{"paper_id":"159885fb-c1e8-41a8-bc64-e28ec7c2a324","body_text":"Improving Facial Crown Tipping with Clear Aligners: the role of attachment design and composite flash | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Improving Facial Crown Tipping with Clear Aligners: the role of attachment design and composite flash Pascal Vollenweider, Flavio Traversa, James Mah, Michael de Wild, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9517209/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 7 You are reading this latest preprint version Abstract Purpose To evaluate how attachment geometry, vertical positioning, and composite flash influence the biomechanics of facial crown tipping in clear aligner therapy (CAT). Methods Seven attachment configurations were tested on the Orthodontic Force Simulator (OFS): No attachment (NoAt), vertical rectangular attachment including central (recV), with flash (recVf), and occlusally shifted with flash (recVfs) as well as beveled designs with central (bevC), occlusal (bevO), and gingival (bevG) positioning. Thirty-five ClearQuartz™ aligners were thermoformed and loaded under a 3° facial tipping protocol. The primary outcome was the movement efficiency (ME, facial crown torque divided by facial force). Force and torque data are reported in addition for a better understanding of the side effects created by the designs. The normality of the data was analyzed with the Shapiro-Wilk and the Kolmogorov–Smirnov test, and the Mann–Whitney U test was applied due to non-normality. Results All designs tested revealed significant different movement efficiencies. The beveled attachment placed close to the gingival margin generated the highest median absolute ME (-4.45 and − 4.51) as well as the highest facial crown torque (39.6 N, 40.2 N) for both test rounds. All attachment designs with attachments showed a higher ME compared to the crown design without any attachment except recVfs (recVfs: -1.58, -1.73; NoAt: -1.88, -1.89). Conclusions Attachment geometry, vertical displacement, and composite flash significantly influence aligner biomechanics. Placing an attachment as close as possible to the center of resistance as well as ensure its proper shape and position increase movement efficiency. Orthodontic Appliances Removable Introduction Clear aligner therapy (CAT) has become a widely adopted alternative to conventional fixed appliances, particularly among adult patients seeking aesthetic and minimally invasive treatment. Driven by advances in digital workflows and material science, its global adoption continues to grow. Malocclusions affect approximately 56% of the global population (Lombardo et al. 2020 ). In Australia, 24.17% of orthodontic cases are managed exclusively with clear aligners (Meade and Weir 2022 ). This trend is further confirmed by GAiDGE’s 2023 annual report showing about one third of all orthodontic treatments are started with clear aligners (GAiDGE 360 Consulting 2023 ). The digitalization of orthodontics has allowed for fully digital workflows, which include intraoral scanning, computer-aided design (CAD), and 3D printing. CAD/computer-aided manufacturing (CAM) technologies enable the customization of aligners and auxiliaries such as attachments (added composite material on clinical crown), whose geometry and positioning can be defined digitally before clinical application. Additionally, modern aligners are manufactured from multi-layer thermoplastic polymers designed to optimize force delivery and reduce stress relaxation.(Bichu et al. 2023 ) Despite technological advances, achieving precise and predictable dental movements remains consistently challenging.(Castroflorio et al. 2023 ) Crown tipping, although reported as one of the easiest movements in CAT (difficulty classification 1.79 ± 1.35 on a 6-point scale)(Abu-Arqub et al. 2023 ), shows low clinical precision between planned and executed movements, with reported predictability for faciolingual inclination as low as 56% (Haouili et al. 2020 ). The maxillary lateral incisor in turn was mentioned as frequently problematic in CAT by 21 independent orthodontists.(Meade and Weir 2022 ) Composite attachments are standard auxiliaries in CAT; their shape and positioning affect both aligner retention and the expression of force on the clinical crown.(Jedliński et al. 2023 ) Jedliński et al. ( 2023 ) reviewed 22 publications on the influence of attachments on movement efficacy, but none of them specifically looked into the effects of excessive material, often remaining on the clinical crown after bonding, on the ME. Jones et al. ( 2009 ) reported a higher retention force for gingivally placed attachments compared to occlusally placed attachments (rectangular and beveled shape). In their discussion, they identify the lack of clinical evidence for the correlation between highly retentive aligners and efficiency of the aligner treatment. Improperly designed or placed attachments may lead to inefficient force distribution or unintended loading on adjacent teeth and excessive composite material (“flash”) prevent complete aligner seating, compromise fit and pressure distribution and reduce movement predictability.(Larson 2022 ; Kiong et al. 2024 ) Comparing different composite materials used for bonding attachments, a gel-like composite (Filtek Z350 XT universal) was found to be less prone to flash generation, staining and debonding compared to flowable composites (Z350 XT flowable).(Erbas and Atik 2025 ) To achieve a controlled facial tipping, the faciolingual torque (CT facial ) is the primary biomechanical driver. The clinical goal is to maximize this torque while avoiding undesired side effects in the form of unplanned forces and torques. Faciolingual (F fl ), mesiodistal (F md ), and apico-occlusal (F ao ) forces as well as their associated mesiodistal, faciolingual, and mesiolingual/distolingual torque contribute to unintended movements such as distal drift, vertical intrusion/extrusion, or unwanted rotations. These components also act on adjacent teeth or destabilize the targeted tooth’s movement, thereby increasing the likelihood of refinement. Previous investigations on clear aligner auxiliaries have examined either attachment geometry or position in isolation, often using finite element models of central incisors or molars and focusing on translational movements or extrusion rather than crown tipping.(Hong et al. 2021 ; Alhasyimi et al. 2024 ; Magura et al. 2025 ; Choi et al. 2025 ) Root torque of a central incisor was investigated in-vitro comparing ellipsoidal and rectangular attachments at different vertical positions using an orthodontic force tester (Magura et al. 2025 ). The vertical position of the attachment was shown to significantly influence the forces and moments generated on the tooth with the central third and ellipsoid design being the most favorable. Recent in-vitro studies on composite flash have demonstrated that flash increases unwanted forces, but they typically evaluated a single attachment type on isolated teeth and did not explore how flash interacts with attachment position in a full-arch biomechanical system.(Larson 2022 ; Kiong et al. 2024 ) Kiong et al. ( 2024 ) used a pressure foil to visualize the pressure on the crown generated by different attachment configurations including flash, however, the study design fails to quantify the effective forces generated at the center of resistance. To date, there is no experimental 6 degrees of freedom analysis quantifying the combined effects of attachment geometry, vertical positioning, and composite flash on facial crown tipping of the maxillary lateral incisor, a tooth that displays low predictability in clear aligner therapy (Charalampakis et al. 2018 ) and is frequently identified by clinicians as problematic.(Meade and Weir 2022 ) Therefore, this in-vitro study aimed to (1) compare rectangular and beveled attachment designs at different vertical positions, (2) evaluate the impact of composite flash and deliberate vertical misplacement on the ME (CT facial / F fl ), and (3) characterize how these modifications alter load transmission to adjacent teeth in a full maxillary arch. All these investigations were investigated on the maxillary lateral incisor while additionally reporting the loadings experienced by the closest neighbors. Material and Methods Experimental Setup A mechanical in vitro analysis was conducted using the Orthodontic Force Simulator (OFS; Institut Straumann, Basel, Switzerland) to evaluate seven attachment configurations on the maxillary right lateral incisor. Each design was tested using five identical thermoformed aligners manufactured from 0.762 mm ClearQuartz™ sheets (ClearCorrect®, Basel, Switzerland), totaling 35 aligners. The analysis focused on the force and torque systems generated during a simulated 3° lingual crown angulation movement, with the ME (CT facial /F fl ) as the primary outcome reflecting the purity of the tipping movement. Orthodontic Force Simulator and measured variables The OFS employed the same advanced in-vitro testing apparatus described in previous studies, comprising both hardware and software components (LabVIEW 2022 Q3 Full, Austin, US).(Traversa and Mah 2023 ) The setup included a dentition model symmetric to the sagittal plane, with each tooth mounted on a 6-channel force and torque sensor (MMS101, MinebeaMitsumi Inc., Tokyo, Japan) (See Fig. 1 ). Six variables were recorded for each tooth: facio-lingual (F fl ), mesio-distal (F md ), and apico-occlusal (F ao ) forces, as well as the corresponding torques (CT facial , CT md , R mldl ). Table 1 Positive direction for the lateral incisor Variable Positive direction F fl lingual F md distal F ao occlusal CT facial facial CT md distal R mldl disto-lingual Positive directions for the six variables are listed in Table 1 , also indicated visually in Fig. 1 by the direction of the arrows displayed. The right lateral incisor was mounted on a six-axis hexapod (H-811.I2, Physik Instrumente (PI) GmbH & Co. KG, Germany), allowing translations and rotations in all six degrees of freedom during the experiment. An individual transformation matrix was applied for each tooth to transfer the measured loadings at the sensor to the tooth’s center of resistance (CoR), which was defined based on established literature.(Geiger and Lapatki 2014 ) Despite six degrees of freedom were measured for all 14 teeth of the simulated maxillary arch, only the facial crown torque (CT facial ) and the facio-lingual force (F fl ) of the lateral incisor were further considered for the ME. CT facial is the primary driver of the planned facial crown tipping and F fl is the expected largest side effect. Clear Aligner Fabrication The OFS dentition was scanned in a neutral position using an intraoral scanner (Virtuo Vivo, Straumann, Basel, Switzerland). The scan data were then virtually superimposed with the original gingiva. The interproximal spaces were filled with small wedge-shaped geometries (see Fig. 1 c). Before 3D printing, the models were scaled to 100.4% to compensate for shrinkage effects during the production workflow.(Schwarzmann 2019 ) The generated models were then 3D printed using VeroWhite resin with an Objet260 printer (Stratasys, Rehovot, Israel), and the support material was manually removed using a water jet machine. This procedure was repeated for each of the different designs. One 3D model was printed for each design, and five aligners were thermoformed with each, resulting in a total of seven models and 35 aligners. ClearQuartz sheets with a thickness of 0.76 mm (ClearCorrect, Basel, Switzerland) were thermoformed at a pressure of 6 bars using a Drufomat thermoforming machine (Dreve Dentamid GmbH, Unna, Germany). ClearQuartz is a 3-layer material containing thermoplastic urethane, known for its low stress relaxation rate and low initial forces.(Lombardo et al. 2017 ; Straumann Group 2025 ) To ease separation of the thermoformed sheet from the 3D printed arch model, a separation liquid (Aqualease™ 75, Mann release technologies™, Macungie, Pennsylvania, USA) was used. After thermoforming, the sheets were separated from the 3D printed arch model, and a flat trimline 2 mm above the gingival margin was cut using a laser cutting machine (LAC, DMU - Dental Manufacturing Unit GmbH, Puch bei Hallein, Austria). The extended flat trimline was selected for its superior retention and enhanced control of tooth movement.(Elshazly et al. 2024 ) All aligners were produced based on the neutral dentition scan, meaning the printed arch models used for thermoforming did not have any tooth movements programmed. After manufacturing, aligners were cleaned with dishwasher soap and water to remove the remaining separation liquid and stored in testing environment under ambient conditions for 48 hours prior testing. Testing Procedures All measurements performed on the OFS were conducted at room temperature (21 ± 1°C). The aligners were moisturized with distilled water on the contact surface prior to insertion on the OFS dentition. The right lateral incisor, mounted on the hexapod, was 3° lingually tipped (rotation around its CoR) to simulate a planned facial crown tipping scenario from the aligner perspective. This procedure reflects a clinically realistic scenario of facial tipping where the aligner has 3° facial tipping programmed and the lateral incisor is 3° more lingual than programmed in the aligner shape. To isolate the effects on the arch, no movement was programmed in the rest of the arch. After the 3° lingual deflection of the lateral incisor, the aligner was inserted on the dentition within 5 seconds. Subsequently, a 10-second measurement period was further used for all six degrees of freedom. Each of the five aligners per design was tested twice, resulting in 10 measurements per crown design and a total of 70 measurements. The aligners rested for at least 5 minutes between the testing rounds. Attachment (Crown) Designs The lateral incisor used in this study has a maximal crown width of 6.5 mm and a total length of 20.5 mm, where the CoR is located 6.3 mm towards occlusal from the apical point of the root. The crown length from the incisal edge to the cervical point is 8.7 mm and thus the root length 11.8 mm. Seven different attachment designs were evaluated in this study and are summarized in Table 2 . The control design (NoAt) represents the bare crown without any attachments. The recV design simulates a perfect vertical rectangular attachment, while recVf represents a vertical rectangular attachment with added flash. The recVfs design features a vertically oriented rectangular geometry with added flash and is shifted 1 mm toward the incisal edge. The 1 mm shift was selected based on practical usability verification with clinical users, comparing the achieved attachment position to the planned digital position. Achieved positions were captured with an intraoral scanner (Virtuo Vivo, Straumann, Basel, Switzerland) and assessed against the corresponding digital reference. The beveled designs (bevC, bevO, bevG) represent beveled attachments positioned at three different vertical positions. The 2 mm apical displacement was selected as it represents the maximum possible shift from the center towards the gingival margin while maintaining a safe distance from the gingiva in the dentition model. This ensures that the attachment could be bonded at this position in a clinical setting without the risk of damaging the gingiva. Additionally, thermoforming