• The korean journal of orthodontics
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• v.32 no.6 s.95
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• pp.425-434
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• 2002

The purpose of this investigation was to study the spatial changes of the maxillofacial complex following maxillary protraction transmitted to the center of resistance of a dry juvenile human skull by a modified maxillary protraction appliance. Four dry juvenile human skulls (without mandible) with well aligned upper deciduous dentition and early mixed dentition were used as experimental samples. A modified protraction headgear was fabricated from a Delare's facemask, and following an alginate impression, an orthodontic resin maxillary splint was made for each dry skull. Protraction force level was maintained at approximately 1000gm per side for 6 hours. Cephalometric radiographs were taken pre- and post- protraction, and nine reference markers with 1.5 mm length of $.017\times.025$ TMA wire were placed on the right side of the skull for an accurate superimposition of serial cephalometric radiographs. The present investigation demonstrated that vertical changes associated with an anterior displacement of the maxillary complex was observed, and the most prominent effect of protraction headgear was a counterclockwise rotation of the maxilla, that is, a forward and downward tipping around the palatomaxillary region.

• Journal of the korean academy of Pediatric Dentistry
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• v.37 no.1
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• pp.117-123
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• 2010

Tooth eruption is the movement of the tooth from the developing place in the alveolar bone to the functional position in the oral cavity. The permanent incisors originate from the dental lamina on the lingual side of preceding deciduous tooth and erupt to the level of the occlusion through the well developed gubernacular cord. Ectopic eruption is a developmental disturbance in the eruption pattern of the permanent dentition. Most of the ectopically erupted lower incisor has been found in lingual side. The ectopically erupted tooth could be repositioned by orthodontic force in the early mixed dentition, which could help preventing the problems of loss of space and the lingual tilting of the lower anterior teeth. An eight-year-old girl visited the department of pediatric dentistry, Yonsei Dental University Hospital, for the evaluation and the treatment of the lower right lateral incisor, which was horizontally erupted in the lingual side, parallel to the mouth floor. Her tongue was placed on the labial side of that tooth. There was no previous dental history of dental caries or trauma on the pre-occupied primary incisor. Clinical and radiographic examinations including the computed tomography(CT), showed no evidence of dilacerations on root. Therefore, we decided to start active orthodontic traction of the lower right lateral incisor. We designed the fixed type of buccal arch wire and the lip bumper with hook for the traction. Button was attached to the lingual side of the ectopically positioned tooth. Elastic was used between the appliance and the button on that tooth. After the tooth become upright over the tongue level, appliance was change to the removable type and periodic check-up with occlusal guidance was followed to monitor the position of the tooth. In this case using the fixed appliance with modified form of lip bumper and hook embedded in acrylic part instead of extraction was very efficient up-righting the ectopically erupted tooth toward the occlusal plane.

• Journal of the korean academy of Pediatric Dentistry
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• v.38 no.3
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• pp.303-308
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• 2011

Tooth impaction refers to situations in which the eruption is inhibited by some physical barriers in eruptive path and the tooth remains unerupted beyond the normal time of eruption. The etiology of impacted tooth is controversial, but ankylosis has been suggested probably as a leading role. Impacted primary molars may cause several problems such as space loss, tipping of adjacent teeth, supra-eruption of the antagonists, dislocation of succeeding premolar, cystic change and infection. As one of conventional treatments of impacted primary molars, early tooth extraction or surgical extraction following space regaining when there is space loss has been suggested. However, when they are in normal formation and not ankylosed, orthodontic traction following surgical exposure can be the choice of treatment. In this case, a 3-year-old boy was referred to the department of pediatric dentistry for the unerupted mandibular right second primary molar. After surgical removal of gingiva on the occlusal surface, orthodontic traction was performed. After treatment, we could get normal alignment of primary teeth and the opportunity for normal development of permanent teeth.

• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.3
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• pp.481-489
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• 2007

Maxillary canine impaction is a frequently encountered clinical problem, and it may cause the resorption of adjacent tooth or cystic change. Treatment plan for maxillary canine impaction should be decided among extraction, orthodontic traction and autotransplantation according to several factors such as direction and position of unerupted tooth, degree of developing root apex, eruption space, exsitance of supernumerary tooth, odontoma, or cyst. Autotransplantation is a valuable alternative to extraction of impacted teeth, where surgical exposure and subsequent orthodontic realignment are difficult or impossible due to unfavorable impaction position. And its prognosis is dependent on a number of factors such as preservation of periodontal ligament, degree of root development, surgical technique, patient's age, endodontic treatment, time and type of splinting and storage medium, etc. The patients in these cases visited our dental clinic in the late permanent dentition with the chief complaint of unerupted maxillary canines. And it was thought that the spontaneous eruption guidance or orthodontic traction and alignment were difficult because of its unfavorable impacted position. Therefore, autotransplantaion and endodontic treatment were done and have been checked periodically until now.

• The Journal of the Acoustical Society of Korea
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• v.27 no.7
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• pp.350-356
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• 2008

In this paper, we propose shading functions to the appropriate focused beamforming for near-field target estimation. This near field shading functions are based on Chebychev and Manning windows. In order to obtain the optimum sensor weighting values with the help of the proposed shading technique, we assume that the sensor positions associated to the non-uniformly distributed array are precisely known. We calculate a series of sensor weighting values from the FFT operation of given shading functions in time domain. By applying the shading weights on the sensor array, we can see that the level of sidelobe becomes diminished and the performance of estimating range and azimuth gets improved. In addition, we propose a non-uniform structure in terms of frequency bands, which may minimize the attenuation of incoming signals.

