Objective: This study aimed to investigate the prevalence and characteristics of impacted teeth (ITs) in orthodontic patients at university dental hospitals in Korea. Methods: This study included 14,774 patients who visited the Department of Orthodontics at 10 university dental hospitals in Korea between 2020 and 2022 and underwent orthodontic diagnosis. The prevalence and characteristics of ITs were investigated using orthodontic diagnostic records, radiographs, and diagnostic casts. Results: The prevalence of ITs, excluding third molar impaction, in Korean orthodontic patients was 13.6% (n = 2,014).The prevalence of ITs in pediatric orthodontic patients was 24.5% (n = 1,614).Of these patients, 68.2% had one IT, 27.5% had two ITs, 24.3% had bilateral IT, and 75.7% had unilateral IT. The most frequent IT was the maxillary canine (50.1%), followed by the mandibular second molar (11.7%), and maxillary second premolar (9.6%). An abnormal eruption path (46.5%) was the most frequent etiology. Orthodontic traction after surgical exposure (70.6%) was the most frequent treatment option. Among the patients with ITs, 29.8% had other dental anomalies, such as tooth agenesis (8.7%), microdontia (8.0%), and supernumerary teeth (5.1%). Furthermore, 50.8% had complications such as cystic lesions (18.3%), transposition (17.7%), and root resorption (14.8%).Among the patients with maxillary canine impaction, 62.2% had labial maxillary canine impaction and 21.1% had palatal maxillary canine impaction. Conclusions The prevalence of ITs in Korean orthodontic patients at university dental hospitals was high, particularly in pediatric orthodontic patients.

Objective: To propose the utilization of virtual tooth models (VTMs) created by combining tooth root data from cone-beam computed tomography (CBCT) and crown data gathered through intraoral scanning to assess inter-root distance and angulation during orthodontic treatment when repeated radiographic monitoring becomes necessary. Methods: Patients with planned dental implant placement in edentulous areas during or after orthodontic treatment and who underwent intraoral and CBCT scans at the pretreatment and posttreatment stages were selected. Tooth models were fabricated by merging intraorally scanned crowns with the corresponding CBCT-scanned roots from the pretreatment. Tooth positions posttreatment was estimated by integrating models into posttreatment intraoral scans. Moreover, the actual positions were obtained from posttreatment CBCTs. Discrepancies in the estimated and actual tooth positions, including interradicular distances and inter-root angulations, were compared. Results: The minimum inter-radicular distance between two adjacent teeth demonstrated no significant difference between the estimated and actual tooth positions. The difference in inter-root angulation was not statistically significant. Most interradicular distances measured at each landmark revealed no significant differences between the estimated and actual tooth positions, except at the buccolingual midpoint of the cemento-enamel junction, where a slight discrepancy was observed. Conclusions The tooth position of VTMs demonstrated clinically acceptable accuracy compared to CBCT scans. Additionally, VTMs can benefit both clinicians and patients by enabling accurate assessment of the inter-radicular space for dental implant placement without repeated CBCT scans.

Objective: To assess the success rate and proximity of miniscrews to the root using surgical guides produced by integrating data obtained from conebeam computed tomography and intraoral scanned models. Methods: This retrospective study involved 113 patients (224 miniscrews) who underwent miniscrew placement as part of their orthodontic treatment. Two operators placed miniscrews between the buccal alveolar bone of each patient and assessed initial stability by measuring the Periotest value (PTV) and insertion torque (IT). Patients were divided into two groups based on the miniscrew insertion method: manual group (MG) and surgical guide group (SG). Root proximity was assessed using periapical radiography, and miniscrews that remained in place for over 6 months were considered successful. Results: There was a statistically significant difference in the Kaplan–Meier survival curves between the groups (P < 0.05). The success rates of the miniscrews were 79.1% and 90.5% for the MG and SG, respectively (P < 0.05). The root contact rate also differed significantly between the groups (MG, 17.5%; SG, 0.1%; P < 0.001). However, the PTV and IT did not show significant differences between the groups. Conclusions Proximity to the root and utilization of surgical guides have the most direct impact on the success rate of miniscrews. Root proximity can be effectively reduced using surgical guides. Therefore, the use of a miniscrew surgical guide is recommended to increase the success rate of miniscrews as stable anchorage devices, particularly in cases with narrow interradicular space.

Objective: Using finite element method (FEM) analysis of a clear aligner (CA), this study aimed to investigate the effects of varying the edentulous space on canine distal bodily movement during space closure following maxillary first premolar extraction. Methods: FEM analysis was used to simulate distal canine bodily movement following maxillary first premolar extraction using CAs. Four CA designs for edentulous spaces were compared: no-pontic, full-pontic, halfpontic, and beam. Three-dimensional models of the tooth components and CA were created. The target was set at a 0.25-mm distal canine movement. Long-term tooth movement was simulated using an iterative calculation method. Results: All the groups initially showed crown displacement, distal tipping, and distal rotation.Over time, the movement patterns differed in relation to the design. The no-pontic design exhibited the greatest displacement and tipping. The beam design exhibited the largest initial displacement but showed the lowest displacement and tipping thereafter. Full- and half-pontic designs yielded intermediate results. Significant force reduction was observed immediately after CA application, and was followed by a gradual decrease. The mean tooth-movement achievement rate was approximately 76.7%. Conclusions The edentulous space design of the CA substantially affected tooth-movement behavior. An iterative simulation is necessary to evaluate longterm tooth-movement patterns. The beam design demonstrated optimal suitability for bodily movement with minimal tipping. For optimal results, additional setup or overcorrection may be necessary.

