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BACKGROUND: The ideal installation technique or implant macrogeometry for obtaining an adequate osseointegration in low-density bone tissue follows a challenge in the implantology. AIMS AND OBJECTIVE: The aim of the present study was to evaluate the behavior of three osteotomy techniques and two implant macrogeometries in two low-density polyurethane blocks. The insertion torque (IT), initial stability, pullout resistance, and weight of the residual bone material deposited on the implants were assessed. MATERIALS AND METHODS: A total of 120 implants with two different macrogeometries were used. They were divided into six groups according to the implant macrogeometry and the drilling technique performed (n = 20 implants per group). The implants were installed in polyurethane blocks with pounds per cubic foot (PCF) 10 and PCF 20 densities. The IT, initial stability, pullout resistance, and weight residual bone were measured. RESULTS: Differences were found in the values referring to the macrogeometry of the implants and the type of osteotomy performed. In all groups, the initial stability of the PCF 10 blocks was quite low. The undersized osteotomies significantly increased the values measured in all tests in the PCF 20 density blocks. CONCLUSIONS: In conclusion, even when a modified (undersized) osteotomy technique is used, implants inserted in low-quality bone (type IV) can present problems for osseointegration due their low initial stability and bone resistance. However, the modification in the implant macrogeometry (with healing chambers) presented more quantity of bone on the surface after the pullout test.

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Bone plays an important role in dental implant treatment success. The goal of this literature review is to analyze the influence of bone definition and finite element parameters on stress in dental implants and bone in numerical studies. A search was conducted of Pubmed, Science Direct and LILACS, and two independent reviewers performed the data extraction. The quality of the selected studies was assessed using the Cochrane Handbook tool for clinical trials. Seventeen studies were included. Titanium was the most commonly-used material in dental implants. The magnitude of the applied loads varied from 15 to 300 N with a mean of 182 N. Complete osseointegration was the most common boundary condition. Evidence from this review suggests that bone is commonly defined as an isotropic material, despite being an anisotropic tissue, and that it is analyzed as a ductile material, instead of as a fragile material. In addition, and in view of the data analyzed in this review, it can be concluded that there is no standardization for conducting finite element studies in the field of dentistry. Convergence criteria are only detailed in two of the studies included in this review, although they are a key factor in obtaining accurate results in numerical studies. It is therefore necessary to implement a methodology that indicates which parameters a numerical simulation must include, as well as how the results should be analyzed.

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Treatment for Chagas disease, a parasitosis caused by Trypanosoma cruzi, has always been based on two drugs, nifurtimox and benznidazole, despite the toxic side effects described after prolonged prescription. In this work, we study a new prospective antitrypanosomal drug based on vanadium, here named VIVO(5Brsal)(aminophen). We found a good IC50 value, (3.76 ± 0.08) µM, on CL Brener epimastigotes. The analysis of cell death mechanism allowed us to rule out the implication of a mechanism based on early apoptosis or necrosis. Recovery assays revealed a trypanostatic effect, accompanied by cell shape and motility alterations. An uptake mostly associated with the insoluble fraction of the parasites was deduced through vanadium determinations. Concordantly, no drastic changes of the parasite transcriptome were detected after 6 h of treatment. Instead, proteomic analysis uncovered the modulation of proteins involved in different processes such as energy and redox metabolism, transport systems, detoxifying pathways, ribosomal protein synthesis, and proteasome protein degradation. Overall, the results here presented lead us to propose that VIVO(5Brsal)(aminophen) exerts a trypanostatic effect on T. cruzi affecting parasite insoluble proteins.

