• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.2
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• pp.268-277
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• 2008

Authors evaluated 1171 patients at the department of Pediatric Dentistry in Kyoungpook National University Hospital through clinical records and radiographs. And the following features were studied ; age, sex distribution, number of mesiodens per patients, cause of discovery of mesiodens, location, status of eruption, shape and orientation of crown, complication, dental age of adjacent upper incisor tooth at the time of surgical extraction of mesiodens and the relationship between the resolution rate of complication after extraction of mesiodens and the dental age of adjacent upper incisor tooth, length of diastema, the eruption status of lateral incisor and the crowding status of premaxilla. The followings are the results : 1. The cause of discovery of mesiodens were as follows ; delayed eruption of the permanent incisors in 13.8%, midline diastema in 11.6%, radiographs taken for other reasons in 23.4% and for caries treatment in 15.1%. 2. Complication due to the presence of mesiodens did not occur in 36.8%, delayed eruption of adjacent teeth was observed in 16.1%, midline diastema in 34.4%, rotation in 8.8%, displacement in 2.4%, and crowding in 1.0% of all evaluated patients. 3. As for the dental age of adjacent upper incisor tooth at the time of surgical extraction of mesiodens, below 1/3 of total root length were observed in 3.5%, $1/3{\sim}1/2$ of total root length in 19.9%, $1/2{\sim}2/3$ of total root length in 54.7% and over 2/3 in 21.9% of all evaluated patients. 4. Resolution rate of delayed eruption after the extraction of mesiodens was significant higher in the group with the root length below 1/2. Resolution rate of midline diastema was significant higher in the group with diastema width below 3mm and with non-crowding of adjacent upper incisor teeth.

• The korean journal of orthodontics
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• v.41 no.5
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• pp.324-336
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• 2011

Objective: The aim of this study was to conduct three-dimensional finite element analysis of individual tooth displacement and stress distribution when a posterior retraction force of 200 g was applied at different positions of the retraction hook on the transpalatal arch (TPA) of a molar, and over different lengths of the lever arm on the maxillary anterior teeth in lingual orthodontics. Methods: A three-dimensional finite element model, including the entire upper dentition, periodontal ligaments, and alveolar bones, was constructed on the basis of a sample (Nissan Dental Product, Kyoto, Japan) survey of Asian adults. Individual movement of the incisal edge and root apex was estimated along the x-, y-, and z-coordinates to analyze tooth displacement and von Mises stress distribution. Results: When the length of the lever arm was 15 mm and 20 mm, the incisal edge and root apex of the anterior teeth was displaced lingually, with a maximum lingual displacement at the lever arm length of 20 mm. When the posterior retraction hook was on the root apex, the molars showed distal displacement. When the length of the lever arm was 20 mm, anterior extrusion was reduced and the crown of the canine displaced toward the buccal side, in which case, the retraction hook was on the edge, rather than at the center, of the TPA. Conclusions: The results of the analysis showed that when 6 anterior teeth were retracted posteriorly, lateral displacement of the canine and lingual displacement of the incisal edge and root apex of the anterior teeth occur without the extrusion of the anterior segment when the length of the lever arm is longer, and the posterior retraction hook is in the midpalatal area.

• Journal of Biomedical Engineering Research
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• v.41 no.2
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• pp.84-93
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• 2020

Despite of a lot of studies about proprioception tests, there are little study results to investigate the relationship between the functional movement and proprioception level. In this study, we tried to perform quantitative analysis for the effect of ankle joint proprioception level on the one leg standing postural control ability. Nine healthy people volunteered for this study. Force and position aspects of proprioception were evaluated using the electromyography system (EMG) and mobile clinometer application, respectively. The center of pressure (COP) trajectories, measured by a pressure mat sensor, were used for quantitative analysis of balance for each subject. We computed indices and errors of force and position aspects of proprioception from the EMG and ankle angle. Mean velocity of total and anterior-posterior direction (Vm and Vm_ap), root mean squared distance in anterior-posterior direction (RDap), travel length (L), and area (A) of COP trajectories were also calculated as indices of postural control ability of subjects. Two aspects of proprioception showed the low correlation from each other as previous studies. However, the EMG error of gastrocnemius lateral activation showed a high correlation coefficient with COP variables such as Vm (ρ=0.817, p=0.007), Vm_ap (ρ=0.883, p=0.002), RDap (ρ=0.854, p=0.003), L (ρ=0.817, 0.007) and A (ρ=0.700, p=0.036). Within our knowledge, this is almost the first study that investigated the relationship between proprioception level and functional movement. These study results could support that the ankle joint proprioception facilitation exercise would have positive effects on functional balance rehabilitation interventions.

