Disadvantage of minocycline in triple antibiotic paste used for disinfection of root canal prior to revascularization is:

Triple antibiotic paste Consists of metronidazole, ciprofloxacin, and minocycline in a macrogol propylene glycol ointment.  It is inserted into the canal with a sterile lentulospiral and left in the canal for 2-4 weeks. Advantages: Very effective in elimination of intracanal microbes. Broad spectrum action. Easy to prepare as ingredients are easily prepared. Disadvantages of Triple Antibiotic Paste: Difficult to test the antimicrobial effectiveness in endodontic models due to absence of an inactivator to prevent the carryover effect. Combination of bactericidal and bacteriostatic antibiotic is not rational scientifically. Tetracycline analogs like minocycline can cause discoloration of tooth due to diffusion into dentinal tubules. Hence the mix should never be left in the coronal pulp chamber.