Interleukin (IL)-1 beta, IL-6, tumor necrosis factor-alpha, epidermal growth factor, and beta 2-microglobulin levels are elevated in gingival crevicular fluid during human orthodontic tooth movement

Exploring biological mechanisms in orthodontic tooth movement: Bridging the gap between basic research experiments and clinical applications - A comprehensive review

OBJECTIVES

The molecular mechanisms behind orthodontic tooth movements (OTM) were investigated by clarifying the role of chemical messengers released by cells.

METHODS

Using the Cochrane library, Google scholar, and PubMed databases, a literature search was conducted, and studies published from 1984 to 2024 were considered.

RESULTS

Both bone growth and remodeling may occur when a tooth is subjected to mechanical stress. These chemicals have a significant effect on the stimulation and regulation of osteoblasts, osteoclasts, and osteocytes during alveolar bone remodeling. This regulation can take place in pathological conditions, such as periodontal diseases, or during OTM alone. This comprehensive review outlines key molecular mechanisms underlying OTM and explores various clinical assumptions associated with specific molecules and their functional domains during this process. Furthermore, clinical applications of certain molecules such as relaxin, prostaglandin E (PGE), and interleukin-1β (IL-1β) in accelerating OTM have been reported. Our findings underscore the existing gap between OTM clinical applications and basic research investigations.

CONCLUSION

A comprehensive understanding of orthodontic treatment is enriched by insights into biological systems. We reported the activation of osteoblasts, osteoclast precursor cells, osteoclasts, and osteocytes in response to mechanical stress, leading to targeted cellular and molecular interventions and facilitating rapid and regulated alveolar bone remodeling during tooth movement. Despite the shortcomings of clinical studies in accelerating OTM, this review highlights the crucial role of biological agents in this process and advocates for prioritizing high-quality human studies in future research to gain further insights from clinical trials.

Assessment of salivary tumor necrosis factor-alpha level in the initial stages of treatment with fixed appliances and clear aligners

OBJECTIVES

To assess and compare the tumor necrosis factor-alpha (TNF-α) levels in saliva samples during the initial stages of orthodontic treatment with fixed orthodontic appliances (FAs) and clear aligners (CAs).

MATERIALS AND METHODS

This longitudinal study comprised 40 patients (22 males, 18 females, mean age 22 ± 7 years) who were categorized into two equal-sized groups. Group A comprised 20 patients treated with FA, and Group B comprised 20 patients treated with CA. Unstimulated saliva was collected before the intiation of treatment and then collected again after the placement of the FA/CA at 24 hrs, 7th day, and on the 21st day in both groups. TNF-α levels were determined through ELISA.

STATISTICAL ANALYSIS

The data were subjected to statistical analysis. For intragroup comparison of TNF-α at different time points, the Wilcoxon matched-pairs signed-rank test was used, and for intergroup comparison of FAs and CAs at different time points, the Mann-Whitney U test was used.

RESULTS

TNF-α levels in the saliva increased significantly at 24 hours, followed by a decline on the 7th day and 21st day in both groups. Changes in TNF-α levels were significantly higher in the FA group than those in the CA group at different time points.

CONCLUSION

This study showed that the salivary TNF-α levels increased significantly during the initial stages of FA and CA treatment at different time points. The mean salivary TNF-α level in both FA and CA groups increased significantly at 24 hours, followed by a decline on the 7th day and then on the 21st day. There was a significant difference between the FA and CA treatment, where the CAs showed a significantly low level of TNF-α in saliva at different intervals of time when compared to the FAs.

A narrative review of the effects of vitamin D3 on orthodontic tooth movement: Focus on molecular and cellular mechanisms

Orthodontic tooth movement (OTM) is a critical process in dental alignment, driven by the application of calibrated orthodontic forces. This study delves into the intricate molecular and cellular mechanisms by which vitamin D3 influences OTM. Vitamin D3 is identified as a critical regulator in bone metabolism, enhancing osteoblast activity and bone formation while also modulating osteoclast quantity and RANKL expression, essential for the remodeling of the alveolar bone. The precise mechanisms through which vitamin D3 facilitates these processes are explored, highlighting its potential in accelerating bone remodeling and, consequently, tooth alignment. This comprehensive review underscores vitamin D3's anabolic impact on bone metabolism and its pivotal role in the synthesis and mineralization processes governed by osteoblasts. The findings illuminate vitamin D3's promise in augmenting orthodontic therapy, suggesting its utility in improving treatment efficiency and reducing duration. However, the need for further research into the optimal application of vitamin D3 in orthodontics is emphasized, particularly concerning dosage, timing, and delivery methods.

Biomechanical Considerations in the Orthodontic Treatment of a Patient with Stabilised Stage IV Grade C Generalised Periodontitis: A Case Report

Orthodontic treatment of periodontally compromised patients presents unique challenges, including controlling periodontal inflammation, applying appropriate force, designing an effective dental anchorage, and maintaining treatment results. Deteriorated periodontal support leads to alterations in the biological responses of teeth to mechanical forces, and thus orthodontists must take greater care when treating patients with periodontal conditions than when treating those with a good periodontal status. In this article, we report the case of a 59-year-old woman with stabilised Stage IV grade C generalised periodontitis characterised by pathological tooth migration (PTM). The assessment, planning, and treatment of this patient with orthodontic fixed appliances is described. Moreover, the anchorage planning and biomechanical considerations are detailed. Specific orthodontic appliances were employed in this case to produce force systems for achieving precise tooth movement, which included a cantilever, mini-screws, and a box loop. Careful application of those appliances resulted in satisfactory aesthetic and functional orthodontic outcomes in the patient. This case highlights the importance of multidisciplinary collaboration in the treatment of patients with severe periodontitis and the potential for tailored biomechanical approaches in orthodontic treatment to furnish good outcomes.

Stem cells derived from human exfoliated deciduous teeth-based media in a rat root resorption model

OBJECTIVE

Root resorption may occur during orthodontic treatment. Herein, we investigated the effect of a culture supernatant of stem cells derived from human exfoliated deciduous teeth on root resorption.

DESIGN

Twelve 8-week-old male Sprague-Dawley rats were used, and their maxillary first molars were pulled with excessive orthodontic force to induce root resorption. On days 1 and 7 after traction initiation, stem cells derived from human exfoliated deciduous teeth and alpha minimum essential medium (control group) were administered. After 14 days, the maxillary bone was evaluated for tooth movement. The expression of osteoprotegerin, receptor activator of nuclear factor κB ligand, tumor necrosis factor α, interleukin 1β, interleukin 6, and interleukin 17 was evaluated on the compression side and tension side.

RESULTS

No significant difference in tooth movement was observed between the two groups. Root resorption decreased in the group administered the culture supernatant compared with in the control. Immunohistochemical staining revealed increased osteoprotegerin expression and decreased receptor activators for nuclear factor κB ligand, tumor necrosis factor α, interleukin 1β, interleukin 6, and interleukin 17 on the compression side and tension side.

CONCLUSIONS

Administration of stem cells derived from human exfoliated deciduous teeth affected the expression of osteoprotegerin, receptor activator of nuclear factor κB ligand, tumor necrosis factor α, interleukin 1β, interleukin 6 and interleukin 17; hence, these stem cells may inhibit root resorption by regulating their expression.

Role of vitamin D for orthodontic tooth movement, external apical root resorption, and bone biomarker expression and remodeling: A systematic review

Objective

: This systematic review aimed to evaluate the correlation between vitamin D levels and the rate of tooth movement, external apical root resorption, bone biomarker expression, and bone remodeling.

Methods

: Three databases (PubMed, Scopus, and Web of Science) were systematically searched from inception until 14th March 2023 to identify studies investigating the correlation between orthodontic tooth movement and vitamin D in animals and humans. The quality assessment was made in accordance with the Joanna Briggs Institute Critical Appraisal Checklist.

