Search

Orthodontic treatments with Invisalign® require the use of attachments, which are composite resin buttons attached to tooth surfaces. Attachments constitute one of the most powerful tools for improving the efficiency of orthodontic tooth movement. The main purpose of this study was to evaluate surface wear over six months in two resin composites (Filtek Z350 XT, 3MESPE and Amelogen Plus TW, Ultradent Products Inc. ) used for making Invisalign® attachments. These composites were selected for their esthetic and mechanical properties. Forty attachments were bonded to the buccal surface of maxillary teeth. Materials were randomized and assigned in a double blind manner. Impressions were taken of the attachments using a preestablished technique immediately after bonding and following 6 months of clinical use. The impressions were examined by Scanning Electron Microscopy (SEM) at 12-fold magnification to identify changes in surface texture and attachment shape. Data were analyzed using Mann-Whitney's test on the overall ranking of detected changes in those variables. Statistically significant differences (P<0. 001) were found for surface wear, with greater changes in Amelogen Plus. Attachment shape did not change significantly in either material (P>0. 05). According to the results of this study, the alteration of the attachment surface during the first six months of treatment depends on the composite used, while attachment shape does not appear to be affected, so the clinical performance of the materials evaluated could be considered acceptable., (Sociedad Argentina de Investigación Odontológica.)

Objectives: To evaluate the clinical effectiveness of regenerative treatment of intrabony defects in combination with consecutive orthodontic therapy with clear aligners in stage IV (type 2) periodontitis. Method and materials: Ten patients with a total of 103 intrabony defects were analyzed after regenerative surgery using collagen-deproteinized bovine bone mineral with or without collagen membrane or enamel matrix derivative followed by orthodontic therapy with clear aligners. Changes in radiographic bone level and probing pocket depths were evaluated after 1 year (T1) and at final splinting (T2) after orthodontic tooth movement. Results: Mean radiographic bone level gain was significant, with 2.13 ± 1.64 mm at T1 and 3.02 ± 2.00 mm at T2. Mean probing pocket depth was significantly reduced from 5.40 ± 1.80 mm at baseline to 3.78 ± 1.73 mm at T1, and remained stable with 3.73 ± 1.70 mm at T2. Pocket closure (≤ 4 mm probing pocket depth) was accomplished in 76% of all defects. Tooth loss amounted to 2.9%. Conclusion: Within the limitations of the retrospective study design, the findings suggest that the interdisciplinary treatment of periodontitis stage IV by regenerative periodontal surgery and consecutive orthodontic therapy with clear aligners can lead to favorable results. [ABSTRACT FROM AUTHOR]

We aimed to explore the best orthodontic step distance of the right upper central incisor with mild, moderate, and severe pathological displacement achieved via a clear aligner. Three-dimensional models of maxilla-tooth-periodontal ligament clear aligner of the right upper central incisors with five different steps of 0.1, 0.125, 0.15, 0.165, 0.25 mm and three different alveolar bone heights were established via finite element analysis. We analysed the changing trends in initial displacement, the periodontal ligament, the alveolar bone, and apical stress of right upper central incisor. In the process of retraction, the right upper central incisor a movement trend of the crown deviating from the distal root to the mesial, and with the decrease of the height of the alveolar bone and the increase of the displacement, the crown would appear distal labial torsion with a deepening trend of vertical overlay.The maximum stress distribution of the periodontal ligament and alveolar bone showed a positive correlation. The overall stress distribution of the periodontal ligament and apical stress increased with decrease of alveolar bone height and the increase of alveolar bone displacement. In patients with mild, moderate, and severe pathological displacement of the right upper central incisor, the best step distance of anterior tooth retraction is 0.165, 0.15, and 0.125 mm, respectively. [ABSTRACT FROM AUTHOR]

Orthodontic re-treatment may be required in cases of sub-optimal treatment outcomes. These outcomes may often be due to appliance-driven treatment plan, inadequate bio-mechanical considerations during treatment or poor operator skills. Common issues include anchorage loss, deepening of bite, incorrect extraction protocols, re-opened extraction spaces and loss of vertical control. To address these problems, traditional orthodontic appliances, skeletal anchorage systems, customized appliances, and clear aligners may offer a ray of hope, provided they are used judiciously. To effectively manage re-treatment techniques, it's important to have a solid understanding of the anatomic limits, biomechanics, and potential side effects. Proper case selection is extremely crucial for overall clinical success in such complex situations. Therefore, establishing guidelines and understanding the biomechanical perspectives of various appliance systems are essential to address these challenges in modern orthodontic practice. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the accuracy of dental rotational movements using clear aligners with different attachment configurations. Materials and Methods: This retrospective study analysed 212 teeth from 89 patients undergoing Invisalign treatment. Digital models were analysed after the virtual treatment plan (ST1) and after the first treatment phase (ET1) to evaluate the effective clinical rotational movement. The rotational movements of incisors, canines, and bicuspids were measured using data from the Clincheck Movements Table. ST1 and ET1 were compared to determine the actual rotational movement achieved (ST1‐ET1). The presence or absence of attachments (rectangular or optimized) on teeth was analysed. The accuracy of rotational movements among attachment types was compared using the Kruskal‐Wallis test. Multiple linear regressions were conducted with accuracy as the dependent variable and tooth type, gender, and age as predictors. Results: Optimized attachments had the highest median accuracy (70%), followed by rectangular (65%), and without attachment (63%), with no significant differences (p =.5). There were no significant differences across age groups, genders, or tooth types. Baseline accuracy was 68.62% (95% CI: 56.03–81.20, p <.001). Age was a significant predictor (estimate = −0.30, 95% CI: −0.58 – −0.03, p =.032), indicating decreased accuracy with increasing age. The model's R2 was 0.046, with an adjusted R2 of 0.003, indicating minimal variance explained. Conclusion: The addition of attachment configurations to clear aligners improves rotational accuracy, but not significantly. Further advancements in these configurations are needed to enhance the performance of the aligners. [ABSTRACT FROM AUTHOR]

Objectives: This study aims to compare the achieved and predicted root movements in adults after four first‐premolar extractions and Invisalign treatment. Materials and Methods: Thirty‐three consecutive adults (22 Class I, 9 Cusp‐to‐cusp Class II and 2 Cusp‐to‐cusp Class III) from a single clinical division who completed the first series of aligners after premolar extractions were included in this retrospective study. A pretreatment cone‐beam computed tomography model was registered onto the pretreatment surface‐scanned dental model (SSDM) to locate the pretreatment root apices of the whole dentition. These were copied and transferred to the predicted and achieved post‐treatment SSDMs to acquire the locations of the predicted and achieved post‐treatment root apices. The differences between predicted and achieved root movements (DPARMs) were tested using the paired t‐test or Wilcoxon signed rank test. Results: In the anteroposterior direction, posterior root movements of maxillary and mandibular anterior teeth were poorly achieved (3.24–5.74 mm DPARMs, p <.05). In the vertical direction, roots of maxillary anterior teeth achieved greater intrusion (0.70–0.93 mm DPARMs, p <.05), while those of mandibular incisors achieved less intrusion (0.57–0.65 mm DPARMs, p <.05) than predicted. In the mediolateral direction, lateral incisor roots did not move distally (−0.65 to −0.96 mm DPARMs, p <.05), while those of canines did not move buccally, compared with the prediction (−0.75 mm DPARMs, p <.05). Conclusions: In the four first‐premolar extraction treatments with Invisalign, root movements were not achieved as predicted, particularly for anterior teeth in the anteroposterior direction. [ABSTRACT FROM AUTHOR]

Objective: To assess the tooth movement trends during the three stages of maxillary dentition distalization with clear aligners (CA) and to compare the efficacy of different mini‐screw anchorage systems. Materials and Methods: Three‐dimensional (3D) finite element models of three anchorage systems (A, control group; B, buccal mini‐screw anchorage group; C, palatal mini‐screw anchorage group) were established. Three stages of simulating maxillary dentition distalization with CA included maxillary molar distalization (stage 1), maxillary premolar distalization (stage 2) and maxillary anterior teeth retraction (stage 3). Therefore, a total of nine models were constructed to analyse the 3D displacement of maxillary teeth during the distalization process. Results: The displacement pattern of maxillary dentition during distalization was similar across the three groups, but with varying magnitudes. During stage 1, groups B and C exhibited greater amounts of molar distalization compared to group A. Group C also demonstrated the least amount of labial movement of the maxillary central incisor compared to the other two groups. During stage 2, the mesial displacement of the maxillary first molar was less significant in groups B and C than in group A. In the final stage, group C exhibited a greater amount of maxillary anterior retraction compared to groups A and B. Conclusion: The palatal mini‐screw anchorage system was effective in reducing anchorage loss and improving the efficacy of maxillary dentition distalization with CA. [ABSTRACT FROM AUTHOR]

