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Background The traction of an impacted canine is complicated and challenging due to its position, direction, relationship to adjacent teeth and anchorage design. This study describes a customized device for the three-dimensional traction of complex maxillary impacted canines (MICs). Case presentation This article reports two cases of young patients with complex MICs (Case Ⅰ: the MIC has high horizontal impaction without enough adjacent anchorage teeth, and Case II: the crown of the MIC is entirely embedded between the roots of adjacent incisors). A digitally customized device was developed to optimally resolve impaction management challenge in both patients. The therapeutic effects are evaluated by comparing the pretreatment, during-treatment and posttreatment results, including those from clinical and imaging examinations. After traction using the customized device, the impacted canines were successfully repositioned in the dental arch, and both the anchoring teeth and adjacent teeth were in good condition, which established a robust foundation for subsequent stage. Then, after fixed orthodontic treatment, both patients exhibited good dental alignment. Conclusions The satisfactory clinical outcome demonstrated that the customized device is convenient, comfortable, safe, and excellent in 3D control for the traction of MIC; in conjunction with fixed orthodontic techniques, it can effectively accomplish comprehensive orthodontic treatment for MIC.

Objective This study aimed to analyze the stress distribution in the dentoalveolar structures of a labially impacted dilacerated maxillary central incisor during orthodontic traction, considering different positions of the traction button on the tooth’s crown through finite element analysis (FEA). Materials and methods Four three-dimensional (3D)finite element models (FEM) were created to simulate the maxilla of a 9-year-old female patient, featuring a left labially impacted dilacerated maxillary central incisor with the only variation being the position of the orthodontic traction button: at the incisal third of the labial surface (Model A), at the incisal third of the palatal surface (Model B), at the middle third of the palatal surface (Model C), and the cervical third of the palatal surface (Model D). Material parameters, grids, boundary conditions, coordinate systems, and load conditions were set in Ansys to establish the FEM for traction of the impacted incisor. A 100 g total traction force was applied between the button and a 0.016 × 0.022-inch stainless steel archwire in the direction perpendicular to the impacted tooth’s crown. The initial tooth displacements, biomechanical stress at the root apex, alveolar bone von Mises stress, and hydrostatic stress of the periodontal ligament (PDL) under the four conditions were analyzed and compared. Results The impact of traction button positioning on tooth displacement, stress distribution, and bone loading was assessed in four models. Model B demonstrated the highest labiopalatal and vertical displacement. The stress concentrations in the impacted tooth’s root were highest in model B, particularly in the cervical region labially, while model D showed the lowest root stress. Maximum stress in the alveolar bone was also observed in models A and B, particularly on the palatal surface near the cervical region. Hydrostatic stress in the periodontal ligament was highest in model B and lowest in model D. Conclusion The traction button positioned on the incisal third of the labial or palatal surface facilitates significant tooth movement. Still, it carries a higher risk of periodontal ligament damage, root and alveolar bone resorption. In contrast, the traction button positioned on the cervical third of the palatal surface, while less effective for movement, generates the least stress.

Introduction: Temporary anchorage devices (TADs) represent an essential instrument under difficult anchorage conditions, especially when the procedure is approached with an aligner technique. The objective of this paper is to describe a possible sequence of orthodontic treatment of impacted canines with aligners supported by orthodontic mini-screws. Materials and Methods: The resolution of impacted canines requires a specific clinical sequence constituted by different steps: the space creation, the surgical exposure, and the orthodontic traction (on the horizontal, vertical, and buccal direction). Following this sequence, two different clinical scenarios can be identified following the space available and the initial malocclusion. The first scenario is constituted by recreating the space for the impacted canine along with the correction of the malocclusion by means of an aligner system and then approaching the de-impaction with TADs. The second clinical scenario is related to the canine-first approach, an immediate de-impaction stage based solely on the use of TADs and sectional wires, and then a finishing phase with aligners. Results: Both approaches to the treatment of impacted canines can be considered reliable, but of course selecting one or the other depends on the space available in the upper arch and on the initial malocclusion. Conclusions: The use of aligners in the treatment of impacted canines in combination with TADs and sectional wires represents a viable alternative option to the conventional systems for canine disinclusion. When the treatment is managed with the presented approaches, no further cooperation with the patient is required in order to support the forced eruption, and an ideal biomechanical approach can be easily applied with one or two mini-screws.

