Progress in Orthodontics最新文献

Background: Synthetic polymers are widely used in medical and dental appliances, including clear aligners, retainers, splints, and sleep devices. Despite their widespread use, little is known about the release of microplastics from traditional thermoformed polymers compared with recently developed direct-printed photopolymers. Plastic particles have been detected in a variety of human tissues such as, lung, liver, spleen and kidneys. Each of these sites contain local resident macrophages tasked with maintaining homeostasis by clearing cell debris and foreign bodies. Like these organs, the oral cavity has an extensive population of macrophages that complete immune surveillance and support oral tissue health. Therefore, orthodontic plastic particles may have profound local and systemic biological impacts. As such, we systematically characterized release and particle structure of several clinical orthodontic polymers and visualized their uptake and impacts on macrophage differentiation.

Methods: Polymers were tested with the following compositions, direct-printed resins: ActiveMemory™ DCA (Lux Creo Inc.), Tera Harz TA-28 (Graphy Inc.), Nylon 12 (EOS) and thermoformed materials: Invisacryl™ (Great Lakes Dental Technologies), Zendura^® (Bay Materials), and Invisalign^® (Align Technology Inc.). Equal-sized disks were submerged in artificial saliva, incubated, and vortexed daily for one week. Particle release was quantified by flow cytometry and imaged by scanning and transmission electron microscopy. Uptake by macrophages was captured using live-cell timelapse microscopy, and macrophage differentiation was assessed by flow cytometry three days following microplastic co-cultures.

Results: All materials released detectable particles, with direct-printed polymers producing the highest concentrations. Direct-printed materials shed more micro-sized plastics, whereas thermoformed materials predominantly released nano-sized particles. Macrophages readily phagocytosed plastics about 2-10 μm in size. Co-culture with urethane-based direct-printed materials promoted macrophage differentiation toward M1-like iNOS⁺CD86⁺ subsets associated with pro-inflammatory activity.

Conclusions: Our findings reveal that commonly used orthodontic materials release micro- and nano-plastics that are readily taken up by macrophages, with direct-printed polymers releasing higher levels of immunostimulatory particles. The resulting shift toward pro-inflammatory macrophage phenotypes raises concern that material choice could influence not only local oral health but also systemic immune responses. These results underscore the importance of evaluating microplastic release in dental and medical devices to guide safer material selection and minimize unintended biological consequences.

Background: The aim of the study was to evaluate automated digital diagnostic setup in bimaxillary dentoalveolar protrusion cases using two software packages and to compare them to manual digital setup.

Methodology: Pre-treatment intraoral scans of 14 patients whose treatment plans involved extraction of four first premolars were imported as Standard Tessellation Language files into dentOne^® software (DIORCO co. ltd, Yongin, South Korea) and Ortho Simulation software (MEDIT Corp, Seoul, South Korea). Following tooth segmentation and selection of the teeth to be extracted, an automatic virtual setup was performed in each software. Moreover, manual virtual setups were performed by an orthodontist using dentOne^® software. Dental arch changes and dental movements and the duration taken to perform the setups were evaluated and compared using the appropriate statistical tests.

Results: The inter-canine, inter-premolar and inter-molar widths did not change significantly following manual virtual setup, while the arch length significantly decreased. The inter-premolar width, inter-molar width and arch length significantly decreased following both automated setups. The manual setup showed significantly greater lingual translation of maxillary and mandibular incisors compared to Ortho Simulation software (mean difference = 5.97 ± 1.10 mm and 7.02 ± 1.29 mm, respectively) and dentOne software (mean difference = 5.73 ± 0.96 mm and 6.95 ± 1.26 mm, respectively). The mesial translation of the maxillary and mandibular molars in Ortho simulation setup (8.35 ± 1.62 mm and 8.69 ± 1.91 mm, respectively) and dentOne setup (7.41 ± 1.28 mm and 7.74 ± 1.90 mm, respectively) was statistically significantly higher than that obtained using the manual setup (- 0.08 ± 0.27 mm, 0.03 ± 0.47 mm, respectively). All setups showed clinically significant lingual inclination of maxillary and mandibular incisors, with the manual setup exhibiting more lingual inclination than both automated setups. Ortho Simulation setup was the fastest method (4.14 ± 0.53 min), followed by dentOne automated setups (7.57 ± 0.94 min), then the manual setup (21.00 ± 1.66 min).

Conclusion: Despite being faster, the automated diagnostic setups for bimaxillary protrusion cases constricted the dental arch and did not manage the extraction spaces well, hence, simulating anchorage loss. These findings highlight the need for manual refinement of the automated setups.

Background: To explore the potential role of cGAS-STING/GPX4 axis-mediated ferroptosis in cementoblast mineralization under compressive force and to determine its involvement in orthodontically induced inflammatory external root resorption (OIIERR).

