Bovine Bone Matrix Action Associated With Morphogenetic Protein in Bone Defects in Rats Submitted to Alcoholism

Extended excessive alcohol use causes changes in bone tissue, thus affecting osteogenesis. The objective of this study was to evaluate if demineralized bone matrix (Gen-ox (R)) associated with bone morphogenetic protein (Gen-pro (R)) changes bone neoformation in rats submitted to experimental alcoholism. Forty male rats (Rattus norvegicus) were separated into 2 groups of 20 animals each: Group E1, which received ethyl alcohol at 25% and had the surgical cavity filled in only with blood clot; and Group E2. which received ethyl alcohol at 25% and had the surgical cavity filled in with demineralized bovine cortical bone associated with bone morphogenetic protein. The animals were submitted to a three-week period of gradual adaptation to alcohol, and then continued receiving alcohol at 25% for 90 days, when the surgical cavity was made. After the surgery, the animals continued consuming alcohol until reaching the sacrifice periods of 10, 20, 40, and 60 days, when the tibias were removed for histological processing. Results showed that surgical cavity repair and bone marrow reorganization occurred faster in Group E1 than in Group E2. At the end of the experiment, it was observed that animals in Group E2 had thick bony trabeculae surrounding the implanted material particles and a small area of connective tissue in the surface region. In conclusion, the implanted material did not accelerate bone neoformation, rather it served as a structure for osteogenesis.

Exploring anorganic bovine bone granules as osteoblast carriers for bone bioengineering: a study in rat critical-size calvarial defects

It is known that current trends on bone bioengineering seek ideal scaffolds and explore innovative methods to restore tissue function. In this way, the objective of this study was to evaluate the behavior of anorganic bovine bone as osteoblast carrier in critical-size calvarial defects. MC3T3-E1 osteoblast cells (1x10(5) cells/well) were cultured on granules of anorganic bovine bone in 24-well plates and after 24 h these granules were implanted into rat critical-size calvarial defects (group Biomaterial + Cells). In addition, other groups were established with different fillings of the defect: Blood Clot (negative control); Autogenous Bone (positive control); Biomaterial (only granules) and Cells (only MC3T3-E1 cells). After 30 days, the animals were euthanized and the calvaria were technically processed in order to allow histological and morphometric analysis. It was possible to detect blood vessels, connective tissue and newly formed bone in all groups. Particularly in the Biomaterial + Cells group, it was possible to observe a profile of biological events between the positive control group (autogenous bone) and the group in which only anorganic bovine granules were implanted. Altogether, the results of the present study showed that granules of anorganic bovine bone can be used as carrier to osteoblasts and that adding growth factors at the moment of implantation should maximize these results.

Biological monitoring of a promissory xenogenic pin for biomedical applications: a preliminary intraosseous study in rats

Objectives: Over the last years, it is known that in some cases metal devices for biomedical applications present some disadvantages suggesting absorbable materials (natural or synthetic) as an alternative of choice. Here, our goal was to evaluate the biological response of a xenogenic pin, derived from bovine cortical bone, intraosseously implanted in the femur of rats. Material and methods: After 10, 14, 30 and 60 days from implantation, the animals (n = 5/period) were killed and the femurs carefully collected and dissected out under histological demands. For identifying the osteoclastogenesis level at 60 days, we performed the immunohistochemisty approach using antibody against RANKL. Results: Interestingly, our results showed that the incidence of neutrophils and leukocytes was observed only at the beginning (10 days). Clear evidences of pin degradation by host cells started at 14 days and it was more intensive at 60 days, when we detected the majority of the presence of giant multinucleated cells, which were very similar to osteoclast cells contacting the implanted pin. To check osteoclastogenesis at 60 days, we evaluated RANKL expression and it was positive for those resident multinucleated cells while a new bone deposition was verified surrounding the pins in all evaluated periods. Conclusions: Altogether, our results showed that pins from fully processed bovine bone are biocompatible and absorbable, allowing bone neoformation and it is a promissory device for biomedical applications.

Comparative analysis of Enterococcus Faecalis biofilm formation on different substrates

Introduction: The aim of this study was to compare Enterococcus faecalis biofilm formation on different substrates. Methods: Cell culture plates containing growth medium and E. faecalis (ATCC 29212) were used to grow biofilm on bovine dentin, gutta-percha, hydroxyapatite, or bovine bone. Substrates were incubated at 37 C for 14 or 21 days, and the medium was changed every 48 hours. After the growth induction periods, specimens (n = 5 per group and per induction period) were stained by using Live/Dead, and the images were analyzed under a confocal microscope. The total biovolume (mm3), live bacteria biovolume (mm3), and substrate coverage (%) were quantified by using the BioImage_L software. Results obtained were analyzed by nonparametric tests (P = .05). Results: Biofilm formation was observed in all groups. Gutta-percha had the lowest total biovolume at 14 days (P < .05) and hydroxyapatite the highest at 21 days (P < .05). No significant difference was observed in green biovolume at 14 days. At 21 days, however, hydroxyapatite had the highest volume (P < .05). The percentages of coverage were similar among all substrates at 21 days (P > .05), but at 14 days, bovine bone presented the highest coverage (P < .05). Conclusions: E. faecalis was capable of forming biofilm on all substrates during both growth periods; hydroxyapatite presented the highest rates of biofilm formation. The type of substrate influenced the biofilm characteristics, according to the parameters evaluated

