universidade de são paulo - Faculdade de Odontologia - Unesp

64
After roughness measurements, the specimens were cleaned in an
ultrasonic cleaner using water and detergent bath for 15 minutes, then sonicated in
distilled water for 15 minutes and air dried. The specimens were then divided into
five groups, each including 18 specimens processed against stone and 18
polymerized in contact with glass. In the control group, the specimens were left
untreated. For the four experimental groups, both specimen surfaces were exposed
to plasmas generated under the following conditions: argon atmosphere at 50 W
(group Ar/50 W); argon/oxygen atmosphere at 70 W (group ArO 2 /70 W);
atmospheric air at 130 W (AAt/130 W); argon atmosphere, followed by plasma
treatment in a sulfur hexafluoride atmosphere, both performed at 70 W (group
Ar/SF 6 70 W). The plasma exposure time (5 minutes) and the position of the
specimens within the plasma chamber were kept unchanged. To determine the
plasma parameters used in the experimental groups, pilot experiments were
performed, in which various conditions of exposure time, atmosphere composition
and pressure, and radiofrequency power were tested. For groups Ar/50 W,
Ar/O 2 70 W and AAt/130 W, the plasma parameters were chosen based on the
degree of surface hydrophobicity. Parameters that produced surfaces with low
hydrophobicity (contact angle close to zero) were used for group AAt/130 W. For
groups Ar/50 W and Ar/O 2 70 W, parameters that provided hydrophobicity values
between those of the untreated specimens (higher hydrophobic) and those of the
group AAt/130 W specimens were chosen. In the case of group Ar/SF 6 70 W, the
pilot experiments established the appropriate conditions for the incorporation of
fluorine into the surfaces. Fluorine incorporation was confirmed by photoelectron