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PURPOSE: The goal of this study was to foresee the fatigue life of two implant connections, evaluate the failure probability with several bone levels, and compare the in vitro test results with finite element results. MATERIALS AND METHODS: Mechanical tests were done with 60 implants (Ø3.50 mm), and abutments were used. These implants were divided into two groups with 30 implants each: internal hexagon and Morse taper. Three bone levels and 10 implants for each level were analyzed. The first level was considered at the platform level, the second at 3 mm, and the last level at 5 mm above the platform resin. A quasi-static loading at 30 degrees was applied to the axis of the implant in a universal machine. Six models were created and assembled to reproduce the conditions used in the laboratory testing. All models had restricted all displacement at the bone (bottom and lateral). Loads employed in the numerical test were obtained experimentally. Loads and material properties were supposed to be random. Then, failure probability was calculated by the probabilistic methodology. RESULTS: The internal hexagon group obtained the following mean fracture strengths: 2,092 N at the first level, 1,041 N at the second level, and 898 N at the third level. The mean fracture strengths for the Morse taper group were as follows: 1,687 N at the first level, 1,644 N at the second level, and 1,159 N at the third level. Results obtained by the finite element analysis are in accordance with the in vitro mechanical test results. The Morse taper group obtained a better behavior at bone levels 2 and 3 than the internal hexagon group. An important dependency between failure probability and bone level was found in the internal hexagon group. However, a similar behavior in levels 2 and 3 was obtained for the Morse taper group. CONCLUSION: In view of the mechanical results, the Morse taper group has a better behavior in bone levels 2 and 3 than the internal hexagon group. This is also in accordance with the probabilistic fatigue outcomes.

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The aim of this study was to fully characterize the mechanical behavior of an external hexagonal implant connection (ø3.5 mm, 10-mm length) with an in vitro study, a three-dimensional finite element analysis, and a probabilistic fatigue study. Ten implant-abutment assemblies were randomly divided into two groups, five were subjected to a fracture test to obtain the maximum fracture load, and the remaining were exposed to a fatigue test with 360,000 cycles of 150 ± 10 N. After mechanical cycling, all samples were attached to the torque-testing machine and the removal torque was measured in Newton centimeters. A finite element analysis (FEA) was then executed in ANSYS® to verify all results obtained in the mechanical tests. Finally, due to the randomness of the fatigue phenomenon, a probabilistic fatigue model was computed to obtain the probability of failure associated with each cycle load. FEA demonstrated that the fracture corresponded with a maximum stress of 2454 MPa obtained in the in vitro fracture test. Mean life was verified by the three methods. Results obtained by the FEA, the in vitro test, and the probabilistic approaches were in accordance. Under these conditions, no mechanical etiology failure is expected to occur up to 100,000 cycles. Graphical abstract ᅟ.

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Objectives: The objective of this study was to evaluate new bone formation derived from freshly crushed extracted teeth, grafted immediately in post-extraction sites in an animal model, compared with sites without graft filling, evaluated at 30 and 90 days. Material and Methods: The bilateral premolars P2, P3, P4 and the first mandibular molar were extracted atraumatically from six Beagle dogs. The clean, dry teeth were ground immediately using the Smart Dentin Grinder. The tooth particles obtained were subsequently sieved through a special sorting filter into two compartments; the upper container isolating particles over 1200 μm, the lower container isolated particles over 300 μm. The crushed teeth were grafted into the post-extraction sockets at P3, P4 and M1 (test group) (larger and smaller post-extraction alveoli), while P2 sites were left unfilled and acted as a control group. Tissue healing and bone formation were evaluated by histological and histomorphometric analysis after 30 and 90 days. Results: At 30 days, test site bone formation was greater in the test group than the control group (p < 0.05); less immature bone was observed in the test group (25.71%) than the control group (55.98%). At 90 days, significant differences in bone formation were found with more in the test group than the control group. No significant differences were found in new bone formation when comparing the small and large alveoli post-extraction sites. Conclusions: Tooth particles extracted from dog’s teeth, grafted immediately after extractions can be considered a suitable biomaterial for socket preservation.