Objective: Temporary anchorage devices (TADs) have considerably reduced the need for anterior segmental osteotomy (ASO) in patients with Class I malocclusion. Most previous studies have been published before the widespread use of TADs, thus warranting new guidelines for determining the optimal approach for surgery and orthodontic treatment. This study aimed to establish guidelines on the choice between ASO and non-ASO (NASO) based on soft tissue considerations. Methods: Sixty-seven patients diagnosed with skeletal Class II malocclusion were divided into the ASO (n = 31) and NASO (n = 36) groups. Cephalometric analyses were used to compare the initial and final records to assess the effect of treatment on soft tissues. The interlabial gap, upper lip anterior to the E-line, lower lip anterior to the E-line, H-angle, upper lip to the nasion-perpendicular line, and nasolabial angle were evaluated. In particular, a proportional difference indicator between the upper and lower lips relative to the pogonion angle between the facial plane and CK line was presented, followed by statistics analyses. Statistical significance was set at P < 0.05. Results: Both groups demonstrated normal proportions of the upper and lower lips; however, significant differences favoring ASO over NASO in terms of soft tissue changes were observed for several variables. Conclusions ASO is advised if the required adjustment for the upper and lower lips is –4.0 mm and –5.0 mm, respectively. For modifications of –2.0 mm, NASO is preferred. This study provides clinical guidelines on the choice between ASO and NASO based on the required lip movement measurements.

Objective: To quantitatively analyze and compare the forces and moments generated by thermoformed polyethylene terephthalate glycol (PETG) and direct-printed TC-85 clear aligners (CAs), with various margin designs, during premolar rotation. Methods: In total, 132 CAs were fabricated and divided into four groups (n = 33 per group). Group C consisted of thermoformed PETG aligners with a 2 mm gingival margin. Group E comprised direct-printed TC-85 aligners with equi-gingival margin, whereas Group G utilized direct-printed TC-85 aligners with 2 mm gingival margins.Finally, Group T featured direct-printed TC-85 aligners with an additional 1 mm thickness at the mesial embrasure. The forces and moments were measured using a 6-axis force/moment transducer at 2°, 3°, and 4° of rotation. All measurements were conducted at 37°C to simulate intraoral conditions. Forces were measured in the buccolingual, anteroposterior, and vertical directions, while moments were measured in the mesiodistal, buccolingual, and rotational planes. Results: The PETG aligners (Group C) showed significantly increased buccal and posterior force across the rotation angles (P < 0.05), whereas the intrusive force remained consistent. In contrast, the TC-85 aligners maintained consistent forces across all rotation angles.Direct-printed aligners demonstrated significantly lower intrusive forces than PETG aligners (P < 0.001). Group T exhibited reduced unwanted forces while maintaining effective rotational moments. Furthermore, all direct-printed aligners showed more predictable force delivery patterns than thermoformed aligners. Conclusions Direct-printed TC-85 aligners demonstrated superior force consistency and reduced unwanted side effects compared with traditional PETG aligners. Although marginal design modifications did not significantly improve rotational efficiency, they effectively reduced unwanted intrusive forces.

Objective: Considering the success of infrazygomatic mini-implants in conjunction with traditional braces, this study aimed to evaluate the efficacy of infrazygomatic mini-implants in en masse maxillary distalization utilizing clear aligner therapy. Methods: In a three-dimensional finite element study, we evaluated the en masse maxillary dental distalization through the use of infrazygomatic mini-implants equipped with varying force-application arm lengths (0 mm, 4 mm, and 8 mm). Vertical, sagittal, and horizontal displacements were quantified. Results: Intrusion was observed in the incisors at all force application arm lengths (0 mm, 4 mm, and 8 mm), with similar sagittal displacement tendencies and labial crown tipping. Among all maxillary teeth, only the canine exhibited distalization of both the crown and root. Distalization of the posterior teeth was achieved, with the greatest magnitude of distalization occurring at the 0-mm force application arm length, which was characterized by minimal tipping and reduced vertical movements compared to the other force application arm lengths. Conclusions The findings indicate that infrazygomatic mini-implants represent a viable approach for facilitating targeted tooth movement in clear aligners across various force-application arm lengths. These results may inform orthodontic treatment strategies in non-extraction cases.

Objective: Several studies have highlighted the toxic potential of bisphenol A (BPA), however, BPA release from orthopedic devices remains poorly investigated.Therefore, this study aimed to evaluate BPA levels in the saliva of children treated using Haas expanders. Methods: Twenty-two children of both sexes aged 6–10 years who required rapid maxillary expansion were recruited. One week after placement of elastics to separate the permanent molars, orthodontic bands were adapted, and maxillary impressions were obtained using alginate impression material. Haas expanders were fabricated using a standardized amount of acrylic resin. The bands were cemented using Transbond Plus Light Cure Band (3M).Saliva samples were collected at five time points: before (T0) and 30 minutes (T1), 24 hours (T2), 1 week (T3), and 1 month (T4) after Haas expander installation.BPA levels were measured using ultra-high-performance liquid chromatography coupled with Tandem Mass Spectrometry. The results were evaluated using oneway analysis of variance with Tukey’s post-hoc test (alpha = 5%). Results: BPA levels were below the recommended tolerable daily intake (TDI) at all timepoints;however, salivary BPA levels at T1 (70.324 ng/mL ± 37.05) and at T2 (18.015 ng/mL ± 11.22) were significantly higher compared to that at T0 (0.475 ng/mL ± 0.27) (P < 0.05). Conclusions Salivary BPA levels significantly increased 30 minutes and 24 hours after Haas expander installation and return to baseline values after 1 week. BPA levels did not exceed the TDI, suggesting that the use of Haas expanders may be considered safe concerning BPA exposure in children.

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.