Methodology: An immortalized murine cementoblast cell line (OCCM-30) was subjected to a 2 g/cm² compressive force for 24 h to establish an in vitro loading model. Western blot was used to detect proteins associated with mineralization (RUNX2, OPN, OCN) and components of the cGAS-STING/GPX4 axis. Ferroptosis was assessed by measuring ROS, Fe²⁺, and MDA levels. Mitochondrial damage was examined via mitochondrial membrane potential analysis and mtDNA linkage evaluation. To further investigate the role of cGAS-STING/GPX4 axis-mediated ferroptosis, STING knockdown and Ferrostatin-1 (Fer-1) were employed. In vivo, an OIIERR mouse model was established, and the STING inhibitor H-151 was administered to assess the involvement of cGAS-STING/GPX4 axis-mediated ferroptosis in OIIERR.

Results: Compressive force significantly reduced RUNX2, OPN, OCN, and GPX4 expression, while increasing ROS, Fe²⁺, and MDA levels. Mitochondrial dysfunction, including decreased membrane potential and cytoplasmic mtDNA leakage, was observed. Western blot analysis showed that compressive force significantly upregulated cGAS, p-STING, p-TBK1 and p-IRF3 in OCCM-30 cells. Knockdown of STING or Fer-1 treatment restored mineralization under compressive force. In vivo, immunohistochemical staining confirmed the activation of cGAS-STING/GPX4 axis in the OIIERR group. Notably, administration of H-151 reduced the expression of pathway-related proteins and effectively mitigated root resorption.

Conclusions: Compressive force inhibits cementoblast mineralization by inducing ferroptosis via the cGAS-STING/GPX4 axis. Furthermore, H-151 effectively suppresses OIIERR in mice. Targeting cGAS-STING/GPX4 axis-mediated ferroptosis may serve as a potential therapeutic strategy for OIIERR treatment.

Background: This study aimed to evaluate the effect of external force applied from mini-screws to the aligner during space closure in extraction cases, and to determine the optimal loading conditions to prevent lingual crown tipping of the incisor and mesial tipping of the molar using the finite element (FE) method.

Methodology: A three-dimensional FE model of the maxillary dentition with extraction of first premolars was constructed, and three different loading conditions were designed. The aligner was activated for 0.25 mm of incisor retraction without using mini-screws, with application of 0, 100, 200, or 300 cN of distal force through mini-screws placed in the posterior region, or with application of 0, 100, 200, 300, or 400 cN of intrusive force through mini-screws placed in the anterior region, in addition to the application of 300 cN of distal force.

Results: As the magnitude of distal force increased, the degree of mesial tipping of the first molar gradually decreased, becoming almost zero with nearly 300 cN of distal force. As the magnitude of intrusive force increased in addition to the application of 300 cN of distal force, the degree of lingual crown tipping of the central incisor gradually decreased, becoming almost zero with nearly 400 cN of intrusive force.

Conclusion: Application of 300 cN of distal force to the aligner from mini-screws placed in the posterior region could completely prevent mesial tipping of the molar and anchorage loss during anterior retraction. Application of 400 cN of intrusive force from mini-screws placed in the anterior region could prevent lingual crown tipping of the incisor, thus providing better torque control for the incisors.

Background: This study evaluated the fit and thickness of aligners at tooth embrasures, comparing three-dimensional (3D)-printed and thermoformed aligners.

Materials and methods: Thirty aligners-3D-printed (no-offset and 0.05 mm offset) and thermoformed-were fabricated and mounted on a maxillary dental model. All aligners were scanned using microcomputed tomography. Embrasure gap distance and thickness were measured at coronal and cervical levels, and ratios reflecting aligner fit and thickness changes after fabrication were calculated. The Kruskal-Wallis and Mann-Whitney U tests were used for group and vertical level comparisons.

Results: The 0.05 mm offset 3D-printed aligners exhibited significantly smaller embrasure gaps than the no-offset 3D-printed and thermoformed aligners, with no significant differences between coronal and cervical levels. The other groups showed larger gaps at the cervical level. The embrasure fit ratio was higher in the 0.05 mm offset 3D-printed group (73-93%) compared with the no-offset 3D-printed group (58-86%) and thermoformed group (44-85%). Thermoformed aligners demonstrated significant thickness reduction after fabrication, with ratios of 36.5-88.5% relative to the original sheet, whereas 3D-printed aligners exhibited significant thickness increases, with ratios of 197-470% relative to the virtual design.

Conclusions: The 0.05 mm offset 3D-printed aligners exhibited a superior fit compared with the no-offset 3D-printed and thermoformed aligners. The 3D-printed aligners showed significant thickness increases at embrasures, in contrast to the notable thickness reductions observed in thermoformed aligners.

