RESUMO
BACKGROUND: Patient's illness perception, assessed through the Brief-Illness Perception Questionnaire (Brief-IPQ), plays a decisive role in the treatment effectiveness of a wide range of chronic diseases; nonetheless, evidence is still lacking regarding periodontitis. The aim of the present pre-post quasi-experimental study was to evaluate the change in the Brief-IPQ before and after non-surgical periodontal treatment (NST) and to evaluate its ability to foresee the efficacy of NST. METHODS: A total of 126 periodontitis participants starting NST were asked to participate in the study. The nine-item Brief-IPQ together with a full periodontal chart were recorded at baseline and at the 3-month follow up (reevaluation) after NST. Pre-post comparisons of psychometric and periodontal variables were carried out through the Wilcoxon signed-rank test (α = 0.05). A predictive model was built to test the ability of the Brief-IPQ items to foresee the efficacy of NST. RESULTS: NST led to a significant reduction in all periodontal parameters (P < 0.001); the proportion of pockets closed was 64.18%. Although the overall sum score of the Brief-IPQ remained fairly stable (P = 0.0673), significant changes occurred for items seven ("understanding") (P < 0.001) and 8 ("emotional response") (P < 0.05). The best model (R2 = 0.068, F = 2.15, P = 0.033) obtained from the multivariate linear regression analysis demonstrated that item five ("identity") (ß = 2.340, P = 0.017) and item eight ("emotional response") (ß = -2.569, P = 0.008) significantly predict the efficacy of NST (i.e., the proportion of pockets closed at reevaluation). CONCLUSIONS: NST significantly ameliorates patient's understanding and emotional burden related to periodontitis. Baseline values of perceived symptoms and emotional response are predictive for the short-term efficacy of NST.