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KJO Korean Journal of Orthodontics

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pISSN 2234-7518
eISSN 2005-372X
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    • Original Article l 2020-11-25

      Comparison of slot sizes and parallelism of metal brackets manufactured through metal injection molding and computerized numerical control

      Jae-Sung Park , In-Tae Song, Jae-Hee Bae, Soo-Min Gil, Kyung-Hwa Kang

      Abstract : Objective: To investigate and compare the slot sizes and parallelism of metal injection molding (MIM) and computerized numerical control (CNC) brackets. Methods: The following four MIM bracket series with 0.022-inch (in) slots were selected for investigation: Di MIM mini Twin (Ortho Organizers), Mini Diamond Roth (Ormco), Gemini MBT (3M Unitek), and Formula R Roth (Tomy). The following four CNC bracket series with 0.022-in slots were selected for investigation: Econoline MBT (Adenta), Legend mini MBT (GC Orthodontics), Crown mini MBT (Adenta), and Evolve MBT (DB Orthodontics). The slot dimensions were measured using an optical microscope (XTCam-D310M; Mitutoyo) with a resolution of 1 μm. The results were statistically analyzed using one-way analysis of variance and the Tukey post-hoc test with a significance level of 0.05. Results: The results indicated that all the investigated slot sizes were oversized with respect to the manufacturers’ specifications (0.022 in). Among the eight bracket series, the Di MIM bracket (MIM) was the most oversized by 10.4%, whereas the Evolve bracket (CNC) was the least oversized by 2.6%. The slots in seven of the bracket series had divergent walls instead of parallel ones. The Evolve bracket alone had parallel slot walls. Conclusions: Regardless of the manufacturing method, all the slot sizes of the brackets investigated in this study were significantly oversized; most of the slot walls were nonparallel, except for those of the Evolve bracket. This study could not establish that the CNC method was more accurate than the MIM method in manufacturing bracket slots.

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    • Original Article l 2020-05-25

      Evaluation of cephalometric characteristics and skeletal maturation of the cervical vertebrae and hand-wrist in girls with central precocious puberty

      Sung-Tae Kang , Sung-Hwan Choi, Kyung-Ho Kim, Chung-Ju Hwang

      Abstract : Objective: This study aimed to evaluate the differences in cephalometric characteristics and skeletal maturation in girls with central precocious puberty (CPP) via lateral and hand-wrist radiographs. We also aimed to identify the indicators that are most effective for determining skeletal maturity in these patients. Methods: The study included 70 Korean girls (mean age, 8.5 ± 0.5 years) diagnosed with CPP at the Department of Pediatrics, and 48 normal healthy age-matched girls who visited the Department of Orthodontics and had no history of hormone treatment or growth problems. Skeletal maturation was evaluated using lateral cephalometric and hand-wrist radiographs using cervical vertebrae maturation indicators (CVMI) and skeletal maturity indicators (SMI). Results: The mean mandibular plane angle was smaller in the CPP group than in the control group (35.8° ± 4.9° vs. 39.0° ± 6.5°), resulting in greater posterior facial height (p = 0.003). SMI was significantly greater in the CPP group (3.5 ± 1.4 vs. 2.0 ± 1.0) than in the control group (p = 0.001) and was significantly associated with CPP (r = 0.492; p = 0.001), whereas CVMI was not. Conclusions: In comparison with the control group, the CPP group exhibited a smaller mandibular plane angle, greater posterior facial height, and greater skeletal maturation. SMI may be more suitable than CVMI for determining skeletal maturation in CPP. Hand-wrist radiography is recommended in addition to lateral cephalogram for predicting growth in girls with CPP.

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    • Original Article l 2020-09-25

      Short-term treatment effects produced by rapid maxillary expansion evaluated with computed tomography: A systematic review with meta-analysis

      Antonino Lo Giudice , Paola Spinuzza, Lorenzo Rustico, Gabriele Messina, Riccardo Nucera

      Abstract : Objective: To identify the available evidence on the effects of rapid maxillary expansion (RME) with three-dimensional imaging and provide meta-analytic data from studies assessing the outcomes using computed tomography. Methods: Eleven electronic databases were searched, and prospective case series were selected. Two authors screened all titles and abstracts and assessed full texts of the remaining articles. Seventeen case series were included in the quantitative synthesis. Seven outcomes were investigated: nasal cavity width, maxillary basal bone width, alveolar buccal crest width, alveolar palatal crest width, inter-molar crown width, inter-molar root apex width, and buccopalatal molar inclination. The outcomes were investigated at two-time points: postexpansion (2–6 weeks) and post-retention (4–8 months). Mean differences and 95% confidence intervals were used to summarize and combine the data. Results: All the investigated outcomes showed significant differences postexpansion (maxillary basal bone width, +2.46 mm; nasal cavity width, +1.95 mm; alveolar buccal crest width, +3.90 mm; alveolar palatal crest width, +3.09 mm; intermolar crown width, +5.69 mm; inter-molar root apex width, +2.85 mm; and dental tipping, +3.75°) and post-retention (maxillary basal bone width, +2.21 mm; nasal cavity width, +1.55 mm; alveolar buccal crest width, +3.57 mm; alveolar palatal crest width, +3.32 mm; inter-molar crown width, +5.43 mm; inter-molar root apex width, +4.75 mm; and dental tipping, 2.22°) compared to pre-expansion. Conclusions: After RME, skeletal expansion of the nasomaxillary complex was greater in most caudal structures. Maxillary basal bone showed 10% post-retention relapse. During retention period, uprighting of maxillary molars occurred.

