Introduction: Despite of wide research on surface modifications of the titanium implants for bone contact applications, a relatively low number of works consider interaction between the titanium surfaces and soft tissues. However, this topic is of interest in several cases, such as the transmucosal dental and percutaneous orthopedic implants. The rationale of this research follows the following fundamental principles of surface engineering. Topography and roughness play a crucial role both in bacterial and cell adhesion, moreover specific chemical and biological stimuli can be sent to the cells in order to modulate the biological response to the implants. A lower Ra limit of 0.2 µm has been defined in literature in order to avoid an increased bacterial contamination [1]. In the case of soft tissues, fibroblasts preferentially adhere on polished substrates and can be guided by surface grooves [2]. Keratin has a well-known action of chemical stimulus on fibroblasts. On this basis, the specific aim of this research work is to modify titanium surfaces by means of nanogrooves and keratin nanofibers, in order to drive gingival fibroblasts alignment and proliferation through topographical and chemical stimuli without increasing bacterial adhesion. Material and Methods: Oriented nanogrooves were obtained on c.p. titanium by a mechanical route (specific polishing protocol) or by means of Electron Beam Welding (EBW) paying attention to keep the final surface roughness lower than 0.2 µm. Keratin was extracted from wool and nanofibers were deposited onto mirror polished or roughened titanium substrates by electrospinning both as fibers randomly oriented or aligned to the grooves. The viability and orientation of human gingival fibroblasts were investigated on the modified surfaces together with bacterial (S. aureus) adhesion and biofilm formation.Results and Discussion: Oriented nanogrooves (Ra 0.1-0.2 µm) were successfully obtained on titanium substrates both by mechanical and EBW routes. Keratin nanofibers were deposited on the titanium surfaces without significantly altering surface roughness and they resulted stable up to 1 month of soaking in water. Gingival fibroblasts were able to adhere and to get a specific orientation along the grooves and they show to be positively sensitive to the presence of keratin (improved proliferation). None of the tested surfaces increased bacterial adhesion compared to a mirror polished control. Conclusion: The findings of this study suggest nanogrooves and keratin nanofibers as promising modification strategies for the surface of transmucosal dental implants in the collar region in order to obtain an effective gum sealing and reduce bacterial penetration. Moreover, the proposed strategy supports byproduct recycling and is in line with a sustainable employment of resources.
Controlling soft tissue adhesion on titanium surfaces by nanogrooves and keratin nanofibres
Varesano A;Vineis C;Guarino V;Ambrosio L;
2017
Abstract
Introduction: Despite of wide research on surface modifications of the titanium implants for bone contact applications, a relatively low number of works consider interaction between the titanium surfaces and soft tissues. However, this topic is of interest in several cases, such as the transmucosal dental and percutaneous orthopedic implants. The rationale of this research follows the following fundamental principles of surface engineering. Topography and roughness play a crucial role both in bacterial and cell adhesion, moreover specific chemical and biological stimuli can be sent to the cells in order to modulate the biological response to the implants. A lower Ra limit of 0.2 µm has been defined in literature in order to avoid an increased bacterial contamination [1]. In the case of soft tissues, fibroblasts preferentially adhere on polished substrates and can be guided by surface grooves [2]. Keratin has a well-known action of chemical stimulus on fibroblasts. On this basis, the specific aim of this research work is to modify titanium surfaces by means of nanogrooves and keratin nanofibers, in order to drive gingival fibroblasts alignment and proliferation through topographical and chemical stimuli without increasing bacterial adhesion. Material and Methods: Oriented nanogrooves were obtained on c.p. titanium by a mechanical route (specific polishing protocol) or by means of Electron Beam Welding (EBW) paying attention to keep the final surface roughness lower than 0.2 µm. Keratin was extracted from wool and nanofibers were deposited onto mirror polished or roughened titanium substrates by electrospinning both as fibers randomly oriented or aligned to the grooves. The viability and orientation of human gingival fibroblasts were investigated on the modified surfaces together with bacterial (S. aureus) adhesion and biofilm formation.Results and Discussion: Oriented nanogrooves (Ra 0.1-0.2 µm) were successfully obtained on titanium substrates both by mechanical and EBW routes. Keratin nanofibers were deposited on the titanium surfaces without significantly altering surface roughness and they resulted stable up to 1 month of soaking in water. Gingival fibroblasts were able to adhere and to get a specific orientation along the grooves and they show to be positively sensitive to the presence of keratin (improved proliferation). None of the tested surfaces increased bacterial adhesion compared to a mirror polished control. Conclusion: The findings of this study suggest nanogrooves and keratin nanofibers as promising modification strategies for the surface of transmucosal dental implants in the collar region in order to obtain an effective gum sealing and reduce bacterial penetration. Moreover, the proposed strategy supports byproduct recycling and is in line with a sustainable employment of resources.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
