Photobiomodulation in Periodontology and Implant Dentistry: Part 2

The efficacy of infrared diode laser in enhancing the regenerative potential of human periodontal ligament stem cells (hPDLSCs)

BACKGROUND

The present study aimed to investigate the effects of infrared diode laser irradiation on the proliferation and differentiation capacity of periodontal ligament stem cells (hPDLSCs), which are optimal cell sources for periodontal regeneration.

METHODS

hPDLSCs were isolated and characterized by flow cytometric analysis of mesenchymal stem cell markers, and their trilineage differentiation capacity was tested. hPDLSCs were then cultured and irradiated with infrared diode laser (970 nm) at a power of 200 mW and a fluence of 4 J/cm2 for 3 s. MTT assay was performed to assess cellular proliferation. Cell cycle analysis was performed, and the impact of infrared diode laser irradiation on the stemness and osteogenic differentiation potential of hPDLSCs was evaluated via RT‒PCR.

RESULTS

Infrared diode laser application enhanced the stemness, viability, proliferation, and differentiation of PDLSCs. Stem cell markers (OCT4, SOX2, and NANOG) were significantly upregulated in hPDLSCs exposed to laser irradiation. There was significant overexpression of RUNX2, ALP, OPN, and OCN on day 14 after laser application.

CONCLUSIONS

These findings provide valuable insights into the specific applications of infrared diode lasers to effectively regenerate periodontal tissues. The results can aid in the development of precise clinical protocols aimed at enhancing osseointegration and promoting tissue regeneration. Ultimately, the combination of infrared diode laser with hPDLSCs is promising for stimulating periodontal regeneration.

The effect of photobiomodulation therapy on implant stability: A systematic review and meta-analysis

This study was designed to determine the effect of photobiomodulation therapy on dental implant stability. A complete systematic search was performed in PUBMED/MEDLINE, COCHRANE library databases, EMBASE, SCOPUS, and Google Scholar databases on articles published until June 2024. All the RCTs and CCTs reported the solo impact of photobiomodulation on dental implant stability in humans were included. The means and standard deviation for implant stability and sample size were extracted for the meta-analysis. The statistical analysis was conducted using Stata 17 software, and random effect models were applied to assess the source of heterogeneity. The I2 statistic was used to estimate the significance of any discrepancies in the therapy result. After a full-text inspection, 17 articles were qualified for systematic review, and 14 were included in the meta-analysis. Statically significant differences in implant stability were observed between the laser and the control groups on weeks 2 in ISQ reporting groups (p = 0.01, CI 95%) and weeks 4 and 8 in PTV reporting groups (p < 0.001, CI 95%). Despite limitations, the study suggests that PBM therapy benefits patients with dental implants at different periods, particularly during the early phases of healing.

Improving Titanium Implant Stability with Photobiomodulation: A Review and Meta-Analysis of Irradiation Parameters

Objective: This analysis was designed to present a summary of available evidence that will inform practice and guide future research for photobiomodulation (PBM) after titanium implant placement procedures. Materials and methods: A systematic review was performed according to the Cochrane Collaboration and in line with Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) criteria. Two investigators screened the titles and abstracts, and reviewed articles for risk of bias. Online databases searched included PubMed, Embase, Scopus, and Web of Science. Terms were specific to the effects of PBM on dental implant stability. Results: Eight hundred fifty-six studies were identified, and 15 studies fulfilled the inclusion criteria. Light sources included both laser and light emitting diode (LED) devices. Wavelengths ranged from 618 to 1064 nm. The meta-analysis concluded that all 15 published studies were able to safely apply PBM near dental implants without adverse events. Laser and LED wavelengths that reported significant results included 618, 626, 830, 940 (2 × ), and 1064 nm. Conclusions: The use of adjunctive PBM can be safely prescribed after surgical placement of titanium implants. Six groups reported statistical significance for improving implant stability (four laser diode, two LED) in wavelengths ranging from 618 to 1064 nm. The amount of time spent delivering PBM was not a variable that differentiated whether a study reported significant results.

The Effect of Photobiomodulation Therapy on the Stability of Orthodontic Mini-implants in Human and Animal Studies: A Systematic Review and Meta-analysis

Introduction: The present study aimed to systematically explore available literature on the possible impact of photobiomodulation (PBM) therapy on the stability and success of orthodontic mini-implants. Methods: A comprehensive electronic search was conducted in PubMed, ISI Web of Science, Scopus, Cochrane and Embase databases for human and animal studies published until July 2021. Two independent researchers reviewed the studies based on specific eligibility criteria. Results: 15 studies were included in the systematic review after a comprehensive search. Ten studies were included in the meta-analysis. Four were human RCT studies that evaluated the stability with Preriotest. Three other human RCT studies and two animal studies had evaluated the Implant stability quotient (ISQ). Two human RCTs that had evaluated displacement of mini-implants were also analyzed. The analysis of Periotest stability results showed a positive effect of PBM on mini-implant stability at 30 and 60 days after implantation (P<0.05). In human studies using the ISQ method, a slight improvement was seen in the PBM groups; however, this was not statistically significant (CI=-1.92-2.70, SMD=0.39). In studies that examined the displacement of mini-implants, no statistically significant difference was observed between irradiated and non-irradiated groups (CI=-1.92-2.70, SMD=0.03). According to the results of animal studies, which had used the ISQ method, the use of laser was statistically effective in increasing the stability of mini-implants (SMD=1.43, CI=1.00-1.85). Conclusion: PBM therapy can be suggested as an adjunctive clinical method to improve the stability of mini-implant treatment. Further well-designed clinical studies can help establish evidence-based dosing and irradiation protocols.