• Journal of the korean academy of Pediatric Dentistry
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• v.26 no.1
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• pp.38-43
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• 1999

Tooth transposition is the phenomenon in which two teeth in the dental arch are exchanged. The tooth most frequently involved in transposition is the permanent maxillary canine, especially with the first premolar. The etiology of transposition is still an enigma. Interchange of tooth germs, migration during eruption, genetic factor, local pathologic factors may be suggested as possible etiologic factors. There are three main options for treatment, which are the extraction of one of the transposed teeth, the alignment in the transposed position, the orthodontic movement of the teeth to their correct positions. If complete transposition occurred especially in mandible, alignment of teeth in the transposed position followed by occlusal reduction and esthetic restoration is usually recommended. The presented two-case report will describe the maxillary canine to the first premolar and to lateral incisor transposition with associated peg lateralis and retained primary canines. Although alignment the transposed teeth in original position is ideal treatment, it companies many complication as root resorption, alveolar bone destruction, gingival deheisence, etc. Therefore the treatment procedures in these case was relative cost-benefit effective method to both clinician and patients.

• Journal of the korean academy of Pediatric Dentistry
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• v.42 no.1
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• pp.87-101
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• 2015

The premature loss of the mandibular primary canine is relatively frequent and a sign of the upcoming space problems in the transitional period. This situation is caused by the permanent lateral incisor resorbing the root of the primary canine during its eruption. Bilateral loss of primary canines in a crowded arch leads to the lingual tipping of the permanent incisors, with the consequent reduction in the arch perimeter and increase in overbite. When the loss of a primary canine is unilateral, tipping of the adjacent incisors occurs toward the space, resulting in midline deviation. In these situations, treatment possibilities, such as extraction of the antimeric tooth or placement of a passive lingual arch, can be applied; although there are some controversies concerning this. Most space problems with less than 4 mm can be resolved through preservation of the leeway space using sequential disking of the primary teeth and a passive lingual arch, regaining space or limited arch expansion in the late mixed dentition. In cases with 4~6 mm of space problems, arch expansion (A-P or transverse) can be applied. Space problems with more than 6 mm should be treated through diagnosis and treatment planning. Most of these cases will require extraction of permanent teeth including serial extraction (guidance of eruption).

• Archives of Plastic Surgery
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• v.35 no.3
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• pp.273-278
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• 2008

Purpose: The most widely accepted protocol for alveolar cleft reconstruction is to repair it during the mixed dentition stage. There were lower resorption rate (about 88%) at this stage. However we found some cases that need repeated bone grafting. Therefore we sought to analyze the cause of repeated alveolar bone grafting in connection with other factors. Methods: From January 2000 to January 2006, thirty-nine secondary alveolar bone grafts with iliac crest spongiosa were carried out. In 39 patients, 5 patients who had significant bone graft resorption received repeated alveolar bone graft. In all the cases, the causes of repeated bone grafts were dental root exposure(angulation), and the deficiency of the bony support for lateral incisor or canine eruption. In 3 cases, there was deficiency of the alveolar bone at the cleft side. There was the need of repeated bone grafts for orthodontic treatment in 2 cases and for application of dental implants in 1 case. Results: During the follow-up period, the clinical and radiologic examinations showed that repeated alveolar bone grafts were maintained successfully without any complications. The volume of the repeated bone graft was sufficient for orthodontic treatment and implantation. Conclusion: The essential conditions for successful alveolar bone grafting includes the status of cleft sided teeth, further treatment and planed schedule, as well as canine eruption. Alveolar bone grafting has to be performed with difference of each case in mind.

• The Journal of Korean Physical Therapy
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• v.28 no.5
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• pp.308-313
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• 2016

Purpose: This study investigated the effects of sex hormones across menstrual cycle phases on knee muscle activity during one-leg landing in non-athletic females. Methods: Twenty-six healthy females who reported normal menstrual cycles for the previous three months were tested when estrogen levels were highest (ovulation) and lowest (menstruation). Knee muscle activity was analyzed based on electromyography (EMG) data recorded during landing on a 30-cm box. Before data collection, each subject was trained in single-leg landing tasks ten times. Landing was analyzed by measuring the average of three landing tasks. EMG data were collected between the moment of ground contact and the point of knee maximum flexion. The maximum voluntary isometric contraction (MVIC) for normalization that was recorded as the EMG root-mean-square (RMS) during landing was tested, with paired t-tests used to assess differences in knee muscle activity according to menstrual cycle phases. Results: The results showed that the soleus, semitendinosus, and lateral gastrocnemius muscle activity during landing was differed significantly during ovulation compared to that during menstruation (p<0.05). No significant differences in vastus medialis activity were found between menstrual and ovulatory phases during landing (p>0.05). Conclusion: Changes in the menstrual cycle in response to sex hormones changed the activity of muscles around the knee during landing. Females utilize different muscle activity control strategies during different phases of the menstrual cycle, which may contribute to increased ACL injury risk.

