• 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 korean journal of orthodontics
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• v.21 no.1 s.33
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• pp.223-238
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• 1991

This study was carried out in order to findout the amount of tooth movement, the changes arch size and the changes in arch morphology following orthodontic treatment and to provide a guideline for to predict post-treatment arch morphology. The sample group for this study consists of 15 males and 22 females, totalling in 37 persons, who received orthodontic treatment at Orthodontic Department of Dankook Univ. Dental Hospital. They are classified into Extraction Class I treatment group (E I), Non-extraction Class I treatment group (N I), and Non-extraction Class III treatment group (N III), according to their pre-treatment malocclusion state and methods of treatment. Following conclusions and averaged dental arch form for each group were obtained by cephalometric linear measurements and dental arch measurements using pre- and post-treatment lateral cephalograms and plaster study models. 1. Intercanine width were reduced in max. of both EI and NI during the period of treatment, 2. Intermolar width were reduced in max. of EI and increased in max. of NI. Therefore although there was no difference between these two groups before the treatment, intermolar width of the max, of NI was wider than that of E1 after the treatment. 3. PMV-incisor distance and PMV-canine distance were decreased in both max. and mand. of EI and that of NI, during the period of treatment. PMV-molar distance was decreased in both max. and mand. of NI and in mand. of NIII. 4. Items that showed stability during the treatment were: max. & mand. PMV-molar distance, mand. intercanine and intermolar width in EI; mand. intercanine and intermolar width in NI; mand. & max. PMV-incisor distance, PMV-canine distance, max. PMV-molar distance and max. & mand. intercanine and intermolar width in NIII. 5. The differences in averaged canine and molar variances to post-treatment dental arch form were present only in EI and in NI. There was no variance between maxilla and mandible in each group.

• The korean journal of orthodontics
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• v.30 no.3 s.80
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• pp.335-342
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• 2000

The authors observed the long term effects of chlorhexidine varnish treatment on microbial change of dental plaque in orthodontic patients with fixed appliances. The initial sample was 100 patients who were arranged to be treated with fixed orthodontic appliances. The final sample consisted of 21 patients who could be traced for 32 weeks after application of fixed orthodontic appliances. They were classified into the experimental group (12 patients) and the control group (9 patients). The experimental group was treated with chlorhexidine varnish once a week for 4 weeks before application of fixed orthodontic appliance. The control group was not treated with chlorhexidine varnish before application of fixed orthodontic appliance. The experimental group was treated once more after 20 weeks. The microbial changes of dental plaque were analysed by indirect immunofluorescence technique at pre-treatment, post-treatment 4, 8, 20, and 32 weeks. The results were as follows. 1. In the experimental group, streptococus mutans was significantly suppressed during experimental period. (p<0.01) But, in the control group, streptococcus mutans was significantly increased after placement of fixed orthodontic appliances during experiment period. (p<0.05) 2. Streptococcus sanguis, Streptococcus mitis, Actinomyces viscosus, md Actinomyces naeslundii did not show significant change between the experimental and the control group during experiment period. So, if we treat the orthodontic patients with chlorhexidine varnish before application of fixed appliances, we may suppress the major cariogenic bacteria, Streptococcus mutans, selectively for long period.

• The korean journal of orthodontics
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• v.35 no.1 s.108
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• pp.23-34
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• 2005

Collective changes caused by orthodontic tooth movement evaluated in a specific treatment modality could give suggestive information on the specific treatment strategy. The aim of this study was to investigate retrospectively the characteristics of the orthodontic tooth movement during surgical-orthodontic treatment in order to provide an effective presurgical orthodontic treatment planning for the maxillary premolar extraction modality In the skeletal Class III malocclusion patient. Pre- and post-treatment dental casts of skeletal Class III malocclusion patients with nonextraction (N=:24) and the maxillary premolar extraction (N=31) were collected. The angulation and inclination measuring gauge(Invisitech Co. Seoul, Korea) was used to evaluate the orthodontic tooth movement. The changes in the maxillary and mandibular dental arch widths were also measured from the canines to the second molars. As a result, more palatal inclination change in the maxillary dentition was found with the premolar extraction modality than with the nonextraction modality. Linear regression analysis showed that the inter-arch width coordination was mainly due to the inclination changes of maxillary posterior teeth We conclude that the indications and proper treatment planning for surgical-orthodontic treatment in skeletal Class III malocclusion with maxillary premolar extraction could depend partly on the magnitude of the transverse inter-arch coordination especially in the maxillary dentition.

