The combination of calcium hydroxide with camphorated monochlorophenol (CMCP) is most effective for apexification in blunderbuss canals due to its potent antimicrobial effect and ability to induce hard tissue formation. Calcium hydroxide promotes apical barrier formation by stimulating mineralized tissue growth, while CMCP enhances disinfection in the wide, open apex, reducing bacterial load effectively. This synergy facilitates proper apex closure and creates a favorable environment for subsequent root canal treatment. Other materials like MTA are excellent for apexification but may be less efficient in decontamination at an initial stage in a blunderbuss canal setting.

Reference: Grossman’s Endodontic Practice, 13th Edition.