The clear aligner, commonly utilized in orthodontic treatment for malocclusion, necessitates the quantification of orthodontic forces, which is highly demanded by doctors for enhancing risk management and treatment efficiency. However, the current technology still faces obstacles in achieving conformal integration of pressure sensors onto clear aligners with large curvature for the quantification and real‐time monitoring of orthodontic forces. In this paper, a conformal iontronic sensing clear aligner (CSA) is proposed based on flexible iontronic sensing mechanism, which conformally integrates the sensor with the aligner to quantify orthodontic forces throughout the treatment process while preserving the aligner's original function. Specifically, the ionic coating is seamlessly integrated onto the diaphragm by applying a layer of ionic paint before molding the clear aligner, while the sensing electrode array, designed using a kirigami‐based structure, is seamlessly adhered to the ionic coating. By integrating the CSA into a dental model, its exceptional sensitivity and precise pressure mapping capabilities have been demonstrated. This enables the identification of various tooth movement patterns, discernment of orthodontic force magnitude, and continuous monitoring of forces throughout the orthodontic treatment. Consequently, this research is expected to significantly advance risk management, outcome prediction, and treatment efficiency in orthodontic treatments. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to investigate the biomechanical effects of clear aligner (CA) with different shape designs at extraction space (CAES) area during space closing. Materials and Methods: A finite‐element method (FEM) model of mandibular dentition, periodontal ligaments, attachments, and corresponding CA was established. The connecting rod design of CAES was modelled for the control group. Eight test groups with different heights of CAES from −4 mm to +4 mm were designed. Tooth displacement tendencies were calculated. The maximum principal stress in PDLs, teeth, and CAs was analysed. Both global coordinate system and local coordinate system were also used to evaluate individual tooth movements. Results: Across all groups, stresses concentrated on the lingual outer surface of CAESs. For the lowered CAES groups, both the stress value and the stress distribution area at CAESs were increased. The lowered CAES groups showed reduced movement in anterior teeth and less tipping tendency of the canines. Conclusion: The shape of CAES has a biomechanical impact on anterior teeth movement and should be considered in aligner design. The results suggest that increasing the height of CAES can enhance anterior teeth retraction, while lowered CAES may facilitate controlled root movement. Changes in the shape of CAES represent a potential direction for biomechanical improvement of clear aligner in extraction cases and are worth exploring. [ABSTRACT FROM AUTHOR]

Background: The aim of the present study was to compare the vertical dimension changes, before and after treatment, in two groups of growing patients, one group treated with clear aligner therapy versus a group treated with Quad-helix and bite-block therapy. Methods: The studied sample was composed of n. 40 patients (20 females and 20 males with a mean age of 8.6 ± 1.8 years), enrolled from the Department of Orthodontics at Policlinico of Rome Tor Vergata. The original sample was randomly divided into two groups: Group IF (Invisalign First) and Group BB (Quad-helix and bite block). Pre- (T0) and post-treatment (T1 after 12 months) lateral cephalograms were collected from all the selected patients. Nine cephalometric parameters, both angular and linear, were measured and recorded for each cephalogram. Results: No statistically significant changes were found between both the IF and BB groups at T0, while statistically significant changes were observed in both groups (BB and IF) between T0 and T1 (after 12 months of active therapy), p < 0.005. Conclusions: Both therapies were able to control the patient's vertical condition. To date, the use of conventional appliances seems to have slightly better efficacy in controlling the vertical dimension than aligner therapy. [ABSTRACT FROM AUTHOR]

The increasing concern over environmental sustainability has prompted various industries to reassess their practices and explore greener alternatives. Dentistry, as a significant contributor to waste generation, is actively seeking methods to minimize its environmental footprint. This paper examines the environmental implications of clear aligner therapy (CAT) in orthodontics and explores strategies to prioritize sustainability in aligner manufacturing and usage. CAT has gained popularity as a viable alternative to traditional fixed appliances due to advancements in biomaterials and computer-aided design (CAD) and manufacturing (CAM) technologies. The global market for clear aligners is expanding rapidly, with significant growth projected in the coming years. To address these challenges, this paper proposes adopting the principles of reduce, reuse, recycle, and rethink (4Rs) in orthodontic practices. Strategies such as minimizing resource consumption, incorporating recycled materials, and promoting proper aligner disposal and recycling can significantly reduce environmental harm. This paper explores emerging technologies and materials to mitigate the environmental impacts of CAT. Additionally, initiatives promoting aligner recycling and repurposing offer promising avenues for reducing plastic waste and fostering a circular economy. In conclusion, while CAT offers numerous benefits in orthodontic treatment, its environmental impact cannot be overlooked. By implementing sustainable practices and embracing innovative solutions, the orthodontic community can contribute to a more environmentally conscious future while continuing to provide quality care to patients. [ABSTRACT FROM AUTHOR]

Introduction: The present study aimed to investigate the deformation behavior of three different clear aligner systems, CA® Pro+ Clear Aligner (Scheu Dental, Iserlohn, Germany), Taglus Premium (Taglus Company, Mumbai, India), and Spark Trugen (Ormco Corp., Orange, CA, USA), under compression testing, using the digital image correlation (DIC) technique. Materials and Methods: A total of 15 patients were treated with each of the three aligner systems, resulting in 45 sets of aligners. Each aligner set was fixed on the 3D-printed dental arches and then in an articulator. Then, the samples were subjected to occlusal forces using a purpose-built test stand to allow for controlled force application and precise displacement determination. The DIC technique was used for capturing the deformation behavior, providing detailed strain and displacement fields. Statistical analysis was performed using one-way ANOVA and Bonferroni post hoc tests with a significance of 0.05. Results: The results indicate that the Spark system exhibited the most substantial rigid displacement. Furthermore, the elastic deformation values of the Spark and Taglus systems were significantly higher than those of the CA Pro+ system (p > 0.05). Conclusions: The Spark Trugen clear aligner system demonstrated a lower stability to rigid displacement and elastic deformation under compression testing compared to the Scheu CA® Pro+ Clear Aligner and Taglus Premium. All three tested clear aligner systems showed an increased resistance to elastic displacement and rigid deformation in the mandibular arch. [ABSTRACT FROM AUTHOR]

This study aimed to compare the color changes in two different orthodontic clear aligner systems after submersion in various beverages for 14 days. The tested aligner systems were Taglus Premium made of polyethylene terephthalate glycol (the TAG group) and CA® Prodin+ made of a transparent copolyester and a thermoplastic elastomer (the PRO group). A total of 56 samples were firstly divided into two groups according to the tested system—TAG and PRO. Each group was subsequently divided in four subgroups according to immersion solution: A—artificial saliva, B—cola, C—coffee, D—red wine. Color measurements were performed on Days 1, 7 and 14 using a portable colorimeter and the CIE L*a*b* system. The obtained results showed significant color changes in both materials when exposed to coffee and red wine (p > 0.05). Samples in the PRO group showed a greater susceptibility to discoloration (higher ΔE values) when compared to the TAG group after submersion in cola (p = 0.025), coffee (p = 0.005) and red wine (p = 0.041) solutions. Statistical analysis revealed that all of the color parameters ΔL*, Δa*, Δb* and ΔE of both tested materials were affected by submersion in coffee solution for 14 days. In conclusion, the CA® Pro+ aligner system is more prone to staining compared to the Taglus material after submersion for 14 days in cola, coffee and red wine solutions. Submersion for 14 days in coffee solution alters all of the color parameters (ΔL, Δa, Δb and ΔE) of both tested aligner materials. [ABSTRACT FROM AUTHOR]

