Apexification: case report.

Apexification is a process/procedure well recognized and accepted by clinicians and researchers alike. Calcium hydroxide is most commonly used to induce an apical hard tissue barrier which may be composed of different tissues but its mechanism of action is still unknown. The epithelial cell rests of Malassez have been implicated in apexification although case reports exist which apparently dispute this. The following case report demonstrates an unusual case of apexification following root filling, surgery and retreatment where the role of the epithelial cell rests of Malassez is discussed.