Effects of low-level laser therapy on changes in inflammation and in the activity of osteoblasts in the expanded premaxillary suture in an ovariectomized rat model

Therapeutic Effect of a Low-Level Laser on Acute Pain and Post-operative Mouth Opening After Closed Reduction of Mandibular-Condylar Fracture

Introduction: The purpose of this study was to determine the therapeutic effect of low-level laser therapy (LLLT) on acute pain and the range of mouth opening after condylar closed reduction surgery. The use of low-level lasers, especially to reduce inflammation and pain, has received more attention in recent years. The results of many studies performed in this field are contradictory, and the effectiveness of low-level lasers in the treatment of patients is still uncertain. Methods: This study was performed as a randomized, double-blinded clinical trial on 40 patients with condylar closed reduction surgery. Patients were randomly assigned to two groups of 20 patients, including the placebo and intervention groups. In the intervention group, the patients received LLLT (100 mw, 2 J/cm², 20 S/point, 14 extraoral points, 7 days). The range of jaw movements after opening the intermaxillary-fixation was measured. Patients' pain was assessed using the visual analog scale (VAS). Data were analyzed using SPSS software version 21, the chi-square test, and repeated measures ANOVA. Results: There was no significant difference between the study groups in terms of the range of jaw motions. The mean VAS score was 56.85 (SD=3.817) in the intervention group and 60.95 (SD=4.861) in the placebo group, showing a statistically significant difference between the two groups at the end of the study (P=0.007) Conclusion: The results of this study indicated the effectiveness of low-level lasers in reducing acute pain in patients undergoing closed condylar surgery. Iranian Registry of Clinical Trials (IRCT20200520047519N1).

Response of osteoblastic cells to low-level laser treatment: a systematic review

Low-level laser therapy (LLLT)-induced photobiomodulation (PBM) stimulates bone tissue regeneration by inducing osteoblast differentiation and mitochondrial activation. However, the role of reactive oxygen species (ROS) in this process remains controversial. The aim of this systematic review was to collect and analyze the available literature on the cellular and molecular effects of LLLT on osteoblasts and the role of ROS in this process. A search was conducted in PubMed, ScienceDirect, Scopus, and Web of Science. Studies published in English over the past 15 years were selected. Fourteen articles were included with moderate (n = 9) and low risk of bias (n = 5). Thirteen studies reported the use of diode lasers with wavelengths (λ) between 635 and 980 nm. One study used an Nd:YAG laser (λ1064 nm). The most commonly used λ values were 808 and 635 nm. The energy densities ranged from 0.378 to 78.75 J/cm², and irradiation times from 1.5 to 300 s. Most studies found increases in proliferation, ATP synthesis, mitochondrial activity, and osteoblastic differentiation related to moderate and dose-dependent increases in intracellular ROS levels. Only two studies reported no significant changes. The data presented heterogeneity owing to the variety of LLLT protocols. Although several studies have shown a positive role of ROS in the induction of proliferation, migration, and differentiation of different cell types, further research is required to determine the specific role of ROS in the osteoblastic cell response and the molecular mechanisms involved in triggering previously reported cellular events.

Benefits of Using Low-level Laser Therapy in the Rapid Maxillary Expansion: A Systematic Review

Aim and objective

Determine the benefits of low-level laser therapy (LLLT) as a complement to rapid maxillary expansion (RME), through a systematic review.

Background

Transversal maxillary compression is a common skeletal problem that can be treated with different devices. This RME technique consists of the separation and regeneration of the midpalatal suture. Low-level laser therapy has been suggested to be able to accelerate bone healing after trauma or bone defects.

Review results

Thirty-two publications were found by electronic search during July to August of 2019 on Medline (PubMed) and Google Scholar, using the terms “Low-Level Laser”, “LLLT”, “Rapid Maxillary Expansion”, and “Osteogenesis Distraction”. Only 16 were used (2 systematic reviews, 6 articles on humans, and 8 on animals). Even though all the studies had different intervention protocols, they all revealed that LLLT has the effect of accelerating bone regeneration after RME.

Conclusion

The use of LLLT as a complement to RME has shown promising results with cellular biostimulation, promoting angiogenesis and bone regeneration of the midpalatal suture.

Clinical significance

This study provides scientific evidence of the benefits of using LLLT as a complement to RME during orthopedic and orthodontic treatments, accelerating bone regeneration and reducing the time of consolidation of the maxillary.

How to cite this article

Lai P-S, Fierro C, Bravo L, et al. Benefits of Using Low-level Laser Therapy in the Rapid Maxillary Expansion: A Systematic Review. Int J Clin Pediatr Dent 2021;14(S-1):S101–S106.

Parathyroid hormone promotes maxillary expansion and reduces relapse in the repeated activation maxillary expansion rat model by regulating Wnt/β-catenin pathway

Background

Constricted maxillary bone is a common skeletal deformity, which may lead to crowding and posterior crossbite. Mid-palatal suture expansion is often used to increase the maxillary width, but its skeletal effects are limited and tend to relapse, even with prolonged retention. We hypothesized that parathyroid hormone (PTH) may reduce the relapse of maxillary expansion.

Methods

We established a novel rat maxillary expansion model using palatal tubes with an insertable “W”-shaped spring which can be repeatedly activated. A total of 32 male healthy Wistar rats were randomly divided into six groups: the control group, the PTH group, the expansion group, the expansion + PTH group, the expansion + relapse group and the expansion + PTH + relapse group. All animals in the first 4 groups were killed after 10 days and the 2 relapse groups were killed after 15 days. The maxillary arch widths and histological staining were used to assess the expansion and relapse effects. The immunohistochemical staining, micro-CT, RT-qPCR and Western blot were used to evaluate the bone remodeling during expansion.

