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KJO Korean Journal of Orthodontics

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pISSN 2234-7518
eISSN 2005-372X
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    • Case Report l 2020-01-25

      Distalization with a modified C-palatal plate for severe upper crowding and a missing lower incisor

      Jae Hyun Park, Traci Saito, Sun Kyong Yoo, Mohammed Alfaifi, and Yoon-Ah Kook

      Abstract : This case report presents the orthodontic treatment of a 25-year-old patient with skeletal Class II and severe maxillary arch crowding, moderate mandibular arch crowding, anterior crossbite, and a missing lower incisor. He was treated with molar distalization using a modified C-palatal plate and temporary anchorage devices to create sufficient space for retraction. The total treatment duration was 21 months. After treatment, his occlusion and smile esthetics showed significant improvement. The modified C-palatal plate represents a treatment modality that enhances the prospects of non-extraction treatment and reduces the need for extraction.

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    • Original Article l 2020-03-25

      Immediate effects of mandibular posterior displacement on the pharyngeal airway space: A preliminary study

      Yeonju Choi, Yong-Il Kim, Seong-Sik Kim, Soo-Byung Park, Woo-Sung Son and Sung-Hun Kim

      Abstract : ObjectiveThis study aimed to evaluate the immediate effects of mandibular posterior displacement on the pharyngeal airway space (PAS) by using cephalometric evaluations and to investigate how the surrounding structures are schematically involved.MethodsIn this retrospective study, 38 subjects with functional Class III malocclusion and two lateral cephalograms were selected. The first lateral cephalogram was taken with the mandible in the habitual occlusal position, and the second in anterior edge-to-edge bite. Paired t-test was used to analyze changes in the PAS, hyoid bone, tongue, and soft palate, followed by mandibular posterior displacement. Pearson's correlation analysis was used to determine the relationship between the amount of mandibular posterior displacement and other variables.ResultsA statistically significant decrease was observed in the PAS following mandibular posterior displacement. Along with mandibular posterior displacement, the tongue decreased in length (p < 0.001) and increased in height (p < 0.05), while the soft palate increased in length, decreased in thickness, and was posteriorly displaced (p < 0.001). The hyoid bone was also posteriorly displaced (p < 0.05). There was no correlation between the amount of mandibular posterior displacement and the measured variables.ConclusionsThe PAS showed a statistically significant decrease following mandibular posterior displacement, which was a consequence of retraction of the surrounding structures. However, there were individual variances between the amount of mandibular posterior displacement and the measured variables.

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    • Original Article l 2020-03-25

      Changes in maximum lip-closing force after extraction and nonextraction orthodontic treatments

      Tae-Hyun Choi, So-Hyun Kim, Cheul Kim, Yoon-Ah Kook, Brent E. Larson, and Nam-Ki Lee

      Abstract : ObjectiveThe aims of the present study were to evaluate the changes in the maximum lip-closing force (MLF) after orthodontic treatment with or without premolar extractions and verify the correlation of these changes with dentoskeletal changes.MethodsIn total, 17 women who underwent nonextraction orthodontic treatment and 15 women who underwent orthodontic treatment with extraction of all four first premolars were included in this retrospective study. For all patients, lateral cephalograms and dental models were measured before (T0) and after (T1) treatment. In addition, MLF was measured at both time points using the Lip De Cum LDC-110R? device. Statistical analyses were performed to evaluate changes in clinical variables and MLF and their correlations.ResultsBoth groups showed similar skeletal patterns, although the extraction group showed greater proclination of the maxillary and mandibular incisors and lip protrusion compared to the nonextraction group at T0. MLF at T0 was comparable between the two groups. The reduction in the arch width and depth and incisor retroclination from T0 to T1 were more pronounced in the extraction group than in the nonextraction group. MLF in the extraction group significantly increased during the treatment period, and this increase was significantly greater than that in the nonextraction group. The increase in MLF was found to be correlated with the increase in the interincisal angle and decrease in the intermolar width, arch depth, and incisor?mandibular plane angle.ConclusionsThis study suggests that MLF increases to a greater extent during extraction orthodontic treatment than during nonextraction orthodontic treatment.

