Orthodontic Tooth Movement Research Articles

Evaluation of Alveolar Bones in the Context of Orthodontic Single-Tooth Space Closure: A Retrospective Cone Beam Computed Tomography-Based Analysis

In the literature, there are no studies evaluating alveolar bone width in areas with a single missing tooth in terms of orthodontic tooth movement. This study was meant to determine whether residual alveolar bone width in edentulous crests is a risk factor for orthodontic tooth movement. The aim of this study was to evaluate the change in the residual alveolar bone width in the edentulous region compared to the alveolar bone width on the symmetrical toothed side using CBCT in individuals with a single missing tooth in whom orthodontic tooth movement was planned. This retrospective radiographic study was performed using CBCT images that were taken before orthodontic treatment for the evaluation of the edentulous area between January 2010 and January 2022. Individuals without any systemic disease aged 18 years or older whose edentulous area was restricted to one tooth were included in this study. Bone measurements were made on cross-sectional CBCT images. Of the 265 individuals participating in this study, 129 were male and 136 were female, with a mean age of 32.67 ± 6.50 years. The distribution of 265 edentulous regions (caused by 265 tooth extractions) was as follows: 23 were in the incisor region, 54 were in the premolar region, and 188 were in the molar region. The molar region had the highest bone width among the edentulous regions (p < 0.01). Bone widths were smaller in the edentulous crests for all regions (p < 0.01). In this study, it was determined that the bone width in the areas with a single missing tooth was insufficient, and this is a risk factor for orthodontic treatment.

Protective Effect of Bovine Milk Extracellular Vesicles on Alveolar Bone Loss.

Bovine milk extracellular vesicles (MEVs) have demonstrated therapeutic potential in regulating bone cell activity. However, the outcome of their use on alveolar bone loss has not yet been demonstrated. This study evaluates the effect of oral administration of MEVs on ovariectomized (OVX) mice. There is a reduced height of the alveolar bone crest in OVX mice by MEVs treatment, but the alveolar bone parameters are not altered. OVX mice are then submitted to a force-induced bone remodeling model by orthodontic tooth movement (OTM). MEVs-treated mice have markedly less bone remodeling movement, unlike the untreated OVX mice. Also, OVX mice treated with MEVs show an increased number of osteoblasts and osteocytes associated with higher sclerostin expression and reduce osteoclasts in the alveolar bone. Although the treatment with MEVs in OVX mice does not show differences in root structure in OTM, few odontoclasts are observed in the dental roots of OVX-treated mice. Compared to untreated mice, maxillary and systemic RANKL/OPG ratios are reduced in OVX mice treated with MEVs. Treatment with MEVs results in positive bone cell balance in the alveolar bone and dental roots, indicating its beneficial potential in treating alveolar bone loss in the nutritional context.

Effects of Hydrogen-Rich Water on Interleukin-1β, Number of Osteoclasts and Osteoblasts in Streptozotocin-induced Diabetic Rats with Orthodontic Tooth Movement

BACKGROUND: Orthodontic tooth movement (OTM) may increase the risk of treatment-related complications for some diabetes mellitus (DM) patients. Hydrogen-rich water (HRW) has been demonstrated in many studies to reduce oxidative stress and cell damage. This study aimed to examine the levels of interleukin (IL)-1β, blood glucose level, body weight, tooth displacement, and population of osteoclasts and osteoblasts in diabetic rats with OTM.METHODS: Thirty rats (Rattus novergicus) were divided into 6 groups: OTM, HRW, DM, DM+OTM, DM+HRW, and DM+OTM+HRW. DM, DM+OTM, DM+HRW, and DM+OTM+HRW groups were induced with streptozotocin (STZ) after 8 weeks of high-fat diet (HFD) and continued being fed HFD for 4 weeks. OTM, DM+OTM, and DM+OTM+HRW groups were placed on an orthodontic device for the orthodontic treatment. HRW, DM+HRW, and DM+OTM+HRW groups were administered HRW via oral gavage 3 times a day for 4 weeks. At the end of the study, all rats were euthanized and blood samples were collected for IL-1β measurement using enzyme-linked immunosorbent assay (ELISA) kits. Meanwhile, the rats’ maxilla was taken to measure tooth movement, and the number of osteoclast and osteoblast were counted.RESULTS: The highest increase of IL-1β was in the DM+OTM group (140.07±5.14 pg/mL) and the lowest was in the HRW group (92.80±2.89 pg/mL). The average number of osteoblasts were higher in tension sites, while osteoclasts were higher in pressure sites.CONCLUSION: Consumption of HRW in STZ-induced diabetic rats with OTM can reduce IL-1β levels, reduce tooth mobility, and promote bone remodeling.KEYWORDS: diabetes mellitus, hydrogen rich water, interleukin-1β, orthodontic tooth movement, osteoblast, osteoclast