Introduction: The purpose of this study was to evaluate the therapeutic effect of modified clear Twin Block (CTB) aligner and traditional twin block (TB) appliance from skeletal, dentoalveolar and soft tissue changes in adolescents with skeletal class II malocclusion. Methods: A total of 80 adolescents, included in this study from two medical centres, were distributed into CTB group, TB group and control group based on the treatment they received. Lateral cephalograms at pre‐treatment (T1) and post‐treatment (T2) were measured by modified Pancherz's cephalometric analysis, and dentoskeletal and soft tissue changes were analysed by independent‐sample t‐test, paired‐sample t‐test, ANOVA test and Scheffe's Post Hoc test. Results: Seventy‐five adolescents completed the study, including 32 in the CTB group, 32 in the TB group and 11 in the control group. Both CTB and TB treatment showed significant differences in most dentoskeletal and soft tissue measurements. Compared with the control group, improvements were observed in class II molar relationship through significant different in S Vert/Ms‐S Vert/Mi in the CTB group (P <.01) and the TB group (P <.001), as well as deep overjet through significant different in S Vert/Is‐S Vert/Ii in the CTB group (P <.001) and the TB group (P <.001). Besides, the CTB group also showed less protrusion of lower incisors and resulted in a more significant improvement in profile with fewer adverse effects on speaking, eating and social activities. Conclusions: For adolescents with skeletal class II malocclusion, CTB appliance was as effective as TB on improving dentoskeletal and soft tissue measurements, featuring more reliable teeth control and patient acceptance. [ABSTRACT FROM AUTHOR]

Background: To evaluate the accuracy, reliability, quality, and readability of responses generated by ChatGPT-3.5, ChatGPT-4, Gemini, and Copilot in relation to orthodontic clear aligners. Methods: Frequently asked questions by patients/laypersons about clear aligners on websites were identified using the Google search tool and these questions were posed to ChatGPT-3.5, ChatGPT-4, Gemini, and Copilot AI models. Responses were assessed using a five-point Likert scale for accuracy, the modified DISCERN scale for reliability, the Global Quality Scale (GQS) for quality, and the Flesch Reading Ease Score (FRES) for readability. Results: ChatGPT-4 responses had the highest mean Likert score (4.5 ± 0.61), followed by Copilot (4.35 ± 0.81), ChatGPT-3.5 (4.15 ± 0.75) and Gemini (4.1 ± 0.72). The difference between the Likert scores of the chatbot models was not statistically significant (p > 0.05). Copilot had a significantly higher modified DISCERN and GQS score compared to both Gemini, ChatGPT-4 and ChatGPT-3.5 (p < 0.05). Gemini's modified DISCERN and GQS score was statistically higher than ChatGPT-3.5 (p < 0.05). Gemini also had a significantly higher FRES compared to both ChatGPT-4, Copilot and ChatGPT-3.5 (p < 0.05). The mean FRES was 38.39 ± 11.56 for ChatGPT-3.5, 43.88 ± 10.13 for ChatGPT-4 and 41.72 ± 10.74 for Copilot, indicating that the responses were difficult to read according to the reading level. The mean FRES for Gemini is 54.12 ± 10.27, indicating that Gemini's responses are more readable than other chatbots. Conclusions: All chatbot models provided generally accurate, moderate reliable and moderate to good quality answers to questions about the clear aligners. Furthermore, the readability of the responses was difficult. ChatGPT, Gemini and Copilot have significant potential as patient information tools in orthodontics, however, to be fully effective they need to be supplemented with more evidence-based information and improved readability. [ABSTRACT FROM AUTHOR]

Objectives: The purpose of this preliminary study was to determine the differences between planned and actual maxillary molar movements after the completion of treatment with an initial set of clear aligners including sequential maxillary molar distalization. Methods: The data records of 14 non-growing patients who completed orthodontic treatment with sequential maxillary molar distalization using clear aligners were retrospectively evaluated (n= 14, 4 males and 10 females, 33.61 ± 8.57 years). Data on planned tooth movements were obtained from ClinCheck software (ClinCheck Pro version 5.3). The amounts of actual tooth movements were obtained by performing superimposition of lateral cephalograms taken before and after treatment. The amounts of distal translation and tipping between planned and actual maxillary molar movements were compared with the paired Student's t-test. Results: The statistically significant differences between planned and actual translation movements of maxillary first and second molars were shown after completing treatment with the first series of aligners (p < 0.05). The average actual amount of molar distalization on maxillary first molars was less than the planned amount by 1.32 ± 0.42 mm. Similarly, the average actual amount of molar distalization on maxillary second molars was less than the planned amount by 1.57 ± 0.45 mm. The accuracy for molar distalization, namely, the percentage of actual distal translation to planned movement, was 40.11% for maxillary first molars and 35.39% for maxillary second molars. However, the difference between the planned and actual angulation movements was not significant (p > 0.05). Conslusions: In conclusion, the amounts of actual distal translation of maxillary molars through the utilization of clear aligners were significantly lower than planned. However, there were no statistically significant differences between the degrees of actual and planned molar angulation movement. [ABSTRACT FROM AUTHOR]

Background: Desirable molar distalization by bodily movement is challenging and can be difficult to achieve. This study investigated changes in molar angulation (mesiodistal tipping), molar inclination (buccolingual torque) and rotation during distalization using clear aligner therapy (CAT). Materials and methods: This retrospective study included 38 cone beam computed tomographic images (CBCTs) taken for patients treated with molar distalization using CAT. The study evaluated pre- (T0) and post-treatment (T1) CBCTs of 19 adult patients (36.68 ± 13.50 years) who underwent maxillary molar distalization using Invisalign® aligners (Align Technology, Inc., San José, CA, USA) with a minimum of 2 mm distalization. Changes in maxillary molar tip, torque and rotation were measured for 61 molars (183 roots). Paired t-test was used to evaluate the differences between pre- and post-treatment readings. The level of significance was set at p ≤ 0.05. The reproducibility of measurements was assessed by the intraclass correlation coefficient (ICC). Results: Molar angulation did not show significant change after distalization (p = 0.158) however, there was significant increase in buccal molar inclination (p = 0.034) and mesiobuccal molar rotation (p < 0.001). Conclusion: Molar distalization of 2 mm did not cause significant molar tipping. Maxillary molars showed significant buccal inclination (increased torque) and mesiobuccal rotation after distalization. [ABSTRACT FROM AUTHOR]

The study investigated the effects of temperature and centrifugation time on the efficacy of removing uncured resin from 3D-printed clear aligners. Using a photo-polymerizable polyurethane resin (Tera Harz TC-85, Graphy Inc., Seoul, Korea), aligners were printed and subjected to cleaning processes using isopropyl alcohol (IPA) or centrifugation (g-force 27.95g) at room temperature (RT, 23 °C) and high temperature (HT, 55 °C) for 2, 4, and 6 min. The control group received no treatment (NT). Cleaning efficiency was assessed through rheological analysis, weight measurement, transparency evaluation, SEM imaging, 3D geometry evaluation, stress relaxation, and cell viability tests. Results showed increased temperature and longer centrifugation times significantly reduced aligner viscosity, weight (P < 0.05), and transmittance. IPA-cleaned aligners exhibited significantly lower transparency and rougher surfaces in SEM images. All groups met ISO biocompatibility standards in cytotoxicity tests. The NT group had higher root mean square (RMS) values, indicating greater deviation from the original design. Stress relaxation tests revealed over 95% recovery in all groups after 60 min. The findings suggest that a 2-min HT centrifugation process effectively removes uncured resin without significantly impacting the aligners' physical and optical properties, making it a clinically viable option. [ABSTRACT FROM AUTHOR]

Background: The intrusion of maxillary anterior teeth is often required and there are various intrusion modes with mini-implants in clear aligner treatment. The objective of this study was to evaluate the effectiveness of maxillary anterior teeth intrusion with different intrusion modes, aiming to provide references for precise and safe intrusion movements in clinical practice. Methods: Cone-beam computed tomography and intraoral optical scanning data of a patient were collected. Finite element models of the maxilla, maxillary dentition, periodontal ligaments (PDLs), clear aligner (CA), attachments, and mini-implants were established. Different intrusion modes of the maxillary anterior teeth were simulated by changing the mini-implant site (between central incisors, between central and lateral incisor, between lateral incisor and canine), loading site (between central incisors, on central incisor, between central and lateral incisor, between lateral incisor and canine), and loading mode (labial loading and labiolingual loading). Ten conditions were generated and intrusive forces of 100 g were applied totally. Then displacement tendency of the maxillary anterior teeth and CA, and stress of the PDLs were analyzed. Results: For the central incisor under condition L14 and for the canine under conditions L11, L13, L23, and L33, the intrusion amount was negative. Under other conditions, the intrusion amount was positive. The labiolingual angulation of maxillary anterior teeth exhibited positive changes under all conditions, with greater changes under linguoincisal loading. The mesiodistal angulation of canine exhibited positive changes under labial loading, while negative changes under linguoincisal loading except for condition L14. Conclusions: The intrusion amount, labiolingual and mesiodistal angulations of the maxillary anterior teeth were affected by the mini-implant site, loading site, and loading mode. Labial and linguoincisal loading may have opposite effects on the intrusion amount of maxillary anterior teeth and the mesiodistal angulation of canine. The labiolingual angulation of the maxillary incisors would increase under all intrusion modes, with greater increases under linguoincisal loading. [ABSTRACT FROM AUTHOR]

