• The korean journal of orthodontics
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• v.37 no.6
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• pp.407-420
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• 2007

The aim of this study was to compare the differences in closing extraction spaces between maxillary first premolar and second premolar extractions using 3-dimensional finite element analysis (FEA). Methods: Maxillary artificial teeth were selected according to Wheeler's dental anatomy. The size and shape of each tooth, bracket and archwire were made from captured real images by a 3D laser scanner and FEA was performed with a 10-noded tetrahedron. A $10^{\circ}$ gable bend was placed behind the bull loop on a $0.017"{\times}0.025"$ archwire. The extraction space was then closed through 12 repeated activating processes for each 2mm of space. Results and Conclusions: The study demonstrated that the retraction of anterior teeth was less for the second premolar extraction than for the first premolar extraction. The anterior teeth showed a controlled tipping movement with slight extrusion, and the posterior teeth showed a mesial-in rotational movement. For the second premolar extraction, buccal movement of posterior teeth was highly increased.

• The korean journal of orthodontics
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• v.28 no.6 s.71
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• pp.893-904
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• 1998

There are varieties of severe malocclusions, which can be treated orthodontically, but with a great deal of effort. Anterior openbite, in particular, is one malocclusion thought to be more difficult to treat, and therefore, most of them have to be corrected by means of surgical intervention. To solve these problems, numerous studies pertinent to treatment modalities have been introduced with controversies on the effectiveness of treatment. Suggested treatment modalities for anterior openbite are based directly or indirectly on the neuromuscular and morphological features and on the etiologic and/or the environmental factors. Even though the vertical relationship of the face is increased due to the growth variation, the normal occlusal relationship can be achieved by the adequate dentoalveolar compensatory mechanism, but in the case of inadequate or negative dentoalveolar compensation, openbite is likely to be present. If the skeletal dysplasia is too severe to be solved by orthodontic treatment alone, combined treatment with surgery should be done to restore the function and the esthetics of the orofacial complex. In many cases, however, orthodontic alteration of the dentition pertinent to the given skeletal pattern with the proper diagnosis and treatment planning can bring satisfactory results. The treatment changes with the Multiloop Edgewise Archwire(MEAW) therapy occurred mainly in the dentoalveolar region and showed a considerable similarity to the natural dentoalveolar compensatory mechanism. In other words, the MEAW technique allows orthodontists to produce the natural dentoalveolar compensation orthodontically. Even if an openbite is corrected by the orthodontic dentoalveolar compensation suitable for the skeletal pattern, relapse may still occur by the persisting etiologic factors which originally prohibited the natural dentoalveolar compensation. The etiologic factors should be determined at the time of initial diagnosis and should be controlled during treatment and retention.

• Journal of Dental Rehabilitation and Applied Science
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• v.30 no.4
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• pp.265-277
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• 2014

Purpose: The purpose of this study was to investigate the differences of displacement pattern depending on type of sliding jig and application method during maxillary molar distalization with temporary anchorage devices (TADs). Materials and Methods: Maxilla with normal tooth size and arch shape was selected to create a 3-dimensional finite element model, which included the bracket, orthodontic main archwire, removable sliding jig (R-jig). The orthodontic mini-implant anchorage was set 8 mm superiorly from main archwire, buccally between the second premolar and first molar. The base experimental design was Condition 1, which was composed $0.019{\times}0.025$ inch stainless steel (SS) of wire size of R-jig, 200 gm force, un-tied state. And the other designs varied to wire size of R-jig, magnitude of force. The results are as follows. Results: As the wire size of R-jig was increased, the deformation of R-jig was decreased. However, the displacement of second molar wasn't different each other. As the force to second molar was increased, the more displacement of second molar was observed, and the more distal tipping movement, vetical displacement was observed. Conclusion: R-jig can get distal teeth movement in orthodontic treatment without side effects.

