Root resorption associated with orthodontic tooth movement: A systematic review

HDAC9-Mediated Pyroptosis Promotes Orthodontically Induced Inflammatory Root Resorption

INTRODUCTION AND AIMS

Orthodontically induced inflammatory root resorption (OIIRR) is a common iatrogenic outcome of orthodontic treatment. Both epigenetic modifications and pyroptosis have demonstrated a certain role in OIIRR. This study aims to investigate whether epigenetic modifications regulate pyroptosis to be involved in OIIRR.

METHOD

Rat model of OIIRR was established, and the periodontal tissues were utilized for H&E staining, TRAP staining, immunofluorescence, transcriptome sequencing, and RT-qPCR analysis. Human periodontal ligament fibroblasts (hPDLFs) were overexpressed with HDAC9, treated with pyroptosis inhibitor, incubated with osteoclast, and then subjected to CUT&Tag sequencing.

RESULTS

Orthodontic force increased the distance of orthodontic tooth movement and the abundance of osteoclast. Transcriptome sequencing identified that Hdac9 was upregulated in the periodontal tissues of OIIRR rats compared to the control. Immunofluorescence revealed that HDAC9 was present in periodontal ligament fibroblasts, with reduced fluorescence of HDAC9 in OIIRR compared to the control. HDAC9 overexpression in hPDLFs induced pyroptosis and promoted osteoclast differentiation. These effects were reversed by pyroptosis inhibitor. CUT&Tag analysis showed that HDAC9 overexpression resulted in an enrichment of deacetylated genes on mitochondrial dysfunction-associated pathways. CUT&Tag-PCR analysis confirmed reduced H3K9ac enrichment on the mitochondrial dysfunction-associated genes VPS13D, AQP1, PEX2, CDK1, and PLEKHA1 after HDAC9 overexpression, and RT-qPCR analysis revealed a corresponding decrease in their respective expression levels. Accordingly, the ROS level was also increased by HDAC9 overexpression.

CONCLUSION

HDAC9-mediated histone deacetylation induces mitochondrial dysfunction and pyroptosis in hPDLFs, thereby promoting osteoclast differentiation and OIIRR progression.

CLINICAL RELEVANCE

This study reveals the regulatory mechanism of pyroptosis in OIIRR from the perspective of epigenetic modifications, providing new insights into the pathogenesis of OIIRR.

AI-AIDED VOLUMETRIC ROOT RESORPTION ASSESSMENT FOLLOWING PERSONALIZED FORCES IN ORTHODONTICS: PRELIMINARY RESULTS OF A RANDOMIZED CLINICAL TRIAL

INTRODUCTION

External apical root resorption (EARR) is an undesirable loss of hard tissues of the tooth root frequently affecting to the maxillary incisors. The magnitude of orthodontic forces is a major treatment-related factor associated with EARR occurrence in orthodontics. The primary aim of the present randomized clinical trial was (i) to quantify the impact of a sequence of personalized force archwires on EARR compared to the conventional standard of care and (ii) compare the 3D-quantification of EARR using two quantification methods (manual or automated AI-aided segmentation).

MATERIAL AND METHODS

A superiority two arms-parallel-randomized clinical trial (RCT) was conducted to quantify the EARR of two regime forces [CONSORT-guidelines]. A total of 18/43 patients were randomly assigned [block-size: 4] to Control Group [Ni-Ti archwires sequence] or Experimental Group [selective individualized force archwires]. After 142 days sectorial CBCT were obtained; upper incisors were segmented manually and with AI and the volume/length of root quantified. Method error/descriptive statistics (mean; SD; range) and Student t-test were used to assess the differences between groups (Post hoc adjustment for confounders [95% CI; P < .05]).

RESULTS

The total root volume loss detected by AI was 2.44 ± 6.59 mm3 / 2.42 ± 4.75 mm3 (P > .05) and the mean root length loss was 0.20± 0.23mm/0.42 ± 0.43 mm (P = .045) for control/test group, respectively. Despite length loss showed similar changes when it was quantified with both methods, manual and automatic segmentations (P > .05), differences are observed at volume loss. The results demonstrated greater volume loss detection with manual segmentation than with AI-aided segmentation at the global level, volume by thirds, and 4 mm from the apex. However, as we approached apically, the differences equalized and even diminished, resulting in a greater loss with automatic segmentation 1 mm from the apex in the EG (P = .011).

CONCLUSIONS

A non direct-force-dependent effect over EARR (6 months) was observed. Individualized force induces slightly higher root resorption at the apical third at 1-2 mm.

Evaluation of External Apical Root Resorption and the Relevance of Intermediate Radiography in Non-Extraction Treatment With Fixed Appliances for Adolescents With Crowding: A Multicenter Randomised Controlled Trial Using CBCT

OBJECTIVES

The objectives are to assess the severity and frequency of clinically relevant external apical root resorption (EARR) ≥ 2 mm during orthodontic treatment with Damon passive self-ligating and Victory conventional standardised fixed appliance systems and to evaluate the relevance of intermediate radiographic examinations for early detection and prevention of severe EARR.

MATERIALS AND METHODS

Adolescents aged 12-17 years with crowded and displaced teeth planned for non-extraction treatment were recruited from three orthodontic clinics. Participants were randomly allocated in a 1:1 ratio to treatment with either Damon Q (n = 35) or Victory (n = 40) using stratified blocks, with allocation concealed. EARR was assessed for all roots from incisors to molars using multiplanar reconstruction in cone beam computed tomography (CBCT) images acquired from various CBCT machines before, during and after treatment.

RESULTS

Sixty-two patients were included in the EARR analysis. The upper incisors were the most affected tooth group, with mean EARR values of 0.20 mm for Damon and 0.51 mm for Victory (NS, alpha 1%). The frequency of clinically relevant EARR in this tooth group was 5.0% for Damon and 7.2% for Victory (NS, alpha 5%). Only one case with clinically relevant EARR after treatment was identified in the intermediate radiographic examinations.

CONCLUSIONS

The overall severity and frequency of EARR were below clinically relevant levels in both treatment groups. The results strengthen the evidence that routine intermediate radiography appears to be of limited relevance for early detection and prevention of severe EARR in non-extraction treatments for adolescents with crowded teeth.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT05664282.

Effects of different corticotomy approaches on anterior retraction with clear aligners: a finite element study

BACKGROUND

Corticotomy has been shown to influence the biomechanical behavior of dentoalveolar structures during anterior retraction. However, most research on corticotomy in orthodontics focused on fixed appliance models. This study aimed to investigate the biomechanical effects of different corticotomy approaches that facilitate anterior retraction with clear aligners.

METHODS

Based on research criteria, one volunteer was selected(24 years old, male) and cone beam computed tomography (CBCT) data were obtained. Finite element models were constructed using reverse engineering, including maxillary dentition without first premolars, maxilla, periodontal ligaments (PDLs), attachments, and aligners. Four models with varying corticotomy approaches were developed: Model 1 (no corticotomy), Model 2 (corticotomy with bilateral horizontal and vertical incisions), Model 3 (corticotomy with unilateral buccal horizontal and vertical incisions), and Model 4 (corticotomy with unilateral buccal vertical incisions). Stress distribution in the PDLs and alveolar bone, as well as initial anterior tooth displacement, were computerized and evaluated using three-dimensional finite element analysis.

RESULTS

Stress distribution in the PDLs was similar across all models, with tensile stress concentrated at labial region of the coronal third of the root and lingual apical region and compressive stress at lingual region of the coronal third of the root and labial apical region. Differences were observed in stress distribution within the alveolar bone across all models. After corticotomy, stress concentration in the alveolar bone decreased in the incision regions but increased around the extraction space. Anterior teeth demonstrated lingual and distal inclination across all models. Models with horizontal and vertical incisions (Models 2 and 3) exhibited more significant crown displacement and more pronounced inclination compared to Model 1. The effects were more prominent in bilateral incisions compared to unilateral ones.

CONCLUSIONS

Corticotomy affected the mechanical response of alveolar bone during anterior retraction, promoting bone remodeling and tooth movement. Incisions near the apical region or aligned with the direction of tooth movement may better facilitate anterior retraction. During anterior retraction with clear aligners, anterior teeth exhibited tipping movement, and corticotomy modified this movement pattern. Horizontal and vertical incisions may exacerbate the inclination of anterior teeth. The changes in tooth movement patterns after corticotomy should be carefully considered in orthodontic treatment planning.

Effect of multiple hook heights and positions during en masse maxillary distalization using infrazygomatic crest miniscrew- single and double points of force application: a finite element analysis study

BACKGROUND

This study aimed to simulate maxillary dentition distalization as one unit anchored to infrazygomatic crest (IZC) miniscrew using different hook positions and lengths.

MATERIALS AND METHODS

Eleven finite-element models (FEM) were constructed from a cone beam computed tomography scan of a patient with Class II malocclusion. Different force vectors to the IZC miniscrew were simulated using one point of force application either mesial to the canine or mesial to the first premolar, using different hook lengths (0, 2, 4, and 6 mm). In the novel approach, two point-force system was constructed using double-hook retraction in three conditions. The FEM yielded tooth displacement patterns and stress contour plots of the periodontal ligament.

RESULTS

When hooks were placed mesial to the canine, the incisor showed palatal translation with controlled palatal tipping at 0 and 2 mm, palatal bodily displacement at 4 mm, and palatal translation with torquing at 6 mm. In hooks mesial to the first premolar, the pattern showed palatal translation with torquing, except with the 0-mm hook where controlled palatal tipping occurred. Whereas, vertically, it shows extrusion at the 0- and 2-mm hooks mesial to the first premolar and intrusion with the remaining single hook simulations. The molar exhibited translation with controlled distal tipping at all hook lengths mesial to the canine and 0 mm mesial to the first premolar, while it demonstrated distal translation with torquing at 2-,4-, and 6-mm hooks mesial to the first premolar. Vertically, it showed extrusion with hooks mesial to the canine, which changed to intrusion with hooks mesial to the first premolar. In double-hook simulations, the incisor showed bodily displacement only with hooks mesial to the canine and second premolar, whereas the molar showed distal bodily movement with hooks mesial to the first and second premolars.

