Effect of topographical modification treatments of zirconia on topography, microstructure, and bacterial adhesion
Nowadays, the material’s choice for dental implants is increasingly shifting towards zirconia-based ones. Indeed, 3 mol.% yttria stabilized zirconia (3Y-TZP) is recognized as an excellent choice due to its good mechanical properties, aesthetic advantages, and biocompatibility with the human body. Ne...
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| Tipo de recurso: | tesis de maestría |
| Fecha de publicación: | 2024 |
| País: | España |
| Institución: | Universitat Politècnica de Catalunya (UPC) |
| Repositorio: | UPCommons. Portal del coneixement obert de la UPC |
| Idioma: | inglés |
| OAI Identifier: | oai:upcommons.upc.edu:2117/405724 |
| Acceso en línea: | https://hdl.handle.net/2117/405724 |
| Access Level: | acceso abierto |
| Palabra clave: | Zirconium Dental implants Zirconia dental implants bacterial adhesion topographical modification Zirconi Implants dentals Àrees temàtiques de la UPC::Enginyeria dels materials |
| Sumario: | Nowadays, the material’s choice for dental implants is increasingly shifting towards zirconia-based ones. Indeed, 3 mol.% yttria stabilized zirconia (3Y-TZP) is recognized as an excellent choice due to its good mechanical properties, aesthetic advantages, and biocompatibility with the human body. Nevertheless, in terms of biological success, it is essential to avoid bacterial infections around the implant and to promote its osseointegration. On this sense, it is well known that the topography of implants strongly influences cell response, which are essential for osseointegration, as well as the bacteria adhesion. Numerous studies have been conducted on this subject, particularly focusing on the modification of surface topography, which significantly impacts the biological properties of dental implants. Various strategies have been used to modify the surface of zirconia, from which laser patterning and chemical etching treatment can be highlighted. Nevertheless, surface treatment can also induce damages and defects that alter the mechanical properties and influence the aging of the zirconia implant. The main goal of this master thesis is to investigate the combination of laser patterning and chemical etching modifications on zirconia and evaluate the effects on the physicochemical properties, microstructure and the antibacterial potential. The samples were prepared through Cold Isostatic Pressing and sintered at 1450 °C. The surface modification process began with the laser treatment, in which a femtosecond (fs-) laser was used to create 3µm periodic linear and grid patterns. This was followed by chemical etching, using a hydrofluoric acid (HF) solution with a concentration of 40% during 1 h. The etching treatment was applied on polished zirconia, and on some of the linear and grid patterns, to evaluate the effects of laser treatment alone, etching alone, and the combination of both. Subsequently, the changes in the topography, wettability, and microstructure were investigated through a series of characterization techniques. This included scanning electron microscopy (SEM) for examining morphology and surface damage; confocal laser scanning microscopy (CLSM) for analyzing the surface roughness and other relevant topographical patterns; X-ray diffraction (XRD) and confocalRAMAN spectroscopy for assessing phase transformation; and measuring the water contact angle to determine the wettability of the samples. Furthermore, a bacteria adhesion study was conducted to assess the response of S. aureus bacteria to the modified surfaces after 4 hours of incubation. This involved counting the number of adherent bacteria on each sample using live/dead staining and CLSM. Then, bacteria adhesion and morphology were further examined by SEM. The results from the topographical characterization indicated that the fs- laser treatment created welldefined and periodic linear and grid patterns, with a depth of approximately 1µm and a periodicity of 3µm, and surface damage in the forms of nanocracks inside of the valleys. In contrast, acid etching resulted in a uniformly nano-rough surface with numerous pits. When both treatments were combined, the laser patterns were almost eliminated, but the roughness was higher than the other samples. XRD and Raman analysis revealed first, that all the treatments slightly increase the monoclinic phase volume (Vm) (%), secondly, only a small layer of grains below the surface is transformed and finally, the distribution of Vm (%) over the surface is non-homogeneous. Furthermore, wettability measurements revealed increased hydrophobicity in all samples using the Wenzel model. Finally, biological characterization results showed a significant decrease in bacterial adhesion on all treated samples, particularly on the ones that underwent only acid-etched treatment. Finally, all the treated surfaces increased the roughness and allowed a reduction of adherent bacteria onto the surface but the combination of laser patterning and chemical etching did not increase the bacteria reduction when compared to the treatments alone. |
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