Biomedical Engineering Reference
In-Depth Information
isolates from previously worn dentures in the Northeast and Southwest regions of the
United States (Glass, 2010); in their conclusions, the authors pointed out frequent denture
use without appropriate disinfection and biofilm formation within the pores of the material.
In a previous study (Vanden Abbeele et al., 2008), authors reported
Candida
contamination of
upper prosthesis in 76% of denture wearers hospitalized for long-term care in geriatric units.
The most frequently isolated species were
C. albicans
(78%),
C. glabrata
(44%) and
C. tropicalis
(19%). Carriage of more than one yeast species was found in 49% of the contaminated
dentures. There was a significant association between denture contamination and palatal
mucosa colonization, making
ex vivo
denture decontamination mandatory,
together
with
in
vivo
mucosa disinfection.
Candida
carriage has been observed in different types of dentures,
both with and without soft liner fittings (Bulad et al., 2004; Mutluay et al., 2010).
Adhesion of
Candida
to the base materials of the dentures is associated with denture plaque
(i.e. denture biofilm) and denture-related stomatitis. Even if many observations support the
presence of
Candida albicans
in the biofilms on dentures, insufficient data are available to
assess the etiology and to understand the pathogenesis of
Candida
-associated denture
stomatitis. Review of the literature (Radford et al., 1999; Pereira-Cenci et al., 2008) does not
permit settling specific and non-specific plaque hypotheses. Indeed, denture plaque
comprises an ill-defined mixture of bacteria (such as
Streptococcus spp
.,
Lactobacillus spp
.,
Staphylococcus aureus
, and Gram-negative anaerobic bacteria) with
Candida spp
. also apt to
cause mucosa inflammation.
2.2
Candida
on other materials inserted in the oral cavity
Candida spp
. was detected in low proportions at peri-implantitis sites and in failing implants
associated with periodontopathogenic bacteria such as
Porphyromonas spp
.,
Prevotella spp
.
and
Actinobacillus actinomycetemcomitans
(Alcoforado et al., 1991; Leonhardt et al., 1999; Pye
et al., 2009), but ecological relationships with their surrounding and eventual pathological
roles are yet to be understood.
In vitro
,
Candida albicans
may also adhere to pieces of
biodegradable membranes used for periodontal tissue regeneration (Molgatini et al., 1998)
and to tissue-conditioning materials for denture relining (Kulak & Kazazoglu, 1998).
Additionally, presence of
Candida albicans
has been documented on obturator prostheses
(whatever the material may be: silicone, polymethyl methacrylate, or titanium) in patients
with maxillary defects (suffering from congenital malformation, tumors, or trauma), and on
the mucosa adjacent to the prosthesis (Depprich et al., 2008; Mattos et al., 2009); these
patients can present prosthesis-induced stomatitis. Finally, the use of orthodontic appliances
leads to an increased carriage rate during the appliance-wearing time, with a significant fall
of salivary pH and an increase of
Candida
count observed at different oral sites through
various sampling techniques (Hibino et al., 2009).
2.3
Candida
on devices used outside the oral cavity
Materials inserted in other sites can be colonized by yeasts as well, causing device-related
infections (Cauda, 2009): articular prosthesis, cardiac devices (Falcone et al., 2009), catheters,
vascular access devices (Brouns et al., 2006), and voice prostheses (Kania et al., 2010). These
infections require prolonged antifungal therapy and often device removal.
3. Experimental approach
A better understanding of interface biology and material surface treatments requires
experimental models to produce
in vitro
biofilms on supports that are easy to manipulate in