Progress in Orthodontics最新文献

Background: Mechanical stress triggers an increase in cellular reactive oxygen species (ROS), which is associated with the impairment of osteogenesis. During orthodontic treatment, bone marrow mesenchymal stem cells (BMSCs) experience mechanical stress, yet the oxidative profile and redox regulatory mechanisms under such stress, especially involving Nicotinamide adenine dinucleotide (NAD⁺), are not well understood, necessitating further research into their roles in orthodontic therapies.

Methods: The Tension System was established to detect ROS changes in BMSCs under cyclic stretch stress, with H₂O₂ simulating uncontrolled ROS. Flow cytometry and fluorescence staining measured ROS, while an NAD⁺/NADH assay kit assessed NAD⁺ levels. qRT-PCR and Western blotting analyzed expression of NAD⁺ synthesis and consume enzymes. Osteogenic potential was evaluated by qRT-PCR, Western blotting, and Alkaline phosphatase (ALP) staining. Loss-of-function and supplementation assays explored role of NAD⁺ in oxidative stress and Nrf2 regulation, with localization assessed by immunofluorescence and Western blotting. In vivo osteogenic effects were confirmed using an orthodontic tooth movement (OTM) model, with osteogenesis assessed by immunohistochemistry and microCT for OTM measurements.

Results: Cyclic stretch stress increased ROS in BMSCs over 24 h and boosted osteogenic differentiation. However, increased ROS from H₂O₂ hindered this process. Notably, NAD⁺ levels rose with cyclic stretch, and experiments showed it supported osteogenesis by controlling ROS level in BMSCs. Furthermore, NAD⁺ regulated BMSC ROS via Nrf2 nuclear translocation. Rat models indicated that NMN supplementation enhanced osteogenic and osteoclastic markers and accelerated tooth movement, while FK866 inhibited this effect.

Conclusions: We identified that NAD⁺/Nrf2 signaling regulated oxidative level and thus promoted osteogenic commitment of BMSCs under cyclic stretch stress. Targeting NAD⁺ metabolism or administrating exogenous supplementation to promote bone rebuilding could be a prospective therapy to accelerate OTM.

Background: Skeletal Class II malocclusion, often associated with mandibular deficiency, is commonly treated with functional appliances. Precision Wings are a functional appliance that provides an alternative approach by combining mandibular advancement with dental alignment.

Objective: This systematic review aimed to evaluate the effectiveness of Precision Wings in treating skeletal Class II malocclusion in growing patients.

Eligibility criteria: Studies assessing the correction of skeletal Class II malocclusion in growing patients treated with Precision Wings were selected according to the PICOS strategy. The PRISMA guidelines were followed.

Information sources: Unrestricted electronic searches were conducted across seven databases up to February 2025.

Risk of bias and synthesis of results: The ROBINS-I tool was used to assess the risk of bias (RoB) in non-randomized studies. A random-effects meta-analysis was performed, and the certainty of the evidence was evaluated using the GRADE approach.

Results: Seven studies were included, and data were extracted. Mean differences (MDs) with 95% confidence intervals (CIs) were calculated using random-effects meta-analysis. The findings suggest that Precision Wings may be effective in treating skeletal Class II malocclusion in growing patients through both dental and skeletal changes. Regarding skeletal effects, sagittal changes were limited to the mandible and were of small magnitude, with a reduction in ANB° (MD = -0.81; 95% CI: -1.04 to -0.58; p < 0.001) occurring exclusively due to an increase in SNB° (MD = 0.55; 95% CI: 0.11 to 0.98; p = 0.01), while no significant changes were observed in SNA° (MD = -0.02; 95% CI: -0.42 to 0.38; p = 0.91). The included studies did not report significant vertical effects. Meta-analyses comparing Precision Wings with other functional appliances were not feasible due to the small number of studies evaluating each comparison and the substantial clinical and methodological heterogeneity across the included studies.

Conclusion: Although the available scientific evidence on this topic is limited, treatment with Precision Wings appears to offer minimal clinical improvement in mandibular growth for the correction of skeletal Class II malocclusion. To obtain more conclusive findings, future research should prioritize well-structured randomized clinical trials with standardized treatment protocols, extended follow-ups, and consistent cephalometric assessment methods.

Objective: This study aimed to elucidate metabolic alterations in gingival crevicular fluid (GCF) during orthodontic tooth movement (OTM) and investigate the role of the succinate-SUCNR1 axis in bone resorption and tooth movement.

