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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]

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. [ABSTRACT FROM AUTHOR]

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. [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 This study aimed to evaluate the biomechanical effects of aligner overtreatment on molar distalization using clear aligners. Methods Various models were created and integrated into finite-element software. Six distinct study models were devised for analysis. The first three models examined second molar distalization with different configurations of attachments, i.e. no attachment, horizontal or vertical attachment on the second molar. For the fourth and fifth models, Class II elastic traction, either implemented via a precision cut or button on canines, was applied. Lastly, aligner overtreatment with varying degrees of root distal tipping (0°, 2°, 4°, 6°, 8°, 10°, and 12°) for the second molar was designed in the last study model. Results Distalization of the second molar produced buccal tipping, distal tipping and intrusion of the second molar, and labial proclination and intrusion of the central incisor. These displacement tendencies were enhanced by adding attachments on the second molar, especially the vertical attachment. Class II elastic tractions enhanced molar distalization and diminish anchorage loss, with the precision-cut configuration being biomechanically superior to the button design. Aligner overtreatment produced bodily molar distalization and mitigated adverse biomechanical effects on anchorage teeth. Limitations The study's limitations include the use of finite-element models, which may not fully represent real clinical scenarios, and the lack of consideration for individual patient variability. Conclusions We suggest that Class II elastic traction via the precision-cut configuration and the design of vertical attachment on the second molar be applied for molar distalization. Appropriate aligner overtreatment helps achieve bodily molar distalization and minimizes adverse biomechanical effects on anchorage teeth. [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]

Objectives: This study aimed to determine the overall oral health statuses of patients with fixed orthodontic appliance and clear aligner, as well as their oral hygiene management behaviours and satisfaction. Methods: We selected 40 participants (20 each with fixed orthodontic devices and clear aligners) who visited a dental clinic. We conducted a survey to determine the oral hygiene management behaviours of the subjects and their satisfaction with their orthodontic treatment. Three measurements were also conducted at 4‐week intervals to determine the oral health statuses of the subjects. Results: The Löe and Silness gingival index of patients with fixed orthodontic appliances indicated moderate gingivitis (1.1 ± 0.3), and those with clear aligners had mild gingivitis (0.6 ± 0.4) (p < 0.001). The modified O'Leary index also indicated that the degree of dental plaque deposition in the oral cavity was lower in patients treated with a clear aligner (43.0 ± 18.2 points) than in those treated with a fixed orthodontic (28.1 ± 10.9 points) (p = 0.004). Regarding oral hygiene management, the fixed orthodontic group received scaling more frequently (p = 0.006), received more oral health education (p < 0.001) and had a longer brushing time (p = 0.008) than the clear aligner group. No significant difference was observed in satisfaction between the fixed orthodontic appliance and the clear aligner. Conclusions: Regarding the oral health status by orthodontic appliance type, the clear aligner group had the advantages of reduction in dental plaque attachment and gingival health. The fixed orthodontic group exhibited better oral hygiene management behaviours. Satisfaction with orthodontic treatment was found to be similar for the two device types. [ABSTRACT FROM AUTHOR]

BACKGROUND: The thin alveolar bone in the lower anterior region increases the risk of labial bone resorption when intruding the teeth with clear aligners. The effect of sagittal overcorrection design on the labiolingual control of mandibular anterior teeth intrusion has not been fully investigated. OBJECTIVE: To explore the effect of overcorrection on the changes in the displacement and stress of the mandibular anterior teeth, especially the cervical and apical regions. METHODS: Through a male volunteer cone-beam CT data, the three-dimensional reconstruction of the mandible and teeth was conducted in the MIMICS and GEOMAGIC software. Moreover, the models of periodontal ligaments, attachments, and appliances were created in the SOLIDWORKS software. First, the study was divided into canine intrusion group and incisor intrusion group. Then, the overcorrection (0°, 1°, 2°) was designed on the bilateral mandibular central and lateral incisors. A total of six models were established. The models were assembled and imported into the ANSYS software to analyze and calculate the displacement and stress level. RESULTS AND CONCLUSION: (1) In the canine intrusion group, canines intruded and tipped lingually while incisors extruded and tipped lingually. In the incisor intrusion group, canines extruded and tipped lingually while incisors intruded and tipped lingually. (2) Without overcorrection, the incisors necks moved lingually while apexes moved labially. With overcorrection, the incisors tended to be upright, followed by labial tilt. The least cervical and apical displacements were detected under 1° overcorrection. (3) With overcorrection, the incisal cervical stress concentration area shifted from labial to lingual in the canine intrusion group, whereas the stress concentration area shifted from lingual to labial in the incisor intrusion group. (4) The incisors tended to tilt lingually when intruding the mandibular anterior teeth with clear aligners. The sagittal overcorrection design was conductive to maintain the stable position of incisors. However, the amount of overcorrection should be moderate. Excessive overcorrection might increase the labial inclination tendencies of incisors. [ABSTRACT FROM AUTHOR]