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    • Original Article l 2021-01-25

      Part II. What drives Korean adults to seek orthodontic treatment: Factors contributing to orthodontic treatment decisions

      Min-Hee Oh , Ae-Hyun Park , MinSoo Kim, Eun-A Kim, Jin-Hyoung Cho

      Abstract : Objective: This study aimed to identify the perceptions of orthodontic treatment among Korean adults and determine the factors that drive them to seek orthodontic treatment. Methods: A total of 2,321 adults aged 19–64 years were surveyed using an internet research system from a specialized research company. The participants were divided into the following groups based on their experience of and willingness to undergo orthodontic treatment: experience, acceptance, and non-acceptance groups. The characteristics of the participants were compared using analysis of variance with post-hoc analysis. Multinomial logistic regression analysis was performed in all three models with the non-acceptance group as a reference. Results: In terms of demographic characteristics, age, gender, marital status, and education had significant influences on orthodontic treatment decisions in adults in the experience and acceptance groups (p < 0.001). When all the factors were analyzed, age, marital status, past dental treatment experience, regular oral examinations, demand for orthodontic treatment, optimal treatment period, health insurance coverage, information on orthodontic treatments, perceptions regarding orthodontic treatment, and psychosocial impact of dental esthetics significantly influenced orthodontic treatment decisions in adults in the experience and acceptance groups (p < 0.001). Conclusions: These findings suggest that various factors influence orthodontic treatment decisions in adults. Individuals who seek orthodontic treatment were found to undergo more regular dental treatment and oral examination than those who did not. They also had a better perception of orthodontic treatment and more negative values for the psychosocial impact of dental esthetics.

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    • Original Article l 2021-03-25

      Evaluation of a multi-stage convolutional neural network-based fully automated landmark identification system using cone-beam computed tomographysynthesized posteroanterior cephalometric images

      Min-Jung Kim , Yi Liu, Song Hee Oh, Hyo-Won Ahn, Seong-Hun Kim , Gerald Nelson

      Abstract : Objective: To evaluate the accuracy of a multi-stage convolutional neural network (CNN) model-based automated identification system for posteroanterior (PA) cephalometric landmarks. Methods: The multi-stage CNN model was implemented with a personal computer. A total of 430 PA-cephalograms synthesized from cone-beam computed tomography scans (CBCT-PA) were selected as samples. Twenty-three landmarks used for Tweemac analysis were manually identified on all CBCT-PA images by a single examiner. Intra-examiner reproducibility was confirmed by repeating the identification on 85 randomly selected images, which were subsequently set as test data, with a two-week interval before training. For initial learning stage of the multi-stage CNN model, the data from 345 of 430 CBCT-PA images were used, after which the multi-stage CNN model was tested with previous 85 images. The first manual identification on these 85 images was set as a truth ground. The mean radial error (MRE) and successful detection rate (SDR) were calculated to evaluate the errors in manual identification and artificial intelligence (AI) prediction. Results: The AI showed an average MRE of 2.23 ± 2.02 mm with an SDR of 60.88% for errors of 2 mm or lower. However, in a comparison of the repetitive task, the AI predicted landmarks at the same position, while the MRE for the repeated manual identification was 1.31 ± 0.94 mm. Conclusions: Automated identification for CBCT-synthesized PA cephalometric landmarks did not sufficiently achieve the clinically favorable error range of less than 2 mm. However, AI landmark identification on PA cephalograms showed better consistency than manual identification.

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    • Original Article l 2020-03-25

      Sex-, growth pattern-, and growth status-related variability in maxillary and mandibular buccal cortical thickness and density

      Sydney Schneider, Vaibhav Gandhi, Madhur Upadhyay, Veerasathpurush Allareddy, Aditya Tadinada, and Sumit Yadav

