Effects of increased low-level diode laser irradiation time on extraction socket healing in rats

A radiographic and histological study to compare red (650 nm) versus near infrared (810 nm) diode lasers photobiomodulation for alveolar socket preservation

Previous findings indicated that the laser photobiomodulation is more effective than the control or placebo in preserving the alveolar socket. This study aimed to compare two different lasers regarding their effectiveness in aiding alveolar socket preservation. Twenty extraction sockets were selected then divided into two equal groups. Group A was exposed to 650 nm Diode laser, and Group B to 810 nm Diode laser following the same protocol and parameters after a standard alveolar socket preservation procedure with collagen plug. Radiographic analysis with cone beam computed tomography was done to compare the alveolar bone surface area immediately after extraction and three months post-operatively, while bone samples collected before implant drilling were histologically examined for newly formed bone evaluation and histomorphometric analysis in terms of percentage of new bone surface area, percentage of unmineralized bone and finally, immunohistochemical analysis of Osteocalcin reaction surface area as well as optical density. Radiographically, infrared (810 nm) Diode effect on alveolar bone surface area has significantly exceeded the red laser, while histologically, red (650 nm) Diode has demonstrated statistical significance regarding all parameters; newly formed bone surface area percentage, unmineralized bone area percentage and finally Osteocalcin bone marker reaction surface area percentage and optical density. Under the specified conditions and laser parameters, photobiomodulation using the 810 nm Diode got the upper hand radiographically, yet histologically, the red 650 nm Diode managed to dominate all histological parameters when both employed as an adjunct to alveolar socket preservation procedures.

Effect of 980 nm photobiomodulation delivered by a handpiece with Gaussian vs. Flat-Top profiles on proliferation and differentiation of buccal fat pad stem cells

The aim of this study was to compare the effectiveness of the Gaussian and Flat-Top profiles in proliferation and differentiation of mesenchymal stem cell of buccal fat pad. Based on the timing schedule and type of laser handpieces, the cells were assigned to a control group with no radiation, and two irradiation test groups (980 nm) with Flat-Top (F) (power of 1.1 W, beam area of 1 cm2 ) and standard Gaussian (G) (power of 0.7 W, beam area of 0.5 cm2 ) handpieces. Each test group was divided into three subgroups, receiving one time (60 J/cm2 ), two times (120 J/cm2 ), and three times (180 J/cm2 ) irradiation. 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) and Annexin V tests were performed. The Alizarin Red staining and polymerase chain reaction tests were done both at the beginning and the end of the first and second weeks. The degree of mineralization and expression of osteogenic markers, RUNX2, OCN, and OPN were evaluated. Based on the MTT and Annexin V test results, both test groups outperformed the control group in degrees of cell proliferation during the first day of laser irradiation (p < 0.05). After one and two times irradiation, the expression of osteogenic markers in the test groups was significantly higher than the control group. PBM with Flat-Top and Gaussian handpieces can enhance ossification and cell differentiation regardless of the type of handpieces.

Effects of NGF and Photobiomodulation Therapy on Crush Nerve Injury and Fracture Healing: A Stereological and Histopathological Study in an Animal Model

Study Design

A stereological and histopathological study in an animal model.

Objective

This study explores the effects of the nerve growth factor and photobiomodulation therapy on the damaged nerve tissue and fracture healing.

Methods

A total of 24 rabbits were divided into 4 groups: control group (n = 5), nerve growth factor (NGF) group (n = 7), photobiomodulation (PBMT) group (n = 6), and nerve growth factor and photobiomodulation therapy (NGF+PBMT) group (n = 6). The vertical fracture was performed between the mental foramen and the first premolar, and the mental nerve was crushed for 30 seconds with a standard serrated clamp with a force of approximately 50 N in all groups. The control group received an isotonic solution (.02 mL, .09% NaCl) to the operation site locally. The NGF group received 1 μg human NGF-β/.9% .2 mL NaCl solution for 7 days locally. The PBMT group received PBMT treatment (GaAlAs laser, 810 nm, .3 W, 18 J/cm2) every 48 hours for 14 sessions following the surgery. The NGF+PBMT group received both NGF and PBMT treatment as described above. After 28 days, the bone tissues and mental nerves from all groups were harvested and histologically and stereologically analyzed.

Results

According to the stereological results, the volume of the new vessel and the volume of the new bone were significantly higher in the PBMT group than in other groups (P < .001). According to the histopathological examinations, higher myelinated axons were observed in experimental groups than in the control group.

Conclusions

As a result, PBMT has beneficial effects on bone regeneration. Based on the light microscopic evaluation, more regenerated axon populations were observed in the NGF group than in the PBMT and PBMT + NGF groups in terms of myelinated axon content.

