Influence of the λ780nm laser light on the repair of surgical bone defects grafted or not with biphasic synthetic micro-granular hydroxylapatite+Beta-Calcium triphosphate

Nociceptive and histomorphometric evaluation of the effects of ozone therapy on the rat masseter muscle in a carrageenan model of myofascial pain

OBJECTIVE

This study evaluated the effects of intramuscular ozone therapy on nociception, inflammation, and tissue damage caused by the injection of carrageenan in the masseter muscle of rats.

DESIGN

Rat masseter muscles were injected with saline or carrageenan. Seventy-seven adult male rats were divided into six groups: Sal, saline; Car, carrageenan; Ibup + Sal, ibuprofen and saline; Ibup + Car, ibuprofen and carrageenan; O3 + Sal, ozone and saline; and O3 + Car, ozone and carrageenan. The mixture of 5% ozone and 95% oxygen (20 µg/mL) was administered three times in the course of a week. Nociceptive responses in the masseter muscles were measured using a head withdrawal threshold, determined by an electronic von Frey anesthesiometer. The animals were euthanized one or eight days after the carrageenan injection, and the masseters were submitted to histological and histomorphometric analyses.

RESULTS

Mechanical allodynia and inflammation levels were reduced in the Ibup + Car group compared to the other groups. Myonecrosis was similar among carrageenan-treated groups. Picrosirius red stained sections showed more collagen fibers and more regenerating myofibers in the O3 + Car group compared to the other groups. Eight days after carrageenan injection, the O3 + Car group showed neutrophils close to the regenerating myofibers.

CONCLUSIONS

Intramuscular ozone therapy did not alleviate mechanical allodynia, and it did not protect the masseter muscle against the deleterious effects produced by carrageenan, probably due to the mode of administration of this therapeutic agent.

Effect of different low-level intensity laser therapy (LLLT) irradiation protocols on the osseointegration of implants placed in grafted areas

OBJECTIVE

To evaluate the effect of different protocols of low-level intensity laser therapy (LLLT) irradiation on the osseointegration of implants placed in grafted areas.

METHODOLOGY

84 rats were randomly allocated into six groups: DBB: defect filled with deproteinized bovine bone; HA/TCP: defect filled with biphasic ceramic of hydroxyapatite/β-tricalcium phosphate ; DBB-LI: defect filled with DBB and treated with LLLT after implant placement; HA/TCP-LI: defect filled with HA/TCP and treated with LLLT after implant placement; DBB-LIB: defect filled with DBB and treated with LLLT after graft procedure and implant placement; and HA/TCP-LIB: defect filled HA/TCP and treated with LLLT after graft procedure and implant placement. The bone defects were made in the tibia and they were grafted. After 60 days, the implants were placed. The rats were subsequently subjected to euthanasia 15 and 45 days after implant placement. The pattern of osseointegration and bone repair in the grafted area was evaluated by biomechanical, microtomographic, and histometric analyses. Furthermore, the expression of bone biomarker proteins was assessed.

RESULTS

The LLLT groups presented higher removal torque, mineralized tissue volume, and a greater degree of osseointegration, especially when LLLT was performed only after implant placement, and these findings were associated with higher expression of BMP2 and alkaline phosphatase.

CONCLUSION

LLLT performed on implants placed in grafted areas enhances the osseointegration process.

Bone substitutes and photobiomodulation in bone regeneration: A systematic review in animal experimental studies