Evaluation of Two Bone Anchored Appliances During En Masse Distalization of Maxillary Buccal Segment with Class II Patients; A Comparative Clinical Study

Objective: to assess quality of orthodontic tooth movement during distalization by two different skeletally anchored distalizing appliances. Patients and methods: the current study was applied on 22 orthodontic patients with class ΙΙ molar relationship. Patients were divided into two active groups; group Ι: include 11 patients treated by modified sagittal screw distalizer and group ΙΙ: include 11 patients treated by modified distal jet distalizer. Quality of distalization was assessed by the following measurements; first and second premolars root horizontal distance (mm), first and second molars root horizontal distance(mm), SNA, SNB, U1 to FH. Results: The highest change (%) in first molar root horizontal distance (mm) was recorded in group II with a decrease by -11.5 % in the left side and -11.4 % in the right side. Conclusion: Bone anchored Distal Jet and modified Sagittal screw distalizer provide an effective tool for treating mild to moderate class II malocclusion. But the modified distal jet produces high quality of distalization than the modified Sagittal screw distalizer.

Satisfaction with Duration of Orthodontic Treatment, Knowledge and Perception of Accelerated Orthodontics by Nigerian Dental Practitioners: A Questionnaire Study

Background: The duration of orthodontic treatment with its attendant complications has been a subject of concern in the specialty of orthodontics, necessitating the need to quicken the rate of orthodontic tooth movement. Despite the growing acceptance of accelerated orthodontics, there is paucity of related information from Nigeria.
 Aim: To assess the satisfaction of Nigerian dental practitioners with the duration of orthodontic treatment and their knowledge and perception of accelerated orthodontics.
 Materials and Methods: Both electronic and physical survey was conducted among Nigerian dental practitioners between January and June 2023 involving both those in Government employment and private practice. The questionnaire contained questions on satisfaction with duration of orthodontic treatment, knowledge and perception of accelerated orthodontics. The data was analysed using the IBM SPSS version 25. In addition to the descriptive statistics, the Chi-square statistics was used to test the hypotheses with the significance level set at P < .05.
 Results: The response rate was 50%. The participants gave significant differences in their levels of satisfaction with the duration of orthodontic treatment but only 42.4% of them were satisfied. Some knowledge-deficit of accelerated orthodontics was observed among the participants with significantly correct responses in only four out the seven methods assessed (P < .05), while their positive perception of accelerated orthodontics was generally significant (P < .05).
 Conclusion: The participants were not significantly satisfied with the duration of orthodontic treatment; had knowledge-deficit of the methods of accelerated orthodontics but significant positive perception.

The role ovariectomies and/or the administration of artificial female sex hormones play in orthodontic tooth movement: A systematic review.

The objective was to assess how ovariectomy or the administration of artificial female sex hormones affects orthodontic tooth movement (OTM) with fixed appliances. An electronic search of indexed databases was completed without language or time restrictions up to June 2022. The following eligibility criteria were utilized: (i) prospective original controlled clinical studies; (ii) experimental studies on animal models; (iii) subjects undergoing orthodontic therapy with fixed appliances; (iv) clearly defined control groups not undergoing ovariectomy or administration of artificial female sex hormone; and (v) studies with experimental groups receiving the intervention of interest (ovariectomy or artificial female sex hormone administration). Review articles, letters to the editor, case reports, case series, commentaries, cross-sectional studies, retrospective studies, and studies with no well-defined control group were excluded. The quality of the available evidence and the risk of bias within the studies were assessed. All disagreements were resolved via discussion. Seven animal studies were included in the systematic review. Five studies reported that ovariectomy increased the rate of orthodontic tooth movement. Two studies reported that the administration of artificial female sex hormones decreased the rate of orthodontic tooth movement. There is an association between ovariectomies and OTM and between the administration of artificial female sex hormones and OTM. The full extent of the association remains unclear due to the biases that are present and the length of time of orthodontic therapy.