Results

: Overall, 519 records were identified, and 19 were selected for the qualitative synthesis. Eleven studies investigated the effect of local administration (injections in the periodontal ligament, to the gingiva distal to the teeth, or submucosae palatal area) and systemic administration (oral supplementation) of vitamin D on tooth movement, external apical root movement, pro-inflammatory cytokines, and bone remodeling factors. The remaining eight studies investigated the correlation between serum vitamin D levels and salivary vitamin D levels on bone turnover markers and tooth movement.

Conclusions

: The findings of this systematic review support that vitamin D3 local injections might increase the rate of tooth movement via the receptor activator of the nuclear factor-kB/osteoprotegerin axis. However, the non-uniform study designs and the different protocols and outcome methods make it challenging to draw reliable conclusions.

Orthodontically induced changes to the genetic profile in periodontal ligament tissue and cytokine release in gingival crevicular fluid - A pilot investigation

Background/purpose

It has been known that genetic factors influence orthodontic tooth movement, however, scientific research on humans is lacking. Therefore, this study aimed to investigate dynamic changes to the genetic profile in human periodontal ligament (PDL) tissue and cytokine release in gingival crevicular fluid (GCF) during the first 28 days of orthodontic treatment.

Materials and methods

Fifteen teeth from three patients were recruited. Full-mouth fixed appliances with extraction of four premolars and one maxillary third molar was planned for orthodontic treatment. GCF collection and tooth extraction were performed following force application for 0, 1, 3, 7, and 28 days. GCF was analyzed using multiplex immunoassay for 27 cytokines. PDL tissue was collected after extraction and submitted for RNA exome-sequencing using Illumina sequencing platform. Further analysis of differentially expressed genes (DEGs), gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, and heatmaps were conducted.

Results

GCF cytokine levels varied among three patients; some patients exhibited a peak cytokine level on Day 0 whereas others did so on Days 1-3. In RNA exome sequencing data, GO and KEGG analyses showed that genes associated with sensory receptors were upregulated on Day 1, genes involved in bone remodeling were upregulated on Days 3 and 28, and genes related to osteoclast differentiation were upregulated on Day 7.

Conclusion

RNA sequencing data demonstrate that the specific types of genes are expressed at different time points, whereas the data on cytokine changes show a large variation in concentration levels and dynamic change patterns among the patients.

Accelerated Orthodontics: Stepping Into the Future Orthodontics

Orthodontic treatment signifies a transformative journey for individuals seeking not only enhanced oral health but also a boost in aesthetics and self-confidence. Nonetheless, the protracted timeline associated with conventional orthodontic care has been a persistent concern for both patients and practitioners. In this comprehensive review, we embark on an exploration of innovative strategies aimed at expediting orthodontic tooth movement (OTM). By doing so, we aspire to curtail treatment duration and mitigate potential risks, ultimately culminating in an elevated and more fulfilling patient experience. Traditionally, orthodontists heavily leaned on surgical techniques to hasten tooth movement. However, the recent landscape of orthodontics has been profoundly shaped by technological advancements and groundbreaking research findings, ushering in an era characterized by the embrace of minimally invasive approaches. These progressive methodologies encompass procedures like Piezocision, Discision, and Microosteoperforation (Alveocentesis). Beyond the obvious benefits of reduced patient discomfort, these techniques significantly truncate treatment periods, a development that addresses a primary concern of many patients. Moreover, this review delves into non-invasive alternatives, including cyclic vibrations, photobiomodulation, direct light electric current, and static or pulsed magnetic fields, as well as systemic and local administration of biological substances and hormones, all of which hold substantial promise in optimizing OTM. Furthermore, our exploration extends to a diverse spectrum of medications that have demonstrated their efficacy in expediting OTM. These encompass NSAIDs, acetaminophen, corticosteroids, bisphosphonates, herbal medicine biomaterials, and synthetic biomaterials like graphene dioxide. Every technique and medication is subjected to meticulous evaluation, taking into account its indications, contraindications, advantages, disadvantages, clinical implications, and limitations. Through this review, we endeavor to equip orthodontic professionals with a profound understanding of these innovative strategies. By doing so, we enable them to make informed decisions, tailored meticulously to meet the unique needs of each patient. In an ever-evolving field like orthodontics, staying abreast of these advancements becomes paramount, ultimately contributing to heightened treatment efficacy and enhanced patient satisfaction. The adoption of these innovative strategies not only holds the potential for improved clinical outcomes but also champions a patient-centric approach that could fundamentally reshape the landscape of orthodontic care.

The Effect of Varied Time Interval and Micro-Current (Direct) on the Level of Biomarker (IL-6) and Rate of Tooth Movement: An Animal Study

INTRODUCTION

Exogenous application of direct current (DC) on piezoelectric biopolymers results in biochemical modifications in the intracellular/extracellular regions which profoundly affects the pace of bone turnover. A qualitative examination of DC (waveform and frequency) provides ideal qualities of current.

MATERIAL AND METHOD

20 female Wistar rats (Rattus norvegicus) were randomly selected and divided into control (group 1-4 rats) with orthodontic appliance (OA) and experimental groups (OA + Micro-current (MC). Experimental groups were subdivided into four groups (group 2-20 μA/5 sec, 3-20 μA/10 sec, 4-15 μA/5 sec, 5-15 μA/10 sec with four rats in each). The tooth movement was recorded every 24th hours for 7 days. Gingival crevicular fluid (GCF) was collected 6 hr, 12 hr, 24 hr, 3rd day and 168 hrs with the absorbent paper points at specific location around the tooth in control and experiment groups. Histopathological analysis was done on 168 hrs to assess the osteoclastic activity around the root. Interleukin-6 (IL-6) concentration was accessed using enzyme-linked immunosorbent assay (ELISA). The data were subjected to one-way ANOVA and Tukey's posthoc test.

RESULTS

There was a statistically significant difference in tooth movement, group 3 (20 μA/10 sec) showed an increased rate of tooth movement on the 168 hrs. The level of IL-6 was maximum on 72 hrs in experimental group 3.

CONCLUSION

The study showed time interval/frequency, the waveform, and the amount of current play a significant role in determining bone turnover and rate of tooth movement.

Impact of Low-Level Laser Therapy on Orthodontic Tooth Movement and Various Cytokines in Gingival Crevicular Fluid: A Split-Mouth Randomized Study

BACKGROUND AND OBJECTIVES

A few investigations have detailed the influence of low-level laser therapy (LLLT) on orthodontic tooth movement (OTM), with varying results. The objectives of this study were twofold: to assess the impact of LLLT on OTM and various cytokine levels in gingival crevicular fluid and to contrast the pain levels experienced by patients receiving orthodontic treatment with and without LLLT.

MATERIALS AND METHODS

This split-mouth randomized controlled prospective study comprised 40 patients with an average age of 19.7±2.4 years with Angle Class I malocclusion combined with bimaxillary protrusion who were advised for extraction of the maxillary first premolar and bilateral canine distalization. The control-side canine was distalized solely by the coil spring. On the test arm, a low-level gallium-aluminum-arsenide semiconductor diode laser operating at 980 nm and 100 mW with a continuous-wave energy of 8 J/cm2 was used. The canine distalization on either side was measured with a digital caliper following the first premolar extraction (TO), one month after treatment (TOTM1), two months later (TOTM2), and three months later (TOTM3). The gingival index and the level of various cytokines were determined by an enzyme-linked immunosorbent assay at the beginning of the study, on the third and seventh days, and at four, eight, and 12 weeks following the canine distalization. The intra-group and inter-group comparisons were carried out using one-way analysis of variance (ANOVA) and t-tests, respectively, at a 5% significance level.

RESULTS

The results show a highly statistically significant difference in the extent of canine distalization in the test group (TOTM1=2.92±0.44; TOTM2=1.04±0.1; TOTM3​=0.62±0.21 mm) in contrast to the control group (TOTM1=3.23±0.8; TOTM2=2.65±0.2; TOTM3​​​​=2.11±0.24 mm) (p<0.01). After three months of canine distalization, the laser and control group had 34 and 27 patients with mild gingivitis, respectively. Interleukin-1β and interleukin-6 concentrations surged with values of 0.74±0.13 and 0.049±0.001 pg/g at seven days following treatment in the laser group, respectively. The difference in tumor necrosis factor concentration between the groups was shown to be highly statistically significant in all treatment phases (p<0.001). The differences in the epidermal growth factor and microglobulin levels were found to be statistically significant within both groups from T0 to T5. The average visual analog scale (VAS) scores at several subsequent evaluations of the laser and control groups were found to be highly statistically significant.