In general, bone fractures are able of healing by itself. However, in critical situations such as large bone defects, poor blood supply or even infections, the biological capacity of repair can be impaired, resulting in a delay of the consolidation process or even in non-union fractures. Thus, technologies able of improving the process of bone regeneration are of high demand. In this context, ceramic biomaterials-based bone substitutes and photobiomodulation (PBM) have been emerging as promising alternatives. Thus, the present study performed a systematic review targeting to analyze studies in the literature which investigated the effects of the association of ceramic based bone substitutes and PBM in the process of bone healing using animal models of bone defects. The search was conducted from March and April of 2019 in PubMed, Web of Science and Scopus databases. After the eligibility analyses, 16 studies were included in this review. The results showed that the most common material used was hydroxyapatite (HA) followed by Biosilicate associated with infrared PBM. Furthermore, 75% of the studies demonstrated positive effects to stimulate bone regeneration from association of ceramic biomaterials and PBM. All studies used low-level laser therapy (LLLT) device and the most studies used LLLT infrared. The evidence synthesis was moderate for all experimental studies for the variable histological analysis demonstrating the efficacy of techniques on the process of bone repair stimulation. In conclusion, this review demonstrates that the association of ceramic biomaterials and PBM presented positive effects for bone repair in experimental models of bone defects.

Effects of photobiomodulation on bone defects grafted with bone substitutes: A systematic review of in vivo animal studies

A present, photobiomodulation therapy (PBMT) effectiveness in enhancing bone regeneration in bone defects grafted with or without biomaterials is unclear. This systematic review (PROSPERO, ref. CRD 42019148959) aimed to critically appraise animal in vivo published data and present the efficacy of PBMT and its potential synergistic effects on grafted bone defects. MEDLINE, CCCT, Scopus, Science Direct, Google Scholar, EMBASE, EBSCO were searched, utilizing the following keywords: bone repair; low-level laser therapy; LLLT; light emitting diode; LEDs; photobiomodulation therapy; in vivo animal studies, bone substitutes, to identify studies between 1994 and 2019. After applying the eligibility criteria, 38 papers included where the results reported according to "PRISMA." The results revealed insufficient and incomplete PBM parameters, however, the outcomes with or without biomaterials have positive effects on bone healing. In conclusion, in vivo animal studies with a standardized protocol to elucidate the effects of PBMT on biomaterials are required initially prior to clinical studies.

Evaluation of the Effects of Low-Level Laser Therapy on Diabetic Bone Healing

The aim of the present study was to evaluate the effects of low-level laser therapy (LLLT) and biphasic alloplastic bone graft material on diabetic bone healing. Induction of diabetes was performed in 14 male Sprague-Dawley rats by intraperitoneal injection of a 50 mg/kg dose of streptozotocin. Two bilaterally symmetrical non-critical-sized bone defects were created in the parietal bones in each rat. Right defects were filled with biphasic alloplastic bone graft. Rats were randomly divided into 2 groups, with 1 group receiving 10 sessions of LLLT (GaAlAs, 78.5 J/cm, 100mW, 0.028 cm beam). The LLLT was started immediately after surgery and once every 3 days during postoperative period. At the end of treatment period, new bone formation and osteoblast density were determined using histomorphometry. Empty (control), graft-filled, LLLT-treated and both graft-filled and LLLT-treated bone defects were compared. New bone formation was higher in the graft treatment samples compared with the control (P = 0.009) and laser samples (P = 0.029). In addition, graft-laser combination treatment samples revealed higher bone formation than control (P = 0.008) and laser (P = 0.026) samples. Osteoblast density was significantly higher in the laser treatment (P <0.001), graft treatment (P = 0.001) and graft-laser combination treatment (P <0.001) samples than control samples. In addition, significantly higher osteoblast density was observed in the graft-laser combination treatment samples compared to the graft treatment samples (P = 0.005). The LLLT was effective to stimulate osteoblastogenesis but failed to increase bone formation. Graft augmentation for treatment of bone defects seems essential for proper bone healing in diabetes, regeneration may be supported by the LLLT to enhance osteoblastogenesis.

Repair of surgical bone defects grafted with hydroxylapatite + β-TCP combined with hyaluronic acid and collagen membrane in rabbits: A histological study

Objectives

This study aimed to assess the repair of bone defects with or without grafts using biphasic synthetic micro-granular hyaluronic acid (HA) with β-TCP and bovine type I collagen (Osteon II Collagen) with or without either hyaluronic acid or a collagen membrane in surgically created bone defects in the tibia of rabbits.

