Progress in Orthodontics最新文献

Background: This study aimed to analyze the effects of maxillary molar distalization using clear aligners with different intramaxillary and intermaxillary traction via the three-dimensional (3D) finite element method.

Methods: A 3D finite element model consisting of the maxilla, mandible, dentitions, periodontal ligaments (PDLs), attachments, and clear aligners was constructed. Five groups were established based on different traction modalities: group 1 (control group); group 2 (orthodontic mini-implants (OMIs) were implanted between the maxillary first molars and the second premolars on the buccal side); group 3 (OMIs were implanted in the infrazygomatic crest area between the maxillary first and second molars on the buccal side); group 4 (OMIs were implanted between the maxillary first molars and the second premolars on the palatal side); and group 5 (class II elastics were utilized between the maxillary canines and the mandibular first molars). OMIs were implanted 4 mm away from the alveolar crest in each experimental group. A force of 1.5 N was applied to each experimental group. The 3D displacement of the target teeth and stress distribution around the PDLs were analyzed.

Results: Group 4 exhibited the least amount of torque change in the upper anterior teeth and the highest displacement of the maxillary second molars. Group 3 showed smaller changes in anterior teeth torque and higher molar distalization efficiency compared to group 2. Group 5 showed adverse effects such as anterior teeth extrusion and mandibular anchorage loss.

Conclusion: OMIs implanted on the palatal side have advantages in preserving anterior teeth anchorage and improving the efficiency of molar distalization compared to those positioned on the buccal side. OMIs implanted in the infrazygomatic crest area between the first and second molars on the buccal side demonstrate benefits in the aforementioned aspects when compared to OMIs implanted between the first molars and the second premolars on the buccal side.

Background: Molar distalization with clear aligners (CAs) is a common treatment. However, when the molars reach their target position and the distal movement of premolars begins, the mesial movement of molars might reduce the overall efficiency of molar distalization. This study aimed to investigate tooth movement patterns under different CA designs in the premolar distalization stage using a four-dimensional mechanical simulation method.

Methods: A finite element method (FEM) model encompassing the maxillary dentition, periodontal ligaments, attachments, and associated CAs was constructed. The simulation aimed to replicate a premolar distalization of 2 mm within 10 sequential steps. Buccal interradicular mini-implants were used. Three groups of CAs were designed: the conventional CA design group (Con group), the second molar half-wrap group (SMHW group) and the all-molar half-wrap group (MHW group). An iterative computational approach was employed to simulate prolonged tooth movement resulting from orthodontic forces. Additionally, morphological alterations in the CA throughout the staging process were simulated utilizing the thermal expansion method.

Results: Compared with the Con and SMHW groups, the MHW group presented significantly reduced mesial movement of the first and second molars. However, the MHW group presented the greatest displacement of canines and incisors. The distalization efficiency of premolars in the MHW group reached 95.5-96.5%, which was substantially greater than that in the Con group (84.5-85%) and the SMHW group (75-75.5%).

Conclusions: The four-dimensional mechanical simulation results indicate that during the process of premolar distalization with CA, removing the distal portion of the aligner covering the first and second molars (MHW group) can effectively reduce the mesial movement of molars. Consequently, this approach can increase the overall efficiency of molar distalization.

Background: This study aimed to evaluate the effect of systemically administered anti-sclerostin antibodies (Anti-Scl Ab) on orthodontic tooth movements (OTM) in an ovariectomized rat.

Methods: Twenty-four 12-week-old female Sprague-Dawley rats were randomly divided into two groups: (1) ovariectomy (OVX) group, (2) ovariectomy + romosozumab (ROMO) group. OTM was performed 8 weeks after OVX. The ROMO group received subcutaneous injections of romosozumab twice a week, starting two weeks after OVX. Eight weeks after the OVX, an orthodontic force of 50 g was measured and applied by connecting orthodontic elastic bands between the maxillary first molar and a mini-screw to facilitate tooth movement (orthodontic treatment). Subsequently, the three rats were sacrificed on days 5, 7, 10, and 14. The plaster models were scanned to measure the amount of tooth movement. The effects on alveolar bone and periodontal tissues were evaluated through micro-computed tomography (micro-CT) analysis, tartrate-resistant acid phosphatase (TRAP) staining, and immunohistochemistry (IHC) analysis.

Results: The ROMO group showed more tooth movement on day 7 of orthodontic treatment. Conversely, on days 10 and 14, relatively less movement was observed. Analysis of the root furcation area of the maxillary first molars revealed that from the 7th day, BV/TV, Tb.N., Tb.Th. increased, while Tb.Sp. decreased in the ROMO group. More TRAP-positive cells were observed in the compression side of the OVX group, the ROMO group exhibited a marked decrease in the positive expression of the RANKL, OPG, and sclerostin. The OPG/RANKL ratio showed significant differences in expression between the two groups. The ROMO group exhibited a higher OPG/RANKL ratio than the OVX group, and the tension side exhibited a higher OPG/RANKL ratio demonstrating significant differences.

