Epidemiological data support evidence that poor dental status increases oral cavity cancer risk especially among heavy alcohol consumers, but the causality of this finding is unclear. The enzymatic conversion of ethanol by the physiological oral microflora may lead to an accumulation of the highly carcinogenic intermediate acetaldehyde. This study was conducted to evaluate the role of dental status on the microbial production of acetaldehyde from ethanol in saliva. The microbial acetaldehyde production from ethanol was related to the dental score in 132 volunteers. After adjustment for smoking, alcohol consumption, age and gender, poor dental status was shown to lead to an approximately twofold increase in salivary acetaldehyde production from ethanol (P=0.02). Our results could be an important factor underlying the role of poor dental hygiene and status in oral cancer risk associated with ethanol drinking.