shows limitations in adaptability in areas of small slits or holes, which is why the gap between the gingiva and the attachment must be large enough to allow proper thermoforming adaptation. The incisal shift was also set to 2 mm due to consistency. Both, the rectangular and the beveled attachment shape are commercially available designs, distributed by ClearCorrect (Straumann Group, Basel, Switzerland). All aligners were manufactured based on the designs described above, except for recVf and recVfs. To reflect the clinical situation, the aligners for these two designs were manufactured based on recV, creating a deliberate mismatch between the aligner and the dentition, simulating clinical scenarios of flash and mispositioning. Statistical Analysis The primary outcome of the designs tested is their ME. The ME for facial crown tipping is defined as the torque generating the crown tipping (CT facial ) divided by the expected largest side effect (F fl ). ME (ME): ME (ME): \\(\\:\\frac{{CT}_{facial}}{{F}_{fl}}\\) Due to the setup design, a facial crown torque is defined in positive direction, and a facial force is defined in negative direction, which creates negative efficiency values for all designs a facial force is present. For the assessment of the ME, only the magnitude of the ME is relevant, the sign can therefore be ignored but is not removed due to originality of the data. The higher the absolute value of ME, the more precise the movement is assumed to happen clinically. The following hypothesis shall be tested regarding significant differences: Composite flash and position H1.1: Composite flash around the attachment (recVf) shows a significant lower ME compared to an optimal attachment design (recV). H1.2: Composite flash and a vertical shift (recVfs) show a significant lower ME compared to an optimal attachment design (recV). Attachment shape H2.1a: The presence of a centrally placed rectangular attachment (recV) significantly increases ME compared to no attachment (NoAt). H2.1b: The presence of a centrally placed beveled attachment (bevC) significantly increases ME compared to no attachment (NoAt). H2.2: The beveled (bevC) and rectangular attachment (recV) show no significant difference in ME when centrally placed on the crown. Vertical position H3.1: The beveled attachment placed more gingival (bevG) shows significant higher ME compared to centrally placed (bevC). H3.2:The beveled attachment placed more occlusal (bevO) shows significant lower ME compared to centrally placed (bevC). Statistical analyses were performed in R (RStudio, version 4.3.1) using a reproducible RMarkdown workflow. The raw data from the Orthodontic Force Simulator (OFS) containing 3 force and 3 torque measurements together with a time stamp for each tooth were converted to an Excel spreadsheet. Only values for the lateral incisor are reported here, except for Fig. 3 , where the loading experienced by adjacent teeth is also visualized. The Excel files were imported via the readxl package, and numeric variables were converted from European decimal format (comma as decimal separator) to standard numeric format. Data processing and grouping were handled with dplyr, and graphical assessments were performed using ggplot2. Normality within each study group and measurement repetition (7 study groups, 2 measurement repetitions) was evaluated using the Shapiro-Wilk test and the Kolmogorov-Smirnov test with Lilliefors correction (nortest package). Complementary quantile-quantile (QQ) plots were generated for visual inspection of the distributional assumptions. All normality tests yielded highly significant p-values, and the corresponding QQ-plots clearly indicated deviations from normal distribution in all subgroups. Therefore, subsequent analyses were performed using non-parametric statistical methods. Comparative analyses of ME (CT facial / F fl ) were performed across study groups to test the above-mentioned hypothesis regarding the effect of different attachment designs and placements. Due to the lack of normal distribution in all subgroups (assessed by Shapiro-Wilk and Kolmogorov-Smirnov tests with Lilliefors correction), non-parametric statistical methods were applied. For each hypothesis, the Mann-Whitney U test (wilcox.test in R) was used to compare the ME between the two designs and their test rounds. Since each aligner was measured twice, tests were performed separately for each repetition (Repetition 1 and Repetition 2). Boxplots were generated (see Online Resource 1) to visualize the distribution of ME across cases and repetitions. Results Movement Efficiency (ME) The raw data measurements for the facial crown torque of the lateral incisor with no attachment (NoAt) are visualized in Fig. 2 . The first 5 seconds are cut due to manual insertion, measurements between 5 and 15 seconds are used for further analysis. This kind of raw data cut was performed for all 7 crown designs and their corresponding force and torque measurements. The normality of each data section was assessed using the Shapiro-Wilk test and the Kolmogorov-Smirnov test with Lilliefors correction as well as QQ-plots for visual inspection. Since all tests showed significant differences from a normal distribution for all sections, the Wilcoxon rank sum test with continuity correction was applied to test significant different (α = 0.05) MEs between designs. Table 3 ME of tested Designs (Median, IQR) Movement Efficiency (CT facial / F fl ) Repetition 1 Repetition 2 Median IQR Median IQR NoAt -1.88 [-1.92, -1.83] -1.89 [-1.91, -1.72] recV -4.06 [-4.13, -3.86] -4.01 [-4.12, -3.96] recVf -2.50 [-2.55, -2.48] -2.46 [-2.49, -2.44] recVfs -1.58 [-1.66, -1.42] -1.73 [-1.8, -1.64] bevC -3.56 [-3.69, -3.5] -3.76 [-3.79, -3.71] bevO -3.15 [-3.21, -3.1] -3.15 [-3.17–2.95] bevG -4.45 [-4.58, -4.42] -4.51 [-4.54, -4.42] The median ME values along with their interquartile ranges (IQR) are listed in Table 3 . Since all measurements showed a facial force (negative sensor reading) and a facial crown torque (positive sensor reading), all ME values are negative. As mentioned in the methods section, the higher the absolute value of the ME, the more precise the movement is expected to happen clinically. For further interpretation, descriptions about ME values only consider their magnitude. Based on the results shown, the beveled attachment design 2 mm shifted towards the gingival margin shows the highest ME (bevG, Median: -4.45, -4.51) where the rectangular attachments with added flash and 1 mm occlusal shift revealed the lowest ME (recVfs, Median: -1.58, -1.73). Table 4 Hypothesis Tests based on Wilcoxon rank sum test Hypothesis Design Comparison p-value Decision Superior Design H1.1 recV recVf < 0.001 confirmed recV H1.2 recV recVfs < 0.001 confirmed recV H2.1a NoAt recV < 0.001 confirmed recV H2.1b NoAt bevC < 0.001 confirmed bevC H2.2 recV bevC < 0.001 rejected recV H3.1 bevC bevG < 0.001 confirmed bevG H3.2 bevC bevO < 0.001 confirmed bevC Table 4 shows the results comparing the designs based on the different initial hypotheses built. All hypotheses can be accepted except H2.2, where a non-significant difference in ME was expected between the two attachment shapes tested. Corresponding boxplots for each hypothesis can be found in the supplementary material. Loading Situation Where the ME is the primary outcome of this study, the force and torque values of the designs tested are still reported in Table 5 due to the more detailed insights they provide regarding side effects. Table 5 Median [IQR] values of forces and torques measured for the lateral incisor of all designs for each test round (R1, R2) Rep. NoAt recV recVf recVfs bevC bevO bevG F fl [N] 1 -16.1 [-16.3, -15.9] -6.4 [-6.8, -6.1] -10.4 [-11.2, -9.6] -6.2 [-6.4, -5.6] -8.3 [-9.1, -7.5] -11.6 [-12.2, -9.3] -8.9 [-9.9, -8.8] 2 -15.9 [-16.0, -14.8] -6.4 [-7.0, -6.2] -11.0 [-11.4, -10.4] -5.9 [-5.9, -5.6] -9.7 [-9.8, -9.3] -10.6 [-12.5, -9.9] -8.9 [-10.1, -8.6] F md [N] 1 0.5 [-0.3, 0.6] 0.0 [-0.2, 0.3] -1.4 [-1.6, -0.4] 2.1 [2.0, 2.4] -1.1 [-1.8, -1.1] -0.6 [-0.6, -0.3] -3.3 [-3.7, -3.3] 2 0.5 [-1.1, 0.7] -0.5 [-0.6, -0.4] -1.2 [-1.3, -1.1] 1.7 [1.7, 2.2] -1.7 [-2.2, -1.6] -0.3 [-0.7, -0.1] -3.7 [-3.9, -3.2] F ao [N] 1 1.1 [1.0, 1.2] 4.7 [4.0, 5.1] 2.3 [2.3, 3.3] -3.4 [-3.5, -2.7] 4.8 [4.7, 5.7] 8.1 [5.8, 8.4] 5.7 [5.6, 6.5] 2 1.3 [0.7, 1.6] 4.3 [4.1, 4.9] 2.4 [2.4, 3.2] -2.8 [-3.0, -2.8] 5.8 [5.5, 7.7] 8.2 [7.1, 8.5] 5.9 [5.5, 6.8] CT facial [Ncm] 1 31.2 [29.2, 31.2] 26.2 [23.6, 28.0] 26.1 [24.5, 28.6] 9.4 [8.9, 10.2] 27.9 [26.5, 30.6] 35.9 [29.0, 39.1] 39.6 [38.7, 45.4] 2 27.7 [27.2, 30.4] 25.8 [23.3, 28.7] 28.0 [25.1, 28.0] 9.8 [8.8, 10.8] 35.1 [34.4, 36.2] 33.4 [29.2, 35.8] 40.2 [37.7, 46.0] CT md [Ncm] 1 13.7 [13.3, 14.2] 1.2 [0.5, 1.7] 2.8 [2.5, 4.3] -1.5 [-1.6, -0.5] 11.3 [11.1, 11.3] 7.0 [6.9, 7.3] 10.8 [10.5, 12.8] 2 12.2 [8.4, 13.9] 0.1 [0.1, 0.2] 2.8 [2.7, 3.8] -1.6 [-1.8, -1.5] 12.2 [12.2, 12.6] 5.9 [4.6, 6.2] 11.6 [10.3, 13.0] R mldl [Ncm] 1 7.4 [7.1, 7.6] 0.0 [-0.4, 0.1] 1.3 [1.3, 1.8] -1.7 [-1.7, -1.5] 5.2 [4.9, 5.4] 4.1 [3.9, 4.4] 6.7 [6.1, 7.6] 2 7.0 [6.1, 7.6] -0.5 [-0.5, -0.3] 1.6 [1.4, 2.0] -1.7 [-1.9, -1.5] 6.0 [5.8, 6.5] 3.1 [2.9, 4.1] 6.5 [6.2, 7.8] The bevG showed the highest ME among all designs tested, it also shows the highest facial crown torque (CT facial ) among the designs (39.6 and 40.2 Ncm). Regarding the largest side effect F fl , bevG shows lower magnitudes compared to NoAt, recVf, and bevO. Only recV was able to further reduce the side effects of facial force. Although recVfs shows low magnitudes for F fl as well, CT facial below 10 N is more than 60% lower compared to all other designs which results in a low ME, shown in Table 2 . Effects on adjacent teeth The lateral incisor was not the sole recipient of forces and torques; the adjacent teeth also experienced loadings transmitted through the aligner. These neighboring teeth act as anchorage. In most cases, the force and torque equilibrium theory was shown by counterforces in the canine and the central incisor (see Fig. 3 ). Discussion This study investigated how attachment geometry, vertical position, and composite flash influence the force system generated during facial crown tipping of the maxillary lateral incisor with clear aligners. Among the tested configurations, the gingivally positioned beveled attachment (bevG) produced the highest absolute ME, whereas the rectangular attachment shifted occlusally to mimic a non-fitting aligner (recVfs) showed the lowest ME. Because load transfer in clear aligner mechanics is concentrated at the aligner-attachment contact region (Hong et al. 2021 ), the vertical position of the attachment is expected to affect the resulting force system relative to the tooth’s center of resistance (CoR). Positioning the attachment closer to the estimated center of resistance reduces the effective moment arm of the dominant contact force and may therefore reduce parasitic force components and unintended side effects, while improving the efficiency of the intended tipping response. Although crown pressure distribution was not quantified in this study, the observed differences between bevG and recVfs are consistent with the concept that force application closer to the center of resistance improves ME for facial crown tipping. Indeed, force application at or near CoR is desirable from a clinical efficiency and predictability perspective with this being a goal of orthodontic appliance designs. The addition of composite flash (recVf) decreased the ME compared to the optimal design (recV), underlining the importance of properly placed attachments including the removal of excessive material (Median ME for recV: -4.06 / -4.01 compared to recVf: 2.50 / 2.46). Although, excessive material may be considered as an unavoidable consequence of chairside attachment fabrication, the long term impact on clinical efficiency may be significant. The time and effort to achieve a proper attachment would be a key step towards aligner performance. Within the context of previous work on clear aligner biomechanics, this investigation provides three main contributions. First, it offers an experimental six-degree-of-freedom analysis of facial crown tipping in a maxillary lateral incisor, whereas most prior studies focused on translational movements, primarily in central incisors and molars.(Traversa and Mah 2023 ; Bojrab et al. 2024 ; Alhasyimi et al. 2024 ; Traversa et al. 2025 ; Magura et al. 2025 ; Choi et al. 2025 ) Second, it systematically combines attachment geometry, vertical position, and composite flash, including a clinically realistic non-fitting scenario, within one standardized setup, allowing direct comparison of the resulting movement efficiencies. Third, it reports all six degrees of freedom measured in two sequential test runs enabling the analysis of side effects in more detail. These types of studies are very much lacking as it integrates real-world clinical aspects that impact aligner force application and ultimately performance and efficiency. From a biomechanical perspective, the rectangular attachment placed centrally (recV) reduced facial force by approximately 60% compared with the NoAt configuration while losing only 16% or less of facial crown torque (CT facial ). The centrally placed rectangular attachment yielded a favorable ME (-4.06 and − 4.01), which can be associated with improved rotational control during tipping movements. The gingivally positioned beveled attachment (bevG) generated the highest facial crown torque (39.6 and 40.2 Ncm) and the most favorable ME (-4.58 and − 4.42) among all designs. Jones et al. (Jones et al. 2009 ) reported the highest retention for gingivally placed beveled attachments, suggesting that the improved retention may contribute to increased force magnitude due to a tighter aligner fit. A plausible explanation is that the gingivally positioned bevel creates an undercut that enhances aligner retention and force transmission during seating. To the best of our knowledge, this is the first evidence connecting vertical aligner retention and force expression on a single crown, indicating that superior vertical retention may lead to better force expression and therefore more controlled movement. Although the present study is an in-vitro study, it still contributes to the need formulated by Jones et al. (Jones et al. 2009 ). In the present setup, the gap between the gingiva and the attachment appeared sufficient to allow adequate adaptation during thermoforming. However, it is expected that a minimal distance between the ginigva and the attachment must be maintained to allow sufficient aligner adaptation creating a functional attachment. Further studies are needed to confirm whether the mechanical advantage observed here translates directly into improved clinical performance. Composite flash (recVf) did not change the facial crown torque compared to the optimal attachment shape (recV) but led to a marked increase in facial force (F fl ). Mechanically, flash acts as an irregular spacer that disrupts intimate contact between the aligner, the crown surface and the attachment, redistributing contact pressure and amplifying unwanted translational components. This observation is consistent with finite element analysis showing that flash can alter the intended force system and reduce the predictability of tooth movement.(Larson 2022 ) In the present study, the absolute facial force increased by more than 60% when flash was present, supporting previous work suggesting that even minimal flash can substantially intensify side effects.