• Title/Summary/Keyword: retraction

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Clinical accuracy of impression technique using digital superimposition of customized abutment with subgingival margin: A case report (치은연하 변연을 가지는 맞춤형 지대주에서 디지털 중첩기술을 이용한 인상채득술의 임상 적용 증례)

  • Kim, Jin-Wan;Jeong, Chang-Mo;Yun, Mi-Jung;Lee, So-Hyoun;Lee, Hyeonjong;Huh, Jung-Bo
    • The Journal of Korean Academy of Prosthodontics
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    • v.58 no.2
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    • pp.169-175
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    • 2020
  • Traditionally, gingival retraction has been performed to obtain customized abutment impressions with subgingival margins of the implant supported prosthesis. However, gingival retraction may have side effects such as gingival recession and bleed, leading to an inaccurate impression. In order to prevent these problems, in this case, the new technique has been introduced; a customized abutment which is designed for superimposition is used. Before the connection of the abutment to the implant fixture, pre-scanned shape data are stored, and then the optical impression without gingival retraction is obtained after connecting to the fixture. The suprastructure is fabricated by superimposing the two data. This technique showed the clinical efficacy of fabricating the implant supported prosthesis with subgingival margin, which satisfied the aesthetics, convenience, and clinically acceptable marginal and internal fit.

Effects of bracket slot size during en-masse retraction of the six maxillary anterior teeth using an induction-heating typodont simulation system

  • Kim, Ji-Yong;Yu, Won-Jae;Koteswaracc, Prasad N.K.;Kyung, Hee-Moon
    • The korean journal of orthodontics
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    • v.47 no.3
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    • pp.158-166
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    • 2017
  • Objective: To investigate how bracket slot size affects the direction of maxillary anterior tooth movement when en-masse retraction is performed in sliding mechanics using an induction-heating typodont simulation system. Methods: An induction-heating typodont simulation system was designed based on the Calorific Machine system. The typodont included metal anterior and resin posterior teeth embedded in a sticky wax arch. Three bracket slot groups (0.018, 0.020, and 0.022 inch [in]) were tested. A retraction force of 250 g was applied in the posterior-superior direction. Results: In the anteroposterior direction, the cusp tip of the canine in the 0.020-in slot group moved more distally than in the 0.018-in slot group. In the vertical direction, all six anterior teeth were intruded in the 0.018-in slot group and extruded in the 0.020- and 0.022-in slot groups. The lateral incisor was significantly extruded in the 0.020- and 0.022-in slot groups. Significant differences in the crown linguoversion were found between the 0.018- and 0.020-in slot groups and 0.018- and 0.022-in slot groups for the central incisor and between the 0.018- and 0.022-in slot groups and 0.020- and 0.022-in slot groups for the canine. In the 0.018-in slot group, all anterior teeth showed crown mesial angulation. Significant differences were found between the 0.018- and 0.022-in slot groups for the lateral incisor and between the 0.018- and 0.020-in slot groups and 0.018- and 0.022-in slot groups for the canine. Conclusions: Use of 0.018-in slot brackets was effective for preventing extrusion and crown linguoversion of anterior teeth in sliding mechanics.

Characteristics of shoulder pain, muscle tone and isokinetic muscle function according to the scapular position of elite boxers

  • Lee, Ju-Hong;Kim, Ho;Shin, Won-Seob
    • Physical Therapy Rehabilitation Science
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    • v.9 no.2
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    • pp.98-104
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    • 2020
  • Objective: The shoulders are a particularly an important body part for elite boxers. The purpose of this study was to investigate the characteristics of the upper trapezius (UT), infraspinatus (IS) muscle tone, pain, and isokinetic muscle function of shoulder movements such as external rotation, internal rotation, protraction, and retraction according to the scapular position of elite boxers of the Korean national team. Design: Cross-sectional study. Methods: Using the double square method, the scapular position was measured and divided into the forward scapular position group (n=8) with a measurement distance of 135 mm or more, and the normal scapular position group (n=10) with a measurement distance of less than 135 mm. Through the numeric rating scale of the subject, the pain value displayed during movement was measured. The muscle tone of the subjects' UT and IS were measured. The isokinetic muscle function of ER, IR, protraction, and retraction were measured using isokinetic exercise equipment. Results: The results of this study showed statistically significant differences when comparing muscle tone of the UT and IS, shoulder pain, isokinetic function of ER and IR, protraction, and retraction according to scapular position (p<0.05). Conclusions: The findings of this study were that shoulder muscle tone, pain, and isokinetic muscle function were affected according to the scapular position of elite boxers. In the future, this information may be a useful indicator when studying the effects of medium and long-term intervention in elite boxers who possess these characteristics.

Effect of archwire stiffness and friction on maxillary posterior segment displacement during anterior segment retraction: A three-dimensional finite element analysis

  • Park, Choon-Soo;Yu, Hyung-Seog;Cha, Jung-Yul;Mo, Sung-Seo;Lee, Kee-Joon
    • The korean journal of orthodontics
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    • v.49 no.6
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    • pp.393-403
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    • 2019
  • Objective: Sliding mechanics using orthodontic miniscrews is widely used to stabilize the anchorage during extraction space closure. However, previous studies have reported that both posterior segment displacement and anterior segment displacement are possible, depending on the mechanical properties of the archwire. The present study aimed to investigate the effect of archwire stiffness and friction change on the displacement pattern of the maxillary posterior segment during anterior segment retraction with orthodontic miniscrews in sliding mechanics. Methods: A three-dimensional finite element model was constructed. The retraction point was set at the archwire level between the lateral incisor and canine, and the orthodontic miniscrew was located at a height of 8 mm from the archwire between the second premolar and first molar. Archwire stiffness was simulated with rectangular stainless steel wires and a rigid body was used as a control. Various friction levels were set for the surface contact model. Displacement patterns for the posterior and anterior segments were compared between the conditions. Results: Both the anterior and posterior segments exhibited backward rotation, regardless of archwire stiffness or friction. Among the conditions tested in this study, the least undesirable rotation was found with low archwire stiffness and low friction. Conclusions: Posterior segment displacement may be unavoidable but reducing the stiffness and friction of the main archwire may minimize unwanted rotations during extraction space closure.

Let's Think about 'POVERTY' in the 21st Century : Using the Q methodology of Subjective Study (21세기, '빈곤'을 생각해보다: 주관성연구, Q방법론을 활용하여)

  • Lee, Doh-Hee;Kim, Gi-Woon
    • Journal of the Korea Convergence Society
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    • v.10 no.9
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    • pp.265-272
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    • 2019
  • In this study, 'poverty', which we think in our daily life, started from something. In particular, this study typified the perception of poverty by using the 'Q methodology', a subjective research method, to examine individual subjective opinions. The results of the analysis are as follows. is a "Retraction type", and poverty is a problem of 'Retention', 'Individual Effort Problem', 'Social Structure Problem', 'Low Status' and 'Laziness'. is a "Individual Problem type", and emphasizes 'Individual Effort Problem', 'Laziness', 'Incompetence', 'Starvation' and so on. is a "Basic Problem type", and emphasizes the basic element of life such as 'The Food and Shelter problem', 'Starvation', 'Laziness', and 'No Money'. is a "Resource Distribution Problem Type" that emphasizes the problem of resource allocation according to social structural problems. This study typifies the perception of poverty using subjectivity research method on 21st century and expects converging extension study to empirical studies for generalization.