Conclusion: Romosozumab initially accelerated tooth movements, but later decreased tooth movement. As new alveolar bone is formed, the micro-CT parameters are also improved. Osteoclasts, RANKL, OPG, and sclerostin decreased, while the OPG/RANKL ratio became higher.

Introduction: Although with increasing popularity due to aesthetic appeal and comfort, clear aligners (CAs) are facing challenges in efficacy and predictability. Advancement in the underlying biomechanical field is crucial to addressing these challenges. This paper endeavors to provide a comprehensive framework for understanding the biomechanics of CA and enlightening biomechanics-based improvements on treatment strategies.

Methods: A thorough review of the English-language literature accessible through PubMed and Google Scholar, without any publication year restrictions, was undertaken to unravel the biomechanical aspects of CA.

Results: This review presented an up-to-date understanding of aligner biomechanics arranged by the framework of the material-dependent mechanical characteristics of CA, the geometric characteristics-dependent force transmission of the CA system, methods for studying the biomechanics of CA, and the biomechanical analyses for different types of tooth movement.

Conclusions: Biomechanics should be the fundamental concern for concepts, methods and adjuncts attempting to enhance the accuracy and predictability of tooth movement induced by CA. Improvement on material properties and alteration of geometric design of CA are two main approaches to develop biomechanically optimized force system. Exploration of real-world force sensing and monitoring system would make substantial progresses in aligner biomechanics.

Objective: This study compared the achieved tooth movement to that predicted in the preliminary simulated digital treatment plan between adults and teenagers.

Materials and methods: Records of 60 patients (30 adults; mean age: 36.6 ± 11.36 years, and 30 teenagers; mean age: 16.23 ± 2.25 years) were randomly selected. Initial and predicted models were obtained from the initial simulated treatment plan. The first model of the refinement scan was labeled as achieved. SlicerCMF software (version 3.1; https://www.slicer.org ) was used to superimpose the achieved and predicted digital models over the initial ones with regional superimposition on relatively stable first molars. 600 teeth were measured in each group for horizontal, vertical, angular movements, and transverse dimensions. Accuracy was defined as the achieved amount of movement minus predicted and was calculated for each individual and compared between teens and adults.

Results: The mandibular inter-canine width accuracy was statistically significant between groups (p = 0.050). Significant under-correction in horizontal movements was noted for mandibular first premolars in teenagers compared to adults (p = 0.037). There was considerable over-correction in horizontal movements for mandibular central and lateral incisors between groups (p < 0.05). No significant difference was observed between groups in the vertical plane. Rotations were underachieved for maxillary first premolars, more in adults than teenagers (p = 0.017).

Conclusion: The accuracy of achieved versus predicted tooth movement between adults and teenagers was significant for the inter-canine width. Mandibular central and lateral incisors showed significantly greater over-correction in adults in the horizontal plane. The accuracy of rotations and vertical movements was comparable.

Background: Obstructive sleep apnea (OSA) is a complex disorder characterized by interruptions in breathing during sleep, leading to a range of adverse outcomes from reduced quality of life to serious health risks, including cardiovascular diseases and increased mortality.

Main body: This manuscript reviews the orthodontists' essential role in the multidisciplinary healthcare team tasked with managing OSA. It particularly highlights critical orthodontic interventions, such as surgical-orthodontic maxillomandibular advancement (MMA), mandibular advancement appliances (MAAs), and rapid maxillary expansion (RME). These interventions are pivotal in modifying craniofacial structures to enhance airway patency. The importance of conducting a thorough airway analysis is underscored, assessing the complete anatomical and functional factors contributing to airway obstruction.

Conclusion: The paper calls for increased collaborative research efforts to develop standardized, evidence-based orthodontic procedures for effectively managing OSA, aiming to improve patient outcomes through specialized, tailored interventions.

Background: The purpose of the study was to measure the degree of conversion (DC) of direct-printed aligners (DPA) that were post-cured under ambient and nitrogen atmosphere at specific time intervals and investigate the kinetics of polymerization reaction of this material.

Methods: A total of 48 aligners were produced in 4 printing series by a 3D printer with TC-85DAC resin (Graphy Inc). From each series of printing, 12 aligners were included. The aligners were divided into two groups according to their post-curing conditions. One group was post-cured under ambient air with the presence of oxygen and the other under a nitrogen atmosphere, both using the same UV post-curing unit recommended by the company. The aligners were post-cured at six different time intervals: 1, 2, 3, 5, 10, and 20 min. Each time interval included 8 aligners, with 2 aligners from each series. The DC of the cured aligners was measured by means of attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) through acquisition of the respective spectra for each UV-curing condition. Statistical analysis was performed to compare the results and differences within each atmosphere post-curing protocol, as well as between the different selected atmosphere conditions. Statistical significance level was set at p-value ≤ 0.05.

Results: Pairwise analysis between post-curing protocols showed statistically significant differences only at the first minute of polymerization. Post-curing with nitrogen did not yield statistically significant results across different time intervals. Post-curing in ambient air showed some significant differences on the 1st and 2nd minute of the post-curing process.

