Calculus-like deposit at apex of tooth with refractory apical periodontitis.

It is generally accepted that bacteria in or outside the root canal are the reason for apical periodontitis and endodontic failures. This case report presents a 60-year-old woman with a periapical lesion and a fistulous tract which did not respond to conventional root canal treatment. During periapical surgery, granulomatous tissue was removed and a calculus-like deposit was observed on the root surface. A radicular cyst was diagnosed. Nine months after this calculus-like deposit had been removed and the cyst enucleated, complete recovery of the bone had occurred. It is suggested that the presence of the calculus-like deposit at the apex of the tooth or its effects may in part have delayed the healing of the periapical inflammation in spite of apparently adequate endodontic treatment.