The effect of bone remodeling with photobiomodulation in dentistry: a review study

Photobiomodulation (PBM) has been emerging as a promising alternative therapy in dentistry. However, various parameters of PBM are used in different studies, and there is limited cumulative data on PBM for improving bone formation in clinical trials. The aim of this review was to evaluate the effectiveness of PBM in the process of bone remodeling in dentistry using randomized controlled trials. Initially, a total of 1,011 articles published from January 2008 to December 2021 were retrieved from five electronic databases (PubMed, Scopus, Cochrane Library, EMBASE, and CINAHL). After a two-step review, nine articles met the inclusion criteria. The parameter of PBM, group, treatment sessions, assessment times and outcomes of the included studies were reviewed. Eighty-nine percent of the studies revealed positive effects on bone formation between the laser group and the control group. Only one article reported that light-emitting diode did not significantly enhance osteogenesis. Additionally, the present study shows that Gallium aluminum arsenide of near infrared (NIR) laser with continuous mode is the most commonly used form of PBM. The biostimulatory effects are dependent on several parameters, with wavelength and dose being more important than others. Based on this review, it is suggested that the NIR range and an appropriate dose of PBM could be used to increase the efficiency of stimulating bone healing and remodeling. However, standardization of treatment protocols is needed to clarify therapeutic strategies in dentistry.

Effects of Photobiomodulation Therapy on Hard Tissue Healing in Rat Tooth Extraction Sockets

Objective: To investigate the effects of photobiomodulation therapy (PBMT) on hard tissue healing in rat maxillary first molar extraction sockets. Methods: A total of 20 male Wistar rats were used in the study. The right extraction sockets were irradiated with a Ga-Al-As laser (500 mW, 980 nm) for 51.7 J/cm2 every 24 h for 7 days, while the left sockets served as controls. Rats were sacrificed on days 3, 7, 14, and 28 after tooth extraction, and microcomputed tomography (CT) analysis, histopathological evaluation, and enzyme-linked immunosorbent assay (ELISA) were conducted at different time points. Results: Micro-CT analysis showed that the percentage of bone volume/tissue volume (TV) and bone mineral density were significantly higher in the experimental group compared to the control group on day 28 (p < 0.05). Histopathological evaluation revealed that PBMT promoted new bone formation and accelerated bone remodeling. ELISA demonstrated a significant increase in alkaline phosphatase expression in the laser sides on days 7 and 14 (p < 0.05). Conclusions: One application postextraction followed by seven consecutive daily applications of PBMT can effectively promote hard tissue healing in rat maxillary first molar extraction sockets.

Nd:YAG-photobiomodulation enhanced ADSCs multilineage differentiation and immunomodulation potentials

To investigate the effects of Nd: YAG (1064 nm) photobiomodulation on multilineage differentiation and immunomodulation potentials of adipose tissue-derived stem cells (ADSCs) in vitro and in vivo. For in vitro experiments, cells were divided into the control group (non-irradiated control ADSCs) and photobiomodulation groups. 0.5 J/cm2, 1 J/cm2, 2 J/cm2, and 4 J/cm2 were used for proliferation assays; for ADSCs adipogenic differentiation assays, 0.5 J/cm2, 1 J/cm2 were applied; 1 J/cm2 was used for migration and immunomodulation assays. The differentiation abilities were assessed by qPCR, Oil Red O staining, and Alizarin Red staining. The immunomodulation potential was assessed by qPCR and human cytokine array. DSS-induced colitis model. was used to test the effect of photobiomodulation on ADSCs immunomodulation potentials in vivo. Nd:YAG-based photobiomodulation dose-dependently promoted ADSCs proliferation and migration; 1 J/cm2 showed the best promotion effect on proliferation. Moreover, Nd:YAG photobiomodulation promoted ADSCs osteogenic differentiation and brown adipose adipogenic differentiation. The potential immunomodulation assays showed Nd:YAG photobiomodulation improved Anti-inflammation capacity of ADSCs and photobiomodulation irradiated ADSCs effectively alleviated DSS-induced colitis severity in vivo. Our study suggests Nd:YAG photobiomodulation might enhance the ADSCs multilineage differentiation and immunomodulation potentials. These results might help to enhance ADSCs therapeutic effects for clinical application. However, further studies are needed to explore the mechanisms of Nd:YAG photobiomodulation promoting multilineage differentiation and immunomodulation potentials of ADSCs.

