Objective: This study evaluated the effect of viscosity of vinylpolysiloxane impression materials(VIM) with different surfactant concentrations on: 1) impression material contact angles(ICA) on moist dentin; 2) water contact angle(WCA) on the cured VIMs. Method: Four groups of VIMs containing 0-5%wt of Igepal CO520 surfactant (Rhone-Poulenc) were prepared with variances in viscosity for each group. Contact angles of VIM or distilled water droplets(2ul) were measured at 60s on both sides of the droplets(n=3) using an automated video contact angle goniometer (100-00-115-S, Rame-Hart). Viscosity at stress of 1Pa was measured using a rheometer (SR2000, Rheometrics) with two parallel plates(F25mm, 0.5mm gap) oscillating at 1Hz at 25°C(n=3). Results: VIMs without a surfactant had much lower viscosity than VIMs with a surfactant. VIMs with no surfactant gave the lowest ICA and the largest WCA. VIMs with 1% surfactant had larger ICAs due to an increase in viscosity. WCA significantly decreased even in the presence of 1% surfactant. Further increase in surfactant concentration resulted in only small changes in ICA and WCA. ANOVA analysis revealed that different viscosity VIMs at the same surfactant concentration had different ICA and WCA. The higher the viscosity of VIMs, the larger the ICA and the lower the WCA.
|
0% Surfactant |
1% Surfactant |
|||||
|
Viscosity(Pa.s) |
10±0a |
14±0b |
26±2c |
39±6A |
92±1B |
341±33C |
|
ICA(degree) |
25±2a |
30±2b |
43±0c |
46±2A |
55±2B |
59±1B |
|
WCA(degree) |
106±3a |
104±1a |
97±2b |
54±0A |
49±1B |
47±2B |
|
3% Surfactant |
5% Surfactant |
|||||
|
Viscosity(Pa.s) |
57±1a |
116±13b |
349±29c |
84±1A |
170±15B |
463±33C |
|
ICA(degree) |
54±1a |
59±1a |
66±4b |
53±1A |
55±3A |
67±2B |
|
WCA(degree) |
36±0a |
33±2a, b |
31±2b |
34±2A |
32±1B |
38±0C |
*Means with the same letters within the same row are not significantly different (p<0.05).
Conclusions: The viscosity of vinylpolysiloxane impression materials significantly affects the impression material contact angles on dentin. The surfactant has a greater effect on the water contact angles than on the impression material contact angles.