• The korean journal of orthodontics
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• v.42 no.6
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• pp.297-306
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• 2012

Objective: This in vitro study was undertaken to evaluate the physical, chemical, and biological properties of commercially available metal orthodontic brackets in South Korea, because national standards for these products are lacking. Methods: Four bracket brands were tested for dimensional accuracy, (manufacturing errors in angulation and torque), cytotoxicity, composition, elution, and corrosion: Archist (Daeseung Medical), Victory (3M Unitek), Kosaka (Tomy), and Confidence (Shinye Odontology Materials). Results: The tested rackets showed no significant differences in manufacturing errors in angulation, but Confidence brackets showed a significant difference in manufacturing errors in torque. None of the brackets were cytotoxic to mouse fibroblasts. The metal ion components did not show a regular increasing or decreasing trend of elution over time, but the volume of the total eluted metal ions increased: Archist brackets had the maximal Cr elution and Confidence brackets appeared to have the largest volume of total eluted metal ions because of excessive Ni elution. Confidence brackets showed the lowest corrosion resistance during potentiodynamic polarization. Conclusions: The results of this study could potentially be applied in establishing national standards for metal orthodontic brackets and in evaluating commercially available products.

• Imaging Science in Dentistry
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• v.52 no.3
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• pp.295-302
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• 2022

Purpose: Lateral cephalograms of orthodontic patients may contain incidental findings that could potentially lead to harm. Materials and Methods: The lateral cephalograms of 1765 consecutive 12- to 20-year-old patients, being considered for routine orthodontic treatment, were retrospectively reviewed. These patients were considered normal, because no abnormalities were found either in their medical history or on their clinical examination. Results: The overall prevalence of incidental findings was 18.8%, of which 10.3% were ponticulus posticus and 4.2% were bridging of the sella turcica. Although occipital spurs and ponticulus posticus were more prevalent in males, the size of the sella turcicas did not differ between sexes. Of the 1156 patients completing treatment about 2 years later, only one lateral cephalogram displayed progression of the ponticulus posticus in that time. Conclusion: The prevalence of incidental findings on lateral cephalograms of otherwise normal orthodontic 12- to 20-year-old patients was almost a fifth, of which ponticulus posticus, vertebral fusion, and enlarged parietal foramina were clinically significant.

• The korean journal of orthodontics
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• v.51 no.4
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• pp.270-281
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• 2021

Objective: The aim of this in vitro study was to evaluate the changes in friction between orthodontic brackets and archwires coated with aluminum oxide (Al₂O₃), titanium nitride (TiN), or chromium nitride (CrN). In addition, the resistance of the coatings to intraoral conditions was evaluated. Methods: Stainless steel canine brackets, 0.016-inch round nickel-titanium archwires, and 0.019 × 0.025-inch stainless steel archwires were coated with Al₂O₃, TiN, and CrN using radio frequency magnetron sputtering. The coated materials were examined using scanning electron microscopy, an X-ray diffractometer, atomic force microscopy, and surface profilometry. In addition, the samples were subjected to thermal cycling and in vitro brushing tests, and the effects of the simulated intraoral conditions on the coating structure were evaluated. Results: Coating of the metal bracket as well as nickel-titanium archwire with Al₂O₃ reduced the coefficients of friction (CoFs) for the bracket-archwire combination (p < 0.01). When the bracket and stainless steel archwire were coated with Al₂O₃ and TiN, the CoFs were significantly lower (0.207 and 0.372, respectively) than that recorded when this bracket-archwire combination was left uncoated (0.552; p < 0.01). The friction, thermal, and brushing tests did not deteriorate the overall quality of the Al₂O₃ coatings; however, some small areas of peeling were evident for the TiN coatings, whereas comparatively larger areas of peeling were observed for the CrN coatings. Conclusions: Our findings suggest that the CoFs for metal bracket-archwire combinations used in orthodontic treatment can be decreased by coating with Al₂O₃ and TiN thin films.