• The korean journal of orthodontics
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• v.53 no.3
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• pp.205-216
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• 2023

Objective: To investigate changes in the immature teeth of Sprague-Dawley rats during orthodontic treatment and to explore the changes in the peri-radicular alveolar bone through micro-computed tomography (CT). Methods: Twenty-five 26-day-old male Sprague-Dawley rats were included. The maxillary left first molar was moved mesially under a continuous force of 30 cN, and the right first molar served as the control. After orthodontic treatment for 7, 14, 21, 28, and 42 days, the root length, tooth volume, and alveolar bone mineral density (BMD) around the mesial root were measured through micro-CT. Results: The immature teeth continued to elongate after application of orthodontic force. The root length on the force side was significantly smaller than that on the control side, whereas the differences in the volume change between both sides were not statistically significant. Alveolar bone in the coronal part of the compression and tension sides showed no difference in BMD between the experimental and control groups. The BMD of the experimental group decreased from day 14 to day 42 in the apical part of the compression side and increased from day 7 to day 42 in the apical part of the tension side. The BMD of the experimental group decreased in the root apex part on day 7. Conclusions: The root length and volume of immature teeth showed continued development under orthodontic forces. Alveolar bone resorption was observed on the compression side, and bone formation was observed on the tension side.

• The korean journal of orthodontics
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• v.45 no.3
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• pp.130-135
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• 2015

Objective: In our previous study, glass-fiber-reinforced plastics (GFRPs) made from polycarbonate and glass fibers were prepared for esthetic orthodontic wires using pultrusion. These laboratory GFRP wires are more transparent than the commercially available nickel-titanium wire; however, an investigation of the color stability of GFRP during orthodontic treatment is needed. Accordingly, in the present study, the color stability of GFRP was assessed using colorimetry. Methods: Preparation of GFRP esthetic round wires (diameter: 0.45 mm [0.018 inch]) using pultrusion was described previously. Here, to investigate how the diameter of fiber reinforcement affects color stability, GFRPs were prepared by incorporating either $13-{\mu}m$ (GFRP-13) or $7-{\mu}m$ glass (GFRP-7) fibers. The color changes of GFRPs after 24 h, and following 1, 2, and 4 weeks of coffee immersion at $37^{\circ}C$, were measured by colorimetry. We evaluated the color stability of GFRPs by two evaluating units: the color difference (${\Delta}E^*$) and National Bureau of Standards (NBS). Results: After immersion, both GFRPs showed almost no visible color change. According to the colorimetry measurements, the ${\Delta}E^*$ values of GFRP-13 and GFRP-7 were 0.73-1.16, and 0.62-1.10, respectively. In accordance with NBS units, both GFRPs showed "slight" color changes. As a result, there were no significant differences in the ${\Delta}E^*$ values or NBS units for GFRP-13 or GFRP-7. Moreover, for both GFRPs, no significant differences were observed in any of the immersion periods. Conclusions: Our findings suggest that the GFRPs will maintain high color stability during orthodontic treatment, and are an attractive prospect as esthetic orthodontic wires.

• The korean journal of orthodontics
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• v.20 no.1
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• pp.183-195
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• 1990

The purposes of present study were to identify possible relationships between post-treatment changes and post-retention changes. The patient's models were composed of 58 samples, and were classified non-extraction group (30 samples) and extraction group (28 samples). For each sample the first models were taken prior to the start of treatment, the second models just after the end of treatment, and the third models two years after. The results were as follows: 1. In the cases of non-extraction group, increases were in intermolar width of maxilla, interbicuspid width of maxilla and arch perimeter of mandible during treatment period, but decreases were in the same measurements during post-retention period. 2. In the cases of extraction group, decreases were in intermolar width of mandible, interbicuspid widths of maxilla and mandible, arch length of mandible, arch perimeters of maxilla and mandible during treatment period. 3. Significant decreases were in the irregularity index of both extraction and non-extraction group during treatment period. 4. There were significant differences of arch dimensional changes in intermolar widths of maxilla and mandible, interbicuspid widths of maxilla and mandible, arch lengths of maxilla and mandible, arch perimeters of maxilla and mandible between non-extraction and extraction group.