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BACKGROUND: The topographical surficial characteristics and properties of materials can induce different cell reactions regarding the viability and adhesion according to the recent patents. The aim of this in vitro experimental study was to evaluate the viability and adhesion of fibroblastic cells seeded on titanium disks with different surface topography. In addition, we revised all patents related to surface treatment of dental implants. METHODS: Fibroblast cells were cultured on 6 surface models: mA disks corresponding to titanium surfaces without additional treatment (machined surface) were compared with mB disks, where surfaces were sandblasting etching using aluminum oxide; mC disks where titanium oxide was used for sandblasting etching; mD disks where triple acid conditioning was used; mE disks with laser treated surface; and mF disks which were made of titanium powder by a sintering process. Different surfaces were analyzed using an optical laser profilometer and SEM analysis. To evaluate cell viability on different disc surfaces, a fibroblast cell line derived from monkey kidney (VERO) was in vitro cultured on treated disks surface and cell viability assays were performed to compare growth of fibroblastic cells. Then, the adhesion of the cells was tested by washing procedure. RESULTS: The disks mA, mB, mC and mD less pronounced rugosities were observed and, disc in the mE and mF disks displayed a deeper pronounced surface. The cell viability and adhesion analysis showed significant higher levels on titanium disks surface obtained by the mF method. CONCLUSION: Our analysis showed that the surface morphology of titanium disc, independent of the roughness parameters, affects cell viability and adhesion differentially, since a higher percentage of viable and attached cells were observed on the mF disks in comparison with the other evaluated surfaces.

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OBJECTIVE: The aim of this study was to compare, through biomechanical and histological analysis, the aluminium (AlO2) and titanium dioxide (TiO2) microparticles for blasting during the sandblasting acid surface treatment in titanium dental implants using a rabbit tibia model. MATERIALS AND METHODS: Forty-eight commercially available titanium dental implants were divided into two test groups (n = 24 per group): implants with surface treated by AlO2 followed by acid etching as control group (Con group) and implants with surface treated by TiO2 followed by acid etching as test group (Test group). The implants were randomly installed in both tibias of eight rabbits and block samples were removed 4 and 8 weeks after implantation. Resonance Frequency Analyses were performed immediately after the implantation and at 8 weeks. Twelve implants of each group were removed to measure the reverse torque. The remaining implants were used for histological analysis. The data were compared using statistical tests (α = 0.05). RESULTS: In comparing the implant stability quotient at the two time points, no significant statistical differences were found (P > 0.05), as well as in the removal torque test at 8 weeks after implant placement, no found significant difference between the two groups was tested. Histomorphometric analysis showed a high degree of bone organization in all samples with no significant difference between groups in the bone-to-implant contact (P > 0.05). CONCLUSION: Within the limitations of this study, the results indicate that the media of surface blasting (AlO2 or TiO2 microparticles) did not show significant differences in the tested parameters for assessing the osseointegration of the implants.

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OBJECTIVE: The aim of this study was to evaluate a new design of the cervical portion of dental implant with the objective to increase the volume of peri-implant tissues in the crestal area. MATERIALS AND METHODS: Forty-eight tapered dental titanium implants with internal conical connection were implanted in healed alveolar sites of six dogs. Twenty-four conventional implants design (C1 implant) formed the control group, and 24 new implant design (V3 implant) formed the test group. The groups were randomized. Histological, histomorphometric, and implant stability quotient were performed. After 12 weeks of healing period, histomorphometric analyses of the specimens were carried out to measure the crestal bone level values and the tissue thickness in the cervical implant portion. The data were compared using statistical tests (α = 5%). RESULTS: The mean of the measurements in the buccal and lingual aspects measured of crestal bone level was 0.31 ± 0.24 mm and 0.30 ± 0.19 mm in the control group, respectively, and 0.71 ± 0.28 and 0.42 ± 0.30 mm in the test group, respectively, whereas the mean of the tissue thickness was 1.63 ± 0.33 mm and 2.04 ± 0.23 mm in the control group, respectively, and 2.11 ± 0.35 mm and 2.51 ± 0.41 mm in the test group. CONCLUSIONS: Within the limitations of this study, our findings suggest that more thickness of peri-implant hard and soft tissues may be expected in this new implant design. However, the control group with traditional implant design was found to have more height values of the crestal bone compared with new V3 implants.

