universidade de são paulo - Faculdade de Odontologia - Unesp

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XTT assay
Nine specimens from each group were evaluated by XTT reduction assay,
as described elsewhere 1 . Briefly, XTT (Sigma, MO, USA) was prepared in
ultrapure water (1mg/ml), filter sterilized and stored at -70 ºC until used.
Menadione (Sigma, MO, USA) solution was prepared in acetone at 0.4 mM
immediately before each assay. After washing, the specimens were transferred to
new wells with 158 μl PBS with 200mM glucose, 40 μl XTT and 2 μl menadione
were inoculated to each well. The plates were incubated for 3 h in the dark at 37
ºC. The whole content of each well was centrifuged at 5000 g for 2 minutes and
the colorimetric change of the supernatant was measured using a microtiter plate
reader (Thermo Plate – TP Reader) at 492 nm.
Statistical Analysis
Comparison of the roughness values among the groups was performed by
the non-parametric Kruskal-Wallis test. For each adhesion assay used, one-way
analysis of variance with Welch's correction was performed to evaluate the effect
of time of preconditioning with saliva on Candida albicans adhesion. For the
crystal violet technique, data of yeast counts (cells per mm 2 ) were transformed by
log. A significance level of 0.05 was used for all statistical tests. To evaluate the
correlation between the two methods used for assessing C. albicans adherence,
Pearson’s coefficient of correlation was used.
Results and Discussion