Vibration enhances PGE2 , IL-6, and IL-8 expression in compressed hPDL cells via cyclooxygenase pathway

The Mechanosensitive PIEZO1 Channel Contributes to the Reaction of RAW264.7 Macrophages to Mechanical Strain

The mechanosensitive channel 'piezo type mechanosensitive ion channel component 1' (PIEZO1) plays a regulatory role in the response of periodontal ligament fibroblasts (PDLFs) to the mechanical strain that occurs during orthodontic tooth movement. In addition to PDLFs, immune cells such as macrophages are also exposed to mechanical stimuli. Macrophages respond to mechanical strain with increased expression of inflammatory mediators. The role of PIEZO1 in this response remains elusive. To investigate the effect of PIEZO1 activation, RAW264.7 macrophages were stimulated with the PIEZO1 activator YODA1 without concurrent application of pressure. To further examine the specific role of PIEZO1 during mechanical strain, RAW264.7 macrophages were exposed to mechanical strain without and with simultaneous inhibition of PIEZO1 either by chemical inhibition (GsMTx4) or siRNA silencing. The expression of genes and proteins involved in orthodontic tooth movement was examined by quantitative PCR, western blot, and enzyme-linked immunosorbent assay (ELISA). Activation of PIEZO1 by YODA1 or mechanical strain increased the expression of inflammatory cytokines and osteoprotegerin (Opg), which is critically involved in bone remodeling processes. Conversely, inhibition of the PIEZO1 channel attenuates the effects of mechanical stress. In conclusion, our data demonstrate that the PIEZO1 channel is a major contributor to the response of macrophages to mechanical strain encountered during orthodontic tooth movement and affects the expression of inflammatory and bone remodeling factors.

Effective mechanical vibration frequency in canine tooth movement acceleration: a systematic review and network meta-analysis of randomized controlled trial studies

OBJECTIVE

This study aims to evaluate the effectiveness of various supplementary vibrational frequencies with orthodontic force on the rate of canine movement.

MATERIALS AND METHODS

A literature search was conducted in PubMed, Embase, Cochrane, Scopus, ClinicalTrials.gov, and Google Scholar, with the final search on February 17, 2025. Randomized controlled trials (RCTs) involving participants undergoing orthodontic treatment with upper first premolar extraction, assessed the effect of different vibration frequencies on canine movement rate were included. Study quality was assessed using the Risk of Bias (RoB) 2. A random-effects model (DerSimonian and Laird method) for pairwise meta-analysis (PMA) and a frequentist-based network meta-analysis (NMA) estimated relative effects, with mean difference (MD) and 95% confidence interval (CI) calculated for all comparisons. The certainty of evidence was assessed using the Confidence in Network Meta-Analysis tool.

RESULTS

Ten RCTs examined the effects of five vibration frequencies. The RoB ranged from low to high. The PMA found vibrations significantly increased tooth movement (MD = 0.084 mm, 95% CI [0.004, 0.164]). Conversely, NMA showed no significant differences across all comparisons. The Surface Under the Cumulative Ranking Curve ranked 125 Hz as the most effective, followed by 100, 60, 30, and 0 Hz. The confidence in evidence ranged from low to moderate.

CONCLUSIONS

The use of supplementary vibration in conjunction with orthodontic force statistically effectively accelerates tooth movement, with higher frequencies showing a tendency to yield better acceleration results.

CLINICAL RELEVANCE

While vibration therapy demonstrated a statistically significant effect on canine movement, the magnitude of this effect was not sufficient to be considered clinically significant for orthodontic treatment. Further research is required to optimize the effectiveness.

The age-related effects on orthodontic tooth movement and the surrounding periodontal environment

Orthodontic treatment in adults is often related to longer treatment time as well as higher periodontal risks compared to adolescents. The aim of this review is to explore the influence of age-related chages on orthodontic tooth movement (OTM) from macro and micro perspectives. Adults tend to show slower tooth movement speed compared to adolescence, especially during the early phase. Under orthodontic forces, the biological responses of the periodontal ligament (PDL) and alveolar bone is different between adult and adolescents. The adult PDL shows extended disorganization time, increased cell senescence, less cell signaling and a more inflammatory microenvironment than the adolescent PDL. In addition, the blood vessel surface area is reduced during the late movement phase, and fiber elasticity decreases. At the same time, adult alveolar bone shows a higher density, as well as a reduced osteoblast and osteoclast activation, under orthodontic forces. The local cytokine expression also differs between adults and adolescents. Side-effects, such as excessive root resorption, greater orthodontic pain, and reduced pulpal blood flow, also occur more frequently in adults than in adolescents.