CONCLUSION

The findings imply that when the periodontal microenvironment is stimulated by orthodontic force, several paramount cytokines are released, triggering an ordered sequence of biological processes that appear to expedite OTM with reduced associated pain.

Docosahexaenoic acid inhibits TNF-α-induced osteoclast formation and orthodontic tooth movement through GPR120

Docosahexaenoic acid (DHA) is an omega-3 fatty acid that has a range of positive impacts on human health, including anti-inflammatory effects and inhibition of osteoclast formation via G-protein-coupled receptor 120 (GPR120). Orthodontic force was reported to induce tumor necrosis factor-α (TNF-α) expression, which activates osteoclast differentiation during orthodontic tooth movement (OTM). The aim of this study was to investigate the influence of DHA on TNF-α-induced osteoclast formation and OTM in vivo. We examined osteoclast formation and bone resorption within the calvaria of both wild-type (WT) and GPR120-deficient (GPR120-KO) mice injected with phosphate-buffered saline (PBS), TNF-α, TNF-α and DHA, or DHA. DHA inhibited TNF-α-induced osteoclast formation and bone resorption in WT mice but had no effect in GPR120-KO mice. OTM experiments were performed in mouse strains with or without regular injection of DHA, and the effects of DHA on osteoclast formation in the alveolar bones during OTM were examined. DHA also suppressed OTM in WT but not GPR120-KO mice. Our data showed that DHA suppresses TNF-α-induced osteoclastogenesis and bone resorption via GPR120. TNF-α has considerable significance in OTM, and therefore, DHA may also inhibit TNF-α-induced osteoclast formation and bone resorption in OTM.

Evaluation of delphinidin as a storage medium for avulsed teeth

BACKGROUND

Delphinidin (DP), an anthocyanidin found in blueberries, has antioxidant and anti-inflammatory effects. This study aimed to investigate the efficacy of DP as a storage medium for avulsed teeth.

METHODS

Human periodontal ligament cells were cultured and exposed to DP solution (10, 50, and 100 μM), Dulbecco's modified Eagle's medium, Hank's balanced salt solution and tap water. Cell counting kit-8 assays were performed after 0.5, 1, 6, and 24 h to measure the cell viability. Nitric oxide assays and gelatin zymography were performed to evaluate the anti-inflammatory effects of DP. Reverse transcription-polymerase chain reaction was used to determine the expression levels of inflammatory cytokines.

RESULTS

The viability of periodontal ligament cells was greatest at 100 μM DP. At 1 h, 100 μM DP decreased nitric oxide synthesis (p < .0167). Matrix metallopeptidase-9 activity was inhibited by DP in a dose-dependent manner (p < .0167). Moreover, treatment with 100 μM DP decreased the expression levels of tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-8 in periodontal ligament cells (p < .0167).

CONCLUSIONS

Within the limits of this study, DP preserved the viability and suppressed the inflammatory response of periodontal ligament cells. These findings suggest that DP could be promising for preservation of avulsed teeth.

A randomized controlled trial evaluating the effect of two low-level laser irradiation protocols on the rate of canine retraction

The objective of this study was to evaluate the canine retraction rate with two low-level laser therapy (LLLT) irradiation protocols, involving both a high and a low application frequency. Twenty patients were randomly divided into two equal groups. In Group A, one side of the maxillary arch randomly received LLLT on days 0, 3, 7, 14, and every 2 weeks thereafter, whereas in Group B, one side received LLLT every 3 weeks. Tooth movement was checked every three weeks since the onset of canine retraction, over the 12-week study period. Moreover, Interleukin-1β (IL-1β) levels in the gingival crevicular fluid were assessed. Results revealed a significant increase in the canine retraction rate on the laser sides of groups A and B, in comparison with the control sides (p < 0.05), with no significant differences reported between the laser sides in both groups (p = 0.08–0.55). Also, IL-1β levels were significantly higher on the laser sides of both groups, in comparison with the control sides (p < 0.05). Therefore, LLLT can effectively accelerate tooth movement, with both frequent and less frequent applications, which is attributed to an enhanced biological response as reflected by the elevated IL-1β levels on the compression sides.

Impact of phosphorylation of heat shock protein 27 on the expression profile of periodontal ligament fibroblasts during mechanical strain

PURPOSE

Orthodontic tooth movement is a complex process involving the remodeling of extracellular matrix and bone as well as inflammatory processes. During orthodontic treatment, sterile inflammation and mechanical loading favor the production of receptor activator of NF-κB ligand (RANKL). Simultaneously, expression of osteoprotegerin (OPG) is inhibited. This stimulates bone resorption on the pressure side. Recently, heat shock protein 27 (HSP27) was shown to be expressed in the periodontal ligament after force application and to interfere with inflammatory processes.

METHODS

We investigated the effects of phosphorylated HSP27 on collagen synthesis (COL1A2 mRNA), inflammation (IL1B mRNA, IL6 mRNA, PTGS2 protein) and bone remodeling (RANKL protein, OPG protein) in human periodontal ligament fibroblasts (PDLF) without and with transfection of a plasmid mimicking permanent phosphorylation of HSP27 using real-time quantitative polymerase chain reaction (RT-qPCR), western blot and enzyme-linked immunosorbent assays (ELISAs). Furthermore, we investigated PDLF-induced osteoclastogenesis after compressive strain in a co-culture model with human macrophages.

RESULTS

In particular, phosphorylated HSP27 increased gene expression of COL1A2 and protein expression of PTGS2, while IL6 mRNA levels were reduced. Furthermore, we observed an increasing effect on the RANKL/OPG ratio and osteoclastogenesis mediated by PDLF.

CONCLUSION

Phosphorylation of HSP27 may therefore be involved in the regulation of orthodontic tooth movement by impairment of the sterile inflammation response and osteoclastogenesis.

Control of Orthodontic Tooth Movement by Nitric Oxide Releasing Nanoparticles in Sprague-Dawley Rats

Orthodontic treatment commonly requires the need to prevent movement of some teeth while maximizing movement of other teeth. This study aimed to investigate the influence of locally injected nitric oxide (NO) releasing nanoparticles on orthodontic tooth movement in rats.

MATERIALS AND METHODS

Experimental tooth movement was achieved with nickel-titanium alloy springs ligated between the maxillary first molar and ipsilateral incisor. 2.2 mg/kg of silica nanoparticles containing S-nitrosothiol groups were injected into the mucosa just mesial to 1^st molar teeth immediately prior to orthodontic appliance activation. NO release from nanoparticles was measured in vitro by chemiluminescence. Tooth movement was measured using polyvinyl siloxane impressions. Bones were analyzed by microcomputed tomography. Local tissue was assessed by histomorphometry.

RESULTS

Nanoparticles released a burst of NO within the first hours at approximately 10 ppb/mg particles that diminished by 10 × to approximately 1 ppb/mg particles over the next 1-4 days, and then diminished again by tenfold from day 4 to day 7, at which point it was no longer measurable. Molar but not incisor tooth movement was inhibited over 50% by injection of the NO releasing nanoparticles. Inhibition of molar tooth movement occurred only during active NO release from nanoparticles, which lasted for approximately 1 week. Molar tooth movement returned to control levels of tooth movement after end of NO release. Alveolar and long bones were not impacted by injection of the NO releasing nanoparticles, and serum cyclic guanosine monophosphate (cGMP) levels were not increased in animals that received the NO releasing nanoparticles. Root resorption was decreased and periodontal blood vessel numbers were increased in animals with appliances that were injected with the NO releasing nanoparticles as compared to animals with appliances that did not receive injections with the nanoparticles.

CONCLUSION

Nitric oxide (NO) release from S-nitrosothiol containing nanoparticles inhibits movement of teeth adjacent to the site of nanoparticle injection for 1 week. Additional studies are needed to establish biologic mechanisms, optimize efficacy and increase longevity of this orthodontic anchorage effect.

