Korean Journal of Orthodontics最新文献

Objective: This study aimed (1) to compare the effects of clear aligner treatment (CAT) and fixed appliances incorporating temporary anchorage devices (FATADs) on overbite and the vertical position of anterior and posterior teeth in open bite patients; (2) to assess the impact of CAT on increasing overbite and vertical tooth movement; and (3) to evaluate post-treatment stability.

Methods: Electronic searches of Medline, Scopus, Cochrane Central, Embase, and the Virtual Health Library network portal, and manual searches were conducted up to April 2025. Human studies evaluating CAT for open bite correction and reporting pre- and post-treatment overbite (primary outcome) and vertical incisor and molar positions (secondary outcomes), with or without comparison to FATADs, were included. Study quality was assessed using design-appropriate tools.

Results: Of 1,610 identified studies, 10 met the inclusion criteria (four non-randomized controlled trials and six before-and-after studies). CAT increased overbite by 2.77 mm, mainly through upper (0.87 mm) and lower (1.06 mm) incisor extrusion, without significant molar intrusion. Compared with CAT, FATADs achieved greater overbite correction and upper molar intrusion (1.64 mm and 1.88 mm, respectively). CAT showed greater lower incisor extrusion (2.35 mm), with no significant difference in upper incisor position. During retention, CAT maintained stability, with no significant changes in overbite (0.02 mm) or vertical tooth positions.

Conclusions: CAT effectively increases overbite mainly through incisor extrusion but is less effective than FATADs for open bite correction via molar intrusion. The vertical position of the teeth remained stable during the retention period.

Objective: Since categorization of dental crowding is a crucial parameter in orthodontic diagnosis and tooth-extraction decisions, we aimed to develop an automatic system to categorize crowding levels on intraoral photographs without space analysis.

Methods: The Dental Crowding Categorization Network (DCC-Net), consisting of segmentation, extraction, and categorization modules, was proposed and optimized by extracting regions of interest and crown centroids. A multicenter dataset including 1,351 maxillary and 1,253 mandibular intraoral photographs was divided in an 8:2 ratio for model training and internal testing, and an additional 100 photographs were collected for external testing. The ground truth was obtained through measurements by experienced orthodontists using intraoral scanning data. The accuracy, precision, recall, and F1-score of the categorization module were calculated, and heatmaps were obtained for model interpretation. Furthermore, a clinical evaluation was performed to compare the diagnostic accuracy of junior orthodontists with and without the assistance of DCC-Net.

Results: For the maxilla, the categorization accuracy, precision, recall, and F1-score were 0.7232, 0.7447, 0.6793, and 0.6962, respectively, whereas the corresponding values for categorization in the mandible were 0.7352, 0.7506, 0.6723, and 0.7019, respectively. The heatmaps indicated that DCC-Net could identify the dental arches and regions showing malocclusion. In the clinical evaluation, the diagnostic accuracy of junior orthodontists improved with DCC-Net's assistance, increasing by 9.18% for the maxilla and 12.75% for the mandible.

Conclusions: DCC-Net achieved accurate categorization of dental crowding on intraoral photographs. Its rapid predictions may offer insights for guiding tooth extraction in orthodontic treatment, providing valuable reference data for inexperienced orthodontists and improving doctor-patient communication.

Objective: To investigate the frequency of midpalatal suture separation with tooth-and-bone-borne (TBB) and bone-borne (BB) miniscrew-assisted rapid palatal expansion and to compare their skeletal and dentoalveolar effects in young adults.

Methods: This retrospective study included 34 patients (14 male and 20 female) who underwent palatal expansion divided into two groups: TBB group (n = 15; mean age, 22.3 years) and BB group (n = 19; mean age, 21.7 years). Cone-beam computed tomography images were acquired before treatment (T0) and after a 3-month consolidation period (T1). The primary outcomes were the frequency of midpalatal suture separation (%) and skeletal and dentoalveolar changes after expansion. The secondary outcome was the dental expansion ratio (%).

Results: Midpalatal suture separation was observed in 73.3% (11/15) and 73.7% (14/19) of patients in the TBB and BB groups, respectively. Both groups showed comparable increases in skeletal measurements. However, the TBB group demonstrated greater dentoalveolar expansion than the BB group. In addition, the TBB group exhibited greater dental inclination and a greater reduction in the buccal alveolar bone thickness than the BB group. Furthermore, the dental expansion ratio was significantly higher in the TBB group (65.0%) than in the BB group (35.7%, P < 0.001).

Conclusions: Both TBB and BB achieved successful midpalatal suture separation in young adults, with success rates of 73.3% and 73.7%, respectively. Moreover, skeletal expansion outcomes were comparable between the groups. However, dental expansion was greater in the TBB group than in the BB group, with a greater increase in dental inclination.