Methods

Fifteen male rabbits were divided into 3 groups, each with 5 rabbits. Two bone defects were made in each tibia. In the right tibia, the defects were either filled with clot as a control or grafted with Osteon II Collagen and hyaluronic acid. In the left tibia, the other two defects were filled with Osteon II Collagen alone or with Osteon II Collagen and a collagen membrane. The specimens were observed one, two, and four weeks after surgery. Histological examinations were used to evaluate the degree of healing according to the amount of newly formed bone.

Results

The combination of the bone grafting biomaterial with hyaluronic acid was found to develop into the most advanced stages of the bone repair process at the second and fourth week only (p ≤ 0.05), compared to the biomaterial with a collagen membrane, as well as the other groups. On the other hand, the biomaterial in combination with a collagen membrane showed significantly more bone formation than the biomaterial alone or the control group by the fourth week.

Conclusions

The local application of hyaluronic acid and collagen membranes made a greater contribution to the bone repair process in the tibia of rabbits than the bone graft substitute (Osteon II Collagen) alone.

Does laser phototherapy influence the proliferation of myoepithelial cells in the salivary gland of hypothyroid rats?

Thyroid hormones influence both development and growth of organs and tissues and guarantee metabolic demands that interfere with the quality of digestive secretions, including those of the salivary glands. Laser phototherapy - LPT can modulate various biological phenomena and its diverse effects permit the action on different cell types. The aim of this study was to evaluate the influence of laser phototherapy on myoepithelial cells of salivary glands of hypothyroid rats. Forty-two albino Wistar rats were divided into two main groups: euthyroid (EU) and hypothyroid (HYPO). Hypothyroidism was induced using propylthiouracil (PTU) for 4weeks. Each group was divided into subgroups: control (without laser) and laser groups (Red/infrared - IR). LPT was used on the submandibular gland and was carried out using a diode laser (λ660 or λ780nm, 40mW, spot size 0.04cm², irradiation area 1cm², 300s, 6J/cm² per gland, 12J/cm² per session) and started two weeks after PTU treatment. LPT was repeated every other day for two weeks. After animal death, the glands were removed, dissected and processed for immunohistochemical analysis. It was observed an increase in the number of myoepithelial cells of hypothyroid control rats in comparison to euthyroid controls (p=0.001). Visible LPT (λ660nm) caused significant higher proliferation of myoepithelial cells in EU rats when compared to IR LPT (λ 780nm)(p≤0.001).It is concluded that, despite the LPT protocol used did not influence myoepithelial proliferation on hypothyroid rats it significantly increased the proliferation on euthyroid animals.

Low-level laser therapy (780 nm) combined with collagen sponge scaffold promotes repair of rat cranial critical-size defects and increases TGF-β, FGF-2, OPG/RANK and osteocalcin expression

The aim of this study was to evaluate the effect of collagen sponge scaffold (CSS) implantation associated with low-level laser therapy (LLLT) on repairing bone defects. A single 5-mm cranial defect was surgically created in forty Wistar rats, which then received one of the following four interventions (n = 10 per group): no treatment (G0); bone defect implanted with collagen sponge scaffold (CSS) alone (G1); defect treated with low-level laser therapy (LLLT) (wavelength 780 nm; total energy density 120 J/cm² ; power 50 mW) alone (G2); and CSS associated with LLLT treatment (G3). After surgery, animals in each group were euthanized at 21 days and 30 days (n = 5 per euthanasia time group). Bone formation was monitored by X-ray imaging analysis. Biopsies were collected and processed for histological analysis and immunohistochemical evaluation of transforming growth factor-beta (TGF-β), fibroblast growth factor-2 (FGF-2), osteoprotegerin (OPG) and receptor activator of nuclear factor ƙ (RANK). Osteocalcin (OCN) was detected by immunofluorescence analysis. Compared to the G0 group, defects in the 30-day G3 group exhibited increased bone formation, both by increase in radiopaque areas (P < 0.01) and by histomorphometric analysis (P < 0.001). The histopathological analysis showed a decreased number of inflammatory cells (P < 0.001). The combined CCS + LLLT (G3) treatment also resulted in the most intense immunostaining for OPG, RANK, FGF-2 and TGF-β, and the most intense and diffuse OCN immunofluorescent labelling at 30 days postsurgery (G3 vs. G0 group, P < 0.05). Therefore, the use of CCS associated with LLLT could offer a synergistic advantage in improving the healing of bone fractures.

