Tooth discoloration induced by endodontic materials: a laboratory study.

To investigate the discoloration potential of endodontic materials using a bovine tooth model. Two hundred and 10 dentine-enamel cuboid blocks (10 × 10 × 3.5 mm) were prepared out of the middle thirds of bovine tooth crowns. Standardized cavities were prepared in the walls of the pulp chamber leaving 2 mm of enamel and dentine on the labial wall of the crown. The specimens were randomly assigned to 14 groups (n = 15). Endodontic materials were placed into the cavities as follows: group A: empty, group B: blood, group C: calcium hydroxide, group D: ApexCal, group E: Ultracal XS, group F: Ledermix, group G: triple antibiotic paste (3Mix), group H: grey MTA(GMTA), group I: GMTA + blood, group J: white MTA (WMTA), group K: WMTA + blood, group L: Portland cement (PC), group M: PC + blood and group N: AH Plus. The cavities were sealed with composite and stored in water. Standardized colour measurement (VITA Easyshade compact) was performed at the following intervals: prior to (T0) and after placement of the filling (T1), 1 week (T2), 1 month (T3), 3 months (T4), 6 months (T5) and after 1 year (T6). Colour change (ΔE) values were calculated. A two-way analysis of variance was used to assess significant differences between the endodontic materials. The mean values of all groups were compared using the Tukey multiple comparison test (α = 0.05). Significant differences were detected amongst the experimental groups after 12 months (P < 0.0001). The lowest colour change values were observed in the groups N (AH Plus, 3.2 ± 1.5), A (empty, 3.8 ± 1.4), L (PC, 4.1 ± 1.7), C (calcium hydroxide, 4.7 ± 1.5), E (Ultracal XS, 5.1 ± 1.9) and J (WMTA, 7.9 ± 6.7). The most discoloration was measured in groups G (3Mix, 66.2 ± 9.9) and F (Ledermix, 46.2 ± 11.6). PC showed the best colour stability amongst the Portland cement-based materials; however, when contaminated with blood (group M), a significantly higher ΔE value (13.6 ± 4.2) was detected (P = 0.032). Materials used in endodontics may stain teeth. Therefore, the choice of material should not rely solely on biological and functional criteria, but also take aesthetic considerations into account.