• The korean journal of orthodontics
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• v.34 no.1 s.102
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• pp.47-61
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• 2004

Although the purpose of orthodontic treatment is to increase the function and esthetics of the jaws along with increasing stability, there are many side effects during the treatment itself, such as root resorption and alveolar bone resorption. Such resorption of the apical root Is unpredictable, and may even proceed into the dentin layer. Once the process has begun, it is irreversible. By evaluating the effect of many oral habits, especially that of nail biting, in correlation with the root and the periodontal tissues, the appropriate biomechanics for orthodontic treatment can be taken into consideration, along with the possibility of root resorption and alveolar bone loss during orthodontic treatment, and any legal problems that might occur. Among the male and female patients of the ages $10\~15$ without skeletal deformity, 63 were chosen as the experiment group with known nail biting habits at time of examination, and within the same age group without nail biting habits as the control. After the orthodontic treatment, number of the experiment group was 31 and the control group was 22. The periapical radiographies of anterior teeth were taken and the assesment of the root length and alveolar bone level were taken before(T1) and after(T2) the orthodontic treatment. The results from this study were as follows : 1. Before the orthodontic treatment, average crown-to-root ratio of the experimental group showed noticeably high values in 4 maxillary incisors and mandibular right central incisor. 2. Before the orthodontic treatment, comparing the root length, maxillary and mandibular right central incisors and both mandibular incisors had a smaller value in the experimental group. 3. Before the orthodontic treatment, comparing and evaluating the alveolar bone loss measured from the cemento-enamel junction to the alveolar bone crest, some crestal bone of the experiment group showed greater loss than the control. 4. After the orthodontic treatment, there was shortening of the root length and loss of the crestal bone in both groups. 5. After the orthodontic treatment, the changes of C/R ratio and the shortening of root length were significantly high in the experimental group. 6. After the orthodontic treatment, the level of alveolar crestal bone showed greater loss in the experimental group.

• The korean journal of orthodontics
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• v.47 no.1
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• pp.11-20
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• 2017

Objective: This randomized controlled trial aimed to compare the stability of mandibular arch orthodontic treatment outcomes between passive self-ligating and conventional systems during 6 months of retention. Methods: Forty-seven orthodontic patients with mild to moderate crowding malocclusions not requiring extraction were recruited based on inclusion criteria. Patients (mean age $21.58{\pm}2.94years$) were randomized into two groups to receive either passive self-ligating ($Damon^{(R)}$ 3MX, n = 23) or conventional system (Gemini MBT, n = 24) orthodontic treatment. Direct measurements of the final sample comprising 20 study models per group were performed using a digital caliper at the debonding stage, and 1 month, 3 months, and 6 months after debonding. Paired t-test, independent t-test, and non-parametric test were used for statistical analysis. Results: A significant increase (p < 0.01) in incisor irregularity was observed in both self-ligating and conventional system groups. A significant reduction (p < 0.01) in second interpremolar width was observed in both groups. Mandibular arch length decreased significantly (p = 0.001) in the conventional system group but not in the self-ligating system group. A similar pattern of stability was observed for intercanine width, first interpremolar width, intermolar width, and arch depth throughout the 6-month retention period after debonding. Comparison of incisor irregularity and arch dimension changes between self-ligating system and conventional system groups during the 6 months were non-significant. Conclusions: The stability of treatment outcomes for mild to moderate crowding malocclusions was similar between the self-ligating system and conventional system during the first 6 months of retention.

• The korean journal of orthodontics
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• v.47 no.4
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• pp.256-267
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• 2017

Objective: To evaluate transverse skeletal and dental changes, including those in the buccolingual dental axis, between patients with skeletal Class III malocclusion and facial asymmetry after bilateral intraoral vertical ramus osteotomy with and without presurgical orthodontic treatment. Methods: This retrospective study included 29 patients with skeletal Class III malocclusion and facial asymmetry including menton deviation > 4 mm from the midsagittal plane. To evaluate changes in transverse skeletal and dental variables (i.e., buccolingual inclination of the upper and lower canines and first molars), the data for 16 patients who underwent conventional orthognathic surgery (CS) were compared with those for 13 patients who underwent preorthodontic orthognathic surgery (POGS), using three-dimensional computed tomography at initial examination, 1 month before surgery, and at 7 days and 1 year after surgery. Results: The 1-year postsurgical examination revealed no significant changes in the postoperative transverse dental axis in the CS group. In the POGS group, the upper first molar inclined lingually on both sides (deviated side, $-1.8^{\circ}{\pm}2.8^{\circ}$, p = 0.044; nondeviated side, $-3.7^{\circ}{\pm}3.3^{\circ}$, p = 0.001) and the lower canine inclined lingually on the nondeviated side ($4.0^{\circ}{\pm}5.4^{\circ}$, p = 0.022) during postsurgical orthodontic treatment. There were no significant differences in the skeletal and dental variables between the two groups at 1 year after surgery. Conclusions: POGS may be a clinically acceptable alternative to CS as a treatment to achieve stable transverse axes of the dentition in both arches in patients with skeletal Class III malocclusion and facial asymmetry.