      Abstract : ObjectiveThe primary objective of this study was to quantitatively analyze the bone parameters (thickness and density) at four different interdental areas from the distal region of the canine to the mesial region of the second molar in the maxilla and the mandible. The secondary aim was to compare and contrast the bone parameters at these specific locations in terms of sex, growth status, and facial type.MethodsThis retrospective cone-beam computed tomography (CBCT) study reviewed 290 CBCT images of patients seeking orthodontic treatment. Cortical bone thickness in millimeters (mm) and density in pixel intensity value were measured for the regions (1) between the canine and first premolar, (2) between the first and second premolars, (3) between the second premolar and first molar, and (4) between the first and second molars. At each location, the bone thickness and density were measured at distances of 2, 6, and 10 mm from the alveolar crest.ResultsThe sex comparison (male vs. female) in cortical bone thickness showed no significant difference (p > 0.001). The bone density in growing subjects was significantly (p < 0.001) lower than that in non-growing subjects for most locations. There was no significant difference (p > 0.001) in bone parameters in relation to facial pattern in the maxilla and mandible for most sites.ConclusionsThere was no significant sex-related difference in cortical bone thickness. The buccal cortical bone density was higher in females than in males. Bone parameters were similar for subjects with hyperdivergent, hypodivergent, and normodivergent facial patterns.

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    • Original Article l 2021-03-25

      Relationship between rotational disc displacement of the temporomandibular joint and the dentoskeletal morphology

      So-Hyun Park , Won-Jeong Han, Dong-Hwa Chung, Jung-Sub An, Sug-Joon Ahn

      Abstract : Objective: The purpose of this study was to evaluate the relationship between rotational disk displacement (DD) of the temporomandibular joint (TMJ) and the dentoskeletal morphology. Methods: Women aged > 17 years were included in this study. Each subject had a primary complaint of malocclusion and underwent routine cephalometric examinations. They were divided into five groups according to the findings on sagittal and coronal magnetic resonance images of their TMJs: bilateral normal disk position, bilateral anterior DD with reduction (ADDR), bilateral rotational DD with reduction (RDDR), bilateral anterior DD without reduction (ADDNR), and bilateral rotational DD without reduction (RDDNR). Twenty-three cephalometric variables were analyzed, and the Kruskal–Wallis test was used to evaluate differences in the dentoskeletal morphology among the five groups. Results: Patients with TMJ DD exhibited a hyperdivergent pattern with a retrognathic mandible, unlike those with a normal disk position. These specific skeletal characteristics were more severe in patients exhibiting DD without reduction than in those with reduction, regardless of the presence of rotational DD. Rotational DD significantly influenced horizontal and vertical skeletal patterns only in the stage of DD with reduction, and the mandible exhibited a more backward position and rotation in patients with RDDR than in those with ADDR. However, there were no significant dentoskeletal differences between ADDNR and RDDNR. Conclusions: The results of this study suggest that rotational DD of TMJ plays an important role in the dentoskeletal morphology, particularly in patients showing DD with reduction.

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    • Original Article l 2019-11-25

      Predictors of midpalatal suture expansion by miniscrew-assisted rapid palatal expansion in young adults: A preliminary study

      Hyerin Shin, Chung-Ju Hwang, Kee-Joon Lee, Yoon Jeong Choi, Sang-Sun Han, and Hyung Seog Yu

      Abstract : ObjectiveWe sought to determine the predictors of midpalatal suture expansion by miniscrew-assisted rapid palatal expansion (MARPE) in young adults.MethodsThe following variables were selected as possible predictors: chronological age, palate length and depth, midpalatal suture maturation (MPSM) stage, midpalatal suture density (MPSD) ratio, the sella-nasion (SN)-mandibular plane (MP) angle as an indicator of the vertical skeletal pattern, and the point A-nasion-point B (ANB) angle for anteroposterior skeletal classification. For 31 patients (mean age, 22.52 years) who underwent MARPE treatment, palate length and depth, MPSM stage and MPSD ratio from the initial cone-beam computed tomography images, and the SN-MP angle and ANB angle from lateral cephalograms were assessed. The midpalatal suture opening ratio was calculated from the midpalatal suture opening width measured in periapical radiographs and the MARPE screw expansion. Statistical analyses of correlations were performed for the entire patient group of 31 subjects and subgroups categorized by sex, vertical skeletal pattern, and anteroposterior skeletal classification.ResultsIn the entire patient group, the midpalatal suture opening ratio showed statistically significant negative correlations with age, palate length, and MPSM stage (r = −0.506, −0.494, and −0.746, respectively, all p < 0.01). In subgroup analyses, a strong negative correlation was observed with the palate depth in the skeletal Class II subgroup (r = −0.900, p < 0.05).ConclusionsThe findings of this study indicated that age, palate length, and MPSM stage can be predictors of midpalatal suture expansion by MARPE in young adults.

