• The korean journal of orthodontics
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• v.30 no.4 s.81
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• pp.467-473
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• 2000

As a rectangular wire Is inserted into edgewise brackets the wire exerts a force system three-dimensionally. The force system may include bending force in first and second orders and a torsional force in third order Analytical and experimental studies on bending force have been Introduced, but information about torsion is still lack. The purpose of this study was to estimate the torsional moment in the force system of rectangular arch wires through theoretical and experimental studies. Wires most frequently used for third order control were selected as study materials. Cross sections of 0.016x0.022, 0.017x0.025, 0.019x0.025 inch rectangular wires in foot different materials such as stainless steel(Ormco), TMA(Ormco), NiTi(Ormco), and braided stainless steel (DentaFlex, Dentaurum) were used. The torque/twist rate of each test material was calculated using the torsion formula. Torque/twist rate, yield torsional moment, and ultimate torsional moment were measured with a torque gauge. The torsion formula assesses that the torque/twist rate (T/$\theta$) is proportional to the characteristics of material (G) and cross section (J), and is inversely proportional to the length of wire (L). Most experimental results corresponded with the formula. The relative stiffness was calculated for reference to a logical sequence of wire changes.

• The korean journal of orthodontics
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• v.34 no.5 s.106
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• pp.380-393
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• 2004

The Purpose of this study was to investigate the dentoalveolar compensation according to anteroposterior skeletal discrepancy in normal occlusion and to evaluate cephalometric parameters that quantitatively describe dental compensations. The study consisted of 90 subjects (50 males. 40 females) who were selected among specimens of normal occlusion at Seoul National, University Dental Hospital, Dept. of Orthodontics. Lateral cephalograms in centric occlusion were traced and digitized for each subject. According to the anteroposterior skeletal pattern the sample was divided into three groups. Cephalometric data were analyzed for the three groups using the SPSS program. Independent t-test, correlation analysis and regression analysis were carried out. The results were as fellows: Dentoalveolar compensation was found in upper and lower incisor inclination and occlusal plane inclination. As the mandible located anterior to the maxilla, the maxillary incisors incisors more labially. the mandibular incisors more lingually, and the occlusal plane continued to flatten. The dental parameters most correlated with anteroposterior skeletal discrepancy were L1 to SN and L1 to FH. Among the compensatory dentoalveolar changes, lower incisor inclination was strongly related to the anteroposterior jaw relationship and played au imposrtant role in obtaining a normal incisor relationship U1 to PtGn and L1 to APog were constant irrelevant to anteroposterior skeletal discrepancy.

• The korean journal of orthodontics
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• v.41 no.5
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• pp.354-360
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• 2011

Objective: To investigate the effects of different pilot-drilling methods on the biomechanical stability of self-tapping mini-implant systems at the time of placement in and removal from artificial bone blocks. Methods: Two types of artificial bone blocks (2-mm and 4-mm, 102-pounds per cubic foot [102-PCF] polyurethane foam layered over 100-mm, 40-PCF polyurethane foam) were custom-fabricated. Eight mini-implants were placed using the conventional motor-driven pilot-drilling method and another 8 mini-implants were placed using a novel manual pilot-drilling method (using a manual drill) within each of the 2-mm and 4-mm layered blocks. The maximum torque values at insertion and removal of the mini-implants were measured, and the total energy was calculated. The data were statistically analyzed using linear regression analysis. Results: The maximum insertion torque was similar regardless of block thickness or pilot-drilling method. Regardless of the pilot-drilling method, the maximum removal torque for the 4-mm block was statistically higher than that for the 2-mm block. For a given block, the total energy at both insertion and removal of the mini-implant for the manual pilot-drilling method were statistically higher than those for the motor-driven pilot-drilling method. Further, the total energies at removal for the 2-mm block was higher than that for the 4-mm block, but the energies at insertion were not influenced by the type of bone blocks. Conclusions: During the insertion and removal of mini-implants in artificial bone blocks, the effect of the manual pilot-drilling method on energy usage was similar to that of the conventional, motor-driven pilot-drilling method.