Objective: To characterize the zygomatico-maxillary suture fusion (ZMSF) from preadolescence to young adulthood.

Methods: A total of 573 subjects (283 males, 290 females; age, 6-18 years) were divided into 26 groups based on sex and age. Three-dimensional computed tomography images were reconstructed and oriented using ON3D software. The cervical vertebrae maturation index (CVMI) and ZMSF stages were identified using 6-stage and 5-stage scoring systems, respectively. The distributions of CVMI stage and ZMSF stage in each group were statistically analyzed.

Results: Females exhibited earlier appearance and a narrower range of onset (CVMI stage-2, ZMSF stage-2), middle (CVMI stage-4, ZMSF stage-3), and completion (CVMI stage-6, ZMSF stage-5), indicating faster skeletal maturation compared to males. Both males and females showed strong positive correlations between age and CVMI stage, between age and ZMSF stage, and between CVMI stage and ZMSF stage (all P < 0.001). The mean ages at ZMSF stage-3 and stage-4 (11.9-14.7 years for males, 9.7-12.6 years for females) may indicate the peak of pubertal growth. Regression equations for ZMSF stage (y), age (a), and CVMI stage (b) were y = -0.508 + (0.169 × a) + (0.509 × b) + (-0.006 × ab) for males and y = -1.227 + (0.285 × a) + (0.804 × b) + (-0.034 × ab) for females. Multivariable ordinal logistic regression analyses indicated that increases in age and progress in CVMI stage were associated with more advanced ZMSF stage, suggesting that ZMSF follows the general skeletal maturation curve.

Conclusions: The ZMSF stages showed strong correlations with age and progression of the CVMI stage.

Objective: Three-dimensional (3D) facial images of autonomous maximal smile (AMS) hold unique value for generating orthodontic virtual patients. This study aimed to investigate upper lip elevation (ULE) in AMS using 3D facial images.

Methods: A total of 212 Chinese participants with average dental and gingival display in AMS were enrolled and categorized into four groups: male adults (MAdu), female adults (FAdu), male adolescents (MA), and female adolescents (FA). Three-dimensional facial images were taken to measure upper lip length (ULL), philtrum length (PL), and upper vermilion height (UVH) at repose, and to measure upper lip length in AMS (ULL@AMS), ULE, and upper lip elevation ratio (ULER) in AMS. Cephalometric measurements were performed to assess maxillary incisor exposure (U1-Stms) and upper lip thickness (Sn-thickness, Ls-thickness, and Stms-thickness). Statistical analyses were conducted using analysis of variance and Pearson's chi-square tests.

Results: MAdu exhibited a significantly longer resting ULL (23.42 ± 2.23 mm) compared with FAdu (22.43 ± 1.83 mm), primarily due to their longer philtrum. ULL@AMS was 18.27 ± 2.20 mm in MAdu and 16.85 ± 2.36 mm in FAdu (P < 0.05); ULE was 5.15 ± 2.26 mm in MAdu and 5.58 ± 1.90 mm in FAdu (P > 0.05); ULER was 0.22 ± 0.09 in MAdu and 0.25 ± 0.08 in FAdu (P < 0.05). Both ULE and ULER were positively correlated with resting ULL and negatively correlated with Ls-thickness.

Conclusions: ULL, ULL@AMS and ULE in AMS were precisely measured using 3D imaging across different sex and age groups, offering preliminary normative references for related orthodontic treatment and esthetic procedures.

Objective: This study aimed to compare extraction versus orthodontic eruption decisions for impacted maxillary canines made by three artificial intelligence-based chatbots (ChatGPT, Gemini, and Grok) with those made by orthodontist raters, and to evaluate the overall accuracy of these artificial intelligence-generated recommendations.

Methods: Thirty-three patients with impacted maxillary canines were selected, and standardized case scenarios incorporating key diagnostic parameters were presented to the three chatbots. Their treatment decisions were recorded and compared with orthodontists' consensus decisions. Additionally, 10 general queries regarding impacted maxillary canines were submitted to the chatbots. The responses were rated by three orthodontists using a modified 5-point Global Quality Score.

Results: The chatbots and orthodontists showed moderate agreement regarding treatment decisions (κ = 0.411-0.524, P < 0.05). Gemini produced significantly more discordant responses, frequently over-recommending orthodontic eruptions (P = 0.002), whereas Grok and ChatGPT received significantly higher scores than Gemini in the case-based scenarios (P < 0.001). Grok outperformed both ChatGPT and Gemini for general queries (P = 0.006).

