Effect of incorporation of cellulose nanocrystals in a denture base resin on superficial properties and simple and mixed Candida albicans and Methicillin-sensitive Staphylococcus aureus (MSSA) biofilms

Author(s)

Thaís de Sousa Santana

• Document type: Master's Dissertation
• Press: Araraquara. 2021-06-09.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Odontologia. Araraquara
• Defense date: 2021-05-27
• Advisor: Ana Carolina Pero

Abstract

The use of biopolymers from renewable sources as nanometric reinforcing agents can represent an important innovation in dental materials. The aim of this study was evaluate the simple and mixed biofilm formation of Candida albicans and methicillin-susceptible Staphylococcus aureus (MSSA) and microorganisms’ viability on the surface of acrylic resin for denture base, after the incorporation of cellulose nanocrystals (CN). Cellulose nanocrystals (NC) isolated from wood pulp (Eucalyptus Urograndis) were incorporated into acrylic resin for denture base (Onda-Cryl® - OC, activated by microwave energy). Disc-shaped specimens (15 x 3 mm) were obtained (N=240) for each condition (groups 0%CN - control, and 0.75%CN) Prior to the adhesion and biofilm formation tests, the surface roughness was measured (n=120) in a digital rugosimeter (Ra, µm) and the surface free energy (SFE) was measured from contact angle measurements (n=120), obtained by means of a goniometer connected to a computerized system. The formation of biofilms was performed from the inoculation of C. albicans and S. aureus on the acrylic resin discs, which were incubated at 37ºC for 90 minutes and 48h. After both periods, the analysis of cell metabolism test (XTT) was performed (n=9); evaluation of antimicrobial activity by counting colony-forming units (CFU/ml) (n=9) and analysis by confocal laser microscopy (n=2). All analyses were performed in triplicate on 3 distinct occasions. Data were tabulated and submitted to Student t test and non-parametric Mann-Withney U test, according to adherence to normality, at 5% of significance level. The incorporation of NCs (0.75%) did not influence the results of the surface roughness and surface free energy (SFE) tests for OC acrylic resin (P>0.05). It was also observed, (XTT method and CFU/mL log), that there was no significant difference between the groups for the adhesion and formation of biofilm of the different microorganisms analyzed. The confocal laser microscopy exhibited images that show the viability of the microorganisms and these were similar for both groups (control and NC 0.75%). Thus, it could be concluded that the incorporation of 0.75% of NC did not influence the physical (roughness and free surface energy) and microbiological (adhesion and biofilm formation/confocal microscopy) properties of the acrylic resin for denture base. (AU)

• FAPESP's process: 19/07491-6 - Effect of incorporation of cellulose nanocrystals on adhesion and biofilm formation of simple and mixed Candida albicans and methicillin-sensitive Staphylococcus aureus (MSSA) in a denture base resin
• Grantee: Thais de Sousa Santana
• Support Opportunities: Scholarships in Brazil - Master