• Tribology and Lubricants
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• v.30 no.4
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• pp.212-217
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• 2014

A counter gear transmits the rotation angle, so the angular velocity ratio of the gear does not necessarily need to be constant in the meshing process. As a pinion has a small number of teeth when combined with an internal gear for counters, tooth interference can occur with the use of an involute curve. This paper introduces circular arcs that represent a tooth profile and fillet for the profile design of a pinion through the combination of arcs with lines. The straight line of a rack tooth represents the profile of a mating internal gear. Thus, the circular arc and line maintain contact during the rotation of the counter gear. This paper presents an analysis of the meshing of the circular arc tooth and rack tooth along with the properties of the counter gear, such as the change in rotational velocity and amount of backlash. The contact ratio of the counter gear is 1 because the tooth contact occurs between circular arcs and line. The initial position of tooth contact, which denotes the simultaneous contact of two teeth, is found. As the rotation of the pinion, only one tooth keeps the contact situation. This meshing property is analyzed by the geometrical constraints of the tooth profile in contact and the results are presented as graphical diagrams in which tooth-arc movements are superimposed.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.6
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• pp.95-100
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• 2010

For orthodontic treatment, most commonly, an archwire is inserted into orthodontic brackets that can be made from stainless steel. Then, the archwires interact with the brackets to move teeth into the desired positions. However, the activation of an archwire may induce undesirable rotation of a tooth due to the moment application. An appropriate magnitude of the gable bends of an archwires prevents its rotation. However, it is not easy to predict the relationship between the rotation and the gable bend. This study presents the numerical approach to predict the rotation of a tooth with respect to the gable bend in the activation of an archwire. To predict the rotation of a tooth, the kriging interpolation method is introduced.

• Journal of Korean society of Dental Hygiene
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• v.11 no.4
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• pp.465-474
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• 2011

Objectives : The removal of most reliable mechanical dental plaque that is to say tooth brushing was generalized to control of dental plaque, many oral health goods have also developed due to the effect differences followed by individual habit. The electric toothbrush have studied and developed widely as major field of study that electric toothbrush having various moving phase was sold and developed at the market. Methods : Accordingly author studied about selling electric toothbrushes shape (vibration type, ultra-sonic minuteness vibration type, semi rotation type) to raise the efficiency after comparing to the moving them that total 8 groups classified by poor tooth models for example normal set of tooth, crowding tooth, bracket attached tooth, prosthetic status etc. and executed plaque removal effect on the tooth through comparing experiment. Results : The removal rate of artificial plaque on the tooth was improved in proportion to the increase of tooth brushing time(p<0.05). The ultra-sonic minuteness vibration and semi rotation type was superior to toothbrush of vibration type comparing to the removal rate of plaque on the tooth(p<0.05). Conclusions : The electric toothbrush of supersonic minuteness vibration and semi rotation type can be recommended most of tooth types regardless of oral tooth setting status for example, normal set of tooth, crowding tooth, bracket attached tooth, porcelain tooth.

• Restorative Dentistry and Endodontics
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• v.40 no.2
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• pp.166-171
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• 2015

A palato-radicular groove (PRG) is a developmental anomaly primarily found in the maxillary lateral incisors. It is a potential communication path between the root canal and the periodontium that decreases the survival prognosis of the affected tooth, therefore compromising the stability of the dental structure in the oral cavity. The aim of this case report is to present an original technique where a PRG was treated by means of intracanal disinfection, PRG sealing with glass ionomer, replantation with intentional horizontal 180 degree rotation of the tooth, and an aesthetic veneer placed to provide adequate tooth morphology. The clinical and biological benefits of this novel technique are presented and discussed.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.4
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• pp.59-65
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• 2010

This paper presents the study on the contact stress analysis of a pair of mating spur gears during rotation. Contact stress analysis is performed between two spur gear teeth at different contact positions during rotation. An example is presented to investigate the variation of contact stress on a pair of mating gears with contact positions. The variation of contact stress during rotation is compared with the contact stress at lowest point of single tooth contact(LPSTC) and AGMA Equation for contact stress. The results show that contact stress varies along the contact position and gets maximum values in the beginning and end of the contact. In this study, the gear design considering the contact stress on a pair of mating gears is more severe than that of AGMA standard.