Background: Clear aligner therapy is gaining traction owing to its esthetics and comfort. Although most aligners use thermoforming, 3D printing offers advantages such as higher accuracy and reduced waste. While literature on the properties of some 3D-printed aligner materials compared to thermoformed ones is available, a comprehensive study is currently lacking that compares all three materials (iLuxclear (LC), Graphy Clear Aligner (GY), and RightBio Clear Aligner (RD)) with thermoformed materials, particularly regarding optical and biofilm adhesion characteristics.

Methodology: Three 3D direct-printed materials (LC, GY and RD) and two thermoformed materials (easyDu (ED) and Biolon (SC)) were tested. Surface morphology was analyzed by stereomicroscopy. Surface roughness (Ra) was measured at baseline (0 day) and after 45 days of immersion in artificial saliva. Light transmittance and color stability (ΔE₀₀) were evaluated after 7 and 14 days of aging in saliva, black tea, and coffee. Bacterial adhesion was quantified using Streptococcus mutans (S. mutans) at baseline and after 3 and 7 days.

Results: The 3D direct-printed aligners, particularly the LC group, exhibited increased surface morphology irregularities and significantly higher Ra values than the thermoformed materials; Ra increased after 45 days of immersion in artificial saliva across all groups. The thermoformed materials maintained stable color integrity, while the 3D-direct printed materials varied in performance. GY demonstrated a uniform surface structure, lower roughness, and the highest color stability, whereas LC and RD experienced significant discoloration. The RD group exhibited significantly higher S. mutans adhesion, whereas the thermoformed materials exhibited superior biofilm resistance. Notably, GY achieved comparable S. mutans adhesion to the thermoformed materials after a 7-day culture.

Conclusions: Among the 3D direct printed aligners, GY achieved comparable surface and microbiological performance to conventional options. These findings underscore their potential for balancing esthetics, susceptibility to bacterial adhesion, and clinical performance in clear aligner therapy.

Objective: This study examined the relationship between smile aesthetics perception and personality factors among individuals with varying dental education backgrounds.

Materials and methods: This cross-sectional study included 412 participants categorized into four groups: pre-clinical dental students, clinical dental students, practicing dentists, and laypeople. Participants rated 20 photographs depicting variations in maxillary midline diastema, central incisor crown length, smile arc, gingival display, and incisal plane cant on a ten-point attractiveness scale. Personality factors were assessed using the NEO-FFI questionnaire, measuring Neuroticism, Extraversion, Openness, Agreeableness, and Conscientiousness.

Results: Dental professionals assigned significantly lower aesthetic scores to smiles with a 2.0 mm central incisor crown reduction, a 4.0 mm gingival display increase, and an incisal plane cant compared to non-dental raters (P < .05). Higher Agreeableness and Conscientiousness scores were associated with a preference for smiles without midline diastema (r = .118, 0.112; P = .017, 0.023). Higher Extraversion and Openness scores were associated with a preference for no gingival display (r = .147, 0.123; P = .003, 0.012).

Conclusions: Perceptions of smile aesthetics varied significantly between dental and non-dental raters. Severity of smile discrepancy has a predictive role in aesthetic preferences, influencing the perceived attractiveness of specific smile characteristics. Personality factors had some associations with the perceived attractiveness of specific smile characteristics. Understanding how severity of smile discrepancy, personality traits and dental training influence esthetic preferences can help clinicians better tailor smile design and treatment communication to individual patient expectations.

Background: Miniscrew-assisted palatal expansion techniques such as MARPE (Miniscrew-Assisted Rapid Palatal Expansion) and MASPE (Miniscrew-Assisted Slow Palatal Expansion) represents non-surgical alternatives for the correction of transverse maxillary deficiencies in adults. However, concerns have arisen regarding their potential to cause craniofacial complications due to the high forces applied for midpalatal suture opening in skeletally mature patients.

Methodology: This article aims to present and describe isolated clinical cases of cranialfacial complications observed in adult patients following MARPE and MASPE procedures, and to discuss the potential biomechanical mechanisms behind these events. Eleven clinical cases involving adult patients who underwent skeletal midface expansion with miniscrew-assisted devices are presented. All cases exhibited craniofacial unwanted dislocations identified through CBCT imaging, including zygomatic fractures, parasutural bone fractures, and asymmetrical disjunction of craniofacial sutures. These events were retrospectively documented through clinical follow-up and radiographic analysis.

Results: Among the eleven cases presented, complications included seven asymmetric fractures of the frontonasal process, two orbital fractures, one zygomatic bone fracture, and one parasagittal fracture of the palatine bone. These complications were primarily observed in patients who underwent MARPE with rapid activation protocols. One minor complication occurred in a MASPE case, where the patient followed the prescribed slow activation schedule.

Conclusion: Non surgical mid facial expansion is a potential source of unwanted and unpredicted dislocations in the craneofacial complex. According to this report the observed complications do not seem to be age related and are difficult to predict from the CBCT. A close clinical follow up including force monitoring and force limitation should be mandatory when performing MARPE. MASPE and minimally invasive SARPE could be alternatives to minimise the incidence of creaniofacial complications.

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.