Korean Journal of Orthodontics最新文献

Objective: To measure and compare the extent of root resorption in the maxillary incisors following microimplant-assisted rapid palatal expansion (MARPE) and to identify risk factors of root resorption after expansion.

Methods: Cone-beam computed tomography images were obtained from a total of 60 patients both before expansion (T1) and 3 to 6 months after expansion (T2). Measurements taken included tooth length, root length, crown length and center of resistance. Resorption length (RL) and resorption length percentage (RLp), resorption volume (RV) and resorption volume percentage (RVp) and the amount of expansion were calculated.

Results: A significant difference in tooth length and volume was observed in both the central and lateral incisors before and after expansion. The resorption index (RL, RLp, RV, RVp) was significantly higher in the central incisors than in the lateral incisor. There was a significant correlation between several factors: age and RLp of the central incisors, the amount of expansion and RVp of the central incisors, tooth length of the central incisors and RL, RLp of the central incisors, root/crown ratio of the central incisors and RL of the central incisors, as well as tooth length of the lateral incisors and the RL of the lateral incisors.

Conclusions: Significant root resorption occurs in maxillary incisors following MARPE, with central incisors root resorption being significantly higher than lateral incisors. Key risk factors for root resorption after MARPE include advanced age, a larger amount of expansion, initial tooth length, and a root/crown ratio.

Objective: Miniscrew-assisted maxillary expansion devices are frequently used for patients with calcified midpalatal sutures. This study aimed to evaluate the effects of two bone-borne maxillary expansion appliances on the cranial and circummaxillary sutures by comparing cone-beam computed tomography (CBCT) images before and after transverse maxillary expansion.

Methods: A total of 81 patients (women = 58, men = 23) were treated with either a C-expander (n = 44) or an ATOZ expander (n = 37). CBCT images were obtained before (T0) and after (T1) maxillary expansion, and the widths of 10 circummaxillary sutures were measured in the sagittal, coronal, and axial planes. The Wilcoxon signed-rank test was used to compare the changes in suture width between the C-expander and ATOZ groups, and statistical significance was set at P < 0.05.

Results: The frontonasal, frontomaxillary, pterygomaxillary, nasomaxillary, internasal, intermaxillary, and midpalatal suture widths increased significantly after maxillary expansion in both the ATOZ and C-expander groups (both P < 0.05). The frontozygomatic, zygomaticomaxillary, and temporozygomatic suture widths decreased in the C-expander group (P < 0.05), whereas the frontozygomatic suture width increased significantly in the ATOZ group (P < 0.05). The width changes of the frontozygomatic, zygomaticomaxillary, temporozygomatic, pterygomaxillary, internasal, intermaxillary, and midpalatal sutures differed significantly between the two groups (P < 0.05).

Conclusions: Both the C- and ATOZ expanders affected the suture width in the naso-maxillo-zygomatic region. The C-expander decreased the circum-zygomatic suture widths, whereas the ATOZ expander widened the frontozygomatic suture with no effect on other circummaxillary sutures.

Objective: This meta-epidemiological study aimed to determine whether optimal sample size calculation was applied in orthodontic cluster randomized trials (CRTs).

Methods: Orthodontic randomized clinical trials with a cluster design, published between January 1, 2017 to December 31, 2023, in leading orthodontic journals were sourced. Study selection was undertaken by two independent authors. The study characteristics and variables required for sample size calculation were also extracted by the authors. The design effect for each trial was calculated using an intra-cluster correlation coefficient of 0.1 and the number of teeth in each cluster to recalculate the sample size. Descriptive statistics for the study characteristics, summary values for the design effect, and sample sizes were provided.

Results: One-hundred and five CRTs were deemed eligible for inclusion. Of these, 100 reported sample size calculation. Nine CRTs (9.0%) did not report any effect measures for the sample size calculation, and a few did not report any power assumptions or significance levels or thresholds. Regarding the specific variables for the cluster design, only one CRT reported a design effect and adjusted the sample size accordingly. Recalculations indicated that the sample size of orthodontic CRTs should be increased by a median of 50% to maintain the same statistical power and significance level.

Conclusions: Sample size calculations in orthodontic cluster trials were suboptimal. Greater awareness of the cluster design and variables is required to calculate the sample size adequately, to reduce the practice of underpowered studies.

Objective: This study aimed to investigate the effect of three-dimensional (3D) printed clear aligners (CA) with different designs on the extrusion of mandibular premolars using a force/moment measurement system and digital image correlation (DIC).