The composite attachment loss during orthodontic clear aligner therapy is an adverse event that commonly happens in clinical practice and can affect the overall outcome and length of treatment. The aim of our research is to provide a basis for the further study of an innovative digital protocol and application method for orthodontic aligner attachments. Two 3D models were designed, one based on the proposed protocol and the other on the conventional method for aligner attachment application. Four attachment shapes were used to identify the maximum values for the von Mises equivalent stresses, the maximum displacements values and the areas in which these values were recorded through FEM analysis. The results of the mechanical simulation show lower values of von Mises stress recorded in the 3D printed attachments assemblies, independent of their shape, when simulated under the same boundary and load conditions. The trapezoidal prism shaped 3D printed model has a 3.7 times smaller displacement value (0.088 [mm]) compared to the adhesive resin model (0.326 [mm]). In conclusion, the proposed protocol for aligner attachments and the introduction of innovative materials is a promising method of solving conventional attachment problems in current orthodontic treatments. [ABSTRACT FROM AUTHOR]

Background: to evaluate the predictability of expansion achieved in patients in early mixed dentition treated with Clear Aligners (CA), analyzing the efficiency of the expansion at the end of the first set of aligners and at the end of the therapy in the upper and lower arch. Methods: 36 patients (20 F, 16 M; mean age 8.3 ± 1.5 years) were selected retrospectively from the Department of Orthodontics of the Hospital of Rome "Tor Vergata". All subjects were treated with CA with no other auxiliaries than attachments. For each patient a standardized sequential expansion protocol was planned for both arches. Digital dental casts were created at three observation periods from an intraoral scanner: prior to treatment (T0), at the end of the first set of aligners (T1), at the end of treatment (T2). The 3D models in planned position determined by the first Clincheck (CC) were obtained for comparison with T1 and T2. Six linear transversal measurements were used to evaluate the dimensional changes and the predictability of expansion movements, comparing T1-CC and T2-CC. Results: a statistically significant increase within the pre-treatment and the final outcomes for all the variables examined was found. In the upper arch, the greatest level of predictability was detected at the level of the first (46.44%) and second deciduous molar width (44.95%) at T1. The analysis of T2-CC changes showed a significant increase in the percentage of predictability of expansion at the level of the first permanent molars, at mesial (54.86%) and distal (58.92%) width. In the lower arch, a higher percentage of predictability than the upper arch was reported at T1-CC and T2-CC, with the greatest values at the level of second (T1-CC: 48.70%; T2-CC: 75.32%) and first deciduous molar width (T1-CC: 45.71%; T2-CC: 72.75%). Conclusions: CA can induce significant transversal increments. The predictability of expansion is variable, but it did not exceed the 50% during the first set of aligners. It was necessary to apply refinement set to achieve a good predictability for expansion of about 70%. The expansion in the lower arch was observed to be more predictable than in the upper arch. [ABSTRACT FROM AUTHOR]

Purpose: Stereolithography (SLA) additive manufacturing (AM) technique has enabled the production of inconspicuous and aesthetically pleasing orthodontics that are also hygienic. However, the staircase effect poses a challenge to the application of invisible orthodontics in the dental industry. The purpose of this study is to implement chemical postprocessing technique by using isopropyl alcohol as a solvent to overcome this challenge. Design/methodology/approach: Fifteen experiments were conducted using a D-optimal design to investigate the effect of different concentrations and postprocessing times on the surface roughness, material removal rate (MRR), hardness and cost of SLA dental parts required for creating a clear customized aligner, and a container was constructed for chemical treatment of these parts made from photocurable resin. Findings: The study revealed that the chemical postprocessing technique can significantly improve the surface roughness of dental SLA parts, but improper selection of concentration and time can lead to poor surface roughness. The optimal surface roughness was achieved with a concentration of 90 and a time of 37.5. Moreover, the dental part with the lowest concentration and time (60% and 15 min, respectively) had the lowest MRR and the highest hardness. The part with the highest concentration and time required the greatest budget allocation. Finally, the results of the multiobjective optimization analysis aligned with the experimental data. Originality/value: This paper sheds light on a previously underestimated aspect, which is the pivotal role of chemical postprocessing in mitigating the adverse impact of stair case effect. This nuanced perspective contributes to the broader discourse on AM methodologies, establishing a novel pathway for advancing the capabilities of SLA in dental application. [ABSTRACT FROM AUTHOR]

A rising number of individuals are exploring alternatives to traditional orthodontic appliances as the demand for aesthetically pleasing treatments continues to grow. Over the past decade, clear aligners have emerged as a popular and attractive option for orthodontic correction, offering both effectiveness and discretion. This paper provides an indepth analysis of the Mysmartalign system, a widely adopted clear aligner technology, to highlight the critical role of accurate case selection in achieving optimal outcomes. The Mysmartalign system utilizes advanced 3D imaging and digital modeling to create custom aligners that address a range of orthodontic issues, from minor spacing and crowding to more complex alignment challenges. The paper will explore the technological innovations behind Mysmartalign, including its predictive software and personalized treatment planning. Furthermore, it will discuss common case types suitable for clear aligner treatment and the factors that influence successful results, such as patient compliance, aligner fit, and treatment duration. By emphasizing the significance of appropriate case selection and management, this article aims to provide valuable insights for orthodontists and dental professionals in optimizing clear aligner therapy with the Mysmartalign system. The discussion will also cover best practices for patient assessment and the integration of clear aligners into broader orthodontic treatment plans. [ABSTRACT FROM AUTHOR]

BACKGROUND: There is an increasing demand for orthodontic treatment, and periodontally accelerated osteogenic orthodontics (PAOO) technique can make it possible to move orthodontic teeth that are limited by thin alveolar bone. OBJECTIVE: To investigate the biomechanics of orthodontic tooth movement before and after periodontally accelerated osteogenic orthodontics (PAOO) surgery to increase alveolar bone volume using the three-dimensional finite element method. METHODS: A patient undergoing PAOO surgery before orthodontic treatment to increase bone volume on the labial side of the mandibular anterior region was selected. The patient was under invisible orthodontics. Two three-dimensional finite element models were constructed based on the patient’s preoperative and 6-month postoperative cone beam CT data. Both models simulated the movement of tooth 33: experiment I: distal-central movement of 0.25 mm; experiment II: lingual movement of 0.25 mm; and experiment III: intrusion movement of 0.10 mm. The stress distribution and initial displacement trend of tooth 33, periodontal ligament and surrounding alveolar bone under the action of the invisible aligner were analyzed before and after the PAOO procedure. RESULTS AND CONCLUSION: Dental stress analysis: In the same orthodontic tooth movement, the maximum Von-Mises stress and overall stress values of tooth 33 were all higher before surgery than after surgery; there were similar distribution areas of maximum equivalent stress and overall distribution trends of Von-Mises stress before and after surgery. Periodontal ligament stress analysis: In the same orthodontic tooth movement, the maximum Von-Mises stress and overall stress values of the periodontal ligament were higher before surgery than after surgery, and there were similar distribution areas of the maximum equivalent stress and overall distribution trends of Von-Mises stress before and after surgery. Alveolar bone stress analysis: In the same orthodontic tooth movement, the maximum Von-Mises stress values of the alveolar bone around tooth 33 were higher before surgery than after surgery, while the equivalent stress distribution showed a gradual decrease from the top of the alveolar ridge to the root. Initial displacement analysis: In the same orthodontic tooth movement, the initial displacements in the main displacement direction for all six observation points of tooth 33 were smaller before surgery than after surgery, and showed a tendency to gradually decrease from the tooth tip to the apex. Therefore, there were differences in the biomechanical characteristics of orthodontic tooth movement before and after the PAOO surgery. With the clear aligner, the postoperative equivalent stress values on the dentition, periodontal ligament, and surrounding alveolar bone were lower than before the surgery, and the initial displacements of the orthodontic teeth after the surgery are larger than before. These findings suggest that PAOO can release the restriction of thin alveolar bone on the movement of orthodontic tooth by increasing alveolar bone thickness, effectively improving the force on the roots, periodontal ligament, and alveolar bone, avoiding the stress concentration on orthodontic tooth in the thin alveolar bone area that can cause complications when moving, and improving the efficiency of tooth movement. [ABSTRACT FROM AUTHOR]