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Some studies have demonstrated that in vivo degradation processes are influenced by the material's physico-chemical properties. The present study compares two hydroxyapatites manufactured on an industrial scale, deproteinized at low and high temperatures, and how physico-chemical properties can influence the mineral degradation process of material performance in bone biopsies retrieved six months after maxillary sinus augmentation. Residual biomaterial particles were examined by field scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) to determine the composition and degree of degradation of the bone graft substitute material. According to the EDX analysis, the Ca/P ratio significantly lowered in the residual biomaterial (1.08 ± 0.32) compared to the initial composition (2.22 ± 0.08) for the low-temperature sintered group, which also presented high porosity, low crystallinity, low density, a large surface area, poor stability, and a high resorption rate compared to the high-temperature sintered material. This demonstrates that variations in the physico-chemical properties of bone substitute material clearly influence the degradation process. Further studies are needed to determine whether the resorption of deproteinized bone particles proceeds slowly enough to allow sufficient time for bone maturation to occur.

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Detailed information about graft material characteristic is crucial to evaluate their clinical outcomes. The present study evaluates the physico-chemical characteristics of two xenografts manufactured on an industrial scale deproteinized at different temperatures (non-sintered and sintered) in accordance with a protocol previously used in sinus lift procedures. It compares how the physico-chemical properties influence the material's performance in vivo by a histomorphometric study in retrieved bone biopsies following maxillary sinus augmentation in 10 clinical cases. An X-ray diffraction analysis revealed the typical structure of hydroxyapatite (HA) for both materials. Both xenografts were porous and exhibited intraparticle pores. Strong differences were observed in terms of porosity, crystallinity, and calcium/phosphate. Histomorphometric measurements on the bone biopsies showed statistically significant differences. The physic-chemical assessment of both xenografts, made in accordance with the protocol developed on an industrial scale, confirmed that these products present excellent biocompatibilitity, with similar characteristics to natural bone. The sintered HA xenografts exhibited greater osteoconductivity, but were not completely resorbable (30.80 ± 0.88% residual material). The non-sintered HA xenografts induced about 25.92 ± 1.61% of new bone and a high level of degradation after six months of implantation. Differences in the physico-chemical characteristics found between the two HA xenografts determined a different behavior for this material.

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The aim of the present study was to monitor implant stability after sinus floor elevation with two biomaterials during the first six months of healing by resonance frequency analysis (RFA), and how physico-chemical properties affect the implant stability quotient (ISQ) at the placement and healing sites. Bilateral maxillary sinus augmentation was performed in 10 patients in a split-mouth design using a bobine HA (BBM) as a control and porcine HA (PBM). Six months after sinus lifting, 60 implants were placed in the posterior maxilla. The ISQ was recorded on the day of surgery from RFA at T1 (baseline), T2 (three months), and T3 (six months). Statistically significant differences were found in the ISQ values during the evaluation period. The ISQ (baseline) was 63.8 ± 2.97 for BBM and 62.6 ± 2.11 for PBM. The ISQ (T2) was ~73.5 ± 4.21 and 67 ± 4.99, respectively. The ISQ (T3) was ~74.65 ± 2.93 and 72.9 ± 2.63, respectively. All of the used HAs provide osseointegration and statistical increases in the ISQ at baseline, T2 and T3 (follow-up), respectively. The BBM, sintered at high temperature with high crystallinity and low porosity, presented higher stability, which demonstrates that variations in the physico-chemical properties of a bone substitute material clearly influence implant stability.

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This study aimed to investigate the processing parameters and biocompatibility of a novel biphasic dicalcium silicate (C2S) cement. Biphasic α´L + ß-C2Sss was synthesized by solid-state processing, and was used as a raw material to prepare the cement. In vitro bioactivity and biocompatibility studies were assessed by soaking the cement samples in simulated body fluid (SBF) and human adipose stem cell cultures. Two critical-sized defects of 6 mm Ø were created in 15 NZ tibias. A porous cement made of the high temperature forms of C2S, with a low phosphorous substitution level, was produced. An apatite-like layer covered the cement's surface after soaking in SBF. The cell attachment test showed that α´L + ß-C2Sss supported cells sticking and spreading after 24 h of culture. The cement paste (55.86 ± 0.23) obtained higher bone-to-implant contact (BIC) percentage values (better quality, closer contact) in the histomorphometric analysis, and defect closure was significant compared to the control group (plastic). The residual material volume of the porous cement was 35.42 ± 2.08% of the initial value. The highest BIC and bone formation percentages were obtained on day 60. These results suggest that the cement paste is advantageous for initial bone regeneration.

