Which cells are responsible for internal root resorption of a tooth?

Internal root resorption is mediated by odontoclasts (multinucleated, osteoclast-like giant cells) that become activated within the pulp space — often following pulpal inflammation or trauma — and resorb dentin from the inside of the root outward, producing the classic radiographic appearance of a well-defined, often ballooning radiolucency centered within the root canal space.