universidade de são paulo - Faculdade de Odontologia - Unesp

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The surface roughness of all specimens was measured with a profilometer
(Mitutoyo SJ 400 – Mitutoyo Corporation – Tokyo, Japan). Four measurements
were made for each specimen and the average reading was designated as the Ra
(μm) value of that specimen. Resolution was 0.01 μm, interval (cutoff length) was
0.8 mm, transverse length was 2.4 mm, the stylus speed was 0.5 mm/s, and the
diamond stylus tip radius was 5 μm. All measurements were recorded by one
operator. Only samples with an average surface roughness ≤ 0.2 μm were selected
for this study.
Specimen sterilization and group assignment
Before the microbiological tests, the specimens were kept in distilled water
at ambient temperature for 48 hours, in order to eliminate residual monomers [30].
After this, they received an ultrasound bath for 20 minutes and were exposed to
ultraviolet light in the laminar flow chamber for 20 minutes on each side [39].
Hence, the 72 specimens were divided into four groups (n=18), as follows:
1 control (C), without preconditioning in saliva, and 3 experimental groups (G 1 ,
G 2 and G 3 ) that were conditioned with saliva prepared as described below.
Saliva collection and preparation
For the experimental groups G 1 and G 2 , whole human unstimulated saliva
from 15 healthy adult volunteers was expectorated into sterile 50 ml Falcon tubes
on ice, pooled and clarified by centrifugation. Thereafter, for group G 1 , the saliva
was centrifuged at 10000 rpm for 5 min at 4 ºC [30], while for group G 2 , saliva
was centrifuged at 12000 rpm for 30 min at 4 ºC [18-19, 22, 25, 27-28].