Abstract: Objective To reveal the wettability of hydrophilic silicone impression materials bydetecting static contact angle, dynamic contact angles and contact angle hysteresis. Methods 4 kinds of hydrophilic impression materials, which were AFFINIS MonoBody, ZEROSIL mono, Oranwash VL and HC, were studied, among which Oranwash VL was condensation silicone, while the others were addition silicone. Static contact angle was detected by means of sessile drop goniometry in the moment the water drop was released to the surface of materials, as
well as 120 s later. Dynamic contact angles, including advancing contact angle and receding contact angle, were detected by means of tilting plate goniometry. And contact angle hysteresis was then calculated. Results Initial static contact angle of 4 silicone impression materials were all above 100°, while reducing to less than 90°120 s later except Oranwash VL. Static contact angles of 4 materials in ascending order were: AFFINIS MonoBody, HC, ZEROSIL mono and Oranwash VL. And the order of dynamic contact angles were basically the same to that of static contact angle, except that the difference between HC and ZEROSIL mono was not significant. However, there were no significant differences among contact angle hysteresis of the 3 kinds of addition silicone impression materials, while that of Oranwash VL was significantly higher than the others. Conclusion There were differences in wettability among the selected hydrophilic silicone impressionmaterials, especially when it came to addition
sili-cones and condensation silicones. And to evaluate wettability of impression materials properly, static contact angle, dynamic contact angle and contact angle hysteresis all should be considered, instead of detecting static contact angle only.

Key words: silicone, dental impression materials, wettability, contact angle, contact angle hysteresis