Assessment of the LED phototherapy on femoral bone defects of ovariectomized rats: a Raman spectral study

Abstract

Osteoporosis is a disease characterized by the reduction of bone mineral density. LED wavelengths seem to have similar photo-stimulating effects to laser light. The aim of this study was to assess the Raman shifts: ∼ 960 (phosphate hydroxyapatite), ∼ 1,070 (carbonate hydroxyapatite), and ∼ 1,454 cm (-1) (lipids and proteins) on bone defects of ovariectomized rats treated or not with LED phototherapy (LED-PT). Thirty female rats were divided into four groups (Basal, OVX, OVX+Clot, and OVX+Clot+LED), then subdivided into two subgroups (15 and 30 days after surgery). Osteoporosis induction by ovariectomy (OVX) was performed in all groups, except for the normal basal group. Following development of osteoporosis, one surgical bone defect (5 mm(2)) was created on the femur of each animal. Defects were irradiated with LED light (λ = 850 ± 10 nm, P = 150 mW, CW, Ф = 0.5 cm(2), 20.4 J/cm(2) per session, t = 128 s, 163.2 J/cm(2) per treatment) at 48 h interval during 2 weeks. Raman measurements were taken at the surface of the defects 30 days after surgery. Significant difference between groups Basal, OVX+Clot, and OVX+Clot+LED for the peaks at ∼ 960 (p ≤ 0.001; 15 and 30 days), ∼ 1,070 (p ≤ 0.001; 15 and 30 days), and ∼ 1,450 cm(-1) (p = 0.002; 15 days; p = 0.004; 30 days) were detected. In addition, statistical differences were obtained between groups OVX, OVX+Clot, and OVX+Clot+LED for these same peaks at all time points (p ≤ 0.001). At 15 and 30 days, there were statistical differences between groups OVX+Clot and OVX+Clot+LED for the peaks at ∼ 960 (p ≤ 0.001), ∼ 1,070 (p ≤ 0.001; p = 0.003), and ∼ 1,450 cm(-1) (p ≤ 0.001; p = 0.002). The results of this study are indicative that infrared LED-PT improved the deposition of HA on bone defects of ovariectomized rats.

Phototherapy up-regulates dentin matrix proteins expression and synthesis by stem cells from human-exfoliated deciduous teeth

“…6 It has been reported that LED irradiation in the infrared range of the spectrum (from 700 nm to 1 mm wavelength) is able to pass through the dentin barrier 7 and photobiostimulate underlying cells, 8 increasing the cell viability and alkaline phosphatase activity of odontoblast-like cells as well as upregulating collagen type I (Col I) expression. 5,9,10 Additionally, infrared light can improve healing of bone defects mechanically created in rats 11 and reduce pain in temporomandibular disorders. 12 Based on these data, it is reasonable to consider that phototherapy technology with LED represents an interesting alternative for clinical application in restorative dentistry, particularly for stimulation of pulp cells subjacent to the cavity floor.…”

3rd Symposium of Lasers In Dentistry

“…We highlight the laser light used for laser phototherapy (LPT). Over the past 20 years, experimental protocols have been proposed for a considerable number of procedures involving bone repair in animals and humans [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. These protocols are now also used as an aid to an efficient repair of mineralized tissues, as LPT accelerates bone repair by directly affecting, in different ways, the new bone formation.…”

“…Fibroblast proliferation and its increased activity have been previously detected in individuals and cultures of irradiated cells and are responsible for the high concentration of collagen fibers observed in the irradiated bone. Our previous studies indicate that the effective result of LPT is observed when the treatment is performed in the initial stages of repair, when a large cell proliferation occurs [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Vascular responses to LPT have also been suggested as one of the possible mechanisms responsible for the positive clinical results observed.…”

“…Destacamos a luz laser usada para fototerapia a laser (FTL). Ao longo dos últimos 20 anos, protocolos experimentais foram propostos para um número considerável de procedimentos envolvendo a reparação do osso em animais e humanos [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Esses protocolos agora são usados também como auxílio para um reparo eficiente de tecidos mineralizados, pois a FTL acelera o reparo ósseo afetando diretamente, de diversas maneiras, a nova formação óssea.…”

“…A proliferação fibroblástica e a sua atividade aumentada foram detectadas anteriormente em indivíduos e culturas de células irradiadas e são responsáveis pela grande concentração de fibras de colágeno observadas no osso irradiado. Nossos estudos anteriores indicam que o resultado efetivo da FTL é observado quando o tratamento é realizado nos estágios iniciais do reparo, quando ocorre uma grande proliferação celular [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] A Terapia fotodinâmica (PDT) tem sido muito utilizada em Periodontia com o objetivo de promover a redução dos microrganismos periodontais principalmente como coadjuvante ao tratamento periodontal não cirúrgico e cirúrgico, ou para o tratamento de bolsas residuais [1]. Consiste no uso de compostos fotossensibilizadores excitados por luz com comprimento ressonante gerando espécies reativas de oxigênio que são citotóxicas para vários tipos de microrganismos Estudos experimentais em animais, tem demonstrado que a PDT isolada ou quando associada a terapia periodontal mecânica é capaz de controlar a perda óssea alveolar, reduzir a extensão do processo inflamatório e da progressão da doença periodontal, controlar a atividade osteoclastogênica, regulando o metabolismo ósseo e promovendo a redução de periodontopatógenos na periodontite experimentalmente induzida, tanto em animais normais [2,3] como em animais modificados sistemicamente [4,5,6].…”