CONCLUSION

Hook height and position variations are crucial in the resultant displacement pattern. Accordingly, different force systems should be tailored individually based on the patient's initial malocclusion.

Artesunate Promotes Bone Remodeling Through TRAF6-Mediated NF-κB Signaling Under Orthodontic Stress in Diabetic Rats

OBJECTIVES

To determine the effects of artesunate (ART) on bone remodeling in vivo under orthodontic stress in diabetic rats and explore the underlying mechanisms in vitro.

MATERIALS AND METHODS

A rat model of type 2 diabetes mellitus with orthodontic tooth movement was established. The rats received ART and/or metformin (Met) orally. The effects of ART and Met on periodontium changes were evaluated using tartrate-resistant acid phosphatase and immunohistochemical staining. Molecular docking analyses were employed to investigate the mechanisms of ART action. In vitro, the effects of ART on osteogenic and osteoclastic activity were explored by examining TRAF6 and NF-κB expression under hyperglycemic and static pressure conditions via immunofluorescence and Western blotting.

RESULTS

ART enhanced bone metabolism despite hyperglycemia, though mechanical stress still induced bone resorption. Treatment with ART alone or in combination with Met promoted osteogenesis. TRAF6, NF-κB and the OPG/RANKL/RANK signaling pathways have been identified as key mediators of these effects. The expression of the osteogenesis-associated factor OPG increased after ART and Met treatment, while that of TRAF6 and the osteoclast-associated factors RANKL and NF-κB decreased.

CONCLUSIONS

Increased bone resorption and decreased bone formation are characteristics of type 2 diabetes, impacting orthodontic tooth movement. ART administration alone promotes bone remodeling under static pressure and hyperglycemic conditions. These effects are mediated by lowering blood sugar levels, inhibiting osteoclast function, and improving osteogenesis through mechanisms closely associated with the OPG/TRAF6/NF-κB signaling pathway.

Quantitative analysis and clinical determinants of orthodontically induced root resorption using automated tooth segmentation from CBCT imaging

BACKGROUND

Orthodontically induced root resorption (OIRR) is difficult to assess accurately using traditional 2D imaging due to distortion and low sensitivity. While CBCT offers more precise 3D evaluation, manual segmentation remains labor-intensive and prone to variability. Recent advances in deep learning enable automatic, accurate tooth segmentation from CBCT images. This study applies deep learning and CBCT technology to quantify OIRR and analyze its risk factors, aiming to improve assessment accuracy, efficiency, and clinical decision-making.

METHOD

This study retrospectively analyzed CBCT scans of 108 orthodontic patients to assess OIRR using deep learning-based tooth segmentation and volumetric analysis. Statistical analysis was performed using linear regression to evaluate the influence of patient-related factors. A significance level of p < 0.05 was considered statistically significant.

RESULTS

Root volume significantly decreased after orthodontic treatment (p < 0.001). Age, gender, open (deep) bite, severe crowding, and other factors significantly influenced root resorption rates in different tooth positions. Multivariable regression analysis showed these factors can predict root resorption, explaining 3% to 15.4% of the variance.

CONCLUSION

This study applied a deep learning model to accurately assess root volume changes using CBCT, revealing significant root volume reduction after orthodontic treatment. It found that underage patients experienced less root resorption, while factors like anterior open bite and deep overbite influenced resorption in specific teeth, though skeletal pattern, overjet, and underbite were not significant predictors.

Importance of the early phase of orthodontic force application in the induction of root resorption

OBJECTIVE

To investigate the effectiveness of early and short-term administration of lithium (Li) during orthodontic force application (OFA) in preventing orthodontically induced root resorption (OIRR) and verify the importance of the early phase of OFA in the induction of OIRR.

MATERIALS AND METHODS

Bilateral maxillary first molars of 10-week-old male Wistar rats were moved for 14 days using a closed coil spring inserted between the first molar and the incisor. The rats were randomly grouped into three groups: a group receiving Li for the first 4 days, a group receiving Li daily for 14 days, and a control group receiving a vehicle (saline). Orthodontic tooth movement (OTM) was measured using microcomputed tomography on day 14. The OIRR, osteoclasts, and odontoclasts were evaluated via histological analysis. Immunohistochemical staining for the receptor-activated NF-kB ligand and osteoprotegerin was also performed.

RESULTS

The OTM distance did not differ among the three groups, and the pattern of OTM changed from tipping to bodily movement for both Li groups. Early and short-term administration of Li suppressed OIRR on day 14 as effectively as long-term administration for 14 days. The observed odontoclasts on days 4 and 14 were significantly reduced in both Li groups. Osteoprotegerin expression was significantly increased on day 14 in both groups receiving Li relative to the vehicle group.

CONCLUSIONS

Early and short-term Li administration effectively suppressed OIRR. This suggests that the early phase of OFA plays an important role in the induction of OIRR.

How Does Allergen Sensitization Affect Orthodontic Tooth Movement-Associated Phenomena? A Systematic Review of Animal Studies

Background: The immune reactions of patients suffering from chronic allergies and asthma are associated with systemic imbalances that may lead to the overexpression of mediators potentially involved in bone remodeling during orthodontic tooth movement. Aim: The aim of this systematic review was to evaluate the existing evidence from animal studies with regard to the effects of allergen sensitization on the phenomena correlated with orthodontically induced tooth movement. Materials and Methods: This systematic review was based on PRISMA 2020 guidelines. A search without restrictions and hand searching were performed from inception to December 2024. The investigation focused on the impact of allergen sensitization on phenomena associated with orthodontic tooth movement. After the retrieval and selection of relevant studies, data extraction was performed, and the data's risk of bias was evaluated with the SYRCLE's Risk of Bias Tool. Results: From the detected records, the inclusion criteria were met by only three studies. At the beginning of tooth movement, periodontal ligament was found to be more compressed in the stress area and more stretched in the tension area in sensitized animals. The amount of tooth movement after 14 days of force application was also greater. However, there were conflicting outcomes regarding root resorption. The risk of bias in the retrieved studies was assessed as high overall. Conclusions: Despite the fact that existing evidence is not directly related to human beings and is based on a limited number of animal studies, allergen sensitization could potentially influence the phenomena associated with orthodontic tooth movement, and orthodontists should be aware of the relevant implications.

Piezo1 promotes double-directional differentiation from human periodontal ligament progenitor cells

OBJECTIVES

Human periodontal ligament (PDL) progenitor cells (hPDLPCs) sense mechanical stress and differentiate into osteoblasts, cementoblasts, and fibroblasts during orthodontic tooth movement. The mechanosensitive ion channel Piezo1 has been known to be present in PDL tissues and is involved in mineralization during bone regeneration. However, the functional role and underlying mechanisms of Piezo1 in osteogenesis and cementogenesis are unknown. We hypothesize that Piezo proteins are expressed in and regulate the differentiation of hPDLPCs.

METHODS

We examined the effects of Piezo1 activation, by agonist and mechanical stretching, on the expression of osteogenesis- and cementogenesis-related molecules in hPDLPCs using RT-PCR, western blotting, and immunofluorescence methods.

RESULTS

hPDLPCs showed calcium influx in Piezo1 and Piezo2, but not in TRPV4 and its channels. In hPDLPCs, the Piezo1 agonist Yoda1 significantly upregulated osteogenesis- and cementogenesis-related molecules through the Ca2+/CREB pathway. To investigate the role of Piezo1 in hPDLPC-mediated differentiation, knockout (KO) of Piezo1 in hPDLPCs was generated; significant downregulation of osteogenesis- and cementogenesis-related molecules was observed in KO hPDLPCs. Furthermore, Piezo1 enhanced the mineralization of hPDLPCs.

CONCLUSIONS

hPDLPCs expressed Piezo1 and Piezo2. Yoda1, Piezo1 agonist, significantly upregulated osteogenesis- and cementogenesis-related molecules through the Ca2+/CREB signaling pathway.

IL6-Dependent PIEZO1 Activation Promotes M1-Mediated Orthodontic Root Resorption via CXCL12/CXCR4

Orthodontic root resorption (ORR) is a common yet significant complication of orthodontic treatment, largely driven by interactions between periodontal ligament cells (PDLCs) and M1 macrophages. Despite the clinical relevance of ORR, the role of mechanosensitive ion channels in PDLC-mediated ORR and the underlying mechanisms regulating inflammatory cell recruitment remain poorly understood. Here, we identified PIEZO1 as a critical mechanosensitive ion channel that modulates monocyte recruitment and ORR. Using in vivo models treated with the PIEZO1 activator Yoda1 and inhibitor AAV-shPiezo1, we demonstrated that PIEZO1 activation promoted the recruitment of Ly6Chi inflammatory monocytes and exacerbated ORR. In contrast, PIEZO1 inhibition attenuated ORR and the accumulation of M1 macrophages. Mechanistically, PIEZO1 positively regulated the C-X-C motif chemokine 12 (CXCL12) and its receptor, C-X-C chemokine receptor type 4 (CXCR4). Blocking the CXCL12/CXCR4 axis using the CXCR4 antagonist AMD3100 significantly alleviated ORR, reversed M1 macrophage accumulation, and mitigated the recruitment of CD11b+Ly6Chi monocytes. Transwell migration assays with application of the PIEZO1 activator Yoda1 and PIEZO1 inhibitor GsMTX4 consistently confirmed the PIEZO1/CXCL12/CXCR4 axis as a key driver of PDLC-monocyte interactions. Notably, PIEZO1 overactivation was linked to excessive IL-6 production, and IL-6 deficiency inhibited the activation of PIEZO1 induced by Yoda1, leading to attenuation of ORR, M1 macrophage accumulation, and CXCL12/CXCR4 axis activation. Collectively, these findings reveal PIEZO1 in PDLCs as a pivotal modulator of inflammatory monocyte recruitment via the CXCL12/CXCR4 axis in ORR, with IL-6 playing an essential role in PIEZO1 activation. This study provides new insights into the molecular crosstalk between PDLCs and macrophages, offering potential therapeutic targets for mitigating ORR in orthodontic patients.

