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 6h; then, at 2-h intervals for the next 14h; then, at 24 and 30h. 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±1058min) (P<0.05). Group 3 had the lowest flowability (30.0±0.7mm) and the highest radiopacity (14.85±1.8mm 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.