Methods: The forces and moments applied to the mandibular canines, first and second premolars were measured using a multi-axis force/moment transducer when an extrusion of 0.5 mm was planned, assuming the mandibular first premolars were intruded by 1 mm. In addition, displacement and strain changes in the CA were analyzed using the DIC method. CA designs were categorized based on the presence of first premolar attachment and subdivided into equigingival margins, 1-mm extended margins, equi-margins with 1-mm thickness and height, and equi-margins with 1-mm reduced buccolingual width. The CA was printed directly at a thickness of 0.5 mm, and the experiments were conducted at 37°C.

Results: The results showed that attachment played an important role in the extrusion of first premolars in both the force/moment measurement system and the DIC method. Intrusion was observed without attachment, even though extrusion was planned. CA designs apply greater force to the cervical region by extending the margin or reducing the buccolingual width, thereby improving extrusion efficiency.

Conclusions: Force and moment changes in direct 3D printed CA are complex and difficult to predict; however, modifying aligner designs, such as extending the margin or reducing buccolingual width, and using appropriate attachments could minimize unwanted tooth movement, optimize planned treatment, and increase treatment predictability.

Objective: This study aimed to compare the predicted and achieved labiolingual inclinations of the maxillary central incisors in adult Class II division 2 malocclusions treated with clear aligners using Power Ridges^® and composite attachments.

Methods: This retrospective study included 24 patients (mean age, 26.5 ± 3.3 years). The patients had Class II division 2 malocclusion and were treated with non-extraction with Invisalign^® clear aligners with either Power Ridges^® or composite attachments to enhance the predictability of required change in labiolingual inclination for the maxillary central incisors. Before treatment, treatment prediction and final digital models were exported as stereolithography files and superimposed using the eModel 9.0 "Compare" software. The predicted and achieved labiolingual incisor inclinations were compared.

Results: The mean accuracies of the achieved inclination of the central incisors were 68.3% in the Power Ridges^® group and 71.6% in the attachments group. No statistically significant differences in predictability were found between the groups (P > 0.05). A low positive correlation was observed between the predicted inclination change and the average absolute difference between the predicted and achieved inclinations (r = 0.19).

Conclusions: Predicted labiolingual inclination is not fully achieved with clear aligners in both the Power Ridges^® and attachment groups. Clinicians must take measures to counteract this limitation, specifically in Class II division 2 cases.

Objective: To assess and compare changes in the dimension and position of the mandibular condyle after tooth-borne (Hyrax) and tooth-bone-borne (Hybrid Hyrax) expansion.

Methods: Twenty-five patients who underwent expansion with either tooth-borne appliances (8 girls, 5 boys; mean age 14.3 ± 2.3 years) or tooth-bone-borne appliances (6 girls, 6 boys; mean age 13.8 ± 2.2 years) were examined. Condylar and glenoid fossa morphology before (T0) and 3 months after (T1) expansion were evaluated using cone-beam computed tomography. Condylar measurements (anterior, posterior, and superior joint spaces; condylar height, length, and width), along with sagittal and vertical skeletal and maxillary transversal measurements, were analyzed using Dolphin Imaging software. Wilcoxon and Paired t tests were used for T0 and T1 evaluations, and the Mann-Whitney U test for intergroup comparisons.

Results: At both T0 and T1, no statistically significant differences were observed between the groups in terms of condylar dimensions or the position of the condyle within the glenoid fossa. Maxillary transversal measurements increased after expansion in both groups (P < 0.01), with a significantly greater increase in first premolar width in the Hyrax group (P < 0.05). The vertical position of the posterior teeth showed no noteworthy changes (P > 0.05), except for the right second premolar. Temporomandibular joint measurements did not significantly change in either group after treatment (P > 0.05).

Conclusions: Neither tooth-borne nor tooth-bone-borne expansion caused significant changes in the condylar dimensions and position at the end of treatment.

Objective: To investigate which types of environmental exposure during pregnancy are risk and protective factors for cleft lip with or without cleft palate (CL/P).

Methods: This case-control study included 278 orthodontic patients with CL/P (CL/P group) and 51 without CL/P (non-CL/P group). Demographic and environmental exposure data were collected using questionnaires completed by the parents. Statistical analyses were performed to identify the potential risk and protective factors for CL/P.