Does the Phase-One Functional Therapy Increase the Risk of an External Apical Root Resorption Following the Phase-Two Fixed Orthodontic Treatment? A Pilot Study

Background: This retrospective study aimed to analyze the frequency and extent of apical root resorptions (EARR) during orthodontic treatment in the upper and lower incisors, as well as lower molars, using orthopantomograms (OPG). Potential influencing factors such as age, gender, root shape, type of orthodontic appliance, and treatment duration were examined as well. Methods: A total of 57 patients who completed their treatment at the orthodontic department of the Goethe University of Frankfurt between 2011 and 2018 were included in the study. These patients had a combined total of 570 teeth, which were divided into two groups. Group 1 consisted of 20 patients (average age at T0: 10.1 ± 1.2 years old) received a one-phase fixed orthodontic treatment using passive self-ligating Damon bracket system (average duration of 2.1 years ± 6 months), while group 2 consisted of 37 patients (average age at T0: 12.4 ± 2.8 years old) underwent a two-phase therapy, which involved a phase-one functional therapy (average duration of 1.7 years ± 6 months) prior to the phase-two fixed orthodontic treatment with the Damon system (average duration of 1.5 ± 4 months) with a total treatment time of 3.2 years ± 7 months. To determine the extent of post-treatment root resorption of the upper and lower incisors, as well as the first lower molars, crown-root ratio was calculated for each tooth using the pre- and post-treatment OPGs. Additionally, each tooth was assigned a degree of resorption according to the Levander and Malmgren classification. The inter-group comparisons were conducted using the Wilcoxon Mann-Whitney U test. Spearman's correlation analysis was used to assess the relationship between age, treatment duration, and EARR. The association between gender, root morphology, and EARR was evaluated using the Wilcoxon Mann-Whitney U test. For nominally scaled variables, the Chi-square test was used. The statistical significance was set at p < 0.05. Results: No statistically significant differences were seen between groups 1 and 2 regarding the degree of root resorption (p = 0.89). The study found that the average root resorption for all examined teeth was -5.14%, indicating a slight reduction in the length of the tooth roots after orthodontic treatment. However, no significant differences were observed concerning gender, age, type of orthodontic appliance or treatment duration. Comparisons between upper and lower jaws also did not yield statistically significant differences. The majority of teeth in the study exhibited a normal root shape. The short root length and a pipette formed roots were significantly associated with a higher risk of root resorption (p = 0.001). Conclusions: The study's findings suggest that the two-phase orthodontic treatment does not increase the risk of EARR compared to one-phase therapy significantly. Some degree of root resorption occurred as a result of orthodontic treatment in both groups. Notably, abnormal root forms were identified as influential factors that could help predict the likelihood of root resorption following orthodontic treatment.

Automatic 3-dimensional quantification of orthodontically induced root resorption in cone-beam computed tomography images based on deep learning

INTRODUCTION

Orthodontically induced root resorption (OIRR) is a common and undesirable consequence of orthodontic treatment. Traditionally, studies employ manual methods to conduct 3-dimensional quantitative analysis of OIRR via cone-beam computed tomography (CBCT), which is often subjective and time-consuming. With advancements in computer technology, deep learning-based approaches have gained traction in medical image processing. This study presents a deep learning-based model for the fully automatic extraction of root volume information and the localization of root resorption from CBCT images.

METHODS

In this cross-sectional, retrospective study, 4534 teeth from 105 patients were used to train and validate an automatic model for OIRR quantification. The protocol encompassed several steps: preprocessing of CBCT images involving automatic tooth segmentation and conversion into point clouds, followed by segmentation of tooth crowns and roots via the Dynamic Graph Convolutional Neural Network. The root volume was subsequently calculated, and OIRR localization was performed. The intraclass correlation coefficient was employed to validate the consistency between the automatic model and manual measurements.

RESULTS

The proposed method strongly correlated with manual measurements in terms of root volume and OIRR severity assessment. The intraclass correlation coefficient values for average volume measurements at each tooth position exceeded 0.95 (P <0.001), with the accuracy of different OIRR severity classifications surpassing 0.8.

CONCLUSIONS

The proposed methodology provides automatic and reliable tools for OIRR assessment, offering potential improvements in orthodontic treatment planning and monitoring.

Three-dimensional assessment of alveolar bone changes and root resorption in extraction patients after fixed orthodontic treatment: A prospective study

BACKGROUND

The aim of this study was to evaluate the alveolar crestal bone height, alveolar bone thickness, and root resorption in mandibular incisors after fixed orthodontic treatment.

METHODS

A total of 35 patients (mean age 17.02 ± 3.24 years) with moderate to severe mandibular anterior crowding requiring first premolar extraction were included. Cone beam computed tomography scans of the mandibular anterior region were obtained from the patients before and after orthodontic treatment. The alveolar crestal bone height, cortical bone thickness (CBT) (at apex and midroot level), labial and lingual alveolar bone thickness, and root resorption were assessed for all mandibular incisors. Paired Student's t test was used to compare pretreatment and post-treatment alveolar bone changes and root resorption.

RESULTS

A significant decrease in lingual crestal bone height was observed in all mandibular incisors after orthodontic treatment (P < 0.001). Lingual CBT decreased at the midroot level significantly for all mandibular incisors after completion of orthodontic treatment (P < 0.001). A significant decrease in total lingual bone thickness was observed in all mandibular incisors (P < 0.001). Root lengths of mandibular incisors decreased significantly in the sagittal and coronal sections after orthodontic treatment (P < 0.001).

CONCLUSIONS

Fixed orthodontic treatment with premolar extraction results in a significant reduction of alveolar crestal bone height, CBT (at midroot level), and alveolar bone thickness on the lingual aspect of mandibular incisors. Significant orthodontically induced inflammatory root resorption was observed in all mandibular incisors after orthodontic treatment.

Effect of low-intensity pulsed ultrasound on the mineralization of force-treated cementoblasts and orthodontically induced inflammatory root resorption via the Lamin A/C-Yes associated protein axis

AIMS

Orthodontic treatment commonly results in orthodontically induced inflammatory root resorption (OIIRR). This condition arises from excessive orthodontic force, which triggerslocal inflammatory responses and impedes cementoblasts' mineralization capacity. Low-intensity pulsed ultrasound (LIPUS) shows potential in reducing OIIRR. However, the precise mechanisms through which LIPUS reduces OIIRR remain unclear. This study aimed to explore the effects and mechanisms of LIPUS on the mineralization of force-treated cementoblasts and its impact on OIIRR.

METHODS

We established a rat OIIRR model and locally administered LIPUS stimulation for 7 and 14 days. We analyzed root resorption volume, osteoclast differentiation, and the expression of osteocalcin and yes-associated protein 1 (YAP1) using micro-computed tomography (micro-CT), hematoxylin and eosin, tartrate-resistant acid phosphatase, immunofluorescence and immunohistochemistry staining. In vitro, we applied compressive force and LIPUS to the immortalized mouse cementoblasts (OCCM30). We assessed mineralization using alkaline phosphatase (ALP) staining, alizarin red staining, real-time quantitative polymerase chain reaction, Western blotting and immunofluorescence staining.

RESULTS

In rats, LIPUS reduced OIIRR, as evidenced by micro-CT analysis and histological staining. In vitro, LIPUS enhanced mineralization of force-treated OCCM30 cells, as indicated by ALP and alizarin red staining, upregulated mRNA expression of mineralization-related genes, and increased protein expression of mineralization markers. Mechanistically, LIPUS activated YAP1 signaling via the cytoskeleton-Lamin A/C pathway, supported by immunofluorescence and Western blot analysis.

CONCLUSION

This study demonstrates that LIPUS promotes mineralization in force-treated cementoblasts and reduces OIIRR by activating YAP1 through the cytoskeletal-Lamin A/C signaling pathway. These findings provide fresh insights into how LIPUS benefits orthodontic treatment and suggest potential strategies for preventing and treating OIIRR.

In vitro measurement of the initial forces and moments generated for a curve of Spee malocclusion with labial and lingual archwire forms

OBJECTIVES

To compare the biomechanics of labial and lingual fixed orthodontic treatment options for a simulated curve of Spee malocclusion.

MATERIALS AND METHODS

An in vitro electromechanical orthodontic simulator was used to measure the three-dimensional forces and moments on each tooth of a mandibular arch. Labial and lingual brackets, both with 0.018-inch slot sizes, were bonded to mechanical teeth. Three archwire forms were considered: labial straight, lingual straight, and lingual mushroom. The simulator was set in a passive levelled position with 0.016-inch × 0.022-inch stainless steel archwires, then teeth were moved to a curve of Spee maloclussion with the first premolar intruded 1.5 mm and the canine and second premolar intruded 0.75 mm. Two-way mixed multivariate analysis of variance (α = 0.05) was used to compare forces and moments generated among the three archwires.

RESULTS

Statistical differences were found in 55 of 63 comparisons of forces and moments between archwire types for each tooth around the arch. The lowest force magnitudes were measured for labial straight archwires at each tooth position. The lateral incisor experienced the largest gingival forces with all archwire forms. The first premolar and first molar experienced labial-lingual crown tipping moments in opposite directions between labial and the two lingual archwire forms.

CONCLUSIONS

Biomechanical differences between labial, lingual straight, and lingual mushroom treatment modalities for the correction of curve of Spee misalignments were elucidated. Labial straight archwire exerted the lowest force magnitudes overall. For both lingual archwire forms, the labial-lingual inclination of the first premolar could be highly variable during levelling.

The Potential Regulatory Role of Ferroptosis in Orthodontically Induced Inflammatory Root Resorption

People, in increasing numbers, are seeking orthodontic treatment to correct malocclusion, while some of them are suffering from orthodontically induced inflammatory root resorption (OIIRR). Recent evidence suggests that the immune-inflammatory response occurring during bone remodeling may be responsible for OIIRR. Ferroptosis, a new type of programmed cell death (PCD), has been found to have a close interrelation with inflammation during disease progression. While ferroptosis has been extensively studied in bone-related diseases, its role in OIIRR is poorly understood. Considering that the tooth root shares a lot of similar characteristics with bone, it is reasonable to hypothesize that ferroptosis contributes to the development of OIIRR. Nevertheless, direct evidence supporting this theory is currently lacking. In this review, we introduced ferroptosis and elucidated the mechanisms underlying orthodontic tooth movement (OTM) and OIIRR, with a special focus on the pivotal role inflammation plays in these processes. Additionally, we covered recent research exploring the connections between inflammation and ferroptosis. Lastly, we emphasized the important regulatory function of ferroptosis in bone homeostasis. Further investigations are required to clarify the modulation mechanisms of ferroptosis in OIIRR and to develop novel and potential therapeutic strategies for the management of OIIRR.

