IN-VITRO COMPARISON OF VARIOUS TYPES OF SODIUM PERBORATE USED FOR INTRACORONAL BLEACHING OF DISCOLORED TEETH

Fifty-eight extracted incisors were artificially stained to compare th e efficacy of sodium perborate preparations used for intracoronal blea ching. All teeth were bleached for a 6-day period and the bleaching pa stes replaced at days 1 and 3 (walking bleach technique). Sodium perbo rate-monohydrate, trihydrate, or tetrahydrate in conjunction with 30% H2O2 as well as tetrahydrate, either mixed with H2O or prepared as an experimental gel, were placed intracoronally at a level of 1-mm below the vestibular cementoenamel junction. Standardized slides were used t o evaluate the color changes during bleaching. Success rates between 4 6 and 77% could be achieved, but no significant differences in final b leaching results between any of the sodium perborate types were observ ed. The use of the experimental gel resulted in comparable esthetic re sults (54%), although the portion of tetrahydrate in the gel was lower than that of the other preparations. In contrast to general recommend ations that bleaching agents be left for 3 to 7 days in the access cav ity before replacement, shorter bleaching intervals did not seem to af fect the success.