(Larson 2022 ) Vertical displacement of the attachment, creating a non-fitting aligner (recVfs), also had a pronounced impact on the ME and force system. Occlusally shifting the rectangular attachment resulted in a marked reduction of the facial crown torque, confirming that accurate aligner-attachment fit is essential for predictable tooth movements. Notably, the non-fitting design (recVfs) was the only one tested showing a lower ME in both test runs compared to the design with no attachment (NoAt). Thus, both attachment positioning and the absence of flash are critical to maintaining a high ME and minimizing side effects. Adding the information of the forces experienced by the adjacent teeth, it can be seen that most of the counter-forces are emitted by the direct neighbors. In consequence, even if only one tooth has a programmed facial tipping of 3°, the adjacent teeth are likely to move in the opposite direction. This finding presents the evidence of how complex tooth movements are, especially when they are planned simultaneously. Side effects can potentially be transferred to the full arch making it hard to predict any forces generated on the single tooth. Therefore, an experimental machine such as the OFS is crucial in understanding the interaction between different prescribed tooth movements, especially in combination with auxiliaries such as attachments. The present findings align with and expand previous clinical and experimental data. Jedliński et al. ( 2023 ) reported improved orthodontic tooth movement when using attachments; this is supported here by the significant reduction in facial force, mesiodistal torque, and axial rotation observed with the recV design compared with no attachment. Based on the results of this study, a gingivally positioned beveled attachment appears most suitable for facial tipping of maxillary lateral incisors, providing an optimal balance between tipping efficacy and control of side effects. In contrast, poorly positioned attachments or those with composite flash may reduce ME by more than 60% (CT facial /F fl for bevG: -4.45 and − 4.51 compared to recVfs: -1.58 and − 1.73). While use of attachments may be a routine practice, particulary for specific tooth movements, their accurate production and placement are directly linked to aligner performance and the resultant tooth movements. Poorly made and placed attachments may increase the need for refinements, and compromise aligner fit, and potentially contribute to attachment debonding or loss of movement control. Clinicians are therefore encouraged to employ attachment bonding templates designed to limit flash, verify bonding intraorally and, if necessary, clean excessive composite material. Jedliński et al. ( 2023 ) further reported that flowable composites or orthodontic bonding composites provide the highest attachment accuracy and durability, which may help clinicians achieve the full biomechanical potential of the prescribed attachment design. The applied methodology has certain limitations which affects the direct translation of the results obtained in this study into a clinical setting. First, the aligners were tested at room temperature where the intraoral temperature is around 37°C. Second, the Orthodontic Force Simulator is very rigidly designed aiming for high reproducibility, which does not allow the presence of a periodontal ligament (PDL). Additionally, no saliva was present and bone remodelling was not simulated. The higher temperature as well as the presence of the PDL are expected to lower the force magnitude but not the ME of the designs tested, thus the same mechanisms observed in vitro are expected in a clinical setting. The use of the Orthodontic Force Simulator enabled comprehensive vectorial measurement with high reproducibility. The protocol also standardized measurements at 10 seconds to account for viscoelastic relaxation, reflecting the early clinical phase after aligner seating. Where the aligner will relax over time, it is expected that only the force magnitude, but not the ME, will change. Future research should extend this approach to more complex, clinically applied movement patterns and additional tooth types. In practice, planned movements often involve combined translations and rotations, where the management of unwanted side effects becomes even more critical for achieving high movement efficiency. Evaluating different attachment designs and bonding strategies under such combined loading conditions would further bridge the gap between experimental biomechanics and clinical outcomes. Conclusions Within the limitations of the orthodontic force simulator setup, gingivally positioned beveled attachments generated the most favorable balance between facial crown torque and its side effects. These mechanical findings suggest that precise attachment placement and flash-free bonding may improve the predictability of facial crown tipping and merit prospective clinical evaluation. Key biomechanical findings indicate that: Attachments placed as close as possible to the center of resistance increase movement efficiency. Leaving flash to attachment bases after bonding increases unwanted side effects and leads to less precise OTM. A vertical mismatch of 1.0 mm between attachment and attachment void in the aligner reduced facial crown torque by more than 60% compared to an optimally placed and shaped attachment. Force transmission patterns across the dental arch are significantly influenced by attachment positioning, potentially causing undesired effects in adjacent teeth. Abbreviations OFS Orthodontic Force Simulator IQR Interquartile range OTM Orthodontic tooth movement CAT Clear aligner treatment CoR Center of resistance ME Movement efficiency PDL Periodontal ligament Declarations Acknowledgements We would like to thank Roger Voegtlin for his contributions to this research. As the producer of the custom crown designs, Roger's expertise and meticulous craftsmanship were pivotal in enabling the seamless testing of the different tooth designs. Statements and Declarations The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Funding The materials used in this study were provided by Institut Straumann AG. Financial Interests Pascal Vollenweider: Employee at Institut Straumann AG. Flavio Traversa: Employee at Institut Straumann AG. James Mah: Paid expert testimony. Michael de Wild: None Philippe Chavanne: None Alain Hedinger: Employee at Institut Straumann AG. Author contributions PV: Conceptualization, data curation, formal analysis, investigation, methodology, software, visualization, writing – original draft, writing – review and editing FT: Methodology JM: Supervision, writing – review and editing MdW: Supervision PC: Project administration, supervision AH: Resources Ethics approval and consent to participate Not applicable. Consent for publication Not applicable. Availability of data All data supporting the findings of this study are available within the paper. Funding The used materials were funded by Institut Straumann AG, Switzerland. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Declaration of generative AI and AI-assisted technologies in the writing process During the preparation of this work the author used ChatGPT to enhance language clarity and style. After using ChatGPT, the author reviewed and edited the content as needed and takes full responsibility for the content of the published article. References Abu-Arqub S, Ahmida A, Da Cunha Godoy L, et al (2023) Insight into clear aligner therapy protocols and preferences among members of the American Association of Orthodontists in the United States and Canada. Angle Orthod 93:417–426. https://doi.org/10.2319/101022-694.1 Alhasyimi AA, Ayub A, Farmasyanti CA (2024) Effectiveness of the Attachment Design and Thickness of Clear Aligners during Orthodontic Anterior Retraction: Finite Element Analysis. Eur J Dent 18:174–181. https://doi.org/10.1055/s-0043-1761452 Bichu YM, Alwafi A, Liu X, et al (2023) Advances in orthodontic clear aligner materials. Bioact Mater 22:384–403. https://doi.org/10.1016/j.bioactmat.2022.10.006 Bojrab A, Akbari A, Broyles D, et al (2024) In Vitro Comparison of the Effectiveness of Different Attachment Shapes and Locations on Extrusion of the Upper Left Lateral Incisor Using Thermoplastic Aligners. Orthod Craniofacial Res. https://doi.org/10.1111/ocr.12887 Castroflorio T, Sedran A, Parrini S, et al (2023) Predictability of orthodontic tooth movement with aligners: effect of treatment design. Prog Orthod 24:. https://doi.org/10.1186/s40510-022-00453-0 Charalampakis O, Iliadi A, Ueno H, et al (2018) Accuracy of clear aligners: A retrospective study of patients who needed refinement. Am J Orthod Dentofac Orthop 154:47–54. https://doi.org/10.1016/j.ajodo.2017.11.028 Choi Y-K, Jee M-J, Kim S-H, et al (2025) A Comparative In Vitro Analysis of Attachment and Enhanced Structural Features for Molar Distalization in Clear Aligner Therapy. Appl Sci 15:6655. https://doi.org/10.3390/app15126655 Elshazly TM, Bourauel C, Aldesoki M, et al (2024) Effect of attachment configuration and trim line design on the force system of orthodontic aligners: A finite element study on the upper central incisor. Orthod Craniofacial Res 00:1–10. https://doi.org/10.1111/ocr.12779 Erbas S, Atik E (2025) In vitro comparison of different composite resins for aligner attachment production. J Orofac Orthop / Fortschritte der Kieferorthopädie. https://doi.org/10.1007/s00056-025-00588-9 GAiDGE 360 Consulting (2023) 2023 Orthodontic Data Trends + Insights. https:// dynamix-cdn.s3.amazonaws.com/gaidgecom/gaidgecom_840293995.pdf . Accessed 8 Dec 2025 Geiger ME, Lapatki BG (2014) Locating the center of resistance in individual teeth via two- and three-dimensional radiographic data. J Orofac Orthop / Fortschritte der Kieferorthopädie 75:96–106. https://doi.org/10.1007/s00056-013-0198-0 Haouili N, Kravitz ND, Vaid NR, et al (2020) Has Invisalign improved? A prospective follow-up study on the efficacy of tooth movement with Invisalign. Am J Orthod Dentofac Orthop 158:420–425. https://doi.org/10.1016/j.ajodo.2019.12.015 Hong K, Kim W, Eghan-Acquah E, et al (2021) Efficient design of a clear aligner attachment to induce bodily tooth movement in orthodontic treatment using finite element analysis. Materials (Basel) 14:. https://doi.org/10.3390/ma14174926 Jedliński M, Mazur M, Greco M, et al (2023) Attachments for the Orthodontic Aligner Treatment—State of the Art—A Comprehensive Systematic Review. Int J Environ Res Public Health 20:. https://doi.org/10.3390/ijerph20054481 Jones ML, Mah J, O’Toole BJ (2009) Retention of thermoformed aligners with attachments of various shapes and positions. J Clin Orthod 43:113–117 Kiong M, Ashari A, Zamani NSM, et al (2024) Effect of attachment flash on clear aligner force delivery: an in vitro study. BMC Oral Health 24:538. https://doi.org/10.1186/s12903-024-04284-9 Larson Z (2022) The Effect of Attachment Flash on Clear Aligner Force Delivery. University of Minnesota Lombardo G, Vena F, Negri P, et al (2020) Worldwide prevalence of malocclusion in the different stages of dentition: A systematic review and meta-analysis. Eur J Paediatr Dent 21:115–122. https://doi.org/10.23804/ejpd.2020.21.02.05 Lombardo L, Martines E, Mazzanti V, et al (2017) Stress relaxation properties of four orthodontic aligner materials: A 24-hour in vitro study. Angle Orthod 87:11–18. https://doi.org/10.2319/113015-813.1 Magura J, Akbari A, Lear M, et al (2025) In vitro comparison of the effects of direct attachment shape and location on forces and moments generated by thermoplastic aligners during simulated torque movement. Int Orthod 23:100982. https://doi.org/10.1016/j.ortho.2025.100982 Meade MJ, Weir T (2022) A survey of orthodontic clear aligner practices among orthodontists. Am J Orthod Dentofac Orthop 162:302–311. https://doi.org/10.1016/j.ajodo.2022.08.018 Schwarzmann P (2019) Thermoforming: a practical guide. Hanser Publishers, Munich Hanser Publications Straumann Group (2025) ClearQuartz. https://www.straumann.com/clearcorrect/de/de/behandler/clearquartz.html . Accessed 24 Apr 2026 Traversa F, Chavanne P, Mah J (2025) Biomechanics of clear aligner therapy: Assessing the influence of tooth position and flat trimline height in translational movements. Orthod Craniofac Res 28:1–11. https://doi.org/10.1111/ocr.12796 Traversa F, Mah J (2023) Impact of buccopalatal translation and trimline design on clear aligners: An in vitro study of the maxillary right central incisor. J Aligner Orthod 7:1–10 Table 2 Table 2 is available in the Supplementary Files section. Additional Declarations Competing interest reported. Pascal Vollenweider: Employee at Institut Straumann AG. Flavio Traversa: Employee at Institut Straumann AG. James Mah: Paid expert testimony. Michael de Wild: None Philippe Chavanne: None Alain Hedinger: Employee at Institut Straumann AG. Cite Share Download PDF Status: Under Review Version 1 posted Reviews received at journal 18 May, 2026 Reviewers agreed at journal 10 May, 2026 Reviewers agreed at journal 06 May, 2026 Reviewers invited by journal 06 May, 2026 Editor assigned by journal 30 Apr, 2026 Submission checks completed at journal 30 Apr, 2026 First submitted to journal 24 Apr, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {\"props\":{\"pageProps\":{\"initialData\":{\"identity\":\"rs-9517209\",\"acceptedTermsAndConditions\":true,\"allowDirectSubmit\":false,\"archivedVersions\":[],\"articleType\":\"Research Article\",\"associatedPublications\":[],\"authors\":[{\"id\":637811800,\"identity\":\"528847a7-5fce-4b4e-80d4-02a2b9fccbd3\",\"order_by\":0,\"name\":\"Pascal Vollenweider\",\"email\":\"data:image/png;base64,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\",\"orcid\":\"\",\"institution\":\"Straumann (Switzerland)\",\"correspondingAuthor\":true,\"prefix\":\"\",\"firstName\":\"Pascal\",\"middleName\":\"\",\"lastName\":\"Vollenweider\",\"suffix\":\"\"},{\"id\":637811801,\"identity\":\"08897d91-99fd-4ab9-9c04-bdbf96e28501\",\"order_by\":1,\"name\":\"Flavio Traversa\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"Straumann (Switzerland)\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Flavio\",\"middleName\":\"\",\"lastName\":\"Traversa\",\"suffix\":\"\"},{\"id\":637811802,\"identity\":\"377c106f-6ad3-4005-bd98-35dedbad4e56\",\"order_by\":2,\"name\":\"James Mah\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"University of Nevada, Las Vegas\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"James\",\"middleName\":\"\",\"lastName\":\"Mah\",\"suffix\":\"\"},{\"id\":637811803,\"identity\":\"e8da9aed-2ed6-4efb-a079-92700e42808f\",\"order_by\":3,\"name\":\"Michael de Wild\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"University of Applied Sciences and Arts Northwestern Switzerland\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Michael\",\"middleName\":\"\",\"lastName\":\"de Wild\",\"suffix\":\"\"},{\"id\":637811804,\"identity\":\"0b2912f3-cdf9-40c0-b619-1e437d161542\",\"order_by\":4,\"name\":\"Philippe Chavanne\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Philippe\",\"middleName\":\"\",\"lastName\":\"Chavanne\",\"suffix\":\"\"},{\"id\":637811805,\"identity\":\"b2b69b4d-8455-4261-a1a1-949edf5e09c8\",\"order_by\":5,\"name\":\"Alain Hedinger\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"Straumann (Switzerland)\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Alain\",\"middleName\":\"\",\"lastName\":\"Hedinger\",\"suffix\":\"\"}],\"badges\":[],\"createdAt\":\"2026-04-24 12:25:07\",\"currentVersionCode\":1,\"declarations\":\"\",\"doi\":\"10.21203/rs.3.rs-9517209/v1\",\"doiUrl\":\"https://doi.org/10.21203/rs.3.rs-9517209/v1\",\"draftVersion\":[],\"editorialEvents\":[],\"editorialNote\":\"\",\"failedWorkflow\":false,\"files\":[{\"id\":109305592,\"identity\":\"96c7d02a-6690-46ff-90e0-c9d8328c682c\",\"added_by\":\"auto\",\"created_at\":\"2026-05-15 10:02:40\",\"extension\":\"pdf\",\"order_by\":0,\"title\":\"\",\"display\":\"\",\"copyAsset\":false,\"role\":\"manuscript-pdf\",\"size\":329687,\"visible\":true,\"origin\":\"\",\"legend\":\"\",\"description\":\"\",\"filename\":\"manuscript.pdf\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-9517209/v1/3dce0af3-79fc-4040-b920-cd9ec2559333.pdf\"}],\"financialInterests\":\"Competing interest reported. Pascal Vollenweider: Employee at Institut Straumann AG.