Effect of compressive force combined with vibration on CCL2 and CCL5 in human periodontal ligament cells

Purpose

To investigate the effect of compressive force combined with vibration on expression of CC-chemokine ligand 2 (CCL2) and 5 (CCL5) in human periodontal ligament (hPDL) cells.

Methods

Human PDL cells were cultured and assigned into four groups: control (Con), compressive force 2.0 g/cm2 for 24 h and 48 h (C), vibration 0.3 g 30 Hz for 20 min every 24 h (V), and compressive force combined with vibration (VC). At 24 h and 48 h, mRNA and protein levels of CCL2 and CCL5 were examined by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and enzyme-linked immunosorbent assay (ELISA), respectively.

Results

At 24 h and 48 h, CCL2 mRNA and protein levels in C and VC were significantly higher than Con. At 24 h, VC showed significantly higher CCL2 mRNA expression than C. However, there was no significant difference between CCL2 protein in C and VC at both time points. At 24 h and 48 h, CCL5 mRNA expression was significantly down-regulated in V and VC, whereas CCL5 protein was undetectable in all groups.

Conclusions

Application of compressive force combined with vibration resulted in the upregulation of CCL2 mRNA and protein levels, whereas CCL5 mRNA expression was down-regulated.

The gingival crevicular fluid biomarkers with micropulse vibration device: A pilot study

Purpose

The aim of this study is to investigate the impact of vibration stimulation on gingival crevicular fluid biomarkers and orthodontic tooth movement.

Methods

Forty patients were randomly assigned to receive therapy with an intraoral vibration device (n = 20, AcceleDent®) or no treatment (n = 20) at a university orthodontic clinic. The quantity of fluid in the gingival sulcus, biomarkers of each fluid in the gingival sulcus, and orthodontic tooth movement were analyzed at three-time intervals (T1, T2, T3) before and after therapy (T0).

Results

The results showed that vibration treatment led to higher levels of osteoclast biomarkers (RNAKL, RANKL/OPG) and inflammatory biomarkers (TNF-, IL-11, IL-18) compared to the control group. Additionally, vibration treatment at T1, T2, and T3 significantly improved tooth mobility and GCF volume. The gingival crevicular fluid biomarker levels of the T0, T1, and T2 vibration groups, as well as IL-11, IL-18, TGF-1, and TNF-α vibration groups, were significantly higher than those of the control group at different time points.

Conclusion

vibration therapy was found to be closely associated with bone-breaking cells and inflammatory factor levels.

The importance of mechanosensitive cell mediated prostaglandin and nitric oxide synthesis in the pathogenesis of apical periodontitis: comparative with chronic periodontitis

OBJECTIVES

Mechano-sensitive odontoblast cells, which sense mechanical loading and various stresses in the tooth structure, synthesize early signaling molecules such as prostaglandin E2 (PGE2) and nitric oxide (NO) as an adaptive response. It is thought that these synthesized molecules can be used for the diagnosis and treatment of periodontal and periapical diseases. The aim of this study was to investigate the relationship between the severity of apical periodontitis (AP) and chronic periodontitis (CP) and serum (s) TNF-α, IL-10, PGE2 and NO levels, as well as PGE2 and NO levels in gingival crevicular fluid (GCF) samples.

MATERIALS & METHODS

A total of 185 subjects were divided into three categories: AP group (n = 85), CP group (n = 50) and healthy control group (n = 50). The AP group was divided into 3 subgroups according to abscess scoring (AS-PAI 1, 2 and 3) based on the periapical index. The CP group was divided into 4 subgroups according to the periodontitis staging system (PSS1, 2,3 and 4). After recording the demographic and clinical characteristics of all participants, serum (s) and gingival crevicular fluid (GCF) samples were taken. TNF-α, IL-10, PGE2 and NO levels were measured in these samples.

