Evaluation of root resorption following orthodontic intrusion: a systematic review and meta-analysis

Impact of fixed appliance treatment on root resorption in root canal-treated teeth: a systematic review and meta-analysis

OBJECTIVE

The relationship between orthodontic treatment and root resorption in endodontically treated teeth remains controversial. This systematic review and meta-analysis aimed to evaluate the effects of fixed appliance treatment on root resorption in root canal-treated teeth compared to vital teeth.

METHODS

A comprehensive literature search was conducted across multiple databases including PubMed, Embase, Cochrane Library, Web of Science, Sinomed, CNKI, and Wanfang. Studies comparing root resorption between root canal-treated teeth and vital teeth during orthodontic treatment were included. The methodological quality was assessed using the Cochrane risk of bias tool. Standardized mean differences (SMD) with 95% confidence intervals (CI) were calculated using random-effects models.

RESULTS

Ten studies involving 266 patients met the inclusion criteria. The overall effect showed no significant difference in root resorption between root canal-treated teeth and vital teeth (SMD = -0.08, 95% CI: -0.24 to 0.08, I² = 7.0%). Subgroup analyses revealed no significant differences based on measurement methods, extraction versus non-extraction treatment, or tooth position. However, extraction cases demonstrated a numerical trend toward greater root resorption in root canal-treated teeth (SMD = -0.70, 95% CI: -1.50 to 0.11, I² = 67.1%, p = 0.048), while the non-extraction group showed no meaningful differences (SMD = -0.07, 95% CI: -0.42 to 0.28, I² = 49.2%, p = 0.096).

CONCLUSIONS

This meta-analysis suggests that root canal-treated teeth do not show significantly different root resorption patterns compared to vital teeth during orthodontic treatment. However, extraction cases may require careful monitoring due to a tendency toward increased root resorption.

Orthodontically induced root resorption in endodontically treated and vital teeth: a cone beam computer tomographic study

BACKGROUND

Orthodontically induced root resorption (OIRR) is a common side effect of orthodontic treatment. This study compares the degree of OIRR between root-filled teeth (RFT) and vital pulp teeth (VPT), and analyzes relevant study variables.

METHODS

We conducted a retrospective study on 69 patients who had undergone orthodontic treatment. Using Cone-beam computed tomography (CBCT), we measured changes of root length before and after treatment through a unique method involving three-dimensional (3D) image registration and superimposition. Factors related to the OIRR such as gender, type of treatment, tooth type, age, duration of treatment and distance of root movement were considered.

RESULTS

The sample included 55 females and 14 males aged 27.19 ± 6.08 years. On the basis that there was no significant difference in the root movement distance between RFT and VPT, RFT showed significantly less OIRR than VPT (P < 0.05). Gender did not significantly impact on OIRR for either RFT or VPT group (P > 0.05). In women specifically, RFT displayed less resorption than VPT (P < 0.05). For treatment type, extraction cases demonstrated a lower degree of OIRR in RFT than VPT (P < 0.05), and notable greater OIRR in with-extraction group compared to no-extractions group was found in RFT (P < 0.05), but not in VPT (P > 0.05). Tooth type did not yield significant differences in OIRR overall; however, upper teeth and premolars experienced lower resorption in RFT than in VPT (P < 0.05). Cases treated with fixed appliance had higher OIRR in both RFT and VPT than those with clear aligners (P < 0.05). Age did not correlate significantly with OIRR for either group (P > 0.05). And duration of treatment positively correlated with OIRR for both types (RFT: r = 0.5506, P < 0.0001; VPT: r = 0.4371, P = 0.0002), so did root movement distance (RFT: r = 0.2955, P = 0.0140; VPT: r = 0.2790, P = 0.0206).

CONCLUSIONS

RFT exhibit significantly less OIRR than VPT after orthodontic treatment. Treatment type, appliance type, duration of treatment and root movement distance are significant factors influencing OIRR. Personalized orthodontic treatment plans and vigilant monitoring are crucial to mitigate OIRR risks.

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.

Combined anterior and posterior miniscrews increase apical root resorption of maxillary incisors in protrusion and premolar extraction cases

Objective

Miniscrews are commonly utilized as temporary anchorage devices (TADs) in cases of maxillary protrusion and premolar extraction. This study aimed to investigate the effects and potential side effects of two conventional miniscrew configurations on the maxillary incisors.