\\nFlavio Traversa: Employee at Institut Straumann AG.\\nJames Mah: Paid expert testimony. \\nMichael de Wild: None\\nPhilippe Chavanne: None\\nAlain Hedinger: Employee at Institut Straumann AG.\",\"formattedTitle\":\"Improving Facial Crown Tipping with Clear Aligners: the role of attachment design and composite flash\",\"fulltext\":[{\"header\":\"Introduction\",\"content\":\"\\u003cp\\u003eClear aligner therapy (CAT) has become a widely adopted alternative to conventional fixed appliances, particularly among adult patients seeking aesthetic and minimally invasive treatment. Driven by advances in digital workflows and material science, its global adoption continues to grow. Malocclusions affect approximately 56% of the global population (Lombardo et al. \\u003cspan citationid=\\\"CR18\\\" class=\\\"CitationRef\\\"\\u003e2020\\u003c/span\\u003e). In Australia, 24.17% of orthodontic cases are managed exclusively with clear aligners (Meade and Weir \\u003cspan citationid=\\\"CR21\\\" class=\\\"CitationRef\\\"\\u003e2022\\u003c/span\\u003e). This trend is further confirmed by GAiDGE\\u0026rsquo;s 2023 annual report showing about one third of all orthodontic treatments are started with clear aligners (GAiDGE 360 Consulting \\u003cspan citationid=\\\"CR10\\\" class=\\\"CitationRef\\\"\\u003e2023\\u003c/span\\u003e).\\u003c/p\\u003e \\u003cp\\u003eThe digitalization of orthodontics has allowed for fully digital workflows, which include intraoral scanning, computer-aided design (CAD), and 3D printing. CAD/computer-aided manufacturing (CAM) technologies enable the customization of aligners and auxiliaries such as attachments (added composite material on clinical crown), whose geometry and positioning can be defined digitally before clinical application. Additionally, modern aligners are manufactured from multi-layer thermoplastic polymers designed to optimize force delivery and reduce stress relaxation.(Bichu et al. \\u003cspan citationid=\\\"CR3\\\" class=\\\"CitationRef\\\"\\u003e2023\\u003c/span\\u003e)\\u003c/p\\u003e \\u003cp\\u003eDespite technological advances, achieving precise and predictable dental movements remains consistently challenging.(Castroflorio et al. \\u003cspan citationid=\\\"CR5\\\" class=\\\"CitationRef\\\"\\u003e2023\\u003c/span\\u003e) Crown tipping, although reported as one of the easiest movements in CAT (difficulty classification 1.79\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;1.35 on a 6-point scale)(Abu-Arqub et al. \\u003cspan citationid=\\\"CR1\\\" class=\\\"CitationRef\\\"\\u003e2023\\u003c/span\\u003e), shows low clinical precision between planned and executed movements, with reported predictability for faciolingual inclination as low as 56% (Haouili et al. \\u003cspan citationid=\\\"CR12\\\" class=\\\"CitationRef\\\"\\u003e2020\\u003c/span\\u003e). The maxillary lateral incisor in turn was mentioned as frequently problematic in CAT by 21 independent orthodontists.(Meade and Weir \\u003cspan citationid=\\\"CR21\\\" class=\\\"CitationRef\\\"\\u003e2022\\u003c/span\\u003e)\\u003c/p\\u003e \\u003cp\\u003eComposite attachments are standard auxiliaries in CAT; their shape and positioning affect both aligner retention and the expression of force on the clinical crown.(Jedliński et al. \\u003cspan citationid=\\\"CR14\\\" class=\\\"CitationRef\\\"\\u003e2023\\u003c/span\\u003e) Jedliński et al. (\\u003cspan citationid=\\\"CR14\\\" class=\\\"CitationRef\\\"\\u003e2023\\u003c/span\\u003e) reviewed 22 publications on the influence of attachments on movement efficacy, but none of them specifically looked into the effects of excessive material, often remaining on the clinical crown after bonding, on the ME. Jones et al. (\\u003cspan citationid=\\\"CR15\\\" class=\\\"CitationRef\\\"\\u003e2009\\u003c/span\\u003e) reported a higher retention force for gingivally placed attachments compared to occlusally placed attachments (rectangular and beveled shape). In their discussion, they identify the lack of clinical evidence for the correlation between highly retentive aligners and efficiency of the aligner treatment.\\u003c/p\\u003e \\u003cp\\u003eImproperly designed or placed attachments may lead to inefficient force distribution or unintended loading on adjacent teeth and excessive composite material (\\u0026ldquo;flash\\u0026rdquo;) prevent complete aligner seating, compromise fit and pressure distribution and reduce movement predictability.(Larson \\u003cspan citationid=\\\"CR17\\\" class=\\\"CitationRef\\\"\\u003e2022\\u003c/span\\u003e; Kiong et al. \\u003cspan citationid=\\\"CR16\\\" class=\\\"CitationRef\\\"\\u003e2024\\u003c/span\\u003e) Comparing different composite materials used for bonding attachments, a gel-like composite (Filtek Z350 XT universal) was found to be less prone to flash generation, staining and debonding compared to flowable composites (Z350 XT flowable).(Erbas and Atik \\u003cspan citationid=\\\"CR9\\\" class=\\\"CitationRef\\\"\\u003e2025\\u003c/span\\u003e)\\u003c/p\\u003e \\u003cp\\u003eTo achieve a controlled facial tipping, the faciolingual torque (CT\\u003csub\\u003efacial\\u003c/sub\\u003e) is the primary biomechanical driver. The clinical goal is to maximize this torque while avoiding undesired side effects in the form of unplanned forces and torques. Faciolingual (F\\u003csub\\u003efl\\u003c/sub\\u003e), mesiodistal (F\\u003csub\\u003emd\\u003c/sub\\u003e), and apico-occlusal (F\\u003csub\\u003eao\\u003c/sub\\u003e) forces as well as their associated mesiodistal, faciolingual, and mesiolingual/distolingual torque contribute to unintended movements such as distal drift, vertical intrusion/extrusion, or unwanted rotations. These components also act on adjacent teeth or destabilize the targeted tooth\\u0026rsquo;s movement, thereby increasing the likelihood of refinement.\\u003c/p\\u003e \\u003cp\\u003ePrevious investigations on clear aligner auxiliaries have examined either attachment geometry or position in isolation, often using finite element models of central incisors or molars and focusing on translational movements or extrusion rather than crown tipping.(Hong et al. \\u003cspan citationid=\\\"CR13\\\" class=\\\"CitationRef\\\"\\u003e2021\\u003c/span\\u003e; Alhasyimi et al. \\u003cspan citationid=\\\"CR2\\\" class=\\\"CitationRef\\\"\\u003e2024\\u003c/span\\u003e; Magura et al. \\u003cspan citationid=\\\"CR20\\\" class=\\\"CitationRef\\\"\\u003e2025\\u003c/span\\u003e; Choi et al. \\u003cspan citationid=\\\"CR7\\\" class=\\\"CitationRef\\\"\\u003e2025\\u003c/span\\u003e) Root torque of a central incisor was investigated in-vitro comparing ellipsoidal and rectangular attachments at different vertical positions using an orthodontic force tester (Magura et al. \\u003cspan citationid=\\\"CR20\\\" class=\\\"CitationRef\\\"\\u003e2025\\u003c/span\\u003e). The vertical position of the attachment was shown to significantly influence the forces and moments generated on the tooth with the central third and ellipsoid design being the most favorable. Recent in-vitro studies on composite flash have demonstrated that flash increases unwanted forces, but they typically evaluated a single attachment type on isolated teeth and did not explore how flash interacts with attachment position in a full-arch biomechanical system.(Larson \\u003cspan citationid=\\\"CR17\\\" class=\\\"CitationRef\\\"\\u003e2022\\u003c/span\\u003e; Kiong et al. \\u003cspan citationid=\\\"CR16\\\" class=\\\"CitationRef\\\"\\u003e2024\\u003c/span\\u003e) Kiong et al. (\\u003cspan citationid=\\\"CR16\\\" class=\\\"CitationRef\\\"\\u003e2024\\u003c/span\\u003e) used a pressure foil to visualize the pressure on the crown generated by different attachment configurations including flash, however, the study design fails to quantify the effective forces generated at the center of resistance. To date, there is no experimental 6 degrees of freedom analysis quantifying the combined effects of attachment geometry, vertical positioning, and composite flash on facial crown tipping of the maxillary lateral incisor, a tooth that displays low predictability in clear aligner therapy (Charalampakis et al. \\u003cspan citationid=\\\"CR6\\\" class=\\\"CitationRef\\\"\\u003e2018\\u003c/span\\u003e) and is frequently identified by clinicians as problematic.(Meade and Weir \\u003cspan citationid=\\\"CR21\\\" class=\\\"CitationRef\\\"\\u003e2022\\u003c/span\\u003e)\\u003c/p\\u003e \\u003cp\\u003eTherefore, this in-vitro study aimed to (1) compare rectangular and beveled attachment designs at different vertical positions, (2) evaluate the impact of composite flash and deliberate vertical misplacement on the ME (CT\\u003csub\\u003efacial\\u003c/sub\\u003e / F\\u003csub\\u003efl\\u003c/sub\\u003e), and (3) characterize how these modifications alter load transmission to adjacent teeth in a full maxillary arch. All these investigations were investigated on the maxillary lateral incisor while additionally reporting the loadings experienced by the closest neighbors.\\u003c/p\\u003e\"},{\"header\":\"Material and Methods\",\"content\":\"\\u003cdiv id=\\\"Sec3\\\" class=\\\"Section2\\\"\\u003e\\n \\u003ch2\\u003eExperimental Setup\\u003c/h2\\u003e\\n \\u003cp\\u003eA mechanical in vitro analysis was conducted using the Orthodontic Force Simulator (OFS; Institut Straumann, Basel, Switzerland) to evaluate seven attachment configurations on the maxillary right lateral incisor. Each design was tested using five identical thermoformed aligners manufactured from 0.762 mm ClearQuartz\\u0026trade; sheets (ClearCorrect\\u0026reg;, Basel, Switzerland), totaling 35 aligners. The analysis focused on the force and torque systems generated during a simulated 3\\u0026deg; lingual crown angulation movement, with the ME (CT\\u003csub\\u003efacial\\u003c/sub\\u003e/F\\u003csub\\u003efl\\u003c/sub\\u003e) as the primary outcome reflecting the purity of the tipping movement.\\u003c/p\\u003e\\n\\u003c/div\\u003e\\n\\u003ch3\\u003eOrthodontic Force Simulator and measured variables\\u003c/h3\\u003e\\n\\u003cp\\u003eThe OFS employed the same advanced in-vitro testing apparatus described in previous studies, comprising both hardware and software components (LabVIEW 2022 Q3 Full, Austin, US).(Traversa and Mah \\u003cspan citationid=\\\"CR25\\\" class=\\\"CitationRef\\\"\\u003e2023\\u003c/span\\u003e) The setup included a dentition model symmetric to the sagittal plane, with each tooth mounted on a 6-channel force and torque sensor (MMS101, MinebeaMitsumi Inc., Tokyo, Japan) (See Fig. \\u003cspan refid=\\\"Fig1\\\" class=\\\"InternalRef\\\"\\u003e1\\u003c/span\\u003e).\\u003c/p\\u003e\\n\\u003cp\\u003eSix variables were recorded for each tooth: facio-lingual (F\\u003csub\\u003efl\\u003c/sub\\u003e), mesio-distal (F\\u003csub\\u003emd\\u003c/sub\\u003e), and apico-occlusal (F\\u003csub\\u003eao\\u003c/sub\\u003e) forces, as well as the corresponding torques (CT\\u003csub\\u003efacial\\u003c/sub\\u003e, CT\\u003csub\\u003emd\\u003c/sub\\u003e, R\\u003csub\\u003emldl\\u003c/sub\\u003e).\\u003c/p\\u003e\\n\\u003cdiv class=\\\"gridtable\\\"\\u003e\\n \\u003cdiv align=\\\"left\\\" class=\\\"colspec\\\" colname=\\\"c2\\\" colnum=\\\"2\\\"\\u003e\\u003cbr\\u003e\\u003c/div\\u003e\\u0026nbsp;\\u003ctable float=\\\"Yes\\\" id=\\\"Tab1\\\" border=\\\"1\\\"\\u003e\\n \\u003ccaption language=\\\"En\\\"\\u003e\\n \\u003cdiv class=\\\"CaptionNumber\\\"\\u003eTable 1\\u003c/div\\u003e\\n \\u003cdiv class=\\\"CaptionContent\\\"\\u003e\\n \\u003cp\\u003ePositive direction for the lateral incisor\\u003c/p\\u003e\\n \\u003c/div\\u003e\\n \\u003c/caption\\u003e\\n \\u003ccolgroup cols=\\\"2\\\"\\u003e\\u003c/colgroup\\u003e\\n \\u003cthead\\u003e\\n \\u003ctr\\u003e\\n \\u003cth align=\\\"left\\\" colname=\\\"c1\\\"\\u003e\\n \\u003cp\\u003eVariable\\u003c/p\\u003e\\n \\u003c/th\\u003e\\n \\u003cth align=\\\"left\\\" colname=\\\"c2\\\"\\u003e\\n \\u003cp\\u003ePositive direction\\u003c/p\\u003e\\n \\u003c/th\\u003e\\n \\u003c/tr\\u003e\\n \\u003c/thead\\u003e\\n \\u003ctbody\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e\\n \\u003cp\\u003eF\\u003csub\\u003efl\\u003c/sub\\u003e\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e\\n \\u003cp\\u003elingual\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e\\n \\u003cp\\u003eF\\u003csub\\u003emd\\u003c/sub\\u003e\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e\\n \\u003cp\\u003edistal\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e\\n \\u003cp\\u003eF\\u003csub\\u003eao\\u003c/sub\\u003e\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e\\n \\u003cp\\u003eocclusal\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e\\n \\u003cp\\u003eCT\\u003csub\\u003efacial\\u003c/sub\\u003e\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e\\n \\u003cp\\u003efacial\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e\\n \\u003cp\\u003eCT\\u003csub\\u003emd\\u003c/sub\\u003e\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e\\n \\u003cp\\u003edistal\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e\\n \\u003cp\\u003eR\\u003csub\\u003emldl\\u003c/sub\\u003e\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e\\n \\u003cp\\u003edisto-lingual\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003c/tbody\\u003e\\n \\u003c/table\\u003e\\n\\u003c/div\\u003e\\n\\u003cp\\u003e\\u003cbr\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003ePositive directions for the six variables are listed in Table \\u003cspan refid=\\\"Tab1\\\" class=\\\"InternalRef\\\"\\u003e1\\u003c/span\\u003e, also indicated visually in Fig. \\u003cspan refid=\\\"Fig1\\\" class=\\\"InternalRef\\\"\\u003e1\\u003c/span\\u003e by the direction of the arrows displayed.\\u003c/p\\u003e\\n\\u003cp\\u003eThe right lateral incisor was mounted on a six-axis hexapod (H-811.I2, Physik Instrumente (PI) GmbH \\u0026amp; Co. KG, Germany), allowing translations and rotations in all six degrees of freedom during the experiment. An individual transformation matrix was applied for each tooth to transfer the measured loadings at the sensor to the tooth\\u0026rsquo;s center of resistance (CoR), which was defined based on established literature.(Geiger and Lapatki \\u003cspan citationid=\\\"CR11\\\" class=\\\"CitationRef\\\"\\u003e2014\\u003c/span\\u003e) Despite six degrees of freedom were measured for all 14 teeth of the simulated maxillary arch, only the facial crown torque (CT\\u003csub\\u003efacial\\u003c/sub\\u003e) and the facio-lingual force (F\\u003csub\\u003efl\\u003c/sub\\u003e) of the lateral incisor were further considered for the ME. CT\\u003csub\\u003efacial\\u003c/sub\\u003e is the primary driver of the planned facial crown tipping and F\\u003csub\\u003efl\\u003c/sub\\u003e is the expected largest side effect.