Bulk microbial and host cell macromolecules

Bulk microbial and host cell macromolecules exposed to high pH and Ca2+ refers to the collective biological components—including proteins, lipids, and nucleic acids—of both pathogenic microorganisms and necrotic host tissues within the dental root canal system. These macromolecules are the primary substrates for the chemical action of calcium hydroxide, a gold-standard medicament in endodontic therapy. The high alkalinity (pH approximately 12.5) provided by the hydroxyl ions induces non-specific damage such as protein denaturation and membrane lipid peroxidation, effectively neutralizing bacterial toxins and disinfecting the canal space (Siqueira & Lopes, 1999). Simultaneously, the presence of calcium ions supports the formation of mineralized tissue, such as dentin bridges, by influencing host cell activity and promoting a favorable environment for repair (Mohammadi & Dummer, 2011). While highly effective for broad-spectrum disinfection and tissue dissolution, its action is non-selective and can affect any biological material in the vicinity, necessitating careful clinical application to avoid damage to healthy periodontal tissues.

Other names

Bacterial proteins and lipidsHost necrotic tissueMicrobial cell wall componentsEndodontic substratesNecrotic pulp macromolecules

The therapeutic action is driven by the dissociation of calcium hydroxide into hydroxyl ions and calcium ions. Hydroxyl ions create a highly alkaline environment (pH ~12.5) that induces lipid peroxidation of bacterial membranes, protein denaturation, and DNA damage, leading to broad-spectrum antimicrobial activity and the inactivation of bacterial endotoxins. Calcium ions contribute to the induction of hard tissue formation by stimulating alkaline phosphatase activity and reacting with carbonate ions to form calcium carbonate, which serves as a scaffold for mineralization.