RESULTS

Unlike serum measurements (sTNF-α, sIL-10, sNO and sPGE2), GCF-NO and GCF-PGE levels of the AP group were significantly higher than the control group in relation to abscess formation (54.4 ± 56.3 vs. 22.5 ± 12.6 µmol/mL, p < 0.001 and 100 ± 98 vs. 41 ± 28 ng/L, p < 0.001, respectively). Confirming this, the GCF-NO and GCF-PGE levels of the AS-PAI 1 group, in which abscesses have not yet formed, were found to be lower than those in AS-PAI 2 and 3, which are characterized by abscess formation [(16.7(3.7-117.8), 32.9(11.8-212.8) and 36.9(4.3-251.6) µmol/mL, p = 0,0131; 46.0(31.4-120.0), 69.6(40.3-424.2) and 74.4(32.1-471.0) ng/L, p = 0,0020, respectively]. Consistent with the increase in PSS, the levels of sTNF [29.8 (8.2-105.5) vs. 16.7(6.3-37.9) pg/mL, p < 0.001], sIL-10 [542(106-1326) vs. 190(69-411) pg/mL, p < 0.001], sNO [182.1(36.3-437) vs. 57.0(15.9-196) µmol/mL, p < 0.001], sPGE2 [344(82-1298) vs. 100(35-1178) ng/L, p < 0.001], GCF-NO [58.9 ± 33.6 vs. 22.5 ± 12.6 ng/L, p < 0.001] and GCF-PGE2 [ 99(37-365) vs. 30(13-119), p < 0.001] in the CP group were higher than the control group. Comparison ROC analysis revealed that the GCF-PGE2 test had the best diagnostic value for both AP and CP (sensitivity: 94.1 and 88.0; specificity: 64.0 and 78.0, respectively; p < 0.001).

CONCLUSIONS

GCF-PE2 and GCF-NO have high diagnostic value in the determination of AP and CP, and can be selected as targets to guide treatment. In addition, the measurements of PGE2 and NO in GCF can be used as an important predictor of pulpal necrosis leading to abscess in patients with AP.

CLINICAL RELEVANCE

In this article, it is reported that syntheses of early signaling molecules such as PGE2 and NO can be used for the diagnosis and treatment target of periapical and periodontal infections.

Static magnetic field-induced IL-6 secretion in periodontal ligament stem cells accelerates orthodontic tooth movement

Static magnetic field (SMF) promoting bone tissue remodeling is a potential non-invasive therapy technique to accelerate orthodontic tooth movement (OTM). The periodontal ligament stem cells (PDLSCs), which are mechanosensitive cells, are essential for force-induced bone remodeling and OTM. However, whether and how the PDLSCs influence the process of inflammatory bone remodeling under mechanical force stimuli in the presence of SMFs remains unclear. In this study, we found that local SMF stimulation significantly enhanced the OTM distance and induced osteoclastogenesis on the compression side of a rat model of OTM. Further experiments with macrophages cultured with supernatants from force-loaded PDLSCs exposed to an SMF showed enhanced osteoclast formation. RNA-seq analysis showed that interleukin-6 (IL-6) was elevated in force-loaded PDLSCs exposed to SMFs. IL-6 expression was also elevated on the pressure side of a rat OTM model with an SMF. The OTM distance induced by an SMF was significantly decreased after injection of the IL-6 inhibitor tocilizumab. These results imply that SMF promotes osteoclastogenesis by inducing force-loaded PDLSCs to secrete the inflammatory cytokine IL-6, which accelerates OTM. This will help to reveal the mechanism of SMF accelerates tooth movement and should be evaluated for application in periodontitis patients.

Current perspectives of residual ridge resorption: Pathological activation of oral barrier osteoclasts

PURPOSE

Tooth extraction is a last resort treatment for resolving pathological complications of dentition induced by infection and injury. Although the extraction wound generally heals uneventfully, resulting in the formation of an edentulous residual ridge, some patients experience long-term and severe residual ridge reduction. The objective of this review was to provide a contemporary understanding of the molecular and cellular mechanisms that may potentially cause edentulous jawbone resorption.