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    • Original Article l 2021-01-25

      Evaluation of mandibular buccal shelf characteristics in the Colombian population: A cone-beam computed tomography study

      Natalia Escobar-Correa , Maria Antonia Ramírez-Bustamante, Luis Alejandro Sánchez-Uribe, Juan Carlos Upegui-Zea, Patricia Vergara-Villarreal, Diana Milena Ramírez-Ossa

      Abstract : Objective: To evaluate the mandibular buccal shelf (MBS) in terms of the angulation and bone depth and thickness according to sex, age, and sagittal and vertical skeletal patterns in a Colombian population using cone-beam computed tomography (CBCT). Accordingly, the optimal site for miniscrew insertion in this area was determined. Methods: This descriptive, retrospective study included 64 hemi-arches of 34 patients. On CBCT images, the angulation, buccal bone depth (4 and 6 mm from the cementoenamel junction [CEJ] of MBS), and buccal bone thickness (6 and 11 mm from the CEJ of MBS) were measured at the mesial and distal roots of the mandibular first and second molars. Results: There were no statistically significant differences in the angulation, depth, and thickness of MBS between male and female patients. The values for the bone around the distal root of the mandibular second molar were significantly greater than the other values. The osseous characteristics were significantly better in participants aged 16–24 years. Class III patients exhibited the best osseous characteristics, with the bone depth at 6 mm being significantly different from that in Class I and Class II patients. Although values tended to be greater in patients with low angles, the difference was not statistically significant. Conclusions: MBS provides an optimal bone surface for miniscrew insertion, with better osseous characteristics at the distal root of the mandibular second molar, 4 mm from CEJ. Adolescent patients, Class III patients, and patients with a low angle exhibit the most favorable osseous characteristics in the MBS area.

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    • Original Article l 2019-11-25

      Type of tooth movement during en masse retraction of the maxillary anterior teeth using labial versus lingual biocreative therapy in adults: A randomized clinical trial

      Mais M. Sadek, Noha E. Sabet, and Islam T. Hassan

      Abstract : ObjectiveThe objective of this two-arm parallel trial was to compare the type of tooth movement during en masse retraction of the maxillary anterior teeth using labial versus lingual biocreative therapy.MethodsTwenty-eight subjects were randomized in a 1 : 1 ratio to either the labial or lingual group. En masse anterior retraction was performed using labial biocreative therapy in group A and lingual biocreative therapy in group B. Cone beam computed tomography scans were taken before and after retraction and the primary outcome was the type of tooth movement during anterior retraction. Data were analyzed using paired t-tests for comparisons within each group and independent-sample t-test for comparison of the mean treatment changes between the two groups.ResultsSignificant differences were found between the two groups in relation to the type of tooth movement (labiolingual inclination of the central incisor; mean difference, 5.85 ± 1.85°). The canine showed significant distal tipping in the lingual group (mean difference, 6.98 ± 1.25°). The canine was significantly more intruded in the lingual group (mean difference, 1.67 ± 0.49 mm). Good anchorage control and significant soft tissue changes occurred in both groups. No serious adverse effects were detected.ConclusionsWith a 10-mm retraction hook, the labial biocreative technique with the reverse curve overlay provided anterior retraction with good torque control, while in the lingual group, anterior retraction occurred with controlled tipping movement with significant distal tipping and intrusion of the canine (trial registration: The trial was registered at []).

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Journal Info.

March, 2021
Vol.51 No.2

Frequency: 6 times

Journal Impact Factor

  • 1.476
    2018 IF

  • 1.523
    5-Year IF

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Clinical Journal of Korean Association of Orthodontists