Conclusions: While Gemini showed lower clinical alignment with orthodontists for treatment decisions regarding impacted canines, ChatGPT and Grok demonstrated moderate agreement with orthodontists and produced relatively accurate responses. These findings highlight the potential of chatbots as supportive tools for orthodontic decision-making. However, their use requires careful supervision to avoid the risks associated with inaccurate or misleading recommendations.

Objective: Force application during orthodontic tooth movement (OTM) promotes oxygen depletion and bone remodeling. Deficiency of hypoxia inducible factor-1α (HIF1α) in myeloid cells accelerates OTM. Low-oxygen and high-salt conditions can stabilize HIF1α in myeloid cells. This study aimed to determine whether myeloid HIF1α levels influence OTM under low- and high-salt diets in mice.

Methods: Mice with and without HIF1α expression in myeloid cells received a low-salt (< 0.03% NaCl, tap water) or an high-salt (4% NaCl, saline) diet for two weeks. One week after the start of the diet, an elastic band was inserted between the first and second molars. The expression of inflammatory and bone remodeling genes, bone density, and extent of OTM were determined.

Results: Myeloid Hif1α expression did not modify high-salt-induced expression of the inflammatory genes interleukin-1β and interleukin-6. Myeloid-derived Hif1α and dietary salt levels did not significantly modify osteoblast responses to OTM. High-salt conditions and myeloid Hif1α deletion increased osteoclast numbers and expression of osteoclast-specific genes. This was paralleled by reduced bone density, which ultimately led to increased OTM.

Conclusions: A high-salt diet and the absence of HIF1α both lead to increased OTM. In the tested OTM model, exposure to high-salt conditions was largely independent of myeloid cell-derived HIF1α.

Objective: To compare the cytotoxicity of three dimensional (3D)-printed resins and conventional materials used for orthodontic aligner production.

Methods: 3D-printed materials such as 3Dresyn OD-Clear, Clear A, and Tera Harz TC-85 were compared with one thermoplastic material-Duran+. The samples were stored in artificial saliva at 37°C for 7 and 14 days to simulate the oral conditions during one phase of aligner therapy. The saliva was subsequently diluted with cell culture medium to concentrations of 10% (c1), 20% (c2), and 30% (c3). The cytotoxicity of the materials was assessed in human oral fibroblasts using the CCK-8 assay after incubation periods of 4 hours, 24 hours, 48 hours, and 72 hours.

Results: Cytotoxic effects were observed for Clear A (62.9% cell viability at c3; 7 days in saliva; 72-hour incubation) and Tera Harz (69.2% cell viability at c3; 14 days in saliva; 72-hour incubation). Significant differences under certain conditions were found between the following material pairs: Clear A and Tera Harz, Clear A and Duran+, 3Dresyn and Clear A, and 3Dresyn and Duran+ (P < 0.05). There were significant differences between the c1 and c3 for specific materials and incubation times (P < 0.05). No significant difference was found between the 7-day and 14-day aligner-wearing protocols (P > 0.05).

Conclusions: Among the tested materials, 3Dresyn OD-Clear and Duran+ demonstrated consistently good biocompatibility, highlighting their potential for safe clinical use. Although the other materials were generally biocompatible, they exhibited cytotoxic effects under certain conditions, underscoring the need for thorough testing to ensure safe clinical use.

Objective: To compare the effectiveness of 3- and 6-weekly orthodontic activation protocols on the alignment of crowded lower anterior teeth.

Methods: This randomized clinical trial involved 63 participants (29 males and 34 females) aged 16-30 years who had Little's Irregularity Index (LII) values of ≥ 5 to ≤ 11 mm and required treatment with a straight-wire appliance (SWA) with extraction of the lower first premolars. The patients were randomly allocated to 3- and 6-weekly activation groups and treated with a metallic SWA (0.022 × 0.028 slot size) and heat-activated nickel-titanium archwires of 0.014 to 0.020 inch diameter by a blinded orthodontist. The LII was measured using stone models, and the pain associated with orthodontic activation was assessed using a visual analog scale. Measurements were recorded at 0, 6, 12, 18, and 24 weeks after commencement of treatment. Root resorption in the lower anterior teeth was assessed using pre- and post-treatment small-field-of-view cone-beam computed tomography scans.

Results: The mean pretreatment LII was comparable between the 3- and 6-weekly activation groups (P = 0.865). However, at all subsequent visits, the 3-weekly activation group showed significantly lower LII values (P < 0.05). During the first six weeks, relief from crowding was greater in the 3-weekly activation group (P = 0.036). However, by the 12th week, the correction in LII was comparable between the two groups (P > 0.05). Mean pain score and root resorption showed no significant differences between the two groups.

Conclusions: The 3-weekly activation group showed greater and more rapid relief in mandibular anterior crowding than the 6-weekly activation group without causing more discomfort or root resorption.