STUDY SELECTION

Clinical, in vivo, and in vitro studies related to the characterization of and cellular and molecular mechanisms leading to residual ridge resorption.

RESULTS

The alveolar processes of the maxillary and mandibular bones uniquely juxtapose the gingival tissue. The gingival oral mucosa is an active barrier tissue that maintains homeostasis of the internal organs through its unique barrier immunity. Tooth extraction not only generates a bony socket but also injures oral barrier tissue. In response to wounding, the alveolar bone socket initiates regeneration and remodeling through coupled bone formation and osteoclastic resorption. Osteoclasts are also found on the external surface of the alveolar bone, interfacing the oral barrier tissue. Osteoclasts in the oral barrier region are not coupled with osteoblastic bone formation and often remain active long after the completion of wound healing, leading to a net decrease in the alveolar bone structure.

CONCLUSIONS

The novel concept of oral barrier osteoclasts may provide important clues for future clinical strategies to maintain residual ridges for successful prosthodontic and restorative therapies.

Light orthodontic force with high-frequency vibration accelerates tooth movement with minimal root resorption in rats

OBJECTIVES

To determine and compare the effects of high-frequency mechanical vibration (HFV) with light force and optimal force on the tooth movement and root resorption in rat model.

MATERIALS AND METHODS

Seventy-two sites in 36 male Wistar rats were randomly assigned using a split-mouth design to control (no force/no vibration) or experimental groups: HFV (125 Hz), light force (5 g), optimal force (10 g), light force with HFV, and optimal force with HFV for 14 and 21 days. The amount of tooth movement, 3D root volume, and root resorption area were assessed by micro-computed tomography and histomorphometric analysis.

RESULTS

Adjunction of HFV with light force significantly increased the amount of tooth movement by 1.8-fold (p = 0.01) and 2.0-fold (p = 0.01) at days 14 and 21 respectively. The HFV combined with optimal force significantly increased the amount of tooth movement by 2.1-fold (p = 0.01) and 2.2-fold (p = 0.01) at days 14 and 21 respectively. The root volume in control (distobuccal root (DB): 0.60 ± 0.19 mm³, distopalatal root (DPa): 0.60 ± 0.07 mm³) and HFV (DB: 0.60 ± 0.08 mm³, DPa: 0.59 ± 0.11 mm³) were not different from the other experimental group (range from 0.44 ± 0.05 to 0.60 ± 0.1 mm³) with the lowest volume in optimal force group.

CONCLUSIONS

Adjunction of HFV with orthodontic force significantly increased tooth movement without causing root resorption.

CLINICAL RELEVANCE

Using light force with HFV could help to identify alternative treatment option to reduce the risk of root resorption.

Human Interleukin-1β Profile and Self-Reported Pain Monitoring Using Clear Aligners with or without Acceleration Techniques: A Case Report and Investigational Study

INTRODUCTION

There is a growing demand for more aesthetic, comfortable, and faster orthodontic treatments, and clear aligners emerged as a solution to fulfill this need. However, the effectiveness of clear aligners to treat complex malocclusions is yet contentious. The use of acceleration methods could improve the efficacy of clear aligners by stimulating cells' mechanobiology through numerous pathways, but this hypothesis is still poorly explored.

OBJECTIVE

We aimed to monitor the release profile of an inflammatory marker-the interleukin-1β-and to evaluate its relationship with self-reported pain scores with and without the use of acceleration techniques during an orthodontic treatment requiring difficult tooth movements with clear aligners. Case Report. Here, we report a case of a 46-year-old female patient who presented functional and aesthetic complaints. Intraoral examination revealed a diminished overjet and overbite, rotation of teeth 45 and 24, absence of teeth 25, 35, and 36, buccolingual dislocation of tooth 21, a tendency to a Class III malocclusion, and a 2 mm left deviation of the lower midline. This study is divided into three stimulation phases: no stimulation, mechanical vibration stimulation, and photobiomodulation. Interleukin-1β levels in gingival crevicular fluid samples from the pressure side of six selected teeth were evaluated at four time points after the orthodontic treatment onset. Pain monitoring in those teeth was performed using a visual analogue scale at the same time points.

RESULTS

Interleukin-1β protein production peaked 24 h after treatment onset. Complex movements were associated with increased self-reported pain.