Methods

Eighty-two adult patients with maxillary dentoalveolar protrusion who had undergone bilateral first premolar extraction were retrospectively divided into three groups: non-TAD, two posterior miniscrews only (P-TADs), and two anterior and two posterior miniscrews combined (AP-TADs). Cone-beam computed tomography was used to evaluate the maxillary central incisors (U1).

Results

The AP-TADs group had significantly greater U1 intrusion (1.99 ± 2.37 mm, n = 50) and less retroclination (1.70° ± 8.80°) compared to the P-TADs (-0.07 ± 1.65 mm and 9.45° ± 10.68°, n = 60) and non-TAD group (0.30 ± 1.61 mm and 1.91° ± 9.39°, n = 54). However, the AP-TADs group suffered from significantly greater apical root resorption (ARR) of U1 (2.69 ± 1.38 mm) than the P-TADs (1.63 ± 1.46 mm) and non-TAD group (0.89 ± 0.97 mm). Notably, the incidence of grade IV ARR was 16.6% in the AP-TADs group, significantly higher than the rates observed in the P-TADs (6.7%) and non-TAD (1.9%) groups. Multiple regression analysis revealed that after excluding tooth movement factors, the AP-TADs configuration resulted in an additional 0.5 mm of ARR compared with the P-TADs group.

Conclusions

In cases of maxillary protrusion and premolar extraction, the use of combined anterior and posterior miniscrews enhances incisor intrusion and minimizes torque loss of the maxillary incisors. However, this approach results in more severe ARR, likely due to the increased apical movement and composite force exerted.

Experts consensus on management of tooth luxation and avulsion

Traumatic dental injuries (TDIs) of teeth occur frequently in children and adolescents. TDIs that impact the periodontal tissues and alveolar tissue can be classified into concussion, subluxation, extrusive luxation, intrusive luxation, lateral luxation, and avulsion. In these TDIs, management of injured soft tissue, mainly periodontal ligament, and dental pulp, is crucial in maintaining the function and longevity of the injured teeth. Factors that need to be considered for management in laxation injuries include the maturation stage of the traumatic teeth, mobility, direction of displacement, distance of displacement, and whether there are alveolar fractures. In avulsion, the maturation stage of the permanent tooth, the out-socket time, storage media/condition of the avulsed tooth, and management of the PDL should also be considered. Especially, in this review, we have subdivided the immature tooth into the adolescent tooth (Nolla stage 9) and the very young tooth (Nolla stage 8 and below). This consensus paper aimed to discuss the impacts of those factors on the trauma management and prognosis of TDI to provide a streamlined guide for clinicians from clinical evaluation, diagnostic process, management plan decision, follow-up, and orthodontic treatment for tooth luxation and avulsion injuries.

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.

Three-dimensional volumetric evaluation of root resorption in maxillary anteriors following en-masse retraction with varying force vectors - a randomized control trial

BACKGROUND

Root resorption in orthodontics is associated with direction and magnitude of force application as primary etiological factors. Well-controlled trials that utilize three-dimensional segmentation to detect volumetric changes in tooth structure are required to assess the quantitative nature of root resorption.

OBJECTIVE

To assess the severity of root resorption (RR) during retraction of maxillary anteriors with three different force vectors (with and without skeletal anchorage) via cone-beam computed tomography (CBCT) superimpositions.

TRIAL DESIGN

Three-arm parallel randomized clinical trial (RCT).

MATERIALS AND METHODS

Forty-two (16 males, 26 females) patients, (17-28 years), in permanent dentition with bimaxillary protrusion were randomly allocated to three groups of 14 patients each using block randomization (1:1:1 ratio) and allocation concealment. En-masse anterior retraction post first premolar extractions was carried out with modified force vectors in the three groups based on anchorage type [Molar, Mini-implant and Infrazygomatic crest (IZC) bone screws]. Volumetric root loss and linear dimensional changes were blindly assessed on initial (T0) and final (T1, end of space closure) CBCT scans. Normality distribution of values was done using Shapiro-Wilk's test. ANOVA and Post-hoc Tukey HSD test were done to compare measurements between groups at significance levels (P < .05).

