SummaryBackground and Aim: Substantial evidence supports an association between chronic infections/inflammation, and cancer. The aim of this study was to assess the effect of chronic periodontitis on head and neck squamous-cell carcinoma (HNSCC).Materials and Methods: The study population consisted of 46 patients, divided into two groups. Cases were patients diagnosed with primary HNSCC (n=26). Controls were all patients seen during the same period of time but negative for malignancy (n=20). The severity of periodontitis was assessed through clinical determination of the bleeding index, periodontal index, tooth mobility degree and alveolar bone loss (ABL) on standardized panoramic radiographs. All patients were asked to fill in a questionnaire regarding aspects of quality of life before the diagnostic was established.Results: Each millimetre of ABL was associated with >4-fold increased risk for HNSCC. The strength of the association was greatest in the oral cavity, followed by the oropharynx and larynx. The association persisted in subjects who never used tobacco and alcohol. Patients with periodontitis, whose bleeding and periodontal indices and tooth mobility values were higher, were more likely to have poorly differentiated oral cavity SCC than those without periodontitis (32.8% versus 11.5%; P = 0.038). The patients in the study group had higher values regarding the questionnaire points compared to those in the control group.Conclusions: This study suggests that chronic periodontitis is a risk factor for the development of HNSCC. These results have implications for practical and improved strategies for prevention, diagnosis, and treatment of HNSCC.