Results: The two groups did not show significant difference in (1) body weight at birth and number of previous births; (2) fathers' ages at birth and occupation; (3) parents' chronic diseases, alcohol consumption, and exposure to harmful substances; and (4) mothers' smoking, secondhand smoking, and vitamin and calcium intake. Most patients with CL/P were born at normal term (≥ 37 weeks, 93.2%) with normal body weight (2.9-3.7 kg, 63.7%) and as either the first or second child (90.3%). In the CL/P group, the percentages of mothers who were very young or old (≤ 19 years, ≥ 40 years) and with physical labor in their occupation were low (1.8% and 2.2%, respectively). Compared with the non-CL/P group, the CL/P group showed a lower percentage of maternal folic acid intake (68.6% vs. 20.9%, odds ratio [OR] = 0.121; P < 0.001) and higher percentages of mothers' drug intake and fathers' smoking habits (3.9% vs. 16.2%, OR = 4.73, P < 0.05; 39.2% vs. 61.2%, OR = 2.44, P < 0.01).

Conclusions: The findings of this study may explain the association between environmental factors and CL/P risk.

Objective: External apical root resorption (EARR) is characterized by permanent loss of dental structure at the root apex. This study aimed to systematically review gene polymorphisms associated with EARR in orthodontic patients.

Methods: Electronic database searches were performed across several databases.

Results: This systematic review included 21 studies. Outcome measures were based on tooth dimensions observed on radiographs obtained before and after treatment. Polymorphisms in the following genes were genotyped using polymerase chain reaction-restriction fragment length polymorphism analysis: purinergic-receptor-P2X, ligand-gated ion channel 7 (P2RX7), caspase-1/interleukin-converting enzyme (CASP1/ICE), caspase-5 (CASP5), IL-1beta (IL1B), IL-1alpha (IL1A), interleukin-1 receptor antagonist gene (IL1RN), tissue non-specific alkaline phosphatase (TNSALP), tumor necrosis factor-alpha (TNFα), tumor necrosis factor receptor superfamily gene member 11a (TNFRSF11A), secreted phosphoprotein 1 (SPP1), tumor necrosis factor receptor superfamily gene member 11b (TNFRSF11B), interleukin 17A (IL17), interleukin 6 (IL6), receptor activator of nuclear factor-kappa B (RANK), osteoprotegerin (OPG), stromal antigen 2 (STAG2), vitamin D receptor (VDR), cytochrome P450 family 24 subfamily A member 1 (CYP24A1), cytochrome P450 family 27 subfamily B (CYP27B1), group-specific component (GC), and interleukin-1 receptor-associated kinases 1 (IRAK1).

Conclusions: Almost all studies suggested that IL1 gene is associated with EARR. Additionally, P2RX7 may be an important factor contributing to the etiopathogenesis of EARR. TNFRSF11A, SPP1, IL1RN, IL6, TNFRSF11B, STAG2, VDR, IRAK1, IL-17, CASP1/ICE and CASP5 have been identified in isolated studies. Further observational studies are needed to better explain the association between these genes and EARR.

Objective: To correlate temporomandibular joint (TMJ) morphology and position with cone-beam computed tomography (CBCT) images, Joint Vibration Analysis (JVA), and Jaw Tracker (JT) to develop a radiation-free, dynamic method for screening and monitoring the TMJ in orthodontic patients.

Methods: A total of 236 orthodontic patients without symptoms of TMJ disorders who had undergone CBCT were selected for the JVA and JT tests in this cross-sectional study. TMJ position and morphology were measured using a three-dimensional analysis software. JT measurements involved six opening-closing cycles, and JVA measurements were performed using a metronome to guide the mouth opening-closing movements of the patients. The correlations among the three measuring devices were evaluated.

Results: Abnormalities in condylar surface morphology affected the mandibular range of motion. The cut-off value results show that when various measurement groups are within a certain range, abnormalities may be observed in morphology (area under the curve, 0.81; P < 0.001). A 300/< 300 Hz ratio ≥ 0.09 suggested abnormal morphology (P < 0.05). Correlations were observed among the maximum opening velocity, maximum vertical opening position, and joint spaces in the JT measurements. Correlations were also observed between the > 300/< 300 Hz ratio, median frequency, total integral, integral < 300 Hz, and peak frequency with joint spaces in the JVA measurements.

Conclusions: JT and JVA may serve as rapid, non-invasive, and radiation-free dynamic diagnostic tools for monitoring and screening TMJ abnormalities before and during orthodontic treatment.