Objectives:
The clinical success of a precision impression material depends both on good
mechanical properties of the elastomer during removal of the set impression
from the mouth and on good wetting behaviour in moist environment and while
pouring the impression. The hydrophilicity of VPS impression materials can be
increased by addition of surfactants, which are assumed to not take part in the
elastomer network formation. The aim of this study was to investigate the
influence of the degree of hydrophilization on the elastomeric properties of
VPS impression materials. Methods: Tensile strengths and hydrophilization
of the following materials were compared: Provil Novo Light (Heraeus Kulzer, PN),
Express Light (3M ESPE, EL), Panasil Contact Plus (Kettenbach, PC)
and the newly developed Express Ultra Light Body (3M ESPE, EU). To
determine the degree of hydrophilization two specimens (38mmx32mmx3mm) of each
material were produced. One hour after mixing base and catalyst paste the 10
second contact angle (CA) of three drops of water on each specimen was
determined using a standard goniometer. Tensile strength was determined by
producing six I-shaped specimens with a central unit of 20mmX4mmx2mm. Ten hours
after mixing of base and catalyst paste tensile strength was measured using a Zwick
machine. Results: Mean values and standard deviations are given. ANOVA
(p<0,05) and Tukey tests confirmed significant differences for CA and
tensile strength data except groups indicated by asterisks.
|
Material
|
EL
|
PN
|
PC
|
EU
|
|
CA
|
65 (1)
|
78 (2)
|
105 (1)
|
42 (4)
|
|
Tensile Strength
|
2,4 MPa (0,1)*
|
2,6 MPa (0,1)*
|
3,1 MPa (0,2)
|
4,4 MPa (0,4)
|
Conclusion:
EL, PN and PC show a tendency towards decreasing tensile strength with
increasing degree of hydrophilicity indicated by decreasing CA. In contrast the
newly developed EU shows highest tensile strength and hydrophilicity in this
test