The investigations of the antibacterial actions, observed in ternary associations involving silver nanoparticles (AgNPs), chitosan and the antibiotics azithromycin (AZ), levofloxacin (LE) or tetracycline (TE), against Gram-negative and Gram-positive bacterial strains, were performed by in vitro antimicrobial susceptibility testing and checkerboard assays. The pH impact in the culture medium was carefully discarded, but preserving the best conditions for solubilizing chitosan. The synergistic antibacterial effects were observed in the most combinations of AgNPs, chitosan and antibiotic, leading to a reduction from 37 to 97% in the minimum inhibitory concentration of the drugs. The mechanisms for the enhanced antimicrobial effects were proposed based on the investigations of the adsorptions of the drugs on the silver surfaces through surface-enhanced Raman scattering (SERS) spectroscopy.

Fast curing biocompatible adhesives are a promising alternative to the metallic devices used for immobilization of fractures of small bone fragments as well as for some maxillofacial surgical procedures. They may serve as supports during the curing process, and present some advantages with respect to conventional fixation methods by plates and screws, such as their ease of application and the biodegradability of the material. The objective of the present study is to analyze the literature about bone adhesives based on cyanoacrylates, presenting the characteristics of these biomaterials, as well as their advantages and disadvantages for the fixation of small bone fragments in maxillofacial surgery and orthopedics. Study of the bioactivity, degradability, in vitro cytotoxicity, in vivo implantation and adhesiveness of the materials evaluated reveal their biocompatibility and their capacity to bind bone tissue.

Los adhesivos biocompatibles de curado rápido son una alternativa promisoria para sustituir los dispositivos metálicos empleados en la inmovilización de fracturas de pequeños fragmentos óseos y en algunos procedimientos de cirugía máxilo-facial. Ellos tienen la capacidad de servir de soporte en el proceso de curación, aportan ventajas respecto a los métodos convencionales de fijación mediante placas y tornillos, tales como: su facilidad de aplicación y la biodegradabilidad del material. El objetivo del presente trabajo es analizar la literatura relacionada con los adhesivos óseos basados en cianoacrilatos, exponiendo las características de estos biomateriales, sus ventajas y desventajas para la fijación de pequeños fragmentos óseos en cirugía máxilo facial y ortopedia. Los estudios realizados de bioactividad, degradabilidad, citotoxicidad in vitro, implantación in vivo y adhesividad han demostrado que los materiales evaluados son biocompatibles y capaces de unir el tejido óseo.

Calcium phosphate salts, or more specifically hydroxyapatite, are products of great interest in the fields of medical and dental science due to their biocompatibility and osteoconduction property. Deproteinized xenografts are primarily constituted of natural apatites, sintered or not. Variations in the industrial process may affect physicochemical properties and, therefore, the biological outcome. The purpose of this work was to characterize the physical and chemical properties of deproteinized xenogenic biomaterials, Bio-Oss (Geistlich Biomaterials, Wolhuser, Switzerland) and Gen-Ox (Baumer S.A., Brazil), widely used as bone grafts. Scanning electron microscopy, infrared region spectroscopy, X-ray diffraction, thermogravimetry and degradation analysis were conducted. The results show that both materials presented porous granules, composed of crystalline hydroxyapatite without apparent presence of other phases. Bio-Oss presented greater dissolution in Tris-HCl than Gen-Ox in the degradation test, possibly due to the low crystallinity and the presence of organic residues. In conclusion, both commercial materials are hydroxyapatite compounds, Bio-Oss being less crystalline than Gen-Ox and, therefore, more prone to degradation.

A sample of hydroxyapatite was synthesized and its crystalline structure was analyzed by X-ray diffraction by means of the Rietveld method. Two functions were used to fit the peak profiles, modified Voigt (TCHZ) and Pearson VII. The occupational factors and lattice parameters obtained by both models show that the sample does not contain relevant cationic substitutions. The interatomic distances from Ca1 to oxygens O1, O2 and O3 were adequate for a pure hydroxyapatite without defect at site Ca1. Besides, the use of multiple lines in planes (300) and (002) associated with the model Pearson VII resulted in good agreement with the TCHZ model with respect to the size-strain effectswith an ellipsoidal shape of crystallites. In conclusion, the procedures adopted in the synthesis of hydroxyapatite produced a pure and crystalline material. The experimental results of transmission electron microscopy confirmed the predicted shape of crystals.

A comparative study of two coating methods on titanium (Ti) substrates, sol-gel and electrophoresis processes, was performed. Before coating, two different surface treatments were employed. The hydroxyapatite (HA) powder were characterized by infrared spectroscopy (FTIR) and X-ray diffraction (XRD) while coated samples were examined by using scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS). Both techniques seem to be suitable to coat Ti. A previous surface treatment on metallic titanium seems to be fundamental to enhance coat uniformity and adhesion that was estimated by the adhesive tape test. The decrease in calcination temperature did not affect the coating adhesion.

Este estudo comparou in vivo a performance de implantes orais rosqueáveis fabricados em titânio comercialmente puro (Ti cp) e implantes recobertos com hidroxiapatita (HA) estequiométrica pelo processo de eletroforese. A camada recoberta foi caracterizada por microscopia eletrônica de varredura, espectroscopia de energia dispersiva e espectroscopia de infravermelho com transformada de Fourier. Foram obtidas camadas de carbonato-apatita bem aderidas ao substrato metálico, com espessura variando de 4 a 8 µm. Testes in vivo foram realizados por meio da inserção de implantes em tíbias de coelho por períodos de 8 ou 12 semanas. A análise histomorfométrica foi realizada quantificando-se imagens obtidas em microscopia eletrônica de varredura e com o auxílio de um software de processamento de imagens. Os resultados mostraram que a porcentagem de contato direto osso-implante foi significativamente maior para os implantes recobertos (p<0,05) do que para os implantes de titânio cp. A comparação da quantidade de osso no interior das roscas não mostrou diferença significativa para os dois tipos de implantes (p>0,05), embora os implantes de titânio cp tenham apresentado valores de porcentagem numericamente maiores que os implantes recobertos. Concluiu-se que os implantes recobertos com hidroxiapatita tiveram melhor performance em relação à área de contato osso-implante que os implantes de titânio cp. O processo de eletroforese parece ser uma alternativa simples e viável para se recobrir implantes de titânio com material osteocondutivo, como a hidroxiapatita.

This study compared in vivo the performances of commercially pure titanium (cp Ti) screw dental implants either uncoated or coated with synthetic hydroxyapatite (HA) by electrophoresis. The HA coating was characterized by scanning electron microscopy, energy dispersive spectroscopy (EDS) and Fourier-transform infrared (FT-IR) spectroscopy. Well-adhered carbonated-hydroxyapatite layers (4- to-8-µm-thick) were obtained. In vivo tests were carried out by insertion of both uncoated and HA-coated implants into rabbit tibiae for 8 or 12 weeks. Histomorphometric analysis was performed by scanning electron microscopy with the aid of image-processing software. Results showed significantly greater bone-implant contact for HA-coated implants (p<0.05) than cp Ti implants. Comparison of bone content inside the screw implants showed no significant differences (p>0.05) between both types of implants, although cp Ti had numerically higher percentage of bone content than HA-coated implants. In conclusion, the HA-coated implants had better performance regarding the bone-implant contact area than the uncoated implants; coating by electrophoresis proved to be a valuable process to coat metallic implants with an osteoconductive material such as hydroxyapatite.