• The korean journal of orthodontics
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• v.45 no.4
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• pp.180-189
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• 2015

Objective: To compare the positions of the mandibular premolars in Angle Class I subjects according to vertical facial type. The results will provide a theoretical basis for predicting effective tooth movement in orthodontic treatment. Methods: Cephalometric parameters were determined using cone-beam computed tomography in 120 Angle Class I subjects. Subjects were categorized as short, normal, and long face types according to the Frankfort mandibular angle. Parameters indicating the position of the mandibular right premolars and the mandible were also measured. Results: The angle between the mandibular first premolar axis and buccal cortex, the distance between the root apex and buccal cortex, angle of vestibularization, arc of vestibularization, and root apex maximum movable distance were significantly greater in the short face type than in the long and norm face types. The angle between the mandibular second premolar axis and buccal cortex, the distance from root apex to buccal cortex, and the arc of vestibularization were significantly greater in the short face type than in the normal face type. Conclusions: There are significant differences in the mandibular premolar positions in Class I subjects according to vertical facial type.

• The Journal of Korea Assosiation for Disability and Oral Health
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• v.13 no.1
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• pp.43-46
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• 2017

Patients with cerebral palsy have higher risk of traumatic dental injuries because of clinical characteristics, such as, ataxia, large overjet and lip incompetency. Especially, intrusive luxation has rare occurrence but higher incidence of complications. It can be treated by expecting re-eruption, orthodontic reposition, and surgical reposition. Clinicians should be aware of management and follow-up in dealing with cerebral palsy patients who are exposed by intrusive luxation, due to their involuntary movement. This case report describes a 9-year-old male patient with cerebral palsy and epilepsy who experienced intrusion of maxillary permanent central incisor. After one-month follow-up, waiting for spontaneous eruption, pulp necrosis on maxillary permanent central incisor had proceeded. Therefore, surgical reposition with resin wire splint and apexification was performed under conscious sedation with midazolam. After two months, removal of resin wire splint was done. Gutta percha filling and composite resin restoration were performed after sixteen months. During five-year follow-up ankylosis and partial root resorption were observed. But there was no significant complications.

• International Journal of Oral Biology
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• v.34 no.2
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• pp.53-59
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• 2009

Periodontal ligament (PDL) tissue is a connective tissue that is interposed between the roots of the teeth and the inner wall of the alveolar bone socket. PDL is always exposed to physiologic mechanical force such as masticatory force and PDL cells play important roles during orthodontic tooth movement by synthesizing and secreting different mediators involved in bone remodeling. The Wnt/${\beta}$-catenin signaling pathway was recently shown to play a significant role in the control of bone formation. In the present study, we applied cyclic tensile stress of 20% elongation to cultured human PDL cells and assessed its impact after six days upon components of the Wnt/${\beta}$-catenin signaling pathway. RTPCR analysis showed that Wnt1a, Wnt3a, Wnt10b and the Wnt receptor LRP5 were down-regulated, whereas the Wnt inhibitor DKK1 was up-regulated in response to these stress conditions. In contrast, little change was detected in the mRNA expression of Wnt5a, Wnt7b, Fz1, and LRP6. By western blotting we found decreased expression of the ${\beta}$-catenin and p-GSK-3${\beta}$ proteins. Our results thus show that mechanical stress suppresses the canonical Wnt/${\beta}$-catenin signaling pathway in PDL cells.

• Imaging Science in Dentistry
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• v.42 no.2
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• pp.83-88
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• 2012

Purpose : The aim of this study was to investigate the initial effects of maxillary expansion therapy with Hyrax appliance and to evaluate the related changes in maxillary sinus volume. Materials and Methods : Thirty patients (20 females, 10 males; 13.8 years) requiring maxillary expansion therapy, as part of their comprehensive orthodontic treatment, were examined. Each patient had cone-beam computed tomography (CBCT) images taken before (T1) and after (T2) maxillary expansion therapy with a banded Hyrax appliance. Multiplanar slices were used to measure linear dimensions and palatal vault angle. Volumetric analysis was used to measure maxillary sinus volumes. Student t tests were used to compare the pre- and post-treatment measurements. Additionally, differences between two age groups were compared with Mann-Whitney U test. The level of significance was set at p=0.05. Results : Comparison of pre-treatment to post-treatment variables revealed significant changes in the transverse dimension related to both maxillary skeletal and dental structures and palatal vault angle, resulting in a widened palatal vault (p<0.05). Hard palate showed no significant movement in the vertical and anteroposterior planes. Nasal cavity width increased on a mean value of 0.93mm(SD=0.23, p<0.05). Maxillary sinus volume remained virtually stable. No significant age differences were observed in the sample. Conclusion : Hyrax expansion therapy did not have a significant impact on maxillary sinus volume.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.33 no.2
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• pp.109-113
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• 2007

Introduction. In patients with mandibular prognathism, Bilateral Sagittal Split Ramus Osteotomy(BSSRO) combined with orthodontic treatment reduces oral volume and influences tongue and other surrounding tissues. Purpose of this study was to analyze post-operative tongue position and airway dimension, as well as mandibular changes in vertical, horizontal, and angular dimensions. Materials and methods. Height of dorsum of tongue, width of airway, gonial angle and lower facial height of mandibular prognathic patients who visited Kangdong Sacred Heart Hospital from Jan. 2001 to Dec. 2006 were anaylzed via pre-operative and post-operative cephalograms. T-test was used to compare pre-operative and post-operative measurements. Also, correlations among pre-operative measurements of the patients were analyzed. Results and conclusion. A significant correlation was shown between ANS-Xi-PM area and location of dorsum of tongue in pre-operative patients. A significant superior movement of tongue and decrease of airway width was observed in post-operative patients. Also the upper gonial angle decreased significantly.