Angiogenetic and anti-inflammatory effects of photobiomodulation on bone regeneration in rat: A histopathological, immunohistochemical, and molecular analysis

Post-surgical bone defects require new alternative approaches for a better healing process. For this matter, photobiomodulation therapy (PBMT) has been used in order to improve the process of healing, pain, and inflammation reduction and tissue rejuvenation. This study is set to evaluate the effect of PBMT on angiogenic and inflammatory factors for bone regeneration in rat post-surgical cranial defects. Thirty male Wistar rats were distributed accidentally into two groups (Subdivided into 3 groups according to their follow-up durations). During operation, an 8-mm critical-sized calvarial defect was made in each rat. A continuous diode laser was used (power density 100 mW/cm², wavelength 810 nm, the energy density of 4 J/cm²). Bone samples were assessed histomorphometrically and histologically after hematoxylin and eosin (H&E) staining. ALP, PTGIR, OCN, and IL-1 levels were measured by RT-PCR. VEGF expression was studied by immunohistochemistry analysis. The level of IL-1 expression decreased significantly in the PBMT group compared to the control after 7 days (p < 0.05), while, the PTGIR level was improved significantly compared to the control group after 7 days. Furthermore, levels of OCN and ALP improved after PBM use; however, the alterations were not statistically meaningful (p > 0.05). Evaluation with IHC displayed a significant rise in VEGF expression after 3 days in the PBMT group compared to the control (p > 0.05). In this study's conditions, the results showed a meaningful alteration in osteogenic, inflammatory, and angiogenic mediators in post-surgical calvarial defect following PBMT. It appears that PBM can accelerate angiogenesis in the bone healing procedure which can be helpful in bone tissue engineering.

Photobiomodulation effect in tumoral necrosis factor-alpha(TNF-α) on the viability of random skin flap in rats

The aim of this study was to investigate the effect of red laser (660 nm) photobiomodulation (PBM) with different energies on tumor necrosis factor-alpha(TNF-α) expression for random skin flap viability in rats. Twenty-four Wistar rats were divided into three groups: sham group (SG), PBM laser group with an energy dose of 0.29 J (0.29G), and PBM laser group with an energy dose of 7.30 J (7.30G). A cranially based dorsal skin flap measuring 10 × 4 cm was raised and a plastic barrier was placed between the flap and its bed. PBM was applied in 3 timepoints: in the immediate postoperative period, in the 1^st and in the 2^nd postoperative days; the animals were euthanized on the 7^th postoperative day. The assessments included: TNF-α expression of 3 different flap areas (proximal, medial and distal), by immunohistochemistry; percentage of skin flap necrosis area, by the paper template method. The statistical analysis was performed through the Kruskal-Wallis and Mann-Whitney tests, the level of significance adopted was 5% (p < 0.05). TNF-α expression was significantly lower for 7.30G in the proximal area, reduced for SG in the medial point, and larger for 7.30G in the distal area. The percentage of flap necrosis area was significantly reduced for 7.30G. Higher energy doses are more efficacious than lower energy doses for modulating TNF-α expression. PBM with an energy dose of 7.30 J was effective in reducing the expression of TNF-α and increase skin flap viability.

Effects of Physical Stimulation in the Field of Oral Health

Physical stimulation has been widely used in clinical medicine and healthcare due to its noninvasiveness. The main applications of physical stimulation in the oral cavity include laser, ultrasound, magnetic field, and vibration, which have photothermal, cavitation, magnetocaloric, and mechanical effects, respectively. In addition, the above four stimulations with their unique biological effects, which can play a role at the gene, protein, and cell levels, can provide new methods for the treatment and prevention of common oral diseases. These four physical stimulations have been used as important auxiliary treatment methods in the field of orthodontics, implants, periodontal, dental pulp, maxillofacial surgery, and oral mucosa. This paper systematically describes the application of physical stimulation as a therapeutic method in the field of stomatology to provide guidance for clinicians. In addition, some applications of physical stimulation in specific directions are still at the research stage, and the specific mechanism has not been fully elucidated. To encourage further research on the oral applications of physical stimulation, we elaborate the research results and development history of various physical stimuli in the field of oral health.

Near-infrared 940-nm diode laser photobiomodulation of inflamed periodontal ligament stem cells

Photobiomodulation (PBM) is an acceptable method of stimulating stem cells through its non-invasive absorption by the cell photoreceptors and the induction of cellular response. The current research was aimed at evaluating the effect of near-infrared PBM on proliferation and osteogenic differentiation in inflamed periodontal ligament stem cells (I-PDLSCs). I-PDLSCs were isolated and characterized. Third passage cells were irradiated with 940-nm laser at an output power of 100 mW in a continuous wave. A fluence of 4 J/cm² in three sessions at 48-h intervals was applied and compared with non-irradiated controls. Cell viability and proliferation were evaluated by MTT assay. Alkaline phosphatase activity, quantitative Alizarin red staining test, and q-RT-PCR were used to evaluate the osteogenic properties of the I-PDLSCs in four groups of (a) osteogenic differentiation medium + laser (ODM + L), (b) osteogenic differentiation medium without laser (ODM), (c) non-osteogenic differentiation medium + laser (L), and (d) non-osteogenic differentiation medium (control). There was a non-significant increase in the viability of cells at 48- and 72-h post last laser irradiation. Alizarin red staining revealed no significant stimulatory effect of PBM at 14 and 21 days. However, alkaline phosphatase activity was significantly higher in the L + ODM group. Expression of osteogenic-related genes had a statistically significant increase at 21-day post irradiation. The irradiation used in the present study showed no significant increase in the proliferation of I-PDLSCs by PBM. However, expression levels of osteogenic-related genes and alkaline phosphatase activity were significantly increased in irradiated groups.