\\u003c/p\\u003e\\n\\u003ch3\\u003eClear Aligner Fabrication\\u003c/h3\\u003e\\n\\u003cp\\u003eThe OFS dentition was scanned in a neutral position using an intraoral scanner (Virtuo Vivo, Straumann, Basel, Switzerland). The scan data were then virtually superimposed with the original gingiva. The interproximal spaces were filled with small wedge-shaped geometries (see Fig. \\u003cspan refid=\\\"Fig1\\\" class=\\\"InternalRef\\\"\\u003e1\\u003c/span\\u003ec). Before 3D printing, the models were scaled to 100.4% to compensate for shrinkage effects during the production workflow.(Schwarzmann \\u003cspan citationid=\\\"CR22\\\" class=\\\"CitationRef\\\"\\u003e2019\\u003c/span\\u003e) The generated models were then 3D printed using VeroWhite resin with an Objet260 printer (Stratasys, Rehovot, Israel), and the support material was manually removed using a water jet machine. This procedure was repeated for each of the different designs. One 3D model was printed for each design, and five aligners were thermoformed with each, resulting in a total of seven models and 35 aligners.\\u003c/p\\u003e\\n\\u003cp\\u003eClearQuartz sheets with a thickness of 0.76 mm (ClearCorrect, Basel, Switzerland) were thermoformed at a pressure of 6 bars using a Drufomat thermoforming machine (Dreve Dentamid GmbH, Unna, Germany). ClearQuartz is a 3-layer material containing thermoplastic urethane, known for its low stress relaxation rate and low initial forces.(Lombardo et al. \\u003cspan citationid=\\\"CR19\\\" class=\\\"CitationRef\\\"\\u003e2017\\u003c/span\\u003e; Straumann Group \\u003cspan citationid=\\\"CR23\\\" class=\\\"CitationRef\\\"\\u003e2025\\u003c/span\\u003e) To ease separation of the thermoformed sheet from the 3D printed arch model, a separation liquid (Aqualease\\u0026trade; 75, Mann release technologies\\u0026trade;, Macungie, Pennsylvania, USA) was used. After thermoforming, the sheets were separated from the 3D printed arch model, and a flat trimline 2 mm above the gingival margin was cut using a laser cutting machine (LAC, DMU - Dental Manufacturing Unit GmbH, Puch bei Hallein, Austria). The extended flat trimline was selected for its superior retention and enhanced control of tooth movement.(Elshazly et al. \\u003cspan citationid=\\\"CR8\\\" class=\\\"CitationRef\\\"\\u003e2024\\u003c/span\\u003e) All aligners were produced based on the neutral dentition scan, meaning the printed arch models used for thermoforming did not have any tooth movements programmed. After manufacturing, aligners were cleaned with dishwasher soap and water to remove the remaining separation liquid and stored in testing environment under ambient conditions for 48 hours prior testing.\\u003c/p\\u003e\\n\\u003ch3\\u003eTesting Procedures\\u003c/h3\\u003e\\n\\u003cp\\u003eAll measurements performed on the OFS were conducted at room temperature (21\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;1\\u0026deg;C). The aligners were moisturized with distilled water on the contact surface prior to insertion on the OFS dentition. The right lateral incisor, mounted on the hexapod, was 3\\u0026deg; lingually tipped (rotation around its CoR) to simulate a planned facial crown tipping scenario from the aligner perspective. This procedure reflects a clinically realistic scenario of facial tipping where the aligner has 3\\u0026deg; facial tipping programmed and the lateral incisor is 3\\u0026deg; more lingual than programmed in the aligner shape. To isolate the effects on the arch, no movement was programmed in the rest of the arch. After the 3\\u0026deg; lingual deflection of the lateral incisor, the aligner was inserted on the dentition within 5 seconds. Subsequently, a 10-second measurement period was further used for all six degrees of freedom. Each of the five aligners per design was tested twice, resulting in 10 measurements per crown design and a total of 70 measurements. The aligners rested for at least 5 minutes between the testing rounds.\\u003c/p\\u003e\\n\\u003ch3\\u003eAttachment (Crown) Designs\\u003c/h3\\u003e\\n\\u003cp\\u003eThe lateral incisor used in this study has a maximal crown width of 6.5 mm and a total length of 20.5 mm, where the CoR is located 6.3 mm towards occlusal from the apical point of the root. The crown length from the incisal edge to the cervical point is 8.7 mm and thus the root length 11.8 mm.\\u003c/p\\u003e\\n\\u003cp\\u003eSeven different attachment designs were evaluated in this study and are summarized in Table \\u003cspan refid=\\\"Tab2\\\" class=\\\"InternalRef\\\"\\u003e2\\u003c/span\\u003e. The control design (NoAt) represents the bare crown without any attachments. The recV design simulates a perfect vertical rectangular attachment, while recVf represents a vertical rectangular attachment with added flash. The recVfs design features a vertically oriented rectangular geometry with added flash and is shifted 1 mm toward the incisal edge. The 1 mm shift was selected based on practical usability verification with clinical users, comparing the achieved attachment position to the planned digital position. Achieved positions were captured with an intraoral scanner (Virtuo Vivo, Straumann, Basel, Switzerland) and assessed against the corresponding digital reference. The beveled designs (bevC, bevO, bevG) represent beveled attachments positioned at three different vertical positions. The 2 mm apical displacement was selected as it represents the maximum possible shift from the center towards the gingival margin while maintaining a safe distance from the gingiva in the dentition model. This ensures that the attachment could be bonded at this position in a clinical setting without the risk of damaging the gingiva. Additionally, thermoforming shows limitations in adaptability in areas of small slits or holes, which is why the gap between the gingiva and the attachment must be large enough to allow proper thermoforming adaptation. The incisal shift was also set to 2 mm due to consistency. Both, the rectangular and the beveled attachment shape are commercially available designs, distributed by ClearCorrect (Straumann Group, Basel, Switzerland). All aligners were manufactured based on the designs described above, except for recVf and recVfs. To reflect the clinical situation, the aligners for these two designs were manufactured based on recV, creating a deliberate mismatch between the aligner and the dentition, simulating clinical scenarios of flash and mispositioning.\\u003c/p\\u003e\\n\\u003cdiv id=\\\"Sec8\\\" class=\\\"Section2\\\"\\u003e\\n \\u003ch2\\u003eStatistical Analysis\\u003c/h2\\u003e\\n \\u003cp\\u003eThe primary outcome of the designs tested is their ME. The ME for facial crown tipping is defined as the torque generating the crown tipping (CT\\u003csub\\u003efacial\\u003c/sub\\u003e) divided by the expected largest side effect (F\\u003csub\\u003efl\\u003c/sub\\u003e).\\u003c/p\\u003e\\n\\u003c/div\\u003e\\n\\u003ch3\\u003eME (ME):\\u003c/h3\\u003e\\n\\u003cdiv class=\\\"Heading\\\"\\u003eME (ME): \\u003cspan class=\\\"InlineEquation\\\"\\u003e\\u003cspan class=\\\"mathinline\\\"\\u003e\\\\(\\\\:\\\\frac{{CT}_{facial}}{{F}_{fl}}\\\\)\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/div\\u003e\\n\\u003cp\\u003eDue to the setup design, a facial crown torque is defined in positive direction, and a facial force is defined in negative direction, which creates negative efficiency values for all designs a facial force is present. For the assessment of the ME, only the magnitude of the ME is relevant, the sign can therefore be ignored but is not removed due to originality of the data. The higher the absolute value of ME, the more precise the movement is assumed to happen clinically. The following hypothesis shall be tested regarding significant differences:\\u003c/p\\u003e\\n\\u003ch3\\u003eComposite flash and position\\u003c/h3\\u003e\\n\\u003cp\\u003eH1.1: Composite flash around the attachment (recVf) shows a significant lower ME compared to an optimal attachment design (recV).\\u003c/p\\u003e\\n\\u003cp\\u003eH1.2: Composite flash and a vertical shift (recVfs) show a significant lower ME compared to an optimal attachment design (recV).\\u003c/p\\u003e\\n\\u003cdiv id=\\\"Sec11\\\" class=\\\"Section2\\\"\\u003e\\n \\u003ch2\\u003eAttachment shape\\u003c/h2\\u003e\\n \\u003cp\\u003eH2.1a: The presence of a centrally placed rectangular attachment (recV) significantly increases ME compared to no attachment (NoAt).\\u003c/p\\u003e\\n \\u003cp\\u003eH2.1b: The presence of a centrally placed beveled attachment (bevC) significantly increases ME compared to no attachment (NoAt).\\u003c/p\\u003e\\n \\u003cp\\u003eH2.2: The beveled (bevC) and rectangular attachment (recV) show no significant difference in ME when centrally placed on the crown.\\u003c/p\\u003e\\n\\u003c/div\\u003e\\n\\u003cdiv id=\\\"Sec12\\\" class=\\\"Section2\\\"\\u003e\\n \\u003ch2\\u003eVertical position\\u003c/h2\\u003e\\n \\u003cp\\u003eH3.1: The beveled attachment placed more gingival (bevG) shows significant higher ME compared to centrally placed (bevC).\\u003c/p\\u003e\\n \\u003cp\\u003eH3.2:The beveled attachment placed more occlusal (bevO) shows significant lower ME compared to centrally placed (bevC).\\u003c/p\\u003e\\n \\u003cp\\u003eStatistical analyses were performed in R (RStudio, version 4.3.1) using a reproducible RMarkdown workflow. The raw data from the Orthodontic Force Simulator (OFS) containing 3 force and 3 torque measurements together with a time stamp for each tooth were converted to an Excel spreadsheet. Only values for the lateral incisor are reported here, except for Fig. \\u003cspan refid=\\\"Fig3\\\" class=\\\"InternalRef\\\"\\u003e3\\u003c/span\\u003e, where the loading experienced by adjacent teeth is also visualized. The Excel files were imported via the readxl package, and numeric variables were converted from European decimal format (comma as decimal separator) to standard numeric format. Data processing and grouping were handled with dplyr, and graphical assessments were performed using ggplot2.\\u003c/p\\u003e\\n \\u003cp\\u003eNormality within each study group and measurement repetition (7 study groups, 2 measurement repetitions) was evaluated using the Shapiro-Wilk test and the Kolmogorov-Smirnov test with Lilliefors correction (nortest package). Complementary quantile-quantile (QQ) plots were generated for visual inspection of the distributional assumptions.\\u003c/p\\u003e\\n \\u003cp\\u003eAll normality tests yielded highly significant p-values, and the corresponding QQ-plots clearly indicated deviations from normal distribution in all subgroups. Therefore, subsequent analyses were performed using non-parametric statistical methods.\\u003c/p\\u003e\\n \\u003cp\\u003eComparative analyses of ME (CT\\u003csub\\u003efacial\\u003c/sub\\u003e / F\\u003csub\\u003efl\\u003c/sub\\u003e) were performed across study groups to test the above-mentioned hypothesis regarding the effect of different attachment designs and placements. Due to the lack of normal distribution in all subgroups (assessed by Shapiro-Wilk and Kolmogorov-Smirnov tests with Lilliefors correction), non-parametric statistical methods were applied.\\u003c/p\\u003e\\n \\u003cp\\u003eFor each hypothesis, the Mann-Whitney U test (wilcox.test in R) was used to compare the ME between the two designs and their test rounds. Since each aligner was measured twice, tests were performed separately for each repetition (Repetition 1 and Repetition 2). Boxplots were generated (see Online Resource 1) to visualize the distribution of ME across cases and repetitions.\\u003c/p\\u003e\\n\\u003c/div\\u003e\"},{\"header\":\"Results\",\"content\":\"\\u003cdiv id=\\\"Sec14\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003eMovement Efficiency (ME)\\u003c/h2\\u003e \\u003cp\\u003eThe raw data measurements for the facial crown torque of the lateral incisor with no attachment (NoAt) are visualized in Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig2\\\" class=\\\"InternalRef\\\"\\u003e2\\u003c/span\\u003e. The first 5 seconds are cut due to manual insertion, measurements between 5 and 15 seconds are used for further analysis. This kind of raw data cut was performed for all 7 crown designs and their corresponding force and torque measurements.\\u003c/p\\u003e \\u003cp\\u003e \\u003c/p\\u003e \\u003cp\\u003eThe normality of each data section was assessed using the Shapiro-Wilk test and the Kolmogorov-Smirnov test with Lilliefors correction as well as QQ-plots for visual inspection. Since all tests showed significant differences from a normal distribution for all sections, the Wilcoxon rank sum test with continuity correction was applied to test significant different (α\\u0026thinsp;=\\u0026thinsp;0.05) MEs between designs.\\u003c/p\\u003e \\u003cp\\u003e \\u003cdiv class=\\\"gridtable\\\"\\u003e\\u003ctable float=\\\"Yes\\\" id=\\\"Tab3\\\" border=\\\"1\\\"\\u003e \\u003ccaption language=\\\"En\\\"\\u003e \\u003cdiv class=\\\"CaptionNumber\\\"\\u003eTable 3\\u003c/div\\u003e \\u003cdiv class=\\\"CaptionContent\\\"\\u003e \\u003cp\\u003eME of tested Designs (Median, IQR)\\u003c/p\\u003e \\u003c/div\\u003e \\u003c/caption\\u003e \\u003ccolgroup cols=\\\"5\\\"\\u003e \\u003cdiv align=\\\"left\\\" class=\\\"colspec\\\" colname=\\\"c1\\\" colnum=\\\"1\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"left\\\" class=\\\"colspec\\\" colname=\\\"c2\\\" colnum=\\\"2\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"left\\\" class=\\\"colspec\\\" colname=\\\"c3\\\" colnum=\\\"3\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"left\\\" class=\\\"colspec\\\" colname=\\\"c4\\\" colnum=\\\"4\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"left\\\" class=\\\"colspec\\\" colname=\\\"c5\\\" colnum=\\\"5\\\"\\u003e\\u003c/div\\u003e \\u003cthead\\u003e \\u003ctr\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c1\\\" morerows=\\\"1\\\" rowspan=\\\"2\\\"\\u003e\\u0026nbsp;\\u003c/th\\u003e \\u003cth align=\\\"left\\\" colspan=\\\"4\\\" nameend=\\\"c5\\\" namest=\\\"c2\\\"\\u003e \\u003cp\\u003eMovement Efficiency (CT\\u003csub\\u003efacial\\u003c/sub\\u003e / F\\u003csub\\u003efl\\u003c/sub\\u003e)\\u003c/p\\u003e \\u003c/th\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003cth align=\\\"left\\\" colspan=\\\"2\\\" nameend=\\\"c3\\\" namest=\\\"c2\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003eRepetition 1\\u003c/b\\u003e\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colspan=\\\"2\\\" nameend=\\\"c5\\\" namest=\\\"c4\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003eRepetition 2\\u003c/b\\u003e\\u003c/p\\u003e \\u003c/th\\u003e \\u003c/tr\\u003e \\u003c/thead\\u003e \\u003ctbody\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e\\u0026nbsp;\\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003eMedian\\u003c/b\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003eIQR\\u003c/b\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003eMedian\\u003c/b\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003eIQR\\u003c/b\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eNoAt\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e-1.88\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e[-1.92, -1.83]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e-1.89\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e[-1.91, -1.72]\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003erecV\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e-4.06\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e[-4.13, -3.86]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e-4.01\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e[-4.12, -3.96]\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003erecVf\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e-2.50\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e[-2.55, -2.48]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e-2.46\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e[-2.49, -2.44]\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003erecVfs\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e-1.58\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e[-1.66, -1.42]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e-1.73\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e[-1.8, -1.64]\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003ebevC\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e-3.56\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e[-3.69, -3.5]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e-3.76\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e[-3.79, -3.71]\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003ebevO\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e-3.15\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e[-3.21, -3.1]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e-3.15\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e[-3.17\\u0026ndash;2.95]\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003ebevG\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e-4.45\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e[-4.58, -4.42]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e-4.51\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e[-4.54, -4.42]\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003c/tbody\\u003e \\u003c/colgroup\\u003e \\u003c/table\\u003e\\u003c/div\\u003e \\u003c/p\\u003e \\u003cp\\u003eThe median ME values along with their interquartile ranges (IQR) are listed in Table\\u0026nbsp;\\u003cspan refid=\\\"Tab3\\\" class=\\\"InternalRef\\\"\\u003e3\\u003c/span\\u003e. Since all measurements showed a facial force (negative sensor reading) and a facial crown torque (positive sensor reading), all ME values are negative. As mentioned in the methods section, the higher the absolute value of the ME, the more precise the movement is expected to happen clinically. For further interpretation, descriptions about ME values only consider their magnitude. Based on the results shown, the beveled attachment design 2 mm shifted towards the gingival margin shows the highest ME (bevG, Median: -4.45, -4.51) where the rectangular attachments with added flash and 1 mm occlusal shift revealed the lowest ME (recVfs, Median: -1.58, -1.73).\\u003c/p\\u003e \\u003cp\\u003e \\u003cdiv class=\\\"gridtable\\\"\\u003e\\u003ctable float=\\\"Yes\\\" id=\\\"Tab4\\\" border=\\\"1\\\"\\u003e \\u003ccaption language=\\\"En\\\"\\u003e \\u003cdiv class=\\\"CaptionNumber\\\"\\u003eTable 4\\u003c/div\\u003e \\u003cdiv class=\\\"CaptionContent\\\"\\u003e \\u003cp\\u003eHypothesis Tests based on Wilcoxon rank sum test\\u003c/p\\u003e \\u003c/div\\u003e \\u003c/caption\\u003e \\u003ccolgroup cols=\\\"6\\\"\\u003e \\u003cdiv align=\\\"left\\\" class=\\\"colspec\\\" colname=\\\"c1\\\" colnum=\\\"1\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"left\\\" class=\\\"colspec\\\" colname=\\\"c2\\\" colnum=\\\"2\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"left\\\" class=\\\"colspec\\\" colname=\\\"c3\\\" colnum=\\\"3\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"char\\\" char=\\\".\\\" class=\\\"colspec\\\" colname=\\\"c4\\\" colnum=\\\"4\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"left\\\" class=\\\"colspec\\\" colname=\\\"c5\\\" colnum=\\\"5\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"left\\\" class=\\\"colspec\\\" colname=\\\"c6\\\" colnum=\\\"6\\\"\\u003e\\u003c/div\\u003e \\u003cthead\\u003e \\u003ctr\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eHypothesis\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colspan=\\\"2\\\" nameend=\\\"c3\\\" namest=\\\"c2\\\"\\u003e \\u003cp\\u003eDesign Comparison\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003ep-value\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003eDecision\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003eSuperior Design\\u003c/p\\u003e \\u003c/th\\u003e \\u003c/tr\\u003e \\u003c/thead\\u003e \\u003ctbody\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eH1.1\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003erecV\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003erecVf\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e\\u0026lt;\\u0026thinsp;0.001\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003econfirmed\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003erecV\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eH1.2\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003erecV\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003erecVfs\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e\\u0026lt;\\u0026thinsp;0.001\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003econfirmed\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003erecV\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eH2.1a\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003eNoAt\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003erecV\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e\\u0026lt;\\u0026thinsp;0.001\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003econfirmed\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003erecV\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eH2.1b\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003eNoAt\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003ebevC\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e\\u0026lt;\\u0026thinsp;0.001\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003econfirmed\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003ebevC\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eH2.2\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003erecV\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003ebevC\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e\\u0026lt;\\u0026thinsp;0.001\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003erejected\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003erecV\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eH3.1\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003ebevC\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003ebevG\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e\\u0026lt;\\u0026thinsp;0.001\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003econfirmed\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003ebevG\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eH3.2\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003ebevC\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003ebevO\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e\\u0026lt;\\u0026thinsp;0.001\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003econfirmed\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003ebevC\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003c/tbody\\u003e \\u003c/colgroup\\u003e \\u003c/table\\u003e\\u003c/div\\u003e \\u003c/p\\u003e \\u003cp\\u003eTable\\u0026nbsp;\\u003cspan refid=\\\"Tab4\\\" class=\\\"InternalRef\\\"\\u003e4\\u003c/span\\u003e shows the results comparing the designs based on the different initial hypotheses built. All hypotheses can be accepted except H2.2, where a non-significant difference in ME was expected between the two attachment shapes tested. Corresponding boxplots for each hypothesis can be found in the supplementary material.\\u003c/p\\u003e \\u003c/div\\u003e \\u003cdiv id=\\\"Sec15\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003eLoading Situation\\u003c/h2\\u003e \\u003cp\\u003eWhere the ME is the primary outcome of this study, the force and torque values of the designs tested are still reported in Table\\u0026nbsp;\\u003cspan refid=\\\"Tab5\\\" class=\\\"InternalRef\\\"\\u003e5\\u003c/span\\u003e due to the more detailed insights they provide regarding side effects.\\u003c/p\\u003e \\u003cp\\u003e \\u003cdiv class=\\\"gridtable\\\"\\u003e\\u003ctable float=\\\"Yes\\\" id=\\\"Tab5\\\" border=\\\"1\\\"\\u003e \\u003ccaption language=\\\"En\\\"\\u003e \\u003cdiv class=\\\"CaptionNumber\\\"\\u003eTable 5\\u003c/div\\u003e \\u003cdiv class=\\\"CaptionContent\\\"\\u003e \\u003cp\\u003eMedian [IQR] values of forces and torques measured for the lateral incisor of all designs for each test round (R1, R2)\\u003c/p\\u003e \\u003c/div\\u003e \\u003c/caption\\u003e \\u003ccolgroup cols=\\\"9\\\"\\u003e \\u003cdiv align=\\\"left\\\" class=\\\"colspec\\\" colname=\\\"c1\\\" colnum=\\\"1\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"left\\\" class=\\\"colspec\\\" colname=\\\"c2\\\" colnum=\\\"2\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"left\\\" class=\\\"colspec\\\" colname=\\\"c3\\\" colnum=\\\"3\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"left\\\" class=\\\"colspec\\\" colname=\\\"c4\\\" colnum=\\\"4\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"left\\\" class=\\\"colspec\\\" colname=\\\"c5\\\" colnum=\\\"5\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"left\\\" class=\\\"colspec\\\" colname=\\\"c6\\\" colnum=\\\"6\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"left\\\" class=\\\"colspec\\\" colname=\\\"c7\\\" colnum=\\\"7\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"left\\\" class=\\\"colspec\\\" colname=\\\"c8\\\" colnum=\\\"8\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"left\\\" class=\\\"colspec\\\" colname=\\\"c9\\\" colnum=\\\"9\\\"\\u003e\\u003c/div\\u003e \\u003ctbody\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e\\u0026nbsp;\\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003eRep.\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003eNoAt\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003erecV\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003erecVf\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003erecVfs\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003ebevC\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c8\\\"\\u003e \\u003cp\\u003ebevO\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c9\\\"\\u003e \\u003cp\\u003ebevG\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\" morerows=\\\"1\\\" rowspan=\\\"2\\\"\\u003e \\u003cp\\u003eF\\u003csub\\u003efl\\u003c/sub\\u003e [N]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e1\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e-16.1\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[-16.3, -15.9]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e-6.4\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[-6.8, -6.1]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e-10.4\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[-11.2, -9.6]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e-6.2\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[-6.4, -5.6]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e-8.3\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[-9.1, -7.5]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c8\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e-11.6\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[-12.2, -9.3]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c9\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e-8.9\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[-9.9, -8.8]\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e2\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e-15.9\\u003c/b\\u003e\\u003c/p\\u003e 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\\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e26.1\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[24.5, 28.6]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e9.4\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[8.9, 10.2]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e27.9\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[26.5, 30.6]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c8\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e35.9\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[29.0, 39.1]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c9\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e39.6\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[38.7, 45.4]\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e2\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e27.7\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[27.2, 30.4]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e25.8\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[23.3, 28.7]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e28.0\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[25.1, 28.0]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e9.8\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[8.8, 10.8]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e35.1\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[34.4, 36.2]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c8\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e33.4\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[29.2, 35.8]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c9\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e40.2\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[37.7, 46.0]\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\" morerows=\\\"1\\\" rowspan=\\\"2\\\"\\u003e \\u003cp\\u003eCT\\u003csub\\u003emd\\u003c/sub\\u003e [Ncm]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e1\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e13.7\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[13.3, 14.2]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e1.2\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[0.5, 1.7]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e2.8\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[2.5, 4.3]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e-1.5\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[-1.6, -0.5]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e11.3\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[11.1, 11.3]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c8\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e7.0\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[6.9, 7.3]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c9\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e10.8\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[10.5, 12.8]\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e2\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e12.2\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[8.4, 13.9]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e0.1\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[0.1, 0.2]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e2.8\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[2.7, 3.8]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e-1.6\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[-1.8, -1.5]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e12.2\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[12.2, 