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Interval of sucrose exposure, biofilm composition and enamel demineralization

Livia Helena Terra e Souza
Total Authors: 1
Document type: Master's Dissertation
Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Odontologia de Piracicaba
Defense date:
Examining board members:
Lívia Maria Andaló Tenuta; Cecilia Pedroso Turssi; Carolina Patrícia Aires
Advisor: Jaime Aparecido Cury

Sucrose is considered the most carcinogenic carbohydrate of the diet and the effect of the interval of the exposure frequencies must be considered, however there is a lack of experimental studies in humans in order to prove its importance, which is the main objective of this study. Therefore, an in situ study was performed, blind in relation to the examiner, and crossover in four phases. The studied factor was the interval between the exposures to 20% sucrose used at a frequency of 8x/day. The experimental groups included no solution of exposure (control), and intervals of 15, 45, 90 minutes among the exposures to sucrose. Fifteen adult volunteers used an acrylic palatal appliance containing four blocks of human enamel, with pre-established surface hardness. The sucrose treatments were made extra-orally. The volunteers used non fluoride toothpaste a week before and during the experimental phases. In the morning of the 15th day of each phase, the biofilm formed on the blocks was collected and weighed. The biofilms formed over 2 blocks, anterior left and posterior right of the appliance were collected for microbiological and polysaccharide analyses. The biofilm from the other two blocks was collected for the inorganic analysis of the concentrations of Ca, Pi and F in the fluid and the solid parts of the biofilm. The determination of Ca and Pi in the fluid and solids of the biofilm was conducted using colorimetric reagents. For the determination of F in the fluid and solids of the biofilm, an inverted F electrode, adapted for microanalysis, was used. Total microorganisms, mutans streptococci, Actinomyces viscosus and lactobacillus were analyzed. The colony forming units (UFCs) were counted and the results expressed as UFC/ mg of wet weight of the dental biofilm. The polysaccharides extracted were determined by a colorimetric method. After biofilm extraction, the enamel blocks were removed from the appliances and their demineralization was determined by means of the surface and cross-sectional hardness. Analisys of variance was used for the effect of the treatments, and the Tukey test was used, when the effect was significant, for comparing the groups. The results showed that there was greater loss of hardness in the 45 and 90 minute intervals. However, there was no difference in the concentrations of F, Ca and Pi in the solid part of the biofilm, but in the fluid, a higher concentration of Ca was found in the 90 minute interval. There was a gradual increase in the concentration of intra and extracellular polysaccharides the longer the interval. As for the microorganism counting, relating to lactobacillus, difference was found between the control group and the interval groups tested, but these did not differ among each other. There was no difference between groups referring to mutans streptococci and Actinomyces viscosus. It is concluded that the interval of time between the same daily frequencies of exposure to sucrose must be considered in dietetic orientations, since longer intervals change the composition of the dental biofilm formed, causing higher enamel demineralization. (AU)

FAPESP's process: 09/12092-1 - Effect of intervals of sucrose exposure on enamel desmineralization and dental biofilm composition
Grantee:Lívia Helena Terra e Souza
Support type: Scholarships in Brazil - Master