Reliability of information in YouTube™ videos on types of root resorption and related stimulating factors

BACKGROUND/AIM

Root resorption occurs for various reasons and can also be seen as a treatment complication in orthodontics. This study aimed to assess the reliability and quality of YouTube™ videos on root resorption and to assess whether the videos referred to orthodontic treatment and other stimulation factors.

MATERIALS AND METHODS

YouTube was searched using the keyword 'root resorption', which is the most searched term on Google Trends. The first 200 videos identified using the default filter 'sort by relevance' were used. Information such as the source, type, duration, and number of likes were recorded. Videos were analyzed using a 23-point content scale related to root resorption and divided into groups (poor, moderate, and excellent) based on the Global Quality Score.

RESULTS

A total of 95 videos were included in the study. Most were uploaded by dentists or dental clinics (n = 64, 67.4%). The mean number of days since upload was 1536 ± 1254, and the mean duration was 5 ± 4 min. The videos had a mean of 80 ± 515 likes and 7043 ± 35,382 views, and a mean viewing rate of 1131.71 ± 8736.83. The most discussed topic was radiographic signs of root resorption. While the highest content score for the videos was 21, the average score was only 4. The mean GQS was 2 ± 1. Grouping videos by GQS showed that 55 (57.9%) were poor, 38 (40%) were moderate, and 2 (2.1%) were excellent. There was a significant relationship between videos that mentioned orthodontics (n = 62; 65.3%) and higher GQS (p = .036), and a significant difference was between GQS groups for total content levels (p < .001).

CONCLUSIONS

YouTube videos related to root resorption lack sufficient information and clarity, and their quality needs to be improved. Oral health professionals should strive to produce higher-quality videos.

Root resorption in clear aligner treatment detected by CBCT: a Systematic review and Meta-analysis

OBJECTIVE

The aim of this study was to evaluate the amount of external apical root resorption in patients who had undergone orthodontic treatment with clear aligners evaluated using cone beam computed tomography.

METHODS

Studies that evaluated external apical root resorption before and after comprehensive orthodontic treatment with clear aligners were assessed by performing an electronic search from 5 databases comprising PubMed, SCOPUS, EBSCO, Cochrane Library, and LILACS and manual searches in the relevant journals and the reference lists of the included studies. Database search, elimination of duplicate studies, and data extraction were performed independently by 2 authors. The quality of the included studies was assessed using the Risk of Bias in Non-randomised Studies-of Interventions and the Cochrane Collaboration's Risk of Bias Tool. Studies that reported the tooth length or volume were used for quantitative analyses.

RESULTS

Nine studies were included in the meta-analysis. The overall root length after clear aligner treatment was significantly decreased compared with the pre-treatment length using cone beam computed tomography (mean differences = -0.56 mm, 95% confidence interval [-0.73, -0.38], P < .00001). However, only the maxillary central incisors, maxillary lateral incisors, and mandibular central incisors had significant reduction in root length. The meta-analysis from 3 studies also indicated that the root volume of the upper incisors also significantly decreased (mean differences = -13.34 mm3, 95% confidence interval [-16.57, -10.10], P < .00001).

CONCLUSIONS

Current evidence suggests that clear aligners can cause minimal root resorption. The highest amount of root resorption was observed in the maxillary central incisors.

Xanthohumol: Anti-Inflammatory Effects in Mechanically Stimulated Periodontal Ligament Stem Cells

BACKGROUND/OBJECTIVES

Initial sterile inflammation is an essential molecular process in the periodontium during orthodontic tooth movement. A better understanding and possible modulations of these processes are of great interest to develop individual therapies for special patient groups. The prenylated plant polyphenol xanthohumol (XN) could have modulating effects as it has shown anti-inflammatory and angiogenesis-inhibiting effects in various cell lines. This study investigated the anti-inflammatory properties of XN in an in vitro model of compressively stimulated human periodontal ligament stem cells (hPDLSCs), which have a different function in the periodontium than the previously used cementoblasts.

METHODS

The expression of inflammatory markers at the mRNA and protein levels and the regulation of central kinases were investigated.

RESULTS

XN showed a dose-dependent influence on cell viability. Low concentrations between 0.2 and 4 µM showed positive effects, while 8 µM caused a significant decrease in viability after 24 h. Mechanical stimulation induced an upregulation of pro-inflammatory gene (IL-6, COX2) and protein (IL-6) expression. Here, XN significantly reduced stimulation-related IL-6 mRNA and gene expression. Furthermore, the phosphorylation of AKT and ERK was upregulated by mechanical stimulation, and XN re-established phosphorylation at a level similar to the control.

CONCLUSIONS

We demonstrated a selective anti-inflammatory effect of XN in hPDLSCs. These findings provide the basis for further investigation of XN in the modulation of inflammatory responses in orthodontic therapy and the treatment of periodontal inflammation.

Factors affecting external apical root resorption of maxillary incisors associated with microimplant-assisted rapid palatal expansion

Objective

To measure and compare the extent of root resorption in the maxillary incisors following microimplant-assisted rapid palatal expansion (MARPE) and to identify risk factors of root resorption after expansion.

Methods

Cone-beam computed tomography images were obtained from a total of 60 patients both before expansion (T1) and 3 to 6 months after expansion (T2). Measurements taken included tooth length, root length, crown length and center of resistance. Resorption length (RL) and resorption length percentage (RLp), resorption volume (RV) and resorption volume percentage (RVp) and the amount of expansion were calculated.

Results

A significant difference in tooth length and volume was observed in both the central and lateral incisors before and after expansion. The resorption index (RL, RLp, RV, RVp) was significantly higher in the central incisors than in the lateral incisor. There was a significant correlation between several factors: age and RLp of the central incisors, the amount of expansion and RVp of the central incisors, tooth length of the central incisors and RL, RLp of the central incisors, root/crown ratio of the central incisors and RL of the central incisors, as well as tooth length of the lateral incisors and the RL of the lateral incisors.

Conclusions

Significant root resorption occurs in maxillary incisors following MARPE, with central incisors root resorption being significantly higher than lateral incisors. Key risk factors for root resorption after MARPE include advanced age, a larger amount of expansion, initial tooth length, and a root/crown ratio.

Factors that may increase the risk of external apical root resorption during orthodontic treatment : Retrospective clinical investigation

PURPOSE

To determine the correlation between external apical root resorption and malocclusion-related variables in patients treated with fixed orthodontic appliances.

METHODS

In all, 103 patients aged 12-15 years and treated with edge-wise appliances either without extractions or with four premolar extractions were included in this retrospective cohort study. External apical root resorption was assessed in the pre- and posttreatment panoramic radiographs of these patients for incisors, canines, premolars, and first molars. A total of 2332 teeth were evaluated in 206 panoramic radiographs obtained from 103 patients. The gender of the patients, duration of orthodontic treatments, presence of premolar extractions, Angle classification, overbite, overjet and amount of crowding were assessed. Wilcoxon signed-rank test, Mann-Whitney U test, and Kruskal-Wallis test were used for statistical analysis of the data.

RESULTS

Statistically significant (p < 0.001) root resorption occurred in all examined teeth during orthodontic treatment. The degree of root resorption observed in the premolars was significantly greater in premolar extraction cases than in nonextraction cases. Statistically significant negative correlations were found between the degree of root resorption of the maxillary lateral teeth and between the maxillary first premolar teeth and the amount of maxillary crowding.

CONCLUSIONS

The orthodontic treatment protocols and the amount of tooth movements achieved were shown to be dependent on the severity of dental malocclusions and they have an influence on the amount of external apical root resorption that occurs during the course of orthodontic treatment.

Comparative Experimental Evaluation of Orthodontic Appliances for Maxillary Arch Expansion

Background/Objectives: The orthodontic treatment of posterior crossbite using appliances for gradual maxillary expansion is crucial to ensure proper transversal jaw relationships as much as occlusal functionality. The aim of this study was to analyze forces and torques generated by different appliances for maxillary expansion. Methods: Measurements were conducted for the Wilson® 3D® Quadhelix (WQH) and Wilson® 3D® Multi-Action Palatal Appliance (WPA) across various sizes and compared to the Remanium® Quadhelix (RQH). Activations were set to 8 mm for the WQH and RQH and 6 and 8 mm for the WPA. Rotations and root torque were simulated via an activation of 10° for arches. A total of eight test series were conducted. Results: The WPA displayed the highest force and torque values for all movements, far surpassing recommended guideline values (expansion 8.5->15.0 N/46.3-86.5 Nmm, rotation 3.1-6.1 N/40.7-61.4 Nmm, torque 3.9-5.1 N/22.4-29.7 Nmm), and the WQH displayed the lowest values (expansion 2.7-12.6 N/11.1-39.6 Nmm, rotation 0.1-1.7 N/23.0-32.2 Nmm, torque 0.9-2.9 N/3.4-10.5 Nmm). Appliances with the smallest transverse dimensions exhibited the highest force and torque maxima. Conclusions: This study underscores the importance of understanding biomechanical principles in orthodontics for minimizing unintended tooth movements, providing detailed insights into the force systems of appliances acting in the transverse plane, and establishing a foundation for future clinical investigations to validate these in vitro findings.

