Oral flora and oral health issues


Dental caries, gum inflammation, and periodontal disease are all oral health issues. Oral health issues always arise from bacterial infections within the oral flora of your mouth.

Oral flora

The mouth is colonised by 200 to 300 bacterial species. This is also called the oral flora. Similar to the human gut flora, the oral cavity of a new-born baby does not contain any bacteria but becomes quickly colonised with oral bacteria.

Certain bacteria species of our oral flora can cause dental caries, gum inflammation, and periodontal disease. The starting point of all these different oral health issues is the formation of dental plaque.

Dental plaque

Dental plaque is a biofilm consisting of oral bacteria of our oral flora that grow on surfaces within the mouth. At the beginning this biofilm is soft and sticky and can easily be cleaned. However, if plaque is not removed it can become hard when minerals such as calcium in the saliva combine with it. Hard dental plaque is also called tartar or and dental calculus and is pale yellow or even brown. Tartar cannot be removed easily, only by professional dental cleaning.

Dental plaque causes:

  • Dental caries (Tooth decay) and
  • Gum inflammation (Gingivitis)
    • Periodontal disease (Peridontitis) is a result of gum inflammation

Actually, only a very limited number of bacteria species from our oral flora participate in oral health issues. For example, dental caries is caused by one single bacterial species, called Streptococcus mutans.

How is dental plaque causing dental caries?

Only if the formed dental plaque (or tartar) contains a certain bacterium (Streptococcus mutans) it can cause caries. It is actually very surprising that caries is only caused by one single bacterial species!

Caries (also called tooth decay) is characterised by acid demineralization of the enamel, which can progress to further breakdown of the more organic, inner dental tissue (dentin). Various factors influence whether you will get caries or not, for example fluoride exposure, sugar consumption, how good (or bad) you clean your teeth, and the composition of your oral flora.

How is dental plaque causing gum inflammation (gingivitis)?

Gum inflammation (gingivitis) is a response of your body to the bacteria contained in the plaque. Certain bacteria can induce a localised inflammation of the gum tissue, called gum inflammation or gingivitis. Inflamed gums are red, swollen and can easily bleed whilst brushing or flossing. Next to areas of inflammation, plaque is often visible on the surfaces of surrounding teeth.

Gum inflammation leads to periodontal disease

If this localised gum inflammation (gingivitis) is continuing for an extended period of time, this might lead to a spreading of the infection towards the supporting tissues. This progression of the gum inflammation, eventually reaching the underlying bone, is called periodontal disease.  Periodontal disease or periodontitis is an inflammation of the tissues which support teeth and attach them to the jaw. It leads to bone destruction around the teeth in the jaw.

How you can avoid the formation of dental plaque and tartar

Mouth hygiene is the key for reducing plaque formation and removing newly formed plaque. In order to control plaque formation and remove newly formed plaque, you need to brush your teeth at least twice a day, with the right brushing technique.

Furthermore, it is important to interdental aids, like dental floss, interdental brushes, and dental sticks. In cases were a lot of solid plaques (tartar) are already present the only way to remove it is professional dental cleaning.

Another way to control plaque formation is the use of mouthwash. However, mouthwashes should not be used too often, as they can actually increase bacterial activity in the mouth or stain teeth and gum. Using mouthwash is also a good way to reduce a bad breath. The two most effective mouthwashes are essential oil-based and chlorhexidine-based mouthwashes (see below).

A word on fluoride

Back in the 1980s it became clear that fluoride can help to control caries. The fact that today so many stories are circulating about bad, unhealthy fluoride can only be explained by conspiracy theories, or – how they are called nowadays – fake news.

The truth is that fluoride can inhibit tooth decay (caries) by inhibiting demineralisation of the teeth. Actually, fluoride – together with calcium from the saliva – can remineralise the tooth by forming fluorhydroxyapatite, which naturally forms the basic structure of our bones and teeth. That means fluoride can literally repair teeth that are affected by tooth decay (caries).

Keep in mind that caries is caused by the bacterium Streptococcus mutans. Fluoride might also work directly by inhibiting virulence factors of Streptococcus mutans, like acid production and glucan synthesis, which are critical for its (nasty) biological activity.

If you want to know more about what I think about mouth hygiene, read this blog post here