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Dimensional stability of a novel polyvinyl siloxane impression technique
Leão, Moira Pedroso; Pinto, Camila Paloma; Sponchiado, Ana Paula & Ornaghi, Bárbara Pick
Abstract
Aim: To introduce a modification of the reline impression technique (MRIT), and compare the
dimensional changes of impressions obtained by MRIT and by conventional reline impression
technique (CRIT). Methods: An acrylic resin tablet was milled by a CAD-CAM system to simulate
three abutments (A, B and C) with different distances among them. The abutments were molded
using both impression techniques. For MRIT, before completing the putty silicone polymerization,
the relieve procedure was made by compression and it was immediately repositioned to complete
the polymerization. Impressions were stored dry at room temperature for different periods
(immediately, 1 h, 2 days and 7 days). The distances were obtained by scanning. The differences
between the impressions and their respective matrix reference measurements were calculated to
determine the dimensional changes. Data were subjected to ANOVA and Tukey’s test (p<0.05).
Results: For AB and BC distances, there was no statistically significant difference between CRIT
and MRIT (p=0.0597 and p=0.2167, respectively). For AC, there was statistically significant
difference between the techniques for the immediate storage time (p=0.006). In general, for CRIT
the material showed expansion, while for MRIT it showed contraction. Conclusions: It was
verified that the addition silicon impressions obtained by both impression techniques showed
dimensional stability, except for the immediate time-point.
Keywords
dimensional measurement accuracy; dental impression materials; dental impression technique; laboratory research
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