Dentoalveolar anomalies and modern views on the mechanisms of local stress-modeling effect of orthodontic appliances on the periodontal tissues (a literature review)

The aim of the study was to highlight the results of modern scientific developments in tracing the mechanisms of local stress-modeling effect of orthodontic appliances on the oral cavity and periodontal tissues during the active period of orthodontic treatment. Materials and methods. The research methodology was implemented in the collection and analysis of scientific results on the stress-modeling effect of orthodontic appliances in patients with dentoalveolar anomalies obtained from the processed sources – published full-text articles of original and fundamental research by national and foreign authors based on the evidential databases MEDLINE / PubMed, PMC, Scopus, Web of Science, Cochrane, Google Scholar, ResearchGate and other scientific and practical resources. Results. The main components of the stress-modeling effect of fixed orthodontic appliances on the oral cavity, and particularly on the periodontal tissues, were analyzed. The proportion of various complications is quite high and ranges from 32.7 % to 50.0 % of all cases. The development of oxidative stress during orthodontic treatment is potentiated by microcirculatory disorders and hypoxia of the periodontal tissues. The peculiarities of the periodontal cellular complex reaction, which has the ability to bear stress generated in the actin cytoskeleton by direct mechanical stimulation, to extracellular matrix proteins, affecting the three-dimensional organization of the extracellular matrix and its remodeling, have been traced. The role of lipid peroxidation, antioxidant system and enzymatic reaction of oral and crevicular fluids was also defined. Conclusions. The development of oxidative stress during orthodontic treatment can be caused by local and systemic exposure to metals, corrosion processes in particular; by inflammation of periodontal tissues due to poor oral hygiene and activation of periodontal pathogenic microflora; by aseptic inflammation in the periodontal ligament due to the use of mechanical force. Certain enzymes of the oral fluid, in particular lactate dehydrogenase, can act as a sensitive marker of changes in the periodontal ligament metabolism during orthodontic teeth movement. The localization and nature of free radical pathology are largely caused by the nature of an exogenous inducer of lipid peroxidation and the genotypic characteristics of antioxidant system. It is this ratio that determines the initiation and further chain branching of free radical reactions. Without normalization of all pathogenetic links, successful treatment of inflammatory and dystrophic-inflammatory diseases of the periodontal tissues, in particular in orthodontic patients, is impossible.

Predictability of Dental Distalization with Clear Aligners: A Systematic Review.

The current review aims to evaluate the scientific evidence relating to the effectiveness of treatment with clear aligners (CAs) in controlling distalization orthodontic tooth movement. "Orthodontics, aligners" and "distalization" were the search terms used on the Scopus, Web of Science and Pubmed databases with the Boolean operator "AND". The results of the last ten years of research were 146 studies; of these, 19 publications were included for this review. The distalization movement is possible with invisible masks alone, but the risk of losing anchorage in the anterior sectors is very probable. The stability of the results and the reduction of unwanted effects can be guaranteed by the use of skeletal anchoring devices and interproximal enamel reduction (IPR), with which compensations are obtained to reduce the initial overjet. Temporary anchorage devices (TADs) can be used to manage posterior anchorage after distalization of maxillary molars with aligners. This hybrid approach has demonstrated the greatest orthodontic success. TADs are useful aids to provide direct and indirect skeletal anchorage. The opposite effect must be considered when planning dental distalization, especially of the molars, in patients with large overjet, and corrective measures or the use of auxiliaries may be necessary to prevent midcourse corrections. This systematic review provides a critical evidence-based assessment of the predictability of dental distalization with CAs, an ever-evolving orthodontic technique.