Background and Objectives: The key factor that enables osteoblastic activity and the formation of new bone, as well as gingiva, during orthodontic tooth extrusion (OE) is the periodontal ligament. The reaction of periodontal tissues associated with changes in the gingiva is a part of orthodontic tooth displacement. The aim of this study was to examine the effect of OE on the width of the zone of the keratinized and attached gingiva, the position of the mucogingival junction, and the height of the interdental papillae in the region where the OE was performed as well as in the adjacent region. Materials and Methods: This research included 28 adult patients (both orthodontically treated and untreated). The treated group included 15 patients, in whom orthodontic extrusion of the upper or lower frontal teeth was indicated and performed. The untreated group included 13 patients, with no previous or undergoing orthodontic treatment. Patients with periodontal disease and periodontal pockets in the frontal region and patients allergic to iodine were excluded from the study. Gingivomorphometric measurements were performed on two occasions in three groups of teeth (24 extruded and 30 agonist teeth in the treated patients; 66 teeth in the untreated patients). Statistical analysis of the obtained data was performed using the software package SPSS version 26.0. Results: Orthodontic extrusion induced changes in the position of the mucogingival line and an increase in the width of the keratinized gingiva. There were no statistically significant effects on the depth of the gingival sulcus, the attached gingiva width, or the height of the interdental papillae. Conclusions: Orthodontic tooth extrusion has an effect on the periodontium in the observed region. Vertical orthodontic force, directed towards the coronal plane, affects the surrounding soft oral tissues.

Background This 20-year retrospective study aimed to evaluate the treatment methods used in patients with impacted maxillary permanent canines and to determine the occurrence of ankylotic and resorptive processes and their association with potential risk factors. Methods The cohort consisted of 351 consecutive Caucasian patients (120 males and 231 females, mean age 18.4 and 19.9 years, respectively) with 420 impacted maxillary permanent canines. CT and CBCT findings were subsequently confirmed during surgery. Statistical analyses were performed by the generalized linear models, Pearson x 2 and Fisher exact tests using the statistical programs R and Statistica v. 14. Results A total of 273 (65.0%) impacted canines were aligned in the dental arch by orthodontic traction after surgical exposure, this treatment was predominant in patients under 20 years of age. Surgical extraction was performed in 115 (27.2%) impacted canines and was more common in older patients. Ankylotic changes were recorded in 61 (14.5%) impacted canines. The probability of ankylosis increased with age, particularly after the patient’s 20th year of life ( p  < 0.001). Patients were 1.2% likely to develop ankylosis at age 15 years, 4.3% at age 20 years, 14.1% at age 25 years, and 96.8% at age 45 years. Invasive cervical root resorption (ICRR) was found in 8 (1.9%) canines. In 4 canines (1.0%), root ankylosis in addition to ICRR was observed. In contrast to ankylosis, whose frequency of occurrence increased with age, the occurrence of ICRR resulting from PDL damage during surgery was more typical in younger patients. Canines in a high position above the root apices of the adjacent teeth, with a horizontal inclination of the longitudinal axis, with the crown located deep in the center of the alveolar bone and with labiopalatal position, should be considered critically impacted canines with a high risk to failure of orthodontic traction. Conclusion In conclusion, the treatment of impacted canines depends mainly on the age of the patient, and the position and inclination of the longitudinal axis of the impacted tooth. To select an adequate treatment method, we recommend CBCT examination, which allows a precise analysis of the position of impacted canines.

Background To identify which factors influence the traction time of impacted maxillary canines using a combined orthodontic-surgical approach and to create a multivariate model to predict canine traction time. Methods Patients undergoing traction of impacted maxillary canines by a single orthodontist were selected. Seventy patients (mean age ± SD): 19.32 ± 8.81) meeting the inclusion criteria were enrolled in the study. They had 89 impacted canines (69 palatally displaced and 20 in a buccal position). Variables that could be related to orthodontic treatment as a whole and to impaction and its treatment were recorded for each patient. The treatment predictors were explored by univariate Cox regression and multivariate generalized linear mixed models (GLMM). A multivariate analysis was performed using a mixed-effects parametric survival analysis (MMPSA) Weibull model to assess the contribution of each of the predictive variables and to create a multiple linear regression model to explain canine traction time. Results Cox regression showed significant association between traction time and age ( p  = 0.013) and the number of failed appointments ( p  < 0.001). An MMPSA Weibull model to build a predictive model based on the Akaike information criterion (AIC) showed that interceptive maxillary expansion significantly reduced traction time ( p  = 0.002). In contrast, traction time increased with a wider angle of the impacted canine relative to the midline, with missed appointments, and with radiological overlap with lateral or central incisors. Conclusions The orthodontic treatment time to align impacted maxillary canines increases with radiological overlap with lateral and central incisors, a wider angle to the midline, the absence of interceptive maxillary expansion, and missed appointments.