Photobiomodulation in dental implant stability and post-surgical healing and inflammation. A randomised double-blind study

BACKGROUND

The aim of this randomized clinical trial was to evaluate the effect of diode laser photobiomodulation (PBM) on post-surgical healing, inflammation and implant stability.

METHODS

Forty dental implants were inserted into 13 patients. The implants were randomly divided into two groups. The test group (PBM+) underwent two sessions of PBM (combined diode laser of 630 and 808 nm), the first of which after surgery, and the second, 7 days after the surgical procedure. The control group (PBM-) received simulated laser treatment. The implant stability quotient (ISQ) was determined immediately after the surgical procedure, and 7 days, 4 and 8 weeks later. Post-surgical inflammation was assessed following the criteria described by Bloemen and Cols. Healing was calculated using the healing index (HI).

RESULTS

No differences were found in terms of the mean values of implant stability between the test and control groups over time. Only two of the implants (18.2%) from the PBM- group were classified with the maximum healing index (HI = 5), whereas in the PBM+ group, nine implants (45%) were classified with the aforementioned index (P < 0.0001). Using the logistic regression, it was determined that the non-application of the laser in the PBM- group caused an OR of 4.333 times of presenting inflammation (IC95% 1.150-16.323; P = 0.030).

CONCLUSIONS

The application of 808 nm infra-red laser for bone tissue, and 630 nm for mucosal tissue in two sessions is considered to be an effective way of reducing inflammation and improving early healing. More studies are needed to confirm these results.

Innovative Concepts and Recent Breakthrough for Engineered Graft and Constructs for Bone Regeneration: A Literature Systematic Review

BACKGROUND

For decades, regenerative medicine and dentistry have been improved with new therapies and innovative clinical protocols. The aim of the present investigation was to evaluate through a critical review the recent innovations in the field of bone regeneration with a focus on the healing potentials and clinical protocols of bone substitutes combined with engineered constructs, growth factors and photobiomodulation applications.

METHODS

A Boolean systematic search was conducted by PubMed/Medline, PubMed/Central, Web of Science and Google scholar databases according to the PRISMA guidelines.

RESULTS

After the initial screening, a total of 304 papers were considered eligible for the qualitative synthesis. The articles included were categorized according to the main topics: alloplastic bone substitutes, autologous teeth derived substitutes, xenografts, platelet-derived concentrates, laser therapy, microbiota and bone metabolism and mesenchymal cells construct.

CONCLUSIONS

The effectiveness of the present investigation showed that the use of biocompatible and bio-resorbable bone substitutes are related to the high-predictability of the bone regeneration protocols, while the oral microbiota and systemic health of the patient produce a clinical advantage for the long-term success of the regeneration procedures and implant-supported restorations. The use of growth factors is able to reduce the co-morbidity of the regenerative procedure ameliorating the post-operative healing phase. The LLLT is an adjuvant protocol to improve the soft and hard tissues response for bone regeneration treatment protocols.

Low-level laser irradiation enhances the proliferation and osteogenic differentiation of PDLSCs via BMP signaling

The aim of this in vitro study was to evaluate the effects of low-level laser therapy (LLLT) at different energy intensities on proliferation and osteogenesis of periodontal ligament stem cells (PDLSCs). We designed one control group, without irradiation and four testing groups, treated with LLLT (Nd:YAG;1064 nm) at 2, 4, 6, and 8 J/cm² for human PDLSCs. Cell proliferation was measured using colony-forming unit fibroblast assay and 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide assay. Osteogenic capacity of cells was determined by alkaline phosphatase (ALP) staining, ALP activity assay, Alizarin Red S staining, and the gene levels of runt-related transcription factor 2 (Runx2), ALP, osteocalcin, and bone morphogenetic protein 2 (BMP2). The effects of LLLT on secretion of TNF-α and IL-1β in PDLSCs were measured by enzyme-linked immunosorbent assay. BMP/Smad pathway was measured through the expression of Smad1/5/8 phosphorylation (P-Smad1/5/8). LDN-193189, an inhibitor of the BMP/Smad pathway, was used to explore the underlying effects of BMP/Smad signaling on the process of LLLT regulating the proliferation and osteogenesis of PDLSCs. Our results demonstrated LLLT could promote the proliferation and osteogenesis of PDLSCs at 2-6 J/cm² and LLLT at 8 J/cm² significantly suppress osteogenic differentiation of PDLSCs. Moreover, LLLT stimulated the secretion of TNFα and IL-β1. Finally, we found the irradiation positively modulates the P-Smad1/5/8 level. When the cells were treated with LDN-193189, the proliferation and osteogenic effects of LLLT on PDLSCs were attenuated. In conclusion, LLLT may upregulate the proliferation and bone formation ability of PDLSCs via the BMP/Smad signaling.