Efficacy of Flat-Top Hand-Piece Using 980 nm Diode Laser Photobiomodulation on Socket Healing after Extraction: Split-Mouth Experimental Model in Dogs

The objective was to evaluate the effect of photobiomodulation (PBM) using 980 nm diode laser therapy (0.60 W, 0.77 W cm^-2 , 36 J, 46 J cm^-2 , 60 s) irradiated in continuous wave mode by flat-top hand-piece on socket healing in the maxilla and mandible. A split-mouth experimental design was performed on 6 dogs. The 3^rd premolar tooth was extracted from the maxilla and mandibles for both sides. The right-sided sockets were irradiated (PBM group), and the left-sided sockets were kept as control. Irradiation was done after extraction and at 48-h interval for 14 days. Both the buccal and lingual sides were irradiated to reach a total irradiation time of 120 s. Bone density was evaluated at 3, 4 and 5 weeks using cone beam computed tomography. We showed that maxillary sockets in the PBM group had higher bone density compared to control one at 3, 4, 5 weeks (P = 0.029, <0.001, <0.001), respectively. Mandibular sockets revealed no significant difference between PBM and control at 3 weeks (P = 0.347), while at 4 and 5 weeks PBM group showed higher bone density (P = 0.004, <0.001). In both groups, there was a significant increase (P < 0.001) in bone density by time which was higher in the PBM group. We concluded that PBM using a flat-top hand-piece of 980-nm improved the bone density of extraction sockets.

Interaction between Laser Light and Osteoblasts: Photobiomodulation as a Trend in the Management of Socket Bone Preservation-A Review

Simple Summary

Dental implants are becoming an accepted tool, and thousands of implants are placed every year by specialists and general practitioners. However, more than 10% of bone surgeries and related procedures can show healing complications as a consequence of infections, tissue damage, or inadequate blood supply. In particular, a deficient blood supply impacts on the optimal healing process because of altered oxygen delivery to cells in the wound and a decrease in their energy supply. Researchers showed how red and infrared light affects key cellular pathways by interacting with specific photoacceptors located within the cell, particularly in mitochondria. Low-level laser therapy or photobiomodulation (PBM), as the recent medical subject heading defines it, is based on a light–cell interaction, which modifies cell metabolism by increasing oxygen consumption and ATP production through mitochondria. Although not all aspects of this interconnection are completely described, many in vitro and in vivo studies showed the benefit of PBM in wound defect management. For instance, treatment of bone with PBM results in a greater amount of new-formed osteoblasts and matrix, an increase in collagen synthesis, and microvascular reestablishment. In our review, we highlight the osteoblast–light interaction, and the in vivo therapeutic tool of PBM for socket preservation is discussed.

Abstract

Bone defects are the main reason for aesthetic and functional disability, which negatively affect patient’s quality of life. Particularly, after tooth extraction, the bone of the alveolar process resorbs, limiting the optimal prosthetic implant placement. One of the major pathophysiological events in slowly- or non-healing tissues is a blood supply deficiency, followed by a significant decrease in cellular energy amount. The literature shows that photons at the red and infrared wavelengths can interact with specific photoacceptors located within the cell. Through this mechanism, photobiomodulation (PBM) can modify cellular metabolism, by increasing mitochondrial ATP production. Here, we present a review of the literature on the effect of PBM on bone healing, for the management of socket preservation. A search strategy was developed in line with the PRISMA statement. The PubMed and Scholar electronic databases were consulted to search for in vivo studies, with restrictions on the year (<50 years-old), language (English), bone socket preservation, and PBM. Following the search strategy, we identified 269 records, which became 14, after duplicates were removed and titles, abstract and inclusion-, exclusion-criteria were screened. Additional articles identified were 3. Therefore, 17 articles were included in the synthesis. We highlight the osteoblast–light interaction, and the in vivo therapeutic tool of PBM is discussed.

