Progress in Orthodontics最新文献

Background: The application of deep learning techniques in cephalometric analysis has become increasingly prominent. Although automatic landmarking models for cephalometric analysis have been developed, their accuracy still requires validation and relies heavily on clinicians to resolve discrepancies between results. To address these limitations, automatic diagnostic models have gained attention. However, there is no direct evidence establishing the superiority of one model over the other, especially the generalization and transferability.

Methods: Based on the same northern Chinese population external test dataset data and the data of the IEEE (Institute of Electrical and Electronics Engineers) 2015 ISBI (International Symposium on Biomedical Imaging) Grand Challenge dataset, we compared the performance, generalization ability, and transfer ability of the proposed two models, respectively.

Results: Our findings suggest that the automatic landmarking model outperforms the automatic diagnostic model in both external test dataset, with an accuracy of 90.80% on the IEEE dataset.

Conclusions: In this study, the comparison was indirect, with each model having its strengths: the automatic landmarking model offers precise measurements, while the automatic diagnostic model provides quicker results. The choice between them depends on clinical needs, and future work should explore hybrid models to combine the advantages of both.

This narrative review critically summarizes that microplastics and nanoplastics have been found in many different environments, including water and food, raising concerns on their possible harm to human health. Previous research indicates that microplastics may cause inflammation and tissue damage; however, the full extent of their health risks remains uncertain. Given the long-term use of plastic-based orthodontic appliances such as aligners, retainers, and widespread usage of adhesives, the potential release of microplastics and nanoplastics during routine wear and mechanical stress warrants thorough investigation to ensure patient safety and long-term biocompatibility. The literature search conducted for this review was structured but non-systematic, with no formal risk-of-bias evaluation. This review aimed to critically evaluate the impact of microplastics and nanoplastics on human health, with a focus on their relevance to orthodontics. The review also aimed to identify possible gaps in current research, particularly regarding the quantification of microplastic leakage from orthodontic appliances and their possible long-term effects. Current evidence highlights a clear need for more targeted research to inform and improve safety standards regarding microplastics and plastic usage in orthodontic and dental practice.

Background: Orthodontic tooth movement (OTM) is a complex biological process triggered by orthodontic forces (OF). This study aims to study the influence of sex and age on the gene expression of the dental pulp (DP) and periodontal ligament (PDL) of human premolars subjected to 7 and 28 days of OF in vivo.

Methodology: Linear mixed and negative-binomial models were used on previously published RNA sequencing (RNA-seq) datasets of DP and PDL tissue subjected to OF for 7 days and 28 days to verify if the effect of OF depends on sex and age. Differentially expressed genes (DEGs) were identified using false discovery rate and functional analysis was performed.

Results: The datasets consisted of 69 DP and 63 PDL samples from 46 and 41 patients respectively, with similar sex and age distribution. RNA-seq showed that sex did not influence the DP's gene expression profile, since only one DEG related to immune response was detected after 28-days of OF. In contrast, sex significantly affected PDL: 505 DEGs were found after 7 days of OF, related to bone homeostasis, osteoclastic activity and immune response. Age impacted both tissues; in DP, 18 DEGs related to Ca²⁺ regulation and DNA damage repair were found at 7 days, and 10 DEGs associated with repair and adaptive capacities emerged at 28 days. In PDL, 181 genes related to bone regeneration were identified at 28 days, with no DEGs noted at 7 days.

Conclusion: Our study demonstrates that under OF, DP's reaction is not sex-based, whereas PDL's is, particularly in the early phase of OTM, with women showing a more pronounced osteoclastic response. Age-related effects in DP tissue primarily influence Ca²⁺ homeostasis and DNA damage repair in early phases, and tissue repair and adaptive responses later. In contrast, age impacts PDL tissue mainly in the later stages of OTM, affecting its regenerative capacity.

Background: Clear aligner therapy has become increasingly prevalent in orthodontics, with composite attachments serving as critical components for achieving predictable tooth movements. Despite their importance, composite material selection remains largely empirical. This double-blind in vitro study assessed four composite materials' performance as aligner attachments under simulated clinical conditions.