CREB3L1 deficiency impairs odontoblastic differentiation and molar dentin deposition partially through the TMEM30B

Odontoblasts are primarily responsible for synthesizing and secreting extracellular matrix proteins, which are crucial for dentinogenesis. Our previous single-cell profile and RNAscope for odontoblast lineage revealed that cyclic adenosine monophosphate responsive element-binding protein 3 like 1 (Creb3l1) was specifically enriched in the terminal differentiated odontoblasts. In this study, deletion of Creb3l1 in the Wnt1+ lineage led to insufficient root elongation and dentin deposition. Assay for transposase-accessible chromatin with high-throughput sequencing (ATAC-seq) and RNA sequencing were performed to revealed that in CREB3L1-deficient mouse dental papilla cells (mDPCs), the genes near the closed chromatin regions were mainly associated with mesenchymal development and the downregulated genes were primarily related to biological processes including cell differentiation, protein biosynthesis and transport, all of which were evidenced by a diminished ability of odontoblastic differentiation, a significant reduction in intracellular proteins, and an even greater decline in extracellular supernatant proteins. Dentin matrix protein 1 (Dmp1), dentin sialophosphoprotein (Dspp), and transmembrane protein 30B (Tmem30b) were identified as direct transcriptional regulatory targets. TMEM30B was intensively expressed in the differentiated odontoblasts, and exhibited a significant decline in both CREB3L1-deficient odontoblasts in vivo and in vitro. Deletion of Tmem30b impaired the ability of odontoblastic differentiation, protein synthesis, and protein secretion in mDPCs. Moreover, overexpressing TMEM30B in CREB3L1-deficient mDPCs partially rescued the extracellular proteins secretion. Collectively, our findings suggest that CREB3L1 participates in dentinogenesis and facilitates odontoblastic differentiation by directly enhancing the transcription of Dmp1, Dspp, and other differentiation-related genes and indirectly promoting protein secretion partially via TMEM30B.

Does the Timing of Orthognathic Surgery Affect the Level of External Root Resorption?: Surgery-First Approach Versus Conventional Orthognathic Surgery

OBJECTIVE

This study aimed to compare external root resorption levels, both linearly and areally, on panoramic radiographs in Class III patients whose treatment was completed with the conventional orthognathic surgery and the surgery-first approach.

METHODS

The study included 20 patients (10 female, 10 male; 23.98±2.63 y) treated with conventional orthognathic surgery and 18 patients (8 female, 10 male; 27.5±3.42 y) treated with surgery-first approach was included. Linear and area measurements were made on the digital panoramic radiographs taken before and at the end of the treatment of 38 patients who constituted the sample of the study. The mean changes observed in each group were evaluated using a paired t test. The chronological ages, skeletal features (type of Class III malocclusion), treatment durations, initial values, and mean changes that occurred in each group were compared using independent t test.

RESULTS

When the changes in root lengths and root surface areas were evaluated in all teeth in both groups, a significant loss in size was measured (P<0.001). More resorption was observed in teeth 12 and 22 in the conventional surgery group (P<0.05). When the amount of resorption in both groups was compared, there was significantly more resorption in tooth number 12 in the conventional surgery group (P<0.05).

CONCLUSION

The study showed that there was external root resorption in all teeth in both protocols, but the root lengths of the lateral teeth were shortened more in both groups.

Exploring etiologic contributions to the occurrence of external apical root resorption

INTRODUCTION

External apical root resorption (EARR) is often an undesirable sequela of orthodontic treatment. Prior studies have suggested a substantial link between EARR and certain genetic components. Single nucleotide polymorphisms (SNPs) may play a role as predisposing factors. This study aimed to investigate the potential association between EARR and various SNPs.

METHODS

The study included 218 orthodontic participants of all malocclusions who had available pretreatment and posttreatment panoramic radiographs. The most severely affected maxillary incisor on the radiograph was assessed for EARR using a 0-4 categorical scale. DNA was taken from the saliva samples of the participants, and the SNPs were analyzed using polymerase chain reaction and TaqMan chemistry. Statistical testing was performed to verify any associations with EARR (P <0.05).

RESULTS

From all genes tested, the rs678397 SNP of ACT3N (P = 0.003) and the rs1051771 SNP of TSC2 (P = 0.03) were significantly associated with EARR. No association could be established between other polymorphisms and EARR. In addition, patients with Class III malocclusion and extended treatment times were at increased risk of developing EARR.

CONCLUSIONS

Our results support the concept of gene polymorphisms as risk factors in EARR. In particular, a significant association was found between ACT3N and TSC2 and EARR. Clinically, predisposing risk factors for EARR should be assessed for each patient.

Panoramic evaluation of external root resorption in mandibular molars during orthodontic treatment: a comparison between root-filled and vital teeth treated with fixed appliances or clear aligners

BACKGROUND

This investigation compared the extent of external apical root resorption (EARR) in root-filled teeth (RFT) and their contralateral vital pulp teeth (VPT) counterparts during orthodontic treatment (OT) with clear aligner (CA) treatment or fixed appliance (FA) treatment.

METHODS

Sixty-six patients with similar baseline American Board of Orthodontics (ABO) discrepancy index scores were divided into two groups: 37 patients (21 females, 16 males; mean age 17.45 ± 2.67 years) in the FA group, and 29 patients (18 females, 11 males; mean age 18.33 ± 1.96 years) in the CA group. Digital panoramic radiographs captured pre- and post-OT were used to measure tooth lengths and root surface measurements in mandibular molars. EARR in both RFT and contralateral VPT was evaluated pre- and post-OT. Statistical analysis employed paired t-tests, independent t-tests, and analysis of covariance (ANCOVA) (p < .05).

RESULTS

All teeth exhibited varying degrees of EARR following OT. FA treatment resulted in significantly longer treatment duration (p < .05) and greater EARR compared to CA treatment (p < .05). Moreover, statistically significant differences in EARR were observed within both groups between RFT and VPT (p < .05).

CONCLUSIONS

Comparison of pre- and post-OT radiographs revealed different degrees of EARR in all teeth. CA treatment resulted in less frequent and less severe EARR compared to FA treatment. RFT demonstrated greater resistance to EARR than VPT in both treatment groups.

The orthodontic-endodontic interface: trauma and pulpal considerations

The interpretation of the clinical signs and symptoms arising from the interdisciplinary relationship between orthodontics and endodontics becomes more complicated when superimposed by dental trauma. A history of dental trauma before or during orthodontic tooth movement may have implications for pulpal health and clinical outcomes. An understanding of the biology is essential for appropriate treatment planning. This review and treatment recommendations will assist dental practitioners in managing orthodontic-endodontic interactions.

Inhibition of 12/15-lipoxygenase reduces orthodontically induced root resorption in rats

OBJECTIVES

To investigate whether the inhibition of 12/15-lipoxygenase (12/15-LOX), one of the core enzymes of the arachidonic acid cascade, suppresses orthodontically induced root resorption (OIRR), and examine the involvement of the hyaline degeneration of periodontal ligament cells and odontoclast differentiation.

MATERIALS AND METHODS

The left maxillary first molars of 10-week-old male Wistar rats were moved mesially for 14 days using a closed-coil spring (25 cN) inserted between the first molar and incisor. The rats were intraperitoneally administered with a 12/15-LOX specific inhibitor (ML-351; 0.05 mmol/kg) daily in the experimental group or vehicle (dimethyl sulfoxide) in the control group. Tooth movement was measured using microcomputed tomography on day 14. The appearance of OIRR, hyaline degeneration, osteoclasts, and odontoclasts was evaluated via histological analysis. Immunohistochemical staining for receptor-activated NF-kB ligand (RANKL) and osteoprotegerin was performed.

RESULTS

OIRR observed on day 14 in the control group was strongly suppressed by ML-351 treatment. Hyaline degeneration observed on the compression side on day 3 and the appearance of osteoclasts and odontoclasts on days 3 and 14 were significantly suppressed by ML-351. RANKL expression on day 3 was significantly suppressed by ML-351. These key processes in OIRR were substantially suppressed by ML-351 treatment.

CONCLUSIONS

Inhibition of 12/15-LOX reduced OIRR by suppressing hyaline degeneration and subsequent odontoclast differentiation.

Reliability and agreement of root length measurements during orthodontic treatment in images from different CBCT machines using multiplanar reconstruction

Objectives

To assess inter- and intrarater reliability and agreement for measurements of root lengths using multiplanar reconstruction (MPR) in cone beam computed tomography (CBCT) examinations.Furthermore, to determine whether using MPR from different CBCT machines was a reliable and reproducible method for assessment of root length during orthodontic treatment of adolescents.

Materials and methods

A total of 40 CBCT examinations obtained before, during and after orthodontic treatment of 14 adolescents, with fixed appliances from a multicentre randomised controlled trial, were used. All roots from the incisors to the first molars were measured by two independent raters and in accordance with a protocol preceded by a multi-step calibration. Reliability was assessed by intra class correlation (ICC). Agreement was assessed by measurement error according to the Dahlberg formula and Bland-Altman plot.

Results

The number of repeated measurements varied from 436 to 474 for the different timepoints. Good to excellent inter- and intrarater reliability for different tooth groups and timepoints were shown. Measurement error for inter- and intrarater agreement varied between 0.41 mm and 0.77 mm. The Bland-Altman plot with 95% limits of agreement varied between +1.43 mm and -2.01 mm for different tooth groups and timepoints.

Conclusions

The results of this study indicate that CBCT using MPR from different machines is a reproducible method for measuring root length during different phases of orthodontic treatment. When interpreting root shortening measurements in CBCT using MPR for clinical or research purposes, values below 2 mm should be approached with caution, as they may contain measurement errors.

CBCT Evaluation of Alveolar Bone Change and Root Resorption after Orthodontic Treatment: A Retrospective Study

BACKGROUND

For years, there has been a long debate about the impact of orthodontic treatment on the periodontium of patients. Therefore, it is important to understand the effects of orthodontic forces on the periodontium. The objective of this study was to evaluate the height of the alveolar bone at the four surfaces of specific teeth and the root length of the central incisors before and after orthodontic treatment.

MATERIALS AND METHODS

CBCTs from a group of fifty patients were evaluated before (T0) and after orthodontic treatment (T1). Evaluations of the alveolar bone were performed by measuring the distance from the most apical point of the marginal portion to the CEJ at the buccal (B-ABL), lingual (L-ABL), mesial (M-ABL), and distal (D-ABL) surfaces of the central incisor (CI), first premolar (1st PM), and first molar (1st M). Meanwhile, root resorptions were evaluated by measuring the distance from the center of the tooth at the CEJ to the most apical point of the central incisor.