BACKGROUND: The reciprocal force generated by the molar distalization with clear aligners can lead to anchorage loss. The effect of arch shapes and missing second premolars on anchorage has not been reported. OBJECTIVE: To analyze the effect of arch shapes and missing second premolars on anchorage during molar distalization with clear aligners using the finite element method. METHODS: Cone-beam CT data from an adult male were acquired from the database to establish the maxilla-upper dentition-periodontium-rectangular attachment-clear aligner model. The distal movement amount designed on the bilateral second molars was set to 0.25 mm. First, there were two groups in the study: second premolar bilateral presence and absence groups. Then, four subgroups in each group were created: tapered arch, ovoid arch, square Class II Division 1 arch, and Class II Division 2 arch groups. The Ansys software was used to calculate the displacement of the anchorage tooth and the stress of the periodontal ligament. RESULTS AND CONCLUSION: Mesial tipping and extrusion of first molars and premolars, labial inclination and intrusion of anterior teeth occurred during the upper second molar distalization with clear aligners. When the bilateral second premolars were missing, the mesial displacement of first molars increased significantly while that of first premolars and anterior teeth decreased in all groups. The square Class II Division 1 arch group showed the least anterior labial inclination, while the tapered arch group showed the most. There was no significant difference between the ovoid arch group and the tapered arch group. Moreover, the magnitude of tipping in the square Class II Division 2 arch group was slightly higher than that in the Class II Division 1 arch group. The stress of the periodontal ligament of the anchorage teeth was concentrated on the cervical and apical regions of the teeth. And the lowest stress level was detected in the square arch group. Compared with the other groups, the stress on the labial cervical area of the periodontal ligaments was also significantly relieved in the square arch group. To conclude, the square arch is more favorable in terms of anterior anchorage control and periodontal ligament stress distribution. Anterior labial inclination efficiency can be increased in cases of Class II Division 2 by designing the anterior labial inclination in conjunction with molar distalization. If the second premolar is missing during molar distalization, it is not conducive to opening up the space in the area of the missing tooth. [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]

Abstract 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.

Abstract 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.

Objective: The aim of this study was to evaluate the amount of external apical root resorption in patients who had undergone orthodontic treatment with clear aligners evaluated using cone beam computed tomography. Methods: Studies that evaluated external apical root resorption before and after comprehensive orthodontic treatment with clear aligners were assessed by performing an electronic search from 5 databases comprising PubMed, SCOPUS, EBSCO, Cochrane Library, and LILACS and manual searches in the relevant journals and the reference lists of the included studies. Database search, elimination of duplicate studies, and data extraction were performed independently by 2 authors. The quality of the included studies was assessed using the Risk of Bias in Non-randomised Studies-of Interventions and the Cochrane Collaboration's Risk of Bias Tool. Studies that reported the tooth length or volume were used for quantitative analyses. Results: Nine studies were included in the meta-analysis. The overall root length after clear aligner treatment was significantly decreased compared with the pre-treatment length using cone beam computed tomography (mean differences = −0.56 mm, 95% confidence interval [−0.73, −0.38], P < .00001). However, only the maxillary central incisors, maxillary lateral incisors, and mandibular central incisors had significant reduction in root length. The meta-analysis from 3 studies also indicated that the root volume of the upper incisors also significantly decreased (mean differences = −13.34 mm3, 95% confidence interval [−16.57, −10.10], P < .00001). Conclusions: Current evidence suggests that clear aligners can cause minimal root resorption. The highest amount of root resorption was observed in the maxillary central incisors.