RESULTS

Forty patients were analysed (14, 14, and 12 in three groups). Significant volumetric loss was noted in all groups. Central incisors demonstrated a significant reduction in IZC group (81.5 ± 21.1 mm3 ) compared to conventional (50.1 ± 26.5 mm3 ) and mini-implant groups (76.1 ± 27.6 mm3 ). Canines demonstrated a significant reduction in mini-implant group (108.9 ± 33.9 mm3 ) compared to conventional (68.8 ± 42.5 mm3 ) and IZC groups (103.1 ± 29.1 mm3 ). Regarding linear parameters, central incisors and canines revealed significant root length reduction in both skeletal anchorage groups. Lateral incisors showed no significant changes between groups.

CONCLUSIONS

Intrusive force vectors generated during skeletally anchored retraction can predispose anteriors to an increased risk of resorption. Greater loss of root volume was noted in the centrals and canines when retracted with skeletal anchorage.

LIMITATIONS

Small sample size and variations during CBCT acquisition.

HARMS

Low-dose CBCT scans were taken at T0 and T1 treatment intervals.

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.

Assessment of the efficacy of various maxillary molar intrusion therapies: a systematic review

AIMS

To systematically assess the efficacy of the various interventions used to intrude maxillary molars. Furthermore, to evaluate associated root resorption, stability of intrusion, subsequent vertical movement of mandibular molars, cost effectiveness, compliance, patient reported outcomes and adverse events.

METHODS

A pre-registered and comprehensive literature search of published and unpublished trials until March 22nd 2023 with no language restriction applied in PubMed/Medline, Embase, Scopus, DOSS, CENTRAL, CINAHL Plus with Full Text, Web of Science, Global Index Medicus, Dissertation and Theses Global, ClinicalTrials.gov, and Trip (PROSPERO: CRD42022310562). Randomized controlled trials involving a comparative assessment of treatment modalities used to intrude maxillary molars were included. Pre-piloted data extraction forms were used. The Cochrane Risk of Bias tool was used for risk of bias assessment, and The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system was used for certainty of evidence appraisal.

RESULTS

A total of 3986 records were identified through the electronic data search, of which 24 reports were sought for retrieval. Of these, 7 trials were included. One trial was judged at high risk of bias, while the others had some concerns. Based on individual small sample studies, maxillary molar intrusion was achieved using temporary anchorage devices (TADs) and rapid molar intruder appliance (RMI). It was also observed to a lesser extent with the use of open bite bionator (OBB) and posterior bite blocks. The molar intruder appliance and the posterior bite blocks (spring-loaded or magnetic) also intruded the lower molars. Root resorption was reported in two studies involving TADs. None of the identified studies involved a comparison of conventional and TAD-based treatments for intrusion of molars. No studies reported outcomes concerning stability, cost-effectiveness, compliance and patient-reported outcomes. Insufficient homogeneity between the included trials precluded quantitative synthesis. The level of evidence was very low.

CONCLUSIONS

Maxillary molar intrusion can be attained with different appliances (removable and fixed) and with the use of temporary anchorage devices. Posterior bite blocks (spring-loaded or magnetic) and the RMI offer the additional advantage of intruding the mandibular molars. However, stability of the achieved maxillary molar intrusion long term is unclear. Further high-quality randomized controlled trials are needed.

Root resorption during maxillary molar intrusion with clear aligners: a randomized controlled trial

OBJECTIVES

To compare changes in maxillary molar root resorption, intrusion amount, dentoskeletal measures, and maximum bite force (MBF) between clear aligners (CA) and fixed appliances with miniscrew (FM) during molar intrusion.

MATERIALS AND METHODS

Forty adults with anterior open bite were randomized into either CA or FM groups. Lateral cephalograms, cone-beam computed tomography (CBCT), and MBF were collected at pretreatment (T0) and 6 months of treatment (T1). Maxillary molar intrusion in FM were intruded by nickel-titanium (NiTi) closed-coil spring delivered force (150 grams/side) while clear aligners combined with squeezing exercise were performed in CA. Parametric tests were used for statistical analysis.

RESULTS

After 6 months of treatment, significant root resorption of 0.21-0.24 mm in CA and 0.38-0.47 mm in FM were found while maxillary molars were intruded 0.68 and 1.49 mm in CA and FM, respectively. CA showed significant less root resorption and intrusion than FM. Overbite, bite closing, and MBF increased significantly. CA showed significantly less overbite and SN-MP changes but more MBF increase than FM. MBF in CA was correlated with the amount of maxillary molar intrusion (r = 0.736, P < .05).