Methods: Ninety-six extracted human teeth were arranged in upper and lower arch configurations. Four composite systems were evaluated: Omnichroma (79% filler), GC Aligner Connect (orthodontic-specific), G-Aenial Universal Injectable (69% filler, flowable), and Tetric Prime/Evoflow combination (dual-viscosity system). Each underwent aging simulation including 2308 thermal cycles (5-55 °C) and 840 insertion-removal procedures per 12-week period. Digital analysis assessed placement accuracy and volumetric changes at 12, 24, 48, and 96 weeks. Parameters evaluated included operation time, shear bond strength, placement accuracy, and wear resistance. All procedures were performed by a single calibrated operator following double-blind protocols. Polymerization utilized LED curing (1200 mW/cm², 430-480 nm), verified with radiometry.

Results: The Tetric combination required significantly longer placement time (31.08 ± 5.14 versus 5.22 ± 0.74 s for GC Aligner Connect, P < 0.001). Three-dimensional analysis revealed the Tetric combination demonstrated 81.24 ± 19.71% overflow versus 44.62 ± 19.91% for GC Aligner Connect (P < 0.001). After 96 weeks, G-aenial Universal Injectable showed significantly greater volume loss (27.40 ± 18.44%) compared to Omnichroma (18.29 ± 6.78%), GC Aligner Connect (17.56 ± 2.18%), and Tetric combination (14.22 ± 3.70%, all P < 0.001). Bond strength testing revealed no significant differences between groups (18.88-23.23 MPa, P = 0.121), with all materials exceeding clinical requirements.

Conclusions: Material viscosity and filler content substantially influence clinical performance during extended treatments. GC Aligner Connect demonstrated optimal balance of placement efficiency, dimensional accuracy, and durability for routine applications. High-viscosity composites showed superior long-term stability despite longer placement times. Injectable composites offered excellent efficiency but demonstrated accelerated wear after 48 weeks. These findings provide evidence-based guidance for material selection in clear aligner therapy, suggesting material choice should align with anticipated treatment duration and clinical requirements.

Background: To evaluate the effectiveness of a novel bioactive adhesive composite-comprising chitosan (CS), nanohydroxyapatite (nHA), β-tricalcium phosphate (β-TCP), and postbiotics-in enhancing the stability of orthodontic miniscrews immediately reinserted following failure in the same insertion site using a new miniscrew in an in vivo rat femur model.

Methodology: Composite adhesives were prepared in two distinct forms: foam and paste. Orthodontic miniscrews were placed into the left femurs of 28 male Sprague‒Dawley rats, and a small hole was drilled 15 mm distal to the miniscrew site. Orthodontic force was applied via a 100-gram Ni‒Ti closed coil spring attached between the miniscrew and the drilled hole. After 4 weeks, the rats were divided into four groups: Group 1 (4-week control), Group 2 (8-week control), Group 3 (paste adhesive), and Group 4 (foam adhesive). Group 1 rats were euthanized to assess primary miniscrew stability. Groups 2, 3, and 4 underwent a second surgery in which miniscrews were carefully removed and reinserted without adhesive, with paste-form adhesive, and with foam-form adhesive, respectively. After an additional 4 weeks, miniscrew stability was evaluated through histological analysis and mechanical pull-out testing. The data were analyzed via one-way ANOVA followed by Duncan's post hoc test. Normality was confirmed with the Shapiro‒Wilk test, and effect sizes (Eta Squared) were calculated due to the small sample size.

Results: Reinsertion without adhesive reduced the stability of miniscrews. However, when adhesive was used during reinsertion, the maximum force required to extract the miniscrew from the surrounding bone significantly increased, with the foam group demonstrating the highest pull-out strength (PS). Compared with the control group, the paste and foam groups presented greater mean bone‒implant contact (BIC) and bone volume (BV) values, although these differences were not statistically significant (p > 0.05). Effect size analysis revealed large differences in the clinical effects of BV and PS between the control groups and the adhesive-treated groups.