12.6]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c8\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e5.9\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[4.6, 6.2]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c9\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e11.6\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[10.3, 13.0]\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\" morerows=\\\"1\\\" rowspan=\\\"2\\\"\\u003e \\u003cp\\u003eR\\u003csub\\u003emldl\\u003c/sub\\u003e [Ncm]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e1\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e7.4\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[7.1, 7.6]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e0.0\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[-0.4, 0.1]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e1.3\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[1.3, 1.8]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e-1.7\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[-1.7, -1.5]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e5.2\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[4.9, 5.4]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c8\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e4.1\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[3.9, 4.4]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c9\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e6.7\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[6.1, 7.6]\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e2\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e7.0\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[6.1, 7.6]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e-0.5\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[-0.5, -0.3]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e1.6\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[1.4, 2.0]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e-1.7\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[-1.9, -1.5]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c7\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e6.0\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[5.8, 6.5]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c8\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e3.1\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[2.9, 4.1]\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c9\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e6.5\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003e[6.2, 7.8]\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003c/tbody\\u003e \\u003c/colgroup\\u003e \\u003c/table\\u003e\\u003c/div\\u003e \\u003c/p\\u003e \\u003cp\\u003eThe bevG showed the highest ME among all designs tested, it also shows the highest facial crown torque (CT\\u003csub\\u003efacial\\u003c/sub\\u003e) among the designs (39.6 and 40.2 Ncm). Regarding the largest side effect F\\u003csub\\u003efl\\u003c/sub\\u003e, bevG shows lower magnitudes compared to NoAt, recVf, and bevO. Only recV was able to further reduce the side effects of facial force. Although recVfs shows low magnitudes for F\\u003csub\\u003efl\\u003c/sub\\u003e as well, CT\\u003csub\\u003efacial\\u003c/sub\\u003e below 10 N is more than 60% lower compared to all other designs which results in a low ME, shown in Table\\u0026nbsp;\\u003cspan refid=\\\"Tab2\\\" class=\\\"InternalRef\\\"\\u003e2\\u003c/span\\u003e.\\u003c/p\\u003e \\u003c/div\\u003e \\u003cdiv id=\\\"Sec16\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003eEffects on adjacent teeth\\u003c/h2\\u003e \\u003cp\\u003eThe lateral incisor was not the sole recipient of forces and torques; the adjacent teeth also experienced loadings transmitted through the aligner. These neighboring teeth act as anchorage. In most cases, the force and torque equilibrium theory was shown by counterforces in the canine and the central incisor (see Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig3\\\" class=\\\"InternalRef\\\"\\u003e3\\u003c/span\\u003e).\\u003c/p\\u003e \\u003cp\\u003e \\u003c/p\\u003e \\u003c/div\\u003e\"},{\"header\":\"Discussion\",\"content\":\"\\u003cp\\u003eThis study investigated how attachment geometry, vertical position, and composite flash influence the force system generated during facial crown tipping of the maxillary lateral incisor with clear aligners. Among the tested configurations, the gingivally positioned beveled attachment (bevG) produced the highest absolute ME, whereas the rectangular attachment shifted occlusally to mimic a non-fitting aligner (recVfs) showed the lowest ME.\\u003c/p\\u003e \\u003cp\\u003eBecause load transfer in clear aligner mechanics is concentrated at the aligner-attachment contact region (Hong et al. \\u003cspan citationid=\\\"CR13\\\" class=\\\"CitationRef\\\"\\u003e2021\\u003c/span\\u003e), the vertical position of the attachment is expected to affect the resulting force system relative to the tooth\\u0026rsquo;s center of resistance (CoR). Positioning the attachment closer to the estimated center of resistance reduces the effective moment arm of the dominant contact force and may therefore reduce parasitic force components and unintended side effects, while improving the efficiency of the intended tipping response. Although crown pressure distribution was not quantified in this study, the observed differences between bevG and recVfs are consistent with the concept that force application closer to the center of resistance improves ME for facial crown tipping. Indeed, force application at or near CoR is desirable from a clinical efficiency and predictability perspective with this being a goal of orthodontic appliance designs.\\u003c/p\\u003e \\u003cp\\u003eThe addition of composite flash (recVf) decreased the ME compared to the optimal design (recV), underlining the importance of properly placed attachments including the removal of excessive material (Median ME for recV: -4.06 / -4.01 compared to recVf: 2.50 / 2.46). Although, excessive material may be considered as an unavoidable consequence of chairside attachment fabrication, the long term impact on clinical efficiency may be significant. The time and effort to achieve a proper attachment would be a key step towards aligner performance.\\u003c/p\\u003e \\u003cp\\u003eWithin the context of previous work on clear aligner biomechanics, this investigation provides three main contributions. First, it offers an experimental six-degree-of-freedom analysis of facial crown tipping in a maxillary lateral incisor, whereas most prior studies focused on translational movements, primarily in central incisors and molars.(Traversa and Mah \\u003cspan citationid=\\\"CR25\\\" class=\\\"CitationRef\\\"\\u003e2023\\u003c/span\\u003e; Bojrab et al. \\u003cspan citationid=\\\"CR4\\\" class=\\\"CitationRef\\\"\\u003e2024\\u003c/span\\u003e; Alhasyimi et al. \\u003cspan citationid=\\\"CR2\\\" class=\\\"CitationRef\\\"\\u003e2024\\u003c/span\\u003e; Traversa et al. \\u003cspan citationid=\\\"CR24\\\" class=\\\"CitationRef\\\"\\u003e2025\\u003c/span\\u003e; Magura et al. \\u003cspan citationid=\\\"CR20\\\" class=\\\"CitationRef\\\"\\u003e2025\\u003c/span\\u003e; Choi et al. \\u003cspan citationid=\\\"CR7\\\" class=\\\"CitationRef\\\"\\u003e2025\\u003c/span\\u003e) Second, it systematically combines attachment geometry, vertical position, and composite flash, including a clinically realistic non-fitting scenario, within one standardized setup, allowing direct comparison of the resulting movement efficiencies. Third, it reports all six degrees of freedom measured in two sequential test runs enabling the analysis of side effects in more detail. These types of studies are very much lacking as it integrates real-world clinical aspects that impact aligner force application and ultimately performance and efficiency.\\u003c/p\\u003e \\u003cp\\u003eFrom a biomechanical perspective, the rectangular attachment placed centrally (recV) reduced facial force by approximately 60% compared with the NoAt configuration while losing only 16% or less of facial crown torque (CT\\u003csub\\u003efacial\\u003c/sub\\u003e). The centrally placed rectangular attachment yielded a favorable ME (-4.06 and \\u0026minus;\\u0026thinsp;4.01), which can be associated with improved rotational control during tipping movements. The gingivally positioned beveled attachment (bevG) generated the highest facial crown torque (39.6 and 40.2 Ncm) and the most favorable ME (-4.58 and \\u0026minus;\\u0026thinsp;4.42) among all designs. Jones et al. (Jones et al. \\u003cspan citationid=\\\"CR15\\\" class=\\\"CitationRef\\\"\\u003e2009\\u003c/span\\u003e) reported the highest retention for gingivally placed beveled attachments, suggesting that the improved retention may contribute to increased force magnitude due to a tighter aligner fit. A plausible explanation is that the gingivally positioned bevel creates an undercut that enhances aligner retention and force transmission during seating. To the best of our knowledge, this is the first evidence connecting vertical aligner retention and force expression on a single crown, indicating that superior vertical retention may lead to better force expression and therefore more controlled movement. Although the present study is an in-vitro study, it still contributes to the need formulated by Jones et al. (Jones et al. \\u003cspan citationid=\\\"CR15\\\" class=\\\"CitationRef\\\"\\u003e2009\\u003c/span\\u003e). In the present setup, the gap between the gingiva and the attachment appeared sufficient to allow adequate adaptation during thermoforming. However, it is expected that a minimal distance between the ginigva and the attachment must be maintained to allow sufficient aligner adaptation creating a functional attachment. Further studies are needed to confirm whether the mechanical advantage observed here translates directly into improved clinical performance.\\u003c/p\\u003e \\u003cp\\u003eComposite flash (recVf) did not change the facial crown torque compared to the optimal attachment shape (recV) but led to a marked increase in facial force (F\\u003csub\\u003efl\\u003c/sub\\u003e). Mechanically, flash acts as an irregular spacer that disrupts intimate contact between the aligner, the crown surface and the attachment, redistributing contact pressure and amplifying unwanted translational components. This observation is consistent with finite element analysis showing that flash can alter the intended force system and reduce the predictability of tooth movement.(Larson \\u003cspan citationid=\\\"CR17\\\" class=\\\"CitationRef\\\"\\u003e2022\\u003c/span\\u003e) In the present study, the absolute facial force increased by more than 60% when flash was present, supporting previous work suggesting that even minimal flash can substantially intensify side effects.(Larson \\u003cspan citationid=\\\"CR17\\\" class=\\\"CitationRef\\\"\\u003e2022\\u003c/span\\u003e)\\u003c/p\\u003e \\u003cp\\u003eVertical displacement of the attachment, creating a non-fitting aligner (recVfs), also had a pronounced impact on the ME and force system. Occlusally shifting the rectangular attachment resulted in a marked reduction of the facial crown torque, confirming that accurate aligner-attachment fit is essential for predictable tooth movements. Notably, the non-fitting design (recVfs) was the only one tested showing a lower ME in both test runs compared to the design with no attachment (NoAt). Thus, both attachment positioning and the absence of flash are critical to maintaining a high ME and minimizing side effects.\\u003c/p\\u003e \\u003cp\\u003eAdding the information of the forces experienced by the adjacent teeth, it can be seen that most of the counter-forces are emitted by the direct neighbors. In consequence, even if only one tooth has a programmed facial tipping of 3\\u0026deg;, the adjacent teeth are likely to move in the opposite direction. This finding presents the evidence of how complex tooth movements are, especially when they are planned simultaneously. Side effects can potentially be transferred to the full arch making it hard to predict any forces generated on the single tooth. Therefore, an experimental machine such as the OFS is crucial in understanding the interaction between different prescribed tooth movements, especially in combination with auxiliaries such as attachments.\\u003c/p\\u003e \\u003cp\\u003eThe present findings align with and expand previous clinical and experimental data. Jedliński et al. (\\u003cspan citationid=\\\"CR14\\\" class=\\\"CitationRef\\\"\\u003e2023\\u003c/span\\u003e) reported improved orthodontic tooth movement when using attachments; this is supported here by the significant reduction in facial force, mesiodistal torque, and axial rotation observed with the recV design compared with no attachment.\\u003c/p\\u003e \\u003cp\\u003eBased on the results of this study, a gingivally positioned beveled attachment appears most suitable for facial tipping of maxillary lateral incisors, providing an optimal balance between tipping efficacy and control of side effects. In contrast, poorly positioned attachments or those with composite flash may reduce ME by more than 60% (CT\\u003csub\\u003efacial\\u003c/sub\\u003e/F\\u003csub\\u003efl\\u003c/sub\\u003e for bevG: -4.45 and \\u0026minus;\\u0026thinsp;4.51 compared to recVfs: -1.58 and \\u0026minus;\\u0026thinsp;1.73). While use of attachments may be a routine practice, particulary for specific tooth movements, their accurate production and placement are directly linked to aligner performance and the resultant tooth movements. Poorly made and placed attachments may increase the need for refinements, and compromise aligner fit, and potentially contribute to attachment debonding or loss of movement control. Clinicians are therefore encouraged to employ attachment bonding templates designed to limit flash, verify bonding intraorally and, if necessary, clean excessive composite material. Jedliński et al. (\\u003cspan citationid=\\\"CR14\\\" class=\\\"CitationRef\\\"\\u003e2023\\u003c/span\\u003e) further reported that flowable composites or orthodontic bonding composites provide the highest attachment accuracy and durability, which may help clinicians achieve the full biomechanical potential of the prescribed attachment design.\\u003c/p\\u003e \\u003cp\\u003eThe applied methodology has certain limitations which affects the direct translation of the results obtained in this study into a clinical setting. First, the aligners were tested at room temperature where the intraoral temperature is around 37\\u0026deg;C. Second, the Orthodontic Force Simulator is very rigidly designed aiming for high reproducibility, which does not allow the presence of a periodontal ligament (PDL). Additionally, no saliva was present and bone remodelling was not simulated. The higher temperature as well as the presence of the PDL are expected to lower the force magnitude but not the ME of the designs tested, thus the same mechanisms observed in vitro are expected in a clinical setting.\\u003c/p\\u003e \\u003cp\\u003eThe use of the Orthodontic Force Simulator enabled comprehensive vectorial measurement with high reproducibility. The protocol also standardized measurements at 10 seconds to account for viscoelastic relaxation, reflecting the early clinical phase after aligner seating. Where the aligner will relax over time, it is expected that only the force magnitude, but not the ME, will change.