• The korean journal of orthodontics
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• v.52 no.4
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• pp.287-297
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• 2022

Objective: To investigate the pattern of accuracy change in artificial intelligence-assisted landmark identification (LI) using a convolutional neural network (CNN) algorithm in serial lateral cephalograms (Lat-cephs) of Class III (C-III) patients who underwent two-jaw orthognathic surgery. Methods: A total of 3,188 Lat-cephs of C-III patients were allocated into the training and validation sets (3,004 Lat-cephs of 751 patients) and test set (184 Lat-cephs of 46 patients; subdivided into the genioplasty and non-genioplasty groups, n = 23 per group) for LI. Each C-III patient in the test set had four Lat-cephs: initial (T0), pre-surgery (T1, presence of orthodontic brackets [OBs]), post-surgery (T2, presence of OBs and surgical plates and screws [S-PS]), and debonding (T3, presence of S-PS and fixed retainers [FR]). After mean errors of 20 landmarks between human gold standard and the CNN model were calculated, statistical analysis was performed. Results: The total mean error was 1.17 mm without significant difference among the four time-points (T0, 1.20 mm; T1, 1.14 mm; T2, 1.18 mm; T3, 1.15 mm). In comparison of two time-points ([T0, T1] vs. [T2, T3]), ANS, A point, and B point showed an increase in error (p < 0.01, 0.05, 0.01, respectively), while Mx6D and Md6D showeda decrease in error (all p < 0.01). No difference in errors existed at B point, Pogonion, Menton, Md1C, and Md1R between the genioplasty and non-genioplasty groups. Conclusions: The CNN model can be used for LI in serial Lat-cephs despite the presence of OB, S-PS, FR, genioplasty, and bone remodeling.

• The korean journal of orthodontics
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• v.19 no.1 s.27
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• pp.107-122
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• 1989

The purpose of this study was to assess the growth changes of craniofacial complex and to establish Korean norms by McNamara's cephalometric analysis. Lateral cephalograms were obtained from males and females with normal occlusion & acceptable profiles in 9-21 years of age. The lateral cephalograms of males & females in 9-13 years of age were serial cephalometric radiograms which were taken at 2 year interval. 11 landmarks, 10 planes and 3 angles were plotted and measured linearly and angularly. The results were as follows: 1. The author made the tables of means, standard deviations in each item, sex, age. 2. During 9-13 years of age, annual growth increments of effective maxillary length, effective mandibular length and lower anterior facial height were 1.90, 2.89 and 0.99mm. 3. The prediction tabulation was made in an attempt to predict effective mandibular length & lower anterior facial height derived from effective maxillary length.

• The korean journal of orthodontics
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• v.26 no.2 s.55
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• pp.141-151
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• 1996

This study was undertaken to assess the effect of growth on the lips. Not only does lip growth influence the stability of such orthodontic treatment; it also directly influence facial profile, in which the lips have an important part. An understanding of the growth of lips is thus central to a consideration of profile change in orthodontics. By analyzing the serial lateral cephalograms of 15 male and 15 female of 8 years old to 16 yaers old who have normal occlusion. The result of this study were summerized as follows; 1. The largest growth increments in the length of the lips was mod age of 14 in both sexes. 2. The thickness of lips showed lager value for the male than that of the female in the most age group. The lagest growth increments at A point was occured age of 14, while Ls, Li, B point decreased after the age of 10-11. 3. The largest increase in the interval between crest of lower lip and edge of upper incisors was occured between ages 9 and 11 in males. The interval decreased slightly from 8 to 16 years in females. 4. The nasolabial angle decreased slightly from 8 to 16 years in both sexes. 5. The mentolabial angle showed large variation.

