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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 2020-09-25

      Positional changes in the mandibular proximal segment after intraoral vertical ramus osteotomy: Surgery-first approach versus conventional approach

      Seoyeon Jung , Yunjin Choi, Jung-Hyun Park, Young-Soo Jung, Hyoung-Seon Baik

      Abstract : Objective: To compare postoperative positional changes in the mandibular proximal segment between the conventional orthognathic surgery (CS) and the surgery-first approach (SF) using intraoral vertical ramus osteotomy (IVRO) in patients with Class III malocclusion. Methods: Thirty-eight patients with skeletal Class III malocclusion who underwent bimaxillary surgery were divided into two groups according to the use of preoperative orthodontic treatment: CS group (n = 18) and SF group (n = 20). Skeletal changes in both groups were measured using computed tomography before (T0), 2 days after (T1), and 1 year after (T2) the surgery. Three-dimensional (3D) angular changes in the mandibular proximal segment, condylar position, and maxillomandibular landmarks were assessed. Results: The mean amounts of mandibular setback and maxillary posterior impaction were similar in both groups. At T2, the posterior portion of the mandible moved upward in both groups. In the SF group, the anterior portion of the mandible moved upward by a mean distance of 0.9 ± 1.0 mm, which was statistically significant (p < 0.001). There were significant between-group differences in occlusal changes (p < 0.001) as well as in overjet and overbite. However, there were no significant between-group differences in proximal segment variables. Conclusions: Despite postoperative occlusal changes, positional changes in the mandibular proximal segment and the position of the condyles were similar between CS and SF, which suggested that SF using IVRO achieved satisfactory postoperative stability. If active physiotherapy is conducted, the proximal segment can be adapted in the physiological position regardless of the occlusal changes.

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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

      Three-dimensional surgical accuracy between virtually planned and actual surgical movements of the maxilla in two-jaw orthognathic surgery

      Mihee Hong , Myung-Jin Kim, Hye Jung Shin, Heon Jae Cho, Seung-Hak Baek

      Abstract : Objective: To investigate the three-dimensional (3D) surgical accuracy between virtually planned and actual surgical movements (SM) of the maxilla in twojaw orthognathic surgery. Methods: The sample consisted of 15 skeletal Class III patients who underwent two-jaw orthognathic surgery performed by a single surgeon using a virtual surgical simulation (VSS) software. The 3D cone-beam computed tomography (CBCT) images were obtained before (T0) and after surgery (T1). After merging the dental cast image onto the T0 CBCT image, VSS was performed. SM were classified into midline correction (anterior and posterior), advancement, setback, anterior elongation, and impaction (total and posterior). The landmarks were the midpoint between the central incisors, the mesiobuccal cusp tip (MBCT) of both first molars, and the midpoint of the two MBCTs. The amount and direction of SM by VSS and actual surgery were measured using 3D coordinates of the landmarks. Discrepancies less than 1 mm between VSS and T1 landmarks indicated a precise outcome. The surgical achievement percentage (SAP, [amount of movement in actual surgery/ amount of movement in VSS] × 100) (%) and precision percentage (PP, [number of patients with precise outcome/number of total patients] × 100) (%) were compared among SM types using Fisher’s exact and Kruskal–Wallis tests. Results: Overall mean discrepancy between VSS and actual surgery, SAP, and PP were 0.13 mm, 89.9%, and 68.3%, respectively. There was no significant difference in the SAP and PP values among the seven SM types (all p > 0.05). Conclusions: VSS could be considered as an effective tool for increasing surgical accuracy.

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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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    • Brief Report l 2020-09-25

      The six geometries revisited

      Austin Kang , Marino Musilli, Mauro Farella

      Abstract : Forces and moments delivered by a straight wire connecting two orthodontic brackets are statically indeterminate and cannot be estimated using the classical equations of static equilibrium. To identify the mechanics of such two-bracket systems, Burstone and Koenig used the principles of linear beam theory to estimate the resulting force systems. In the original publication, however, it remains unclear how the force systems were calculated because no reference or computational details on the underlying principles have been provided. Using the moment carry-over principle and the relative angulation of the brackets, a formula was derived to calculate the relative moments of the two brackets. Because of the moment equilibrium, the vertical forces that exist as a forcecouple on the two brackets can also be calculated. The accuracy of the proposed approach can be validated using previously published empirical data.

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    • Original Article l 2020-09-25

      Treatment modalities for Korean patients with unilateral hemifacial microsomia according to Pruzansky–Kaban types and growth stages

      Il-Hyung Yang , Jee Hyeok Chung , Sunjin Yim, Il-Sik Cho, Sukwha Kim, Jin-Young Choi, Jong-Ho Lee, Myung-Jin Kim, Seung-Hak Baek

      Abstract : Objective: To investigate the treatment modalities (Tx-Mods) for patients with unilateral hemifacial microsomia (UHFM) according to Pruzansky–Kaban types and growth stages. Methods: The samples consisted of 82 Korean UHFM patients. Tx-Mods were defined as follows: Tx-Mod-1, growth observation due to mild facial asymmetry; Tx-Mod-2, unilateral functional appliance; Tx- Mod-3, fixed orthodontic treatment; Tx-Mod-4, growth observation due to a definite need for surgical intervention; Tx-Mod-5, unilateral mandibular or bimaxillary distraction osteogenesis (DO); Tx-Mod-6, maxillary fixation using LeFort I osteotomy and mandibular DO/sagittal split ramus osteotomy; Tx- Mod-7, orthognathic surgery; and Tx-Mod-8, costochondral grafting. The type and frequency of Tx-Mod, the number of patients who underwent surgical procedures, and the number of surgeries that each patient underwent, were investigated. Results: The degree of invasiveness and complexity of Tx-Mod increased, with an increase in treatment stage and Pruzansky–Kaban type (initial < final; [I, IIa] < [IIb, III], all p < 0.001). The percentage of patients who underwent surgical procedures increased up to 4.2 times, with an increase in the Pruzansky–Kaban type (I, 24.1%; IIa, 47.1%; IIb, 84.4%; III, 100%; p < 0.001). However, the mean number of surgical procedures that each patient underwent showed a tendency of increase according to the Pruzansky–Kaban types (I, n = 1.1; IIa, n = 1.5; IIb, n = 1.6; III, n = 2.3; p > 0.05). Conclusions: These findings might be used as basic guidelines for successful treatment planning and prognosis prediction in UHFM patients.

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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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    • 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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    • Case Report l 2020-03-25

      Protraction of mandibular molars through a severely atrophic edentulous space in a case of juvenile periodontitis

      Jian-chao Wu, Yu-ting Zheng, and Yi-jun Dai

      Abstract : Moving the mandibular posterior teeth into a severely atrophic edentulous space is a challenge. A carefully designed force-and-moment system that results in bodily protraction of the posterior teeth with balanced bone resorption and apposition is needed in such cases. This report describes the treatment of a 19-year-old woman with missing mandibular first molars due to juvenile periodontitis. Miniscrews were used as absolute anchorage during protraction of the mandibular second and third molars. Bodily mesial movement of the mandibular second and third molars was achieved over a distance of 11 to 17 mm after 39 months of orthodontic treatment.

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Journal Info.

January, 2021
Vol.51 No.1

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