Accuracy of partial-mouth examination protocols for extent and severity estimates of periodontitis: a study in a Chinese population with chronic periodontitis.

BACKGROUND Partial-mouth periodontal examination (PMPE) has been widely used in periodontal epidemiologic studies. In this study, the authors evaluate the accuracy of extent and severity estimates from PMPE protocols in a Chinese population. METHODS The study enrolled 200 individuals with periodontitis, ages 22 to 64 years. Full-mouth examination was performed to determine probing depth (PD), attachment loss (AL), and bleeding on probing (BOP) at mesio-buccal (MB), mid-buccal (B), disto-buccal (DB), mesio-lingual (ML), mid-lingual (L), and disto-lingual (DL) sites per tooth. Extent and severity estimates from 15 PMPE protocols were derived from and compared to full-mouth data. Relative bias (RB) and intraclass correlation coefficients (ICCs) were calculated. Bland-Altman plots were used to evaluate the agreement patterns across disease levels. RESULTS Of the 15 PMPE protocols, the random half-mouth six-sites per tooth (r6sites) protocol performed best in both extent (AL ≥ 2, ≥ 4, or ≥ 6 mm; PD ≥ 4 or ≥ 6 mm; and BOP) and severity (AL and PD) estimates, with RB within 5.0% and ICCs ≥ 0.950 in most cases. MB-B-DB and MB-B-DL protocols generally resulted in RB within 20.0% for extent and within 5.0% for severity. Protocols involving only interproximal sites (MB-DB, MB-DL, and MB-DB-ML-DL) showed good accuracy in AL (RB within 20.0% for extent and within 3.0% for severity), but overestimated PD (RB 12.5% to 54.2% for extent and >10.0% for severity). The community periodontal index teeth protocol caused severe overestimation of up to 110.4% for extent and 14.6% for severity. CONCLUSION The r6sites protocol is best for assessing extent and severity for AL, PD, and BOP under the study conditions.