RESULTS

The reduction in the alveolar bone level was highest at the buccal segment (75%) and lowest at the distal (42%) segment, although the decrease was not statistically significant. Root resorption, in terms of reduction in the total length, was detected in the upper central incisor.

CONCLUSIONS

Fixed orthodontic treatment can produce a significant reduction in root length, but not at the level of the alveolar bone.

Prognostic risk factors for apical root resorption in orthodontic patients - Are the Kjær's morphologic characteristics of clinical relevance?

BACKGROUND

Patients undergoing orthodontic treatment (OT) face an increased risk of developing external apical root resorption (EARR). A prognostic risk assessment prior to OT can potentially be conducted through anatomical features in panoramic radiography. This retrospective study aimed to assess the significance of Kjær's morphological characteristics in analyzing the risk of EARR.

METHODS

Panoramic radiographs of 1,156 patients (624 females, 532 males) were retrospectively analyzed. Anamnestic and treatment-related data were extracted from patient records. The mean age at the start of OT was 12.8 ± 2.2 years (min. 6.4 years, max. 22.3 years) and at the end of OT 15.9 years (min. 8.5 years, max. 24.1 years). The mean treatment duration was 3.1 ± 1.6 years. Panoramic radiographs with a minimum of two per patient were examined for the presence of Kjær's characteristics. The degree of EARR was registered defining resorption in four degrees of severity. Bivariate analysis and multivariate Poisson regression were performed to assess the association between Kjær's characteristics and EARR patient- and tooth- related (α = 0.05).

RESULTS

In total, 72.8% of the patients showed EARR at the end of OT with lateral maxillary incisors most frequently affected. Short roots (p < 0.001) were significantly associated with EARR in patients. Tooth-related microdontia (#12, #22, lower second premolars), narrow crowns (#11, #21, lower incisors), short roots (upper incisors, lower first molars) and ectopia (#11, #21, #13), such as shorter distal roots of the mandibular first molar showed a significant association with EARR depending on severity degree. The type of orthodontic appliance (fixed: p < 0.001, fixed and removeable: p = 0.008), as well as treatment duration (p < 0.001) were also identified as risk factors for EARR.

CONCLUSIONS

Although the risk assessment for EARR development through panoramic radiography analysis is limited, predisposition appears to be present in specific dental characteristics and treatment-related factors.

An Automatic Grading System for Orthodontically Induced External Root Resorption Based on Deep Convolutional Neural Network

Orthodontically induced external root resorption (OIERR) is a common complication of orthodontic treatments. Accurate OIERR grading is crucial for clinical intervention. This study aimed to evaluate six deep convolutional neural networks (CNNs) for performing OIERR grading on tooth slices to construct an automatic grading system for OIERR. A total of 2146 tooth slices of different OIERR grades were collected and preprocessed. Six pre-trained CNNs (EfficientNet-B1, EfficientNet-B2, EfficientNet-B3, EfficientNet-B4, EfficientNet-B5, and MobileNet-V3) were trained and validated on the pre-processed images based on four different cross-validation methods. The performances of the CNNs on a test set were evaluated and compared with those of orthodontists. The gradient-weighted class activation mapping (Grad-CAM) technique was used to explore the area of maximum impact on the model decisions in the tooth slices. The six CNN models performed remarkably well in OIERR grading, with a mean accuracy of 0.92, surpassing that of the orthodontists (mean accuracy of 0.82). EfficientNet-B4 trained with fivefold cross-validation emerged as the final OIERR grading system, with a high accuracy of 0.94. Grad-CAM revealed that the apical region had the greatest effect on the OIERR grading system. The six CNNs demonstrated excellent OIERR grading and outperformed orthodontists. The proposed OIERR grading system holds potential as a reliable diagnostic support for orthodontists in clinical practice.

Effectiveness of different intrusion modes of maxillary anterior teeth with mini-implants in clear aligner treatment: a three-dimensional finite element analysis

BACKGROUND

The intrusion of maxillary anterior teeth is often required and there are various intrusion modes with mini-implants in clear aligner treatment. The objective of this study was to evaluate the effectiveness of maxillary anterior teeth intrusion with different intrusion modes, aiming to provide references for precise and safe intrusion movements in clinical practice.

METHODS

Cone-beam computed tomography and intraoral optical scanning data of a patient were collected. Finite element models of the maxilla, maxillary dentition, periodontal ligaments (PDLs), clear aligner (CA), attachments, and mini-implants were established. Different intrusion modes of the maxillary anterior teeth were simulated by changing the mini-implant site (between central incisors, between central and lateral incisor, between lateral incisor and canine), loading site (between central incisors, on central incisor, between central and lateral incisor, between lateral incisor and canine), and loading mode (labial loading and labiolingual loading). Ten conditions were generated and intrusive forces of 100 g were applied totally. Then displacement tendency of the maxillary anterior teeth and CA, and stress of the PDLs were analyzed.

RESULTS

For the central incisor under condition L14 and for the canine under conditions L11, L13, L23, and L33, the intrusion amount was negative. Under other conditions, the intrusion amount was positive. The labiolingual angulation of maxillary anterior teeth exhibited positive changes under all conditions, with greater changes under linguoincisal loading. The mesiodistal angulation of canine exhibited positive changes under labial loading, while negative changes under linguoincisal loading except for condition L14.

CONCLUSIONS

The intrusion amount, labiolingual and mesiodistal angulations of the maxillary anterior teeth were affected by the mini-implant site, loading site, and loading mode. Labial and linguoincisal loading may have opposite effects on the intrusion amount of maxillary anterior teeth and the mesiodistal angulation of canine. The labiolingual angulation of the maxillary incisors would increase under all intrusion modes, with greater increases under linguoincisal loading.

Effect of Orthodontic Treatment on Endodontically Treated Teeth

Background

This research has been conducted to assess the effect of orthodontic treatment on endodontically treated tooth.

Materials and Methods

Overall, fifty subjects had been recruited. The participants received root canal therapy within 3 months as well as had an appointment for fixed orthodontic therapy. All candidates underwent an intraoral investigation. Radiographic evaluation as well as therapy planning were completed. Fixed orthodontic therapy had been initiated. All of the participants had been recalled. Endodontically restored teeth had been evaluated. All outcomes were assessed via Statistical Package for the Social Sciences (SPSS) software.

Results

In this study, there were 25 males and 25 females. Pulp stones were seen in 15 subjects. Apical periodontitis was seen in nine subjects. Apical root resorption was seen in seven subjects, and enamel decalcification was seen in four subjects. Overall, 35 out of 50 subjects showed negative effects of orthodontic treatment on endodontically treated teeth.

Conclusion

Excessive orthodontic force may result in increased pulp and peri-apical inflammation.

A bibliometric analysis of the 100 top-cited systematic review and meta-analysis in Orthodontics

OBJECTIVE

This bibliometric study aimed to analyze the citation metrics, journal and author characteristics, and subject domains of the 100 top-cited Systematic Reviews (SR) and Meta-Analysis (MA) in orthodontics.

MATERIAL AND METHODS

An electronic database search was conducted for SR and MA in the Web of Science on 16th July 2023, without language and time restrictions. Of the 802 hits returned, the 100 top-cited orthodontic articles were shortlisted. They were analyzed for citation metrics, journal characteristics (journal, year of publication, impact factor-IF), author and affiliation characteristics (number, primary and corresponding author's affiliation, and country), study domain, and keywords.

RESULTS

These articles were published from 1996 to 2021 in 20 journals, with an impact factor of 1.9 to 10.5, by 351 researchers affiliated with 104 universities. Their citations ranged from 45 to 344, and 34 poised to be classified as classic (≥ 100 citations). The maximum number of articles was published in the American Journal of Orthodontics and Dentofacial Orthopedics (n=38), the European Journal of Orthodontics (n=18), and the Angle Orthodontist (n=8). The authors for individual papers ranged from 1 to 10, with 5 being the most common (n=58). Europe had the highest contribution regarding the number of corresponding authors, institutions, and citations. Bone anchorage and orthodontic tooth movement/Biomechanics were the most frequently researched domains (n=11 each). The most common keyword used was Orthodontics (n=19), followed by Systematic Review (n=16) and Meta-analysis (n=9).

CONCLUSION

In general, the top cited SR and MA were published in high-impact orthodontic journals, were multi-authored, and reflected the collaborative work from different universities.

Periodontal considerations during orthodontic intrusion and extrusion in healthy and reduced periodontium

In patients with advanced periodontal disease, pathological tooth migration may occur, which may require subsequent orthodontic treatment for both aesthetic and functional purposes. When planning orthodontic treatment mechanics, intrusive or extrusive forces are frequently indicated. Understanding tissue reactions during these movements is essential for clinicians when devising a comprehensive orthodontic-periodontal treatment plan. This knowledge enables clinicians to be fully aware of and account for the potential effects on the surrounding tissues. The majority of our understanding regarding the behavior of periodontal tissues in both healthy and compromised periodontal conditions is derived from animal studies. These studies offer the advantage of conducting histological and other assessments that would not be feasible in human research. Human studies are nevertheless invaluable in being able to understand the clinically relevant response elicited by the periodontal tissues following orthodontic tooth movement. Animal and human data show that in dentitions with reduced periodontal support, orthodontic intrusion of the teeth does not induce periodontal damage, provided the periodontal tissues do not have inflammation and plaque control with excellent oral hygiene is maintained. On the contrary, when inflammation is not fully controlled, orthodontic intrusion may accelerate the progression of periodontal destruction, with bacterial plaque remnants being displaced subgingivally, leading to further loss of attachment. Orthodontic extrusion, on the other hand, does not seem to cause further periodontal breakdown in dentitions with reduced periodontal support, even in cases with deficient plaque control. This is attributed to the nature of the tooth movement, which directs any plaque remnants coronally (supragingivally), reducing the risk of adverse effects on the periodontal tissues. This specific type of tooth movement can be leveraged to benefit periodontal conditions by facilitating the regeneration of lost hard and soft periodontal tissues in a coronal direction. As a result, orthodontic extrusion can be employed in implant site development, offering an advantageous alternative to more invasive surgical procedures like bone grafting. Regardless of the tooth movement prescribed, when periodontal involvement is present, it is essential to prioritize periodontal therapy before commencing orthodontic treatment. Adequate plaque control is also imperative for successful outcomes. Additionally, utilizing light orthodontic forces is advisable to achieve efficient tooth movement while minimizing the risk of adverse effects, notably root resorption. By adhering to these principles, a more favorable and effective combined orthodontic-periodontal approach can be ensured. The present article describes indications, mechanisms, side effects, and histological and clinical evidence supporting orthodontic extrusion and intrusion in intact and reduced periodontal conditions.