CONCLUSIONS

Maxillary molar intrusion and root resorption in CA were half the amount in FM in 6 months. The amount of maxillary molar root resorption was one-third of the intrusion distance. CA displayed less overbite increase and bite closing but more MBF increase than FM. MBF in CA was positively correlated with the molar intrusion amount.

Evaluation of root position during orthodontic treatment via multiple intraoral scans with automated registration technology

INTRODUCTION

This study aimed to introduce a method for dynamically monitoring root position with intraoral scans using automated crown registration and root segmentation with artificial intelligence technology and to evaluate its accuracy using a novel semiautomatic root apical distance measurement procedure.

METHODS

The sample consisted of 412 teeth from 16 patients whose intraoral scans and cone-beam computed tomography (CBCT) were obtained before and after treatment. Crowns from intraoral scans and roots segmented from CBCT with artificial intelligence technology before treatment were registered, integrated, and divided into individual teeth. With an automated registration program, the virtual root was constructed by crown registration before and after treatment. The distance deviation of the root position at the apex between the virtual root and the actual root, which served as a control, was measured and decomposed into the distance deviation in the mesiodistal and buccolingual directions.

RESULTS

The shell deviation of crown registration between CBCT and oral scan before treatment was 0.19 ± 0.04 mm and 0.22 ± 0.04 mm in the maxilla and mandible, respectively. The apical root position distance deviations were 0.27 ± 0.12 mm in the maxilla and 0.31 ± 0.11 mm in the mandible. There was no significant difference between root position in mesiodistal and buccolingual directions.

CONCLUSIONS

Applying automated crown registration and root segmentation with artificial intelligence technology in this study improved the accuracy and efficiency of monitoring root position. In addition, the innovative semiautomatic distance measurement procedure can more precisely distinguish the root position discrepancy.

Orthodontically induced external apical root resorption considerations of root-filled teeth vs vital pulp teeth: a systematic review and meta-analysis

INTRODUCTION

The purpose of this systematic review was to research the difference between root-filled teeth (RFT) and vital pulp teeth (VPT) in orthodontically induced external apical root resorption (EARR) and to offer suggestions for clinicians on therapeutic sequence and timing when considering combined treatment of endodontic and orthodontic.

MATERIALS AND METHODS

An electronic search of published studies was conducted before November 2022 in PubMed, Web of Science and other databases. Eligibility criteria were based on the Population, Intervention, Comparison, Outcome, and Study design (PICOS) framework. RevMan 5.3 software was used for statistical analysis. Single-factor meta-regression analysis was used to explore the sources of literature heterogeneity, and a random effects model was used for analysis.

RESULTS

This meta-analysis comprised 8 studies with 10 sets of data. As there was significant heterogeneity among the studies, we employed a random effects model. The funnel plot of the random effects model exhibited a symmetrical distribution, indicating no publication bias among the included studies. The EARR rate of RFT was significantly lower than that of VPT.

CONCLUSIONS

In the context of concurrent endodontic and orthodontic treatment, priority should be given to endodontic therapy, as it serves as the foundation for subsequent orthodontic procedures. The optimal timing for orthodontic tooth movement post-root canal therapy is contingent upon factors such as the extent of periapical lesion resolution and the degree of dental trauma sustained. A comprehensive clinical assessment is essential in guiding the selection of the most suitable approach for achieving optimal treatment outcomes.

Efficacy of lower arch leveling, lower incisors' root resorption, and pain associated with the correction of curve of Spee using different orthodontic archwires: a randomized clinical trial

OBJECTIVES

To compare between 3 archwires (AWs) for leveling curve of Spee (COS) in terms of efficacy of reduction, external apical root resorption (EARR), pain experienced, and the lower arch dimensional changes during COS leveling.

TRIAL DESIGN

Randomized clinical trial.

SETTING

Jordan University of Science and Technology Postgraduate dental clinics.