Evaluation of periodontal parameters and gingival crevicular fluid cytokines in children with anterior open bite receiving passive orthodontic treatment with a spur

Objective

To evaluate clinical parameters and gingival crevicular fluid (GCF) cytokines in children with anterior open bite receiving passive orthodontic treatment with spurs.

Methods

Twenty children with indications for interceptive orthodontic treatment, an anterior open bite, and good oral hygiene and periodontal health were included in this study. GCF samples were collected from the mandibular and maxillary central incisors before (baseline) and 24 hours and 7 days after spur bonding. Clinical and periodontal examinations and cytokine analyses were performed.

Results

At 7 days after spur attachment, gingival bleeding in the mandibular group was increased relative to that in the maxillary group. Visible plaque was correlated with gingival bleeding at 7 days and the GCF volume at 24 hours after spur attachment. Compared with those at baseline, interleukin (IL)-8 levels in the maxillary group and IL-1β levels in both tooth groups increased at both 24 hours and 7 days and at 7 days, respectively. At 24 hours, IL-8, IL-1β, and IL-6 levels were higher in the maxillary group than in the mandibular group. Cytokine production was positively correlated with increased GCF volume, but not with gingival bleeding, visible plaque, or probing depth.

Conclusions

Although orthodontic treatment with spurs in children resulted in increased gingival bleeding around the mandibular incisors, IL levels were higher around the maxillary incisors and not correlated with periodontal parameters. Increased cytokine levels in GCF may be associated with the initial tooth movement during open bite correction with a passive orthodontic appliance in children.

Open bite

Micro-Osteoperforations Induce TNF-α Expression and Accelerate Orthodontic Tooth Movement via TNF-α-Responsive Stromal Cells

Micro-osteoperforations (MOPs) have been reported to accelerate orthodontic tooth movement (OTM), and tumor necrosis factor (TNF)-α has been reported to play a crucial role in OTM. In this report, the influence of MOPs during OTM was analyzed. We evaluated the expression of TNF-α with and without MOPs by RT-PCR analysis. A Ni-Ti closed coil spring was fixed between the maxillary left first molar and the incisors as an OTM mouse model to move the first molar in the mesial direction. MOPs were prepared on the lingual side and mesial side of the upper first molars. Furthermore, to investigate the target cell of TNF-α for osteoclast formation during OTM with MOPs in vivo, we created four types of chimeric mice in which bone marrow of wild-type (WT) or TNF receptor 1- and 2-deficient mice (KO) was transplanted into lethally irradiated WT or KO mice. The results showed that MOPs increased TNF-α expression, the distance of tooth movement and osteoclast formation significantly. Furthermore, mice with TNF-α-responsive stromal cells showed a significant increase in tooth movement and number of osteoclasts by MOPs. We conclude that MOPs increase TNF-α expression, and tooth movement is dependent on TNF-α-responsive stromal cells.

Association between Polymorphisms in the IL-1β, TNFRSF11B, CASP1, and IL-6 Genes and Orthodontic-Induced External Apical Root Resorption

Orthodontic-induced external apical root resorption (EARR) is a severe condition affecting the roots of the teeth, whose genetic causes have been inconclusive to date. The aim of the present study was to assess the influence of selected single nucleotide polymorphisms (SNPs) IL-1β, TNFRSF11B, CASP1, and IL-6 genes on post-orthodontic EARR. A sample of 101 patients with clearly assessable orthopantomograms and lateral cephalometric radiographs taken before and at the end of the orthodontic treatment was used to evaluate the presence of EARR. The association between genetic polymorphisms and EARR was assessed with the Chi² test. A binary logistic multi-level model was built to evaluate the ability of patient- and tooth-level variables to predict EARR occurrence. The overall prevalence of EARR resulted to be around 40%. Within the limitations of this study, a significant association was found between EARR presence and the SNP for the IL-1β gene but not for the TNFRSF11B, CASP1, and the IL-6 genes. The final multi-level model demonstrated that the SNP for the IL-1β gene increases the odds of developing EARR by around four times. Since there is currently no accurate method to determine which patients will develop EARR prior to orthodontic treatment, further studies are needed to investigate the predictive ability of further genetic variants on EARR development.

Effects of mechanical strain on periodontal ligament fibroblasts in presence of Aggregatibacter actinomycetemcomitans lysate

PURPOSE

Many adult orthodontic patients suffer from periodontitis, which is caused by oral pathogens such as the gram-negative Aggregatibacter actinomycetemcomitans (Agac). Like orthodontic tooth movement, periodontitis is associated with inflammation and alveolar bone remodelling thereby affecting orthodontic treatment. Interactions of both processes, however, are not sufficiently explored, particularly with regard to oxidative stress.

METHODS

After preincubation with Agac lysate for 24 h periodontal ligament fibroblasts (PDLF) were either stretched or compressed for further 48 h simulating orthodontic forces in vitro. We analysed the expression of genes and proteins involved in the formation of reactive oxygen species (NOX-4, ROS) and nitric oxide (NOS-2), inflammation (TNF, IL-6, PTGS-2) and bone remodelling (OPG, RANKL).

RESULTS

Agac lysate elevated the expression of NOX-4, NOS-2, inflammatory IL-6 and PTGS-2 and the bone-remodelling RANKL/OPG ratio during compressive, but not tensile mechanical strain. Agac lysate stimulated pressure-induced inflammatory signalling, whereas surprisingly ROS formation was reduced. Pressure-induced downregulation of OPG expression was inhibited by Agac lysate.

CONCLUSIONS

Agac lysate impact on the expression of genes and proteins involved in inflammation and bone remodelling as well as ROS formation, when PDLF were subjected to mechanical forces occurring during orthodontic tooth movement.

Experimental models of orthodontic tooth movement and their effects on periodontal tissues remodelling

OBJECTIVES

The present study aimed to compare two different models of orthodontic tooth movement (OTM) in rats by evaluating tooth movement efficiency and periodontal tissues remodelling.

DESIGN

Fifteen animals were randomly distributed into 3 groups: control group (untreated); ligature appliance (LA) as experimental OTM using a closed coil spring fixed around maxillary first molar by steel ligature; occlusal appliance (OA) as experimental OTM using a closed coil spring attached on the occlusal surface of the maxillary first molar. After 15 days, all animals were euthanized, and the maxilla of each animal was collected for qPCR, micro-computed tomography, and histological analyses.

RESULTS

Interleukin-1 beta, interleukin-6, and tumor necrosis factor-alpha gene expressions were significantly upregulated in the animals of the LA group as compared to the other groups. No significant difference was observed in tooth displacement between both methods. The LA group presented higher linear bone loss and lower values of bone volume fraction, bone mineral density, trabecular number and increased values of trabecular separation compared to the other groups. The birefringent collagen content in the tension side of the periodontal ligament contained significantly lower collagen content in the LA group than in the control group. Furthermore, on the pressure side, the collagen content was significantly lower in the LA and OA groups than in the control group.

CONCLUSIONS

The OA group presented little or no deleterious effect on periodontal tissues compared to the LA group, suggesting its use may be more reliable for OTM induction in rats for 15 days.

Clinical research: low-level laser therapy in accelerating orthodontic tooth movement

Background

The present study aimed to investigate the effects of low-level laser therapy (LLLT) on orthodontic tooth movement and its correlation with the levels of interleukin-1β (IL-1β), receptor activator of nuclear factor kappa B ligand (RANKL) and osteoprotegerin (OPG) in gingival crevicular fluid (GCF).

Methods

This split-mouth design study included 12 patients scheduled for the extraction of both upper first premolars. Patients were randomly selected for experimental group that received left- or right-side radiation with a diode laser (810 nm wavelength, 100 mW power output, 6.29 J/cm² energy density). Laser treatment was applied on days 0, 7, 14, and 21, after loading the canine retraction forces. GCF concentrations of IL-1β, RANKL, and OPG were analyzed. The upper arch of each patient was scanned with an intraoral scanner to assess tooth movement.