Effectiveness of Low-Level Laser Irradiation in Reducing Pain and Accelerating Socket Healing After Undisturbed Tooth Extraction

Introduction: This study aimed to determine the effect of low-level laser therapy (LLLT) on reducing complications following tooth extraction. Methods: This randomized clinical trial consisted of 40 subjects who underwent lower molar extraction. The patients were randomly assigned to 4 groups. Group 1 was irradiated with a 660 nm laser (200 mW, 30 seconds radiation to lingual, buccal and occlusal surfaces of the socket, 6 J/area). In group 2, an 810 nm laser was applied similar to group 1. In group 3, a combination of 660 and 810 nm lasers was used. The patients in group 4 served as a placebo group. LLLT was performed after 0.5-1 hour of extraction and 2 days later. The participants were asked to record pain degree using a visual analogue scale (VAS) over 7 days. The amount of wound healing was evaluated on the third and seventh days. Results: There was no significant difference in pain scores among the groups at any of the assessment intervals (P >0.05). The between-group differences in wound healing scores were small and insignificant (P >0.05). Conclusion: LLLT with 660 nm or 810 nm lasers or their combination had no greater effect than the placebo laser for reducing the complications of tooth extraction.

The Effect of Cigarette Smoking And Low-Level Laser Irradiation in RANK/RANKL/OPG Expression

The objective of this study was to investigate the effects of low-level laser therapy (LLLT) and cigarette smoke on alveolar socket osteoclastogenesis signaling after tooth extraction, in rats. Sixty male Wistar rats were randomly assigned to four groups with 15 animals each: Control Group (with right maxillary molar extraction - ME), Experimental I (with ME and LLLT), Experimental II (with ME and cigarette smoke) and Experimental III group (with ME, LLLT and cigarette smoke). Euthanasia was performed at 3, 7 and 14 days postoperative. qRT-PCR was used to evaluate expression of Tnfrsf11a (RANK), Tnfsf11 (Rankl) and Tnfrsf11b (OPG). Data were submitted to statistical analysis using two-way ANOVA followed by Bonferroni test (α=0.05). There was an upregulation of RANK, RANKL and OPG genes over all the time of healing in Exp I group compared to control group. Exp II group showed a decreased expression of all genes over time, whereas Exp III genes expression were higher than Exp II values but lower than Control and Exp I values over time. The results of this study concluded that the LLLT had a positive effect, whereas cigarette smoke had a negative effect on RANK, RANKL and OPG gene expression in bone remodeling process.

Photobiomodulation as an adjunctive therapy for alveolar socket preservation: a preliminary study in humans

Bone remodeling results in loss of alveolar bone height and thickness. Photobiomodulation (PBM) based on photochemical stimulation by low-intensity lasers emerges as an adjunctive therapy for alveolar socket preservation. Our study aimed to evaluate the effects of PBM therapy on alveolar bone repair. Twenty healthy patients in need of bilateral extraction of lower molars were enrolled in this split-mouth randomized and blind clinical trial. The extraction sites were randomly selected to receive either the PBM therapy with a CW GaAIAs diode laser (808 nm; 0.028 mm²; 0.1 W; 3.6 W/cm²; 89 J/cm²; 2.5 J/point) or no treatment (Control). Bone biopsies were harvested 45 days after the dental extraction and evaluated using micro-computerized tomography (μCT), morphometric, and histological analysis. Data were compared using the paired t test, and the level of significance was set at 5%. Bone surface (p = 0.029), bone surface/total volume (p = 0.028), trabecular number (p = 0.025), and connectivity density (p = 0.029) were higher at the PBM group compared with Control. The histological observations confirmed the μCT findings. PBM samples exhibited higher number of organized and connected bone trabeculae along with higher density of blood vessels than Control. Control samples displayed a dense and highly cellular connective tissue at the central area accompanied by the presence of immature bone trabeculae at the periphery. Our results indicated that the PBM therapy improved the newly bone trabeculae formation and their connectivity which increased bone surface, indicating the positive effect of the laser on alveolar human socket repair.

The Effectiveness of the Low-Level Laser, Antibiotic and Surgical Therapy in the Treatment of Medication-Related Osteonecrosis of the Jaws: A Case Report

Introduction: Bisphosphonates consist of a range of drugs used in the treatment of osteopathy or some osteotropic malignancies. Medication-related osteonecrosis of the jaw (MRONJ) is a serious adverse consequence of their use. Conventional treatment is not always effective, so it is necessary to resort to the use of adjuvant therapies. This study aimed to evaluate the effectiveness of the association of surgery, antibiotic therapy and low-level laser (LLL) therapy as a treatment strategy for MRONJ through the presentation of a clinical case. Case Presentation: A 49-year-old female patient presented for the diagnosis and treatment of bone lesions in the maxillae. The patient reported that she had used zoledronate for 1 year. Five years later there were 2 painless bone lesions on both sides of the maxilla, following the extraction of the first upper molars. Clinical, tomographic and histopathologic examination established the diagnosis of MRONJ. The treatment consisted of the curettage of the necrotic bone, antibiotic and thirteen LLL therapy sessions. Integral mucosal healing was observed after a two-month follow-up and no symptoms were detected. The patient was evaluated at 6 and 12 postoperative months without complications. Conclusion: The combination of surgery, antibiotic therapy, and LLL therapy has shown to be effective in the treatment of MRONJ.