• Journal of Dental Rehabilitation and Applied Science
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• v.30 no.4
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• pp.329-338
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• 2014

Patients who lost molars from dental caries or periodontitis have difficulty in maintaining their vertical dimension because their incisors and premolars also show vertical tooth movement. Missing posterior molars leads to occlusal interference and collapse of occlusal plane due to extrusion of opposite teeth and tipping of adjacent teeth. When this condition persists over long time, mandible moves forward, so it causes mobility and labioversion of upper incisors. This progress cannot be stopped spontaneously and the situation gets worse and worse. Therefore, for a patient with pathologic teeth migration caused by chronic periodontitis, interdisciplinary approach which is including periodontal treatment, orthodontic teeth alignment and prosthetic restoration of missing molars is required. This case report shows successful multidisciplinary approach to a patient who lost vertical dimension due to severe dental caries and periodontitis.

• The korean journal of orthodontics
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• v.36 no.6
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• pp.465-473
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• 2006

Objective: This study evaluated the effects of nitric oxide (NO) on the proliferation and differentiation of human periodontal ligament cells involved in orthodontic tooth movement. Methods: A range of concentrations of sodium nitroprusside (SNP), a NO donor, were administered to samples of human periodontal ligament cells, followed by measurement of cell viability, alkaline phosphatase (ALP) activity, and expression of osteonectin and bone sialoprotein. Results: Cell viability, ALP activity and the expression of osteonectin and bone sialoprotein were increased in human periodontal ligament cells treated with SNP concentrations of < 0.2 mM compared with controls, but were decreased with SNP concentrations of > 1.0 mM. Conclusion: NO has a biphasic effect on proliferation and differentiation in human periodontal ligament cells, with a stimulatory effect at low concentrations and an inhibitory effect at high concentrations.

• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.4
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• pp.479-484
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• 2000

The conventional treatment of skeletal class III malocclusion has been focused on the application of orthopedic forrce primarily to the mandible. Thus moderate Class III malocclusions can be corrected by the anterior displacement of the maxilla and maxillary dentition, possibly by restricting the growth of the mandible or by changing its direction. The patients having skeletal Class III malocclusion were treated with removable appliance & fixed appliance for detailed tooth movement and the following results were observed: 1. The anterior crossbite was corrected. 2. The forward and downward growth of the maxillary complex was obtained. 3. The lingual tipping of the mandiblar incisors was performed and the mandible was rotated in the clockwise direction.

• The korean journal of orthodontics
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• v.43 no.1
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• pp.42-52
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• 2013

The aim of this paper was to propose a new method of bimaxillary orthognathic surgery planning and model surgery based on the concept of 6 degrees of freedom (DOF). A 22-year-old man with Class III malocclusion was referred to our clinic with complaints of facial deformity and chewing difficulty. To correct a prognathic mandible, facial asymmetry, flat occlusal plane angle, labioversion of the maxillary central incisors, and concavity of the facial profile, bimaxillary orthognathic surgery was planned. After preoperative orthodontic treatment, surgical planning based on the concept of 6 DOF was performed on a surgical treatment objective drawing, and a Jeon's model surgery chart (JMSC) was prepared. Model surgery was performed with Jeon's orthognathic surgery simulator (JOSS) using the JMSC, and an interim wafer was fabricated. Le Fort I osteotomy, bilateral sagittal split ramus osteotomy, and malar augmentation were performed. The patient received lateral cephalometric and posteroanterior cephalometric analysis in postretention for 1 year. The follow-up results were determined to be satisfactory, and skeletal relapse did not occur after 1.5 years of surgery. When maxillary and mandibular models are considered as rigid bodies, and their state of motion is described in a quantitative manner based on 6 DOF, sharing of exact information on locational movement in 3-dimensional space is possible. The use of JMSC and JOSS will actualize accurate communication and performance of model surgery among clinicians based on objective measurements.

• The korean journal of orthodontics
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• v.47 no.3
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• pp.195-206
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• 2017

Facial asymmetry can be classified into the rolling-dominant type (R-type), translation-dominant type (T-type), yawing-dominant type (Y-type), and atypical type (A-type) based on the distorted skeletal components that cause canting, translation, and yawing of the maxilla and/or mandible. Each facial asymmetry type represents dentoalveolar compensations in three dimensions that correspond to the main skeletal discrepancies. To obtain sufficient surgical correction, it is necessary to analyze the main skeletal discrepancies contributing to the facial asymmetry and then the skeletal-dental relationships in the maxilla and mandible separately. Particularly in cases of facial asymmetry accompanied by mandibular yawing, it is not simple to establish pre-surgical goals of tooth movement since chin deviation and posterior gonial prominence can be either aggravated or compromised according to the direction of mandibular yawing. Thus, strategic dentoalveolar decompensations targeting the real basal skeletal discrepancies should be performed during presurgical orthodontic treatment to allow for sufficient skeletal correction with stability. In this report, we document targeted decompensation of two asymmetry patients focusing on more complicated yaw-dependent types than others: Y-type and A-type. This may suggest a clinical guideline on the targeted decompensation in patient with different types of facial asymmetries.