Background: The introduction of auxiliaries such as composite attachment has improved the force delivery of clear aligner (CA) therapy. However, the placement of the attachment may give rise to a flash, defined as excess resin around the attachment which may affect CA force delivery. This in vitro study aims to determine the differences in the force generated by the attachment in the presence or absence of flash in CA. Materials and methods: Tristar Trubalance aligner sheets were used to fabricate the CAs. Thirty-four resin models were 3D printed and 17 each, were bonded with ellipsoidal or rectangular attachments on maxillary right central incisors. Fuji Prescale pressure film was used to measure the force generated by the attachment of CA. The images of colour density produced on the films were processed using a calibrated pressure mapping system utilising image processing techniques and topographical force mapping to quantify the force. The force measurement process was repeated after the flash was removed from the attachment using tungsten-carbide bur on a slow-speed handpiece. Results: The intraclass correlation coefficient showed excellent reliability (ICC = 0.96, 95% CI = 0.92–0.98). The average mean force exerted by ellipsoidal attachments with flash was 8.05 ± 0.16 N, while 8.11 ± 0.18 N was without flash. As for rectangular attachments, the average mean force with flash was 8.48 ± 0.27 N, while 8.53 ± 0.13 N was without flash. Paired t-test revealed no statistically significant difference in the mean force exerted by CA in the presence or absence of flash for both ellipsoidal (p = 0.07) and rectangular attachments (p = 0.41). Rectangular attachments generated statistically significantly (p < 0.001) higher mean force than ellipsoidal attachments for flash and without flash. Conclusion: Although rectangular attachment generated a significantly higher force than ellipsoidal attachment, the force generated by both attachments in the presence or absence of flash is similar (p > 0.05). [ABSTRACT FROM AUTHOR]

The aesthetic advances associated with clear aligner therapy (CAT) encourage the adult population, often affected by periodontal disease (PD), to seek orthodontic treatment. The literature states that it is possible to conduct orthodontic treatment in patients with compromised periodontal tissue through fixed appliances (FA) if the inflammation is controlled. It is now necessary to elucidate the role of CAT in this context. This narrative review aims to discuss the impact of orthodontic treatment with CAT in patients with healthy and compromised periodontal tissue. Regarding periodontal health, there is no evidence showing differences in the levels of periodontal disease pathogens in the oral microbiome of FA and CAT users. The presence or type of orthodontic appliance may not result in poor periodontal health among adolescents and adults with good oral hygiene and the absence of systematic conditions associated with PD. The predisposition to PD is highly associated with individual factors, including oral hygiene habits, smoking and hormonal changes, rather than the type of brackets. Considering patients with compromised periodontal tissue without active inflammation, CAT is a viable treatment option that can provide good periodontal health indices, in the same way as the treatment performed with FA. More important than the type of appliance are individual factors, including oral hygiene habits, clinical control of the periodontal condition, and the orthodontic biomechanics performed. New randomized clinical studies, which evaluate the effects of hygiene control and patient-related factors, may elucidate this issue. [ABSTRACT FROM AUTHOR]

Background and Objectives: Clear aligners‐related posts are popularized on social media platforms to educate patients and peers and to market aligners in dental practices. This study aimed to characterize the account credentials and content of the top‐performing posts to understand the spread of clear aligners‐related information on Instagram. Materials and Methods: This cross‐sectional web‐based study analysed 13 Instagram clear aligners‐related hashtags. Content analysis was performed for the "Top 10 posts" listed under the "Top" section for each hashtag within Instagram, as sorted by Instagram's algorithm. Data were analysed for the poster's background, credentials, role, post format, content, and engagement level ratio. Duplicate posts and those not relevant to clear aligners were excluded. Quantitative and qualitative analyses of the collected data were conducted. Results: A total of 29 192 596 posts mentioned the selected hashtags, of which 130 posts were screened in this study. Most posts were authored by dentists (n = 84), 79.8% of them were orthodontic specialists. Self‐promotional posts comprised 90.2%, while educational posts accounted for only 8.9%. Interestingly, the number of likes and comments received on posts by patients (n = 19, median = 112, IQR = 340) was significantly higher than those posted by dentists (n = 84, median = 93, IQR = 81.75) (P =.004). Conclusion: More than 29 million posts about clear aligners were identified on Instagram. Orthodontists are the leading authors of aligners hashtags. However, the majority of the posts are self‐promotional and have nonfactual information. Social media awareness among orthodontic specialists may help provide more evidence‐based content about clear aligners and can act as an interactive networking and health communication platform. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to assess the loss rate of attachments and investigate its probable influencing factors in patients during orthodontic therapy with clear aligners. Materials and Methods: A total of 55 patients treated with clear aligners were enrolled in this prospective clinical study. The loss rate of attachments was evaluated after a 6‐month follow‐up since the initial bonding was finished. The attachment survival curves were gone through Kaplan–Meier estimates. The Cox regression model with shared frailty was conducted to evaluate the hazard ratios (HRs) for the following factors, including sex, age, dental malocclusion, vertical skeletal pattern, anterior overbite, operators, tooth extraction, attachment amount, arch, tooth position and attachment type. Results: There were a total of 47 patients (14 males and 33 females; and mean age: 26.77 ± 8.45) in which 722 attachments were involved in the final analysis. During the 6‐month follow‐up, 99 attachments were lost by 40 participants. The overall loss rate was 13.7%. The loss of attachments was more common in the early months of therapy. During the first 2 months, 71 attachments were lost. The loss rate of attachments was not significantly affected by sex, age, dental malocclusion, vertical skeletal pattern, anterior overbite, operators, tooth extraction, attachment amount and attachment type (P > 0.05). The loss rate of mandibular attachments was 1.8 times that of maxillary attachments (HR = 1.8; 95% CI: 1.2–2.8; P = 0.009). The loss rate of molar attachments was 5.5 times that of incisor attachments (HR = 5.5; 95% CI: 1.6–19; P = 0.007). Conclusion: During the first 6 months, the overall loss rate of attachments was 13.7%. In the early months of therapy, loss of attachments was more common. The loss rate decreased as treatment time increased. Loss of attachments was significantly affected by arch and tooth position, with higher loss rates in the mandibular arch and molars. Besides, loss of attachments was not affected by sex, age, dental malocclusion, vertical skeletal pattern, anterior overbite, operators, tooth extraction, attachment amount and attachment type. [ABSTRACT FROM AUTHOR]

Background.: This study explored the layperson's perception of comfort, satisfaction, and willingness to use various accessories in clear aligner therapy. Methods.: A total of 267 people analyzed standardized intraoral photographs of a female model in orthodontic treatment using: 1) only clear aligner (CA), the control group; 2) clear aligner+attachments (AT); 3) clear aligners+Cl II elastics (EL); 4) clear aligner+hybrid treatment with esthetic braces (HEB); 5) Clear aligner+hybrid treatment with metallic braces (HMB); 6) clear aligner+mini-implants (MI); 7) clear aligner+mini-implants and elastics for intrusion (MIE). In addition, a social media questionnaire was distributed to assess the willingness to undergo orthodontic treatment with various accessories. Results.: There was a significant difference between CA and all the other groups (P Conclusion.: The CA was the most comfortable, exhibiting a higher satisfaction rate and a greater willingness to use it. The AT therapy was perceived as more comfortable and was associated with higher satisfaction and a greater likelihood of use, especially if it resulted in reduced treatment time. On the other hand, the participants reported that the HMB, MI, and MIE accessories were less comfortable. [ABSTRACT FROM AUTHOR]

