The clinical efficacy of pulpectomy in primary dentition relies on filling materials that exhibit robust antimicrobial activity, high biocompatibility, and a resorption profile synchronized with physiological root development. Conventional materials such as Zinc Oxide, Iodocal, and Metapex show limitations in antibacterial efficacy, especially against resistant pathogens like Enterococcus faecalis and Lactobacillus acidophilus. To resolve this, a new root canal obturating paste was formulated using a blend of calcium hydroxide, zinc oxide, and metronidazole, and this investigation sought to evaluate its antimicrobial performance against standard industry materials. An in vitro study evaluated four obturating materials: Novel Material (Calcium Hydroxide 60%, Zinc Oxide 40%, Metronidazole 2%), Premixed Zinc Oxide, Iodocal, and Metapex. The agar diffusion technique was employed to evaluate the antimicrobial efficacy against Streptococcus mutans, Staphylococcus aureus, Lactobacillus acidophilus, Enterococcus faecalis, and Candida albicans. Zones of inhibition (mm) were recorded and statistically analyzed. The novel material showed significantly higher antimicrobial efficacy against Lactobacillus acidophilus, Staphylococcus aureus, and Enterococcus faecalis (P < 0.05). Premixed Zinc Oxide demonstrated moderate effectiveness, followed by Metapex, while Iodocal showed the least activity. The addition of metronidazole enhanced the antibacterial spectrum, particularly against resistant pathogens. The novel calcium hydroxide–zinc oxide–metronidazole obturating material exhibited superior antimicrobial activity, suggesting its potential as an effective alternative in pediatric endodontics.