• The korean journal of orthodontics
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• v.52 no.6
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• pp.412-419
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• 2022

Objective: This study evaluated the effect of cyclic pre-calcification treatment on the improvement of bioactivity and osseointegration of Ti-6Al-4V mini-screws. Methods: The experimental groups were: an untreated group (UT), an anodized and heat-treated group (AH), and an anodized treatment followed by cyclic pre-calcification treatment group (ASPH). A bioactive material with calcium phosphate was coated on the mini-screws, and its effects on bioactivity and osseointegration were evaluated in in vitro and in vivo tests of following implantation in the rat tibia. Results: As a result of immersing the ASPH group in simulated body fluid for 2 days, protrusions appearing in the initial stage of hydroxyapatite precipitation were observed. On the 3rd day, the protrusions became denser, other protrusions overlapped and grew on it, and the calcium and phosphorus concentrations increased. The removal torque values increased significantly in the following order: UT group (2.08 ± 0.67 N·cm), AH group (4.10 ± 0.72 N·cm), and ASPH group (6.58 ± 0.66 N·cm) with the ASPH group showing the highest value (p < 0.05). In the ASPH group, new bone was observed that was connected to the threads, and it was confirmed that a bony bridge connected to the adjacent bone was formed. Conclusions: In conclusion, it was found that the surface treatment method used in the ASPH group improved the bioactivity and osseointegration of Ti-6Al-4V orthodontic mini-screws.

• Restorative Dentistry and Endodontics
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• v.42 no.4
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• pp.253-263
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• 2017

Objectives: The aim of the study was to evaluate the 5-year clinical performance of occlusal carious restorations using nanofill and microhybrid composites, in combination with 3-step etch-and-rinse adhesives, in patients who were going to commence orthodontic treatment. Materials and Methods: A total of 118 restorations for occlusal caries were conducted prior to orthodontic treatment. Occlusal restorations were performed both with Filtek Supreme XT (3M ESPE) and Filtek Z250 (3M ESPE) before beginning orthodontic treatment with fixed orthodontic bands. Restorations were clinically evaluated at baseline and at 1, 2, 3, 4, and 5-year recalls. Results: None of the microhybrid (Filtek Z250) and nanofill (Filtek Supreme XT) composite restorations was clinically unacceptable with respect to color match, marginal discoloration, wear or loss of anatomical form, recurrent caries, marginal adaptation, or surface texture. A 100% success rate was recorded for both composite materials. There were no statistically significant differences in any of the clinical evaluation criteria between Filtek Z250 and Filtek Supreme XT restorations for each evaluation period. Conclusions: The composite restorations showed promising clinical results relating to color matching, marginal discoloration, wear or loss of anatomical form, recurrent caries, marginal adaptation, and surface texture at the end of the 5-year evaluation period.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.40 no.4
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• pp.160-168
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• 2014

Objectives: The purpose of this study was to evaluate the condylar position in relation to the glenoid fossa before and after orthodontic-orthognathic surgical treatment and to investigate the relationship with skeletal relapse. Materials and Methods: Lateral cephalograms and temporomandibular joint tomograms from 19 patients with mandibular prognathism who received orthodontic-orthognathic surgery were included in this study. Samples were divided into two groups based on skeletal change during the retention period. The relapse group consisted of 7 patients (3 females and 4 males; mean age, 21.9 years) whose pogonion or menton displaced more than 1 mm during the retention period and the stable group consisted of 12 patients (5 females and 7 males; mean age, 21.7 years). Anterior joint space, posterior joint space, superior joint space, and anteroposterior index were measured on tomograms at pretreatment and posttreatment timepoints. Condyle position and frequency of the positional change were compared between both groups. Results: In the relapse group and stable group, 42.9% and 45.8% of the condyles, respectively, showed forward or backward displacement at posttreatment. However, the changes were small and the mean anterior, posterior, superior joint spaces and frequencies of the positional changes did not differ statistically between both groups. Conclusion: Our results suggest that small positional changes of the condyle, which may occur after orthodontic-orthognathic surgery treatment, may not be related to skeletal relapse after removal of the orthodontic appliances.