A Clinical Trial of Photobiomodulation Effect on Orthodontic Microscrews Stability Using a 635 nm Red Laser Light

Background: One of the procedures enhancing implants stability can be photobiomodulation. Objective: To assess the effect of a 635 nm wavelength on orthodontic microscrews stability, survival rate, and an individual patient's pain score. Materials and methods: The study was done with 15 subjects, 30 orthodontic microscrews with a length of 10 mm and diameter 1.4 mm. Implants inserted on the right and left side of the maxilla. The implants in the test group (G1) were irradiated with the laser at palatal and buccal part of peri-implant area (two points). The diode laser (SmartM PRO; Lasotronix, Warsaw, Poland) was used with the following settings: power: 100 mW, spot size: 0.5 cm², mean power density (irradiance): 200 mW/cm², in continuous wave (CW) mode, energy per point: 4 J, radiant exposure: 8 J/cm², time per point: 40 sec, the total energy dose (radiant energy) per session: 8 J in contact mode, handpiece diameter: 8 mm. Laser sessions: day of surgery and 3, 6, 9, 12, 15, 30 days later. Cumulative radiant energy was 59 J. Periotest appliance was used to assess the microscrews stability at day of surgery and 3, 6, 9, 12, 15, 30, 60 days later. Each patient received a survey for individual pain assessment (NRS-11) promptly after the implantation. Results: The analysis after 60 days revealed significantly higher secondary stability for the laser-irradiated microscrews group in comparison with control implants (G2 group) (p = 0.0037). We observed significantly higher stability in the experimental group compared with the control after 30 days (p = 0.0218). Moreover, we noted significantly higher microimplants stability for the control group in comparison with the test group, 9 days after implantation (p = 0.0374). Laser application had no effect on pain reduction noted in the first day in comparison with the control sites (p = 0.6690). No microscrews were lost in the study. Conclusions: Application of a 635 nm laser on peri-implant soft tissue increased the microscrews stability after 30 and 60 days.

Photo biostimulatory effect of low dose photodynamic therapy on human mesenchymal stem cells

BACKGROUND

Tissue engineering is one treatment to regenerate bone . Stem cell proliferation or differentiation can be stimulated by adjunctive approaches like photobiomodulation. Some studies suggested that, photodynamic therapy with low concentration of photosensitizers can stimulate cell differentiation as a photobiomodulation approach.

METHODS

Human bone marrow mesenchymal stem cell was isolated and then cultured in sterile medium. Two photosensitizer drugs as 5- aminolevulenic acid (1 mM) (5-ALA) and Methylene blue (1μM) (MB) were used in incubation culture media. In order to activate the photosensitizers, 630 and 660 nm wavelengths were irradiated with 1 J/cm2 energy density, respectively. Cell viability was assessed using MTT assay before and after laser irradiation, and also Alizarin red histologic test was used for calcium nodule formation.

RESULTS

performing the MTT test before irradiation showed that, the optimum concentrations were 1 mM for 5-ALA and 1μM for MB that were optimized. After laser irradiation, ALA group showed no osseous differentiation. In contrast, there was a significant calcium nodule formation in MB group compared with the control one.

CONCLUSIONS

Photodynamic therapy with low photosensitizer concentration and low doses of laser energy density may improve osteogenic differentiation. Accordingly, MB had stimulatory effect on bone marrow derived mesenchymal stem cells. However, 5-ALA did not show this effect.

Effect of 808 nm Semiconductor Laser on the Stability of Orthodontic Micro-Implants: A Split-Mouth Study

BACKGROUND

To evaluate the effect of photobiomodulation (PBM) on orthodontic micro-implants (n = 44; 14 women, 8 men).

METHODS

PBM with 808 nm diode laser was applied immediately, 3, 6, 9, 12, 15, and 30 days post the implantation. Results were assessed within same time frames and additionally after 60 days to check for implants stability using the Periotest device. Patients pain experiences following the first day post-treatment and potential loss of micro-implants after 60 days were recorded. The procedure involved insertion of mini-implants in the maxilla for the laser group (L, n = 22) and negative control group (C, n = 22). Irradiation was carried buccally and palatally with respect to the maxillary ridge (2 points). The energy per point was 4 J (8 J/cm2), total dose was 56 J.

RESULTS

Patients did not report significant differences in terms of pain experiences comparing the L and C groups (p = 0.499). At 30 days post-treatment, higher secondary stability of implants was observed in the laser group (Periotest Test Value, PTV 6.32 ± 3.62), in contrast to the controls (PTV 11.34 ± 5.76) (p = 0.004). At 60 days post-treatment, significantly higher stability was recorded in the laser group (PTV 6.55 ± 4.66) compared with the controls, PTV (10.95 ± 4.77) (p = 0.009). Conclusions: Application of the 808 nm diode laser increased secondary micro-implant stability.