Orthodontic treatment in stage IV periodontitis patients: Timing, management and long-term prognosis

Patients affected by severe periodontitis can develop a secondary malocclusion due to pathologic tooth migration that, if untreated, can hinder the maintenance of the entire dentition. In these cases, the combination of the appropriate stepwise periodontal therapy together with orthodontic treatment may become essential to re-establish health, aesthetics and function, leading to patient satisfaction and long-term stability. However, to successfully perform orthodontic tooth movement in stage IV periodontitis patients is paramount to carefully plan the treatment with a interdisciplinary approach, respecting the correct timing of the different phases of treatment, adapting biomechanics and appliance design individually, considering loss of periodontal support suffered from each patient. At the end of orthodontic treatment, after eventual prosthetic procedures, life-long retention and supportive periodontal care are needed to ensure good long-term prognosis. The present review describes the diagnostic, prognostic and therapeutic challenges associated with the combined ortho-perio treatment of stage IV periodontitis patients, providing both a literature and expert-based support for a biologically-orientated approach.

MicroRNA-155 targets SOCS1 to inhibit osteoclast differentiation during orthodontic tooth movement

BackgroundMicroRNA-155 (miR-155) is a multifunctional miRNA whose expression is known to be involved in a range of physiological and pathological processes. Its association with several oral diseases has been established. However, the specific role of miR-155 in orthodontic tooth movement remains unclear. In this study, we investigated the impact of miR-155 on osteoclast differentiation and orthodontic tooth movement models, aiming to explore the underlying mechanisms.MethodsIn this experiment, we utilized various agents including miR-155 mimic, miR-155 inhibitor, as well as non-specific sequences (NC mimic & NC inhibitor) to treat murine BMMNCs. Subsequently, osteoclast induction (OC) was carried out to examine the changes in the differentiation ability of monocytes under different conditions. To assess these changes, we employed RT-PCR, Western blotting, and TRAP staining techniques. For the orthodontic tooth movement model in mice, the subjects were divided into two groups: the NaCl group (injected with saline solution) and the miR-155 inhibitor group (injected with AntagomiR-155). We observed the impact of orthodontic tooth movement using stereoscopic microscopy, micro-CT, and HE staining. Furthermore, we performed RT-PCR and Western blotting analyses on the tissues surrounding the moving teeth. Additionally, we employed TargetScan to predict potential target genes of miR-155.ResultsDuring osteoclast induction of BMMNCs, the expression of miR-155 exhibited an inverse correlation with osteoclast-related markers. Overexpression of miR-155 led to a decrease in osteoclast-related indexes, whereas underexpression of miR-155 increased those indexes. In the mouse orthodontic tooth movement model, the rate of tooth movement was enhanced following injection of the miR-155 inhibitor, leading to heightened osteoclast activity. TargetScan analysis identified SOCS1 as a target gene of miR-155.ConclusionsOur results suggest that miR-155 functions as an inhibitor of osteoclast differentiation, and it appears to regulate osteoclasts during orthodontic tooth movement. The regulatory mechanism of miR-155 in this process involves the targeting of SOCS1.

Coptisine Down-Regulates Soluble Intercellular Adhesion Molecule-1 by Inactivating Fas/FasL Signaling Pathway to Inhibit the Recurrence After Orthodontics