Conclusions: The bioactive adhesive composite can improve the primary stability of orthodontic miniscrews immediately reinserted into the same site after failure. The findings suggest that such adhesives may serve as a temporary adjunct to support anchorage continuity, warranting further in vivo evaluation before clinical application.

Objectives: To quantitatively compare the orthodontic forces exerted during mandibular incisor retraction by Perfitalign 4D aligners and thermoformed aligners over a 60-hour dynamic monitoring period, assess tooth movement trends, and investigate the effects of shape-memory properties on force characteristics.

Materials and methods: Three groups of aligners were designed for mandibular incisor retraction. Group A aligners were fabricated using Erkodur foils (ERKODENT Erich Kopp) via thermoforming, while Groups B and C were fabricated using DCA resin (LuxCreo) via 3D printing. Groups A and B possessed a step size of 0.15 mm, whereas group C had a step size of 0.20 mm. Force data were monitored on a mandibular model for 60 h using a multi-axis transducer at 4-hour wear intervals. Groups B and C underwent thermal reactivation after every 12 h of cumulative wear, with recordings taken immediately before and after each activation.

Results: All groups exhibited high repeatability (ICC > 0.9). Perfitalign 4D aligners exhibited significant force recovery after thermal reactivation, though the recovery degree slightly decreased with repeated activations. Vertical forces markedly fluctuated but increased after thermal reactivation. Intergroup comparisons revealed significantly lower lingual forces in groups B/C compared to group A (P < 0.05). For mesiodistal and vertical directions, forces in groups B/C showed no significant reductions compared to group A. Residual stress analysis revealed rapid initial decay in group A, which decelerated subsequently, while groups B and C exhibited cyclic characteristics of "decay-thermal reactivation-induced recovery-decay". At 0 h, moment-to-force ratios (Mx/Fy) for mandibular incisors were significantly lower in groups B/C (- 3.3 to - 8.7 mm) than in group A (- 8.0 to - 10.7 mm).

Conclusion: Perfitalign 4D aligners enable cyclic force recovery via shape-memory properties, independent of step size (0.15/0.20 mm). Despite larger steps, their lingual forces remained significantly lower than those of thermoformed aligners. A trend closer to bodily movement was observed with Perfitalign 4D aligners, although clinical studies are needed to validate movement efficiency and the long-term effects of elevated mesiodistal/vertical forces.

Aims: The aim of this retrospective cohort study is to calculate the accuracy of dental movement in consecutively treated patients treated with thermoformed and direct printed aligners.

Methodology: Two patient groups were included in the analysis. The first group consisted of 34 consecutively treated patients (23 females, 11 males; mean age 26.3 ± 13.7 years; age range 9-63), who were treated using 3D-printed aligners and a second group included 40 consecutively treated patients (28 females, 12 males; mean age 27.5 ± 12.5 years; age range 12-57), who received treatment with thermoformed aligners made of polyethylene terephthalate glycol (PETG). Digital analysis were performed to evaluate for every tooth torque, tip and rotational movements for each tooth as well as accuracy of planned movement. (Delta-Dent software, Outside Format, Milano, Italy) as well as accuracy of planned movement. The differences between groups in the toothwise movement accuracy were tested using the Mann-Whitney U test The Kruskall-Wallis test was used to evaluate the difference among teeth values. The differences were considered statistically significant at P < 0.05.

Results: 1018 teeth were measured. The overall accuracy of the torque was 60% for the DPA group and 66% for the TFA group; was 52% for the DPA group and 61% for the TFA group for the tip and the overall accuracy for rotations was 58% for the DPA group and 69% for the TFA group; none of the differences resulted statistically significant.

Conclusions: All treatments were successfully completed with similar amounts of refinement stages. No statistically significant differences were found between the two groups in respect of rotation, tip and torque movements.