Abstract 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·To reveal the direction, efficiency, and mechanical load of single tooth displacement with clear aligners for expansion treatment during the transitional dentition period with the aid of finite element analysis. Additionally, overcorrection and torque compensation systems were designed to address insufficient expansion efficiency and buccal inclination of posterior teeth.Methods·One volunteer in mixed dentition period was included to construct a three dimentional cranio-maxillary complex model and an invisible orthodontic system, simulating the buccal displacement (load 1‒4: 0.200, 0.275, 0.300, 0.325 mm, respectively) and root buccal torque (load 1: buccal displacement load 0.200 mm, root buccal torque 0°; load 5: buccal displacement load 0.275 mm, root buccal torque 1.0°; load 6: buccal displacement load 0.300 mm, root buccal torque 1.3° and load 7: buccal displacement load 0.325mm, root buccal torque 1.8°) on the maxillary deciduous teeth to the first permanent molar with a non bracket invisible orthodontic appliance. Through finite element analysis, the tooth displacement and equivalent stress distribution of the periodontal membrane can be calculated.Results·Expansion treatment with clear aligners in the transitional dentition phase primarily revealed the effect of buccal expansion of teeth; different teeth achieved different levels of expansion rate. At a set expansion amount of 0.200 mm per side, expansion efficiency in the maxillary first permanent molar was 51.86%, second primary molar 68.76%, first primary molar 73.48%, and primary cuspid 84.17%. By designing over-correction (0.275, 0.300, 0.325 mm), the results showed significant enhancement in expansion effect. When overcorrection length reached 150% (0.300 mm), expansion efficiency at the maxillary first permanent molar, second primary molar, first primary molar, and primary cuspid were 75.16%, 99.96%, 107.35%, and 122.37%, respectively. The expansion efficiency of maxillary second primary molar, first primary molar, and primary cuspid was close to 100.00%. The overcorrection design exacerbated the dental effects of expansion, intensifying the tendency for teeth to tilt toward the cheek side, leading to side effects such as buccal inclination and drooping of the palatal cusps. When the overcorrection amount for expansion reached 150%, the crown-root displacement in the upper first permanent molar, second primary molar, first primary molar, and primary cuspid were -0.109, -0.134, -0.132, and -0.298 mm, respectively. Applying specific torque compensation for different tooth positions can combat the buccal inclination of posterior teeth. At an overcorrection length of 150% (0.300 mm) with an added 1.3° root buccal torque, expansion efficiency was 56.15%, 73.88%, 79.49%, and 87.80%, respectively. While the crown-root displacement differences reduced to -0.081, -0.097, -0.095, and -0.208 mm.Conclusion·When using clear aligners for expansion treatment during a transitional dentition period, side effects such as buccal inclination of posterior teeth exist. Furthermore, various teeth realize differing levels of expansion efficiency, necessitating the design of unique adjustment strategies according to different tooth positions. Overcorrection can improve expansion efficiency but needs to be coordinated with root buccal torque for the whole tooth to move buccally.

Purpose This study investigated the knowledge differences between general practitioners and orthodontists about the Invisalign system.Materials and methods A web-based survey regarding 10 Invisalign treatment domains was distributed to 161 orthodontists and 213 general practitioners. The responses were ranked using a Likert-type scale and analysed with the Chi-square test and Bonferroni adjustment.Results The response rate was 52.1% for general practitioners and 63.4% for orthodontists. Comparing Invisalign to conventional fixed appliances, orthodontists agreed/strongly agreed that Invisalign aligners are suitable for all types of cases (p = 0.001). Orthodontists also agreed that it causes less tooth discomfort (p = 0.01) and an increased number of attachments can affect its esthetic perception (p = 0.014) but general practitioners opted for the ‘Do Not Know’ option (p ≤ 0.01). General practitioners also responded ‘Do Not Know’ to whether Invisalign treatment finishes in a shorter duration (p = 0.001), achieves all types of tooth movement (p

