Objective: This study aimed to evaluate the effects of attachment design on maxillary molar distalization and simultaneous expansion during distalization, and the influence of third molars on distalization in the clear aligner technique using the finite element method. Methods: Six models were created to evaluate three different attachment designs on the second molars. Model I: employed a vertical rectangular attachment; Model II: used a vertical rectangular attachment with the presence of the third molar; Model III: used a combined semi-elliptical attachment; and Model IV: featured an opposed semi-elliptical attachment with buccal and palatal components. Models I through IV focused on distalization.Models V and VI were created by adding expansions to Models III and IV. The displacement amounts, clear aligner deformations, and stress distributions were analyzed using Ansys 19.2. Results: The presence of a third molar reduced maximum total displacement by 17%. Models I and III demonstrated similar distal displacement and tipping, both of which were more pronounced than in Model IV. Model IV achieved the most parallel tooth movement, with the least distal and buccal tipping and minimal distopalatal rotation. In the comparison of Models V and VI, Model VI exhibited greater distal and buccal displacements and more tipping than Model V. Conclusions The presence of a third molar reduced distalization efficiency and increased clear aligner deformation. For both movements, the attachment that provided the most parallel movement showed the least displacement. When selecting attachments, it is essential to consider factors such as tooth rotation, inclination, bone support, and root health.

Objective: The effect of different attachment positions on torque control during the labialization of maxillary lateral incisors with clear aligners was evaluated using finite element analysis. Methods: Anatomical data acquired through cone-beam computed tomography, combined with the design of 0.625-mmthick aligners and horizontal attachments, were integrated into the software. Six distinct simulations were generated: (1) attachment-free, (2) labial attachment placed gingivally, (3) labial attachment placed mid-crown, (4) labial attachment placed incisally, (5) palatal attachment, and (6) attachment placed labially and palatally. The evaluation was performed using a default aligner activation of 0.25 mm. Results: The crown of the lateral incisor demonstrated labial movement, while the root exhibited palatal movement in all models. Group 6 showed the lowest crown and root displacements on both axes, whereas the attachmentfree group exhibited the greatest crown movement. The aligner experienced maximum deformation at the incisal edge, with deformation progressively decreasing towards the gingival region. Group 6 demonstrated the least deformation of all groups. The Von Mises stresses in the periodontal ligament (PDL) were most pronounced at the gingival level, with higher values on the palatal side than on the labial side. Conclusions The use of attachments, particularly the combination of labial and palatal attachments, enables a more precise labialization process, helping to reduce tipping. Increasing crown movement of the lateral incisor elevates stress within the PDL, with the highest stress observed in the palatal region at the gingival level.

Objective: To evaluate the ideal anteroposterior position of incisors in lateral smiling profiles with different chin prominences and to relate these positions to nose and chin landmarks based on the perceptions of orthodontists and laypersons. Methods: A lateral smiling profile image of a female subject was adjusted to create five levels of chin prominence (–6, –3, 0, +3, +6 mm). For each level, the anteroposterior positions of the maxillary incisors were adjusted across five positions (–4, –2, 0, +2, +4 mm). Thirty-six orthodontists and 36 laypersons rated the attractiveness of each profile using a visual analog scale. The maxillary incisor position (U1) was measured relative to the external nose and chin landmarks (E-lines). Differences in perceptions between orthodontists and laypersons were analyzed. Results: For profiles with 6 and 3 mm chin retrusion, the most favored incisor positions were the 2 mm retrusion and unaltered positions, respectively. For the unaltered chin prominence, orthodontists preferred unaltered incisors, while laypersons favored 2 mm protrusion.Conversely, for 3 and 6 mm chin protrusion, both groups preferred 4 and 2 mm protrusion, respectively. The distance between U1 and the E-line is the most attractive images ranged from 8.5 to 11.5 mm. Based on the regression model, an optimal U1-E-line distance of 8.95 mm was recommended. Conclusions The preferred incisor position is influenced by chin prominence, with the incisor position shifting in the same direction as the chin. The U1 E-line can be a useful clinical tool for determining the proper incisor positioning. Esthetic perceptions were generally consistent between orthodontists and laypersons.