• The korean journal of orthodontics
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• v.41 no.5
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• pp.337-345
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• 2011

Objective: The purpose of this study was to evaluate the effect of force and moment produced by Nickel-titanium wires of different sizes at activation and deactivation according to differing vertical bracket displacement. Methods: Superelastic NiTi wires of 3 different sizes (0.014", 0.016", and 0.016" ${\times}$ 0.022") were tied with elastomeric or 0.009-inch stainless steel ligations in a twin-bracket, 0.018-inch slot. A testing machine recorded the effects of simulated activation of 5 distances from 1 to 5 mm and deactivation of 5 distances from 4 to 0 mm, in increments of 1 mm. Results: Frictional force increased the wire stiffness during loading. Ligation of 0.014-inch NiTi wire with O-ring resulted in a significant increase in the stiffness. On application of orthodontic force for 5 mm of vertical displacement of teeth, the effective displacement in the case of the 0.014", 0.016", and 0.016" ${\times}$ 0.022" NiTi wires was 2 mm, 3 mm, and 4 mm, respectively. Conclusions: Our results showed that movement of teeth with large vertical displacement was ineffective because of excessive friction. This finding might contribute to the understanding of the force system required for effective teeth movement and thereby facilitate the application of the appropriate light wire for leveling and alignment.

• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.4
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• pp.547-552
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• 2001

Extracting mandibular incisors for orthodontic treatment may adversely affect the occlusion. However, when properly used, extraction of mandibular inciors is a selection for the correction of the malocclusion. Generally, treatment for crowding needs to select between nonextraction and four premolar extraction. Approaches for crowded mandibular incisors include distal movement of posterior teeth, lateral movement of canines, labial movement of incisors, interproximal enamel reduction, removal of premolars, removal of one or two incisors, and various combinations of the above. Extraction of incisors is used in case of crowding, anterior tooth size discrepancy, absent of maxillary lateral incisors, and ectopic eruption. But severe overjet. overbite, and space are the contraindication of it. A patient had severe crowding on upper anterior teeth, impacted upper left lateral incisor, palatal ectopic eruption of upper right incisor and severe crowding on lower anterior teeth. Lower lateral incisors are extracted for space availability and facial esthetics. We report the case of orthodontic treatment of upper and lower anterior crowding through extraction of lateral incisor.

• Journal of the korean academy of Pediatric Dentistry
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• v.32 no.3
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• pp.550-556
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• 2005

Tooth impaction is defined as a cessation of the eruption of a tooth at the level of the oral mucosa or alveolar bone by any causes. Any tooth in the dental arch can be impacted, but the teeth frequently involved in a descending order are the mandibular and maxillary third molars, the maxillary canines, the mandibular and maxillary second premolars, and the maxillary central incisors. In these teeth, impaction of maxillary incisor occurs in about 0.1-0.5% and major causes are trauma, supernumerary teeth and periapical inflammation of primary maxillary incisor. Delayed eruption of a maxillary central incisor results in midline shift, the space's being occupied by an adjacent tooth and different levels of alveolar height. Treatment options are observation, surgical intervention, surgical exposure and orthodontic traction, transplantation and extraction. These cases were about the patients with delayed eruption of maxillary central incisor. We surgically exposed impacted tooth and guided it into normal position by the orthodontic traction. At the completion of traction, the maxillary central incisor was positoned fairly within the arch and complications such as root resorption were not observed.

