• The korean journal of orthodontics
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• v.4 no.1
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• pp.21-29
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• 1974

The purpose of the present study is to evaluate changes of the soft tissue relative to underlying skeletal elements during orthodontic treatment, and the influence of orthodontic treatment quantitatively on various regions of the facial profile. 59 Korean young women were selected, whose Hellman dental age was IV A, IV C and V A. Lateral cephalometric head films were taken before and after orthodontic treatment. From tracings, landmarks on skeletal and soft tissue profile were located, and then their linear and angular measurements were made directly. The results were obtained as follow: 1) Soft tissues of the facial profile were closely related and dependent on the underlying dentoskeletal frameworks. Orthodontic treament resulted in the reduction of dentofacial protrusion with both upper and lower lips becoming less procumbent during treament. 2) Thickness of the upper lip increased considerably during orthodontic treatment, and this change was related to maxillary incisor retraction. The ratio between the amount of maxillary incisor retraction and that of increment of upper lip thickness was approximately 5:3. 3) Soft tissue thickness overlying Downs' point A, point B and pogonion was not modified by orthodontic treatment. 4) Holdaway's H line, relating facial profile to the underlying dentoskeletal framework, seemed to be the most practical approach to soft tissue analysis.

• The korean journal of orthodontics
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• v.24 no.3 s.46
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• pp.631-648
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• 1994

The purpose of this study was to investigate the effects of different types of orthodontic force on the root resorption and repair in rat molar. 77 rats were divided into three groups; The control group was not equiped with orthodontic appliance between incisor and first molar. The experimental group was subdivided into closed coil spring subgroup and elastic chain subgroup by the application methods of orthodontic force. Initial orthodontic force between incisor and first molar was 100g. Experimental period was 8 weeks; for 4 weeks the appliance was acting and for another 4 weeks, removed. Root resorption and repair in the root of first molar was examined by light microscope for histologic changes and by inductively coupled plasma spectroscopy(ICP) for quantitative changes. The results were as follows: 1. In the closed coil spring subgroup odontoclasts and root resolution were appeared one week earlier. 2. One week after orthodontic force was eliminated the repair response in the resorptive lacuna was seen in both subgroups. Delayed resorption was seen on the periphery of resorptive lacunae whereas reparative response was seen in the center of lacunae. A new resorption was seen one week after orthodontic force was eliminated. Root contour was partially restored by repairing of resorbed root. 3. The weight ratios of calcium and phosphorous to the sample were decreased during resorptive process but increased during repair process in both the orthodontic groups, but not more than the control group. 4. By different types of orthodontic force (closed coil spring or elastic chain) resorption process was affected but repair process was not.

• 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.

• Imaging Science in Dentistry
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• v.51 no.2
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• pp.155-165
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• 2021

Purpose: This study aimed to evaluate changes of the alveolar bone and interdental bone septum of the mandibular incisors through cone-beam computed tomography (CBCT) after orthodontic treatment of mandibular dental crowding without dental extraction. Materials and Methods: The sample consisted of 64 CBCT images(32 pre-treatment and 32 post-treatment) from 32 adult patients with class I malocclusion and an average age of 23.0±3.9 years. The width and height of the alveolar bone and interdental septum, the distance between the cementoenamel junction (CEJ) and the facial and lingual bone crests, and the inclination of the mandibular incisors were measured. Results: The distance between the CEJ and the marginal bone crest on the facial side increased significantly (P<0.05). An increased distance between the CEJ and the bone crest on the facial and lingual sides showed a correlation with the irregularity index (P<0.05); however, no significant association was observed with increasing mandibular incisor inclination (P>0.05). The change in the distance between the CEJ and the marginal bone crest on the facial side was correlated significantly with bone septum height(P<0.05). Conclusion: Bone dehiscence developed during the treatment of crowding without extraction only on the incisors' facial side. Increasing proclination of the mandibular incisor was not correlated with bone dehiscence. The degree of dental crowding assessed through the irregularity index was associated with the risk of developing bone dehiscence. The interdental septum reflected facial marginal bone loss in the mandibular incisors.

• The korean journal of orthodontics
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• v.26 no.4
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• pp.441-447
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• 1996

This study was carried out in order to find out the pattern of the root resorption following maxillary incisor retraction after maxillary 1st bicuspid extration in maxillary protrusion patients. For this study, thirty two patient who received orthodontic treatment were chosen. The results were as follows; 1. Of the total 192 teeth, 61 teeth(31.77%) showed no apical root loss, 64 teeth(33.33%) fell into the class "slight", 46 teeth(23.96%) fell into the class "moderate". Only 21 teeth(10.94%) were classified as "excessive". 2. No correlation was noted between the amount of apical root loss and the types of tooth movement of the maxillary central incisors. 3. The patients who were treated with standard brackets had more changes in tooth axis and less movement of root apexes, but the patients with straight brackets had less changes in tooth axis and more movement of root apexes. 4. Comparing the degree of root resorption between bracket types, patients who had used standard brackets showed more apical root loss than patients who had used straight brackets. 5. The most frequent degree of root resorption observed in standard bracket patients was second degree, followed by first degree and third degree. The most frequent degree of root resorption observed in straight bracket patients was zero degree, followed by first, second degree and third degree.