Results

The cumulative tooth movement over 28 days was significantly higher in the laser group than in the control group. We observed significant reductions in OPG levels and increases in IL-1β and RANKL levels in GCF samples on the experimental sides.

Conclusion

With the parameter settings used in this study, LLLT could, to some extent, lead to changes in bone metabolism, which could accelerate orthodontic tooth movement.

Trial registration: Chinese Clinical Trial Registry, ChiCTR2000039594. Registered 2 November 2020—Retrospectively registered, www.chictr.org.cn/edit.aspx?pid=62465&htm=4.

Evaluation of heat shock protein 70 and toll-like receptor 4 expression in gingival crevicular fluid in response to orthodontic forces

OBJECTIVES

The aim of this study was to assess the concentrations of heat shock protein 70 (HSP70) and toll-like receptor 4 (TLR4) during orthodontic tooth movement and to compare their levels with interleukin-1β (IL-1β), a well-known proinflammatory biomarker.

MATERIALS AND METHODS

This study consisted of 20 patients (8 males, 12 females; mean age 14.75 ± 2.34 years) who needed maxillary premolar extraction and segmental canine distalization. Concentrations of HSP70, TLR4, and IL-1β were examined before extraction (T1), at the 1st (T2), 4th (T3), 7th (T4), 14th (T5), and 30th (T6) days of canine retraction by enzyme-linked immunosorbent assay analysis of gingival crevicular fluid samples. Statistical analyses were performed with repeated measure ANOVA and Spearman's rank correlation coefficient analysis (p < 0.05).

RESULTS

HSP70 increased gradually from T1 to T6 and showed significant differences between T1-T6 and T2-T6 (T1:3.28 ± 0.92 ng/ml; T2:3.72 ± 0.66 ng/ml; T6:9.35 ± 2.45 ng/ml). The lowest TLR4 concentration was at T1, peaked at T3 and remained constant afterwards with significant differences between T1-T3, T1-T4, and T1-T6 (T1:0.71 ± 0.02 pg/ml; T3:1.04 ± 0.11 pg/ml; T4:0.95 ± 0.06 pg/ml; T6:1.00 ± 0.07 pg/ml). IL-1β increased from T1 to T6 with significant differences between T1-T4, T1-T5, and T1-T6 (T1:55.71 ± 5.48 pg/ml; T4:100.11 ± 16.92 pg/ml; T5:103.71 ± 23.19 pg/ml; T6:125.12 ± 22.04 pg/ml). The increase in HSP70 and TLR4 from T2-T3 showed a significant correlation (r = 0.598; p = 0.005).

CONCLUSIONS

The increased levels of HSP70, TLR4, and IL-1β show the contribution of these mediators to the inflammatory response from the early stages of orthodontic tooth movement.

CLINICAL RELEVANCE

The regulation of HSP70, TLR4, and/or IL-1β secretion during orthodontic force application could provide alterations for desired optimal tooth movement.

Mechanistic Insight into Orthodontic Tooth Movement Based on Animal Studies: A Critical Review

Alveolar bone remodeling in orthodontic tooth movement (OTM) is a highly regulated process that coordinates bone resorption by osteoclasts and new bone formation by osteoblasts. Mechanisms involved in OTM include mechano-sensing, sterile inflammation-mediated osteoclastogenesis on the compression side and tensile force-induced osteogenesis on the tension side. Several intracellular signaling pathways and mechanosensors including the cilia and ion channels transduce mechanical force into biochemical signals that stimulate formation of osteoclasts or osteoblasts. To date, many studies were performed in vitro or using human gingival crevicular fluid samples. Thus, the use of transgenic animals is very helpful in examining a cause and effect relationship. Key cell types that participate in mediating the response to OTM include periodontal ligament fibroblasts, mesenchymal stem cells, osteoblasts, osteocytes, and osteoclasts. Intercellular signals that stimulate cellular processes needed for orthodontic tooth movement include receptor activator of nuclear factor-κB ligand (RANKL), tumor necrosis factor-α (TNF-α), dickkopf Wnt signaling pathway inhibitor 1 (DKK1), sclerostin, transforming growth factor beta (TGF-β), and bone morphogenetic proteins (BMPs). In this review, we critically summarize the current OTM studies using transgenic animal models in order to provide mechanistic insight into the cellular events and the molecular regulation of OTM.

Tissue-specific biomarkers in gingival crevicular fluid are correlated with external root resorption caused by constant mechanical load: an in vivo study

OBJECTIVES

This study investigated the association of changes in cementum protein-1 (CEMP-1), dentine phosphoprotein (DPP), and c-terminal cross-linked telopeptide of type I collagen (CTX-I) levels in human gingival crevicular fluid (GCF) under constant load with external root resorption volume and amount of tooth movement.

MATERIALS AND METHODS

In total, 11 healthy adult patients (mean age, 23.5 years [range, 18.3-37.7]; four men and seven women) were enrolled. GCF samples were obtained from premolars at T0, T1 (1 day), T2 (1 week), T3 (2 weeks), T4 (4 weeks), and T5 (8 weeks) under constant 100-gm buccal tipping force. Opposite premolars were used as controls. Teeth were extracted at T5, followed by quantification of external root resorption volume and histological analysis.

RESULTS

In the test group, T5/T0 ratios of CEMP-1 and DPP levels, differential CEMP-1 levels between T5 and T0, and differential DPP levels between T2 and T0 correlated positively with root resorption volume (r = 0.734, 0.730, 0.627, and 0.612, respectively, all p < 0.05). CEMP-1 levels at T0 and T3 correlated negatively with root resorption volume (r = -0.603 and -0.706; all p < 0.05). CTX-I levels at T5 correlated positively with the amount of tooth movement (r = 0.848, p < 0.01).

CONCLUSIONS

Alterations in CEMP-1 and DPP levels in human GCF at specific timepoints during orthodontic treatment may be associated with different degrees of external root resorption.

CLINICAL RELEVANCE

This study demonstrates that changes in the levels of tissue-specific biomarkers in GCF may facilitate early detection of external root resorption during orthodontic tooth movement.

Performance comparison of vibration devices on orthodontic tooth movement - A systematic review and meta-analysis

Background

To evaluate the efficiency of vibratory devices in altering rate of orthodontic tooth movement.

Methods

A literature search up to January 31, 2020 was conducted in three electronic databases: PubMed, Cochrane Central Register of Controlled Trials (CENTRAL) and Science Direct, to identify studies on vibratory devices reporting any alteration in tooth movement as a primary outcome. Only articles published in English language were included. A meta-analysis was done to compare the amount of tooth movement (in mm) in patients treated with vibratory devices compared to control groups, to quantify weighted treatment effects.

Results

A total of two split mouth studies, six parallel arm randomized control trials (RCT) one split mouth RCT, and three regular RCTs were assessed qualitatively. Quantitative assessment was done for 8 randomized trials using a forest plot (310 patients). Pooled data showed increase in the amount of tooth movement by 0.34 ​mm (95% CI:0.25,0.42). There was a statistically significant difference noted for this result at p ​< ​0.00001.

Conclusion

Current evidence suggests a moderate to high level of certainty in regard to included studies in this systematic review and meta-analysis. Vibratory devices when used in conjunction with fixed orthodontic appliances show significant increase in the rate of tooth movement. These devices can be used by clinicians to reduce treatment duration and patient discomfort.

PROSPERO registration

CRD42020169675.

Suppressing ROS generation by apocynin inhibited cyclic stretch-induced inflammatory reaction in HPDLCs via a caspase-1 dependent pathway

It has been reported that cyclic stretch could induce inflammatory reaction in human periodontal ligament cells (HPDLCs). Though reactive oxygen species (ROS) has been reported to be involved in pathogen-induced periodontal inflammatory reaction, its role in the force-related periodontal diseases has not been well clarified. This study inspected the role of ROS in the cyclic stretch-induced inflammatory reaction in HPDLCs and studied the inhibitory effect of antioxidant apocynin on this inflammatory reaction. Results confirmed that cyclic stretch induced inflammatory reaction and production of ROS in HPDLCs. This inflammatory reaction was inhibited by apocynin through blocking the production of ROS. The cyclic stretch also induced the expression of caspase-1 and NLRP3 inflammasome, which could also be inhibited by apocynin. Moreover, the cyclic stretch-induced inflammatory reaction was inhibited by caspase-1 inhibitor. Collectively, it is the first time that increased intracellular ROS was proved to play as an intermediate signal in the cyclic stretch-induced inflammatory reaction in HPDLCs, via a caspase-1-dependent pathway. The inhibitory effect of apocynin on the cyclic stretch-induced inflammatory reaction in HPDLCs shows the potential of antioxidants in the treatment of force-related periodontal inflammatory diseases.