MATERIAL AND METHODS

Fifty-three subjects with COS > 5 mm were included in this study. The subjects were randomly divided into three groups based on the AW used: group 1, 0.017 × 0.025-inch stainless-steel (SS) AW; group 2, 0.019 × 0.025-inch SS AW; and group 3, 0.021 × 0.025-inch β-titanium (TMA) AW. The intervention was randomly allocated using the permuted random block size of 3 with a 1:1:1 allocation ratio. In the three groups, a 5-mm depth reverse COS was placed in the AWs. The following time points were defined for COS assessment: T1, before interventional leveling AW placement; and T2-T7, 1-6 months after interventional leveling AW placement. Records consisted of dental study models and periapical (PA) radiographs. Pain scores were recorded using visual analogue scale. Patients were followed up on a monthly basis until COS < 1.5 mm.

MAIN OUTCOME MEASURES

COS depth reduction, lower incisors' EARR, pain scores, and arch dimensional changes.

RESULTS

An overall reduction of 3.82 mm, 4.47 mm, and 3.85 mm of the depth of COS was achieved in groups 1, 2, and 3, respectively. The mean differences of 0.65 mm between groups 1 and 2 and 0.62 mm between groups 2 and 3 were significant at P < 0.05. Lower incisors' EARR during leveling COS ranged from 0.68 to 0.72 mm, from 0.63 to 0.82 mm, and from 0.53 to 0.88 mm in groups 1, 2, and 3, respectively (P > 0.05). Higher pain scores were reported by group 2 subjects during the first 24 h. Arch length and width increased significantly in groups 2 and 3 (P < 0.05). In all groups, COS leveling was achieved by lower incisor intrusion and proclination and lower molar extrusion.

CONCLUSIONS

All investigated AWs were effective in leveling COS with minimal lower incisors' EARR (< 1 mm). COS was leveled by lower incisors' intrusion and proclination and lower molar extrusion. Pain scores were the highest in group 2 during the first 24 h.

CLINICAL RELEVANCE

The 3 investigated leveling AWs were effective for the leveling COS and at the same time safe on the roots of the lower anterior teeth.

Dynamics, Efficacies, and Adverse Effects of Maxillary Full-Arch Intrusion Using Temporary Anchorage Devices (Miniscrews): A Finite Element Analysis

Introduction

Absolute anchorages obtained from temporary anchorage devices (TADs, miniscrews) considerably facilitate dental movements and make some very difficult movements such as full-arch intrusions possible. Despite the significance of assessing strategies to fully intrude the arch using mini-implants, there is no study in this regard except a few case reports. Therefore, we simulated/tested 4 scenarios.

Methods

Four maxilla models were created with different miniscrews/appliances: (1) two miniscrews were placed distal to laterals and one in the mid sagittal region. (2) Two mini-implants were inserted in mesial of canines and 2 others between bilateral first and second molars, plus another TAD in the midpalatal area, plus a transpalatal arch (TPA). (3) Two mini-implants were inserted between bilateral canines and first premolars and 2 others between bilateral first and second molars + TPA. (4) Two mini-implants were installed between lateral-and-canine and 2 miniscrews between second premolars and first molars + TPA. Intrusive forces (80 g anterior, 150 g posterior) were exerted using stainless-steel coil springs. Stresses/displacements were measured. Risk of external root resorption was evaluated.

Results

The highest amounts of incisor/molar intrusion were seen in model 1. Model 2 had fewer intrusions, but its control over undesired movements was greater. Model 4 drastically reduced molar intrusion and considerably increased premolar intrusion. Overall amounts of intrusion were highest in the first 2 models, marking them as proper candidates for cases needing greater intrusion extents. Model 2 may be useful when miniscrew loosening/failure is a concern, while model 1 is recommended when fewer miniscrews are allowed. Overall, the highest and lowest root resorptions might occur in models 1 and 4, respectively.

Conclusions

Each model showed certain efficacies/drawbacks and thus is recommended for a particular set of cases. Therefore, depending on the diagnosis and treatment plan, one or more of these scenarios might be desirable.