Abstract 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

Abstract 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

Objective To evaluate the clinical efficacy of clear aligner for crowded dentition in early permanent teeth by moving the upper and lower molars far. Methods A total of 36 adolescent patients with Class Ⅰ Angle malocclusion admitted in our department from March 2017 to August 2023 were enrolled, and they were 17 males and 19 females, and at a mean age of 13.20±0.53 years. Clear aligner was applied to push the upper and lower molars backward to obtain a neat dentition. Lateral cephalometric X-ray film before and after treatment was measured, and paired t-test was used to compare the cephalometric measurements before and after treatment. Results The average course of treatment was 21.2 months. Overbite, overjet and molar relationship were turned to normal after treatment, and the soft tissue profile was maintained. Analysis of relevant cephalometric items showed that the Ptm-U6 distance was decreased by 2.89±1.22 mm, and the Go-L6 distance was decreased by 2.61±1.07 mm after treatment, with significant differences (P < 0.01). While, there were no statistically differences in UL-EP, LL-EP, NLA and FCA before and after treatment. Conclusion With reasonable treatment target and good tooth movement design, clear aligner can effectively move the upper and lower molar distally to correct moderate dentition congestion in early permanent teeth, and meanwhile the patients' profile is maintained.

Abstract 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

Abstract 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.

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]

Objective To reveal the direction, efficiency, and mechanical load of single tooth displacement with clear aligners for expansion treatment during the transitional dentition period with the aid of finite element analysis. Additionally, overcorrection and torque compensation systems were designed to address insufficient expansion efficiency and buccal inclination of posterior teeth. Methods •One volunteer in mixed dentition period was included to construct a three dimentional cranio-maxillary complex model and an invisible orthodontic system, simulating the buccal displacement (load 1-4: 0.200, 0.275, 0.300, 0.325 mm, respectively) and root buccal torque (load 1: buccal displacement load 0.200 mm, root buccal torque 0。; load 5: buccal displacement load 0.275 mm, root buccal torque 1.0。; load 6: buccal displacement load 0.300 mm, root buccal torque 1.3。 and load 7: buccal displacement load 0.325mm, root buccal torque 1.8°) on the maxillary deciduous teeth to the first permanent molar with a non bracket invisible orthodontic appliance. Through finite element analysis, the tooth displacement and equivalent stress distribution of the periodontal membrane can be calculated. Results • Expansion treatment with clear aligners in the transitional dentition phase primarily revealed the effect of buccal expansion of teeth; different teeth achieved different levels of expansion rate. At a set expansion amount of 0.200 mm per side, expansion efficiency in the maxillary first permanent molar was 51.86%, second primary molar 68.76%, first primary molar 73.48%, and primary cuspid 84.17%. By designing over-correction (0.275, 0.300, 0.325 mm), the results showed significant enhancement in expansion effect. When overcorrection length reached 150% (0.300 mm), expansion efficiency at the maxillary first permanent molar, second primary molar, first primary molar, and primary cuspid were 75.16%, 99.96%, 107.35%, and 122.37%, respectively. The expansion efficiency of maxillary second primary molar, first primary molar, and primary cuspid was close to 100.00%. The overcorrection design exacerbated the dental effects of expansion, intensifying the tendency for teeth to tilt toward the cheek side, leading to side effects such as buccal inclination and drooping of the palatal cusps. When the overcorrection amount for expansion reached 150%, the crown-root displacement in the upper first permanent molar, second primary molar, first primary molar, and primary cuspid were - 0.109, - 0.134, - 0.132, and 一 0.298 mm, respectively. Applying specific torque compensation for different tooth positions can combat the buccal inclination of posterior teeth. At an overcorrection length of 150% (0.300 mm) with an added 1.3° root buccal torque, expansion efficiency was 56.15%, 73.88%, 79.49%, and 87.80%, respectively. While the crownroot displacement differences reduced to - 0.081, - 0.097, - 0.095, and - 0.208 mm. Conclusion • When using clear aligners for expansion treatment during a transitional dentition period, side effects such as buccal inclination of posterior teeth exist. Furthermore, various teeth realize differing levels of expansion efficiency, necessitating the design of unique adjustment strategies according to different tooth positions. Overcorrection can improve expansion efficiency but needs to be coordinated with root buccal torque for the whole tooth to move buccally. [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]

