Purpose: Different periodontitis case definitions have been used in clinical research and epidemiology. The aim of this study was to determine more accurate criterion for the definition of mild and moderate periodontitis case to be applied to head and neck cancer individuals before radiotherapy.
Methods: The frequency of periodontitis in a sample of 84 individuals was determined according to different diagnostic criteria: (1) Lopez et al. (2002);(2) Hujoel et al. (2006); (3) Beck et al. (1990); (4) Machtei et al. (1992); (5) Tonetti and Claffey (2005); (6) and Page and Eke (2007). All diagnosis were based on the clinical parameters obtained by a single calibrated examiner (Kw = 0.71). The individuals were evaluated before radiotherapy. They received oral hygiene instructions, and the cases diagnosed with periodontitis (Page and Eke 2007) were treated. The gold standard was the definition 6, and the others were compared by means of agreement, sensitivity (SS), specificity (SP), and the area under ROC curve. The kappa test evaluated the agreement between definitions.
Results: The frequency of periodontitis at baseline was 53.6 % (definition 1), 81.0 % (definition 2), 40.5 % (definition 3), 26.2 % (definition 4), 13.1 % (definition 5), and 70.2 % (definition 6). The kappa test showed a moderate agreement between definitions 6 and 2 (59.0 %) and definitions 6 and 1 (56.0 %). The criterion with higher SS (0.92) and SP (0.73) was definition 1.
Conclusion: Definition 1 was the most accurate criterion to case periodontitis definition to be applied to head and neck cancer individuals.