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

Prevalence and virulence factors of haemolytic Enterococcus faecalis isolated from root filled teeth associated with periradicular lesions: A laboratory investigation in Thailand

AIM

Previous endodontic research has provided limited understanding of the prevalence and roles of haemolytic and non-haemolytic Enterococcus faecalis strains in root filled teeth. This study aimed to determine the prevalence of these strains in root filled teeth with periradicular lesions and investigate their associated virulence factors.

METHODOLOGY

A total of 36 root canal samples were collected from 36 subjects. The prevalence of E. faecalis was determined using culture and PCR methods. Antibiotic susceptibility of haemolytic and non-haemolytic E. faecalis strains was assessed using the broth dilution assay. The cytokine stimulation in periodontal ligament (PDL) cells and neutrophil migration were evaluated using real-time PCR and migration assay, respectively. Cell invasion ability of the strains was assessed using a cell culture model. Additionally, the virulence gene expression of the haemolytic and non-haemolytic strains was investigated using real-time PCR. The Mann-Whitney U and Spearman's ρ tests were used to examine the significant difference between the two strains and to analyse the correlation between phenotype and gene expression, respectively.

RESULTS

Enterococcus faecalis was detected in 33.3% and 88.9% of samples by culture and real-time PCR, respectively. Haemolytic strains were found in 36.4% of subjects. Non-haemolytic strains exhibited susceptibility to erythromycin and varying susceptibility to tetracycline, while all haemolytic strains were resistant to both antibiotics. Haemolytic strains significantly upregulated the expression of IL-8, OPG and RANKL in PDL cells (p < .05). Notably, the fold increases in these genes were higher: IL-8 (556.1 ± 82.9 vs. 249.6 ± 81.8), OPG (2.2 ± 0.5 vs. 1.3 ± 0.2) and RANKL (1.8 ± 0.3 vs. 1.2 ± 0.1). Furthermore, haemolytic strains had a greater effect on neutrophil migration (68.7 ± 15.2% vs. 46.9 ± 11.4%) and demonstrated a higher level of internalization into oral keratinocyte cells (68.6 ± 0.4% vs. 33.8 ± 0.5%) (p < .05). They also showed enhanced expression of virulence genes associated with haemolysin, surface proteins, collagen-binding and aggregation substances. Gelatinase activity was only detectable in non-haemolytic strains.

CONCLUSIONS

This study revealed that haemolytic strains E. faecalis possessed enhanced abilities in host invasion and a higher abundance of virulence factors, suggesting their potential contribution to more severe disease manifestations.

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.

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.

High-mobility group box 1 released by traumatic occlusion accelerates bone resorption in the root furcation area in mice

BACKGROUND AND OBJECTIVE

Traumatic occlusion can cause bone resorption without bacterial infection. Although bone resorption in periodontitis has been relatively well studied, little is known about bone resorption by traumatic occlusion. High-mobility group box 1 (HMGB1) is released from damaged tissue and has been recently shown to promote bone resorption in a murine periodontitis model and may also promote bone resorption by traumatic occlusion. The present study aimed to examine whether HMGB1 accelerates bone resorption by traumatic occlusion in mice.

MATERIALS AND METHODS

Occlusal trauma was induced in the lower left first molar of mice by bonding a wire to the upper left first molar, and bone resorption and osteoclast formation were evaluated histochemically. The expression of HMGB1, Toll-like receptor 4 (TLR4; the receptor for HMGB1), and receptor activator of NFκB ligand (RANKL; an essential osteoclast differentiation factor) was evaluated immunohistologically. In addition, mice were administrated with an anti-HMGB1-neutralizing antibody to analyze the role of HMGB1.

RESULTS

Bone resorption and osteoclast formation gradually increased until day 5 at the furcation area after the application of traumatic occlusion. Expression of HMGB1 was observed at the furcation area on day 1, but was attenuated by day 3. Expression of RANKL gradually increased until day 3, but was attenuated by day 5. Administration of anti-HMGB1 antibody significantly reduced the number of osteoclasts and the expression of RANKL and TLR4 at the furcation area.

CONCLUSION

Release of HMGB1 in the root furcation area accelerated bone resorption by up-regulating RANKL and TLR4 expression in mice with traumatic occlusion.

The Effect of High-Frequency Vibration on Tooth Movement and Alveolar Bone in Non-Growing Skeletal Class II High Angle Orthodontic Patients: Case Series

This study presents a novel technique utilizing high-frequency vibration to shorten treatment time and preserve alveolar bone in challenging orthodontic cases that have been treated with Invisalign^® clear aligners. Four non-growing orthodontic patients (age range 14–47 years old) with Class II skeletal patterns (convex profiles with retrognathic mandibles) who sought correction of their crowded teeth and non-surgical correction of their convex profiles were included in this study. These patients were treated using Invisalign clear aligners together with high-frequency vibration (HFV) devices (120 Hz) (VPro5™) that were used by all patients for five minutes per day during active orthodontic treatment. Vertical control and forward rotation of the mandible for each patient was achieved through pre-programming the Invisalign to produce posterior teeth intrusion. Successful forward rotation of the mandibles achieved in all patients led to improvement of their facial convex profiles (apical base relationship (ANB) improved 2.1 ± 0.5 degrees; FMA (Frankfurt mandibular plane angle) improved 1.2 + 1.1 degrees). Dental decompensation was achieved by lingual tipping of the lower incisors and palatal root torque of upper incisors. The use of HFV together with Invisalign facilitated achieving these results within a 12 ± 6 months period. In addition, more bone labial to the lower incisors after their lingual movement was noted. In conclusion, the use of HFV concurrent with SmartTrack Invisalign aligners allowed complex tooth movement and forward mandibular projection without surgery in non-growing patients with skeletal Class II relationships. The clinical impact and implications of this case series are: (1) the use of HFV facilitates complex orthodontic tooth movement including posterior teeth intrusion and incisor decompensation; (2) forward mandibular projection of the mandible and increased bone formation labial to lower incisors can be achieved in non-growing patients that may minimize the need for surgical intervention in similar cases or gum recession due to lower incisors labial inclination.

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.