• Journal of Korean Dental Science
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• v.2 no.2
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• pp.18-23
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• 2009

Introduction : The purposes of this study were to analyze the differences between the anterior and posterior overjets using bracket slot points, and compare two methods of overjet calculation according to different reference points using clinical bracket points on three-dimensional digital models. Methods : A total of 35 normal occlusion models were scanned using a three-dimensional scanner (Orapix$^{(R)}$, Orapix Co., Ltd, Seoul, Korea) and then, virtual brackets (0.022" Slot MBT preadjusted brackets, 3 M Co.CA. USA) were placed on the digital models using virtual setup program (3Txer$^{(R)}$ ver. 1.9.6, Orapix co., Ltd). Archwire-like curves were designed to analyze labial and buccal overjet. Results : There were no statistically significance differences between the right and left overjet and between genders. The average overjet was found to be $1.67{\pm}0.85mm$ at the central incisor area, $2.16{\pm}0.88mm$ at the second premolar and $1.53{\pm}0.71mm$ at the first molar. Conclusion : It is recommended that overjet of individualized upper and lower arch to be 2.0mm at the anterior and posterior teeth.

• The korean journal of orthodontics
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• v.20 no.2
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• pp.409-417
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• 1990

Tooth movement would be impeded by frictional force arised between archwire and tube, bracket or elastics in the fixed orthodontic appliances, which could be changed variably by such several factors as the contact area, normal (perpendicular) force and the condition of contact surface. There were many literatures about frictional force in the orthodontic region, but different results were obtained from little controlled research so that was very difficult in clinical application. Therefore we have reviewed comprehensively previous literatures about frictional force and thus several results were obtained as follows: 1. For use species of the orthodontic wire, frictional force was influenced mainly by surface roughness of wire in the absence of binding, while that was influenced mainly by normal force in high binding angulation. 2. For the cross-section and diameter of the wire, the contact area influenced mainly on frictional force in the absence of binding, while wire stiffness influenced mainly on frictional force in high binding angulation. 3. The greater the bracket width, the greater frictional force, and frictional force of the plastic bracket was larger than that of the metal bracket. 4. For ligation type, frictional force of the stainless steel ligation was larger than that of the elastic ligation, and frictional force was directly proportional to ligation force. 5. Variable frictional force were occured from the saliva combined with such another factors as normal force and mode of surface oxide et al.

• The korean journal of orthodontics
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• v.22 no.1
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• pp.17-30
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• 1992

Since 1984, many patients have been treated with Multiloop Edgewise Archwire (MEAW) Technique and diagnosed with ODI (Overbite Depth Indicator) and APDI (Anteroposterior Dysplasia Indicator) by the authors. 234 samples of them were selected randomly for the statistical analysis (age, sex, Angle's classification, treatment period, extraction, ODI etc.). Especially, ODI was analysed statistically and its application methods were reviewed. The results and conclusions were as follows: 1. On the 150 patients with normal overbite, the mean values of Class I, II, III malocclusion were $67.5^{\circ}$, $72.2^{\circ}$ and $59.0^{\circ}$. They were significantly different on the level of p < 0.01. 2. In normal overbite samples, ODI decreased with the increase of APDI and the correlation coefficient was -0.54. It seems that this result reflects the characteristics of AB to mandibular plane angle. 3. The regression equation was Y = - 0.57X + 114.64, where X is APDI and Y is ODI. In cases of small or large APDI, it seems to be absurd that the patient's ODI is compared with the mean ODI to differentiate diagnostically the open bite or deep bite tendency from the normal.

• The korean journal of orthodontics
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• v.21 no.3
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• pp.685-699
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• 1991