\\u003c/p\\u003e \\u003cp\\u003eFuture research should extend this approach to more complex, clinically applied movement patterns and additional tooth types. In practice, planned movements often involve combined translations and rotations, where the management of unwanted side effects becomes even more critical for achieving high movement efficiency. Evaluating different attachment designs and bonding strategies under such combined loading conditions would further bridge the gap between experimental biomechanics and clinical outcomes.\\u003c/p\\u003e\"},{\"header\":\"Conclusions\",\"content\":\"\\u003cp\\u003eWithin the limitations of the orthodontic force simulator setup, gingivally positioned beveled attachments generated the most favorable balance between facial crown torque and its side effects. These mechanical findings suggest that precise attachment placement and flash-free bonding may improve the predictability of facial crown tipping and merit prospective clinical evaluation.\\u003c/p\\u003e \\u003cp\\u003eKey biomechanical findings indicate that:\\u003c/p\\u003e \\u003cp\\u003e \\u003cul\\u003e \\u003cli\\u003e \\u003cp\\u003eAttachments placed as close as possible to the center of resistance increase movement efficiency.\\u003c/p\\u003e \\u003c/li\\u003e \\u003cli\\u003e \\u003cp\\u003eLeaving flash to attachment bases after bonding increases unwanted side effects and leads to less precise OTM.\\u003c/p\\u003e \\u003c/li\\u003e \\u003cli\\u003e \\u003cp\\u003eA vertical mismatch of 1.0 mm between attachment and attachment void in the aligner reduced facial crown torque by more than 60% compared to an optimally placed and shaped attachment.\\u003c/p\\u003e \\u003c/li\\u003e \\u003cli\\u003e \\u003cp\\u003eForce transmission patterns across the dental arch are significantly influenced by attachment positioning, potentially causing undesired effects in adjacent teeth.\\u003c/p\\u003e \\u003c/li\\u003e \\u003c/ul\\u003e \\u003c/p\\u003e\"},{\"header\":\"Abbreviations\",\"content\":\"\\u003cdiv class=\\\"DefinitionList\\\"\\u003e \\u003cdiv class=\\\"DefinitionListEntry\\\"\\u003e \\u003cdiv class=\\\"Term\\\"\\u003eOFS\\u003c/div\\u003e \\u003cdiv class=\\\"Description\\\"\\u003e \\u003cp\\u003eOrthodontic Force Simulator\\u003c/p\\u003e \\u003c/div\\u003e \\u003c/div\\u003e \\u003cdiv class=\\\"DefinitionListEntry\\\"\\u003e \\u003cdiv class=\\\"Term\\\"\\u003eIQR\\u003c/div\\u003e \\u003cdiv class=\\\"Description\\\"\\u003e \\u003cp\\u003eInterquartile range\\u003c/p\\u003e \\u003c/div\\u003e \\u003c/div\\u003e \\u003cdiv class=\\\"DefinitionListEntry\\\"\\u003e \\u003cdiv class=\\\"Term\\\"\\u003eOTM\\u003c/div\\u003e \\u003cdiv class=\\\"Description\\\"\\u003e \\u003cp\\u003eOrthodontic tooth movement\\u003c/p\\u003e \\u003c/div\\u003e \\u003c/div\\u003e \\u003cdiv class=\\\"DefinitionListEntry\\\"\\u003e \\u003cdiv class=\\\"Term\\\"\\u003eCAT\\u003c/div\\u003e \\u003cdiv class=\\\"Description\\\"\\u003e \\u003cp\\u003eClear aligner treatment\\u003c/p\\u003e \\u003c/div\\u003e \\u003c/div\\u003e \\u003cdiv class=\\\"DefinitionListEntry\\\"\\u003e \\u003cdiv class=\\\"Term\\\"\\u003eCoR\\u003c/div\\u003e \\u003cdiv class=\\\"Description\\\"\\u003e \\u003cp\\u003eCenter of resistance\\u003c/p\\u003e \\u003c/div\\u003e \\u003c/div\\u003e \\u003cdiv class=\\\"DefinitionListEntry\\\"\\u003e \\u003cdiv class=\\\"Term\\\"\\u003eME\\u003c/div\\u003e \\u003cdiv class=\\\"Description\\\"\\u003e \\u003cp\\u003eMovement efficiency\\u003c/p\\u003e \\u003c/div\\u003e \\u003c/div\\u003e \\u003cdiv class=\\\"DefinitionListEntry\\\"\\u003e \\u003cdiv class=\\\"Term\\\"\\u003ePDL\\u003c/div\\u003e \\u003cdiv class=\\\"Description\\\"\\u003e \\u003cp\\u003ePeriodontal ligament\\u003c/p\\u003e \\u003c/div\\u003e \\u003c/div\\u003e \\u003c/div\\u003e\"},{\"header\":\"Declarations\",\"content\":\"\\u003cp\\u003e\\u003cstrong\\u003eAcknowledgements\\u003cbr\\u003e\\u0026nbsp;\\u003c/strong\\u003eWe would like to thank Roger Voegtlin for his contributions to this research. As the producer of the custom crown designs, Roger's expertise and meticulous craftsmanship were pivotal in enabling the seamless testing of the different tooth designs.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eStatements and Declarations\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eThe authors declare the following financial interests/personal relationships which may be considered as potential competing interests:\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eFunding\\u003c/strong\\u003e\\u003cbr\\u003e\\u0026nbsp;The materials used in this study were provided by Institut Straumann AG.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eFinancial Interests\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003ePascal Vollenweider: Employee at Institut Straumann AG.\\u003cbr\\u003eFlavio Traversa: Employee at Institut Straumann AG.\\u003cbr\\u003eJames Mah: Paid expert testimony.\\u0026nbsp;\\u003cbr\\u003eMichael de Wild: None\\u003cbr\\u003ePhilippe Chavanne: None\\u003cbr\\u003eAlain Hedinger: Employee at Institut Straumann AG.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eAuthor contributions\\u003c/strong\\u003e\\u003cbr\\u003ePV: Conceptualization, data curation, formal analysis, investigation, methodology, software, visualization, writing – original draft, writing – review and editing\\u003cbr\\u003eFT: Methodology\\u003cbr\\u003eJM: Supervision, writing – review and editing\\u003cbr\\u003eMdW: Supervision\\u003cbr\\u003ePC: Project administration, supervision\\u003cbr\\u003eAH: Resources\\u003c/p\\u003e\\n\\u003ch2\\u003eEthics approval and consent to participate\\u003c/h2\\u003e\\n\\u003cp\\u003eNot applicable.\\u0026nbsp;\\u003c/p\\u003e\\n\\u003ch2\\u003eConsent for publication\\u003c/h2\\u003e\\n\\u003cp\\u003eNot applicable.\\u0026nbsp;\\u003c/p\\u003e\\n\\u003ch2\\u003eAvailability of data\\u003c/h2\\u003e\\n\\u003cp\\u003eAll data supporting the findings of this study are available within the paper.\\u003c/p\\u003e\\n\\u003ch2\\u003eFunding\\u003c/h2\\u003e\\n\\u003cp\\u003eThe used materials were funded by Institut Straumann AG, Switzerland. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.\\u003c/p\\u003e\\n\\u003ch2\\u003eDeclaration of generative AI and AI-assisted technologies in the writing process\\u003c/h2\\u003e\\n\\u003cp\\u003eDuring the preparation of this work the author used ChatGPT to enhance language clarity and style. After using ChatGPT, the author reviewed and edited the content as needed and takes full responsibility for the content of the published article.\\u003c/p\\u003e\"},{\"header\":\"References\",\"content\":\"\\u003col\\u003e\\u003cli\\u003e\\u003cspan\\u003eAbu-Arqub S, Ahmida A, Da Cunha Godoy L, et al (2023) Insight into clear aligner therapy protocols and preferences among members of the American Association of Orthodontists in the United States and Canada. 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Hanser Publishers, Munich Hanser Publications\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eStraumann Group (2025) ClearQuartz. \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003ehttps://www.straumann.com/clearcorrect/de/de/behandler/clearquartz.html\\u003c/span\\u003e\\u003cspan address=\\\"https://www.straumann.com/clearcorrect/de/de/behandler/clearquartz.html\\\" targettype=\\\"URL\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e. Accessed 24 Apr 2026\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eTraversa F, Chavanne P, Mah J (2025) Biomechanics of clear aligner therapy: Assessing the influence of tooth position and flat trimline height in translational movements. Orthod Craniofac Res 28:1\\u0026ndash;11. \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003ehttps://doi.org/10.1111/ocr.12796\\u003c/span\\u003e\\u003cspan address=\\\"10.1111/ocr.12796\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eTraversa F, Mah J (2023) Impact of buccopalatal translation and trimline design on clear aligners: An in vitro study of the maxillary right central incisor. J Aligner Orthod 7:1\\u0026ndash;10\\u003c/span\\u003e\\u003c/li\\u003e\\u003c/ol\\u003e\"},{\"header\":\"Table 2\",\"content\":\"\\u003cp\\u003eTable 2 is available in the Supplementary Files section.\\u003c/p\\u003e\"}],\"fulltextSource\":\"\",\"fullText\":\"\",\"funders\":[],\"hasAdminPriorityOnWorkflow\":false,\"hasManuscriptDocX\":true,\"hasOptedInToPreprint\":true,\"hasPassedJournalQc\":\"\",\"hasAnyPriority\":false,\"hideJournal\":false,\"highlight\":\"\",\"institution\":\"\",\"isAcceptedByJournal\":false,\"isAuthorSuppliedPdf\":false,\"isDeskRejected\":\"\",\"isHiddenFromSearch\":false,\"isInQc\":false,\"isInWorkflow\":false,\"isPdf\":false,\"isPdfUpToDate\":true,\"isWithdrawnOrRetracted\":false,\"journal\":{\"display\":true,\"email\":\"info@researchsquare.com\",\"identity\":\"digital-and-aligner-orthodontics\",\"isNatureJournal\":false,\"hasQc\":true,\"allowDirectSubmit\":false,\"externalIdentity\":\"\",\"sideBox\":\"Learn more about [Digital and Aligner Orthodontics](https://link.springer.com/journal/44525)\",\"snPcode\":\"44525\",\"submissionUrl\":\"https://submission.springernature.com/new-submission/44525/3\",\"title\":\"Digital and Aligner Orthodontics\",\"twitterHandle\":\"\",\"acdcEnabled\":true,\"dfaEnabled\":true,\"editorialSystem\":\"stoa\",\"reportingPortfolio\":\"Springer Open\",\"inReviewEnabled\":true,\"inReviewRevisionsEnabled\":true},\"keywords\":\"Orthodontic Appliances, Removable\",\"lastPublishedDoi\":\"10.21203/rs.3.rs-9517209/v1\",\"lastPublishedDoiUrl\":\"https://doi.org/10.21203/rs.3.rs-9517209/v1\",\"license\":{\"name\":\"CC BY 4.0\",\"url\":\"https://creativecommons.org/licenses/by/4.0/\"},\"manuscriptAbstract\":\"\\u003ch2\\u003ePurpose\\u003c/h2\\u003e \\u003cp\\u003eTo evaluate how attachment geometry, vertical positioning, and composite flash influence the biomechanics of facial crown tipping in clear aligner therapy (CAT).\\u003c/p\\u003e\\u003ch2\\u003eMethods\\u003c/h2\\u003e \\u003cp\\u003eSeven attachment configurations were tested on the Orthodontic Force Simulator (OFS): No attachment (NoAt), vertical rectangular attachment including central (recV), with flash (recVf), and occlusally shifted with flash (recVfs) as well as beveled designs with central (bevC), occlusal (bevO), and gingival (bevG) positioning. Thirty-five ClearQuartz\\u0026trade; aligners were thermoformed and loaded under a 3\\u0026deg; facial tipping protocol. The primary outcome was the movement efficiency (ME, facial crown torque divided by facial force). Force and torque data are reported in addition for a better understanding of the side effects created by the designs. The normality of the data was analyzed with the Shapiro-Wilk and the Kolmogorov\\u0026ndash;Smirnov test, and the Mann\\u0026ndash;Whitney U test was applied due to non-normality.\\u003c/p\\u003e\\u003ch2\\u003eResults\\u003c/h2\\u003e \\u003cp\\u003eAll designs tested revealed significant different movement efficiencies. The beveled attachment placed close to the gingival margin generated the highest median absolute ME (-4.45 and \\u0026minus;\\u0026thinsp;4.51) as well as the highest facial crown torque (39.6 N, 40.2 N) for both test rounds. All attachment designs with attachments showed a higher ME compared to the crown design without any attachment except recVfs (recVfs: -1.58, -1.73; NoAt: -1.88, -1.89).\\u003c/p\\u003e\\u003ch2\\u003eConclusions\\u003c/h2\\u003e \\u003cp\\u003eAttachment geometry, vertical displacement, and composite flash significantly influence aligner biomechanics. Placing an attachment as close as possible to the center of resistance as well as ensure its proper shape and position increase movement efficiency.\\u003c/p\\u003e\",\"manuscriptTitle\":\"Improving Facial Crown Tipping with Clear Aligners: the role of attachment design and composite flash\",\"msid\":\"\",\"msnumber\":\"\",\"nonDraftVersions\":[{\"code\":1,\"date\":\"2026-05-15 10:02:35\",\"doi\":\"10.21203/rs.3.rs-9517209/v1\",\"editorialEvents\":[{\"type\":\"communityComments\",\"content\":0},{\"type\":\"editorInvitedReview\",\"content\":\"\",\"date\":\"2026-05-18T10:43:25+00:00\",\"index\":\"hide\",\"fulltext\":\"\"},{\"type\":\"reviewerAgreed\",\"content\":\"165502092639826791515984558864887355099\",\"date\":\"2026-05-11T00:42:06+00:00\",\"index\":\"hide\",\"fulltext\":\"\"},{\"type\":\"reviewerAgreed\",\"content\":\"13751702728413076845131866052233167952\",\"date\":\"2026-05-06T15:13:48+00:00\",\"index\":\"hide\",\"fulltext\":\"\"},{\"type\":\"reviewersInvited\",\"content\":\"\",\"date\":\"2026-05-06T15:09:45+00:00\",\"index\":\"\",\"fulltext\":\"\"},{\"type\":\"editorAssigned\",\"content\":\"\",\"date\":\"2026-04-30T12:32:56+00:00\",\"index\":\"\",\"fulltext\":\"\"},{\"type\":\"checksComplete\",\"content\":\"\",\"date\":\"2026-04-30T12:32:11+00:00\",\"index\":\"\",\"fulltext\":\"\"},{\"type\":\"submitted\",\"content\":\"Digital and Aligner Orthodontics\",\"date\":\"2026-04-24T12:13:53+00:00\",\"index\":\"\",\"fulltext\":\"\"}],\"status\":\"published\",\"journal\":{\"display\":true,\"email\":\"info@researchsquare.com\",\"identity\":\"digital-and-aligner-orthodontics\",\"isNatureJournal\":false,\"hasQc\":true,\"allowDirectSubmit\":false,\"externalIdentity\":\"\",\"sideBox\":\"Learn more about [Digital and Aligner Orthodontics](https://link.springer.com/journal/44525)\",\"snPcode\":\"44525\",\"submissionUrl\":\"https://submission.springernature.com/new-submission/44525/3\",\"title\":\"Digital and Aligner Orthodontics\",\"twitterHandle\":\"\",\"acdcEnabled\":true,\"dfaEnabled\":true,\"editorialSystem\":\"stoa\",\"reportingPortfolio\":\"Springer Open\",\"inReviewEnabled\":true,\"inReviewRevisionsEnabled\":true}}],\"origin\":\"\",\"ownerIdentity\":\"2b76f76e-ce3e-4467-8bde-8b1b3a783611\",\"owner\":[],\"postedDate\":\"May 15th, 2026\",\"published\":true,\"recentEditorialEvents\":[{\"type\":\"editorInvitedReview\",\"content\":\"\",\"date\":\"2026-05-18T10:43:25+00:00\",\"index\":14,\"fulltext\":\"\"},{\"type\":\"reviewerAgreed\",\"content\":\"165502092639826791515984558864887355099\",\"date\":\"2026-05-11T00:42:06+00:00\",\"index\":13,\"fulltext\":\"\"},{\"type\":\"reviewerAgreed\",\"content\":\"13751702728413076845131866052233167952\",\"date\":\"2026-05-06T15:13:48+00:00\",\"index\":11,\"fulltext\":\"\"},{\"type\":\"reviewersInvited\",\"content\":\"3\",\"date\":\"2026-05-06T15:09:45+00:00\",\"index\":\"\",\"fulltext\":\"\"},{\"type\":\"editorAssigned\",\"content\":\"\",\"date\":\"2026-04-30T12:32:56+00:00\",\"index\":\"\",\"fulltext\":\"\"},{\"type\":\"checksComplete\",\"content\":\"\",\"date\":\"2026-04-30T12:32:11+00:00\",\"index\":\"\",\"fulltext\":\"\"}],\"rejectedJournal\":[],\"revision\":\"\",\"amendment\":\"\",\"status\":\"under-review\",\"subjectAreas\":[],\"tags\":[],\"updatedAt\":\"2026-05-15T10:02:35+00:00\",\"versionOfRecord\":[],\"versionCreatedAt\":\"2026-05-15 10:02:35\",\"video\":\"\",\"vorDoi\":\"\",\"vorDoiUrl\":\"\",\"workflowStages\":[]},\"version\":\"v1\",\"identity\":\"rs-9517209\",\"journalConfig\":\"researchsquare\"},\"__N_SSP\":true},\"page\":\"/article/[identity]/[[...version]]\",\"query\":{\"redirect\":\"/article/rs-9517209\",\"identity\":\"rs-9517209\",\"version\":[\"v1\"]},\"buildId\":\"XKTyCvWXoU3ODBz1xrDgd\",\"isFallback\":false,\"isExperimentalCompile\":false,\"dynamicIds\":[84888],\"gssp\":true,\"scriptLoader\":[]}","source_license":"CC-BY-4.0","license_restricted":false}