• The korean journal of orthodontics
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• v.39 no.6
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• pp.362-371
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• 2009

Objective: The purpose of this study was to compare the longitudinal treatment effects of facemask with rapid maxillary expansion (FM/RME) and chincup (CC) therapy followed by fixed orthodontic treatment (FOT) in Class III malocclusion (CIII) patients. Methods: The samples consisted of twenty-one CIII patients who had similar skeletal and dental characteristics before FM/RME or CC therapy and good retention results (Class I molar/canine relationship and positive overbite/overjet) after FOT (Group 1, FM/RME, n = 11; Group 2, CC, n = 10). Lateral cephalograms were taken before (T0) and after FM/RME or CC therapy (T1), and after FOT and retention (T2). Skeletal and dental variables were measured. Mann-Whitney U-test and Wilcoxon signed-rank test were used for statistical analysis. Results: During T0-T1, FM/RME therapy induced forward movement of point A, and labioversion of the upper incisors. Both groups showed posterior repositioning of the mandible. FM/RME resulted in increase of the vertical dimension; however, CC caused an increase in articular angle and decrease in gonial angle. During T1-T2, both groups exhibited forward growth of point A. Group 1 showed forward growth and counterclockwise rotation of the mandible and increase of IMPA; however, Group 2, showed increase of ANS-Me/N-Me and decrease of overbite. Conclusions: The key factor for successful FM/RME and CC therapy and good retention results might be a harmonized forward growth of the maxilla that could keep pace with the growth and rotation of the mandible.

• Journal of the korean academy of Pediatric Dentistry
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• v.31 no.3
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• pp.406-411
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• 2004

Inverted Impaction of the permanent maxillary central incisor is rare. The causes of impaction are trauma and periapical inflammation of primary maxillary incisor teeth. Treatment options for a inverted incisor is extraction, surgery and orthodontic traction, transplantation, and spontaneous eruption guidance. Treatment depends on the incisor's root development and the space available for eruption. If root development is immature, prognosis would be good. We reported successful treatment for inverted maxially central incisor of proper eruption and normal root development by correction of a eruption route. But further observation will be required to evaluate the final root development state and amount of at tachment gingiva.

• The korean journal of orthodontics
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• v.38 no.5
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• pp.304-313
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• 2008

Objective: The purpose of this study was to evaluate the stress distribution in bone and displacement distribution of the miniscrew according to the length and number of the miniscrews used for the fixation of miniplate, and the direction of orthodontic force. Methods: Four types of finite element models were designed to show various lengths (6 mm, 4 mm) and number (3, 2) of 2 mm diameter miniscrew used for the fixation of six holes for a curvilinear miniplate. A traction force of 4 N was applied at $0^{\circ}$, $30^{\circ}$, $60^{\circ}$ and $90^{\circ}$ to an imaginary axis connecting the two most distal unfixed holes of the miniplate. Results: The smaller the number of the miniscrew and the shorter the length of the miniscrew, the more the maximum von Mises stress in the bone and maximum displacement of the miniscrew increased. Most von Mises stress in the bone was absorbed in the cortical portion rather than in the cancellous portion. The more the angle of the applied force to the imaginary axis increased, the more the maximum von Mises stress in the bone and maximum displacement of the miniscrew increased. The maximum von Mises stress in the bone and maximum displacement of the miniscrew were measured around the most distal screw-fixed area. Condusions: The results suggest that the miniplate system should be positioned in the rigid cortical bone with 3 miniscrews of 2 mm diameter and 6 mm length, and its imaginary axis placed as parallel as possible to the direction of orthodontic force to obtain good primary stability.

• Korean Journal of Cleft Lip And Palate
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• v.8 no.2
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• pp.63-70
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• 2005

Patients with cleft lip and palate usually show up maxillary hypoplasia. In these cases, a large amount of maxillary advancement is often needed to correct the severe deformity, but local soft-tissue scars around the maxilla restrict maxillary advancement and increase the relapse rate. Maxillary distraction osteogenesis is an effective method for facial and occlusal improvement in these patients. By gradually lengthening both the bones and the soft tissues, distracted midface can greatly increase postoperative stability and decrease the relapse rate. However, the maxillary extraoral appliances of the early days used were esthetically unappealing as well as difficult for the patient to manage. Recently, more inconspicuous intraoral distraction appliances have been developed and used with success. We acquired favorable result in two patients(bilateral 1 patient and unilateral 1 patient) with severe maxillary hypoplasia secondary to complete cleft lip and palate were treated with midface distraction using internal distractor (Zurich Pediatric Maxillary Distractor, KLS Martin, Tuttlingen, Germany). So, we report our experience with literatures.

• Journal of the Korean Orthopaedic Association
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• v.54 no.3
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• pp.211-218
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• 2019

Herniation of the intervertebral disc is a medical disease manifesting as a bulging out of the nucleus pulposus or annulus fibrosis beyond the normal position. Most lumbar disc herniation cases have a favorable natural course. On the other hand, surgical intervention is reserved for patients with severe neurological symptoms or signs, progressive neurological symptoms, cauda equina syndrome, and those who are non-responsive to conservative treatment. Numerous surgical methods have been introduced, ranging from conventional open, microscope assisted, tubular retractor assisted, and endoscopic surgery. Among them, microscopic discectomy is currently the standard method. Biportal endoscopic spinal surgery (BESS) has several merits over other surgical techniques, including separate and free handling of endoscopy and surgical instruments, wide view of the surgical field with small skin incisions, absence of the procedure of removing fog from the endoscope, and lower infection rate by continuous saline irrigation. In addition, existing arthroscopic instruments for the extremities and conventional spinal instruments can be used for this technique and surgery for recurred disc herniation is applicable because delicate surgical procedures are performed under a brightness of 2,700 to 6,700 lux and a magnification of 28 to 35 times. Therefore, due to such advantages, BESS is a novel technique for the surgical treatment of lumbar disc herniation.