• Journal of the Korean Academy of Esthetic Dentistry
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• v.7 no.1
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• pp.64-70
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• 1998

Recently as the interest on Esthetic Dental Prosthesis is arising, the domains of Esthetic Dentistry is being widely investigated. Esthetic Dental Prosthesis is influenced greatly by the shape, color, tooth arrangement of the teeth and the facial features(including the lips). So the degree to which these characters harmonize will be the professional esthetical standard while the satisfaction of the patient will be another esthetical measure. The reason for this is that each and every one of us has a different standard of what is considered beautiful. Of course it doesn't mean that every standard is correct. Then what does Esthetical Prosthesis mean and what should the standard be? This must be defined as a prosthesis that satisfies the basic requirements - margin, contour, occlusion, and at the same time it should restore the shape, color, and tooth arrangement which the client(patient) would love to have. As Esthetic Prosthesis contains its subjective meaning a great deal, it shouldn't be simply distinguished between the beauty of the teeth itself or ugliness. Also in some case, it needs surgical treatment to make it harmonious in the whole aspect so that one may keep the feeling of satisfaction and security. Then what is the shape, color, tooth arrangement that each individual wants? There is an indefinite variety. For example, considering arrangement both regular and irregular is considered beautiful by each different individual. Regular arrangement may be the standard of beauty for some, while irregular arrangement may be thought of as natural looking and beautiful. That is why there must be enough communication with the patient and an agreement be made at the clinic before a diagnostic plan and actual surgery. The treatment plan as mentioned above must be sent to the dental laboratory. In this research, by using case studies, I am going to the importance and appropriateness of the data and information for the dental technician's esthetic prosthesis.

• Journal of Biosystems Engineering
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• v.12 no.3
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• pp.42-49
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• 1987

The threshing action of the head-fed type threshing unit occurs mainly by the impact between threshing tooth and grains. It may be therefore the most fundamental step to calculate the time and order of the occurrance of impact by the tooth for predicting the performance of threshing unit. The threshing teeth arrangement was defined by length and diameter of threshing dram, number of spiral arrays, number of threshing teeth by kind per one spiral array, number of windings of spiral array around the threshing drum, delay angle of impact line. The linear equations for locus of left and right margin of paddy bundle, spiral array, impact line on the development figure of the threshing drum were expressed by fastors of the threshing teeth arrangement. In the computer program, the teeth which inflict impact were searched successively along the impact line. Searching range and impact condition were defined by the relation between four linear equations. If the impacting tooth was found, time and the kind of threshing tooth was derived from the coordinate of the threshing tooth. At this time the unit torque curve was accumulated on the array of computer memory. At last the completed torque curve of threshing drum shaft was described on the computer screen. Remarkably the peack valae and fluctuation of torque curve was decreased by adopting the delay angle of impact line.

• Journal of Biosystems Engineering
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• v.17 no.2
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• pp.171-176
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• 1992

This study was intended to develop the design theory of the threshing unit of a head-feeding rice combine. It may be applied for various combining capacities with different cutting widths and forward speeds. Design factors in the theoretical development are : (1) dimensions of the threshing drum, (2) tooth approching angle, (3) distance between the adjacent teeth on their spiral setting line, (4) number of spirals, and (5) total number of teeth on the drum. A computer simulation program was developed to predict the proper dimensions for the threshing drum and tooth arrangement. A simulation for the prospective combine with varied capacities was also demonstrated. The parameters analyzed in the developed design theory were shown to be consistent with those of existing combines.

• The Journal of the Korean dental association
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• v.19 no.11 s.150
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• pp.917-921
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• 1981

• Proceedings of The Korean Society of Health Promotion Conference
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• 2009.10a
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• pp.269-269
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• 2009

• Imaging Science in Dentistry
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• v.35 no.1
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• pp.25-31
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• 2005

Purpose : To evaluate the stability of the segmental occlusal plane and anatomical line as the reference line for measuring the mesiodistal tooth angulation in panoramic radiography and to determine the mean angle and the range of the mesiodistal tooth angulation in Korean population with normal occlusions. Materials and Methods : Twenty nine subjects (15 men, 14 women) with normal occlusion were selected. A total of 29 panoramic radiograms were taken at normal head position and then 10 images of 5 subjects selected were repeatedly taken with repositioning 2 times at each of the head down (V-shaped occlusion) and up (horizontal occlusion) for evaluation of stability of adopted reference lines by using PM2002CC (Planmeca, Finland). The images were traced with adoption of two test reference lines and the long axes of the teeth. The mesial angles formed by each reference line and the long axes of the teeth were measured and analyzed. Results : With anatomical reference line, the mesiodistal tooth angulations of the molars showed the significant difference by over 5 degree between the normal and each changed head position. With segmented occlusal reference line, deviations of mesiodistal tooth angulations by the two changed head positions were less than 1 degree. The means, standard deviations, and maximum and minimum values of mesiodistal tooth angulations to segmental occlusal reference line on panoramic radiography were determined. Conclusion : It would appear that mesiodistal tooth angulations to segmental occlusal plane as reference line in panograms are predictable as standards of normal occlusion and useful for evaluation of tooth arrangement between adjacent teeth.

