E-glass fiber reinforced composite as an oral implant abutment material. In vitro bacterial adhesion assay and biomechanical tests

Resumen

E-glass fiber-reinforced composites (FRC) have become popular in dental and medical applications for load-bearing applications. This is due to their enhanced biomechanical matching with living tissues compared to traditional materials, as well as additional biocompatible properties. Recently, it has been shown that FRC enhances gingival soft tissue integration. Besides, satisfactory results have been observed after undergoing five years of simulated oral fatigue on unidirectionally reinforced FRC abutments. These studies make FRC promising materials for implant abutment applications. Nonetheless, there is a lack of studies regarding bacterial adhesion of FRC when compared with those published on traditional implant abutment materials. Furthermore, the effect of different fiber orientation on the load-bearing capacity of FRC abutments has yet to be determined. Therefore, this work aimed to evaluate E-glass FRC in terms of biological and mechanical aspects in order to explore a new alternative metal-free abutment material. A further aim has been to develop a standard set of surface analysis methods. Surface topography characterization was performed by using atomic force microscopy and white light interferometry. Wettability was determined by using the sessile drop method. Additionally, a novel standard set of surface parameters to characterize biomaterial surfaces was proposed taking into account their correlation values and sensitivity in material discrimination (Study I). The attachment (bacterial adhesion) of Escherichia coli and Staphylococcus aureus was determined and discussed (Study II). Finally, the mechanical properties were assessed by three-point bending tests and the load-bearing capacity examined using static loading following ISO 10477 and ISO 14801 standards (Study III). The results of the FRC surface characterization showed that they exhibited rough surfaces with hydrophobic characteristics. This increased roughness enhanced the early bacterial adhesion on FRC surfaces nevertheless, on the later, mature biofilm compensated these differences. The following parameters were best in biomaterials discrimination: Sa, Sku, and Smid at the nanoscale, Sa and Sz at the microscale and one contact angle. Bidirectionally reinforced FRC rods showed a greater breakage capacity compared to unidireccional rods. Bidirectionally reinforced FRC abutments showed statistically higher load-bearing capacities compared to unidirectionally reinforced abutments. Hence, owing to its comparable bacterial response to current implant abutment materials in addition to the adequate mechanical properties of bidirectional FRC abutments, it can be concluded that FRC is a promising alternative material in implant prosthetic dentistry.