The Effect of Vitamin D3 on the Alignment of Mandibular Anterior Teeth: A Randomized Controlled Clinical Trial

Objectives

To investigate the effect of vitamin D₃ level on the alignment of mandibular anterior teeth in adults and explore the associated root resorption and pain perception. Trial Design. Multicentre, double blinded randomized clinical trial. Subjects and Methods. Adult patients aged 18–30 years, with moderate mandibular incisor crowding [Little's Irregularity index (LII) 3–6 mm], needing nonextraction treatment with fixed orthodontic appliance, were randomly allocated into two groups with 1 : 1 allocation ratio. In the 1^st group (normal vitamin D₃ level group [ND₃G]), vitamin D level was measured and corrected to normal before starting orthodontic treatment, while in the 2^nd group [control group (CG)] the vitamin D level was kept unknown until completion of the alignment phase. Outcome measures included mandibular incisor crowding using LII, orthodontically induced root resorption (OIRR), and pain perception. Independent sample t-test was used to compare the duration of treatment, the effectiveness of alignment, and OIRR between groups, while differences in pain perception were analysed by Mann–Whitney U-test (P < 0.05).

Results

Out of 87 patients recruited from four centres, 33 patients were randomly allocated into two groups (17 patients to ND₃G and 16 patients to CG). Time elapsed for the complete alignment of the mandibular incisor crowding was one month shorter in ND₃G (23.532% faster), and the improvement percentage was significantly higher in all periods when compared to the CG. The amount of OIRR was not significantly different between groups; however, pain during the first three days of alignment was significantly less in ND₃G.

Conclusions

Having optimal vitamin D₃ level reduced the alignment time and pain associated with orthodontic treatment, but it had no role in reducing OIRR. Registration. The trial was registered with ClinicalTrials.gov on 12^th April 2021 (registration number: NCT04837781).

Root resorption associated with maxillary buccal segment intrusion using variable force magnitudes

OBJECTIVES

To compare the root resorption resulting from miniscrew-supported maxillary posterior dentoalveolar intrusion using two different force magnitudes.

MATERIALS AND METHODS

Adult patients with skeletal open bite, indicated for maxillary posterior dentoalveolar intrusion, were recruited and randomly assigned to the comparison or intervention groups. The comparison group involved applying 200 g of intrusive force per segment, which measured 20 g per root, while this force was 400 g per segment in the intervention group, measuring 40 g per root.

RESULTS

Twenty participants were included in the final analysis after 2 patients dropped out, 1 in each group, to end up with 10 subjects (200 roots) per group. There was statistically significant root resorption of 0.84 ± 0.96 mm and 0.93 ± 1.00 mm in the comparison and the intervention groups, respectively. However, there was no statistically significant difference between the groups.

CONCLUSIONS

Root resorption inevitably took place in association with orthodontic intrusion. However, increasing the magnitude of the intrusive force did not increase the amount of root resorption, either statistically or clinically.

A Potential Role of Semaphorin 3A during Orthodontic Tooth Movement

BACKGROUND

Induced tooth movement during orthodontic therapy requires mechano-induced bone remodeling. Besides various cytokines and growth-factors, neuronal guidance molecules gained attention for their roles in bone homeostasis and thus, potential roles during tooth movement. Several neuronal guidance molecules have been implicated in the regulation of bone remodeling. Amongst them, Semaphorin 3A is particular interesting as it concurrently induces osteoblast differentiation and disturbs osteoclast differentiation.

METHODS

Mechano-regulation of Sema3A and its receptors PlexinA1 and Neuropilin (RT-qPCR, WB) was evaluated by applying compressive and tension forces to primary human periodontal fibroblasts (hPDLF) and alveolar bone osteoblasts (hOB). The association of the transcription factor Osterix (SP7) and SEMA3A was studied by RT-qPCR. Mechanisms involved in SEMA3A-mediated osteoblast differentiation were assessed by Rac1GTPase pull-downs, β-catenin expression analyses (RT-qPCR) and nuclear translocation assays (IF). Osteogenic markers were analyzed by RT-qPCR.

RESULTS

SEMA3A, PLXNA1 and NRP1 were differentially regulated by tension or compressive forces in hPDLF. Osterix (SP7) displayed the same pattern of regulation. Recombinant Sema3A induced the activation of Rac1GTPase, the nuclear translocation of β-catenin and the expression of osteogenic marker genes.

CONCLUSION

Sema3A, its receptors and Osterix are regulated by mechanical forces in hPDLF. SEMA3A upregulation was associated with Osterix (SP7) modulation. Sema3A-enhanced osteogenic marker gene expression in hOB might be dependent on a pathway involving Rac1GTPase and β-catenin. Thus, Semaphorin 3A might contribute to bone remodeling during induced tooth movement.