Photobiomodulation therapy (PBMT) in bone repair: A systematic review

BACKGROUND

Photobiomodulation therapy (PBMT) using low-level laser influences the release of several growth factors involved in the formation of epithelial cells, fibroblasts, collagen and vascular proliferation, besides accelerating the synthesis of bone matrix due to the increased vascularization and lower inflammatory response, with significant increase of osteocytes in the irradiated bone. Considering its properties, beneficial effects and clinical relevance, the aim of this review was to analyze the scientific literature regarding the use of PBMT in the process of bone defect repair.

METHODS

Electronic search was carried out in PubMed/MEDLINE^Ⓡ and Web of Science databases with combination of the descriptors low-level laser therapy AND bone repair, considering the period of publication until the year 2018.

RESULTS

The literature search identified 254 references in PubMed/MEDLINE and 204 in Web of Science, of which 33 and 4 were selected, respectively, in accordance with the eligibility requirements. The analysis of researches showed articles using PBMT in several places of experimentation in the subjects, different types of associated biomaterials, stimulatory effects on cell proliferation, besides variations in the parameters of use of laser therapy, mainly in relation to the wavelength and density of energy. Only four articles reported that the laser did not improve the osteogenic properties of a biomaterial.

CONCLUSIONS

Many studies have shown that PBMT has positive photobiostimulatory effects on bone regeneration, accelerating its process regardless of parameters and the use of biomaterials. However, standardization of its use is still imperfect and should be better studied to allow correct application concerning the utilization protocols.

Effect of Combined Application of Growth Factors and Diode Laser Bio-Stimulation on the Osseo Integration of Dental Implants

BACKGROUND:

The success of implants is associated first with their osseointegration, and later on with their survival rate. In recent years, many efforts have been exerted to develop implant design, geometry, materials and techniques to enhance the osseointegration process and also to increase the success rate of implant procedures. New techniques, like leukocyte and platelet-rich fibrin (L-PRF) and low-level laser treatment (LLLT), have been developed to enhance the osseointegration around dental implants.

AIM:

This study aims at accelerating bone osseointegration process around dental implant using new techniques to increase the success rate, to allow immediate or early loading of a dental implant, and to make a comparison between the various new techniques in dental implant procedures to figure out which technique will achieve the best results.

METHODS:

The study was conducted on a random sample of 40 male patients. Dental implants were placed in the posterior areas of the lower jaw. Patients were divided randomly into 4 groups; control group, LLLT group, L-PRF group and L-PRF plus LLLT group. They were assessed using cone-beam computed tomography (CBCT).

RESULTS:

The results showed significant differences between all groups over different measured times. All the groups showed improvement in comparison with Normal group, where L-PRF group showed the best result followed by (L-PRF+LLLT) group, while the LLLT group showed the least improvement in comparison with bothL-PRF group and (L-PRF+LLLT) group.

CONCLUSION:

The study demonstrates that L-PRF gives a better performance in the osseointegration around dental implants than LLLT.

The influence of LLLT applied on applied on calvarial defect in rats under effect of cigarette smoke

Objective

Considering the global public health problem of smoking, which can negatively influence bone tissue repair, the aim of this study is to analyze the influence of photobiomodulation therapy (PBM) on calvaria defects created surgically in specimens under the effect of cigarette smoke and analyzed with use of histomorphometric and immunohistochemistry techniques.

Methodology

Calvaria defects 4.1 mm in diameter were surgically created in the calvaria of 90-day-old rats (n=60) that were randomly divided into 4 experimental groups containing 15 animals each: control group (C), smoking group (S), laser group (L), and smoke associated with laser group (S+L). The animals were subjected to surgery for calvaria defects and underwent PBM, being evaluated at 21, 45, and 60 days post-surgery. The specimens were then processed for histomorphometric and immunohistochemistry analyses. The area of bone neoformation (ABN), percentage of bone neoformation (PBNF), and the remaining distance between the edges of the defects (D) were analyzed histometrically. Quantitative analysis of the TRAP immunolabeled cells was also performed. The data were subjected to analysis of variance (ANOVA) in conjunction with Tukey’s test to verify the statistical differences between groups (p<0.05).

Results

The smoking group showed less ABN compared to the other experimental groups in all periods, and it also showed more D at 21 days compared to the remaining groups and at 45 days compared to the laser group. The smoking group showed a lower PNBF compared to the laser group in all experimental periods and compared to smoking combined with LLLT group at 21 days.

Conclusions

PBM acted on bone biomodulation, thus stimulating new bone formation and compensating for the negative factor of smoking, which can be used as a supportive therapy during bone repair processes.

