Methods: RC (Racestyptine, Septodont, France) were placed centrally in a resin tube of 15mm length and straightened using a weight of 10g. Each RC was saturated with 8µl of test solution and the tube was filled with impression material. The RC was pulled out using a universal testing machine (Z010/02, Zwick, FRG) at a crosshead-speed of 5mm/min. The force at which the RC lost adhesion in the impression material was measured to evaluate the effect of the astringents. A polyvinylsiloxane (PVS) (Aquasil, Dentsply-Caulk, USA), and two polyether: PEA (Permadyne, 3M-Espe, FRG) and PEB (P2, Heraeus-Kulzer, FRG) were tested with four astringents: adrenaline (AD) (Surgident, Sigma, FRG), iron-sulfate (IS) (Astringedent, Ultradent, USA), aluminum-sulfate (AS) (Orbat-sensitive, lege-artis, FRG) and aluminum-chloride (AD) (Racestyptine, Septodont, France). Dry RC (DRC) and RC saturated with distilled water (WRC) served as controls (n=8). Mean value of WRC was set 100% to evaluate the astringents. Statistical analysis was performed using ANOVA with post-hoc Scheffé-procedure (p≤0.05).
Results: Mean force for WRC was 16.5±0.8N for PVS (DRC 28.7±2.8N), 22.4±0.7N for PEA (DRC 32.4±1.5N) and 4.1±0.4N for PEB (DRC 20.7±1.1N). For PVS all astringents resulted in higher values, significant for IS and AS (125% resp. 122%). For PEB the use of IS, AS and AC resulted in significantly higher values (219-323%) whereas AD had no significant effect. For PEA the use of all astringents resulted in significantly lower values with 64% for AD and 13-15% for IS, AS and AC.
Conclusion: Polymerization of polyether PEA was inhibited by all astringents. Polyvinylsiloxane PVS and polyether PEB were not negatively affected; adhesion to the RC compared to distilled water was partially improved especially for PEB.