In Vitro Biofilm Formation on Titanium and Zirconia Implant Surfaces

• Autores: Stefan Roehling, Monika Astasov Frauenhoffer, Irmgard Hauser Gerspach, Olivier Braissant, Henriette Woelfler, Tuomas Waltimo, Heinz Kniha, Michael Gahlert
• Localización: Journal of periodontology, ISSN 0022-3492, Vol. 88, Nº. 3, 2017, págs. 298-307
• Idioma: inglés
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• Resumen

  • Background: It has been hypothesized that zirconia might have a reduced bacterial adhesion compared with titanium; however, results from experimental studies are rather controversial. The aim of the present study is to compare biofilm formation on zirconia and titanium implant surfaces using an in vitro three-species biofilm and human plaque samples.

    Methods: Experimental disks made of titanium (Ti) or zirconia (ZrO2) with a machined (M) or a sandblasted (SLA) and acid-etched (ZLA) surface topography were produced. An in vitro three-species biofilm or human plaque samples were applied for bacterial adhesion to each type of disk, which after 72 hours of incubation was assessed using an anaerobic flow chamber model.

    Results: Zirconia showed a statistically significant reduction in three-species biofilm thickness compared with titanium (ZrO2-M: 8.41 μm; ZrO2-ZLA: 17.47 μm; Ti-M: 13.12 μm; Ti-SLA: 21.97 μm); however, no differences were found regarding three-species-biofilm mass and metabolism. Human plaque analysis showed optical density values of 0.06 and 0.08 for ZrO2-M and ZrO2-ZLA, and values of 0.1 and 0.13 for Ti-M and Ti-SLA, respectively; indicating a statistically significant reduction in human biofilm mass on zirconia compared with titanium. Additionally, zirconia revealed a statistically significant reduction in human plaque thickness (ZrO2-M: 9.04 μm; ZrO2-ZLA: 13.83 μm; Ti-M: 13.42 μm; Ti-SLA: 21.3 μm) but a similar human plaque metabolism compared with titanium.

    Conclusion: Zirconia implant surfaces showed a statistically significant reduction in human plaque biofilm formation after 72 hours of incubation in an experimental anaerobic flow chamber model compared with titanium implant surfaces.

    Peri-implant infections are among the main reasons for early and late implant failures.1 With regard to infections of successfully osseointegrated and functionally loaded implants, a reversible inflammatory reaction in peri-implant soft tissues, termed peri-implant mucositis, has to be distinguished from inflammatory reactions that are associated with peri-implant pocket formation and bone loss, called peri-implantitis.2-4 With regard to the etiology of peri-implant infections, microbial colonization is very important.5-7 On teeth and implant surfaces, bacteria live in mixed and structured communities that are irreversibly attached to each other and to the surface of the substrate. These bacterial communities are known as biofilm and lead to plaque accumulation over time.8 Similar to the process that occurs on teeth, it has been shown that plaque on implant surfaces can induce peri-implant mucositis,9,10 and if not removed, formed plaque can induce peri-implantitis infections with extensive loss of peri-implant crestal bone.11-13 Additionally, it has been found that besides surface roughness and surface free energy,14,15 type of biomaterial can also influence biofilm formation and subsequent plaque accumulation on implant surfaces.16 In recent years, zirconium dioxide (zirconia) has become an alternative to titanium for the fabrication of dental implants due to its tooth-like color and, as microrough surface topography shows, at least similar osseointegrative capacity to moderately rough titanium implants.17-20 Additionally, two investigations21,22 have shown fewer inflammatory cells in the peri-implant soft tissue of zirconia in comparison to titanium or other metals. However, with regard to microbial colonization and biofilm formations on zirconia in comparison to titanium surfaces, in vivo as well as in vitro studies were performed, but the results reported so far were rather controversial concerning amount of adhered bacteria on titanium versus zirconia.23-31 Thus, it remains unclear if published results are dependent on the material properties of titanium and zirconia or on the applied study protocol. However, an experimentally verified reduced bacterial adhesion on implant surfaces might be clinically associated with a reduced risk or incidence for peri-implant infections.

    The aim of the present study was to investigate commercially available machined and microroughened titanium and zirconia implant surfaces with regard to bacterial adhesion and accumulation of a defined three-species biofilm and of a human plaque biofilm using an in vitro anaerobic flow chamber model.