Conclusions: Almost complete double bond conversion was observed. Significant differences were observed only during the first minute of polymerization under the nitrogen atmosphere.

Background: The aim of this study was to compare and evaluate three AI-assisted cephalometric analysis platforms-CephX, WeDoCeph, and WebCeph-with the traditional digital tracing method using NemoCeph software.

Material and method: A total of 1500 lateral cephalometric films that met the inclusion criteria were classified as Class I, Class II, and Class III. Subsequently, 40 patients were randomly selected from each class. These selected films were uploaded to 3 AI-assisted cephalometric analysis platforms and analyzed without any manual intervention. The same films were also analyzed by an orthodontist using the NemoCeph program.

Results: The results revealed significant differences in key angular measurements (ANB, FMA, IMPA, and NLA) across Class I, II, and III patients when comparing the four cephalometric analysis methods (WebCeph, WeDoCeph, CephX, and NemoCeph). Notably, ANB (p < 0.05), FMA (p < 0.001), IMPA (p < 0.001), and NLA (p < 0.001) varied significantly. Linear measurements also differed, with significant differences in U1-NA (p = 0.002) and Co-A (p = 0.002) in certain classes. Repeated measurement analysis revealed variation in SNA (p = 0.011) and FMA (p = 0.030), particularly in the Class II NemoCeph group, suggesting method-dependent variability.

Conclusion: AI-assisted cephalometric analysis platforms such as WebCeph, WeDoCeph, and CephX give rise to notable variation in accuracy and reliability compared to traditional manual digital tracing, specifically in terms of angular and linear measurements. These results emphasize the importance of meticulous selection and assessment of analysis methods in orthodontic diagnostics and treatment planning.

Background and aim: Some studies suggested an association between Temporomandibular Disorders (TMD) and psychosocial status, but most of them are focused on samples of patients looking for treatment or present limits of sample representativeness. The aim of the present study was to evaluate the psychosocial status in a large sample of adult population, further than to assess its association to TMD symptoms, oral behaviours, and self-reported facial trauma.

Results: the study sample included 4299 subjects older than 18 years randomly recruited from general population in public spaces during their daily life (1700 Males, 2599 Females mean ± SD age = 40.4 ± 18.1). Psychosocial status and pain-related disability were assessed by means of Patient Health Questionnaire 4 (PHQ-4) and Graded Chronic Pain Scale (GCPS). TMD symptoms were assessed by RDC/TMD and validated screening tools for TMD pain. Oral Behaviours Checklist was used to investigate on oral behaviours. Logistic regression model was used to evaluate the association of the psychosocial status, TMD symptoms, trauma, and oral behaviours. The association was tested using both univariate and multivariate models. The PHQ4 evaluation showed a severe impairment in 4.6% of our sample, moderate in 18.8% and mild in 32.5%. We found a Characteristic Pain Intensity (CPI) level and Interference Score greater that 30 respectively in 36.2% and 22.2% of the study sample. The GCPS status revealed a high disability with severe limitation in 2.5% of the sample, high disability with moderate limitation in 7.0%, low disability high pain intensity in 7.4% and low disability low pain intensity in 37.8%. Anxiety and depression's levels were significantly associated with gender, TMD pain, coexistence of TMD Pain and sound, and oral behaviours. GCPS status was significantly associated with age, TMD Pain, coexistence of TMD pain and sound, trauma, and oral behaviours.

Conclusions: In the general population, psychosocial impairment is associated to TMD pain, female gender, and report of oral behaviours. Hence, in adults with TMD accompanied by pain, psychosocial status should also be evaluated.

Background: The prevailing paradigm posits orthodontic tooth movement (OTM) as primarily a localized inflammatory process. In this study, we endeavor to elucidate the potential ramifications of mechanical force on systemic immunity, employing a time-dependent approach.

Materials and methods: A previously described mouse orthodontic model was used. Ni-Ti. springs were set to move the upper 1st-molar in C57BL/6 mice and the amount of OTM was. measured by µCT. Mice were allocated randomly into four experimental groups, each. corresponding to clinical phases of OTM, relative to force application. Terminal blood. samples were collected and a comprehensive blood count test for 7 cell types as well as. proteome profiling of 111 pivotal cytokines and chemokines were conducted. Two controls. groups were included: one comprised non-treated mice and the other mice with inactivated springs.

Results: Serum immuno-profiling unveiled alterations in cellular immunity, manifesting as. changes in percentages of leukocytes, monocytes, macrophages, neutrophils, and. lymphocytes, alongside key signaling factors in comparison to both control groups. The systemic cellular and molecular alterations triggered by OTM mirrored the dynamics previously described in the local immune response.

Conclusions: Although the exact interplay between local and systemic immune responses to orthodontic forces require further elucidation, our findings demonstrate a tangible link between the two. Future investigations should aim to correlate these results with human subjects, and strive to delve deeper into the specific mechanisms by which mechanical force modulates the systemic immune response.