Molecular impacts of photobiomodulation on bone regeneration: A systematic review

Photobiomodulation (PBM) encompasses a light application aimed to increase healing process, tissue regeneration, and reducing inflammation and pain. PBM is specifically aimed to modify the expression of cellular molecules; however, PBM impacts on cellular and molecular pathways especially in bone regenerative medicine have been investigated in scattered different studies. The purpose of the current study is to systematically review evidence on molecular impact of PBM on bone regeneration. A comprehensive electronic search in Medline, Scopus, EMBASE, EBSCO, Cochrane library, web of science, and google scholar was conducted from January 1975 to October 2018 limited to English language publications on administrations of photobiomodulation for bone regeneration which evaluated biological factors. In addition, hand search of selected journals was done to retrieve all articles. This systematic review was performed based on PRISMA guideline. Among these studies, five articles reported in vitro results, twelve articles were in vivo, and three of them were clinical trials. The data tabulated according to the type of markers (osteogenic markers, angiogenic markers, growth factors, and inflammation mediators). PBM's effects depend on many parameters which energy density is more important than the others. PBM can significantly enhance expression of osteocalcin, collagen, RUNX-2, vascular endothelial growth factor, bone morphogenic proteins, and COX-2. Although since the heterogeneity of the studies and their limitations, an evidence-based decision for definite therapeutic application of PBM is still unattainable, the findings of our review can help other researchers to ameliorate their study design and elect more efficient approach for their investigation.

The efficacy of low-level 940 nm laser therapy with different energy intensities on bone healing

The aim of this study was to evaluate the efficacy of low-level 940 nm laser therapy with energy intensities of 5, 10 and 20 J/cm2 on bone healing in an animal model. A total of 48 female adult Wistar rats underwent surgery to create bone defects in the right tibias. Low-level laser therapy (LLLT) was applied immediately after surgery and on post-operative days 2, 4, 6, 8, 10 and 12 in three study groups with energy intensities of 5 J/cm2, 10 J/cm2 and 20 J/cm2 using a 940 nm Gallium-Aluminium-Arsenide (Ga-Al-As) laser, while one control group underwent only the tibia defect surgery. All animals were sacrificed 4 or 8 weeks post-surgery. Fibroblasts, osteoblasts, osteocytes, osteoclasts and newly formed vessels were evaluated by a histological examination. No significant change was observed in the number of osteocytes, osteoblasts, osteoclasts and newly formed vessels at either time period across all laser groups. Although LLLT with the 10 J/cm2 energy density increased fibroblast activity at the 4th week in comparison with the 5 and 20 J/cm2 groups, no significant change was observed between the laser groups and the control group. These results indicate that low-level 940 nm laser with different energy intensities may not have marked effects on the bone healing process in both phases of bone formation.

Peri-implant osseointegration after low-level laser therapy: micro-computed tomography and resonance frequency analysis in an animal model

The purpose of the present study is to evaluate the effects of low-level laser therapy on the osseointegration process by comparing resonance frequency analysis measurements performed at implant placement and after 30 days and micro-computed tomography images in irradiated vs nonirradiated rabbits. Fourteen male New Zealand rabbits were randomly divided into two groups of seven animals each, one control group (nonirradiated animals) and one experimental group that received low-level laser therapy (Thera Lase®, aluminum-gallium-arsenide laser diode, 10 J per spot, two spots per session, seven sessions, 830 nm, 50 mW, CW, Ø 0.0028 cm²). The mandibular left incisor was surgically extracted in all animals, and one osseointegrated implant was placed immediately afterward (3.25ø × 11.5 mm; NanoTite, BIOMET 3i). Resonance frequency analysis was performed with the Osstell® device at implant placement and at 30 days (immediately before euthanasia). Micro-computed tomography analyses were then conducted using a high-resolution scanner (SkyScan 1172 X-ray Micro-CT) to evaluate the amount of newly formed bone around the implants. Irradiated animals showed significantly higher implant stability quotients at 30 days (64.286 ± 1.596; 95 % confidence interval (CI) 60.808-67.764) than controls (56.357 ± 1.596; 95 %CI 52.879-59.835) (P = .000). The percentage of newly formed bone around the implants was also significantly higher in irradiated animals (75.523 ± 8.510; 95 %CI 61.893-89.155) than in controls (55.012 ± 19.840; 95 %CI 41.380-68.643) (P = .027). Laser therapy, based on the irradiation protocol used in this study, was able to provide greater implant stability and increase the volume of peri-implant newly formed bone, indicating that laser irradiation effected an improvement in the osseointegration process.

High-frequency pulsed low-level diode laser therapy accelerates wound healing of tooth extraction socket: An in vivo study

BACKGROUND AND OBJECTIVE

This study aimed to evaluate the effects of high-frequency pulsed (HiFP) low-level laser therapy (LLLT) on early wound healing of tooth extraction sockets in rats.