Characteristics of Orthodontic Treatment in Cancer Survivors: A Systematic Review

Background: Survival rates of cancer patients have increased globally and across age groups. Challenges arising from craniofacial growth-development disturbances and dental abnormalities might warrant modifications to standard orthodontic pathways of care. Objective: The aim of this study was to systematically summarize and critically assess the available literature regarding the characteristics of orthodontic treatment in cancer survivors. Materials and Methods: A systematic search was conducted in seven databases for studies on malignant tumor survivors having undergone orthodontic intervention with fixed appliances following cancer treatment up to August 2023. The outcomes of interest included quantitative data regarding various characteristics of orthodontic treatment and the post-treatment period. The risk of bias was assessed individually with the Newcastle-Ottawa scale. Results: Out of 347 records, 4 cohort studies were eventually included in the qualitative synthesis. Leukemia was the most common malignancy type, with treatment involving mainly chemotherapy and/or radiotherapy. The duration of orthodontic treatment in cancer survivors varied. Occlusal results, quality of life, and satisfaction were comparable to healthy peers. However, in some survivors' groups, treatment was shorter and the final results were compromised. Root resorption and oral mucositis were reported among the treated cancer survivors. Reduced occlusal outcome stability during the retention period was also reported. Conclusions: Overall, the duration of orthodontic treatment varied among cancer survivors. The occlusal results achieved were similar to those of their healthy peers, though potentially less stable. Patient-reported outcomes did not differ significantly between cancer survivors and healthy individuals treated orthodontically.

Tooth movement with dental anchorage vs. skeletal anchorage: A systematic review of clinical trials

The aim of this study is to compare the time and movement of orthodontic treatment using dental anchorage and skeletal anchorage in adolescent and adult patients with dental malocclusions. A systematic search was conducted in the Embase, PubMed, Lilacs, Cochrane, Trip, and Scopus databases up to October 2022. All the articles were selected using title and abstract, applying the inclusion and exclusion criteria. Disagreements were resolved with a third author. Finally, a full-text selection took place. The data extraction was conducted by two authors who independently evaluated the risk of bias. The methodological quality of the randomized clinical trials was evaluated using the Cochrane tool for the evaluation of the randomized clinical trials. Six articles were included in the data analysis. There were four clinical trials and two randomized clinical trials. A total of 176 patients was obtained with an age range between 14 and 46 years. Four studies showed significant differences when comparing the two anchorages in retraction or distalization of tooth groups, and two showed no differences when using dental and skeletal anchorage for vertical movements; only the articles with vertical movements showed relapse. We can conclude that skeletal anchorage generates precise and stable horizontal movements without overloading or changing the position of the molar. Future studies must incorporate three-dimensional technology for greater clinical accuracy.

An evaluation of root resorption associated with the use of photobiomodulation during orthodontic treatment with clear aligners: a retrospective cohort pilot study

OBJECTIVES

To evaluate the change in tooth root volume using cone-beam computed tomography (CBCT) in a group of patients treated concurrently with clear aligners and an adjunctive photobiomodulation (PBM) device.

MATERIALS AND METHODS

This retrospective cohort pilot study included the records of 32 consecutively treated clear aligner patients (23 female, 9 male) from the private practice of one orthodontist. The PBM group (n = 16) used the device once per day for 5 minutes per arch and was compared with a matched control group (n = 16). A semiautomated segmentation technique was used to obtain tooth volume of anterior teeth from CBCT imaging prior to (T0) and during or immediately following (T1) orthodontic treatment with clear aligners. The change in root volume between time points was assessed.

RESULTS

There was no statistically significant difference between the pre- and posttreatment root volumes of maxillary and mandibular anterior teeth, regardless of which intervention group the patient belonged to (P > .05). There was also no difference in the mean percentage change in root volume between clear aligner patients in this study who were treated with the PBM device compared with a matched control group (P > .05).

CONCLUSIONS

Clear aligner patients in this study who changed their aligners every 3 to 5 days and used adjunctive photobiomodulation therapy did not experience clinically relevant orthodontically induced external root resorption. Due to the small sample size and measurement error in the root segmentation process, the results should be interpreted with caution.

Evaluation of the use of a clinical practice guideline for external apical root resorption among orthodontists

BACKGROUND

External apical root resorption (EARR) is a frequently observed adverse event in patients undergoing fixed appliance therapy. Assessing the patients' risk during treatment is important, as certain factors are assumed to be associated with an increased likelihood of occurrence. However, their predictive value remains limited, making evidence-based clinical decision-making challenging for orthodontists. To address this issue, the Dutch Association of Orthodontists (NvVO) developed a clinical practice guideline (CPG) for EARR in accordance with the AGREE II instrument (Appraisal of Guidelines for Research and Evaluation II) in 2018. The aim of this study is to get insight into the actual utilization and the practical implementation of the guideline among orthodontists. The hypothesis to be tested was that after its introduction, clinical practice for EARR has changed towards the recommendations in the CPG.

OBJECTIVE

To investigate the use of the 2018 clinical practice guidelines for EARR among orthodontists 3 years after its introduction.

METHODS

A questionnaire using a 7-point Likert scale was developed concerning four domains of EARR described in the guideline. The questionnaire was piloted, finalised, and then distributed digitally among Dutch orthodontists. REDCap was used for data collection, starting with an invitation email in June 2021, followed by two reminders. Effect was tested by the Mann-Whitney U test, and the influence of demographic variables was analysed.

RESULTS

Questionnaires were sent out to all 275 and completed by 133 (response rate 48%); N = 59 females and N = 73 males were included; 81% had their training in the Netherlands, 89% had ≥ 6 years of work experience, and 89% worked in private orthodontic practice. One hundred thirty orthodontists (98.5%) reported changes in clinical practice. The biggest positive change in clinical behaviour regarding EARR occurred if EARR was diagnosed during treatment. Sex, clinical experience, country of specialist training, and working environment of the respondents did not affect clinical practices regarding EARR.

CONCLUSIONS

This questionnaire demonstrated that, 3 years after introduction of the guideline, orthodontists improved their self-reported clinical practices to a more standardised management of root resorption. None of the demographic predictors had a significant effect on the results.

Enhancing Surgical Outcomes via Three-Dimensional-Assisted Techniques Combined with Orthognathic Treatment: A Case Series Study of Skeletal Class III Malocclusions

(•) Orthognathic surgery is a necessary procedure for the correction of severe skeletal discrepancies, among which are skeletal Class III malocclusions. Currently, both conventional fixed braces and clear aligners can be used in orthognathic surgery. However, the use of clear aligners remains a little-chosen option. The present study aimed to evaluate the skeletal and aesthetic improvements in adults with Class III malocclusion after surgical treatment and compare the results achieved by fixed appliances versus clear aligners. The study sample included four patients (three males and one female, aged 18 to 34 years) with skeletal Class III malocclusion, three of whom underwent a bimaxillary surgery and one of whom underwent only a bilateral sagittal split osteotomy. Two patients were treated with fixed appliances and two with clear aligners. The pre- and post-surgical hard and soft tissue cephalometric measurements were performed and compared for each patient and between fixed appliances and clear aligners. One year after surgery, all patients showed an essential modification of the face’s middle and lower third with an increase in the convexity of the profile and the Wits index and a reduction in the FH^NB angle. No differences were noted between fixed appliances and aligners. Therefore, thanks to the 3D-assisted surgery associated with orthodontics, every participant achieved proper occlusal function and an improved facial aesthetics. In addition, the clear aligners can be considered a valid alternative for pre- and post-surgical orthodontic treatment.

Evaluation of Aligners and Root Resorption: An Overview of Systematic Reviews

Background: To evaluate the current evidence on clear aligners and root resorption using 3D and/or combined 2D and 3D methods from available systematic reviews and meta-analyses and to determine the relationship between root resorption and clear aligners using the AMSTAR 2 tool. Methods: A comprehensive literature search of systematic reviews investigating aligners and root resorption, published up until 31 December 2022, was conducted. The following electronic databases were searched: MEDLINE via PubMed, EMBASE, Google Scholar, Science Direct, Web of Science, Scopus, LIVIVO, and LILACS. There were no language restrictions. The inclusion criteria were restricted to studies focusing on root resorption utilizing either 3D methods exclusively or a combination of 2D and 3D techniques. Data were screened and analyzed for quality using the "A Measurement Tool to Assess Systematic Reviews (AMSTAR 2)" tool. Data extraction was conducted independently by two authors. The gathered information was categorized and synthesized narratively based on the primary findings elucidated within the reviews. Results: Out of a total of 1221 potentially eligible studies initially identified, 4 systematic reviews met the inclusion criteria following the exclusion of irrelevant studies. Among these, two systematic reviews (50%) were classified as low-quality, while the remaining two (50%) were deemed to be of critically low quality. Conclusions: Based on the findings of four systematic reviews, the root resorption rate was lower with the use of clear aligners than with fixed aligners. It is advisable to approach the interpretation of this conclusion with caution, as the quality of the available evidence is assessed to be very low. Higher quality systematic reviews are needed to substantiate this conclusion.

Effects of premolar extraction and orthodontic treatment in adolescents - a retrospective cephalometric study

OBJECTIVES

To evaluate the cephalometric effects of premolar extraction on skeletal and dental parameters, and on the soft tissues, in patients subsequently treated with fixed appliances. Prevalence and severity of external apical root resorption due to premolar extraction were also examined.