CONCLUSION

Clear aligners show limitations in solving complex tooth movements, even when combined with acceleration. The development of customized and programmable stimulation microdevices integrated into "smart aligners," which could be designed to specifically stimulate the direction of movement and stimulation parameters and could constitute a solution to optimize the orthodontic tooth movement with clear aligners.

Effects of compressive stress combined with mechanical vibration on osteoclastogenesis in RAW 264.7 cells

OBJECTIVES

To investigate the effects of compressive force and/or mechanical vibration on NFATc1, DCSTAMP, and CTSK (cathepsin K) gene expression and the number of tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells in RAW 264.7 cells, a murine osteoclastic-like cell line.

MATERIALS AND METHODS

RAW 264.7 cells were subjected to mechanical vibration, compressive force, or compressive force combined with vibration. Cell viability and the numbers of TRAP-positive multinucleated cells were evaluated. NFATc1, DCSTAMP, and CTSK gene expressions were analyzed using real-time quantitative reverse transcription polymerase chain reaction.

RESULTS

Compressive force combined with mechanical vibration significantly increased the numbers of TRAP-positive multinucleated cells but did not significantly affect cell viability. In addition, compressive force combined with mechanical vibration significantly increased NFATc1, DCSTAMP, and CTSK mRNA expression compared with compressive force or vibration alone.

CONCLUSIONS

Compressive force combined with mechanical vibration induces osteoclastogenesis and upregulates NFATc1, DCSTAMP, and CTSK gene expression in RAW 264.7 cells. These results provide more insight into the mechanisms by which vibratory force accelerates orthodontic tooth movement.

Biomechanical and biological responses of periodontium in orthodontic tooth movement: up-date in a new decade

Nowadays, orthodontic treatment has become increasingly popular. However, the biological mechanisms of orthodontic tooth movement (OTM) have not been fully elucidated. We were aiming to summarize the evidences regarding the mechanisms of OTM. Firstly, we introduced the research models as a basis for further discussion of mechanisms. Secondly, we proposed a new hypothesis regarding the primary roles of periodontal ligament cells (PDLCs) and osteocytes involved in OTM mechanisms and summarized the biomechanical and biological responses of the periodontium in OTM through four steps, basically in OTM temporal sequences, as follows: (1) Extracellular mechanobiology of periodontium: biological, mechanical, and material changes of acellular components in periodontium under orthodontic forces were introduced. (2) Cell strain: the sensing, transduction, and regulation of mechanical stimuli in PDLCs and osteocytes. (3) Cell activation and differentiation: the activation and differentiation mechanisms of osteoblast and osteoclast, the force-induced sterile inflammation, and the communication networks consisting of sensors and effectors. (4) Tissue remodeling: the remodeling of bone and periodontal ligament (PDL) in the compression side and tension side responding to mechanical stimuli and root resorption. Lastly, we talked about the clinical implications of the updated OTM mechanisms, regarding optimal orthodontic force (OOF), acceleration of OTM, and prevention of root resorption.

Impact of Vibration on the Levels of Biomarkers: A Systematic Review

Introduction:

The objective of this systematic review is to assess the effect of vibrational force on biomarkers for orthodontic tooth movement.

Methods:

An electronic search was conducted for relevant studies (up to December 31, 2020) on the following databases: Pubmed, Google scholar, Web of Science, Cochrane Library, Wiley Library, and ProQuest Dissertation Abstracts and Thesis database. Hand searching of selected orthodontic journals was also undertaken. The selected studies were assessed for the risk of bias in Cochrane collaboration risk of bias tool. The “traffic plot” and “weighted plot” risk of bias distribution are designed in the RoB 2 tool. The 2 authors extracted the data and analyzed it.

Results:

Six studies fulfilled the inclusion criteria. The risks of biases were high for 4, low and some concern for other 2 studies. The biomarkers, medium, device, frequency and duration of device, as well as other data were extracted. The outcomes of the studies were found to be heterogenous.

Conclusion:

One study showed highly statistically significant levels of IL-1 beta with <.001. Rate of tooth movement was correlated with levels of released biomarkers under the influence of vibrational force in 3 studies, but it was found to be significant only in 1 study. It was further observed that vibration does not have any significant reduction in pain and discomfort.

