When we see patients with bad dental caries, we tend to think they are more at risk of developing various diseases when compared to those without -- but this may not be the case when it comes to head and neck cancers.
According a recent study published in JAMA, dental cavities can act as a protective mechanism against squamous cell carcinomas of the head and neck. I would have thought the opposite to be true, but investigators speculate that the association between dental caries and cancer may be related to a specific immune response to decay-causing bacteria in dental plaque.
The study assessed 620 adults at a dental and maxillofacial prosthetics clinic at a comprehensive cancer center. Patients with the most dental caries had one-third the risk for head and neck squamous cell carcinoma (HNSCC) when compared with those patients with few or no dental caries. What's even more interesting is that patients with more dental crowns were at a significantly lower risk for this type of cancer.
So what is the secret behind tooth decay and how is this protecting patients from HNSCC? Dr. Mine Tezal, DDS, PhD, from the State University of New York at Buffalo suggests that lactic acid bacteria may be the key:
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.
It is important to note that while there seems to be an association between cavities and a reduced risk of HNSCC, studies have shown an increased risk for HNSCC for those with chronic inflammation of the gums or periodontitis when Gram-negative anaerobic bacteria is present.
While researchers and practitioners alike are not encouraging patients to have bad oral hygiene -- potentially leading to dental caries and gum disease -- further investigation regarding the effects of lactic acid bacteria on the immune system and its effect on cancer may be worth pursuing.