In this study, by constructing a rat model of orthodontic recurrence and intervening with coptisine, the IL-6, IL-8, TNF-α and soluble intercellular adhesion molecule-1 (sICAM-1) content were analyzed to assess the regulatory mechanism of coptisine on the health status of recurrent periodontal tissue after orthodontics and the occurrence of periodontal tissue inflammation. Male rats were assigned into three groups by constructing coptisine liposome nano-objects: blank group (Blank, 10 rats), orthodontic tooth movement model group (50 rats). The orthodontic tooth movement model group was randomly divided into model group (module), model control group (control-free), model coptisine treatment group (treatment-free), model blank functional liposome group (control-lip) and model functional coptisine liposome group (treatment-lip). Rats in model group were killed on the day after device was removed. Rats in other groups received equal doses of normal saline, coptisine, blank functional liposomes, and functional coptisine liposomes by intragastric administration on the day of device removal and then were killed after 7 days of continuous treatment. Through Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis, we found that Fas/FasL signaling pathway was enriched in pathways related to apoptosis, disease infection and inflammation. Western blot experiments confirmed that coptisine could inhibit Fas/FasL signaling activation in the process of relapse after orthodontics. Lipopolysaccharides (LPS) treatment significantly increased inflammatory cytokines and sICAM-1, as well as the level of Fas and FasL. Coptisine treatment inhibited LPS-induced Fas/FasL signaling pathway in periodontal ligament cells. Coptisine attenuated the relapsed inflammation after orthodontics by inhibiting Fas/FasL signaling.

Mechanisms of Osteoclastogenesis in Orthodontic Tooth Movement and Orthodontically Induced Tooth Root Resorption

Orthodontic tooth movement (OTM) is achieved by the simultaneous activation of bone resorption by osteoclasts and bone formation by osteoblasts. When orthodontic forces are applied, osteoclast-mediated bone resorption occurs in the alveolar bone on the compression side, creating space for tooth movement. Therefore, controlling osteoclastogenesis is the fundamental tenet of orthodontic treatment. Orthodontic forces are sensed by osteoblast lineage cells such as periodontal ligament (PDL) cells and osteocytes. Of several cytokines produced by these cells, the most important cytokine promoting osteoclastogenesis is the receptor activator of nuclear factor-κB ligand (RANKL), which is mainly supplied by osteoblasts. Additionally, osteocytes embedded within the bone matrix, T lymphocytes in inflammatory conditions, and PDL cells produce RANKL. Besides RANKL, inflammatory cytokines, such as interleukin-1, tumor necrosis factor-α, and prostaglandin E2 promote osteoclastogenesis under OTM. On the downside, excessive osteoclastogenesis activation triggers orthodontically-induced external root resorption (ERR) through pro-osteoclastic inflammatory cytokines. Therefore, understanding the mechanisms of osteoclastogenesis during OTM is essential in reducing the adverse effects of orthodontic treatment. Here, we review the current concepts of the mechanisms underlying osteoclastogenesis in OTM and orthodontically induced ERR.

Ten years of injectable platelet-rich fibrin.

The use of platelet-rich fibrin (PRF) has seen widespread advantages over platelet-rich plasma (PRP) in many fields of medicine. However, until 2014, PRF remained clinically available only in its solid clotted form. Modifications to centrifugation protocols and tube technology have led to the development of a liquid injectable version of PRF (i-PRF). This narrative review takes a look back at the technological developments made throughout the past decade and further elaborates on their future clinical applications. Topics covered include improvements in isolation techniques and protocols, ways to further concentrate i-PRF, and the clinical impact and relevance of cooling i-PRF. Next, various uses of i-PRF are discussed, including its use in regenerative periodontology, implantology, endodontics, temporomandibular joint injections, and orthodontic tooth movement. Furthermore, various indications in medicine are also covered, including its use in sports injuries and osteoarthritis of various joints, treatment of diabetic ulcers/wound care, and facial esthetics and hair regrowth. Finally, future applications are discussed, mainly its use as a drug delivery vehicle for small biomolecules, such as growth factors, antibiotics, exosomes, and other medications that may benefit from the controlled and gradual release of biomolecules over time.

Chroogomphus rutilus Regulates Bone Metabolism to Prevent Periodontal Bone Loss during Orthodontic Tooth Movement in Osteoporotic Rats

Chroogomphus rutilus Regulates Bone Metabolism to Prevent Periodontal Bone Loss during Orthodontic Tooth Movement in Osteoporotic Rats

LRP1-deficient leptin receptor-positive cells in periodontal ligament tissue reduce alveolar bone mass by inhibiting bone formation

