Comparative Evaluation of Activated and Nonactivated Microbubbles on the Efficacy of Bleaching Agents

Intracoronal bleaching serves as a conservative option for nonvital teeth that exhibit discoloration. Hydrogen peroxide (H₂O₂) is frequently utilized in bleaching processes owing to its capability to produce free radicals. The main drawbacks of the currently available bleaching agents are the occurrence of cervical resorption and the multiple dental visits to achieve the desired result. Therefore, in our study, to address the limitations associated with cervical resorption and extended treatment duration for badly stained teeth, an attempt was made to incorporate a whitening agent (35% H₂O₂) with microbubbles.

This study aimed to compare and evaluate the effect of activated and nonactivated microbubbles on the efficacy of bleaching agents.

Forty-five human central incisors were collected and divided into three groups: Group I (HP), H₂O₂ plain (n = 15) (Control); Group II (HPM), H₂O₂-infused microbubbles without ultrasonic activation (n = 15) (experimental group); and Group III (HPMU), H₂O₂-infused microbubbles with ultrasonic activation (n = 15) (experimental group). The crowns were artificially stained. Microbubbles containing 35% H₂O₂ were generated using the probe sonication method. The bleaching agent H₂O₂ plain (0.04 mL) was syringed into the pulp chamber in group I, while H₂O₂-infused microbubbles (0.04 mL) were syringed into group II and group III. Group III was further activated ultrasonically. The evaluation of color shade differences was conducted using the Vita Lumin shade guide at three time points: baseline, day 7, and day 14.

Data regarding color change using Vita shade were investigated for normality using the Kolmogorov Smirnov test and assessed a non-normal distribution. Intergroup comparisons at each particular time interval (baseline, day 7, and day 14) were analyzed using the Kruskal-Wallis H test followed by multiple pairwise comparisons using the Adjusted Bonferroni post hoc test. Intragroup comparisons between different time intervals were analyzed using related samples from Friedman's test followed by multiple pairwise comparisons using the post hoc Dunn test. The level of statistical significance was determined at P < 0.05. There was no statistical difference in the baseline values of all three groups. Group I (HP) exhibited an average increase of three Vita Lumin shade tabs on day 7 and day 14, respectively, whereas Group II (HPM) exhibited an average increase of six and four Vita Lumin shade tabs on day 7 and day 14, respectively, and Group III (HPMU) exhibited an average increase of 10 and 3 Vita Lumin shade tabs on day 7 and day 14, respectively.

Microbubbles containing H₂O₂ were more efficient and faster than plain H₂O₂ for bleaching, and the efficacy of bleaching was enhanced when activated using ultrasonic technology.