Periapical Index
Also written as: PAI — Periapical Index
A five-point radiographic scoring system (PAI) used to classify the health or degree of periapical pathology observed at a tooth root apex on a periapical radiograph.
Full Definition
The periapical index (PAI) is a validated ordinal scale developed by Ørstavik et al. that assigns a score from 1 (normal periapical structures) to 5 (severe periodontitis with exacerbating features) based on the radiographic appearance of periapical bone. It is widely used in endodontic research and clinical audit to standardise the assessment and reporting of periapical status. Editors working on endodontic research manuscripts must ensure PAI scores are presented as integers and that the scale is defined or cited on first use. 'PAI' should be expanded to 'periapical index (PAI)' on first reference.
Usage
Usage note: PAI scores must always be presented as whole numbers (1–5). Spell out 'periapical index (PAI)' on first reference. Cite the original Ørstavik et al. source in research publications.
In Context
- "Pre-operative periapical index (PAI) scores ranged from 3 to 5, indicating the presence of periapical pathology in all treated teeth." — Endodontic research manuscript
- "At the one-year recall, PAI scores had decreased to 1 or 2 in 87% of cases, indicating successful healing." — Clinical trial results section