Results

The suture width was increased by the expansion device, and the repeated activation maxillary expansion rat model showed better expansion effects than the conventional model. PTH significantly promoted the expansion width and reduced the relapse ratio. Meanwhile, in the expansion + PTH group, histological and immunohistochemical staining showed that osteoblasts, osteoclasts, new cartilage and osteoid were significantly increased, micro-CT showed increased bone mass, and PCR and Western blot results confirmed up-regulation of RANKL, β-catenin, type II collagen and OCN.

Conclusion

The novel repeated activation maxillary expansion rat model has better effects than the conventional model. PTH enhances the maxillary expansion and reduces its relapse by regulating Wnt/β-catenin and RANKL pathways. PTH administration may serve as an adjunctive therapy in addition to mechanical expansion for treatment of maxillary constriction.

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.

The Effects of Photobiomodulation on MC3T3-E1 Cells via 630 nm and 810 nm Light-Emitting Diode

BACKGROUND Photobiomodulation (PBM) has been explored as a promising therapeutic strategy to regulate bone cell growth; however, the effects of PBM on osteoblast cell lines remains poorly understood. In addition, as a light source of PBM, the light uniformity of light-emitting diode (LED) devices has not been given enough attention. MATERIAL AND METHODS Here, we sought to investigate the effects of PBM on MC3T3-E1 cells via 630 nm and 810 nm light from a newly designed LED with high uniformity of light. Cell proliferation, flow cytometric analysis, alkaline phosphatase (ALP) staining, ALP activity, Alizarin Red S staining, and quantitative real-time polymerase chain reaction (qRT-PCR) were carried out to assess treatment response. MC3T3-E1 cells were irradiated with LED devices (630±5 nm and 810±10 nm, continuous wave) for 200 seconds at a power density of 5 mW/cm² once daily. RESULTS Increases in cell proliferation and decreases in cell apoptosis were evident following irradiation. ALP staining intensity and activity were also significantly increased following irradiation. Level of mineralization was obviously enhanced in irradiated groups compared with non-irradiated controls. qRT-PCR also showed significant increases in mRNA expression of osteocalcin (OCN) and osteoprotegerin (OPG) in the irradiated groups. CONCLUSIONS Our results showed that LED PBM could promote the proliferation, ALP staining intensity and activity, level of mineralization, gene expression of OCN and OPG of MC3T3-E1 cells, with no significant difference between the 630 nm- and 810 nm-irradiated groups.

Does laser therapy improve the wound healing process after tooth extraction? A systematic review

Laser therapy could amplify the oral wound healing process by stimulating cell regeneration after injury, attenuating pain, and modulating the immune system. The purpose of this systematic review was to evaluate whether the application of laser therapy improved alveolar healing after tooth extractions. Eight electronic databases were screened: MedLine (PubMed), The Cochrane Library, Web of Science, Scopus, Lilacs, Ibecs, Scielo, and BBO. Three reviewers independently assessed the title and abstracts of potentially relevant studies. Only clinical trials and animal experiments that evaluated the wound healing effect of laser therapy after tooth extraction were included. A total of 16 studies fulfilled all criteria, thus 8 animal experiments and 8 clinical trials were included. Different types of laser were evaluated, such as CO₂ , GaAlAs, Nd:YAG, Diode Laser, HeNe, and High-frequency Pulsed Diode Laser. Although HF, Diode and GaAs lasers were able to enhance wound healing process in clinical studies, four trials and one animal experiment showed no improvement in wound healing with laser therapy after tooth extractions. In general, the current available evidence in the literature showed that laser therapy improved the wound healing process, but these findings were limited to the type of laser applied and its specific settings. Further well-designed and randomized controlled trials are needed to support a benefit effect of using laser therapy after tooth extraction. PROSPERO registration number: CRD42014007509 (2014).

Titanium scaffold osteogenesis in healthy and osteoporotic rats is improved by the use of low-level laser therapy (GaAlAs)

The present study aimed to assess the effects of low-level laser therapy (GaAlAs) on the bone repair process within titanium scaffolds in the femurs of healthy and osteoporotic rats. Fifty-six rats were divided into four groups: group Sh: SHAM animals that received scaffolds; group LSh: SHAM animals that received scaffolds and were subjected to laser therapy; group OV: ovarietomized (OVX) animals that received scaffolds; and group LOV: OVX animals that received scaffolds and were subjected to laser therapy. Thirty days following ovariectomy or sham surgery, scaffolds were implanted in the left femurs of all animals in the study. Immediately after opening the surgical site, the inner part of the surgical cavity was stimulated with low-level laser (GaAlAs). In addition to this procedure, the laser group was also subjected to sessions of low-level laser therapy (LLLT) at 48-h intervals, with the first session performed immediately after surgery. The rats were sacrificed at 2 and 6 weeks, time in which femur fragments were submitted for histological and histomorphometric examination, and skin tissue above the scaffold was submitted to histological analysis. At the end of the study, greater bone formation was observed in the animals submitted to LLLT. At 2 and 6 weeks, statistically significant differences were observed between LSh and Sh groups (p = 0.009 and 0.0001) and LOV and OV (p = 0.0001 and 0.0001), respectively. No statistical difference was observed when assessing the estrogen variable. On the basis of our methodology and results, we conclude that LLLT improves and accelerates bone repair within titanium scaffolds in both ovariectomized and healthy rats, when compared to animals not subjected to radiation.

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.