Predictors of Cancer and Diabetes: Oral Microbiota

Written by Manal Usmani and Edited by Sorina Long

Just like in our guts, we have microorganisms residing in our mouths, collectively named oral microbiota. These beneficial microorganisms help with initial food digestion and provide immunity against harmful microbes in food. Conversely, the unfavorable types, which use sugar as a fuel source, can cause disease in the oral cavity. If there is food stuck between teeth for a prolonged period, microorganisms such as Streptococcus mutans can consume it and leave behind acids on your teeth as a waste product [1]. These acids can deteriorate teeth, eventually leading to cavities, which can harbor more bacteria. At birth, we have a certain ratio of helpful to harmful microorganisms, but cavities can alter this ratio by providing an environment where harmful types thrive and increase in number. Recent studies have found that specific ratios of microorganisms can be a risk factor or sign of systemic disease in the rest of the body, demonstrating the effect that oral health has on other body functions [2].

Gum disease, specifically periodontitis, is well-established as a risk factor for the development of diabetes in adults. Periodontitis is a severe gum infection that can have other major effects such as loss of bone surrounding teeth. Characterization of microorganisms residing in the mouth revealed increased levels of two harmful bacteria, P. gingivalis and P. intermedia, in those with periodontitis who developed diabetes later on in life [3]. A similar study expanded on this discovery, looking at the correlation between levels of bacteria in the mouth as a prediction tool for certain types of cancer. . An abundance of certain families of microorganisms, such as Lactobacillus, and a decrease in the amount of others such as Neisseria elongata, can indicate risk for developing cancer in some populations, and quantities have been correlated with patients experiencing cancer [4] [5]. As such, there is almost double the number of Lactobacillus present in oral rinse samples of those with colorectal cancer compared to those without it [4]. Conversely, Neisseria elongata is significantly decreased in patients with pancreatic cancer [5]. More research needs to be conducted to identify the correlation between these findings, but there is a promising future for oral microbiota characterization as a technique for cancer prediction and diagnosis.

Oral microbiota affects functions inside the mouth and throughout the rest of the body,  is why healthy teeth and gums are seen as a precursor to a healthy body. However, most people will encounter some type of oral disease in their lifetime. To address this widespread need of oral health specialists, dentistry was created as a branch of the medical field serving to treat and prevent disease in the mouth. We are not in control of the microbiota we are born with, but we can engage in preventative measures to minimize cavities and gum disease that are known to alter the existing population of microorganisms. Your dentist most likely emphasizes brushing and flossing as the most effective measures against having to visit them again for a procedure. Electric toothbrushes, specifically, are recommended by dentists because they can achieve a higher level of cleanliness in the same period of time when compared to manual toothbrushes [6]. Furthermore, flossing is essential before brushing your teeth since food can be stuck in small spaces that the brush is not able to reach. Many oral diseases are caused by a lack of attention to oral hygiene, and most are preventable through the use of a regular cleaning routine.

References:

1. Johansson, I., Witkowska, E., Kaveh, B., Lif Holgerson, P., Tanner, A. C. (2016). The Microbiome in Populations with a Low and High Prevalence of Caries. Journal of DentalResearch.95:80-86.
2. Chen, T., Yu, W. H., Izard, J., Baranova, O. V., Lakshmanan, A., Dewhirst, F. E. (2010). The Human Oral Microbiome Database: a web accessible resource for investigating oralmicrobe taxonomic and genomic information. The journal of biological databases and curation, 10:1085-1093.
3. Preshaw, P. M., Alba, A. L., Herrera, D., Jepsen, S., Konstantinidis, A., Makrilakis, K., Taylor, R.(2012). Periodontitis and diabetes: a two-way relationship. Diabetologia, 55:21-31.
4. Kato, I., Vasquez, A. A., Moyerbrailean, G., Land, S., Sun, J., Lin, H. S., Ram, J. L. (2016). Oral microbiome and history of smoking and colorectal cancer. Journal of Epidemiological Research,2:92-101.
5. Farrell, J. J., Zhang, L., Zhou, H., Chia, D., Elashoff, D., Akin, D., Paster, B. J., Joshipura, K., Wong, D. T. (2012).Variations of oral microbiota are associated withpancreatic diseases including pancreatic cancer. Gut, 61:582-588.
6. Kulkarni, P., Singh, D. K., Jalaluddin, M. (2017). Comparison of Efficacy of Manual and Powered Toothbrushes in Plaque Control and Gingival Inflammation: A Clinical Study among the Population of East Indian Region. Journal of International Society of Preventive & Community Dentistry,7:168-174.