• The Journal of the Korean dental association
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• v.54 no.7
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• pp.551-562
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• 2016

There are interferences between the teeth to be moved and the clear aligner made from setup. These interferences generate forces which move teeth to the desired position. However, these can cause incomplete tooth capture of clear aligner. When these interferences exceed the acceptable deformation of aligner, unwanted intrusion of teeth to be moved occurs. When correction of rotation or tipping of teeth is attempted, intrusion prevails before rotation or tipping. However, clear aligner can induce labiolingual tipping or intrusion easily. To achieve preliminary alignment including control of rotation and tipping, NiTi archwires with fixed appliance can be used first, and then clear aligner can be used for finishing in mild Class I maloccusion cases. For this purpose, clear aligner can be made using a digital setup and 3D printing. To move teeth using a clear aligner, tooth capture is critical. To improve tooth capture of clear aligners, slingshot or vertical elastics can be used. These were discussed with illustrations.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.6
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• pp.195-200
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• 2012

In this study, parameters and requirements of an 120kW class monorail planetary gearbox was analysed and the adaptive planetary gearbox design was selected. The specification of the sun gear, planetary gear and carrier was set and the profile & lead was optimized. The mechanical efficiency of the optimized one and the original one was observed. Dynamo-tester system was used to observe the mechanical efficiency of the planetary gearbox. A dynamo unit was connected with the planetary gearbox which straightened through the motor by a coupling. The standard tooth shape planetary gearbox and modified tooth shape planetary gearbox were used as test pieces and the rotation speed was set from 600 to 6000rpm with 600rpm, 2.5min one step. In order to check the mechanical efficiency of the planetary gearbox, the tests were done as follows. 1) The power loss between driving motor and dynamo tester. 2) Temperature variation by different rotation speeds. 3) Noise variation by different rotation speeds.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.6
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• pp.77-83
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• 2013

Orthodontics is a branch of dentistry that is concerned with the study and treatment of malocclusion, which may result from tooth irregularities, disproportionate jaw relationships, or both. Orthodontic devices consist of brackets, archwire connected to each bracket, and bends and hooks for auxiliary functions. Basically, orthodontics involves the interaction of brackets and archwire. It should be noted that uncontrolled tipping can occur due to unwanted movement of the teeth. The bending of an archwire can control the angle of an archwire and the rotation of a tooth. In this study, we predict the relationship between the bending angle of an archwire and the rotation of a tooth using the Kriging interpolation method. Also, we calculate the angle of an archwire that occurs at the minimum value of tooth rotation.

• Journal of Periodontal and Implant Science
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• v.50 no.3
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• pp.146-158
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• 2020

Purpose: The aim of this study was to investigate and identify the main causes of periodontal tissue change associated with labial gingival recession by examining the anterior region of patients who underwent orthodontic treatment. Methods: In total, 45 patients who had undergone orthodontic treatment from January 2010 to December 2015 were included. Before and after the orthodontic treatment, sectioned images from 3-dimensional digital model scanning and cone-beam computed tomography images in the same region were superimposed to measure periodontal parameters. The initial labial gingival thickness (IGT) and the initial labial alveolar bone thickness (IBT) were measured at 4 mm below the cementoenamel junction (CEJ), and the change of the labial gingival margin was defined as the change of the distance from the CEJ to the gingival margin. Additionally, the jaw, tooth position, tooth inclination, tooth rotation, and history of orthognathic surgery were investigated to determine the various factors that could have affected anterior periodontal tissue changes. Results: The mean IGT and IBT were 0.77±0.29 mm and 0.77±0.32 mm, respectively. The mean gingival recession was 0.14±0.57 mm. Tooth inclination had a significant association with gingival recession, and as tooth inclination increased labially, gingival recession increased by approximately 0.2 mm per 1°. Conclusions: In conclusion, the IGT, IBT, tooth position, tooth rotation, and history of orthognathic surgery did not affect labial gingival recession. However, tooth inclination showed a significant association with labial gingival recession of the anterior teeth after orthodontic treatment.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.2
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• pp.90-95
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• 2011

This paper presents the study on the contact stress analysis of a pair of mating helical gears for turbo blower during rotation. Turbo blowers need high speed rotation of impeller in structure and high rate gear ratio. The use of helical gear indicated that noise was an important problem when the application involves high speeds and large power transmission. An example is presented to investigate the variation of contact stress on a pair of mating gears with contact positions. The variation of contact stress during rotation is compared with the contact stress at the lowest point of single tooth contact(LPSTC) and AGMA Equation for contact stress. In this study, the gear design considering the contact stress on a pair of mating gear is more severe than that of AGMA standard.