• The korean journal of orthodontics
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• v.23 no.2 s.41
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• pp.249-261
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• 1993

This study was conducted to examine the growth change in external nose according to age which plays an important role in determining the facial profile, by analysing the biennial serial lateral cephalograms of 20 males and 20 females of mean 8.5 years old to 16.5 years old who have a normal occlusion. The results of this study were summarized as follows. $\cdot$ Both mean and standard deviation were obtained according to each item, sex and age for the male and female. $\cdot$ Nose heights of the male and female increased with increase in their age. The upper to lower nose height ratio somewhat decreased for both male and female with increase of age. The mean ratio was 3.69 : 1 for the male, respectively, and 3.83 : 1 for the female during this study．$\cdot$ The nose depth indicated the most significant increase of all items according to the increase of age, while the sagittal depth inicated higher value for the female than that of the male in the most age groups. $\cdot$ The nose inclination did not show a remarkable change during this study. $\cdot$ The proportions of growth completed at the earliest age showed the highest percentage for sagittal depth(male : $87.14\%$ & female : $91.29\%$). Also, the male indicated the lowest percentage in lower nose height $(73.04\%)$, while the female did the lowest in nose depth$(79.09\%)$. $\cdot$ There was shown the variable of the greatest correlation between the upper nose inclination and nose depth. $\cdot$ From this study, the whole external nasal growth was occurred downward and forward which was more frequent for forward growth than vertical growth.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.33 no.5
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• pp.407-412
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• 2011

Purpose: The purpose of the present study was to evaluate the postoperative skeletal stability of two-jaw surgery (Le Fort I osteotomy and bilateral sagittal split ramus osteotomy) via surgery first orthodontic treatment (SFOT) in class III malocclusion. Methods: Thirty-two patients who had two-jaw surgery via SFOT were included in this study. Serial lateral cephalograms were obtained before (T0), immediately after (T1), and six months after (T2) surgery. Twelve variables were measured for horizontal and vertical skeletal stability as well as for dental change. All measurements were evaluated statistically by a paired t-test ($P$ <0.05). Results: The mean skeletal changes were $0.1{\pm}2.5$ mm at point A and $-12.0{\pm}7.4$ mm at the pogonion. The mean horizontal relapse was 11.6% at the pogonion, and the mean vertical surgical changes included an upward displacement of $2.1{\pm}7.1$ mm and a forward displacement of $1.4{\pm}4.6$ mm at the pogonion. Upper incisor inclination decreased after surgery and was maintained at T2, and lower incisors were proclined from T1 to T2 by postsurgical orthodontic treatment. Conclusion: Postoperative skeletal stability of two-jaw surgery via surgery first orthodontic treatment in class III malocclusion was clinically acceptable.

• The korean journal of orthodontics
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• v.50 no.5
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• pp.304-313
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• 2020

Objective: The aim of this study was to evaluate the stability of bimaxillary surgery involving bilateral intraoral vertical ramus osteotomy performed with or without presurgical miniscrew-assisted rapid palatal expansion (MARPE) in adult patients with skeletal Class III malocclusion. Methods: A total of 40 adult patients with skeletal Class III malocclusion were retrospectively divided into two groups (n = 20 each) according to the use of MARPE for the correction of transverse maxillomandibular discrepancy during presurgical orthodontic treatment. Serial lateral cephalograms and dental casts were analyzed until 6 months after surgery. Results: Before presurgical orthodontic treatment, there was no significant differences in terms of sex and age between groups. However, the difference of approximately 3.1 mm in the maxillomandibular intermolar width was statistically significant (p < 0.001). Two days after surgery, the mandible had moved backward and upward without any significant intergroup difference. Six months after surgery, the maxillary intercanine (2.7 ± 2.1 mm), interpremolar (3.6 ± 2.4 mm), and intermolar (2.0 ± 1.3 mm) arch widths were significantly increased (p < 0.001) relative to the values before presurgical orthodontic treatment in the MARPE group; these widths were maintained or decreased in the control group. However, there was no significant difference in surgical changes and the postsurgical stability between the two groups. No significant correlations existed between the amount of maxillary expansion and postsurgical mandibular movement. Conclusions: MARPE is useful for stable and nonsurgical expansion of the maxilla in adult patients with skeletal Class III malocclusion who are scheduled for bimaxillary surgery.