STUDY DESIGN/MATERIALS AND METHODS

Bilateral maxillary first molars were extracted from 6-week-old Sprague-Dawley rats. Sockets on the right were treated by HiFP low-level diode laser irradiation (904-910 nm); the left sides served as unirradiated controls. LLLT (0.28 W, 30 kHz, 200-ns pulse, 0.6% duty cycle, 61.2 J/cm² total power density) was employed immediately after extraction and every 24 hours thereafter. The maxillae including the sockets were resected 3 or 7 days after extraction. Soft-tissue healing was evaluated on days 0, 3, and 7. The bone mineral content (BMC), bone volume (BV), and bone mineral density (BMD) of the extraction sockets were evaluated by microcomputed tomography, and histomorphometric analysis was carried out on day 7. Real-time PCR analysis of osteogenic marker expression and immunohistochemical detection of proliferating cell nuclear antigen (PCNA)-positive cells were performed on day 3.

RESULTS

Compared with control sites, the un-epithelialized areas of the extracted sites were significantly reduced by irradiation (P = 0.04), and the BMC, BV, and BMD of laser-treated sites were significantly increased (P = 0.004, 0.006, and 0.009, respectively). On day 7, the mean height of newly formed immature woven bone was higher in laser-treated sites (P = 0.24). On day 3, laser-treated sites showed significantly higher osteocalcin mRNA expression (P = 0.04) and PCNA-positive cell numbers (P = 0.01).

CONCLUSION

HiFP low-level diode laser irradiation enhanced soft- and hard-tissue healing of tooth extraction sockets. Lasers Surg. Med. 48:955-964, 2016. © 2016 Wiley Periodicals, Inc.

The effect of laser therapy on the expression of osteocalcin and osteopontin after tooth extraction in rats treated with zoledronate and dexamethasone

PURPOSE

Laser therapy has been used for the prevention and management of medication-related ostenecrosis of the jaw (MRONJ). The aim of this paper was to investigate the action of laser therapy on extraction socket healing in rats in conditions at risk for MRONJ, evaluating the expression of markers of bone metabolism.

METHODS

Thirty male Sprague-Dawley rats were divided in four groups: control group (C, n = 5), laser group (L, n = 5), treatment group (T, n = 10), and treatment plus laser group (T + L, n = 10). Rats of group T and T + L received zoledronate 0.1 mg/kg and dexamethasone 1 mg/kg every 2 days for 10 weeks. Rats of group C and L were infused with vehicle. After 9 weeks, the left maxillary molars were extracted in all rats. Rats of groups L and T + L received laser therapy (Nd:YAG, 1064 nm, 1.25 W, 15 Hz, 5 min, 14.37 J/cm(2)) in the socket area at days 0, 2, 4, and 6 after surgery. Western blot analysis was performed to evaluate the alveolar expression of osteopontin (OPN) and osteocalcin (OCN) 8 days after extraction.

RESULTS

Rats of groups L and T + L showed a significant higher expression of OCN compared to rats of groups C and T (+348 and +400 %, respectively; P = 0.013 and P = 0.002, respectively). The expression of OPN did not show significant differences among the different groups.

CONCLUSIONS

Our findings suggest that laser irradiation after tooth extraction can promote osteoblast differentiation, as demonstrated by the higher expression of OCN. Thus, laser irradiation could be considered a way to improve socket healing in conditions at risk for MRONJ development.

Photobiomodulation with low-level diode laser promotes osteoblast migration in an in vitro micro wound model

Laser photobiomodulation can improve bone healing, but well-defined treatment parameters are lacking. Saos-2 human osteoblast-like cells were subjected to an in vitro scratch-wound healing assay and irradiated by a 915-nm gallium-aluminum-arsenide diode laser for 0, 48, 96, and 144 s using doses of, respectively, 0, 5, 10, and 15 J/cm(2) . Wound area was measured after 4, 24, 48, and 72 h. Cell viability, DNA content, gene expression, and release of bone-related proteins were evaluated after 24, 48, and 72 h. Laser significantly improved wound healing compared with nonirradiated controls. Cells treated with laser doses of 5 and 10 J/cm(2) reached wound closure after 72 h, followed by 15 J/cm(2) after 96 h. With the cell proliferation inhibitor Mitomycin C, the doses of 10 and 15 J/cm(2) maintained an improved wound healing compared with controls. Laser increased collagen type 1 gene expression with higher doses inducing a longer-lasting effect, whereas transforming growth factor-beta 1 showed comparable or decreased levels in irradiated versus nonirradiated groups, with no effect on protein release. This study demonstrated that laser photobiomodulation at 915 nm promoted wound healing mainly through stimulation of cell migration and collagen deposition by osteoblasts.