Specimens were randomly divided into three groups, according to the type of bile acid used in the erosive challenge (n = 8). The bile acids were those found in the clinical study. Taurocholic and glycocholic acids (Sigma Aldrich, Saint-Louis, USA) were used to prepare three solutions in the pharmacy laboratory in UPF; Taurocholic 1µM (pH = 5); Taurocholic 10µM (pH = 5); and taurocholic + glycocholic 10µM (pH = 6).
The erosive challenge consisted of immersing each specimen individually in 10 mL of the bile acid solution for a total time of 6 minutes, to simulate an episode of reflux (Derceli Jdos et al. 2016) . At intervals of 2 minutes of immersion, the specimen was removed from the solution and washed with distilled water for 15 seconds.
The erosive challenge consisted of immersing each specimen individually in 10 mL of the bile acid solution for a total time of 6 minutes, to simulate an episode of reflux (Derceli Jdos et al. 2016) . At intervals of 2 minutes of immersion, the specimen was removed from the solution and washed with distilled water for 15 seconds.