Results: OTM was accompanied by the change of TCA cycle and increase of succinate in the human GCF. Succinate accumulation was observed in periodontal ligament cells (PDLCs) under compressive force, accompanied by increase of glycolysis and decrease of succinic dehydrogenase activity. Suppression of the succinate-SUCNR1 axis reduced osteoclastogenesis in BMDMs. OTM slowed down in the SUCNR1^-/^- mice when compared with wild mice.

Conclusion: OTM is accompanied by the increase of succinate in periodontal tissues. Compressive force induces metabolic reprogramming in PDLCs, leading to enhanced succinate production. Succinate promotes macrophage migration and osteoclast differentiation via the SUCNR1 axis, ultimately facilitating orthodontic tooth movement. These findings provide a new potential therapeutic target for regulating periodontal tissue remodeling during orthodontic treatment.

Background: Observational studies indicate that obesity correlates with jaw development and remodeling; however, causality remains unclear. This study aimed to examine the potential causal relationship between life-course adiposity and jaw anomalies.

Methods: Utilizing summary statistics from genome-wide association studies predominantly of European ancestry, we conducted univariable and multivariable Mendelian randomization (MR) to estimate overall and independent effects of six obesity traits (birth weight, childhood body size, childhood body mass index [BMI], adult BMI, adult body fat percentage, and adult waist circumference) on seven jaw anomalies, including bimaxillary hypoplasia, prognathism, retrognathism, and jaw asymmetry. Comprehensive sensitivity analyses verified robustness, assessed heterogeneity, and examined pleiotropy.

Results: In univariate analyses, genetically predicted thinner childhood body size (inverse variance weighted [IVW] OR: 0.41, 95% CI: 0.27-0.62, p < 0.001), adult BMI (IVW OR: 0.65, 95% CI: 0.53-0.80, p < 0.001), and waist circumference (IVW OR: 0.60, 95% CI: 0.45-0.82, p = 0.001) were significantly associated with the risk of mandibular retrognathia following Bonferroni correction. Multivariable MR analysis revealed a direct causal effect of childhood body size on mandibular retrognathia, independent of birth weight, adult adiposity, growth hormones, and lifestyle factors. No evidence was found for causal associations between life-course adiposity and other jaw anomalies. Sensitivity analyses produced broadly consistent findings.

Conclusions: This MR study provides new evidence on the direct causal effects of thin childhood body size on the risk of mandibular retrognathia, emphasizing the critical role of early childhood nutrition and weight management in craniofacial development.

Objective: Molar sequential distalization with clear aligners was advantageous. However, the effect of periodontal status on it has yet to be investigated. This study aimed to analyze the influence of the different periodontal states on molar distalization to reduce the adverse mechanical stimulation caused by periodontal states by the different stagings of movement and further explore therapeutic recommendations for clinical practice.

Methods: To ascertain the initial displacement of dentition and periodontal ligament (PDL) hydrostatic stress, finite element models (FEMs) were developed. These models included the distalization of the second molars (Step A) and the first molar (Step B) in three distinct periodontal conditions (simulating the periodontal state of mild, moderate, and severe periodontitis) and three distinct distances (0.10 mm, 0.18 mm, 0.25 mm).

Results: Periodontal status affected the tooth movement during molar distalization. During the molar distalization with 0.25 mm step distance, the initial displacement of the molar was greater in the model with worse periodontal condition. However, it did not increase the efficiency of tooth movement because the initial displacement is accompanied by tipping. Moreover, the second molar relapse to mesialization for a reaction from the first molar distalization affected efficiency. Fortunately, reducing the step distance could control those undesired tooth movements positively associated with alveolar bone resorption.

Limitations: The finite element method cannot simulate complex periodontal conditions in clinical practice.

Conclusion: To reduce the undesired tipping and relapse, the personalized staging of movement should be designed according to the periodontal condition. Designing 0.18 mm step distance for patients with 1/3 alveolar bone resorption is recommended, whereas patients with 1/2 alveolar bone resorption need 0.1 mm. These recommendations can guide orthodontists in designing effective treatment plans for patients with varying degrees of periodontal disease.