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The aim of this study was to predict the fatigue life of two different connections of a dental implant as in load transfer to bone. Two three-dimensional models were created and assembled. All models were subjected to a natural masticatory force of 118 N in the angle of 75° to the occlusal plane. All degrees of freedom in the inferior border of the cortical bone were restrained, and the mesial and distal borders of the end of the bone section were constrained. Fatigue material data and loads were assumed as random variables. Maximum principal stresses on bone were evaluated. Then, the probability of failure was obtained by the probabilistic approach. The maximum principal stress distribution predicted in the cortical and trabecular bone is 32 MPa for external connection and 39 MPa for internal connection. A mean life of 103 and 210 million cycles were obtained for external and internal connection, respectively. Probability cumulative function was also evaluated for both connection types. This stochastic model employs a cumulative damage model and probabilistic finite element method. This methodology allows the possibility of measured uncertainties and has a good precision on the results.

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OBJECTIVES: The aim of this study was to perform a histomorphometric and biomechanical comparison of three implants with different designs of the apical area to promote a better bone initial stability and its correlation with the osseointegration. MATERIAL AND METHODS: Fifty-four tapered implants with same length, diameter and surface properties but with three different apical configurations (Group I: MK4: Group II: C1 and Group III: MK7) were inserted in the tibia of rabbits. Implant stability and bone formation were evaluated by resonance frequency analysis measured at 0, 6, 8 and 12 weeks and by histomorphometric analysis performed at 6, 8 and 12 weeks. RESULTS: Statistical test to compare the stability through the implant stability quotient in the four times showed few differences between the groups and time periods proposed, with significance set at P < 0.05. In the bone-implant contact, by comparing the groups in the three times proposed, it was possible concluded that there is a similar behavior among the three implant design (P < 0.05). CONCLUSION: With the limitations of this animal study, it can be concluded that the design of the apical area influences the implant stability and the bone-to-implant contact.

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The high success range obtained with the implant-supported restorations has improved its applicability on routine of the daily clinical practice. This elevated percentage of success is related to the previous pre-clinical data obtained from animal and in vitro studies that evaluated the impact of implant surface topographies on bone tissue. However, the histological evaluation of human bone tissue is scarce. Therefore, the aim of this review is to depict an actual panorama of the data available on boneto- implant contact (BIC) of retrieved implants from human jaws. Some aspects of implant surface topography as well as systemic conditions as osteoporosis and smoking habit were demonstrated to have a strong impact, suggesting that the data obtained from human bone tissue is still valuable for the better understanding of the osseointegration process. This article also highlighted that most data in humans are difficult to interpret, due to the lack of detailed information about the surfaces found in retrieved implants. Without the definition of the surface characteristics, it is difficult to link exactly the surface patterns to specific clinical observations, and all observations remain de facto incomplete. As a conclusion, data from implants retrieved from human jaws are very important for our understanding, however the studies remain scarce and data is fragmented. This important approach should be improved, completed and developed in the future.

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BACKGROUND: Sinus elevation is a reliable and often-used technique. Success of implants placed in such situations, even with bone substitutes alone, prompted the authors of this study to strive for bone loss close to zero and research variables that cause higher or lower rates of resorption. The objective of this study is to evaluate survival rates and marginal bone loss (MBL) around implants placed in sites treated with maxillary sinus augmentation using anorganic bovine bone (ABB), and identify surgical and prosthetic prognostic variables. METHODS: Fifty-five implants were placed in 30 grafted maxillary sinuses in 24 patients. Periapical radiographs were evaluated immediately after implant placement (baseline), 6 months, and at the most recent follow-up. MBL was calculated from the difference between initial and final measurements, taking into account a distortion rate for each radiograph compared with original implant measurements. RESULTS: Survival rate was 98.2%, with only one implant lost (100% survival rate after loading) over a mean follow-up time of 2.0 ± 0.9 years. MBL ranged from 0 to 2.85 mm: 75.9% of mesial sites and 83.4% of distal sites showed <1 mm of MBL, whereas 35.2% of mesial sites and 37% of distal sites exhibited no bone loss. MBL was significantly (P <0.05) greater in open-flap compared with flapless surgery. CONCLUSIONS: Within the limitations of the present study, it was concluded that maxillary sinus elevation with 100% ABB gives predictable results, and that flapless surgery results in less MBL compared with traditional open-flap surgery.

