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Based on a surprising new study, individuals who have more dental cavities are at lower risk of being diagnosed with head and neck cancer, as opposed to those with fewer or no dental cavities.

Dental cavities (or caries) are brought on by tooth decay. This is when the bacteria existing in the mouth make lactic acids that shred away minerals in the tooth by fermenting carbohydrates.

According to researchers from the University at Buffalo, NY, prior studies have shown the bacteria that leads to tooth decay is associated to an immune response, which may be protective against cancer.

For this study, published online in JAMA Otolaryngology - Head and Neck Surgery, the researchers set out to deduce whether a significant link between dental cavities and Head and Neck Squamous Cell Carcinoma (HNSCC) were the reason behind their initial findings.

The study included 399 patients who were all recently diagnosed with HNSCC and 221 subjects without the cancer who were all selected from the Department of Dentistry and Maxillofacial Prosthetics at Roswell Park Cancer Industry between 1999 and 2007.

Researchers examined the dental history of all patients, mainly their history of dental cavities, by measuring the number of decayed, missing and filled teeth.

From the pool of 399 patients with HNSCC, 146 (36.6%) had oral cavity squamous cell carcinoma (SCC). Oropharyngeal SCC was found in 151 (37.8%) patients, while 102 (25.6%) had laryngeal SCC.

“Caries is a dental plaque-related disease. Lactic acid bacteria cause demineralization (caries) only when they are in dental plaque in immediate contact with the tooth surface. The presence of these otherwise beneficial bacteria in saliva or on mucosal surfaces may protect the host against chronic inflammatory diseases and HNSCC. We could think of dental caries as a form of 'collateral damage' and develop strategies to reduce its risk while preserving the beneficial effects of the lactic acid bacteria,” the researchers explained.

The researchers also allude to a possible method aimed at reducing the risk of dental cavities all the while still conserving the lactic acid bacteria could be to employ mechanical plaque control, preservation of saliva and use of fluoride, as well as controlling diet and other risk factors.

"Future studies assessing the potential effects of the oral microbiome and associated immune responses on HNSCC will help elucidate the biological mechanism of the clinical association that we have observed in this study,” they said.