• Journal of the korean academy of Pediatric Dentistry
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• v.43 no.3
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• pp.246-253
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• 2016

The optimal time for the removal of supernumerary teeth can be divided into two groups; early removal and late removal. While each group has its own advantages, the effects on maxillary central incisor can be significant. The purpose of this study was to determine the ideal time for the removal of the supernumerary teeth by evaluating 166 patients for three months after surgical removal of supernumerary teeth. Relatively young patients in early Hellman's dental stage with less developed or unerupted maxillary central incisor had less midline deviation. No statistical significance was found in diastema, rotation of the maxillary incisors and their changes during a follow-up period. Removal of supernumerary teeth should be considered as a preventative measure prior to eruption of the maxillary incisors when the midline deviation is observed in panoramic radiographic examination. This study will be useful in determining the optimal time for the removal of supernumerary teeth depending on the location of the maxillary incisors. This study will be informative on deciding the optimal time to remove the supernumerary teeth depending on the various positions of the maxillary central incisor. (this sentence is better to use)

• 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.

• Journal of the korean academy of Pediatric Dentistry
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• v.46 no.1
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• pp.10-20
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• 2019

Individual dental age is used as an index of chronological age estimation and is an important indicator of the child's growth stage. Dental age does change greatly over time, but it changes constantly. And updating information about this change is important. The purpose of this study was to provide information about tooth eruption stage using diagnostic model analysis and to investigate tooth eruption sequence and estimate chronological age based on this information. Tooth eruption stages were measured on a diagnostic model from 488 patients in 5 - 13 year old children. Based on the information on eruption stage, eruption sequence in maxilla was first permanent molar, central incisor, lateral incisor, first premolar, canine, second premolar and second permanent molar. Eruption sequence in mandible was first permanent molar, central incisor, lateral incisor, canine, first premolar, second premolar and second permanent molar. There were significant differences between males and females in the eruption stage of canine, first and second premolar, and second molar at several ages. The chronological age of male and female was estimated by the coefficient of determination of 0.816, 0.826 respectively.

• The korean journal of orthodontics
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• v.12 no.1
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• pp.27-30
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• 1982

The growth changes in position of upper and lower jaws, incisal inclination in relation to inferior cranial base have been described. Twenty five males was studied quantitavely by means of serial cephalometric reontgenogram from seven to thirteen years of age. The findings seem to warrant the following conclusions: 1. Growth change in anteroposterior relationship of upper and lower jaws to the anterior cranial base showed very little change before eleven years of age but axial inclination of incisal teeth tended to become labiaization in relation to the anterior cranial base. 2. kiter eleven years of age, there wasn't nearly labialization of incisal teeth but jaw prognathism occurred a little in relation to the anterior cranial base.

• The korean journal of orthodontics
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• v.24 no.1 s.44
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• pp.149-159
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• 1994

The purposes of present study were to evaluate changes in models and lateral cephalometric head films during orthodontic treatment and to compare the amount of incisal retraction and anterior movement of molars with the two approaches of the retraction method of canine(sectional canine retractions vs sliding canine retractions) and the anchorage management(head gears vs no head gears, transpalatal arches vs no transpalatal arches and lingual arches vs no lingual arches) and to evaluate changes during orthodontic treatment in models with relation to lateral cephalometric head films. 67 Korean women with Angle's Class I bialveolar protrusion were selected, whose initial chronologic age was above 16 yrs. Models and lateral cephalometric head films were taken before and after orthodontic treatment with four bicuspid extraction. the results were obtained as follows. 1. Significant decreases were observed in intermolar width, arch length and arch perimeter of maxilla and mandible but significant difference was not observed in intercanine width of maxilla and mandible during treatment period. 2. The linear change of the upper incisor to upper lip was 2.84:1 and the linear change of the lower incisor to lower lip was 1.45:1 3. There were no significant differences between the two groups(sectional canine retractions vs sliding canine retractions), the !we groups(transpalatal arches vs no transpalatal arches) and the two groups(lingual arches vs no lingual arches) in the amount of incisal retraction and anterior movement of molars. There were a greater amount of maxillary incisal retraction and a lesser amount of anterior movement of maxillary molars with the use of head gears than no use of head gears. 4. Changes during orthodontic treatment in models with relation to lateral cephalometric head films were obtained as follows : 1) Maxilla Central incisors were moved 3.79mm backward, canines were moved 0.22mm laterally and 3.70mm backward, and molars were moved 0.535mm medially and 2.29mm forward. 2) Mandible Central incisors were moved 3.04mm backward, canines were moved 0.145mm laterally and 3.92mm backward, and molars were moved 0.755mm medially and 1.77mm forward.