Objective: This study aimed to compare the accuracy of Qlone, Magiscan, and 3dMD with that of direct anthropometry (DA). Methods: The study involved 41 patients. Sixteen facial landmarks, including six individual and five paired points, were marked on each participant’s face. Subsequently, 18 linear measurements were assessed using a 3dMD device (multicamera photogrammetry), Qlone, Magiscan smartphone applications (single-camera photogrammetry), and DA.The Qlone and Magiscan images were calibrated using a reference point 10 mm from the nasion during DA to ensure a 1:1 correspondence. Results: Concerning the precision of the digital methods compared to DA, the mean intraclass correlation coefficient values of 3dMD, Qlone and Magiscan were 0.989, 0.980 and 0.982, respectively. Compared with DA, 3dMD achieved excellent trueness with the lowest average absolute differences in the measurements (highest value = 0.95 ± 0.62 mm). The highest values for Qlone and Magiscan were 1.51 ± 1.11 mm and 2.14 ± 1.69 mm, respectively. According to the number of parameters, the ranking of unreliable values (> 2 mm) was Magiscan (n = 46), Qlone (n = 35), and then, 3dMD (n = 4). Furthermore, reliability (less than 1 mm) was the highest for 3dMD (n = 517), followed by Magiscan (n = 457), and then, Qlone (n = 415). Conclusions The 3dMD achieved excellent trueness with the lowest average absolute differences in the measurements. Based on statistical analysis, the trueness values of Magiscan and Qlone were close to that of 3dMD. To apply these smartphone applications clinically, more studies are necessary.

Objective: Miniscrews are commonly utilized as temporary anchorage devices (TADs) in cases of maxillary protrusion and premolar extraction. This study aimed to investigate the effects and potential side effects of two conventional miniscrew configurations on the maxillary incisors. Methods: Eighty-two adult patients with maxillary dentoalveolar protrusion who had undergone bilateral first premolar extraction were retrospectively divided into three groups: non-TAD, two posterior miniscrews only (P-TADs), and two anterior and two posterior miniscrews combined (AP-TADs). Cone-beam computed tomography was used to evaluate the maxillary central incisors (U1). Results: The APTADs group had significantly greater U1 intrusion (1.99 ± 2.37 mm, n = 50) and less retroclination (1.70° ± 8.80°) compared to the P-TADs (–0.07 ± 1.65 mm and 9.45° ± 10.68°, n = 60) and non-TAD group (0.30 ± 1.61 mm and 1.91° ± 9.39°, n = 54).However, the AP-TADs group suffered from significantly greater apical root resorption (ARR) of U1 (2.69 ± 1.38 mm) than the P-TADs (1.63 ± 1.46 mm) and non-TAD group (0.89 ± 0.97 mm). Notably, the incidence of grade IV ARR was 16.6% in the AP-TADs group, significantly higher than the rates observed in the P-TADs (6.7%) and non-TAD (1.9%) groups. Multiple regression analysis revealed that after excluding tooth movement factors, the AP-TADs configuration resulted in an additional 0.5 mm of ARR compared with the P-TADs group. Conclusions In cases of maxillary protrusion and premolar extraction, the use of combined anterior and posterior miniscrews enhances incisor intrusion and minimizes torque loss of the maxillary incisors. However, this approach results in more severe ARR, likely due to the increased apical movement and composite force exerted.

Objective: To study the influence of bracket base meshes on shear bond strength and observe them using a scanning electron microscopy (SEM) before and after debonding. Methods: Ninety brackets were divided into nine groups of 10 samples each: G1-Alexander, G2-Mini Sprint® Brackets, G3-In-Ovation R CCO,  G4-Gemini SL Self-Ligating Bracket, G5-Classic mini 2G Stylus® , G6-Gemini Metal Brackets, G7-ClarityTM Advanced, G8-Crystall-Ize® , and G9-Ceramic Series Flexx 2G® . Groups G1 to G6 and G7 to G9 consisted of metallic and aesthetic brackets, respectively. Initial photographs of all brackets were taken through SEM at 25X magnification. The brackets were then bonded to premolars using TransbondTM XT, and a shear bond strength test was conducted after 24 hours using an Instron machine at 1 mm/min. After debonding, the bracket meshes were observed using SEM. Results: Before bonding, 72.22% of brackets didn’t present mesh defects, while 27.77% did. SEM analysis revealed that G4 and G5 presented defects in 100%, G7 in 40%, and G8 in 10%. The average shear bond strength of 9.67 ± 2.84 MPa and 11.21 ± 4.99 MPa were obtained for both metallic and aesthetic brackets, respectively. A Pairwise–Wilcoxon test with Benjamini–Hochberg correction was conducted to determine specific statistical differences between the groups, revealing significant differences based on bracket type and shear bond strength (P < 0.009). Conclusions This study suggested that the shape of bracket meshes influenced shear bond strength.