Background: This prospective clinical study aimed to quantitatively evaluate the surface wear of attachments and investigate the associated risk factors. Additionally, the wear values and regions of three types of commonly used attachments were explored. Methods: Participants were recruited from the population of patients who received clear aligner therapy from October to December 2022. Intraoral scanning was performed on eligible participants before treatment (T0), immediately after initial bonding of attachments (T1), and at 2 months (T2), 4 months (T3), 6 months (T4), and 8 months (T5) after starting treatment. The attachment volume, average depth and regions of attachment wear were measured using superimposed digitized models. The Kruskal–Wallis test was performed to compare data between multiple groups. Multiple linear regression analyses were performed to evaluate risk factors for the volume of attachment wear. Results: A total of 47 patients with 617 attachments were included. As treatment time increased, the attachment volume decreased significantly (P = 0.003). The initial attachment volume was positively related to the volume of attachment wear (β = 0.527, P < 0.001). The volume of attachment wear was significantly greater in females than in males (β = 0.147, P = 0.020) and in optimized attachments than in conventional attachments (β = 0.308, P < 0.001). The wear of 3-mm rectangular attachments progressed from edges to buccal surfaces, with the deepest wear at corners of gingival edges; the wear of the optimized attachments was primarily located on surface ridges. The wear volume ratio of the optimized root control attachments was significantly greater than that of the 3-mm rectangular attachments at T3 (P = 0.011), T4 (P < 0.001), and T5 (P < 0.001). Conclusions: The volume of attachment wear increased gradually with treatment time. Sex, attachment type, and initial attachment volume were risk factors for the volume of attachment wear. The deepest wear regions of 3-mm rectangular attachments were at the corners of gingival edges, while the deepest wear regions of optimized attachments were at surface ridges. Four months after treatment, optimized root control attachments showed more relative wear than 3-mm rectangular attachments. [ABSTRACT FROM AUTHOR]

To evaluate the biomechanical system of molar distalization with clear aligner therapy (CAT) combined with angel button using interradicular mini-implants (IRMIs) with varying elastic forces. FE models including maxilla, complete maxillary dentition, periodontal ligaments (PDL), composite attachments, mini-implants (MI), and dedicated orthodontic aligner, were constructed. Three groups were created in accordance with the sagittal position of MI. Elastic forces (0 N,1 N,1.5 N,2 N) were applied. CAT without elastics caused labial tipping and intrusion of the anterior teeth. Initial labial tipping and the von Mises stress of the maxillary anterior teeth decreased as the elastic forces increased. [ABSTRACT FROM AUTHOR]

(1) Background: This study aims to investigate, within a controlled laboratory environment, the magnitude of the transversal load and the force decay over time produced by clear aligners in comparison to a Rapid Palatal Expander (RPE). (2) Methods: Resin models of a dental maxillary arch, additively manufactured from an intraoral scan, were inserted in a testing machine with uniaxial load cells to measure the force trend over time expressed by RPE and clear aligners. The mechanical load was recorded during a certain timeframe for both appliances. (3) Results: The force expressed by the RPE ranged from 30 to 50 N for each activation, decreasing with a nonlinear pattern over time. The force expressed by the clear aligner ranged from 3 to 5 N, decreasing with a linear pattern over time. In contrast, the force generated by the clear aligner fell within the range of 3 to 5 N, showing a linear reduction in force magnitude over the observed period of time. (4) Conclusions: The RPE exerted a force magnitude approximately ten times greater than that generated by clear aligners. Nevertheless, it is essential to acknowledge that the oral environment can significantly influence these results. These limitations underscore the need for caution when applying these findings to clinical settings. [ABSTRACT FROM AUTHOR]

Objective: To investigate the effect of sequential distalization on increasing gaps in the maxillary anterior teeth, focusing on the control of torque and three-dimensional teeth movement during anterior retraction with clear aligners in extraction cases. Methods: We recruited 24 patients who were undergoing extraction bilateral maxillary first premolars with clear aligners. According to a predetermined increment in the spaces between the maxillary anterior teeth, the patients were divided into three groups: those with no gap (9 cases), a 0.5 mm gap (6 cases) and a 1.0 mm gap (9 cases). In each group, a 2.0 mm en-mass retraction was applied on the anterior teeth. Plaster casts of the upper full dentition were obtained both before and after a 2 mm retraction. The palatal folds were used to overlap each pair of models. The three-dimensional movement of the teeth and the change of torque for the anterior teeth were subsequently analyzed using Geomagic Studio 2014 software. Results: The change in torque in the groups with added gaps was significantly smaller than that in the group with no gaps (P < 0.05). There was no significant difference in this respect when comparing the group with a 0.5 mm gap added to the group with a 1.0 mm gap was added (P > 0.05). In the labial-lingual and vertical directions, the displacements of the central and lateral incisors were smaller in the groups with additional gaps compared to those in the groups without gaps (P < 0.05). However, there was no significant difference observed when comparing the group with a 0.5 mm added gap to the group with a 1.0 mm added gap (P > 0.05). Then, a comparison was made between the displacement of the second premolar to the second molar in the mesial-distal direction across all groups. The study revealed that the anchorage molars in the group without gaps demonstrated significantly smaller displacement compared to those in the group with additional gaps (P < 0.05). Conclusion: Advantages were observed in controlling the torque of the anterior teeth and achieving a desired pattern closer to normal bodily movement by sequentially distalizing the maxillary anterior teeth gaps. Increasing the gaps between the maxillary anterior teeth also resulted in improved control of the vertical direction of the anterior teeth. However, this retraction strategy necessitates substantial protection of the anchorage molars. [ABSTRACT FROM AUTHOR]

Objective: To investigate the effect of micro-implant anchorage combined with a clear aligner on the efficiency of mandibular molar distalization and the protection of anterior teeth anchorage, provide reference for clinical scheme design. Methods: This is a prospective study. Seventeen patients who were treated in the Orthodontics Department of the Hospital of Stomatology affiliated to Fujian Medical University from 2019 to 2021 and used Invisalign clear aligners to move mandibular molars distally were included and divided into two groups according to anchorage types: Group-A and Group-B. Group-A (ten cases) were treated without micro-implant anchorage, while Group-B (seven cases) were treated with micro-implant anchorage nails for enhanced anchorage. The effect of micro-implant anchorage on crown and root distal movement of mandibular molars and the difference in three-dimensional movement between mandibular molars and mandibular central incisors were analyzed. Results: The crown distalization efficiency of mandibular first and second molars in Group-B was 68.66% and 71.02%, respectively, which were higher than those in Group-A(p<0.05). The mandibular central incisors in Group-A showed labial displacement and a small amount of elongation, while those in Group-B showed less anchorage loss(p<0.05). In Group-A, the crown was tilted in the distal direction and moved in the buccal direction during mandibular molar distalization(p<0.05). While in Group-B, the crown was tilted in the distal directio (p<0.05) and the mandibular second molar was depressed(p<0.05). Conclusion: In the process of mandibular molar distalization assisted by micro-implant anchorage combined with a clear aligner, better protects the anchorage of the mandibular central incisor and improves the efficiency of the molar crown distalization. [ABSTRACT FROM AUTHOR]

The external apical root resorption that occurs during orthodontic treatment was the focus of this study, using either fixed appliances (FA) or clear aligners (CA). Using the Boolean keywords "APICAL ROOT RESORPTION" and "CLEAR ALIGNERS", the study searched PubMed, Scopus, and Web of Science, with a restriction to English-language publications. A total of 50 publications were found by the computerized search, but after eliminating duplicates, completing reviews, and determining eligibility, only 9 papers could be used in the study. In conclusion, apical root resorption (ARR) is a frequent consequence of orthodontic tooth movement that mainly affects the lower incisors, which may compromise the success of the procedure and the health of the patient's teeth. Several variables, including the type of tooth, have an impact on the severity of ARR. [ABSTRACT FROM AUTHOR]

Background: Mesial tipping of posterior teeth occurs frequently during space closure with clear aligners (CAs). In this study, we proposed a new modification of CA by localized thickening of the aligner to form the enhanced structure and investigate its biomechanical effect during anterior retraction. Methods: Two methods were employed in this study. First, a finite element (FE) model was constructed, which included alveolar bone, the first premolars extracted maxillary dentition, periodontal ligaments (PDL), attachments and aligners. The second method involved an experimental model—a measuring device using multi-axis transducers and vacuum thermoforming aligners. Two groups were formed: (1) The control group used common CAs and (2) the enhanced structure group used partially thickened CAs. Results: FE model revealed that the enhanced structure improved the biomechanics during anterior retraction. Specifically, the second premolar, which had a smaller PDL area, experienced a smaller protraction force and moment, making it less likely to tip mesially. In the same vein, the molars could resist movement due to their larger PDL area even though they were applied larger forces. The resultant force of the posterior tooth was closer to the center of resistance, reducing the tipping moment. The canine was applied a larger retraction force and moment, resulting in sufficient retraction of anterior teeth. The experimental model demonstrated a similar trend in force variation as the FE model. Conclusions: Enhanced structure allowed force distribution more in accordance with optimal principles of biomechanics during the extraction space closure while permitting less mesial tipping and anchorage loss of posterior teeth and better retraction of anterior teeth. Thus, enhanced structure alleviated the roller coaster effect associated with extraction cases and offered a new possibility for anchorage reinforcement in clear aligner therapy. [ABSTRACT FROM AUTHOR]

