Radiographic follow-up of periapical status after endodontic treatment of teeth with and without apical periodontitis.

Objectives: The aim was to assess objectively the rate of changes in periapical status after endodontic treatment in relation to preoperative radiographic status (Periapical Index Score, PAI) and to tooth type.

Material And Methods: Radiographic data from a total of 1,410 teeth in seven prospective clinical studies was pooled. The periapical status was evaluated blindly using the PAI scoring system. The longest follow-up period was 4 years; intervals between controls varied from 3 months to 1 year.

Results: Teeth with preoperative PAI score 1 maintained excellent periapical health throughout. Teeth with preoperative PAI score 2 showed some impairment in health over the first 6 months, but improved to approach 95 % healthy teeth at 2 years of observation. Teeth with PAI 3-5 at the start showed significant improvement at 3 months; 27 % were considered healthy (PAI 1 or 2) increasing to 41 % after 1 year. Improvement of periapical status was slower in PAI groups 4 and 5 compared with PAI 3 during the first year. After 2 years, improvement continued similarly in all preoperative PAI 3-5 groups of teeth. Upper lateral incisors showed the poorest healing rate.

Conclusions: Healing of pre-existing periapical lesions is most pronounced from 3 months to 2 years. Teeth with initially healthy periapical structures predictably maintain good periapical health. Maxillary teeth, especially lateral incisors, showed poorer healing rates than mandibular teeth.

Clinical Relevance: Radiographic healing rates may vary among tooth groups within the dentition. Periapically healthy teeth that are root filled may not need postoperative controls.