• Journal of the korean academy of Pediatric Dentistry
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• v.36 no.3
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• pp.412-419
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• 2009

The purpose of this study was to provide the reference data evaluating the treatment effect of orthopedic appliances. The skeletal and dental growth increments were measured in 24 normal mixed dentition children (boys: 14, girls: 10) by three serial lateral cephalograms: initial mean age: 9${\pm}$1.3 years, mean observation period: 13${\pm}$1.3 months. Cephalometric changes were analysed. The results were as follows: 1. In boys, the maxilla showed forward and downward growth pattern and the mandible showed forward growth pattern (p<0.05). In girls, the maxilla and mandible showed forward and downward growth pattern(p<0.05). 2. Horizontal growth of both maxilla and mandible in girls was superior to those in boys (A point; girls: 2.39mm, boys: 1.26mm, with p<0.05), whereas vertical growth of both maxilla and mandible in boys was similar to those in girls. 3. The change in tooth axis showed labioversion of upper incisor (p<0.01) and comparatively stable lower incisor position.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.43 no.1
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• pp.23-28
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• 2017

Objectives: The purpose of this study is to compare the postoperative stability of conventional orthognathic surgery to a surgery-first orthognathic approach after bilateral sagittal split ramus osteotomy (BSSRO). Materials and Methods: The study included 20 patients who underwent BSSRO for skeletal class III conventional orthognathic surgery and 20 patients who underwent a surgery-first orthognathic approach. Serial lateral cephalograms were analyzed to identify skeletal changes before surgery (T0), immediately after surgery (T1), and after surgery (T2, after 1 year or at debonding). Results: The amount of relapse of the mandible in the conventional orthognathic surgery group from T1 to T2 was $2.23{\pm}0.92mm$ (P<0.01) forward movement and $-0.87{\pm}0.57mm$ (non-significant, NS) upward movement on the basis of point B and $2.54{\pm}1.37mm$ (P<0.01) forward movement and $-1.18{\pm}0.79mm$ (NS) upward movement on the basis of the pogonion (Pog) point. The relapse amount of the mandible in the surgery-first orthognathic approach group from T1 to T2 was $3.49{\pm}1.71mm$ (P<0.01) forward movement and $-1.78{\pm}0.81mm$ (P<0.01) upward movement on the basis of the point B and $4.11{\pm}1.93mm$ (P<0.01) forward movement and $-2.40{\pm}0.98mm$ (P<0.01) upward movement on the basis of the Pog. Conclusion: The greater horizontal and vertical relapse may appear because of counter-clockwise rotation of the mandible in surgery-first orthognathic approach. Therefore, careful planning and skeletal stability should be considered in orthognathic surgery.

• The korean journal of orthodontics
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• v.25 no.5 s.52
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• pp.557-566
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• 1995

Postpubertal craniofacial growth changes were assessed from serial lateral cephalograms taken at which subjects were 16 and 18 years of age. The sample consisted of 19 male and 14 female subjects with no previous orthodontic treatment who had normal occlusion. The craniofacial growth changes of these samples during this study period might be summarized as follows 1. Significant increase in mean maxillary and mandibular length, cranial base length, posterior md anterior facial height were observed at the age period studied in male(P<0.05), however, in female significant increase was observed only mandibular length(Ar-Gn, Ar-Go) and anterior and posterior facial height(P<0.05). 2. Total growth increment of all measumenats were below 1mm in female, but in male, total mandibular(Ar-Gn) growth increment was 2.0mm and those of mandibular tody length, ram length, posterior facial height, and anteior facial height were 1 to 1.54mm and the others were below 1mm 3. A closing, forward rotation of the mandible occured with a significant decrease in mandibular plane angle of $0.61^{\circ}$ in male(P<0.01). 4. Summarized the findings, even though statistically significant growth changes in some dimensions of female were observed, the amount of growth change were very small, however, in male the growth changes of some dimensions associated with mandible were significant and considerable amount.

• The korean journal of orthodontics
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• v.29 no.4 s.75
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• pp.435-443
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• 1999

This study was undertaken to investigate the growth change of genial angle and interrelationship between the growth change of gonial angle and IMPA in the longitudinal data from 7 years to 15 years. By analyzing the serial lateral cephalograms or 15 males and 19 females of 7 years old to 15 yens old who had no abnomality in growth and development and no history of orthodontic treatment, the following conclusion were obtained. 1. Genial angle gradually decreased with aging in 25 children and in 9 children increased or maintained. 2. There was a tendency that children who decreased genial angle with aging showed gradual increase of IMPA and children who increased or maintained gonial angle with aging showed decrease of IMPA. 3. There was a tendency that regardless of the change of gonial angle, interincisal angle decreased with aging.