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    • Original Article l 2020-09-25

      Stability of bimaxillary surgery involving intraoral vertical ramus osteotomy with or without presurgical miniscrew-assisted rapid palatal expansion in adult patients with skeletal Class III malocclusion

      Yoon-Soo Ahn , Sung-Hwan Choi , Kee-Joon Lee, Young-Soo Jung, Hyoung-Seon Baik, Hyung-Seog Yu

      Abstract : 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.

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    • Original Article l 2020-11-25

      Antifibrotic effects of sulforaphane treatment on gingival elasticity reduces orthodontic relapse after rotational tooth movement in beagle dogs

      Kyong-Nim Kim , Jue-Young Kim, Jung-Yul Cha, Sung-Hwan Choi, Jin Kim, Sung-Won Cho, Chung-Ju Hwang

      Abstract : Objective: Increased gingival elasticity has been implicated as the cause of relapse following orthodontic rotational tooth movement and approaches to reduce relapse are limited. This study aimed to investigate the effects of sulforaphane (SFN), an inhibitor of osteoclastogenesis, on gene expression in gingival fibroblasts and relapse after rotational tooth movement in beagle dogs. Methods: The lower lateral incisors of five beagle dogs were rotated. SFN or dimethylsulfoxide (DMSO) were injected into the supra-alveolar gingiva of the experimental and control group, respectively, and the effect of SFN on relapse tendency was evaluated. Changes in mRNA expression of extracellular matrix components associated with gingival elasticity in beagles were investigated by real-time polymerase chain reaction. Morphology and arrangement of collagen fibers were observed on Masson’s trichrome staining of buccal gingival tissues of experimental and control teeth. Results: SFN reduced the amount and percentage of relapse of orthodontic rotation. It also decreased the gene expression of lysyl oxidase and increased the gene expression of matrix metalloproteinase (MMP) 1 and MMP 12, compared with DMSO control subjects. Histologically, collagen fiber bundles were arranged irregularly and were not well connected in the SFN-treated group, whereas the fibers extended in parallel and perpendicular directions toward the gingiva and alveolar bone in a more regular and well-ordered arrangement in the DMSO-treated group. Conclusions: Our findings demonstrated that SFN treatment may be a promising pharmacologic approach to prevent orthodontic rotational relapse caused by increased gingival elasticity of rotated teeth in beagle dogs.

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    • Original Article l 2021-03-25

      Effect of micro-osteoperforations on external apical root resorption: A randomized controlled trial

      Azaitun Akma Shahrin , Sarah Haniza Abdul Ghani, Noraina Hafizan Norman

      Abstract : Objective: This study aimed to investigate the effect of micro-osteoperforations (MOPs) on external apical root resorption (EARR) during the initial orthodontic alignment phase of maxillary anterior crowding. Methods: Thirty patients (25 females, 5 males; mean age, 22.66 ± 3.27 years) who presented with moderate crowding of the upper labial segment and underwent extraction-based fixed appliance treatment were recruited. They were randomly allocated to receive adjunctive therapy with MOPs (n = 15) or treatment with fixed appliances only (control group; n = 15). EARR was measured from long-cone periapical radiographs taken at the start and the sixth month of treatment. A correction factor for the enlargement difference was used to calculate EARR. Data were analyzed with descriptive statistics and repeated-measures analysis of variance. Results: The mean root lengths of 168 teeth were measured and showed no statistically significant difference (p > 0.05) after six months of fixed appliance treatment in the MOP (mean difference [MD] = 0.13 mm; 95% confidence interval [CI] = −0.10–0.35) and control group (MD = 0.14 mm; 95% CI = −0.10–0.37). Most of the roots in the MOP and control groups (42.86% and 52.38%, respectively) showed only mild resorption. Less than 8% of the roots in both groups (7.14% in the MOP group and 4.76% in the control group) showed moderate resorption. Conclusions: Acceleration of orthodontic tooth movement with adjunctive MOPs therapy during the alignment phase does not exacerbate EARR in patients with moderate crowding of the upper labial segment in comparison with controls.

