Evaluation of the osteoinductive potential of implants and bioactive glass coated miniplates via electrolytic plasma oxidation in repair optimization bone in diabetic rats

Author(s)

Stéfany Barbosa

• Document type: Master's Dissertation
• Press: Araçatuba. 2023-02-28.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Odontologia. Araçatuba
• Defense date: 2023-02-17
• Advisor: Leonardo Perez Faverani

Abstract

Given the promising effects of bioglass on bone repair, this study aimed to evaluate the osteoinductive potential of the PEO-BG coating synthesized via oxidation by electrolytic plasma on new bone formation in diabetic rats. For this, implants of commercially pure titanium (Ticp) were coated with PEO-BG (~ 45.0 Si, 24.5 Ca, 24.5 Na, 6.0 P; m/v %) via PEO (500 V, 1000 Hz, duty cycle of 10 %, 420 sec). Initially, surface characterizations were conducted to confirm the topography (Confocal Laser Scanning Microscopy – CLSM), chemical composition (Energy Dispersive Spectroscopy – EDS) and physical-chemical properties (Prophylometry and Wetability) of the samples. Then, the in vivo study was conducted using Wistar rats (n = 27) and a protocol of induction of diabetes mellitus by administering streptozotocin (35mg/kg) was applied. After 30 days, the animals were randomly assigned to undergo surgery to implants placement or create femoral fractures, followed by fixation with miniplates of the 1.5mm system. The experimental groups were: Implant with commercially available surface of zirconia blasting followed by double acid etching (ZrAC group) and implant treated with PEO-BG (PEO-BG/Implant group) and for the plates, conventionally commercialized plates were used, with only machined surface (CONV group) and PEO-BG treated surface (PEO-BG/Board group). At 14 and 28 postoperative days, the animals were euthanized and the samples were lab processing for histometric and immunohistochemical (BMP-2, OPG, RANKL, and OCN) analysis, considering the level of significance of p<0.05 for the statistical analysis. The topographical characterizations demonstrated that the PEO-BG coating was successfully reproduced, with the effective incorporation of the bioglass elements, in addition to the formation of a surface with numerous roughness, high wettability and greater available surface area. Regarding the results, it is necessary to clarify that due to the condition of diabetes mellitus to which all the animals were submitted, there was a high incidence of infection in the surgical sites in the postoperative periods, even without suture dehiscence and the presence of external contaminants. Therefore, the plate samples were strongly affected by the infection and did not show tissue repair. Thus, it was not possible to consider such samples in the analysis and the positive points listed here refer only to samples from the study developed with implants. The decreasing in mineral bone density as a result of experimentally induced diabetes was proven from the biomechanical analysis, where diabetic animals had lower values of stiffness and maximum strength significantly compared to healthy animals (P<0.05). The implants data showed a greater newly formed bone and bone-implant contact for the PEO-BG group in both postoperative periods (14 and 28 days) (P<0.05), with an inflammatory profile compatible with the stages of tissue repair. BMP-2, RANKL, OPG and OCN immunolabeling corroborated the bone formation results and reinforced the understanding that PEO-BG optimized peri-implant bone repair. Microtomographic analysis demonstrated a significantly superior bone volume and percentage pattern for PEO-BG, as well as superior bone quality parameters. Thus, the PEO-BG coating effectively presented an osteoinductive activity and acted to improve the conditions of peri-implant bone repair, which it has great potential to favor the osseointegration of implants. (AU)

• FAPESP's process: 21/04001-8 - Evaluation of the osteoinductive potential of implants and miniplates with bioactive glass-based coating via electrolytic plasma oxidation in the optimization of bone repair in diabetic rats
• Grantee: Stefany Barbosa Alves da Cruz
• Support Opportunities: Scholarships in Brazil - Master