An in vitro evaluation of the effect of intracoronal bleaching in teeth discolored by triple-antibiotic paste

Purpose: The purpose of the study is to evaluate the effect of intracoronal bleaching agents (IBA) on discolored teeth with triple-antibiotic paste (TAP).
Methods: Twenty-six extracted maxillary incisors were discolored for 3 weeks with TAP, containing metronidazole, ciprofloxacin, and doxycycline. Following CIE L*a*b* system, colors were measured at baseline and at 1, 2, and 3 weeks. Specimens, bleached intracoronally, were randomly divided into two groups (n = 13): 35% hydrogen peroxide (HP) and 37% carbamide peroxide (CP). Color changes (ΔE) were based on the spectrophotometric measurements at baseline, 3rd, 6th, and 9th days and analyzed using analysis of variance, Bonferroni, and Student t-tests (p < 0.05).
Results: The discoloration increased from baseline to week 3 with significant difference (p < 0.05). The highest ΔE value was observed at week 3 (16.54 ± 5.90). In HP, there was no significant difference on the 6th day compared to the 3rd day (p > 0.05) but a significant difference on the 9th day (p < 0.05). In CP, ΔE was not statistically different among evaluated days. On day 9, HP had a significantly higher ΔE than CP (p = 0.032).
Conclusion: TAP caused clinically unacceptable ΔE, increasing over time (ΔE ≥ 3.3). IBA was found effective on discolored teeth. 35% HP was more effective than CP on the 9th day.