Background Primary failure of eruption (PFE) is a rare disease defined as incomplete tooth eruption despite the presence of a clear eruption pathway. Orthodontic extrusion is not feasible in this case because it results in ankylosis of teeth. To the best of our knowledge, besides the study of Ahmad et al. (Eur J Orthod 28:535-540, 2006), no study has systematically analysed the clinical features of and factors associated with PFE. Therefore, the aim of this study was to systematically evaluate the current literature (from 2006 to 2017) for new insights and developments on the aetiology, diagnosis, genetics, and treatment options of PFE. Methods Following the PRISMA guidelines, a systematic search was performed using the PubMed/Medline database for studies reporting on PFE. The following terms were used: “primary failure of tooth eruption”, “primary failure of eruption”, “tooth eruption failure”, and “PFE”. Results Overall, 17 articles reporting clinical data of 314 patients were identified. In all patients, the molars were affected. In 81 reported cases, both the molars and the premolars were affected by PFE. Further, 38 patients’ primary teeth were also affected. In 27 patients, no family members were affected. Additional dental anomalies were observed in 39 patients. A total of 51 different variants of the PTH1R gene associated with PFE were recorded. Conclusions Infraocclusion of the posterior teeth, especially if both sides are affected, is the hallmark of PFE. If a patient is affected by PFE, all teeth distal to the most mesial tooth are also affected by PFE. Primary teeth can also be impacted; however, this may not necessarily occur. If a patient is suspected of having PFE, a genetic test for mutation in the PTH1R gene should be recommended prior to any orthodontic treatment to avoid ankylosis. Treatment options depend on the patient’s age and the clinical situation, and they must be evaluated individually.

Purpose The present study aims to systematically review the literature on the effect of combined surgical-orthodontic treatment on the periodontal health of labially maxillary impacted canines, comparing the results between the three available surgical approaches, open and closed eruption technique and apically positioned flap. Methods Seven electronic databases and three registers were searched until September 2024 and lists of references from relevant publications were screened to identify studies (randomised (RCTs) / controlled clinical trials (CCTs) and observational) assessing the periodontal status of labially maxillary impacted canines after combined surgical-orthodontic treatment. Participants consisted of medically and periodontally healthy individuals with labially impacted canines and their untreated contralaterals as comparison. The outcomes assessed were plaque accumulation, gingival inflammation, gingival recession, probing pocket depth, keratinised gingiva width, attached gingiva width, and crestal bone loss. The risk of bias was evaluated using the ROBINS-I tool for the CCTs and Newcastle-Otawa tool for the observational studies. Results A total of 1829 studies were identified, and seven were included in the review (one CCT and six observational studies). All evaluated soft tissue periodontal parameters had the most negative outcomes after excisional uncovering, however these findings did not reach clinical significance. When closed eruption technique or an apically positioned flap was performed, the periodontal outcomes were similar to those of untreated teeth. Conclusions This review found no clinically significant adverse effects on the periodontium after combined surgical-orthodontic treatment of labially impacted maxillary canines. Further high-quality, low-bias clinical trials are needed to assess post-treatment periodontal status.