Background: Early intervention in Class III malocclusion aims to prevent the need for surgery in adulthood by enhancing upper jaw growth while limiting lower jaw development. Although traditional facemask treatment remain common, bone-anchored devices are increasingly used, claiming better skeletal control and patient compliance. However, strong evidence supporting these advantages is limited.

Methods: Single-center, parallel-group, randomized controlled trial with 1:1 allocation ratio.

Participants:  28 growing Class III patients (mean age 9.7 ± 1.3 years) in mixed dentition with skeletal class III malocclusion.

Interventions:  Patients were randomly assigned to either hybrid hyrax with facemask (HH + FM, n = 14) or hybrid hyrax with mentoplate (HH + MP, n = 14). All received Alt-RAMEC protocol expansion. FM group used 360-400 g/side elastic traction 12-14 h daily; MP group used 185 g/side continuous traction.

Objective:  To compare 5-year three-dimensional (3D) skeletal effects between HH + FM and HH + MP protocols.

Outcome:  Primary outcome was 3D volumetric changes of upper and lower jaw at 1 year (T1) and 5 years (T2) post-treatment, measured using low-dose CT scans.

Randomization: 28 patients were allocated to either treatment-protocols using sequentially numbered opaque, sealed envelopes. The randomization sequence was generated with a 1:1 allocation ratio.

Blinding: Due to the nature of the trial, the operator and children could not be blinded to the treatment allocation. However, blinding was used when assessing the outcomes.

Results: Follow-up: one patient was lost at the one-year follow-up and an additional three patients were lost at the 5-year-follow-up.

Outcomes: At T2 (5 years), maxillary advancement was identical between both groups (0.85 mm ± 0.5). Mandibular growth control showed minimal difference (FM: - 0.01 mm ± 0.24; MP: 0.10 mm ± 0.33). No significant differences were found between groups for any skeletal measurements (p > 0.05). Male patients showed lager mandibular changes both signed (p < 0.03) and unsigned (p < 0.01).

Harms: minor harms were encountered with the anchor hooks (fracture or mucosal irritation), however none led to treatment cessation.

Conclusions: Both protocols demonstrated comparable long-term skeletal effects in Class III correction. Treatment choice should be based on individual patient factors rather than assumed mechanical advantages.

Background: The symbiotic relationship between the oral microbiome and the host immune system is a prerequisite of oral health. Disruptions to this system can be associated with the development of diseases like dental caries. Introducing orthodontic treatments, such as aligners and fixed appliances, might impact this microbial ecosystem. This study evaluated potential changes in salivary microbiome and the level of inflammatory marker myeloid-related protein 8/14 in patients undergoing orthodontic treatment with aligners or fixed appliances.

Methods: Forty-eight patients were divided into two groups for treatment with fixed appliances or clear aligners. Unstimulated saliva samples were collected at baseline, three, and six months for microbiome analysis via 16 S rRNA sequencing and MRP-8/14 level measurement using ELISA.

Results: Among 503 identified microbial species, no significant changes were noted in overall microbiome. A considerable increase of caries-relevant species could not be observed either. MRP-8/14 levels remained unchanged across treatments, indicating no alterations in the inflammatory level.

Conclusion: Orthodontic treatment with fixed or removable appliances does not significantly alter the salivary microbiome or influence inflammation, suggesting that these interventions are unlikely to affect oral health negatively.

Background: The mechanical properties of directly 3D-printed clear dental aligners are currently constrained by the limitations of available 3D printing materials. This study aimed to investigate the mechanical properties of direct 3D-printed clear resin embedded with orthodontic wire under different surface treatments to propose a novel integration method for orthodontic appliances and treatment.

Methods: The stainless-steel wires were divided into three groups based on surface treatments: control groups (C), sandblasting group (S), sandblasting and acid etching group (SA). Surface characteristics were analyzed and interfacial shear strength (IFSS) was measured. Dumbbell-shaped specimens were fabricated using 3D-printed clear resin and divided into four groups, depending on whether they were embedded with stainless-steel wires subjected to different surface treatments. The static and dynamic mechanical properties tests were carried out to calculate elastic modulus, tensile strength, and stress relaxation.

Results: The average roughness and surface morphology of stainless-steel wires exhibited significant differences (P < 0.001) following different surface treatments. Sandblasting and acid-etching significantly enhanced IFSS, resulting in a fivefold increase to 28.8 MPa. The elastic modulus and tensile strength of the 3D-printed resin embedded with wires were significantly higher than those of the pure 3D-printed resin group. However, no significant differences in elastic modulus were observed among the different wire surface treatment groups. The sandblasting and acid-etching group exhibited higher residual stress compared to the other groups during both 6-hour and cyclic stress relaxation tests.

