Sample studies on the hygenic properties of zirconia
Studies have demonstrated that zirconia has a lower bacterial count
and inflammatory infiltrate compared with titanium. Because of
zirconia’s hygienic properties it has natural benefits in
maintaining esthetic soft tissue and preserving crestal bone.
Rimondini et al. performed in vitro and in vivo tests comparing
bacteria accumulation on zirconia and titanium. They concluded that
fewer bacteria than titanium.
Rimondini et al.’s study on the hygienic properties of zirconia
compared with titaniumIn vitro test
• Disks of titanium and zirconia were used and tested for bacteria
• Cultures were incubated for 4 days and the bacterial counts were
• Zirconia showed significantly less bacterial growth in vivo test
• Zirconia and titanium were placed onto silicone stents and
attached to orthodontic wires intraorally
• The stents were worn for 24 hours and removed
• Bacterial counts were measured on the zirconia and titanium
• Zirconia was found to have a lower bacterial count than the
Scarano et al.’s 2004 work also aimed at comparing the hygienic
properties of titanium and zirconia.
Their results were similar to Rimondini’s results – that zirconia
is a more hygienic material.
Poortinga et al.’s 1999 research demonstrated that zirconia’s
resistance to bacterial adhesion is likely due to the electron
conductivity of this material. They demonstrated that the charge
transfer occurs during bacterial adhesion. Bacteria that donate
electrons adhere to the substrate more strongly than bacteria that
Inflammatory response with zirconia use
A natural response to the presence of bacteria is the release of
inflammatory mediators which leads to boneloss. Rather than
evaluating the biofilm, another
method of evaluating hygienic properties is to evaluate
inflammatory factors such as vascular endothial growth factor
(VEGF), nitric oxide synthase expression,
inflammatory infiltrate, and microvessel density in theperi-implant
soft tissues. An increased level of these factors indicates the
presence of inflammation due to
In 2006, Degidi et al. used these inflammatory markers to evaluate
the hygienic properties of zirconia compared with titanium.
Degidi et al.’s study on inflammatory infiltrate levels with
zirconia and titanium
• Implants were placed into human patients
• Half of the abutments were made of zirconia, while the other half
were titanium abutments
• After 6 months biopsies were taken and analyzed for inflammatory
• Significantly less inflammatory infiltrate was noted around the
zirconia abutments compared with the titanium abutments
As a side note, regardless of the material used, if there is a
micro-gap between the implant and abutment, inflammation and
crestal bone loss may occur.
As a result, platform switching has been proposed as a solution to
reduce the gap and limit crestal bone loss.