<jats:p><jats:bold>Background</jats:bold>: Dementia is a multi‐etiologic syndrome characterized by multiple cognitive deficits but not always by the presence of cognitive impairment. Cognitive impairment is associated with multiple non‐modifiable risk factors but few modifiable factors. Epidemiologic studies have shown an association between periodontitis, a potentially modifiable risk factor, and cognitive impairment. The objective of this study is to determine whether clinical periodontitis is associated with the diagnosis of cognitive impairment/dementia after controlling for known risk factors, including age, sex, and education level.</jats:p><jats:p><jats:bold>Methods:</jats:bold> A case‐control study was conducted in Granada, Spain, in two groups of dentate individuals aged >50 years: 1) cases with a firm diagnosis of mild cognitive impairment or dementia of any type or severity and 2) controls with no subjective memory loss complaints and a score >30 in the Phototest cognitive test (screening test for cognitive impairment). Periodontitis was evaluated by measuring tooth loss, plaque and bleeding indexes, probing depths, and clinical attachment loss (AL).</jats:p><jats:p><jats:bold>Results:</jats:bold> The study included 409 dentate adults, 180 with cognitive impairment and 229 without. A moderate and statistically significant association was observed between AL and cognitive impairment after controlling for age, sex, education level, oral hygiene habits, and hyperlipidemia (<jats:italic>P</jats:italic> = 0.049). No significant association was found between tooth loss and cognitive impairment.</jats:p><jats:p><jats:bold>Conclusion:</jats:bold> Periodontitis appears to be associated with cognitive impairment after controlling for confounders such as age, sex, and education level.</jats:p>