• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.38 no.2
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• pp.96-100
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• 2012

Objectives: This study sought to evaluate trabecular changes in the mandible using fractal analysis and to explain the transient osteopenia related to rapid orthodontic tooth movement after orthognathic surgery. Materials and Methods: Panoramic radiographs were taken of 26 patients who underwent bilateral sagittal split ramus osteotomy. Radiographs taken before the surgery and 1 month after surgery were overlapped, and $40{\times}40$ pixel square regions of interest were selected near the mandibular canines and 1st molars. After the image processing procedure, the fractal dimension was calculated using the box-counting method. Results: Fractal dimension after orthognathic surgery decreased in a statistically significant manner (P<0.05). The change in fractal dimension on the canine side had greater statistical significance as compared to that seen on the 1st molar side. Conclusion: This study found that bone density decreases after orthognathic surgery due to transient osteopenia related to the regional acceleratory phenomenon. This result can provide a guide to evaluating orthodontic tooth movement after orthognathic surgery.

• The korean journal of orthodontics
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• v.42 no.5
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• pp.227-234
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• 2012

Objective: To evaluate the presurgical orthodontic tooth movement of mandibular teeth after dental decompensation for skeletal Class III deformities on the basis of vertical skeletal patterns. Methods: This cohort was comprised of 62 patients who received presurgical orthodontic treatment. These patients were divided into 3 groups according to their vertical skeletal patterns. Changes in the positions of the mandibular central incisor, canine, premolar, and 1st molar after presurgical orthodontic treatment were measured using a cone-beam computed tomography (CBCT) superimposition method. Results: The incisors moved forward after dental decompensation in all 3 groups. The canines in group I and the 1st premolars in groups I and III also moved forward. The incisors and canines were extruded in groups I and II. The 1st and 2nd premolars were also extruded in all groups. Vertical changes in the 1st premolars differed significantly between the groups. We also observed lateral movement of the canines in group III and of the 1st premolar, 2nd premolar, and 1st molar in all 3 groups (p < 0.05). Conclusions: Movement of the mandibular incisors and premolars resolved the dental compensation. The skeletal facial pattern did not affect the dental decompensation, except in the case of vertical changes of the 1st premolars.

• The korean journal of orthodontics
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• v.48 no.1
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• pp.3-10
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• 2018

Objective: The purpose of this study was to predict the optimal bending angles of a running loop for bodily protraction of the mandibular first molars and to clarify the mechanics of molar tipping and rotation. Methods: A three-dimensional finite element model was developed for predicting tooth movement, and a mechanical model based on the beam theory was constructed for clarifying force systems. Results: When a running loop without bends was used, the molar tipped mesially by $9.6^{\circ}$ and rotated counterclockwise by $5.4^{\circ}$. These angles were almost similar to those predicted by the beam theory. When the amount of tip-back and toe-in angles were $11.5^{\circ}$ and $9.9^{\circ}$, respectively, bodily movement of the molar was achieved. When the bend angles were increased to $14.2^{\circ}$ and $18.7^{\circ}$, the molar tipped distally by $4.9^{\circ}$ and rotated clockwise by $1.5^{\circ}$. Conclusions: Bodily movement of a mandibular first molar was achieved during protraction by controlling the tip-back and toe-in angles with the use of a running loop. The beam theory was effective for understanding the mechanics of molar tipping and rotation, as well as for predicting the optimal bending angles.

• The korean journal of orthodontics
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• v.49 no.3
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• pp.188-193
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• 2019

Objective: The aim of this finite element study was to clarify the mechanics of tooth movement in palatal en-masse retraction of segmented maxillary anterior teeth by using anchor screws and lever arms. Methods: A three-dimensional finite element method was used to simulate overall orthodontic tooth movements. The line of action of the force was varied by changing both the lever arm height and anchor screw position. Results: When the line of action of the force passed through the center of resistance (CR), the anterior teeth showed translation. However, when the line of action was not perpendicular to the long axis of the anterior teeth, the anterior teeth moved bodily with an unexpected intrusion even though the force was transmitted horizontally. To move the anterior teeth bodily without intrusion and extrusion, a downward force passing through the CR was necessary. When the line of action of the force passed apical to the CR, the anterior teeth tipped counterclockwise during retraction, and when the line of action of the force passed coronal to the CR, the anterior teeth tipped clockwise during retraction. Conclusions: The movement pattern of the anterior teeth changed depending on the combination of lever arm height and anchor screw position. However, this pattern may be unpredictable in clinical settings because the movement direction is not always equal to the force direction.

• The korean journal of orthodontics
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• v.53 no.5
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• pp.307-316
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• 2023

Objective: To evaluate the effects of an electric toothbrush with vibrational frequencies of 125 Hz and 150 Hz on the orthodontic tooth movement (OTM) rate and the production of prostaglandin E2 (PGE2). Methods: Out of thirty patients (aged 18-25 years; 16 females and 14 males), ten patients each formed Group A and B, who used electric toothbrushes with 125 Hz and 150 Hz vibrations, respectively. The remaining ten patients (Group C) served as the control group and did not use electric toothbrushes. The rate of OTM and levels of PGE2 using microcapillary pipettes were calculated before the start of retraction (T0), on the 30th day (T1), on the 60th day (T2), and on the 90th day (T3) from the start of retraction in all the groups. Results: There was a statistically significant difference in the mean OTM values and PGE2 levels in all three groups at different time intervals, with the maximum difference seen in Group B compared to Group A and least in Group C at T1, T2 and T3. Conclusions: The rate of OTM and levels of PGE2 were highest in patients who used an electric toothbrush with 150 Hz mechanical vibration compared to those who used an electric toothbrush with 125 Hz mechanical vibration and least in patients who did not use an electric toothbrush. Mechanical vibration led to an increase in the PGE2 levels and accelerated the OTM.