Low-level laser therapy improves bone formation: stereology findings for osteoporosis in rat model

Low-level laser therapy (LLLT) benefits bone metabolism, but its use needs to be standardized. We evaluated the effects of LLLT on bone defects in calvaria of ovariectomized rats. Stereology was used to calculate tissue repair volume (V tr ), density of trabecular bone volume (Vv t ), total volume of newly formed trabecular bone (Vtot), and the area occupied by collagen fibers (A C ). Fifty-four Wistar rats were submitted to bilateral ovariectomy, and bone defects were created in calvaria after 150 days. The animals were divided into nine groups (n = 6), and 24 h after defects, the treatment started with a 780-nm low-intensity GaAlAs laser: G1, G2, and G3 received 3 sessions of 0, 20, and 30 J/cm(2) respectively; G4, G5, and G6 received 6 sessions of 0, 20, and 30 J/cm(2), respectively; and G7, G8, and G9 received 12 sessions of 0, 20, and 30 J/cm(2), respectively. A normal distribution was found for all of the data. The test used to verify the normality was the Kolmogorov-Smirnov (KS, p > 0.05). The one-way ANOVA followed by Tukey's post hoc test was used for data processing. A difference of p < 0.05 was considered statistically significant. Groups G2 and G1 showed significance for V tr , Vv t , Vtot, and (A C ). Results were significant for (Vv t ) and (Vtot) between G3 and G1. There were no significant results between G5 and G4 as well as between G8 and G7. Groups G6 and G4 results showed statistical difference for V tr , Vv t , Vtot, and (A C ). Groups G9 and G7 showed significance for V tr , Vv t , Vtot, and (A C ). In conclusion, there was new bone formation in the groups that received 20 and 30 J/cm(2) when compared to control groups, but over time, the dose of 30 J/cm(2) showed better stereological parameters when compared to 20 J/cm(2).

Repair of Surgical Bone Defects Grafted with Hydroxylapatite + β-TCP and Irradiated with λ=850 nm LED Light

The treatment of bone loss due to different etiologic factors is difficult and many techniques aim to improve the repair, including a wide range of biomaterials and recently, photobioengineering. This work aimed to assess by histological analysis the repair of bone defects grafted with biphasic synthetic micro-granular HA + β-TCP associated with LED phototherapy. Forty rats were divided into 4 groups (Clot, LED, Biomaterial and LED + Biomaterial) each subdivided into 2 subgroups according to the time of animal death (15 and 30 days). Surgical bone defects were prepared on the femur of each animal with a trephine drill. In animals of the Clot group the defect was filled only by blood clot, in the LED group the defect filled with the clot was further irradiated. In the animals of Biomaterial and LED + Biomaterial groups the defect was filled by biomaterial and the last one was further irradiated (λ=850±10 nm, 150 mW, Φ ~ 0.5 cm2, 20 J/cm2 - session, 140 J/cm2- treatment) at 48-h intervals for 2 weeks. Following animal death, samples were taken and analyzed by light microscopy. Using the degree of maturation of the bone by assessment of the deposition/organization of the basophilic lines in the newly formed bone tissue, the LED + Biomaterial group was the one in a more advanced stage of bone repair process at the end of the experiment. It may be concluded that the use of LED phototherapy was effective in positively modulating the process of bone repair of bone defects in the femur of rats submitted or not to biomaterial grafting.