Reduction of viable bacteria in dentinal tubules treated with a novel medicament (Z-Mix)

BACKGROUND/PURPOSE: The 3Mix-MP formulation (a mixture of metronidazole, ciprofloxacin, and minocycline; macrogol and propylene glycol) has been used to kill residual bacteria in dentin caries. This study aimed to investigate the dentin disinfection and cytotoxicity of a novel zinc oxide (ZnO) based medicament, Z-Mix. MATERIALS AND METHODS: Z-Mix was prepared as a prefilled syringe of materials containing mainly ZnO, incorporated with amoxicillin, ciprofloxacin, and metronidazole (1 g% of each antibiotic). Drug penetration was measured at 24 hours and 72 hours. Streptococcus mutans, Lactobacillus acidophilus, or Enterococcus faecalis were inoculated into dentinal tubules for 30 days and were then subjected to Z-Mix or 0.2% chlorhexidine (CHX) for 48 hours. Viable bacteria in the dentin were determined using fluorescence staining. Their cytotoxicity against human dental pulp cells was assessed using an MTT assay. RESULTS: Z-Mix obviously diffused into dentinal tubules and the root apex, compared to the 3Mix-MP (P < 0.05). Fluorescence staining demonstrated a reduction of viable bacteria at 100 μm and 500 μm below infected cavities after treatment with Z-mix or CHX for 48 hours. Live and dead bacteria ratios indicated that Z-Mix exhibited markedly antimicrobial effects on inoculated bacteria in dentin samples (P < 0.05). There was no significant difference in the antimicrobial property between Z-Mix and CHX (P > 0.05). An acceptable level of cytotoxicity was observed in Z-Mix and its ingredients. CONCLUSION: Z-Mix, a soft shapeable paste containing a mixture of three antibiotics, is successfully. It can penetrate to the root apex and exhibits antimicrobial properties.