ObjectiveLeptin receptor-positive (LepR+) periodontal ligament (PDL) cells play a crucial role in osteogenesis during tooth socket healing and orthodontic tooth movement; however, the factors regulating osteoblast differentiation remain unclear. This study aimed to demonstrate the function of low-density lipoprotein receptor-related protein 1 (LRP1) in alveolar bone formation by examining conditional knockout (cKO) mice lacking LRP1 in LepR+ cells. DesignBone mass and formation were examined via bone morphometric analysis. Bone formation and resorption activities were determined via histochemical staining. Additionally, PDL cells collected from molars were induced to differentiate into osteoblasts with the addition of BMP2 and to mineralize with the addition of osteogenic medium. Osteoblast differentiation of PDL cells was examined by measuring the expression of osteoblast markers. ResultsBone morphometry analysis revealed decreased mineral apposition rate and alveolar bone mass in cKO mice. Additionally, cKO mice showed a decreased number of osterix-positive cells in the PDL. cKO mice had a large number of osteoclasts around the alveolar bone near the root apex and mesial surface of the tooth. In the PDL cells from cKO mice, inhibition of mineralized matrix formation and decreased expression of alkaline phosphatase, osterix, bone sialoprotein, and osteocalcin were observed even when BMP2 was added to the medium. BMP2, BMP4, and osteoprotegerin expression also decreased, but RANKL expression increased dominantly. ConclusionLRP1 in LepR+ cells promotes bone formation by stimulating osteoblast differentiation. Our findings can contribute to clinical research on bone diseases and help elucidate bone metabolism in the periodontal tissue.

The Role of Periodontal Ligament Remodeling on Orthodontic Tooth Movement

The periodontal ligament is a connective tissue located between the cementum that covers the roots of the tooth and alveolar bone, which is composed of large amounts of fibers, cells, and blood vessels. Orthodontic tooth movements are obtained through periodontal ligament remodeling and alveolar bone in response to orthodontic forces. When the orthodontic force is applied to the teeth, an injury will occur in the periodontal ligament, and the pressure and tension side in the periodontal ligament is formed. Furthermore, vasoconstriction occurs in blood vessels and hypoxia in the periodontal ligament, triggering inflammation, angiogenesis, cell proliferation, degradation, and synthesis of extracellular matrix, bone resorption, and alveolar bone deposition. The purpose of this article is to study the mechanism of periodontal ligament remodeling on orthodontic tooth movement to obtain optimal tooth movements.

Pain Perception to Orthodontic Tooth Movement during Menstrual Cycle: A Clinical Study

Pain during orthodontic treatment is inevitable side effect. Therefore, it is the responsibility of the orthodontist to alleviate this pain as possible. Menstrual cycle is often a painful event to female. Female is the most of orthodontic patient. Hence, study the pain perception of female to orthodontic treatment during menstrual cycle is essential. Aim: the aim of the present study is to asses, if there is change in pain perception to orthodontic tooth movement during menstrual cycle. Seventeen healthy female with regular menstrual cycle intended to receive orthodontic treatment with fixed appliances were participated in the study. Elastomeric separators were placed mesial and distal to maxillary and mandibular first molars during the menstrual and postmenstrual period respectively. Visual analog scale (VAS) was used to assess pain perception at 4 hours, 24 hours, 2nd, 3rd, 4th and 5th days after the separators were placed. Data of VAS scores were statistically analyzed. There were statistically significant increase in the pain perception level after the insertion of separators during menstrual cycle period and decrease during postmenstrual period. During menstrual cycle, female experienced higher pain perception to orthodontic tooth movement. Hence, it is better to postpone orthodontic visits for female patients to postmenstrual period.

Designing of customized devices in orthodontics by digital imaging and CAD/FEM modeling

In current decade, patient’s demand of minimal orthodontic treatment have encouraged the introduction of appliance that will be lighter, improved profile and better esthetics with regard to conventional orthodontic treatment. Considering aesthetic treatment options, removable clear aligner treatment got popular among patients since it allows clinician to deliver comprehensive orthodontic treatment while maintaining comfort of patient. The aligners should exert an adequate force in order to shift the tooth to a desirable position. But, in recent times, the relation of applied force and aligner property (eg. thickness) is inadequately witnessed. This article focuses on a patient-focused framework has been formulated which depicts orthodontic movement of teeth with the help of aligners. Particularly, a finite element model is being formulated which optimizes the thickness of these aligners with respect to amount of force and moment system applied to a lower central incisor while tipping it bucco-lingually.

