(PR098) Discoloration Potential of Novel Topical Endodontic Anti-microbial Agents

In regenerative endodontic therapy (RET), root canal disinfection is critical in promoting pulp tissue revascularization. However, the use of certain topical antimicrobial agents, like triple antibiotic paste, can lead to crown discoloration, and negatively affecting patient satisfaction. This study investigated the discoloration potential of tigecycline (a newer and more effective tetracycline analogue that discolors teeth less than minocycline), and a novel antimicrobial that inhibits the bacterial (DHFR) gene, known as Analogue #66, to determine if these antimicrobial alternatives discolor the crown.

Methods: Forty maxillary incisors were collected and sterilized, followed by access preparations. The teeth were divided into four groups: (1) Tigecycline at 10 mg/mL, (2) Tigecycline 10 mg/ml preceded by internal pulp chamber acid etching and bonding with 35% phosphoric acid 3m Scotchbond Multi-purpose Adhesive, (3) Analogue #66, and (4) Calcium hydroxide (negative control). Root canals were treated with the respective agents, and crown color was measured weekly for six weeks using a spectrophotometer. Color change (ΔE) from baseline was calculated and compared to established perceptibility and acceptability thresholds.

Results: Both tigecycline and analogue #66 exceeded the acceptability threshold of discoloration (ΔE > 1.8) by week 2 and remained higher than controls. Internal acid etching and bonding did not improve the results for tigecycline. Calcium hydroxide exhibited no significant color change throughout the study.

Conclusion: Tigecycline at 10 mg/mL and Analogue #66 caused significant crown discoloration. Further research is required to develop protocols that prevent crown discoloration without compromising antimicrobial efficacy in the root canal environment.