To evaluate the oral health status in patients with Alzheimer dementia (AD), and the association of the disease severity with the oral findings. Methods: The study was conducted on the study group (31 AD patients) and the control group (47 healthy volunteers) from the Neurology Department of the Institute. Cognitive status was evaluated with the MMSE scoring system. Oral parameters, such as decaying, missing, filled teeth (DMFT) index and teeth present (PT) were evaluated in the patients. Oral hygiene status, denture status and mucosal lesions, including denture-induced stomatitis were also investigated. Results: The study was conducted on the study group (31 AD patients) and the control group (47 healthy volunteers). Tooth brushing and denture cleaning were irregular in 22 of 31 (70%) patients with AD. The ratio of the subjects who forgot to remove their denture during the night was significantly higher in the study group than in the control group (p < 0.001). In this study, decreased cognitive functions in AD patients have been demonstrated to result in a deterioration of denture care and increased denture-related mucosal lesions. Conclusions: These findings were considered due to decreased denture care including the non-removal of the denture in the night in the patients with decreased cognitive functions. © 2010 The Gerodontology Society and John Wiley & Sons A/S.