Calcium hydroxide can induce and promote the formation of reparative dentin. When the superficial layer of dental pulp comes into contact with calcium hydroxide, it undergoes destruction and decomposition. The necrotic layer stimulates the deep dental pulp tissue and activates its reparative potential. Stromal cells and fibroblasts proliferate, accompanied by fibrous hyperplasia. The disorganized fibers gradually arrange perpendicularly to the superficial layer and extend deep into the collagen matrix. Fibroblasts then differentiate into odontoblasts, which produce tubular and osteoid dentin. Subsequently, calcium salts are deposited, the dentin bridge undergoes calcification, and the coagulated necrotic layer disappears completely.

In addition, due to its strong alkalinity, calcium hydroxide exerts a certain bactericidal effect on bacteria in carious dentin. It can control infection and alleviate pain during root canal treatment, with efficacy significantly superior to traditional medicaments such as formaldehyde cresol and camphor phenol.

The antibacterial activity of calcium hydroxide is mainly attributed to hydroxide ions. These ions rapidly trigger lipid peroxidation and increase the permeability of bacterial cell membranes, cause protein denaturation and enzyme inactivation, and damage bacterial DNA, ultimately leading to bacterial death.

Calcium hydroxide has been widely used in conservative dentistry. Its therapeutic mechanism has been thoroughly investigated and its clinical efficacy well recognized. In recent years, it has gained increasing attention as an intracanal disinfectant.