• Restorative Dentistry and Endodontics
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• v.25 no.2
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• pp.170-179
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• 2000

The rh-BMP-4 is a subgroup of TGF-${\beta}$ superfamily. The application of rh-BMP in alveolar bony defect was reported to new alveolar bone and new cementum formation. For minimized complications following tooth replantation, a operator must replant a tooth fast at the pertinent position. This study was to evaluate the effect of rh-BMP-4 on periodontal regeneration and root resorption following tooth replantation in rats. The 50 Sprague-Dawley rats weighting about 130gm were used in this study. The animals were divided into three groups. Group 1 ; immediate replantation after extraction : Group 2 ; replantation stored teeth extraction of first molar, the removal of periodontal ligament with collagenase, and etching with citric acid : Group 3 ; replantation stored teeth with treated rh-BMP-4 in mesial root. Experimental animals were sacrificed 3, 7, 14 days after replantation by heart infusion. The maxillae were removed, fixed, demineralized, dehydrated, infiltrated and embedded with JB-4 mixture. For light microscopic observation, 5 micron sections were cut and stained with toluidine blue. The results of this study were as follows : 1. After experimental 3 days, all groups were observed dead space between periodontum and root. 2. After experimental 7 days, group 1 and group 3 were observed filling periodontal fibers between alveolar bone and root but group 2 were not. 3. After experimental 7 days, group 3 were observed appearance of attached cementoblast like cell on root surface. Group 1 were observed regular arrangement of fibroblasts and collagen fibers at ${\times}400$ observation. 4. After experimental 14 days, all group were observed filling periodontal fibers between alveolar bone and root. Group 1 were observed normal arrangement of periodontal fibers. Group 3 were observed less abnormal arrangement of periodontal fibers. Group 2 were not observed functional normal arrangement of periodontal fibers. 5. After experimental 14 days, group 2 and 3 were observed several root resorption and irregular root surface but group 1 were not. These results suggest that the rh-BMP-4 can stimulate cementogenesis and enhance to attach collagen fibers.

• Journal of the korean academy of Pediatric Dentistry
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• v.24 no.4
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• pp.758-762
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• 1997

There are various types of localized tooth malpositions in the mixed dentition, such as abnormal tooth axis, anterior crossbite of some incisors, impaction, midline diastema, ectopic eruption, and so forth. We, Pediatric Dentists, have usually used removable appliances for these instances. But, removable orthodontic appliances, as is known, have marked limitations in some situations, for example, severe rotation, intrusion and extrusion, root torque, closure of large diastema, traction of impacted tooth, etc. In such cases, Whip spring, combined with fixed or removable appliance, can increase utilities of removable orthodontic appliances. The authors have applied whip springs to some cases showing localized positional and arrangement problems, and have witnessed the results as follows; 1. The refined and elaborate control of direction and magnitude of force by the operator, and accurate compliance of the patients were requisite for the treatment with it. 2. It showed special effectiveness for de rotation of incisors. Although it yields some benefit for root movement, the special consideration for incomplete roots in this age bracket was required. 3. In the localized malalignment cases in mixed dentition, uncurable with traditional removable appliances but practically unrealistic with fixed appliance therapy, the whip spring was thought to be a good alternative.

• Journal of Korean Dental Science
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• v.14 no.2
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• pp.90-100
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• 2021

Purpose: The aim of this study was to evaluate the degree of achievement of anterior tooth movement using a thermoplastic clear aligner by superimposing pretreatment, setup, and post-treatment models and to analyze the factors that influence it. Materials and Methods: Forty patients who underwent clear aligner treatment at the Department of Orthodontics were included in the study. The pretreatment, setup, and post-treatment models were superimposed, and the achievement rates were evaluated. We analyzed the factors that caused changes in achievement rate on each condition. Result: The average achievement rate of total tooth movement was 57.65%. Mesiodistal and anteroposterior displacements were achieved better than vertical displacement and rotation. In each displacement, posterior, mesial, and extrusive movements were better achieved than the rotation. Spacing was better corrected than crowding, especially in the mesiodistal direction. Most of the tooth movements were achieved better when using 3-step thicknesses of aligners were used. Conclusion: The treatment results of clear aligners may differ depending on the type of tooth movement, age and other treatment conditions. Clinicians should consider unfavorable conditions based on the results of this study.

• The korean journal of orthodontics
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• v.50 no.6
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• pp.391-400
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• 2020

Objective: Increased gingival elasticity has been implicated as the cause of relapse following orthodontic rotational tooth movement and approaches to reduce relapse are limited. This study aimed to investigate the effects of sulforaphane (SFN), an inhibitor of osteoclastogenesis, on gene expression in gingival fibroblasts and relapse after rotational tooth movement in beagle dogs. Methods: The lower lateral incisors of five beagle dogs were rotated. SFN or dimethylsulfoxide (DMSO) were injected into the supra-alveolar gingiva of the experimental and control group, respectively, and the effect of SFN on relapse tendency was evaluated. Changes in mRNA expression of extracellular matrix components associated with gingival elasticity in beagles were investigated by real-time polymerase chain reaction. Morphology and arrangement of collagen fibers were observed on Masson's trichrome staining of buccal gingival tissues of experimental and control teeth. Results: SFN reduced the amount and percentage of relapse of orthodontic rotation. It also decreased the gene expression of lysyl oxidase and increased the gene expression of matrix metalloproteinase (MMP) 1 and MMP 12, compared with DMSO control subjects. Histologically, collagen fiber bundles were arranged irregularly and were not well connected in the SFN-treated group, whereas the fibers extended in parallel and perpendicular directions toward the gingiva and alveolar bone in a more regular and well-ordered arrangement in the DMSO-treated group. Conclusions: Our findings demonstrated that SFN treatment may be a promising pharmacologic approach to prevent orthodontic rotational relapse caused by increased gingival elasticity of rotated teeth in beagle dogs.