Background: Disruption of iron homeostasis is closely associated with ferroptosis and inflammation-related diseases. Nuclear receptor coactivator 4 (NCOA4)-mediated ferritinophagy plays a central role in regulating intracellular iron levels and inducing ferroptosis. However, its involvement in orthodontically induced inflammatory root resorption (OIIRR) remains largely unexplored. METHODS : In vitro, a compressive force (CF) loading model was established using human periodontal ligament cells (hPDLCs). Western blotting and immunofluorescence staining were performed to detect the expression of ferroptosis-related proteins, including NCOA4, FTH1, and GPX4. Intracellular levels of malondialdehyde (MDA), Fe²⁺, and reactive oxygen species (ROS) were measured using a ferroptosis assay kit. JC-1 staining was used to evaluate mitochondrial membrane potential. NCOA4 was silenced via lentiviral transfection, and the small-molecule inhibitor 9a was used to further assess its functional role in ferroptosis. In vivo, an OIIRR mouse model was established. Hematoxylin and eosin (H&E) staining, tartrate-resistant acid phosphatase (TRAP) staining, and micro-computed tomography (micro-CT) were used to assess root resorption. The expression of NCOA4, FTH1, and GPX4 in periodontal tissues was evaluated via immunohistochemistry and immunofluorescence. Ferrostatin-1 (Fer-1), a ferroptosis inhibitor, was administered intraperitoneally to investigate its therapeutic effect on OIIRR.

Results: CF and IL-1β stimulation induced ferroptosis in hPDLCs, as indicated by increased intracellular Fe²⁺, ROS, and MDA levels, decreased GPX4 expression, and mitochondrial damage. NCOA4 expression was markedly upregulated in both in vitro and in vivo models, leading to ferritin degradation and iron overload. Fer-1 treatment effectively reduced oxidative stress and iron accumulation in vitro and alleviated OIIRR in vivo. Compound 9a suppressed NCOA4 expression and mitigated ferritinophagy-mediated ferroptosis.

Conclusions: NCOA4/FTH1-mediated ferritinophagy promotes ferroptosis under compressive and inflammatory conditions, contributing to OIIRR pathogenesis. Targeting the NCOA4/FTH1 axis may represent a promising therapeutic strategy for preventing orthodontically induced root resorption.

Background: Adolescents' lack of adherence to intra-oral removable appliances (IORAs) can lead to poor treatment outcomes. Available literature on this topic hasn't been comprehensively summarized. Existing reviews often combine data from various age groups, lack a standardized conceptual definition of adherence to IORAs, and offer limited evaluation of interventions aimed at improving adherence among adolescents. This scoping review aims to map the breadth and depth of the literature on adolescents' adherence to IORAs and identify research gaps for developing tailored interventions.

Methods: In accordance with Arksey and O'Malley's framework and PRISMA-ScR guidelines, a comprehensive search strategy was implemented across MEDLINE, CINAHL, Web of Science, and ProQuest Theses and Dissertations. Two researchers independently screened titles, abstracts, and full texts. A pilot-tested form facilitated data extraction. Risk of bias was evaluated using RoB 2, ROBINS-I, and JBI tools. Extracted data then underwent both descriptive and content analysis.

Results: The 14 included studies focused on adherence to wear-time recommendations (n = 13), with only one examining appointment adherence. Only seven studies (50%) were deemed high-quality. Adherence rates varied across IORAs: vacuum-formed retainers showed wear-time of less than 24 h/day, Hawley retainers averaged 12-15 h/day, Twin Blocks averaged 21 h/day, and Activators averaged 11.5 h/day. Studies pursued various aims: four explored patient perspectives and experiences; one assessed designed interventions; two evaluated treatment adherence and assessed adherence to both recommendations and appointments; and five identified associated factors. Several studies pursued multiple aims. Patient perspectives highlighted challenges like discomfort and social pressures, and enablers such as parental support. Limited intervention studies indicated potential benefits of digital and image-based monitoring. Adherence consistently fell short of recommended daily wear time (DWT), often influenced by motivation, parental involvement, and psychosocial factors.

Conclusion: Adherence among adolescents to the DWT for intraoral removable appliances is frequently suboptimal, displaying considerable variability depending on appliance type. Both individual and social determinants influence adherence. Robust study designs and a standardized conceptualization of adherence are imperative to generate high-quality, comparable evidence. Evidence-based interventions must be developed and tested to enhance adherence and ultimately optimize treatment outcomes within this patient population.