Background: The aim of this study is to conduct a comparative evaluation of different designs of clear aligners and examine the disparities between clear aligners and fixed appliances. Methods: 3D digital models were created, consisting of a maxillary dentition without first premolars, maxilla, periodontal ligaments, attachments, micro-implant, 3D printed lingual retractor, brackets, archwire and clear aligner. The study involved the creation of five design models for clear aligner maxillary anterior internal retraction and one design model for fixed appliance maxillary anterior internal retraction, which were subsequently subjected to finite element analysis. These design models included: (1) Model C0 Control, (2) Model C1 Posterior Micro-implant, (3) Model C2 Anterior Micro-implant, (4) Model C3 Palatal Plate, (5) Model C4 Lingual Retractor, and (6) Model F0 Fixed Appliance. Results: In the clear aligner models, a consistent pattern of tooth movement was observed. Notably, among all tested models, the modified clear aligner Model C3 exhibited the smallest differences in sagittal displacement of the crown-root of the central incisor, vertical displacement of the central incisor, sagittal displacement of the second premolar and second molar, as well as vertical displacement of posterior teeth. However, distinct variations in tooth movement trends were observed between the clear aligner models and the fixed appliance model. Furthermore, compared to the fixed appliance model, significant increases in tooth displacement were achieved with the use of clear aligner models. Conclusions: In the clear aligner models, the movement trend of the teeth remained consistent, but there were variations in the amount of tooth displacement. Overall, the Model C3 exhibited better torque control and provided greater protection for posterior anchorage teeth compared to the other four clear aligner models. On the other hand, the fixed appliance model provides superior anterior torque control and better protection of the posterior anchorage teeth compared to clear aligner models. The clear aligner approach and the fixed appliance approach still exhibit a disparity; nevertheless, this study offers a developmental direction and establishes a theoretical foundation for future non-invasive, aesthetically pleasing, comfortable, and efficient modalities of clear aligner treatment. [ABSTRACT FROM AUTHOR]

The objective of this study was to examine how various anchorage methods impact long-term maxillary whole arch distalization using clear aligners (CAs) through an automated staging simulation. Three different anchorage reinforcement methods, namely, Class II elastics, buccal temporary anchorage device (TAD), and palatal TAD, were designed. Orthodontic tooth movement induced by orthodontic forces was simulated using an iterative computation method. Additionally, the automatic adjustment of the CA was simulated through the application of the thermal expansion method. The results indicated that the palatal TAD group had the largest retraction of incisors, followed by the buccal TAD group and the Class II elastic group, while the least was in the control group. The largest distal displacements and efficiency of molar distalization for the first and the second molars were noticed in the palatal TAD group. Arch width increased at the molar and premolar levels in all groups. The FEM results suggested palatal TAD had the best performance considering anterior teeth anchorage maintenance, both sagittally and vertically. However, attention should be paid to the possible increasement of arch width. [ABSTRACT FROM AUTHOR]

Introduction: Clear aligners have increased in popularity as an alternative to conventional fixed equipment in orthodontic treatment. However, the impact of clear aligner orthodontic therapy on the periodontium, particularly the periodontal tissues, has generated curiosity in research. Aim: This study aimed to evaluate the relationship between clear aligner orthodontic treatment and the height of the alveolar bone level. Materials and Method: Ninety-two panoramic radiographs (pretreatment and posttreatment) from 46 adult patients treated with clear aligner therapy were selected for the current study. Linear measurements have been performed in the panoramic radiographs to measure the alveolar bone. Patient data, including age, gender, type of malocclusion, duration of the orthodontic treatment, interproximal striping done or not during the orthodontic treatment, and changes in alveolar bone level in millimeters, were documented. Results and Discussion: Posttreatment significantly increased alveolar defects (p=<0.001). Moreover, the pretreatment and posttreatment alveolar bone defect was compared in different teeth that showed that significant difference in teeth #21(p=0.007), #17(p=0.006), #31(p<0.001), #32(p=0.011), #33(p =0.003), #41(p <0.001), #42(p =0.003) and #44(p<0.001), #45(p <0.001) and #46 (p=0.009). Comparison of pretreatment and posttreatment alveolar bone defects also showed significant differences in patients with interproximal striping (p=<0.001). Other variables exhibited no significant differences (p>0.05). Pretreatment and posttreatment mean differences in alveolar bone defects were statistically significant across all the studied variables (p<0.05) except in the Class III malocclusion (p=0.082). Moreover, there is a significant positive correlation observed between the age of the study participants and pretreatment (p=0.007) and posttreatment bone defects (p=0.002) along with pretreatment and posttreatment alveolar bone defect (p= <0.001). Conclusion: This study advances the understanding of the complexities surrounding malocclusion, clear aligner orthodontic treatment, and alveolar bone height. [ABSTRACT FROM AUTHOR]

Aim and Objective: To assess the dentist perception of efficiency, treatment outcome, and stability of the tooth movement treated with mysmartalign clear aligner therapy (MSA CAT). Materials and Method: A cross-sectional webbased questionnaire survey was carried out to evaluate the dentist perception of MYSMARTALIGN (MSA). To determine the sample size, a pilot study has been carried out and the final sample arrived was 4990 subjects. The current study's inclusion criteria took into account those who had finished their BDS and MDS as well as dentists and orthodontists who had been using the MSA CAT system on their patients for the previous 7 years. Results: The result of the study showed that most research participants (3650) used MSA to treat mild to moderate malocclusion, and 3996 participants said that initial digital treatment plans have been authorised with no revisions. In view of efficiency, 3894 doctors were satisfied with the final outcome. Conclusions: Finally concluded that recent survey showed that dentists were very satisfied with the effectiveness and treatment results of the MSA clear aligner procedure. [ABSTRACT FROM AUTHOR]

Background: In the present study, the effects of distalizations of one and two molars with different step distances and attachment designs have been analyzed. Methods: A 3D finite element analysis model has been developed in order to determine the tendency of tooth displacement and stress distribution with clear aligner treatment. Results: Under the condition of single-molar distalization, when the step distance was set to 0.25 mm, the total displacement was 0.086 mm for central incisors, 0.080 mm for lateral incisors, 0.084 mm for canines, 0.102 mm for the first premolar and 0.076 mm for the second premolar. The von Mises stress of roots and the principal stress of the periodontal ligament was slightly lower than in the control group when the step distance was set to 0.130 mm. Under the condition of two-molar distalization, when the step distance was set to 0.130 mm, the total displacements for central incisors, lateral incisors and canines as well as both the first and second maxillary molars were basically the same as with a distance of 0.250 mm for one-molar distalization. In addition, when the step distance was 0.130 mm with two-molar distalization, the rotation center of the first and second molar was closer to the apex of the root indicating that the smaller step distance led to more bodily movement during the two-molar distalization. However, displacement tendencies of the first molar and the second molar were basically the same whether horizontal or vertical rectangular attachments were added. Conclusions: A step distance of moving two molars to 0.130 mm can achieve the same reaction force on the anterior teeth as moving one molar 0.250 mm without effects on horizontal or vertical rectangular attachments. Clinical relevance: Our results provide a theoretical basis and guidance for simultaneously moving two molars backward in clinical practice using a clear aligner. [ABSTRACT FROM AUTHOR]