IntroductionThis study aimed to evaluate the biomechanical effects of different mandibular movements and torque compensations during mandibular advancement with clear aligners using finite element analysis.MethodsModels were constructed to include the mandible, teeth, periodontal ligament (PDL), and clear aligners with buccal wings. Five oral muscles (superficial masseter, deep masseter, medial temporalis, posterior temporalis, and medial pterygoid) were represented as springs. Muscle values were measured and applied during different mandibular movements, including advancement distances (1–7 mm) and occlusal opening distances (2–4 mm). Different torque compensation angles (0°, 1°, 2°, and 3°) were applied to the mandibular central incisor.ResultsWhen the mandibular advancement was equal to or slightly excessed the occlusal opening distance, stress on the posterior PDL decreased and became more evenly distributed. Increasing the occlusal opening distance significantly raised stress on the posterior PDL and caused grater labial inclination of the mandibular anterior teeth. As the torque compensation increased, the labial inclination of the mandibular central incisor decreased, but stress on the PDL increased. Nearly complete bodily movement of the lower central incisor was achieved with torque compensation angles of approximately 15°, 19°, and 20° in models M1-2, M2-3, and M3-4, respectively.ConclusionTo maintain periodontal health during mandibular advancement, it is recommended that the mandibular advancement distance be equal to or slightly excessed the occlusal opening distance. Excessive occlusal opening distance increases stress on the posterior PDL and the labial inclination of mandibular anterior teeth, requiring careful control. Additionally, proper torque control of the mandibular interior teeth is crucial for optimal outcomes.

Objective: The quality of orthodontic forces in aligners is mainly influenced by their mechanical properties. At present, there is insufficient information on how environmental factors affect the mechanical function of aligners, and studies have shown that patients do not pay enough attention to removing aligners while eating and drinking. Therefore, in this study, we investigated the effect of different chemicals on the mechanical properties of thermoplastic materials. Methods: In this study, 175 thermoplastic samples from Easy-Vac gasket (3A Medes, Korea) were prepared, and their chemical composition, tensile strength, and hardness before and after exposure to solutions of orange juice, Cola, chlorhexidine mouthwash, and distilled water were measured. One-Way analysis of variance (ANOVA), Tamhane’s test, and Tukey’s test were used for statistical analysis. Results: The tensile strength of the sheets increased with continuous exposure to orange juice and chlorhexidine mouthwash, and their hardness decreased with continuous exposure to carbonated beverages. There was no change in the chemical composition of the samples after exposure to different chemicals. Conclusion: Although these changes are statistically significant, they do not have a significant effect on the result of aligner performance. Therefore, the only concern is the cariogenicity of orange juice and Cola during treatment with aligners and the administration of chlorhexidine mouthwash.

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

Abstract 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 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 Background We evaluated anxiety, pain, and oral-health-related quality of life in individuals treated with conventional fixed appliances (Group A) and clear aligners (Group B) for moderate malocclusion during the initial phase of orthodontic treatment. Methods Sixty individuals, separated into Group A (n = 30) and Group B (n = 30), were included in the study. They completed the Anxiety Levels, Oral Health Impact Profile-14, and Oral Health Related Quality of Life - United Kingdom/Surveys after the application of attachments on days 0 (T1), 10 (T10), and 20 (T20). Their pain levels were evaluated with the Visual Analogue Scale on days 0, 2, and 6 in the 2nd and 6th hours and on the 1st, 3rd, 7th, 14th, and 21st days. Results Per the VAS questionnaire, pain levels in the 2nd hour, 6th hour, 1st day, and 3rd day were significantly lower in Group B than in Group A. In the OHIP-14 survey results, the comparison between Group A and Group B showed a significant difference only on the 1st day. The STAI and OHRQoL-UK survey results did not differ significantly between the groups. Conclusions We found no significant difference between the two groups in terms of anxiety levels, and pain among individuals in Group A was higher than in Group B only at the beginning of the treatment. No significant differences were observed in terms of individuals’ quality of life. Trial registration NCT06133296 (retrospectively registered)- Registration Date:15/11/2023.

Abstract 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 0.05).

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, inter-proximal 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=0.05). Pretreatment and posttreatment mean differences in alveolar bone defects were statistically significant across all the studied variables (p

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]

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]