Method: Eighteen (N = 18) bovine incisors were randomly divided into groups: G1: placebo (n = 8) and G2 = hydrogen peroxide 35% (n = 10). All specimens had the lingual surface (enamel and dentin) removed with water sandpaper, granulation 180. Buccal dentin was preserved and buccal enamel suffered wear to standardize the thickness of the specimens at 3.5 mm. Preparation of samples involved setting it with acrylic resin. The bucal and pulp were isolated, preventing the permeation of other materials in other ways. Gels (G1) or (G2) were applied on the labial enamel side of the specimens and the maximum permeation was 3600 seconds. This method was repeated three times (T1, T2 e T3) with each specimen, being a week the gap time. The microelectrode was located in the pulp chamber and was calibrated to detect H2O2 and measure the peroxide.
Result: : Analysis of variance (ANOVA) demonstrated difference between the permeation of hydrogen peroxide and placebo (p = 0.01). During the study, electrochemical analysis did not identify any electrical current (nA) for placebo, however hydrogen peroxide was identified with median time to the beggining of detectable molecules in the pulp chamber, 1148 sec (i=1,024 nA) Regarding the measurement repetition , the average time to permeation were: T1= 1841 sec, T2= 1094 sec and T3= 510 sec. T1 differ to T2 and T3 (p = 0.0005), however T2 to T3 was similar (p> 0.05).
Conclusion: The electrochemical analysis by microelectrode is effective for detecting peroxide molecules within the pulp camera. The difference between the moments of detection indicate that the permeability across tooth structures suffers changes due each passage of hydrogen peroxide, the average time to reach the pulp chamber decreases.