Dental Caries, also known by the general public as cavities in teeth, is still one of the most common diseases globally. The World Health Organization estimates that 2.3 billion adults and 560 million children are affected by dental caries. The WHO also notes that caries is to a great extent preventable with a diet very low in simple sugars and adequate cleaning¹. But that has proven to be easier said than done.

We know a considerable amount of people have caries, so what could be the possible hypotheses be behind them? This blog will specifically cover the microbial challenge to teeth. Diving in, first there is the Specific Plaque Hypothesis, second is the Nonspecific Plaque Hypothesis, and lastly the Ecological Plaque Hypothesis. Let’s dig a little deeper into each.

1. The Non-Specific Plaque Hypothesis:
   • Essentially different combinations of bacteria are responsible for causing caries. So no single strain of bacteria is the causative agent².
   • This Hypothesis has multiple papers published on the topic featuring Else Theilade and Harald Löe who also published Experimental Caries in Man in 1970
2. The Specific Plaque Hypothesis:
   • Just as it sounds, this hypothesis assumes that only a few different bacteria are the culprits for causing cavities e.g. Streptococcus mutans or Streptococcus sobrinus amongst others³.
   • This Hypothesis was posed in 1992 in an article written by W.J Loesche
3. The Ecological Plaque Hypothesis:
   • The ecological hypothesis might be a little trickier to wrap your head around.
   • It basically states that the teeth are in a constant flux of good and bad bacteria.
   • When bad conditions persist e.g., acidic environments and/or poor hygiene, the caries causing bacteria are allowed to thrive and destroy tooth structure.
   • The earliest publication I found for this theory was from 1994⁴.

Which Hypothesis is right?

That’s for you to decide on your own, but usually I find the truth to be somewhere in the middle of each side of the story. These hypotheses can also be applied to how bacteria help to cause Gingivitis/Periodontal disease. Feel free to comment your thoughts!

1. WHO TECHNICAL INFORMATION NOTE OCTOBER 2017 Sugars and Dental Caries. https://apps.who.int/iris/bitstream/handle/10665/259413/WHO-NMH-NHD-17.12-eng.pdf?sequence=1.
2. Theilade E. (1986). The non-specific theory in microbial etiology of inflammatory periodontal diseases. Journal of clinical periodontology, 13(10), 905–911. https://doi.org/10.1111/j.1600-051x.1986.tb01425.x
3. Loesche W. J. (1992). The specific plaque hypothesis and the antimicrobial treatment of periodontal disease. Dental update, 19(2), 68–74.
4.  Marsh P. D. (1994). Microbial ecology of dental plaque and its significance in health and disease. Advances in dental research, 8(2), 263–271. https://doi.org/10.1177/08959374940080022001

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