CXCL5, CXCL8, and CXCL10 regulation by bacteria and mechanical forces in periodontium

OBJECTIVE

The aim of the present study was to evaluate the expressions of CXCL5, CXCL8, and CXCL10 in periodontal cells and tissues in response to microbial signals and/or biomechanical forces.

METHODS

Human gingival biopsies from inflamed and healthy sites were used to examine the chemokine expressions and protein levels by real-time PCR and immunohistochemistry. The chemokines were also investigated in gingival biopsies from rats submitted to experimental periodontitis and/or tooth movement. Furthermore, chemokine levels were determined in human periodontal fibroblasts stimulated by the periodontopathogen Fusobacterium nucleatum and/or constant tensile forces (CTS) by real-time PCR and ELISA. Additionally, gene expressions were evaluated in periodontal fibroblasts exposed to F. nucleatum and/or CTS in the presence and absence of a MAPK inhibitor by real-time PCR.

RESULTS

Increased CXCL5, CXCL8, and CXCL10 levels were observed in human and rat gingiva from sites of inflammation as compared with periodontal health. The rat experimental periodontitis caused a significant (p<0.05) increase in alveolar bone resorption, which was further enhanced when combined with tooth movement. In vitro, F. nucleatum caused a significant upregulation of CXCL5, CXCL8, and CXCL10 at 1 day. Once the cells were exposed simultaneously to F. nucleatum and CTS, the chemokines regulation was significantly enhanced. The transcriptional findings were also observed at protein level. Pre-incubation with the MEK1/2 inhibitor significantly (p<0.05) inhibited the stimulatory actions of F. nucleatum either alone or in combination with CTS on the expression levels of CXCL5, CXCL8, and CXCL10 at 1d.

CONCLUSIONS

Our data provide original evidence that biomechanical strain further increases the stimulatory actions of periodontal bacteria on the expressions of these chemokines. Therefore, biomechanical loading in combination with periodontal infection may lead to stronger recruitment of immunoinflammatory cells to the periodontium, which might result in an aggravation of periodontal inflammation and destruction.

Mechanical force inhibited hPDLSCs proliferation with the downregulation of MIR31HG via DNA methylation

OBJECTIVE

This study aimed to investigate how mechanical force affects the proliferation of human periodontal ligament stem cells (hPDLSCs).

METHODS

CCK-8 assays and staining of ki67 were performed to evaluate hPDLSCs proliferation. qRT-PCR, ELISA, or Western blot analysis were used to measure the expression levels of interleukin (IL)-6, miR-31 host gene (MIR31HG), DNA methyltransferase 1 (DNMT1), and DNA methyltransferase 3B (DNMT3B). Dual-luciferase reporter assays and chromatin immunoprecipitation (ChIP) assays were conducted to determine whether MIR31HG was targeted by DNMT1 and DNMT3B. MassARRAY mass spectrometry was used to quantify DNA methylation levels of the MIR31HG promoter.

RESULTS

Mechanical force inhibited hPDLSCs proliferation with the downregulation of MIR31HG and upregulation of IL-6, DNMT1 and DNMT3B. Knockdown of MIR31HG suppressed hPDLSCs proliferation, and knockdown of DNMT1 or DNMT3B reversed mechanical force-induced downregulation of MIR31HG. Dual-luciferase and ChIP assays revealed DNMT1 and DNMT3B bound MIR31HG promoter in the region 1,015 bp upstream of the transcriptional start site. Treatment with 5'-aca-2'-deoxycytidine downregulated DNA methylation level in MIR31HG gene promoter, while mechanical force promoted the methylation of MIR31HG gene promoter.

CONCLUSIONS

These findings elucidated how mechanical force affects proliferation via MIR31HG in hPDLSCs, providing clues for possible MIR31HG-based orthodontic therapeutic approaches.

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.

