Primary teeth differ completely from adult teeth in that their roots physiologically resorb as the permanent teeth underneath them move upwards. This biological process directly limits the materials that can be used in primary tooth root canal treatment. Gutta-percha and resin-based root canal fillings used in adults cannot be absorbed by the body. If these are used in a primary tooth, these materials remain intact in the bone when the root resorbs, blocking the path of the permanent tooth underneath and causing it to erupt crookedly or remain impacted. Therefore, in primary tooth root canal treatment, only special pastes containing zinc oxide eugenol, calcium hydroxide, or iodoform, which are biologically compatible with the body and can spontaneously resorb in parallel with root resorption, must be used.
