooth crowding was studied and the following results were obtained. 1. In comparison of sum of mesiodistal width, of crown size of teeth was greater in noncrowded group than that of crowded group on both arch. (p < 0.01). 2. In comparison of arch lengths, the values measured from arch length 2 showed greater in noncrowded group (p < 0.01). Also in crowded group, arch length 1 showed greater value than arch length 2 on both arch (p < 0.01). 3. In comparison of arch widths, upper interlateral (p < 0.01) and upper intercanine width (p < 0.05) showed greater value in noncrowded group on upper arch and intermolar width showed greater value in noncrowded group on both upper and lower arches (p < 0.05). 4. In comparison of arch perimeters, arch perimeter 2 was greater value in noncrowded group on both upper and lower arches (p < 0.01). 5. Dentoalveolar disproportion was greater in noncrowded group on both upper and lower arches (p < 0.01). 6. In lower incisors MD/FL ratio, the central and lateral incisors were greater in crowded group, but statistial significance was only in lateral incisors (p < 0.01) 7. The irregularity index of lower incisors showed greater value in crowded group (p < 0.01).

• Journal of Periodontal and Implant Science
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• 제33권3호
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• pp.533-542
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• 2003

The purpose of this study is to evaluate histologic result of bone substituting material on defects followed tooth extraction. We compare the histologic findings control, DFDBA, Bio-Oss(R), and $Regenafil^{TM}$, Briefly, mandibular premolar teeth were extracted available for bone filling. All alveolar sites were checked after extraction and thoroughly debrided with a dental curet to remove the periodontal ligament. Extraction sites were prepared dehiscence on buccal side 7mm height from alveolar crest. The graft materials were filled into the extraction socket and dehiscenc defects. The animals were sacrificed 12 weeks after implantation. Both treated and control mandibular sites were histologically evaluated with light microscopy. Histologic observation at 12 weeks revealed that control and experimental sites were healed uneventfully and directly apposed to new bone without any adverse tissue reaction. DFDBA and Bio-Ossn(R)sites maintain width of alveolar crest but were not fully resorbed. $Regenafil^{TM}$ sites also maintain width and particles were resorbed more than other graft materials. From this results, it was suggested that $Regenafil^{TM}$ is promising boen substituting materials maintaining the width of alveolar crest and height follewed tooth extraction.

• 대한치과보철학회지
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• 제31권4호
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• pp.533-541
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• 1993

This study was designed to help to be given esthetics in construction of denture and prosthodontic rehabilitation of anterior tooth region. The author took the facial straight photograph of 100 old aged people(male 50, female 50) above 55 years of age, who have natural teeth in anterior tooth region, in a resting and a smiling position. And the author measured and analyzed the lip shape, the relation between the lip and the teeth and the change of lip length and height when they were smiling. The results of this study were as follows : 1. In the shape of the upper lip, when the upper lip curved downward, it was 53%, straight was 28% and curved upward was 9%. 2. In the relation between the upper lip and the teeth, average smile was 53% , high smile was 26% and low smile was 21%. 3. In the parallel relation between the lower lip and maxillary anterior incisal curvature, the group of straight was 54%, the group of parallel was 40% and the group of reverse was 6%. 4. In the relationship between maxillary anterior incisor and lower lip, the group of not-touching was 92%, the group of touching was 5% and the group of the maxillary anterior incisor were slightly covered by the lower lip was 3%. 5. In the teeth displayed in a smile, displayed to second premolar was 50%, displayed to first molar was 34%, displayed to first premolar was 12%, and displayed to canine and second molar were 2%. 6. At smiling, the width of the mouth was 0.94 times of the interpupillary distance and 0.45 times of the full face width. 7. At smiling, the length of the upper lip was 0.73 times and lower lip was 0.98 times of the length in a resting postion and the width of the mouth corner was 1.19 times of the resting position.

• Imaging Science in Dentistry
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• 제34권2호
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• pp.63-67
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• 2004

Purpose: To make a focal trough (image layer) for an average maxillary dental arch of 6-year-old korean in panoramic radiography. Materials and Methods : Phantom for the maxillary dental arch was designed using intercanine width, intermolar width, tooth size, and interdental spacing to record the data of 6-year-old child. The characteristics of pre-corrected panoramic machine (for adult) was evaluated using the phantom, resolution test pattern for margin of the image layer, and metal ball for the center of the image layer. Panoramic image layer of the child was developed by means of decreasing the speed of film-cassette and positioning the phantom backwards, and then the characteristics of post-corrected panoramic machine (for child) were reevaluated. Results: At post-corrected panoramic image layer, beam projection angles at all interdental areas increased for about 2.6-3.8°, the position of the image layer was shifted toward the rotation center for about 2.5 mm at the deciduous central incisior area. The width of image layer decreased at all areas. Conclusion : Increased beam projection angle will reduce the disadvantage of tooth overlap, and the same form between the center of the image layer and dental arch will improve image resolution.