• Journal of Korean Neurosurgical Society
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• v.48 no.2
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• pp.139-144
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• 2010

Objective : We report our surgical experience in the treatment of 16 consecutive patients with benign craniovertebral junction (CVJ) tumor, observed from 2003 to 2008 at our department. Methods : We had treated 6 foramen magnum meningiomas, 6 cervicomedullary hemangioblastomas, 1 accessory nerve schwannoma, 1 hypoglossal nerve schwannoma, 1 C2 root schwannoma, and 1 cavernous hemangioma. Clinical results were evaluated by Karnofsky Performance Scale (KPS) and all patients underwent preoperative neuroradiological evaluation with computed tomography (CT) and magnetic resonance image (MRI). Angiography was performed in 15 patients and preoperative embolization was done in 2 patients. Results : Five far-lateral, 1 supracondylar and 10 midline suboccipital approaches were performed. Gross total removal was achieved in 15 cases (94%) and subtotal removal in 1 patient (6%). None of the patients required occipitocervical fusion. Radiological follow-up showed no recurrence in cases totally removed. Postoperative decrease of KPS scores was recorded in only 1 patient. The treatment of cervicomedullary solid hemangioblastoma presented particular issues : by preoperative embolization, we removed tumor totally without an excessive bleeding or brainstem injury. In one of foramen magnum meningioma, we carried out subtotal removal due to hard tumor consistency and encasement of neurovascular structures. Conclusion : The choice of surgical approaches and the extent of bone resection should be defined according to the location and size of individual tumors. Moreover, we emphasize that preoperative neuroradiological evaluations on presumptive tumor type could be helpful to the surgeon in tailoring the technique and providing the required exposure for different lesions, without unnecessary surgical steps.

• Archives of Craniofacial Surgery
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• v.11 no.1
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• pp.65-68
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• 2010

Purpose: Dermoid cysts are benign neoplasms that are derived from both ectoderm and mesoderm. Approximately 7 percent of all dermoid cysts occur in the head and neck, as most common sites are the lateral ends of the eyebrows, the midline in the nasal root and neck. Rarely they can be found in the frontal sinus, temporal bone, maxilla and the floor of the mouth. Dermoid cysts in the temporal fossa are extremely rare. We experienced a characteristic dermoid cyst that occupied the temporal fossa. Methods: A 16-year-old man had a progressive enlarging mass on the left eyebrow. Computerized tomographic scan showed a bulging mass in the temporal fossa, and it had the density similar to that of fat. The size of the mass was $3{\times}3{\times}2cm$, and it was composed of high density of fat with clear margin. There was no bony invasion, but the mass was fixed on bone. Results: We performed the surgery through coronal incision under general anesthesia. Because the mass was closely connected with temporal fat pads, we removed this mass with some portion of temporal fat pads, avoiding damage to the facial nerve. The postoperative course was ordinary without complication. Conclusion: The reports about dermoid cyst on the temporal fossa is uncommon. However, if there is a mass in the temporal fossa which has the density similar to that of fat in CT scan, we should consider the possibility of dermoid cyst. We suggest that excision through coronal incision with bewaring temporal fat pad can induce good result.

• Advances in biomechanics and applications
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• v.1 no.3
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• pp.169-185
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• 2014

Computational multibody models of the elbow can provide a versatile tool to study joint mechanics, cartilage loading, ligament function and the effects of joint trauma and orthopaedic repair. An efficiently developed computational model can assist surgeons and other investigators in the design and evaluation of treatments for elbow injuries, and contribute to improvements in patient care. The purpose of this study was to develop an anatomically correct elbow joint model and validate the model against experimental data. The elbow model was constrained by multiple bundles of non-linear ligaments, three-dimensional deformable contacts between articulating geometries, and applied external loads. The developed anatomical computational models of the joint can then be incorporated into neuro-musculoskeletal models within a multibody framework. In the approach presented here, volume images of two cadaver elbows were generated by computed tomography (CT) and one elbow by magnetic resonance imaging (MRI) to construct the three-dimensional bone geometries for the model. The ligaments and triceps tendon were represented with non-linear spring-damper elements as a function of stiffness, ligament length and ligament zero-load length. Articular cartilage was represented as uniform thickness solids that allowed prediction of compliant contact forces. As a final step, the subject specific model was validated by comparing predicted kinematics and triceps tendon forces to experimentally obtained data of the identically loaded cadaver elbow. The maximum root mean square (RMS) error between the predicted and measured kinematics during the complete testing cycle was 4.9 mm medial-lateral translational of the radius relative to the humerus (for Specimen 2 in this study) and 5.30 internal-external rotation of the radius relative to the humerus (for Specimen 3 in this study). The maximum RMS error for triceps tendon force was 7.6 N (for Specimen 3).