The purpose of this report is to review vertical dysplasia such as openbite or deep bite in skeletal Class III malocclusion and their treatment modality and to present two cases treated with MEAW. The results obtained were as follows A. Open bite case 1. The treatment time was 3 year 8 months. 2. Upper and lower incisors showed extrusion and especially lower anterior alveolar process showed remodelling. 3. The mesially inclined upper and lower molars were uprighted and especially lower first molars showed extrusion that means remodelling of alveolar bone. 4. Normal overbite and overjet were established. 5. Mandible showed slight clockwise rotation. 6. Maxilla showed slight downward bending of ANS part. 7. Upper lip showed downward drop and lower lip showed retraction and touch between upper and lower lip was established. 8. Tongue posture of post-treatment was more raised than pretreatment. B. Deep bite case 1. The treatment time was 1 year 8 months. 2. Upper incisors showed intrusion and labioversion and lower incisors showed slight intrusion and linguoversion. 3. The lower molars showed distal uprighting and intrusion and upper molars showed mesial movement and extrusion. 4. Normal overbite and overjet were established. 5. Maxilla did not show downward movement. 6. Mandible showed slight clockwise rotation. 7. Lower lip showed retraction and downward drop and upper lip showed downward drop.

• The korean journal of orthodontics
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• v.36 no.6
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• pp.474-482
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• 2006

Self-ligating brackets have a permanently installed movable component to entrap the archwire which reduces much of the friction created by conventional ligation. Therefore, it allows for rapid tooth movement and shorter overall treatment time. Due to these advantages, interest in self-ligating brackets is increasing. In this report, several practical considerations for using self-ligating brackets are given to appreciate and maximize their benefits. It is thought that self-ligating brackets make shorter and more efficient treatment possible.

• The korean journal of orthodontics
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• v.51 no.6
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• pp.397-406
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• 2021

Objective: The purpose of this study was to evaluate the effects of self-ligating brackets (SBs) and other factors that influence orthodontic treatment outcomes. Methods: This two-armed cohort study included consecutively treated patients in a private practice. The patients were asked to choose between SBs and conventional brackets (CBs); if any patient did not have a preference, he or she was randomly allocated to the CB or SB group. All patients were treated using an identical archwire sequence. Evaluated parameters were as follows: treatment duration, number of bracket failures, poor oral hygiene, poor elastic wear, extraction, use of orthodontic mini-implants (OMI), OMI failure, American Board of Orthodontics (ABO) Discrepancy Index (DI), arch length discrepancy, and ABO Cast-Radiograph Evaluation (CRE) score. Stepwise regression analysis was performed to generate the equation for prediction of the CRE. Results: The final sample comprised 134 patients with an average age of 22.73 years. The average DI, CRE, and treatment duration were 21.81, 14.25, and 28.63 months, respectively. Analysis of covariance showed a significant difference in CRE between the CB and SB groups after adjusting for the effects of confounding variables. Stepwise regression analysis using four variables, namely extraction, SB use, poor elastic wear, and additional appliance use, could explain only 25.2% of the variance in the CRE. Conclusions: Although the CRE was significantly better for CBs than for SBs, the clinical significance of this result seems to be limited. Extraction, SB use, poor elastic wear, and additional appliance use may have significant effects on treatment outcomes.

• The korean journal of orthodontics
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• v.36 no.5
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• pp.339-348
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• 2006

Objective: With development of the skeletal anchorage system, orthodontic mini-implant (OMI) assisted on masse sliding retraction has become part of general orthodontic treatment. But compared to the emphasis on successful anchorage preparation, the control of anterior teeth axis has not been emphasized enough. Methods: A 3-D finite element Base model of maxillary dental arch and a Lingual tipping model with lingually inclined anterior teeth were constructed. To evaluate factors influencing the axis of anterior teeth when OMI was used as anchorage, models were simulated with 2 mm or 5 mm retraction hooks and/or by the addition of 4 mm of compensating curve (CC) on the main archwire. The stress distribution on the roots and a 25000 times enlarged axis graph were evaluated. Results: Intrusive component of retraction force directed postero-superiorly from the 2 mm height hook did not reduce the lingual tipping of anterior teeth. When hook height was increased to 5 mm, lateral incisor showed crown-labial and root-lingual torque and uncontrolled tipping of the canine was increased.4 mm of CC added to the main archwire also induced crown-labial and root-lingual torque of the lateral incisor but uncontrolled tipping of the canine was decreased. Lingual tipping model showed very similar results compared with the Base model. Conclusion: The results of this study showed that height of the hook and compensating curve on the main archwire can influence the axis of anterior teeth. These data can be used as guidelines for clinical application.