The Effect of Photobiomodulation Therapy in Different Doses on Bone Repair of Critical Size Defects in Rats: A Histomorphometric Study

Abstract

Introduction: Photobiomodulation therapy (PBM) appears to induce osteogenesis and stimulate fracture repair; because of its capacity, it is considered a promising treatment, but the characteristics of response to different radiation doses must be investigated through in vivo studies to establish their safety and effectiveness. Thus, this paper aims to analyze the effects of the PBM at different doses on the repair of critical bone defects through histological and histomorphometric analyses. Methods: Sixty 90-day-old adult rats (Rattus norvegicus, albinus, Wistar) weighing approximately 300 g were used. Critical bone defects of 5 mm in diameter were performed in their calvaria. The animals were randomly separated into 5 groups: C-Blood clot, L15-PBM 15J/cm2 , L30-PBM 30 J/ cm2 , L45-PBM 45 J/cm2 , L60-PBM 60 J/cm2 . Each group was subdivided according to observation periods of 30 and 60 days with 6 rats in each subgroup. Low-level gallium aluminum arsenide (GaAlAs) lasers were used at a 660 nm wavelength, 30 mW and 0.04 cm2 in area. The PBM was applied over 5 points; 4 points of application were distributed on the edges while one point of application was located in the center of the bone defect. PBM occurred right after the procedure. In 30 and 60 days, the animals were euthanized by anesthesia overdose and the analyses were performed. The data were analyzed statistically by the ANOVA, together with the Tukey test, whose significance level was 5%. Results: As regards the treatment factor, the highest percentage of bone neoformation was achieved by group L45-60. The group with the highest closure, despite not having a statistically significant difference with the other doses, was 45 J with only 0.49 mm between edges. Conclusion: Thus, the present study allowed concluding that the highest percentage of bone neoformation area was achieved at 45 J/cm2 in 60 days; that is, it was significantly effective in comparison with other doses.

Effects of a Biocomplex Formed by Two Scaffold Biomaterials, Hydroxyapatite/Tricalcium Phosphate Ceramic and Fibrin Biopolymer, with Photobiomodulation, on Bone Repair

“…The increasing bone formation observed over time in this research was also reported in studies that used similar methodologies [ 20 , 44 ]. These data demonstrate that PBM may have positive effects on bone tissue, improving the quality and density of newly formed bone [ 44 , 46 , 47 ].…”

“…The histological data also showed positive effects regarding the combination of treatment methods in the bone regeneration process, which was already visible at 14 postoperative days. In this period of analysis, it is possible to observe the presence of vascular sprouts in the G4/BFB + PBM group, which may be due to the effects of PBM therapy on the local microcirculation [ 46 ]. In addition to PBM, the fibrin biopolymer also contributed to stimulate angiogenic factors and neovascularization, as observed in previous studies [ 20 , 44 ].…”

Protective Effect of Photobiomodulation against Hydrogen Peroxide-Induced Oxidative Damage by Promoting Autophagy through Inhibition of PI3K/AKT/mTOR Pathway in MC3T3-E1 Cells

“…With the gradual exploration of PBM, many researchers have investigated the role of PBM in osteoblasts and found that PBM can significantly facilitate multiplication of MC3T3-E1 cells [ 29 ]. De Marco et al suggested that PBM could improve fracture healing in rats and promote bone regeneration in bone defects [ 30 ]. Other studies have suggested that different wavelengths of PBM have significant regulatory effects on osteoblast differentiation [ 14 ].…”

Use of Photobiomodulation Combined with Fibrin Sealant and Bone Substitute Improving the Bone Repair of Critical Defects

“…In recent years, innovative modalities, such as low-intensity pulsed ultrasound, photobiomodulation therapy (PBMT) with low-level laser, and hyperbaric oxygen therapy, or their combination, are being evaluated in an attempt to improve metabolism and accelerate the bone repair process [ 19 , 20 , 21 , 22 ]. Photobiomodulation has been shown to be capable of biostimulation of bone cells during in vitro or in vivo studies [ 23 , 24 , 25 ]. The most accepted hypothesis in relation to the mechanism of action is that monochromatic laser photons activate chromophores in the cell’s cytochrome C oxidase, resulting in accelerated cellular activity, increased ATP and alkaline phosphatase (ALP) concentrations, and calcium release [ 25 , 26 ].…”

“…Photobiomodulation has been shown to be capable of biostimulation of bone cells during in vitro or in vivo studies [ 23 , 24 , 25 ]. The most accepted hypothesis in relation to the mechanism of action is that monochromatic laser photons activate chromophores in the cell’s cytochrome C oxidase, resulting in accelerated cellular activity, increased ATP and alkaline phosphatase (ALP) concentrations, and calcium release [ 25 , 26 ].…”