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| Author(s): |
Livia Maria Andalo Tenuta
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Bauru. |
| Institution: | Universidade de São Paulo (USP). Faculdade de Odontologia de Bauru (FOB/SDB) |
| Defense date: | 2001-06-06 |
| Examining board members: |
Jose Eduardo de Oliveira Lima;
Maria Francisca Thereza Borro Bijella;
Jaime Aparecido Cury
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| Advisor: | Jose Eduardo de Oliveira Lima |
| Abstract | |
The aim of this study was to evaluate the in situ enamel demineralization during 4, 7 and 10 days and some of the factors influencing the process. Before the beginning of the in situ phase, a stimulated whole saliva sample was collected from 13 volunteers for 5 min and the salivary secretion rate, buffering capacity and numbers of mutans streptococci were estimated. A palatal appliance containing 4 polished bovine enamel blocks (4 X 4 X 2 mm) covered by a plastic mesh was worn on 3 separate periods of 4, 7 and 10 days, throughout which time a non-fluoridated dentifrice was used. A 20% sucrose solution was dripped extra-orally onto the enamel blocks 10 times a day. All enamel blocks were evaluated by the analysis of enamel surface microhardness before and after in situ demineralization, using a 50 g, Knoop load for 5 s. At the end of each period, plaque covering the enamel blocks was collected and analyzed for the % of mutans streptococci of the total viable counts. Paired-t test showed that initial and final microhardness were statistically different at the three periods evaluated (p<0.05). Change in surface microhardness (%CSMH) was 13.8%, 19.3% and 48.3% during the 4, 7 and 10-day periods, respectively. There was no statistically significant difference on the %CSMH between 4 and 7 days, according to analysis of variance and Tukeys test (p<0.05). Correlation between %CSMH and the salivary and bacteriological factors evaluated was determined using Pearsons and Spearmans coefficient of correlation (p<0.05). The %CSMH was not significantly correlated to the salivary factors determined initially. In about half of the plaque samples analyzed mutans streptococci were not detected, although the enamel showed some demineralization. The % of mutans streptococci in plaque samples was not correlated to its numbers in saliva. There was no statistically significant correlation between the %CSMH and the % of mutans streptococci in plaque over the enamel blocks. The presence of these bacteria in plaque significantly increased enamel demineralization when compared to the blocks where they were not detected only at 4 days, according to Mann-Whitney test (p<0.05). The results showed in situ enamel demineralization after short periods of plaque accumulation, which was not related to the salivary factors evaluated nor to the numbers of mutans streptococci in saliva or plaque. (AU) | |