Use of a triple antibiotic solution affects the healing process of intentionally delayed replanted teeth in mice

Objective: A mixture of ciprofloxacin, metronidazole, and minocycline (3Mix) has been reported to be effective against oral bacteria from carious and endodontic lesions in vitro and in vivo. The objective of this study was to establish an animal model using mice for the application of 3Mix following intentionally delayed tooth replantation and to investigate the effects of 3Mix on the healing process of dental pulp and periodontal tissues. Methods: Upper first molars of ICR mice were extracted, immersed in 3Mix solution at different concentrations for 5-60 min with or without the use of a transfer solution (phosphate buffer solution (PBS)), in addition to transfer solution alone, and subsequently repositioned in the sockets. Immunohis-tochemistry for nestin and Ki-67, histochemistry for TRAP, and TUNEL assay were performed to assess pulpal healing during days 7-21. Results: Increased apoptosis was observed in the PBS group at week 1, followed by cell proliferation at week 2, and tertiary dentin and/or bone-like tissue formation at week 3. In contrast, nestin-positive, newly differentiated, odontoblast-like cells began to align along the pulp-dentin border following the appearance of Ki-67- and TUNEL-positive cells during weeks 1-2 in the 3Mix groups, suggesting that pulpal healing was accelerated. Severe root ankylosis was observed exclusively in the 3Mix groups. Rinsing with PBS before replantation partially rescued the viability of the periodontal ligament, but pulpal healing was delayed. Conclusions: The application of 3Mix promotes pulpal regeneration of intentionally delayed replanted teeth; however, its use may induce severe damage to periodontal tissues.