There are several treatment methods available for bone repair, although the effectiveness becomes limited in cases of large defects. The objective of this pre-clinical protocol was to evaluate the grafting of hydroxyapatite/tricalcium phosphate (BCP) ceramic biomaterial (B; QualyBone BCP®, QualyLive, Amadora, Portugal) together with the heterologous fibrin biopolymer (FB; CEVAP/UNESP Botucatu, Brazil) and with photobiomodulation (PBM; Laserpulse®, Ibramed, Amparo, Brazil) in the repair process of bone defects. Fifty-six rats were randomly divided into four groups of seven animals each: the biomaterial group (G1/B), the biomaterial plus FB group (G2/BFB); the biomaterial plus PBM group (G3/B + PBM), and the biomaterial plus FB plus PBM group (G4/BFB + PBM). After anesthesia, a critical defect was performed in the center of the rats’ parietal bones, then filled and treated according to their respective groups. The rats were euthanized at 14 and 42 postoperative days. Histomorphologically, at 42 days, the G4/BFB + PBM group showed a more advanced maturation transition, with more organized and mature bone areas forming concentric lamellae. A birefringence analysis of collagen fibers also showed a more advanced degree of maturation for the G4/BFB + PBM group. In the comparison between the groups, in the two experimental periods (14 and 42 days), in relation to the percentage of formation of new bone tissue, a significant difference was found between all groups (G1/B (5.42 ± 1.12; 21.49 ± 4.74), G2/BFB (5.00 ± 0.94; 21.77 ± 2.83), G3/B + PBM (12.65 ± 1.78; 29.29 ± 2.93), and G4/BFB + PBM (12.65 ± 2.32; 31.38 ± 2.89)). It was concluded that the use of PBM with low-level laser therapy (LLLT) positively interfered in the repair process of bone defects previously filled with the biocomplex formed by the heterologous fibrin biopolymer associated with the synthetic ceramic of hydroxyapatite and tricalcium phosphate.
There are numerous conflicting discussions about the outbreak of the new coronavirus . This letter to the editor presents some anatomical and physiological considerations regarding one of the symptoms reported by patients: the loss or reduction of smell, based on recent descriptions and studies, and aims to stimulate knowledge and debate on this topic.
Extending the range of use of the heterologous fibrin biopolymer, this pre-clinical study showed a new proportionality of its components directed to the formation of scaffold with a lower density of the resulting mesh to facilitate the infiltration of bone cells, and combined with therapy by laser photobiomodulation, in order to accelerate the repair process and decrease the morphofunctional recovery time. Thus, a transoperative protocol of laser photobiomodulation (L) was evaluated in critical bone defects filled with deproteinized bovine bone particles (P) associated with heterologous fibrin biopolymer (HF). The groups were: BCL (blood clot + laser); HF; HFL; PHF (P+HF); PHFL (P+HF+L). Microtomographically, bone volume (BV) at 14 days, was higher in the PHF and PHFL groups (10.45 ± 3.31 mm3 and 9.94 ± 1.51 mm3), significantly increasing in the BCL, HFL and PHFL groups. Histologically, in all experimental groups, the defects were not reestablished either in the external cortical bone or in the epidural, occurring only in partial bone repair. At 42 days, the bone area (BA) increased in all groups, being significantly higher in the laser-treated groups. The quantification of bone collagen fibers showed that the percentage of collagen fibers in the bone tissue was similar between the groups for each experimental period, but significantly higher at 42 days (35.71 ± 6.89%) compared to 14 days (18.94 ± 6.86%). It can be concluded that the results of the present study denote potential effects of laser radiation capable of inducing functional bone regeneration, through the synergistic combination of biomaterials and the new ratio of heterologous fibrin biopolymer components (1:1:1) was able to make the resulting fibrin mesh less dense and susceptible to cellular permeability. Thus, the best fibrinogen concentration should be evaluated to find the ideal heterologous fibrin scaffold.
In an attempt to achieve greater therapeutic effi ciency of products, especially in the pharmacological area such as drugs in general, the drug delivery system that controls the distribution of substances through macromolecular carriers has been developed with the primary objective of optimizing their delivery to target locations [1]. Records in the scientifi c literature of pioneering controlled drug delivery studies date back to the 1960s at Harvard with the in vivo implantation of a silicone tube that became a drug delivery device, in this case anesthetic gases, at a constant rate of release. [2]. Clinical use was approved in the 1980s and 1990s with the use of microscopic degradable polymer depot Drug Delivery Systems (DDS) but it can be cited that clinical success occurred in the 2000s with nanoscopic products [3]. From this period a rapid evolution occurred and the range of use at both molecular and supramolecular levels was expanded [4]. The clinical use of nanotechnology in health has been a major revolution, with controlled drug release being one of its examples in treating various types of cancer, manufacturing vaccines and treating fungal infections using liposomes as a component [5].
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