**7. Acknowledgment**

The author reports no conflicts of interest in this work. The author wishes to thank the students from the *Haute Ecole Francisco Ferrer* (Medical Biology section) and the *Université Libre de Bruxelles* (Faculty of Medicine, Dentistry section) in Brussels who enthusiastically participated in studies on biofilm biology in the frame of their final memory or doctorate. The author also thanks Pr M. Stas, MD PhD for her helpful advice and review of the manuscript.

#### **8. References**

484 Biomaterials – Physics and Chemistry

culture reflect the biomass present on the oral surfaces, but this is not the number of yeast cells included in oral biofilms. Colony forming units (CFU) counted on the agar medium represented only a small part of the cells harvested by the cotton, as assessed by three successive spreadings of the same cotton that provided similar data (in the range interval of 0.1 logarithmic units). Furthermore, two successive swabs of the same oral surface yielded

Finally, investigators themselves can influence the hygiene behavior of the subjects under study. The study previously quoted (Vanden Abbeele et al., 2008) also analyzes the effect of the oral care program. In the absence of any hygiene advice, a second denture swabbing taken in 46 patients after an interval of one week demonstrated only minor variations, thus minimizing the hygiene-stimulation effect produced by pursuing the collection of samples. Repeated sampling (at one-week intervals) of 46 different healthy denture-wearers demonstrated yeast counts remaining in the same range (±1 logarithmic unit) for more than 85% of the denture swabs and mucosa samples. Values below the lower limit (-1 logarithmic unit) occurred in less than 15% of denture and mucosa swabs. This was attributed to behavioral changes in hygiene practice following the investigators' first visit. By contrast, a hygiene program including a placebo oral gel (tested to be inactive *in vitro*) led to a decrease

Yeasts belonging to the *Candida* genus usually colonize the human oral cavity. *In vivo* and *in vitro* studies have shown *Candida* incorporation into biofilms covering different biomaterials and devices such as dentures. These biofilms may indicate an increased risk factor for invasive candidosis when the host immune system is compromised. Daily denture brushing is recommended to all denture (and other device) wearers in order to prevent the development of *Candida* biofilm. Family members and healthcare workers must assume this task when there is a deficiency in dexterity and/or a loss of autonomy, especially in elderly and disabled persons. In case of candidosis in denture-wearers, decontamination of dentures is mandatory. Antimycotics such as azoles or nystatin must be reserved for curative treatment of infected patients; they are less active against *Candida* biofilms on dentures and could lead to emergent resistance if applied daily to dentures in order to prevent yeast colonization. Nevertheless, few studies, if any, integrate all aspects of denture care: welfare of denture-wearers, prevention of candidosis, biomaterial defects after decontamination processing, and possible *Candida* biofilm development. Daily brushing of dentures remains the key recommendation. A better understanding of *Candida* biology in the oral environment will provide new tools to control *Candida* biofilms, the possible development of more appropriate biomaterials for dentistry (or surface improvements), and better management of biomaterial use in the oral cavity. Further investigations in this field

The author reports no conflicts of interest in this work. The author wishes to thank the students from the *Haute Ecole Francisco Ferrer* (Medical Biology section) and the *Université Libre de Bruxelles* (Faculty of Medicine, Dentistry section) in Brussels who enthusiastically participated in studies on biofilm biology in the frame of their final memory or doctorate.

will require cooperation among dentists, biologists, and engineers.

similar quantities of yeast cells (in the range interval of 0.5 logarithmic units).

of yeast carriage after two weeks.

**6. Conclusion** 

**7. Acknowledgment** 


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