• The korean journal of orthodontics
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• v.44 no.6
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• pp.320-329
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• 2014

Objective: To investigate the involvement of ephrinB2 in periodontal tissue remodeling in compression areas during orthodontic tooth movement and the effects of compressive force on EphB4 and ephrinB2 expression in osteoblasts and osteoclasts. Methods: A rat model of experimental tooth movement was established to examine the histological changes and the localization of ephrinB2 in compressed periodontal tissues during experimental tooth movement. RAW264.7 cells and ST2 cells, used as precursor cells of osteoclasts and osteoblasts, respectively, were subjected to compressive force in vitro. The gene expression of EphB4 and ephrinB2, as well as bone-associated factors including Runx2, Sp7, NFATc1, and calcitonin receptor, were examined by quantitative real-time polymerase chain reaction (PCR). Results: Histological examination of the compression areas of alveolar bone from experimental rats showed that osteoclastogenic activities were promoted while osteogenic activities were inhibited. Immunohistochemistry revealed that ephrinB2 was strongly expressed in osteoclasts in these areas. Quantitative real-time PCR showed that mRNA levels of NFATc1, calcitonin receptor, and ephrinB2 were increased significantly in compressed RAW264.7 cells, and the expression of ephrinB2, EphB4, Sp7, and Runx2 was decreased significantly in compressed ST2 cells. Conclusions: Our results indicate that compressive force can regulate EphB4 and ephrinB2 expression in osteoblasts and osteoclasts, which might contribute to alveolar bone resorption in compression areas during orthodontic tooth movement.

• Journal of the korean academy of Pediatric Dentistry
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• v.37 no.4
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• pp.537-544
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• 2010

Anchorage control in orthodontic treatment is an important factor affecting treatment results. In the conventional approach, intra-oral anchorage such as application of differential force and moment, Nance holding arch and lingual arch, as well as extra-oral anchorage such as head gear were used for anchorage reinforcement. However, these anchorages may result in undesired tooth movement and require patient cooperation. To overcome these disadvantages, skeletal anchorage system was introduced as orthodontic anchorage. Types of skeletal anchorage include implant, onplant, miniplate and miniscrew. Especially, miniscrew has many advantages such as reduced patient cooperation, low cost and easy placement. Recently, it is successfully used in orthodontic treatment. This cases were treated using orthodontic miniscrews for retraction of ectopically erupting maxillary canine and impacted mandibular canine and intrusion of maxillary incisors.

• The korean journal of orthodontics
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• v.31 no.4 s.87
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• pp.415-424
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• 2001

Anchorage in orthodontics is very important factor for orthodontist to treat malocclusion from diagnosis and treatment planning to end of treatment. Skeletal anchorage like miniscrew is supposed to be more effective method in anchorage control than conventional anchorage which needs patient's good cooperation. So this article will be mentioned about various clinical application of miniscrew through the general investigation and case reports about orthodontic use of miniscrew, specially about screwing area and clinical consideration of miniscrew's screwing on midpalate. The changes of treatment philosophy and methods by using skeletal anchorage were summarized and following results were obtained. 1. The orthodontic anchorage changed from relative concept to absolute one. 2. Bodily movement of teeth gets easier and determinate force system is possible on biomechanical consideration. 3. Some part of treatment that needs surgical intervention is possible by just orthodontic treatment.

• The korean journal of orthodontics
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• v.47 no.2
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• pp.130-141
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• 2017

The aim of this case report was to describe an innovative orthodontic treatment method that combined surgical and orthodontic techniques. The novel method was used to achieve a positive result in a case of moderate crowding by employing a computer-guided piezocision procedure followed by the use of clear aligners. A 23-year-old woman had a malocclusion with moderate crowding. Her periodontal indices, oral health-related quality of life (OHRQoL), and treatment time were evaluated. The treatment included interproximal corticotomy cuts extending through the entire thickness of the cortical layer, without a full-thickness flap reflection. This was achieved with a three-dimensionally printed surgical guide using computer-aided design and computer-aided manufacturing. Orthodontic force was applied to the teeth immediately after surgery by using clear appliances for better control of tooth movement. The total treatment time was 8 months. The periodontal indices improved after crowding correction, but the oral health impact profile showed a slight deterioration of OHRQoL during the 3 days following surgery. At the 2-year retention follow-up, the stability of treatment was excellent. The reduction in surgical time and patient discomfort, increased periodontal safety and patient acceptability, and accurate control of orthodontic movement without the risk of losing anchorage may encourage the use of this combined technique in appropriate cases.

• Journal of the korean academy of Pediatric Dentistry
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• v.32 no.3
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• pp.543-549
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• 2005

The maxillary canine is especially important as it has the longest root, provides guidance for lateral movement of the mandible and masticatory function and is a key in esthetics due to its position. Maxillary canine has the longest time to develop and a complex route from the place of formation to the site of eruption, and so it is prone to impaction more than other teeth. The clinician should consider the various treatment options : (a) No treatment and observation, (b) surgical exposure and orthodontic traction (c) autotransplantation (d) extraction. Surgical exposure of the canine and orthodontic treatment to bring the tooth into the line of occlusion is considered the most desirable approach. This case presents the results of treatment for impacted maxillary canine by surgical exposure and orthodontic tooth movement.