Inhibition of Porphyromonas gulae and periodontal disease in dogs by a combination of clindamycin and interferon alpha

Porphyromonas gulae is a major periodontal pathogen in dogs, which can be transmitted to their owners. A major virulence factor of P. gulae consists of a 41-kDa filamentous appendage (FimA) on the cell surface, which is classified into three genotypes: A, B, and C. Thus far, inhibition of periodontal disease in dogs remains difficult. The present study assessed the inhibitory effects of a combination of clindamycin and interferon alpha (IFN-α) formulation against P. gulae and periodontal disease. Growth of P. gulae was significantly inhibited by clindamycin; this inhibition had a greater effect on type C P. gulae than on type A and B isolates. In contrast, the IFN-α formulation inhibited the expression of IL-1β and COX-2 elicited by type A and B isolates, but not that elicited by type C isolates. Furthermore, periodontal recovery was promoted by the administration of both clindamycin and IFN-α formulation to dogs undergoing periodontal treatment; moreover, this combined treatment reduced the number of FimA genotypes in oral specimens from treated dogs. These results suggest that a combination of clindamycin and IFN-α formulation inhibit P. gulae virulence and thus may be effective for the prevention of periodontal disease induced by P. gulae.

Vibration activates the actin/NF-κB axis and upregulates IL-6 and IL-8 expression in human periodontal ligament cells

We previously reported that mechanical vibration-induced proinflammatory cytokines, interleukin-6 (IL-6) and IL-8, expression in human periodontal ligament (hPDL) cells, however, the underlying mechanism remained unclear. Mechanical stimuli are able to activate cellular responses by inducing the activation of several signaling pathways including cytoskeletal changes and inflammation. The actin cytoskeleton is a highly dynamic network and plays many important roles in intracellular events. Here, we aimed to investigate the involvement of a pivotal mediator of inflammatory responses, nuclear factor-κB (NF-κB), and actin polymerization in vibration-induced upregulation of IL-6 and IL-8 expression in hPDL cells. hPDL cells were pretreated with the NF-κB inhibitor BAY 11-7082 or cytochalasin D, respectively, before exposure to vibration. IL-6 and IL-8 messenger RNA (mRNA) and protein expression were quantified by quantitative polymerase chain reaction and enzyme-linked immunosorbent assays, respectively. Subcellular localization of the NF-κB p65 subunit was visualized by immunofluorescent staining. We found an increase in NF-κB nuclear translocation in vibrated cells compared with control cells. Pretreatment with BAY 11-7082 significantly inhibited vibration-induced IL-6 and IL-8 mRNA and protein expression in hPDL cells. Moreover, pretreatment with cytochalasin D inhibited NF-κB nuclear translocation and attenuated upregulation of IL-6 and IL-8 mRNA and protein in vibrated cells. Therefore, modulation of actin cytoskeletal polymerization in response to vibration may activate the NF-κB signaling pathway and subsequently upregulate IL-6 and IL-8 expression in hPDL cells.

Interleukin 6 decreases nociceptor expression of the potassium channel KV1.4 in a rat model of hand-arm vibration syndrome

Chronic muscle pain is a prominent symptom of the hand-arm vibration syndrome (HAVS), an occupational disease induced by exposure to vibrating power tools, but the underlying mechanism remains unknown. We evaluated the hypothesis that vibration induces an interleukin 6 (IL-6)-mediated downregulation of the potassium voltage-gated channel subfamily A member 4 (KV1.4) in nociceptors leading to muscle pain. Adult male rats were submitted to a protocol of mechanical vibration of the right hind limb. Twenty-four hours after vibration, muscle hyperalgesia was observed, concomitant to increased levels of IL-6 in the gastrocnemius muscle and decreased expression of KV1.4 in the dorsal root ganglia. Local injection of neutralizing antibodies against IL-6 attenuated the muscle hyperalgesia induced by vibration, whereas antisense knockdown of this channel in the dorsal root ganglia mimicked the muscle hyperalgesia observed in the model of HAVS. Finally, knockdown of the IL-6 receptor signaling subunit glycoprotein 130 (gp130) attenuated both vibration-induced muscle hyperalgesia and downregulation of KV1.4. These results support the hypothesis that IL-6 plays a central role in the induction of muscle pain in HAVS. This likely occurs through intracellular signaling downstream to the IL-6 receptor subunit gp130, which decreases the expression of KV1.4 in nociceptors.

