Variability of physicochemical properties of an epoxy resin sealer taken from different parts of the same tube.

AIM: To analyse several physicochemical properties of AH Plus (Dentsply DeTrey, Konstanz, Germany), including setting time, flow, radiopacity and the degree of conversion (DC); and to correlate the results with the source of the material: from the beginning, middle or end of the tubes in which they were supplied. METHODOLOGY: Three experimental groups were established for each property investigated. Group 1 corresponded to material taken from the beginning of tubes A and B; Group 2 corresponded to material taken from the middle of each tube; and group 3 corresponded to that from the end of each tube. The setting time, flow and radiopacity were studied according to American National Standards Institute/American Dental Association (ANSI/ADA) Specification 57. DC was determined from infrared spectra, which were recorded at 1-h intervals for the first 6 h; then, at 2-h intervals for the next 14 h; then, at 24 and 30 h. Data were analysed statistically by analysis of variance (anova), Tukey-Kramer, Kruskal-Wallis and Dunn tests, with a significance level of 5%. RESULTS: Group 1 had a significantly longer setting time (2303 ± 1058 min) (P < 0.05). Group 3 had the lowest flowability (30.0 ± 0.7 mm) and the highest radiopacity (14.85 ± 1.8 mm Al) (P < 0.05). No differences were found for the DC test (P > 0.05). CONCLUSION: The results suggest that segregation occurs between the organic and inorganic components of AH Plus sealer, thereby changing the setting time, flow and radiopacity.