This study evaluated the effect of green propolis extract on the adhesion and biofilm formation of Candida species in dentistry materials. Phytochemical analysis of green propolis extract was performed by high-performance liquid chromatography. Adhesion was quantified by counting the number of yeast cells adherent to dental material fragments in a Neubauer chamber. Biofilm formation was determined by counting colony-forming units recovered from dental material fragments. The intensity of biofilm adhesion was classified as negative, weak, moderate, strong, or very strong. Fifteen compounds, mainly flavonoids, were identified in green propolis extract. All strains adhered to and formed biofilms on the surfaces of the orthodontic materials studied. On steel and resin, yeast cell adhesion intensities were weak at all incubation times, except for those of Candida parapsilosis and C. tropicalis, which were moderate at 12 h. At 24 and 48 h, C. albicans formed biofilms on steel with moderate adhesion affinities; at 24 and 48 h, C. parapsilosis formed biofilms with very strong affinities. C. tropicalis formed biofilms with strong and very strong affinities at 24 and 48 h, respectively. On resin, all species displayed strong affinity for biofilm formation at 24 and 48 h, except for C. tropicalis, which displayed very strong affinity at only 48 h. Green propolis extract displayed antifungal activity and inhibited both adhesion and biofilm formation at 2.5 μg/mL. This study reinforces the idea that green propolis has antifungal activity and interferes with the virulence of Candida species.

31Background: This study evaluated the influence of green propolis' extract on the 32 adhesion and biofilm formation of Candida species on dentistry material. Methods: 33 Phytochemical analysis of green propolis' extract was performed by High Performance 34 Liquid Chromatography. Adhesion was quantified in a Neubauer chamber, counting the 35 number of yeast cells adhered to the fragments; Biofilm formation was determined by 36 counting the number of colony forming units (CFU). The intensity of biofilm formation 37 adhesion was classified as negative, weak, moderate, strong and very strong. Fifteen 38 compounds were identified in green propolis extract, mainly flavonoids. Results: All 39 strains were able to adhere and form biofilm on the surface of the orthodontic materials 40 studied. In steel and resin, the adhesion intensity of the yeast cells was weak at all 41 incubation times, except for C. parapsilosis and C. tropicalis which at 12hs showed 42 moderate intensity. Regarding biofilm formation (24 and 48 hours), it was observed in 43 the steel that C. albicans had moderate intensity at 24 and 48 hours; C. parapsilosis at 44 24 and 48 hours had very strong intensity; C. tropicalis at 24 hours had strong intensity 45 and at 48 hours very strong. While in the resin, all species at 24 and 48 hours had strong 46 intensity, except for C. tropicalis which at 48 hours had very strong intensity. Green 47 propolis extract showed antifungal activity and was able to inhibit both adhesion and 48 biofilm formation at 2.5 µg/mL. Conclusions: This study reinforces the idea that green 49 propolis has antifungal activity and interferes with virulence factors of Candida species. 50 Keywords: Green Propolis; Candida sp, Biofilm; Dentistry material. 51 52 53 54 55 56 57 58 3 59 BACKGROUND 60In recent years the use of orthodontic materials has increased for aesthetic, surgical 61 and biofunctional purposes. Polymers, ceramics, composites, resin, steels and their 62 alloys are used in the manufacture of dental prostheses, screws and orthodontic 63 appliances and when implanted in the oral cavity they are exposed to colonization and 64 biofilm formation by microorganisms that live in the oral cavity. Alongside with the pH 65 and saliva, these devices are targets of biofilm formation especially produced by 66 Candida spp. (1). 67 A combination of factors contribute to Candida sp biofilm formation, salivary 68 flow, low pH, poor oral hygiene and the type of orthodontic material contribute to 69 biofilm colonization and formation (2). During colonization and biofilm formation, oral 70 microbiota secrete enzymes and exopolysaccharides to colonize a surface, thus the 71 biofilm constitutes as a film of organic components that are absorbed from saliva 72 forming an extracellular polymeric matrix and thus the multicellular community 73 (bacteria or fungus) is incorporated into the extracellular matrix (ECM) (1-3). 74The formation of biofilm in orthodontic materials raises concern as, when 75 installed, increases the risk of infection...