Low magnitude high frequency vibration induces RANKL via cyclooxygenase pathway in human periodontal ligament cells in vitro

Objective

This study aimed to examine the effects of PGE2 on RANKL expression in response to vibration and vibration in combination with compressive stress and characterise this transduction pathway in periodontal ligament (PDL) cells.

Methods

Cultured human PDL cells obtained from extracted premolar teeth (from six individuals) were subjected to three cycles of vibration (0.3 g, 30 Hz for 20 min every 24 h; V), compressive stress (1.5 g/cm², 48 h; C) or vibration in combination with compressive stress (VC). To investigate whether the expression of RANKL and PGE2 was COX-dependent, PDL cells were treated with indomethacin prior to the onset of mechanical stimulation. RANKL and OPG expressions were examined by quantitative real-time polymerase chain reaction (qPCR). Quantification of PGE2, soluble RANKL (sRANKL) and OPG productions were measured using enzyme-linked immunosorbent assay (ELISAs).

Results

All mechanical stresses (V, C and VC) significantly increased PGE2 and RANKL. OPG was not affected by vibration, but was downregulated in compressed cells (C and VC). Indomethacin abolished induction of RANKL and downregulated OPG in response to all mechanical stresses.

Conclusion

These results suggest that vibration, compressive stress and vibration in combination with compressive stress induce RANKL expression in human PDL cells by activating the cyclooxygenase pathway.

Effects of two frequencies of vibration on the maxillary canine distalization rate and RANKL and OPG secretion: A randomized controlled trial

OBJECTIVES

To investigate the effects of 30 and 60 Hz vibratory stimulus on canine distalization and RANKL and OPG secretion.

SETTING AND SAMPLE POPULATION

Sixty patients requiring canine distalization at the Orthodontic Clinic, Prince of Songkla University.

MATERIALS AND METHODS

Patients were randomly assigned to 30 Hz vibration (n = 20), 60 Hz vibration (n = 20), or the control group (n = 20). Modified electric toothbrushes were used to apply vibration to the randomly selected canine for 20 min/day by the investigator combined with 60 cN continuous distalization force from day 1 to day 7. RANKL and OPG were analysed before (T1) and 24 hours (T2), 48 hours (T3) and 7 days (T4) after initiation of distalization. From day 8, vibratory devices were used by the subjects at home. Rate of canine distalization (T1 to 3 months after initiation [T5]) was calculated. Kruskal-Wallis tests were used for multiple comparisons (significance level, 0.05).

RESULTS

Canine distalization rate was not different between groups (median; 0.82, 0.87, and 0.83 mm/month for 30, 60 Hz, and control group, respectively; P > 0.05). No within- or between-group differences in RANKL and OPG were observed (P > 0.05), except RANKL on the compression side of the control group was significantly higher at T2, T3 and T4 than T1 (P < 0.001).

CONCLUSION

In the clinic, 30 and 60 Hz vibratory stimulus have no additive effect on rate of canine distalization rate, RANKL and OPG secretion or RANKL/OPG ratio.

The effect of compressive force combined with mechanical vibration on human alveolar bone osteoblasts

Objective

This study aimed to investigate the effects of compressive force combined with mechanical vibration on the expression of pro-inflammatory cytokines that promote osteoclastogenesis and related to orthodontic tooth movement acceleration in human alveolar bone osteoblasts in vitro.

Methods

Osteoblasts were subjected to compressive force (C), mechanical vibration (V), compressive force combined with mechanical vibration (CV), or no force as a control for 12, 24 and 48 h. Interleukin-1 beta (IL-1β), interleukin-6 (IL-6), receptor activator of nuclear factor kappa-Β ligand (RANKL) and osteoprotegerin (OPG) mRNA and protein expression were assessed using quantitative real-time polymerase chain reaction and enzyme-linked immunosorbent assays.

Results

In C and CV groups, IL-1β and IL-6 mRNA and protein expression were significantly higher and OPG mRNA and protein expression were significantly lower than control and V groups. However, the expressions were not different between C and CV groups. RANKL mRNA and protein expression were not different between any groups. While, OPG mRNA and protein expression in V group were significantly higher than control group.

Conclusions

Vibration neither enhanced nor inhibited the expression of IL-1β, IL-6, RANKL and OPG in compressed human alveolar bone osteoblasts.