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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 2020-11-25

      Distribution, side involvement, phenotype and associated anomalies of Korean patients with craniofacial clefts from single university hospitalbased data obtained during 1998–2018

      Jee Hyeok Chung , Sunjin Yim, Il-Sik Cho, Seung-Weon Lim, Il-Hyung Yang, Jeong Hyun Ha, Sukwha Kim, Seung-Hak Baek

      Abstract : Objective: To investigate the distribution, side involvement, phenotype, and associated anomalies of Korean patients with craniofacial clefts (CFC). Methods: The samples consisted of 38 CFC patients, who were treated at Seoul National University Dental Hospital during 1998–2018. The Tessier cleft type, sex, side involvement, phenotype, and associated anomalies were investigated using nonparametric statistical analysis. Results: The three most common types were #7 cleft, followed by #0 cleft and #14 cleft. There was no difference between the frequency of male and female. Patients with #0 cleft exhibited nasal deformity, bony defect, and missing teeth in the premaxilla, midline cleft lip, and eye problems. A patient with #3 cleft (unilateral type) exhibited bilateral cleft lip and alveolus. All patients with #4 cleft were the bilateral type, including a combination of #3 and #4 clefts, and had multiple missing teeth. A patient with #5 cleft (unilateral type) had a posterior openbite. In patients with #7 cleft, the unilateral type was more prevalent than the bilateral type (87.0% vs. 13.0%, p < 0.001). Sixteen patients showed hemifacial microsomia (HFM), Goldenhar syndrome, and unilateral cleft lip and palate (UCLP). There was a significant match in the side involvement of #7 cleft and HFM (87.5%, p < 0.01). Patients with #14 cleft had plagiocephaly, UCLP, or hyperterorbitism. A patient with #30 cleft exhibited tongue tie and missing tooth. Conclusions: Due to the diverse associated craniofacial anomalies in patients with CFC, a multidisciplinary approach involving a well-experienced cooperative team is mandatory for these patients.

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    • Original Article l 2021-01-15

      Force changes associated with differential activation of en-masse retraction and/or intrusion with clear aligners

      Ye Zhu , Wei Hu , Shuo Li

      Abstract : Objective: To investigate the three-dimensional forces created by clear aligners on mandibular teeth during differential activation with en-masse retraction and/or intrusion in vitro. Methods: Six sets of clear aligners were designed for differential en-masse retraction and/or intrusion procedures in a first premolar extraction model. Group A0 was a control group with no activation. Groups A1–5 underwent different degrees of retractions and/or intrusions. Each group consisted of 10 aligners. Aligner forces were measured on a multi-axis force/ torque transducer measurement system in real-time. Results: In the en-masse retraction groups (A1 and A2), lingual and extrusive forces were observed on the incisors; the canines mainly received distal forces; intrusive forces were seen on the second premolars; and the molars received mesial forces. In the enmasse retraction and intrusion groups (A3, A4, and A5), incisors also received lingual and extrusive forces; canines received distal and intrusive forces; mesial and extrusive forces were seen on the second premolars; and the second molars received distal and intrusive forces. The vertical forces on the incisors did not differ significantly among groups A1, A3, and A5. However, the vertical forces on the second premolars reversed from intrusion in group A1 to extrusion in groups A3 and A5. Conclusions: With clear aligners, the “bowing effect” is seen during en-masse anterior teeth retraction and can be partially relieved by performing en-masse retraction accompanied by anterior teeth intrusion. Vertical control of incisors remained unsolved during en-masse retraction, even when intrusive activation was added to the anterior teeth.

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    • Original Article l 2021-03-25

      Differences in mandibular condyle and glenoid fossa morphology in relation to vertical and sagittal skeletal patterns: A cone-beam computed tomography study

      Kyoung Jin Noh , Hyoung-Seon Baik, Sang-Sun Han, Woowon Jang, Yoon Jeong Choi

      Abstract : Objective: This study aimed to evaluate the following null hypothesis: there are no differences in the morphology of the temporomandibular joint (TMJ) structures in relation to vertical and sagittal cephalometric patterns. Methods: This retrospective study was performed with 131 participants showing no TMJ symptoms. The participants were divided into Class I, II, and III groups on the basis of their sagittal cephalometric relationships and into hyperdivergent, normodivergent, and hypodivergent groups on the basis of their vertical cephalometric relationships. The following measurements were performed using cone-beam computed tomography images and compared among the groups: condylar volume, condylar size (width, length, and height), fossa size (length and height), and condyle-to-fossa joint spaces at the anterior, superior, and posterior condylar poles. Results: The null hypothesis was rejected. The Class III group showed larger values for condylar width, condylar height, and fossa height than the Class II group (p < 0.05). Condylar volume and superior joint space in the hyperdivergent group were significantly smaller than those in the other two vertical groups (p < 0.001), whereas fossa length and height were significantly larger in the hyperdivergent group than in the other groups (p < 0.01). The hypodivergent group showed a greater condylar width than the hyperdivergent group (p < 0.01). The sagittal and vertical cephalometric patterns showed statistically significant interactions for fossa length and height. Conclusions: TMJ morphology differed across diverse skeletal cephalometric patterns. The fossa length and height were affected by the interactions of the vertical and sagittal skeletal patterns.

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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