The Behavior of Demineralized Bone Matrix (DBM) in Post-Extraction Sockets

Autogenous bone grafts are considered to be the gold standard in bone regeneration because of their osteogenic activity; however, due to limited availability of intraoral donor sites and the need to resolve the demands of patients requires an alternative to these. Two male patients were submitted to implant surgery in two stages with 6 months intervals between each of them: the first was exodontia and placement of DBM graft into the socket; the second stage was the drill with a 2 mm internal diameter trephine in center of the alveolar ridge previously grafted with DBM and subsequent implant placement. The samples were analyzed under histological techniques. A very mature bone was observed at 6 months after DBM graft placement in the sockets, showing it to be a good alternative as bone graft.

Long-term rabbits bone response to titanium implants in the presence of inorganic bovine-derived graft

This study evaluated bone responses to titanium implants in the presence of an inorganic graft material. The bilateral mandible incisors of 24 rabbits were surgically extracted and one of the exposed sockets, chosen at random, was filled with an inorganic xenogenic bone graft (Gen-ox (R)), whereas the remaining socket was left to heal naturally and served as a control. After 60 days, titanium implants were inserted in the specific areas, and on days 0, 30, 60, and 180 after the implant insertions, six animals of each group were killed. Digital periapical radiography of implant region was obtained and vertical bone height (VBH) and bone density (BD) were evaluated by digital analysis system. In the undecalcified tissue cuts, bone-to-implant contact (BIC) and bone area (BA) within the limits of the implant threads were evaluated and compared statistically by means of two-way ANOVA and Tukey's test (rho < 0.05). No significant differences were detected in VBH and BA, either between groups or between different experimental intervals. The BD was significantly higher in the experimental group than in the control group in all the intervals tested, but there were no significant differences by interval. The BIC was statistically lower in the control group on day 0; however, a significant increase was observed on days 60 and 180 (rho < 0.05). The use of an inorganic xenograft prior to insertion of a titanium implant did not interfere with the course of osseointegration.

Influence of effective number of pulses on the morphological structure of teeth and bovine femur after femtosecond laser ablation

Femtosecond lasers have been widely used in laser surgery as an instrument for contact-free tissue removal of hard dental, restorative materials, and osseous tissues, complementing conventional drilling or cutting tools. In order to obtain a laser system that provides an ablation efficiency comparable to mechanical instruments, the laser pulse rate must be maximal without causing thermal damage. The aim of this study was to compare the different morphological characteristics of the hard tissue after exposure to lasers operating in the femtosecond pulse regime. Two different kinds of samples were irradiated: dentin from human extracted teeth and bovine femur samples. Different procedures were applied, while paying special care to preserving the structures. The incubation factor S was calculated to be 0.788 +/- 0.004 for the bovine femur bone. These results indicate that the incubation effect is still substantial during the femtosecond laser ablation of hard tissues. The plasma-induced ablation has reduced side effects, i.e., we observe less thermal and mechanical damage when using a superficial femtosecond laser irradiation close to the threshold conditions. In the femtosecond regime, the morphology characteristics of the cavity were strongly influenced by the change of the effective number of pulses. (C) 2012 Society of Photo-Optical Instrumentation Engineers (SPIE). [DOI: 10.1117/1.JBO.17.4.048001]

INFLUENCE OF CORTICAL BONE THICKNESS ON THE ULTRASOUND VELOCITY

Objective: An experimental in vitro study was carried out to evaluate the influence of cortical bone thickness on ultrasound propagation velocity. Methods: Sixty bone plates were used, made from bovine femurs, with thickness ranging from 1 to 6 mm (10 of each). The ultrasound velocity measurements were performed using a device specially designed for this purpose, in an underwater acoustic tank and with direct contact using contact gel. The transducers were positioned in two ways: on opposite sides, with the bone between them, for the transverse measurement; and parallel to each other, on the same side of the bone plates, for the axial measurements. Results: In the axial transmission mode, the ultrasound velocity speed increased with cortical bone thickness, regardless of the distance between the transducers, up to a thickness of 5 mm, then remained constant thereafter. There were no changes in velocity when the transverse measures were made. Conclusion: Ultrasound velocity increased with cortical bone thickness in the axial transmission mode, until the thickness surpasses the wavelength, after which point it remained constant. Level of Evidence: Experimental Study.