Oral Diseases. 2017;1–7. | 1 wileyonlinelibrary.com/journal/odi Received: 6 November 2016 | Revised: 31 July 2017 | Accepted: 1 August 2017 DOI: 10.1111/odi.12737 ORIGINAL ARTICLE Association between periodontitis and severe asthma in adults: A case–control study Kaliane Rocha Soledade-Marques 1 | Isaac Suzart Gomes-Filho 1 | Simone Seixas da Cruz 1,2 | Johelle de Santana Passos-Soares 3 | Soraya Castro Trindade 1 | Eneida de Moraes Marcílio Cerqueira 1 | Julita Maria Freitas Coelho 4 | Maurício Lima Barreto 5,6 | Maria da Conceição Nascimento Costa 5 | Maria Isabel Pereira Vianna 3 | Frank A. Scannapieco 7 | Álvaro Augusto Cruz 8 | Adelmir Souza-Machado 8,9 © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd. All rights reserved 1 Department of Health, Feira de Santana State University, Feira de Santana Bahia, Brazil 2 Department of Epidemiology, Federal University of Recôncavo da Bahia, Santo Antônio de Jesus, Bahia, Brazil 3 Department of Preventive Dentistry, Federal University of Bahia, Salvador, Bahia, Brazil 4 Department of Biological Sciences, Feira de Santana State University, Feira de Santana, Bahia, Brazil 5 Department of Collective Health, Institute of Collective Health, Federal University of Bahia, Salvador, Bahia, Brazil 6 Oswaldo Cruz Foundation, Research Center Gonçalo Muniz - FIOCRUZ, Salvador, Bahia, Brazil 7 Department of Oral Biology, University of Buffalo, Buffalo, NY, USA 8 ProAR – Núcleo de Excelência em Asma, Federal University of Bahia, Salvador, Bahia, Brazil 9 Department of Biomorphology, Federal University of Bahia, Salvador, Bahia, Brazil Correspondence Isaac Suzart Gomes-Filho, Department of Health, Feira de Santana State University, Feira de Santana Bahia, Brazil. Email: isuzart@gmail.com Funding information Alvaro A. Cruz, Grant/Award Number: CNPq/ FAPESB - PRONEX – 6353 – PNX0018/2009 Objective: To evaluate the association between periodontitis and severe asthma, with participants in treatment for severe asthma, controlled by therapy. Methods: A case–control investigation was performed to compare 130 adults with severe asthma with 130 without asthma. Individuals with periodontitis were those with ≥4 teeth with ≥1 site with probing depth ≥4 mm, clinical attachment level ≥3 mm, and bleeding upon probing at the same site. Severe asthma diagnosis was based on Global Initiative for Asthma criteria. Results: Association between exposure to periodontitis and severe asthma was found: OR crude = 2.98 (95% CI: 1.74–5.11). When confounders were considered, the associa- tion between exposure to periodontitis and severe asthma was maintained: OR adjusted = 3.01–3.25. Individuals with periodontitis had about a threefold increased risk of severe asthma than those without periodontitis. Frequency of periodontitis in participants with severe asthma was greater than that of those without asthma (46.6% vs 22.3%, p ≤ .05). Conclusions: Association between periodontitis and severe asthma was observed. Further investigation is required to determine the direction of this relationship. It may be causal, but it may also be a consequence of the immunopathological process that characterizes asthma, or else, consequence of the medication used for treatment. KEYWORDS asthma, bronchial inflammation, epidemiology, periodontal disease, periodontitis 1 | INTRODUCTION Both periodontitis and asthma are complex diseases with high prevalence worldwide. Approximately 20% of all adults demonstrate evidence of periodontitis (Genco & Borgnakke, 2013), while asthma affects some 334 million people of all ages (GINA, 2014), 10% of which are severe (WHO, 2011). Few studies have addressed the in- fluence of periodontitis on asthma (Friedrich et al., 2006; Gomes-Filho