Tooth loss is not only very unappealing, it is also extremely unhealthy: a new research study published in the Cancer Epidemiology, Biomarkers and Prevention journal found a tight connection between tooth loss and increasing risks of developing 3 forms of cancer (esophageal, head and neck, and lung).

Until now, the team from Aichi Cancer Center in Nagoya and Nagoya University Graduate School of Medicine, Japan, could only guess that bacterial infection and inflammation caused by poor oral hygiene and eventually leading to tooth loss could also account for one of the causes for the inset of these cancers. A 2008 research study made a connection between periodontal disease and increasing risks for stroke and heart disease. Tooth loss can also be a signal of bad habits (smoking, alcohol consumption, poor diet) that increase cancer risks.

"Tooth loss is a common consequence of chronic bacterial infection and may, therefore, serve as a surrogate for chronic infection and inflammation, which in turn may be important to the pathogenesis of cancer", said lead author of the study, Dr. Akio Hiraki, from the Aichi Cancer Center.

The team assessed the incidence of 14 types of cancers and rates of tooth loss in 5,240 cancer patients; those rates were analyzed together with data gathered from 10,480 cancer-free subjects.

Tooth loss was connected to a 136% rise in the risk of developing esophageal cancer, 68% in the case of head and neck cancer and 54% in the case of lung cancer. The incidence of cancer was also proportionally connected to the number of already lost teeth. The research took into account other risk factors like smoking and alcohol consumption.

"Smaller studies have linked tooth loss to different cancers, but this is the largest study to date and the first conducted within an Asian population. This is also the first study to show a link to lung cancer", wrote the authors.

Age and gender were the main factors affecting the link between tooth loss and cancer risks. Tooth loss was mostly associated with head and neck and esophageal cancers in women and men younger than 70 years of age.