Periodontal ligament and alveolar bone remodeling during long orthodontic tooth movement analyzed by a novel user-independent 3D-methodology

The structural process of bone and periodontal ligament (PDL) remodeling during long-term orthodontic tooth movement (OTM) has not been satisfactorily described yet. Although the mechanism of bone changes in the directly affected alveolar bone has been deeply investigated, detailed knowledge about specific mechanism of PDL remodeling and its interaction with alveolar bone during OTM is missing. This work aims to provide an accurate and user-independent analysis of the alveolar bone and PDL remodeling following a prolonged OTM treatment in mice. Orthodontic forces were applied using a Ni–Ti coil-spring in a split-mouth mice model. After 5 weeks both sides of maxillae were scanned by high-resolution micro-CT. Following a precise tooth movement estimation, an extensive 3D analysis of the alveolar bone adjacent to the first molar were performed to estimate the morphological and compositional parameters. Additionally, changes of PDL were characterized by using a novel 3D model approach. Bone loss and thinning, higher connectivity as well as lower bone mineral density were found in both studied regions. Also, a non-uniformly widened PDL with increased thickness was observed. The extended and novel methodology in this study provides a comprehensive insight about the alveolar bone and PDL remodeling process after a long-duration OTM.

LncRNA ADAMTS9-AS2 regulates periodontal ligament cell migration under mechanical compression via ADAMTS9/fibronectin.

Periodontal ligament cells (PDLCs) are key mechanosensory cells involved in extracellular matrix (ECM) remodeling during orthodontic tooth movement (OTM). Mechanical force changes the ECM components, such as collagens and matrix metalloproteinases. However, the associations between the changes in ECM molecules and cellular dynamics during OTM remain largely uncharacterized. To investigate the influence of mechanical force on the morphology and migration of PDLCs and explore the interaction between ECM remodeling and cellular dynamics, including the detailed mechanisms involved. Human PDLCs (hPDLCs) were subjected to a static mechanical compression to mimic the compression state of OTM invitro. A mouse OTM model was used to mimic the OTM procedure invivo. The migration of hPDLCs was compared by wound healing and transwell migration assays. Moreover, expression levels of ADAM metallopeptidase with thrombospondin type 1 motif 9 (ADAMTS9) and fibronectin (FN) in hPDLCs were determined via western blotting, immunofluorescence staining, and enzyme-linked immunosorbent assays. Expression levels of ADAMTS9 and FN in mice were assessed via immunohistochemical staining. Additionally, the relative expression of long non-coding RNA (lncRNA) ADAMTS9-antisense RNA 2 (ADAMTS9-AS2) was assessed via quantitative real-time polymerase chain reaction. ADAMTS9-AS2 knockdown was performed to confirm its function in hPDLCs. Mechanical compression induced changes in the morphology of hPDLCs. It also promoted migration and simultaneous upregulation of FN and downregulation of ADAMTS9, a fibronectinase. The mouse OTM model showed the same expression patterns of the two proteins on the compression side of the periodontium of the moved teeth. RNA sequencing revealed that lncRNA ADAMTS9-AS2 expression was significantly upregulated in hPDLCs under mechanical compression. After knocking down ADAMTS9-AS2, hPDLCs migration was significantly inhibited. ADAMTS9 expression was increased as FN expression decreased compared to that in the control group. Moreover, knockdown of ADAMTS9-AS2 reduced the effect of mechanical compression on hPDLCs migration and reversed the expression change of ADAMTS9 and FN. RNA immunoprecipitation revealed direct binding between ADAMTS9-AS2 and ADAMTS9 protein. Our study suggests that mechanical compression induces the expression of ADAMTS9-AS2, which directly binds to ADAMTS9 and inhibits its function, leading to the promotion of downstream FN expression and ECM remodeling to facilitate hPDLCs migration and maintain the stability of the periodontium.