• The Journal of the Korean dental association
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• v.54 no.6
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• pp.404-413
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• 2016

Currently, dental implants have become predictable and reliable adjuncts for oral rehabilitation. Osseointegrated implants can be used to provide rigid orthodontic anchorage and have advantages compared conventional orthodontic anchorage especially when there were edentulous areas and implants were scheduled as a treatment plan. Orthodontic force doesn't cause the bone loss of osseointegrated implants. Implant materials, surgical protocols and healing time before loading follow the conventional treatment protocol. Because the implants, once installed, can't change the location, meticulous treatment planning should be preceded. Further investigations are needed to standardize the treatment protocol.

• Imaging Science in Dentistry
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• v.46 no.1
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• pp.17-24
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• 2016

Purposes: This study employed a posteriori registration and subtraction of radiographic images to quantify the apical root resorption in maxillary permanent central incisors after orthodontic treatment, and assessed whether the external apical root resorption (EARR) was related to a range of parameters involved in the treatment. Materials and Methods: A sample of 79 patients (mean age, $13.5{\pm}2.2years$) with no history of trauma or endodontic treatment of the maxillary permanent central incisors was selected. Periapical radiographs taken before and after orthodontic treatment were digitized and imported to the Regeemy software. Based on an analysis of the post-treatment radiographs, the length of the incisors was measured using Image J software. The mean EARR was described in pixels and relative root resorption (%). The patient's age and gender, tooth extraction, use of elastics, and treatment duration were evaluated to identify possible correlations with EARR. Results: The mean EARR observed was $15.44{\pm}12.1pixels$ (5.1% resorption). No differences in the mean EARR were observed according to patient characteristics (gender, age) or treatment parameters (use of elastics, treatment duration). The only parameter that influenced the mean EARR of a patient was the need for tooth extraction. Conclusion: A posteriori registration and subtraction of periapical radiographs was a suitable method to quantify EARR after orthodontic treatment, and the need for tooth extraction increased the extent of root resorption after orthodontic treatment.

• The korean journal of orthodontics
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• v.22 no.1
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• pp.147-158
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• 1992

This study was aimed to compare the relative cytotoxicity of the five common orthodontic bonding materials (Concise. Mon-lok, Ortho-One, Super C, Transbond) using cell culture technique. DNA synthesis of the fibroblasts was assessed by $^3H$-thymidine uptake to evaluate the effect of the bonding materials on the growth of the cells. The human gingival fibroblasts were explanted from the buccal gingiva of 10 year-old girl and cultured in $\alpha$-MEM/10% FBS/1% antibiotics medium, $37^{\circ}C$, 5% $CO_2$ incuvator. The gingival fibroblasts were tested with the medium into which the bonding materials had been soaked for 1 week. Or the bonding materials were placed on the cells immediately or 2 weeks after polymerization. After 22 hours, $^3H$-thymidine was added into the microtest wells and after 24 hours, the uptake of $^3H$-thymidine was determined by liquid scintilation counter. The results of this study were as follows. 1. DNA synthesis was significantly decreased with Super C and Transbond than Ortho-One, when treated with medium into which the bonding materials had been soaked for 1 week. 2. DNA synthesis was significantly decreased with Concise, Super C and Transbond than control, when treated immediately after polymerization. 3. DNA syntehsis was significantly decreased with Concise, Super C and Transbond than Ortho-One, when immediately after polymerization. 4. There was no significant difference in DNA synthesis between the bonding materials, when treated 2 weeks after polymerization.

• Journal of Korean Dental Science
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• v.4 no.1
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• pp.20-25
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• 2011

Purpose: To describe the newly developed Film image transfer system (FITS) for proper positioning of the orthodontic mini-implant in the narrow interdental space and considerations for better application. Materials and Methods: A patient who was planning to have orthodontic mini-implant treatment on the posterior maxilla was recruited to assess the feasibility of FITS. Dental radiographic film and bite record was taken. And then the film image was transferred on the photographic emulsion coated model using transfer light through film projector (enlarger). After exposing the photo emulsion coating on the model, the image was developed with a working solution for a paper developer and fixed. The surgical guide for the mini-implant was fabricated from the transported FITS data. Results: The completed surgical guide was easily placed intraorally, and allowed a simple and rapid placement of the mini-implant. The site of the implant placement was accurate as planned position. Conclusion: In the reported case, The FITS technique represents an effort to minimize risk to the patient and produce consistently good results based upon accurate information about the anatomy of the implant site.