Vibration synergistically enhances IL-1β and TNF-α in compressed human periodontal ligament cells in the frequency-dependent manner

Objectives

To investigate whether mechanical vibration at 30 or 60 Hz combined with compressive force alter IL-1β and TNF-α expression in human periodontal ligament (hPDL) cells.

Methods

hPDL cells isolated from the roots of first premolar teeth extracted from four independent donors were cultured and exposed to vibration (0.3 g, 20 min per cycle, every 24 h for 3 cycles) at 30 or 60 Hz (V30 or V60), 2.0 g/cm² compressive force for 2 days (CF), or a combination of compressive force and vibration at 30 Hz or 60 Hz (V30CF or V60CF). Quantitative real-time polymerase chain reaction (qPCR) and enzyme-linked immunosorbent assays (ELISAs) were used to determine IL-1β and TNF-α mRNA and protein, respectively.

Results

The levels of IL-1β and TNF-α did not alter in groups V30 and V60. While, they were upregulated in groups CF, V30CF and V60CF. In addition, IL-1β mRNA and TNF-α mRNA and protein were expressed at significantly higher levels in group V30CF compared to CF group. However, IL-1β protein levels between V30CF and CF groups did not reach statistical significance.

Conclusions

30 Hz vibration had the synergistic effects with compressive force on the upregulation of IL-1β mRNA and TNF-α mRNA and protein in PDL cells, while 60 Hz vibration did not have this synergistic effect.

Micro-osteoperforations and Its Effect on the Rate of Tooth Movement: A Systematic Review

Prolonged orthodontic treatments have inconvenienced patients and clinicians alike. Surgically assisted techniques for accelerating orthodontic tooth movement have shown promising results in the literature over the years. The minimally invasive nature of micro-osteoperforations (MOPs), however, for enhanced orthodontic tooth movement has recently gained momentum, with many clinical trials conducted on both animals and humans. An electronic search was performed to extract papers using PubMed, Google Scholar, Scopus, and Web of Science. The keywords that were used included “MOP,” “accelerating tooth movement,” “orthodontic tooth movement,” and “regional acceleratory phenomenon.” The studies that met our inclusion criteria were extracted and evaluated in this review. MOPs have been proven time and again, in animal and human studies alike, to increase the rate of orthodontic tooth movement. The application of perforations to cortical bone present in the pathway of teeth, which are specifically to be moved creates transient osteopenia. This reduces the density of the cortical bone, hence speeding up the rate of orthodontic tooth movement. Many techniques have been implemented and perfected to enhance orthodontic tooth movement and shorten the treatment time in the literature. MOPs have proven to be a universally applied, nontechnical, repeatable, and minimally invasive method of accelerating tooth movement, with extremely minimal consequences.

Effect of orthodontic forces on levels of enzymes in gingival crevicular fluid (GCF): A systematic review

Objective:

Orthodontic force application releases multiple enzymes in gingival crevicular fluid (GCF) for activation, resorption, reversal, deposition of osseous elements and extracellular matrix degradation. The current systematic review critically evaluated all existing evidence on enzymes in orthodontic tooth movement.

Methods:

Literature was searched with predetermined search strategy on electronic databases (PubMed, Scopus, Embase), along with hand search.

Results:

Initial search identified 652 studies, shortlisted to 52 studies based on PRISMA. Quality assessment further led to final inclusion of 48 studies (13 moderately and 35 highly sensitive studies). Primary outcomes are significant upregulation in GCF levels of enzymes-aspartate aminotransferase (AST), alkaline phosphatase (ALP), matrix metalloproteinases (MMPs), lactate dehydrogenase (LDH), β-glucuronidase (βG), tartrate resistant acid phosphatase (TRAP), acid phosphatase (ACP) and down regulation in cathepsin B (Cb). Site specificity is shown by ALP, TRAP, AST, LDH, MMP9 with levels at compression site increasing earlier and in higher quantities compared with tension site. ALP levels are higher at tension site only in retention. A positive correlation of LDH, ALP and AST is also observed with increasing orthodontic force magnitude.

Conclusions:

A strong evidence of variation in enzymes (ALP, AST, ACP TRAP, LDH, MMPs, Cb) in GCF is found in association with different magnitude, stages and sites of orthodontic force application.

The effect of naproxen patches on relieving orthodontic pain by evaluation of VAS and IL-1β inflammatory factor: a split-mouth study

Introduction:

Pain related to orthodontic tooth movement is common and cause dissatisfaction and discomfort. Objective: The present study aimed to compare the efficacy of naproxen patches in pain control during orthodontic tooth separation, by means of visual analogue scale (VAS) and interleukin 1β (IL-1β) levels in gingival crevicular fluid (GCF).

Methods:

In this split-mouth triple-blind clinical trial, with 40 patients following separation, 5% naproxen or placebo patches were randomly placed on the upper right or left first molars every 8 hours. Pain intensity scores were determined after 2 and 6 hours, sleep time, 24 hours, days 2, 3 and 7 by the patients using a 100-mm VAS ruler. IL-1β levels in GCF were evaluated by ELISA at baseline, 1 and 24 hours and 7 days. Paired samples t-tests and two-way repeated measures ANOVA analysis of variance with a significance level of 0.05 were applied.

Results:

A total number of 30 patients (13 males and 17 females) finished the trial. Significant differences were found in pain scores (p< 0.0001) and IL-1β levels (p= 0.047) between naproxen and placebo groups. Lower pain scores were reported for the patients using naproxen patches at all time points, except 1 hour after separation. IL-1β levels were lower for the patients using naproxen patches only 1 hour after separation (p= 0.047). The peak of pain scores and IL-1β levels were calculated at 24 hours.

Conclusion:

In the light of VAS scores and IL-1β levels, naproxen patches reduced the pain caused by separator placement.

TNF-α is responsible for the contribution of stromal cells to osteoclast and odontoclast formation during orthodontic tooth movement

Compressive force during orthodontic tooth movement induces osteoclast formation in vivo. TNF-α plays an important role in mouse osteoclast formation and bone resorption induced by compressive force during orthodontic tooth movement. Stromal cells, macrophages and T cells take part in TNF-α-induced osteoclast formation in vitro. Root resorption caused by odontoclasts is a major clinical problem during orthodontic tooth movement. In this study, we determined the cell type targeted by TNF-α during compressive-force-induced osteoclast and odontoclast formation to elucidate the mechanism of bone and root resorption in vivo. An orthodontic tooth movement mouse model was prepared with a nickel-titanium closed coil spring inserted between the maxillary incisors and the first molar. Using TNF receptor 1- and 2-deficient (KO) mice, we found that osteoclast and odontoclast formation was mediated by TNF-α in orthodontic tooth movement. We generated four types of chimeric mice: wild-type (WT) bone marrow cells transplanted into lethally irradiated WT mice (WT>WT), KO bone marrow cells transplanted into lethally irradiated WT mice (KO>WT), WT bone marrow cells transplanted into lethally irradiated KO mice (WT>KO), and KO marrow cells transplanted into lethally irradiated KO mice (KO>KO). Using anti-CD4 and anti-CD8 antibodies, T cells were eliminated from these mice. We subjected these chimeric mice to orthodontic tooth movement. Orthodontic tooth movement was evaluated and tartrate-resistant acid phosphatase-positive cells along the alveolar bone (osteoclasts) and along the tooth root (odontoclasts) were counted after 12 days of tooth movement. The amount of orthodontic tooth movement, and the number of osteoclasts and odontoclasts on the compression side were significantly lower in WT>KO and KO>KO mice than in WT>WT and KO>WT mice. According to these results, we concluded that TNF-α-responsive stromal cells are important for osteoclast and odontoclast formation during orthodontic tooth movement.