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The aim of this study was to compare the influence of graft material (non-ceramic hydroxyapatite versus autologous bone) on bone behaviour and perform a resonance frequency analysis of implants placed in augmented sites to evaluate stability. For this study, 11 patients with bilateral edentulous areas in the mandibular posterior region were selected. Alveolar augmentation osteotomies were bilaterally (split mouth design) performed. In one hemiarch, the space generated by the osteotomy was grafted with an interpositional intra-oral autologous bone graft (control group). In the other hemiarch, the space generated by the osteotomy was grafted with an interpositional non-ceramic hydroxyapatite (ncHA) (test group). The groups were randomized. After 6 months of healing, a bone sample was retrieved from each side for histological evaluation using a trephine drill that was 2-mm in internal diameter. The implant stability quotient (ISQ) was measured by the resonance frequency immediately following implant placement at baseline and after 6 months of follow-up. Good incorporation of the graft was observed in both groups; however, in the test group, a residual-grafted material was observed. Bone density and marrow spaces were similar between groups. Correlations between the ISQ values and the histometric variables were not observed (p>0.05). The results of this trial suggest that both intra-oral autologous bone and ncHA may be elected as interpositional grafting materials to vertically augment posterior atrophic mandibles.

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The establishment of the subgingival microbiota is dependent on successive colonization of the implant surface by bacterial species. Different implant surface topographies could influence the bacterial adsorption and therefore jeopardize the implant survival. This study evaluated the biofilm formation capacity of five oral streptococci species on two titanium surface topographies. In vitro biofilm formation was induced on 30 titanium discs divided in two groups: sandblasted acid-etched (SAE- n = 15) and as-machined (M- n = 15) surface. The specimens were immersed in sterilized whole human unstimulated saliva and then in fresh bacterial culture with five oral streptococci species: Streptococcus sanguinis, Streptococcus salivarius, Streptococcus mutans, Streptococcus sobrinus, and Streptococcus cricetus. The specimens were fixed and stained and the adsorbed dye was measured. Surface characterization was performed by atomic force and scanning electron microscopy. Surface and microbiologic data were analyzed by Student's t-test and two-way ANOVA, respectively (P < 0.05). S. cricetus, S. mutans, and S. sobrinus exhibited higher biofilm formation and no differences were observed between surfaces analyzed within each species (P > 0.05). S. sanguinis exhibited similar behavior to form biofilm on both implant surface topographies, while S. salivarius showed the lowest ability to form biofilm. It was concluded that biofilm formation on titanium surfaces depends on surface topography and species involved.

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The fascicular composition and organisation of the inferior alveolar nerve (IAN) were determined to confirm the microarchitecture of the IAN bundles into each of the mandibular teeth, including the composition of the mental nerve. The aim of this study was to evaluate peripheral nerve repair after the application of an antioxidant compound to the damaged nerve tissue to elevate the concentration and bioavailability of elements capable of favouring tissue repair. Twenty-five Wistar rats were divided into groups: The Control 1 (Ctl 1) (n = 5) animals had the ischiatic nerve exposed with no suture injury and were sacrificed at 30 days post-operatively. The Control 2 (Ctl 2) (n = 10) animals had the ischiatic nerve exposed, and the nerve was injured using suture in three distinct regions. In the experimental (Exp) animals (n = 10), an antioxidant organic compound was applied to the nerve injury site. The animals with nerve injury (Ctl2 and Exp group) were sacrificed at 15 and 30 days post-operatively. The histological analysis showed less degeneration in the Exp group at 15 and 30 days post-operatively. Nerve neoformation forming a connection between the distal and proximal suture sites was observed in the experimental group. This study presented an alternative to nerve repair using an antioxidant compound.

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