Objective: This study aimed to evaluate bone remodeling in gingival crevicular fluid (GCF) during canine distalization in obese individuals and compare it to that in normal-weight individuals. Additionally, the orthodontic tooth movement rates of obese individuals were measured and compared with those of normalweight individuals. Methods: Thirty-six patients (18 obese and 18 normalweight) aged 12–18 years who were candidates for maxillary first premolar extraction for Angle Class II malocclusion were included in the study. The two groups were formed according to World Health Organization guidelines. A normal-weight group (body mass index [BMI] 16–85%) and an obese group (BMI ≥ 95%). Gingival crevicular fluid samples were collected before, 24 hours after, and on the 7th, 14th, and 21st days after the application of the distalization force. Enzyme-linked immunosorbent assay was used to measure leptin, receptor activator of nuclear factor kappa-Β ligand (RANKL), osteoprotegerin (OPG) and interleukin-6 (IL-6) levels in GCF samples. In addition to the recorded GCF sampling times, the amount of canine tooth movement was calculated using digital models obtained on the 28th day and 3rd month. Results: Leptin, RANKL, OPG, and IL-6 levels were significantly higher in the obese group (P < 0.05). The digital model measurements displayed high rates of repeatability (ICC 0.990). The difference in the amount of tooth movement between groups was not statistically significant (P > 0.05). Conclusions Although obese and normal-weight individuals showed different biomarker levels during tooth movement, there were no significant differences in the amount of movement.

Objective: Extraction of the mandibular second molar (L7) and substitution by the mandibular third molar (L8) is an effective treatment option. This study aimed to evaluate spontaneously erupted L8 occlusion after L7 extraction, and identify the influencing factors. Methods: This study assessed 46 L8 from 28 patients using dental study models, panoramic radiographs, and lateral cephalograms obtained during L7 extraction (T1) and completion of L8 eruption (T2). At T2, samples were categorized as acceptable (A-group) or unacceptable (U-group) based on the American Board of Orthodontics index.L8 angulation and position, retromolar space, distance between the Xi point and mandibular first molar (L6), and Nolla stage were compared between the groups to identify the predictive factors for successful eruption. Results: At T2, 58.7% of L8 exhibited acceptable occlusion. Age at T1 was significantly higher in the U-group than that in the A-group. Angles ∠6-MnP and ∠8-MnP differed significantly between the groups at T2. Xi-L6 distance was considerably longer in the A-group than that in the U-group at T1 and T2. Younger age at extraction and Xi-L6 distance at T1 affected the acceptable occlusion. Conclusions Younger age at L7 extraction and adequate eruption space (Xi-L6 distance) appear to be the key factors for achieving acceptable L8 occlusion.

Objective: The treatment of asymmetric maxillary hypoplasia and dental crowding secondary to unilateral cleft lip and palate (UCLP) is often challenging.This study introduced an asymmetric tooth-borne distractor in anterior maxillary segmental distraction osteogenesis and used three-dimensional finite element analysis to evaluate its potential for clinical application in cases of asymmetrical maxillary hypoplasia. Methods: A cone-beam computed tomography scan of a late adolescent with UCLP was used to construct a three-dimensional finite element model of the teeth and maxillary structures. An asymmetric distractor model was used to simulate conventional distraction osteogenesis and asymmetric distraction osteogenesis (ADO) to evaluate the resultant stress distribution and displacement. Results: Postoperatively, both distraction methods resulted in anterior maxillary segment advancement with a slight upward movement. ADO yielded a greater increase in the dental arch length on the cleft side and induced rotation of the anterior maxillary segment, potentially improving midline deviation. Both methods showed similar stress distributions, with higher stress concentrations on the cleft side. Conclusions ADO may offer clinical advantages in correcting asymmetrical maxillary hypoplasia in patients with UCLP by facilitating asymmetrical expansion and rotation of the maxilla. Further research is needed to generalize these findings to other clinical presentations.