Conclusion: This study presents a novel approach to 3D-printed clear dental aligners integrated with metal wires for orthodontic treatment. Surface treatment of orthodontic metal wire through sandblasting and acid etching enhances the bonding strength between the wire and 3D-printed clear resin, improving the static and dynamic mechanical properties of directly 3D-printed clear resin appliances. The innovative process and device provide an integrated solution for digital orthodontic treatments.

Introduction: Achieving a harmonious soft tissue profile and enhancing facial appearance are key goals of early treatment for skeletal class III malocclusion.

Aim: To summarize the current evidence regarding the effects of Class III orthodontic treatment on facial soft tissues, and to compare various Class III orthodontic appliances.

Methods: A comprehensive search was conducted up to July 2024, using seven databases, with no language restrictions. RCTs and controlled non-randomized studies were included in this systematic review. The GRADE framework was applied to evaluate the quality of evidence.

Results: Thirty studies were included in this review, of which sixteen were appropriate for quantitative synthesis. The age range fell between 6.6 and 12.3 years. The FM/RME protocol resulted in a 1.58 mm increase in upper lip protrusion and a 4.73-degree decrease in the nasolabial angle compared to the control group. Chincup treatment led to a 2.13 mm increase in upper lip protrusion and a 2.63 mm decrease in lower lip protrusion compared to the control group. The pooled estimate demonstrated a significant increase of 1.82 mm in upper lip protrusion, a significant retrusion of 3.14 mm in the lower lip, and a backward movement of the chin by 4.8 mm in patients treated with miniplate-anchored orthopaedic facemask (FM/MP) compared to the untreated group. However, no significant difference was found between FM/RME and FM/MP, except for a noticeable decrease in the nasolabial angle in the FM/RME group. The analysis of FM/Alt-RAMEC versus FM/RME did not reveal any difference in soft tissue outcomes, except for the upper lip protrusion. The Alt-RAMEC group showed a more pronounced anterior movement of the upper lip by 0.67 mm compared to the RME group. The quality of evidence supporting these findings ranged from low to moderate.

Conclusions: There is low to moderate evidence suggesting that early treatment positively influences the soft tissues in Class III patients. However, these conclusions are based on a two-dimensional analysis of cephalometric images, which may not provide complete or accurate information. Therefore, more RCTs using comprehensive 3D analysis are needed to confirm these results.

Registration: PROSPERO ( CRD42024517924 ).

Background: During the process of intruding the mandibular anterior teeth (MAT) with clear aligners (CA), the teeth are susceptible to undesigned buccal and lingual inclinations, leading to complications such as excessive alveolar bone resorption and root exposure that significantly compromise the treatment outcome. Therefore, it is imperative to investigate the underlying causes and develop effective coping strategies.

Methods: We first statistically analyzed the clinical issues, then used FEA to explore their underlying mechanisms to guide the design of attachments in clinical practice. Specifically, CBCT data before and after the intrusion treatment of MAT were collected to analyze the labial-lingual inclination of the MAT and the distance between the root apex and alveolar bone wall. Finite element analysis (FEA) models of MAT undergoing vertical intrusion with standard CA were created with eight incisor mandibular plane angles (IMPA) to assess displacement trends, labial and lingual moments, and crown contact forces. Additionally, six aligner attachments were designed to simulate and analyze their biomechanical mechanisms.

Results: Significant differences were observed in changes before and after treatment. When the IMPA was 90°, the crown experienced a labial moment. The labial root control ridge (RCR) increased the labial moment of the crown, while the lingual RCR and labial attachment (LA) increased the lingual moment. The lingual fossa excavating holes (LFEH) group also increased the labial moment. The lingual RCR enhanced the lingual movement of the crown, whereas the LFEH promoted labial movement. During the intrusion of MAT, a comprehensive design incorporating labial intrusive attachments, labial RCR, lingual RCR, and LFEH can be employed to ensure true vertical intrusion of the lower anterior teeth.

Conclusion: This study revealed the biomechanical changes during intrusion, and innovatively designed the LFEH, thereby promoting the development of novel orthodontic techniques and improving clinical treatment outcomes.