Assessment of salivary interleukin-1β (IL-1β), prostaglandin E2 (PGE2) levels and pain intensity in children and adults during initial orthodontic treatment

OBJECTIVES

To investigate pain intensity, interleukin-1β and prostaglandin E₂ values in saliva during initial orthodontic treatment among varying age groups and their correlation between these mediators.

MATERIALS AND METHODS

Twenty healthy patients distributed equally in age and gender groups were chosen. Unstimulated saliva was collected before the placement of orthodontic fixed appliance (T₀), 1 hour after the placement of the appliance with 0.014" nickel titanium archwire (T₁), 1 month after the first visit (T₂), and 1 hour after the placement of 0.016" nickel titanium archwire (T₃). The saliva samples were then analyzed for prostaglandin E₂ and interleukin-1β using enzyme-linked immunosorbent assay. Pain intensity was measured using a numerical rating scale.

RESULTS

Prostaglandin E₂ and interleukin-1β levels had increased at T₁ followed by a drop at T₂ and a subsequent increase at T₃. The prostaglandin E₂ and interleukin-1β levels were higher in adults than children. There was an insignificant correlation between the interleukin-1β and prostaglandin E₂ changes in all the patients. No significant differences were seen in pain scores between adults and children. Insignificant correlation was seen between pain scores and prostaglandin E₂ and interleukin-1β.

CONCLUSION

Prostaglandin E₂ and interleukin-1β can be detected in saliva and are increased in during the initial orthodontic treatment but are higher in adults than children. Pain intensity was not significantly different between adults and children.

Expression of β-catenin and MMP-8 in gingival crevicular fluid and gingival tissue indicates the disease severity of patients with chronic periodontitis

The aim of the present study was to investigate the interaction among β-catenin, matrix metalloproteinase-8 (MMP-8) and severity in patients with chronic periodontitis. Both gingival crevicular fluid (GCF) and gingival tissue was collected from 21 healthy control individuals, 21 patients with moderate chronic periodontitis (mCP) and 23 patients with severe chronic periodontitis (sCP). The concentration of MMP-8 in GCF was detected via ELISA and the mRNA levels of β-catenin and MMP-8 in GCF and gingival tissue was detected via reverse transcription-quantitative PCR. The protein levels of β-catenin and MMP-8 in gingival tissue was detected using western blotting and the interaction between β-catenin and MMP-8 in gingival tissue was detected by co-immunoprecipitation. The expression of β-catenin and MMP-8 was significantly higher in the GCF and gingival tissue of patients with chronic periodontitis (mCP and sCP) compared with the control patients. Furthermore, the expression of β-catenin and MMP-8 in GCF and gingival tissue was positively correlated with the clinical attachment level. In addition, a positive interaction was identified between β-catenin and MMP-8, and the expression of β-catenin was positively correlated with the expression of MMP-8 in GCF and gingival tissue. The CGF and gingival tissue expression of β-catenin and MMP-8 may indicate disease severity in patients with chronic periodontitis.

Gasdermin-d Played a Critical Role in the Cyclic Stretch-Induced Inflammatory Reaction in Human Periodontal Ligament Cells

It has been shown that cyclic stretch could induce inflammatory response such as pyroptosis and the release of IL-1β in human periodontal ligament cells, through activating inflammasome and related caspases. Though gasdermin-d (GSDMD) has been reported to be present in some inflammatory diseases and function as a crucial executioner of pyroptosis, the role of GSDMD in the stretch-induced inflammatory response in human periodontal ligament cells (HPDLCs) has not been well clarified. In this study, it was found that GSDMD was activated by cyclic stretch, and its activation affected the pyroptotic rate in HPDLCs, leading to the maturation and secretion of IL-1β and IL-18 ultimately. In addition, GSDMD was found to be regulated by caspase-1 directly. Nevertheless, the exact relationship between inflammasomes and GSDMD in the stretch-induced inflammatory response still needs to be further elucidated.

Effect of TNF-α-Induced Sclerostin on Osteocytes during Orthodontic Tooth Movement

Osteocytes are abundant cells in bone, which contribute to bone maintenance. Osteocytes express receptor activator of nuclear factor kappa-B ligand (RANKL) and regulate osteoclast formation. Orthodontic tooth movement (OTM) occurs by osteoclast resorption of alveolar bone. Osteocyte-derived RANKL is critical in bone resorption during OTM. Additionally, tumor necrosis factor-α (TNF-α) is important in osteoclastogenesis during OTM. Sclerostin has been reported to enhance RANKL expression in the MLO-Y4 osteocyte-like cell line. This study investigated the effect of TNF-α on sclerostin expression in osteocytes during OTM. In vitro analysis of primary osteocytes, which were isolated from DMP1-Topaz mice by sorting the Topaz variant of GFP-positive cells, revealed that SOST mRNA expression was increased when osteocytes were cultured with TNF-α and that RANKL mRNA expression was increased when osteocytes were cultured with sclerostin. Moreover, the number of TRAP-positive cells was increased in osteocytes and osteoclast precursors cocultured with sclerostin. In vivo analysis of mouse calvariae that had been subcutaneously injected with phosphate-buffered saline (PBS) or TNF-α revealed that the number of TRAP-positive cells and the percentage of sclerostin-positive osteocytes were higher in the TNF-α group than in the PBS group. Furthermore, the level of SOST mRNA was increased by TNF-α. As an OTM model, a Ni-Ti closed-coil spring connecting the upper incisors and upper-left first molar was placed to move the first molar to the mesial direction in wild-type (WT) mice and TNF receptor 1- and 2-deficient (TNFRsKO) mice. After 6 days of OTM, the percentage of sclerostin-positive osteocytes on the compression side of the first molar in TNFRsKO mice was lower than that in WT mice. In this study, TNF-α increased sclerostin expression in osteocytes, and sclerostin enhanced RANKL expression in osteocytes. Thus, TNF-α may play an important role in sclerostin expression in osteocytes and enhance osteoclast formation during OTM.

Remote Corticotomy Accelerates Orthodontic Tooth Movement in a Rat Model

Introduction

With an increasing demand for orthodontic treatment for adult patients, orthodontic professionals are constantly seeking novel strategies and technologies that can accelerate tooth movement in order to shorten the treatment period. For instance, in recent years, the influences of different surgical techniques on orthodontic tooth movement in the ipsilateral side of surgery were intensively investigated. Here, we attempt to examine if corticotomy could also affect the rate of tooth movement in the contralateral side of the surgery by using a rodent model.

Materials and Methods

72 eight-week-old Sprague-Dawley rats were randomly divided into three groups as follows: the Control group (orthodontic treatment devices delivered only, no tooth movement), the orthodontic tooth movement (OTM) group (orthodontic treatment devices delivered and orthodontic treatment performed), and the Corticotomy + OTM group (remote corticotomy performed, orthodontic treatment devices delivered, followed by orthodontic treatment). The surgical procedure was conducted on the right side of the maxilla at the time of appliance placement and a force of 60 g was applied between the maxillary left first molar and maxillary incisors using nickel-titanium springs to stimulate OTM. The OTM distance and speed were tracked at 3, 7, 14, and 28 days post-surgery, followed by histological and immunohistochemical assessments.

Results

In comparison with orthodontic treatment only, the contralateral corticotomy significantly accelerated OTM. Furthermore, animals undergoing corticotomy + OTM presented with a greater number of osteoclasts on the compression side, stronger staining of the osteogenic marker on the tension side, and higher expression of an inflammatory marker than the OTM group animals.

Conclusion

Our current study demonstrates that remote corticotomy effectively accelerates alveolar bone remodeling and OTM. The study enriches our understanding of the regional acceleratory phenomenon (RAP) and offers an alternative strategy for accelerating OTM to shorten the orthodontic treatment period.