• Journal of the korean academy of Pediatric Dentistry
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• v.40 no.2
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• pp.106-117
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• 2013

Normal eruption of the canine is important for the transition to the permanent dentition. Etiologies, including premature loss or delayed retention of deciduous teeth, neoplasm and abnormality of lateral incisor can cause impaction of the maxillary canine. Untreated canine impaction can result in malocclusion, cyst formation and obstacles in orthodontic treatment. The aim of this study is to evaluate location of the impacted maxillary canine and to identify correlation between location and management of the impaction including complications. Using panoramic radiographs and CBCT scan, images of 89 children diagnosed with impaction of the maxillary canine, location of impacted canines was evaluated. The choice of treatment and complications were investigated to identify correlation. Results show that the most commonly impacted location of the maxillary canine was in the mid-alveolar area, followed by buccal side and palatal side. Orthodontic traction was selected more frequently than the other treatments. As complications, displacement of adjacent tooth was occurred most frequently. Buccally impacted canines showed increased tendency towards displacement. The more buccally the canine was impacted, the less orthodontic traction was chosen as the treatment. The canine impacted mesially to the central incisor showed increased tendency to occur root resorption. Therefore, early diagnosis by periodic examination, appropriate treatment and intervention is required.

• Korean Journal of Social Welfare
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• v.69 no.3
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• pp.121-140
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• 2017

The purpose of this study was to use the Korea Health Panel to determine how the mother's characteristic and household characteristic variables were associated with dental clinic use of children in childhood and adolescence. The logistic regression analysis found that mother's education level was statistically significantly positively correlated with underage child's dental clinic use and children in single-parent family were less likely to use a dental clinic than those in two-parent family. As for dental clinic use by diseases, the higher level of mother's education, the more likely to use a dental clinic due to dental caries and children in single-parent family were less likely to use a dental clinic due to dental caries than those in two-parent family. No difference in dental clinic use due to tooth extraction was found by any of mother's characteristics or household characteristics, probably because age has an absolute impact during the period between milk teeth and permanent teeth. Lastly, mother's education level and household income were significantly positively correlated with dental clinic use due to orthodontics. On the basis of these results, it is necessary to develop a customized strategy reflecting children's growth stages and household characteristics in making a plan for promoting oral health of children and adolescents.

• Journal of the korean academy of Pediatric Dentistry
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• v.37 no.4
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• pp.545-550
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• 2010

Freeman-Sheldon Syndrome (FSS, also known as "Whistling Face Syndrome") is a rare genetic condition which characteristically includes a small "whistling" mouth, a flat mask-like face, club feet, joint contractures usually involving the fingers and hands, and under-development of the cartilage of the nose. Intelligence is usually normal. Most of the features of this syndrome are due to muscle weakness. The patient, 11 years old boy was consulted from pediatrics to pediatric dentistry due to dental management. After clinical & radiographic examinations, severe multiple problems were found. Dental problems were microsomia(whistling mouth) & micrognathia, perioral muscle contracture, restricted mouth opening, poor oral hygiene & care, generalized dental caries, high palatal vault, severe malocclusion & crowding. And Orthopedic problems, ophthalmic & respiratory, anesthetic problems were found. Then He also had psychiatric problem, hospital(dental) phobia due to previous medical history(frequent hospitalization). And he had genital problem, cryptochidism, too. Due to these intricate problems, he suffered with feeding, swallowing difficulties and showed growth retardation. For enhancing patient's oral health, pediatric dentist, orthodontist, oral surgeon, pediatrician, psychiatrist, orthopedist, they all agree with early, cautious intervention and treatment. So, he has been treated by multidisciplinary care, now he is recovering general health maintenance.

• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.1
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• pp.8-11
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• 2001

Langerhans Cell Histiocytosis (LCH) is characterized by proliferation of Langerhans cells. The clinical manifestation varies from solitary bone lesion to multi-system, life threatening disorder. The younger the patient is and the more system is involved, the worse the prognosis is. The jaw is involved $10\sim20$ percent of all LCH and it is involved usually in early stage of LCH. In this case the patient is three years old girl who suffered from pain of whole mandibular body and histological examination confirmed the diagnosis LCH. She is referred to pediatrics and managed with combined chemotherapy. Due to the possibility of recurrence, we follow up the girl and she need orthodontic and prosthodontic treatment in the future because of the loss of lower left 2nd premolar. We report this case because early recognized LCH in dental hospital result in good prognosis.