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| Author(s): |
Rosa Virginia Dutra de Oliveira
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Araraquara. 2016-04-18. |
| Institution: | Universidade Estadual Paulista (Unesp). Faculdade de Odontologia. Araraquara |
| Defense date: | 2016-03-21 |
| Advisor: | Fernanda Lourenção Brighenti |
| Abstract | |
The proximity between microorganisms present in dental biofilm determines the existence of interaction between them, which can benefit or antagonize the involved species. The aims of this study were: 1) to present a review about interactions among cariogenic bacterial species within oral biofilm; 2) to show the applicability of the drip flow reactor (DFR) for developing oral biofilms and testing antimicrobial agents; 3) to evaluate the growth and chlorhexidine susceptibility of biofilms comprised by Streptococcus mutans ATCC 25175 and Lactobacillus acidophilus ATCC 4356, using DFR; 3) to assess the growth and chlorhexidine susceptibility of biofilms comprised by Streptococcus mutans ATCC 25175 and Actinomyces naeslundii ATCC 12104, using DFR. Biofilms grew on hydroxyapatite coated glass slides, with BHI broth at 10 mL/h flow rate supplemented with 0.2 or 0.5% sucrose depending on the species used. DFR was incubated for 24 h at 37 °C / 5% CO2. Biofilms were treated with 0.2% chlorhexidine (CHX) or 0.9% NaCl for 2 min. Growth and effect of treatments were determined by colony forming units (CFU) counts. Biofilms were stained using the Live/Dead Viability kit and analyzed by confocal laser scanning microscopy (CLSM) to differentiate bacterial cells without damage and damaged by the action of CHX. DFR validation was analyzed by unpaired t test (α=0.05). Interaction evaluation was analyzed by two-way ANOVA and Tukey test (α=0.05). Literature review showed the role of microbial interactions in balancing competition/coexistence. For DFR validation, results showed that despite distinct initial concentrations of S. mutans mono-cultures, chlorhexidine treatment affected both biofilms at the same proportion. No interaction between treatment solution and culture condition was found in S. mutans and L. acidophilus biofilms. However, viability was significantly reduced by CHX treatment. L. acidophilus in mono-culture grew significantly less than S. mutans in either mono or mixed-culture. S. mutans and A. naeslundii grew similarly in both culture conditions within NaCl group. Bacterial viability was significantly reduced in all groups treated with chlorhexidine, except for S. mutans in mixed-cultures. A. naeslundii in mono-culture was the most susceptible group, whereas S. mutans in mixed-cultures was the least susceptible. In conclusion, relationships among microorganisms may influence the occurrence of dental caries. The present study showed the applicability of the DFR for growing oral biofilms and testing antimicrobial agents. Significant interactions were found between S. mutans and A. naeslundii but not between S. mutans and L. acidophilus. (AU) | |
| FAPESP's process: | 12/17236-4 - Microbial interactions between cariogenic bacteria: evaluation of growth, metabolic activity, biochemical composition and susceptibility to chlorhexidine of biofilms formed in vitro |
| Grantee: | Rosa Virginia Dutra de Oliveira |
| Support Opportunities: | Scholarships in Brazil - Doctorate |