• No difference in sleep quality between the clear aligner and the fixed appliance orthodontic patients. • Orthodontic patients with a high educational level had bad sleep quality. • Female patients tend to have a longer sleep latency. Although available evidence suggests that orthodontic appliances can impact quality of life, there is limited information on the impact of orthodontic appliances on sleep quality. This study aimed to compare sleep quality between patients undergoing orthodontic treatments using conventional fixed appliances and clear aligners. Adult patients attending clinics in Saudi Arabia participated in this cross-sectional study. Sleep quality was assessed using the validated Arabic version of the Pittsburgh Sleep Quality Index (PSQI) and the Epworth Sleepiness Scale (ESS). Statistical significance was determined using inferential analysis, with a P < 0.05 considered statistically significant. There were 69 patients included in the study. The average age of a patient (33.12 ± 8.1) who received the clear aligner was significantly higher than those who received the fixed appliance (27.7 ± 5.9) (P < 0.05). The variation in the average score of ESS because of the education level was found to be statistically significant (P < 0.05). No significant difference was observed between the mean average ESS and PSQI global scores across the two orthodontic treatment groups. The average sleep latency scores were significantly higher in females than males when analyzing the PSQI component score across sex (P < 0.05). In education, ESS, PSQI global, habitual sleep efficiency, the use of sleep medication, and daytime dysfunction had a positive, weak, but significant correlation. Overall, this study concluded that regardless of the orthodontic appliances used, there was no statistically significant difference in sleep quality during the treatment. [ABSTRACT FROM AUTHOR]

Background: During maxillary arch expansion with a clear aligner (CA), buccal tipping of the posterior teeth often occurs, resulting in an unsatisfactory arch expansion effect. The aim of this study was to analyze the appropriate maxillary arch expansion stride length and torque compensation angle for maxillary dentition to achieve an ideal moving state when a CA was used for upper arch expansion. Methods: This study established a three-dimensional (3D) finite element model including a CA, maxilla, periodontal ligament (PDL), and maxillary dentition. The stress distribution, stress situation, expansion efficiency, and movement trends of the maxillary dentition during upper arch expansion of different stride (0.1 mm, 0.2 mm, and 0.3 mm) and torque compensation (0°, 0.5°, 1°, and 1.5°) were measured. Results: Maxillary arch expansion lead to buccal tilt of the posterior teeth, lingual tilt of the anterior teeth, and extrusion of the incisors. As the angle of compensation increased, the degree of buccal tilt on the posterior teeth decreased, with this reducing the efficiency of upper arch expansion. When the stride length was 0.1 mm, the torque compensation was 1.2°, and when stride length was 0.2 mm and the torque compensation was approximately 2°, there was a tendency for the posterior teeth to move bodily. However, when the stride length was 0.3 mm, the increase in torque compensation could not significantly improve the buccal tilt phenomenon. In addition, the equivalent von-Mises stress values of the maxillary root, PDL, and alveolar bone were in the same order of magnitude. Conclusions: This study indicated that the posterior teeth cause a degree of buccal tilt when maxillary arch expansion is ensured. The specific torque compensation angle should be determined based on the patient's situation and the desired effect. [ABSTRACT FROM AUTHOR]

Objectives: In this prospective clinical study, the effect of clear aligners on periodontal health and oral hygiene was examined. As the same time, microbial changes of the aligner tray and subgingival microbiota community were investigated. Methods: The study recruited fifteen patients, and clinical parameters were recorded at three different time points: before the initiation of aligner treatment (T0), 1 month after treatment onset (T1), and 3 months after treatment onset (T3). Plaque samples were collected from the inner surface of aligners and subgingival sulcus at each of these time points. The microbial composition of the samples was analyzed using 16S rRNA gene sequencing, and changes were evaluated based on the abundance of amplicon sequence variants (ASVs). Results: Reduction in plaque index and improvement in periodontal health were observed. In aligner tray plaque samples, the relative abundance of Streptococcus increased significantly, as well as the richness and diversity of microbiota decreased substantially as the duration of treatment time. In subgingival plaque samples, alpha and beta diversity of microbiota did not change significantly. Conclusions: During the clear aligner treatment, the patients' periodontium remained in a healthy condition, and clear aligner treatment had no significant impact on the composition of subgingival microbiota. The structure of the aligner tray microbiota altered significantly at both phylum and genus levels and attracted a unique and less diverse microbiota community. Clabsinabsical relevance: Clear aligner treatment has no significant impact on periodontal health and subgingival microbiota composition of patients. [ABSTRACT FROM AUTHOR]

This article presents the findings of a study on the use of clear aligners for distalizing the mandibular dentition. The study used finite element analysis to compare different methods and sites for total distalization. The results showed that clear aligners primarily cause mesiodistal tipping of individual teeth, with lingual tipping and extrusion of the mandibular anterior teeth being common. The study suggests that selecting the traction site and considering the elastic modulus of the aligners are important factors in achieving desired tooth movements. However, the study had limitations in terms of modeling individual patient diversity and clinical orthodontic force. Further research is needed to address these factors. [Extracted from the article]

The article evaluates bisphenol release from different clear aligner materials using liquid chromatography-mass spectrometry/mass spectrometry. Topics include the types of bisphenols analyzed (Bisphenol A, Bisphenol F, Bisphenol S), the comparison of release among clear aligner brands, and the significance of the findings under the study conditions.

The article compares the efficacy and efficiency of clear aligners (CAT) versus fixed appliances (FAT) in adolescents with moderate to severe malocclusions, finding that CAT cases were completed 3 months faster with eight fewer visits, but treatment efficacy was not significantly different. Topics include treatment outcomes, case attributes, and efficiency measures such as treatment duration, scheduled visits, and emergency visits in adolescents with Class I and II malocclusions.

Objective: The aim of this study is to evaluate the bond strengths of two different composite types used in the production of clear aligner attachments on monolithic zirconia with three different surface roughening processes. Materials and Methods: Packable composite Filtek Z250 was used in one group (PC‐G) and flowable composite Filtek Supreme Ultra Flowable was used in the other group (FC‐G). PC‐G and FC‐G groups were also divided into three subgroups as diamond bur+silane (Group 1), 50 μm aluminium oxide (Al2O3) sandblasting+silane (Group 2) and 110 μm Al2O3 sandblasting+silane (Group 3). Scanning electron microscopy (SEM) analysis was performed. Clear aligner attachments were bonded to the monolithic zirconia specimens. Shear bond strength (SBS) values were measured. Statistical analysis was performed using two‐way ANOVA and post‐hoc Tukey's tests (P <.05). Results: The highest SBS value was found in PC‐G sandblasted with 110 μm Al2O3 (P ≤.001). The etching method with 110 μm sandblasting showed high SBS values in both composite types. The lowest SBS value gave FC‐G in diamond bur roughening (P ≤.001). Conclusions: For the bonding of clear aligner attachments on monolithic zirconia, roughening with 110 μm particle size sandblasting and the choice of packable composite could be recommended in terms of retention. [ABSTRACT FROM AUTHOR]

Objective: To investigate the antibacterial and enamel remineralization performances as well as physicochemical properties and biocompatibility of a fluoride-coated clear aligner plastic (FCAP). Materials and methods: FCAP and normal clear aligner plastic (CAP) was bought from the manufacturer (Angelalign Technology Inc, China). The FCAP was observed under scanning electron microscopy. Its element composition, resistance to separation, contact angle, and protein adhesion performance were characterized. Colony-forming unit (CFU) count and 3-(4,5)-dimethylthiazol(-z-y1)-3,5-diphenyltetrazolium bromide (MTT) assay were used to evaluate the antibacterial ability of Streptococcus mutans. Fluoride release-recharge patterns were obtained. Apatite formation was evaluated after immersing FCAP in artificial saliva. Enamel remineralization capability was evaluated in the demineralization model (immersing samples in demineralization solution for 36 h) and pH cycling model (immersing samples in demineralization solution and remineralization solution in turns for 14 days). Cell Counting Kit-8 (CCK-8) and live/dead cell staining kits were used for cytotoxicity assay. Results: The FCAP showed uniformly distributed fluoride and did not compromise protein adhesion performance. CFU count (5.47 ± 0.55 for CAP, 3.63 ± 0.38 for FCAP) and MTT assay (0.41 ± 0.025 for CAP, 0.28 ± 0.038) indicated that the FCAP had stronger antibacterial activity compared with normal CAP (P < 0.05 for both evaluations). The FCAP could release fluoride continuously for 14 days and could be recharged after immersing in NaF solution. The FCAP could induce the formation of hydroxyapatite in artificial saliva and could reduce the microhardness decrease, color change, and mineral loss of enamels in both two models (P < 0.05 for all evaluations). CCK-8 and live/dead cell staining analyses showed that the coating did not compromise the biocompatibility of the clear aligner (P > 0.05 for CCK-8 evaluation). Conclusions: The FCAP had antibacterial, fluoride recharge, and enamel remineralization abilities while it did not compromise physicochemical properties and biocompatibility. Clinical relevance: The FCAP has the potential to prevent enamel demineralization during clear aligner treatment. [ABSTRACT FROM AUTHOR]