Prevalence of periodontitis: misclassification, under-recognition or over-diagnosis using partial and full-mouth periodontal examination protocols.

OBJECTIVE: The aim of this cross-sectional study was to assess the bias in estimating the prevalence of periodontitis due to partial-mouth periodontal examination protocols (PMPE) and to relate the severity and extent of periodontal damage to periodontitis misclassification when applying case definitions by Centres of Disease Control and Prevention and American Academy of Periodontology (CDC/AAP). MATERIALS AND METHODS: A full-mouth periodontal examination (FMPE) was performed in 721 adults living in North Italy to identify moderate and severe periodontitis. These results were compared with those obtained with two PMPE protocols analyzing two interproximal sites on all teeth (fMB-DL) or four interproximal sites in two random diagonal quadrants (pMDB-MDL). RESULTS: Both PMPE systems estimated the prevalence of moderate periodontitis with limited bias (-2.79% for pMDB-MDL and -3.49% for fMB-DL), whereas produced larger relative biases for severe periodontitis (-28.74% versus - 14.55%). The percentage of under-recognition of existing periodontal disease was 8.9% under fMB-DL and 15.5% under pMDB-MDL. The diagnosis of moderate and severe periodontal disease was correctly assigned to individuals with on average 8% and 30% of pathological sites, respectively. CONCLUSION: These findings suggest that PMPE systems provide high level of bias when using CDC/AAP case definitions.