MATERIALS AND METHODS

The dental records of 79 patients treated with fixed appliances were retrieved (groups: extraction, n = 19; non-extraction, n = 60). Pre- and post-treatment statuses of skeletal, dentoalveolar, and soft tissue variables were analyzed on lateral cephalograms to determine change. Periapical radiographs of the maxillary incisors were assessed for external apical root resorption using the Levander & Malmgren index. The t-test, Mann-Whitney U test, chi-squared test, and Kruskal-Wallis test were used to analyze the data. Significance was set at p < .05.

RESULTS

Changes in the protrusion and proclination of the incisors and in lip position were significantly different between the groups. Prevalence of external apical root resorption in the two groups was similar.

CONCLUSIONS

Our findings suggest that extraction therapy affects dentoalveolar traits but not jaw position, nor the risk of root resorption, in patients treated with fixed appliances.

A newly developed kit for dental apical root resorption detection: efficacy and acceptability

OBJECTIVES

To determine the efficacy of a newly developed kit in dentine sialophosphoprotein (DSPP) detection and compare it with enzyme-linked immunosorbent assay (ELISA). User acceptance was also determined.

MATERIALS AND METHODS

This cross-sectional study consisted of 45 subjects who were divided into 3 groups based on the severity of root resorption using radiographs: normal (RO), mild (RM), and severe (RS). DSPP in GCF samples was analyzed using both methods. Questionnaires were distributed to 30 orthodontists to evaluate future user acceptance.

RESULTS

The sensitivity and specificity of the kit were 0.98 and 0.8 respectively. The DSPP concentrations measured using ELISA were the highest in the RS group (6.33 ± 0.85 ng/mL) followed by RM group (3.77 ± 0.36 ng/mL) and the RO group had the lowest concentration (2.23 ± 0.55 ng/mL). The new kit portrayed similar results as the ELISA, the optical density (OD) values were the highest in the RS group (0.62 ± 0.10) followed by RM group (0.33 ± 0.03) and the RO group (0.19 ± 0.06). The differences among all the groups were statistically significant (p < 0.05) for both methods. The Pearson correlation coefficient showed a statistically significant (p < 0.001) strong and positive correlation between DSPP concentrations and OD values.

CONCLUSIONS

The new kit was validated to detect the colour intensities of different severity of root resorptions. Most of the responses to the survey were positive towards the new kit for being a safer and simpler method to detect apical root resorption.

Effects of continuous and released compressive force on osteoclastogenesis invitro

Objective

Compressive force has been found to be catabolic to alveolar bone during orthodontic tooth movement. This study quantified the fusion of mononuclear RAW 264.7 cells (a murine osteoclastic-like cell line) into multinucleated osteoclasts under a hydrostatic pressure-generated mechanical compression-the new model of various magnitudes and durations.

Methods

RAW 264.7 cells were subjected to 0.3, 0.6 or 0.9 g/cm2 of compressive force by an acrylic cylinder custom-made by laser cutting or no compressive force for 4 days during osteoclastogenic induction. TRAP-positive multinucleated cells were quantified. For the release from force experiment, osteoclastogenesis was induced by 0.6 g/cm2 mechanical stimuli for 0, 1, 2, 3 or 4 days. Cell viability, TRAP-positive multinucleated cells, DCSTAMP and Cathepsin K (CTSK) gene expression were evaluated 4 days after release from force.

Results

Compressive force at 0.6 and 0.9 g/cm2 significantly increase the number of TRAP-positive multinucleated cells (P < 0.05). Release from continuous mechanical compression after 4 days significantly elevated the number of TRAP-positive multinucleated cells and DCSTAMP and CTSK mRNA expression, with no adverse effects on cell viability (P < 0.05).

Conclusions

Continuous stimulation with compressive force induced osteoclastogenesis in RAW 264.7 cells by enhancing DCSTAMP and CTSK expression, which provides new understanding of bone remodeling during orthodontic treatment.

Evaluation´ of mandibular alveolar bone in patients with different vertical facial patterns : A cross-sectional CBCT study

PURPOSE

The study aimed to investigate the morphological and structural differences of mandibular alveolar bone between different vertical facial patterns (VFP).

METHODS

In all, 66 CBCT scans of patients were selected for the study: 24 were designated as hyperdivergent, 25 as normodivergent, and 17 as hypodivergent. Fractal values of the interdental alveolus were measured at the incisor, canine, premolar, and molar regions. The minimum trabecular bone width (MTBW) of the alveolus, the buccal and lingual cortical bone thicknesses, and the total alveolar width (AW) at the minimum trabecular bone level were measured. One-way analysis of variance and Tukey test were used to compare the groups. The correlations between FMA (Frankfurt mandibular plane angle) and other measurements were analyzed by Pearson analysis.

RESULTS

No significant differences were detected in fractal values and buccal and lingual cortical bone thicknesses between the groups. The MTBW and AW of the hypodivergent individuals were found to be higher in the anterior and premolar interdental sites. FMA was found to be significantly correlated with MTBW and AW.

CONCLUSIONS

The patients with different VFPs did not exhibit significant differences in the trabecular complexity of the mandibular alveolus. Hypodivergent patients tend to have thicker trabecular and alveolar bone widths than normodivergent and hyperdivergent individuals.

Diagnostic Accuracy of Cone Beam Computed Tomography and Periapical Radiography for Detecting Apical Root Resorption in Retention Phase of Orthodontic Patients: A Cross-Sectional Study

Objectives: This clinical study aimed to evaluate and compare the diagnostic accuracy of intraoral periapical radiography (PR) and cone beam computed tomography (CBCT) in detecting external apical root resorption (EARR) in orthodontic patients during the retention phase. Methods: The research involved 41 Caucasian patients who had undergone comprehensive orthodontic treatment, with a total of 328 teeth analyzed. The Kappa values for inter- and intra-examiner agreement were high for both PR and CBCT, indicating a robust level of agreement among examiners. The study used a four-point scale for classifying EARR. Results: This study showed comparable accuracy, sensitivity, and specificity between PR and CBCT when using the most stringent criterion of "Definitely present". The data suggested that CBCT outperformed PR when using a less stringent criterion ("Definitely present" or "Probably present"), particularly for maxillary incisors. However, overall diagnostic performance, as measured by the area under the ROC curve, showed only a slight advantage for CBCT over PR. Areas under the ROC curve range between 0.85 and 0.90 for PR and between 0.89 and 0.92 for CBCT. According to DeLong's test, there is no evidence to conclude that the area under the ROC curve is different for PR and CBCT. Conclusions: Both PR and CBCT are accurate diagnostic tools for identifying EARR, with PR being deemed more suitable for routine clinical use due to its cost-effectiveness and lower radiation exposure. The findings emphasize the importance of considering the risk-benefit ratio when deciding on imaging modalities for monitoring EARR in orthodontic patients.

Orthodontic Risk Perspectives among Orthodontists during Treatment: A Descriptive Pilot Study in Greece and Slovakia

This study explores orthodontists' perspectives on risks associated with orthodontic treatment, as described by Greek and Slovak orthodontists. Informed by the foundational importance of effective communication of risk perspectives in health sciences, particularly in facilitating valid consent and shared decision-making, this research addresses gaps identified in the literature concerning the consistent communication of potential treatment risks based on demographic and cultural characteristics. This study identifies 15 potential critical risks during orthodontic treatment. These risks include root resorption; temporary undesired changes to the occlusion; sleep difficulties; not achieving an ideal result; development of black triangles between teeth; taking additional X-rays; speech difficulties; using a protective splint during sports; duration of treatment; number of visits; transmission of infectious diseases; and swallowing orthodontic appliances. A questionnaire, distributed electronically to orthodontists in Greece (N1 = 570) and Slovakia (N2 = 210) from September 2022 to December 2022, aimed to assess risk communication practices, taking into consideration socio-demographic factors, such as country, gender, age, and academic-degree-related variations. A total of 168 valid questionnaires (91 from Slovakia and 77 from Greece) were obtained, indicating significant disparities in the risks emphasized and preferred forms of consent. The Greek orthodontists focused more on the risks involved, such as relapse, root resorption, temporal occlusal changes, and failure of desired movement, while the Slovak practitioners tended to be more interested in sleeping difficulties, temporal occlusal changes, and not achieving an ideal result. They also obtained written or digital consent from patients or their parents/guardians more frequently than the Greek team. Male orthodontists discussed specific risks more frequently, including relapse and extractions, whereas females preferred written or digital consent. PhD-trained orthodontists prioritized certain risks, indicating the need for tailored approaches. This study underscores the dynamic nature of risk assessment in orthodontic practice, emphasizing its ethical and strategic dimensions. The findings advocate for tailored risk communication strategies that recognize individual, contextual, and cultural factors, and the need for an orthodontic informed consent protocol for a tailored communication approach for patients to elevate the standard of care in European orthodontics. The reliance on digital tools reflects contemporary trends in enhancing patient understanding, thereby supporting ongoing innovation in orthodontic practices.

Biomechanical Simulation of Orthodontic En-Bloc Retraction Comparing Compound Technique and Sliding Mechanics Using a HOSEA Robotic Device

En-bloc retraction is a common procedure in orthodontic therapy. The application of palatal root torque moments is required to control incisor inclination during retraction, yet studies comparing forces and moments with respect to different mechanics are lacking. This study aimed to investigate the forces and moments during orthodontic en-bloc retraction using a robotic biomechanical simulation system, comparing two distinct approaches: (I) compound technique [stainless steel (SS) combined with nickel-titanium (NiTi)] using industrially pretorqued retraction-torque-archwires (RTA) in combination with NiTi closed coil springs; (II) conventional sliding mechanics using SS archwires with manually applied anterior twist bends in combination with elastic chains. Two dimensions (0.017" × 0.025" and 0.018" × 0.025") and ten archwires per group were investigated using 0.022" slot self-ligating brackets. Kruskal-Wallis tests with a significance level of α = 0.05 were conducted. The biomechanical simulation showed that en-bloc retraction was characterized by a series of tipping and uprighting movements, differing significantly regarding the examined mechanics. Collateral forces and moments occurred in all groups. Notably, RTA exhibited fewer extrusive forces. The most bodily movement was achieved with the compound technique and the 0.018" × 0.025" RTA. Sliding mechanics exhibited maximum palatal root torque moments of more than 20 Nmm, exceeding recommended values.