ABSTRACT Introduction: The relationship between orthodontic disimpaction of unilaterally impacted maxillary canines (MCs) and volumetric changes in the maxillary sinus (MS) remains underexplored. Objective: This study aimed to evaluate MS volume alterations following orthodontic traction of impacted MCs, using cone-beam computed tomography (CBCT). Additionally, it examined differences based on the impaction site (buccal vs. palatal) and sex. Material and Methods: A prospective split-mouth study was conducted on patients with unilaterally impacted MCs. CBCT scans were taken before and after orthodontic disimpaction. MS volume was measured using three-dimensional reconstruction software. Comparisons were made between the impacted and non-impacted sides, buccal and palatal impactions, and male and female patients. Statistical analysis included paired t-tests and analysis of variance (ANOVA) for group comparisons. A multifactorial regression analysis was performed to identify predictor variables influencing MS volume normalization. Results: A significant increase in MS volume was observed on the previously impacted side, following orthodontic disimpaction (p < 0.05). Buccally impacted MCs showed greater pretreatment sinus volume, compared to palatally impacted MCs. Additionally, statistically significant sex-based differences were not noted, in the relative volumetric change between sexes (p > 0.05). It was indicated by our study that younger age, palatally impacted MCs, shorter treatment duration, increased distance of the root tip of impacted MC from MS floor, and pretreatment MS volume differences were significant predictors of MS volume normalization. Conclusion: Orthodontic disimpaction of unilaterally impacted MCs influenced MS volume, with greater mean change of MS volume in palatal impactions. RESUMO Introdução: A relação entre a desimpacção ortodôntica de caninos superiores (CSs) impactados unilateralmente e as alterações volumétricas no seio maxilar (SM) permanece pouco explorada. Objetivo: Este estudo teve como objetivo avaliar as alterações volumétricas do SM após a tração ortodôntica de CSs impactados, utilizando tomografia computadorizada de feixe cônico (TCFC). Adicionalmente, examinou as diferenças com base no local da impacção (vestibular vs. palatina) e no sexo. Material e Métodos: Foi realizado um estudo prospectivo de boca dividida em pacientes com CSs impactados unilateralmente. As TCFCs foram obtidas antes e depois da desimpacção ortodôntica. O volume do SM foi mensurado utilizando um software de reconstrução tridimensional. Foram feitas comparações entre os lados impactado e não impactado, entre impacções vestibulares e palatinas, e entre pacientes dos sexos masculino e feminino. A análise estatística incluiu testes t pareados e análise de variância (ANOVA) para comparações entre os grupos. Uma análise de regressão multifatorial foi realizada para identificar variáveis preditoras que influenciam a normalização do volume do SM. Resultados: Observou-se um aumento significativo no volume do SM no lado previamente impactado, após a desimpacção ortodôntica (p < 0,05). Os CSs impactados por vestibular apresentaram maior volume do SM antes do tratamento, em comparação com os CSs impactados por palatina. Além disso, não foram observadas diferenças estatisticamente significativas entre os sexos na variação volumétrica relativa (p > 0,05). O presente estudo indicou que idade mais jovem, CSs impactados por palatina, menor duração do tratamento, maior distância da ponta da raiz do CS impactado em relação ao assoalho do SM e diferenças no volume do SM antes do tratamento foram preditores significativos da normalização do volume do SM. Conclusão: A desimpacção ortodôntica de CSs impactados unilateralmente influenciou o volume do SM, com maior variação média do volume do SM em impacções palatinas.

Background The effects of traction forces at different angles on impacted central incisors(ICI)with varying inverted angles (IA) may be different. The objective of this study was to analyze the biomechanical effects of different force directions (FD) on developmentally inverted ICI with multi-angle variations and to offer insights and guidance for the treatment of inverted ICI. Methods Three-dimensional finite element method was employed to simulate clinical scenarios of inverted ICI traction. As such, 0.2 N of force (direction: antero-superior angles of 90°, 100°, 110°, 120°, and 130° relative to the long axis of the inverted ICI crown) was applied to the inverted ICI with inverse angles (IA) of 40°, 30°, 20°, 10° and 0°. Inverted ICI apical displacement and Von Mises stress on periodontal ligament (PDL) and alveolar bone were compared. Results IA and FD showed minimal influence on the stress distribution in the PDL, as higher stresses were concentrated in the apical region. The higher stresses in the alveolar bone are focused on the cervical and apical regions of the tooth. In particular, IA exerts a more significant impact on stress distribution in the alveolar bone than FD. The influence of IA on the apical displacement of inverted ICI is larger than that of FD. Conclusions To promote the health of the root and periodontal tissues, it is recommended to use an angle of 100°-110° relative to the long axis of the ICI crown when dealing with a large IA (> 20°) developmentally inverted ICI. Conversely, an angle of 110°-120° can be used.