Evaluation of leptin concentration in Gingival Crevicular Fluid (GCF) during orthodontic tooth movement and its correlation to the rate of tooth movement

OBJECTIVES:

Leptin, a polypeptide which is related to body fat regulation, is also found to have a role in the inflammatory reaction. The aim of this study is to assess the concentration of leptin in Gingival Crevicular Fluid (GCF) during orthodontic force application and to correlate its concentration to rate of tooth movement.

METHODS:

Twenty orthodontic patients (10 males and 10 females) were selected for the study. Leptin concentration was measured at T0, before force application; T1, one hour after force application; T2, one day after force application; T3, one week after force application; T4, one month after force application. GCF was collected using filter paper strips from the distal aspect of gingival sulcus of the right maxillary canine distalized by an active lace-backs of tooth movement was measured on dental casts, before and one month after force application. One-way ANOVA with Bonferroni correction and Pearson's correlation test were used to analyze the data.

RESULTS:

The mean GCF leptin concentration increased from T0 to T1, rose to a peak at T2, then declined to a minimum value at T3 and then increased to a value at T4, closer to the base line value (T0), and it was statistically significant (P < 0.05). There was positive correlation of the overall mean leptin concentration to rate of tooth movement (correlation coefficient = 0.634).

CONCLUSION:

There was a biphasic change in GCF leptin concentration during one cycle of orthodontic force application. There was a positive correlation between the GCF leptin concentration and rate of tooth movement.

Influence of low-level laser (LLL) on interleukin 6 (IL-6) levels in gingival crevicular fluid (GCF) during orthodontic tooth movement of periodontally affected rabbits

AIM

To evaluate the effects of LLL on IL-6 levels in the GCF and the Probing Pocket Depth measurements (PPD) during orthodontic tooth movement in periodontally affected rabbits.

METHODS

Twenty-four rabbits were divided into 3 groups: Group 1(G1), healthy rabbits with orthodontic movement, Group 2(G2) periodontally affected rabbits and orthodontic movement, Group 3(G3) periodontally affected rabbits with orthodontic movement and LLL therapy. A 0.014 stainless steel spring was inserted in the upper central incisors to produce 60gm force. Laser CAT 500 was applied for 3min/day for 2 weeks. PPD measurements were obtained at base line and after 14 days with electronic periodontal probe.

RESULTS

IL-6 levels increased gradually after application of orthodontic force, afterwards the 8^th day, a significant difference in the Il-6 levels between G1 vs. G2 and G2 vs. G3 was observed. PPD measurements showed significant difference between the three groups at base line and after 14 days.

CLINICAL SIGNIFICANCE

LLL application can enhance periodontal ligament regeneration and decrease the periodontal tissue destruction through suppression of IL-6 levels.

Effects of the cathepsin K inhibitor with mineral trioxide aggregate cements on osteoclastic activity

Objectives

Root resorption is an unexpected complication after replantation procedures. Combining anti-osteoclastic medicaments with retrograde root filling materials may avert this resorptive activity. The purpose of this study was to assess effects of a cathepsin K inhibitor with calcium silicate-based cements on osteoclastic activity.

Methods

MC3T3-E1 cells were cultured for biocompatibility analyses. RAW 264.7 cells were cultured in the presence of the receptor activator of nuclear factor-kappa B and lipopolysaccharide, followed by treatment with Biodentine (BIOD) or ProRoot MTA with or without medicaments (Odanacatib [ODN], a cathepsin inhibitor and alendronate, a bisphosphonate). After drug treatment, the cell counting kit-8 assay and Alizarin red staining were performed to evaluate biocompatibility in MC3T3-E1 cells. Reverse-transcription polymerase chain reaction, tartrate-resistant acid phosphatase (TRAP) staining and enzyme-linked immunosorbent assays were performed in RAW 264.7 cells to determine the expression levels of inflammatory cytokines, interleukin (IL)-1β, IL-6, tumor necrosis factor-α (TNF-α) and prostaglandin E2 (PGE2). Data were analyzed by one-way analysis of variance and Tukey's post hoc test (p < 0.05).

Results

Biocompatibility results showed that there were no significant differences among any of the groups. RAW 264.7 cells treated with BIOD and ODN showed the lowest levels of TNF-α and PGE2. Treatments with BIOD + ODN were more potent suppressors of inflammatory cytokine expression (p < 0.05).

Conclusion

The cathepsin K inhibitor with calcium silicate-based cement inhibits osteoclastic activity. This may have clinical application in preventing inflammatory root resorption in replanted teeth.

Proinflammatory mediators related to orthodontically induced periapical root resorption in rat mandibular molars

Objectives

The early phase of orthodontic tooth movement involves acute inflammatory response that may induce bone resorption. The aim of this study was to localize and quantify cells in the periodontium expressing proinflammatory mediators during orthodontically induced periapical root resorption of the rat mandibular molars.

Materials and methods

The levels of proinflammatory cytokines interleukin-1 (IL-1) α and β, tumor necrosis factor-α (TNF-α), inflammatory enzymes cyclooxygenase (COX) 1 and 2, and their product prostaglandin E2 (PGE2) in the root resorption site were compared to those in the corresponding area of the untreated periodontal ligament (PDL) of physiologically drifting teeth. Continuous heavy orthodontic force was applied to the mandibular first molar for 8 and 15 days while in occlusion to induce root resorption. Frozen sections including root resorption lacunae were analyzed for the activity of non-specific esterase (NSE) and tartrate-resistant acid phosphatase (TRAP) by enzyme histochemistry and for the expression of IL-1α, IL-1β, TNF-α, COX-1, COX-2, and PGE2 by immunohistochemistry.

Results

The active root resorption lacunae had significantly more TRAP-positive multinucleated odontoclasts, whereas the number of NSE-positive cells of the monocyte-macrophage lineage did not differ from that in the control PDL. Several types of periodontal cells exhibited a significant increase in the expression of IL-1α, IL-1β, TNF-α, COX-2, and PGE2 in the root resorption zone, while COX-1 was rarely detected.

Conclusions

These data suggest that proinflammatory mediators expressed in periodontal cells may synergistically promote apical root resorption in response to continuous heavy mechanical force applied to teeth.

Experimental investigation of effects of platelet-rich plasma on early phases of orthodontic tooth movement

INTRODUCTION

The aim of this study was to evaluate the effects of platelet-rich plasma on orthodontic tooth movement in rats.

METHODS

We divided 48 Wistar male albino rats into 3 groups: control group, platelet-rich plasma group, and platelet-poor plasma group. The rats in all study groups had orthodontic tooth movement of their maxillary right first molars. Either platelet-rich plasma or platelet-poor plasma was injected into the animals in the platelet-rich plasma and platelet-poor plasma groups, respectively; the rats in the control group had no injection. Distances between the maxillary molar and incisor were measured on days 0, 1, 3, 7, and 14. Active osteoblast numbers in tension sites and osteoclast numbers in compression sites were examined histologically. Immunohistochemical evaluations of tartrate-resistant acid phosphatase (TRAP), transforming growth factor-β (TGF-β), and alkaline phosphatase (ALP) expressions were also performed.

RESULTS

The rats in the platelet-rich plasma group showed less tooth movement than those in the control group at day 3. At day 14, maximum tooth movement was observed in all groups. However, there was no statistical significance among the groups at day 14. In terms of osteoclast and osteoblast cells, no significant differences were observed in any group or at any time. Also, there were no significant differences in TRAP, ALP, and TGF-β expressions in the groups.

CONCLUSIONS

The application of platelet-rich plasma was not beneficial as an adjunct to orthodontic treatment.

Periodontically accelerated orthodontic tooth movement: A narrative review

Adult orthodontics has gained widespread acceptance recently with the introduction of more esthetic options for the patient. The major deterrent that remains is the prolonged treatment time associated with comprehensive orthodontic treatment. The objective of this paper is to present a review of techniques, which could be employed by the orthodontist in conjunction with a periodontist to enhance the rate of orthodontic tooth movement. The biological rationale and clinical manipulation have been discussed with a brief review of the current literature about these techniques. The interdisciplinary approach involving the orthodontist and the periodontist can benefit the patient by affording them with reduced treatment time.