Streptococcus mutans the oral microrganism on the teeth

Recently, I saw a student of mine wearing hood, and knowing quite sure that it was unusual of him, so I called to inquire about it. When he got closer to me, I realized that his mouth had swollen up a bit, I jokingly asked him if he fought recently, but he just tried to mumbled few words out that he never did. He explained further that he had swollen gum and he is currently visiting his dentist. Then I knew for sure what had happened to him. I then said he must have created room for it because he is good at taking sugary food and beverages.

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When I was a kid, I could still remember vividly what my grade one class teacher do repeatedly told us in class then. "You must brush your teeth twice daily; before going to bed and after meal in the morning". It was really strenuous to us then ;myself in particular. She used to say after taking any sugary food, we must thoroughly rinse our mouth with enough water and we should eat less of sugar. She never goes beyond that.

I used to find the warning annoying then , but later I realized that her warning actually has scientific establishment. The cause of tooth decay is plaque (a deposit stick to teeth where bacteria multiply rapidly) and an acid formed by a certain bacterium known as Streptococcus mutans using sucrose from our sugary food as it substrate.

By KDS4444 - Own work, CC BY-SA 4.0,

It might interest you to know that in just a litre of saliva there are up to one hundred million of twenty different species of oral bacteria!!!. In the space of few minutes after you have brushed your teeth, a particular substance known as glycoproteins ( protein that possess sugar covalently bond with amino acid) present in the saliva is adsorbed to the surface of the teeth you just brushed. Now the reason for that is explained here.

This glycoproteins that is adsorbed on the surface of our teeth is there to avoid

the unending deposition of salivary calcium phosphate, and to preserve the teeth from acid producing oral microorganisms after we might have consumed carbohydrates food. This glycoproteins that is adsorbed to the tooth is called acquired pellicle.

The glycoproteins of the acquired pellicle are highly sticky and several millions of oral bacteria quickly get attached to the surface of the tooth. Out of several oral bacteria that stick to the surface of the tooth, only Streptococcus mutans makes teeth to have cavities.

One question that kept on pooping up in my mind which might also be pooping up in your mind is ,why is it that it's only this bacterium that cause cavities out of several of the oral microrganisms that stick to the tooth surface?. The question is answered here in three parts.

Number one thing is that tooth enamel(that white portion of tooth) can not be dissolved as long as the pH is higher than 5.0, but Streptococcus mutans thrive at a pH range of less than 5.0 (4.5-5.0). Another point is that this microrganism has the ability to use carbohydrates to produce large amount of Lactic acid. The last distinctive property possessed by this oral microrganism is that it has a special enzyme on it known as glycosyl transferase.

Glycosyl transferase an enzyme of this microrganism has absolute specificity and use sucrose (our table sugar) as it's main substrate. This enzyme break sucrose into its two monomeric form glucose and fructose. This same enzyme add up glucose into a chain of polysaccharide known as dextran.

This polysaccharide Dextran fix itself closely to both the enamel and the bacteria. The presence of large amount of this bacteria lodged in the dextran and the dextran tightly fixed on the tooth surface give rise to the dental plaque.

Own work, Public Domain, Sucrorose

What I explained above is just the first stage of cavity formation that my student I started with first experienced. Fructose or fruit sugar a monomer obtained after sucrose has been broken down by the enzyme of the bacteria is used by the bacteria to generate energy pathway for the break down of glucose (glycolysis) and anaerobic means of lactic acid fermentation. It is this lactic acid formed that lower the pH on the surface of his tooth thereby dissolving the calcium from the tooth enamel.

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You might ask why should we still have lactic acid unremoved since we have up to a litre of saliva been produced daily?. Well the problem lies with the dextran plaque which does not permit the saliva to penetrate itself. In this way, room is given to the bacteria and it products formed through fermentation to be established on the enamel. The calcium on the enamel is then been dissolved seriously as a result of the fermentation activities going on.

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Combating tooth decay

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Should we then live with a hole on our teeth or we should just let our teeth deteriorate ?. I think that is not good enough. Let see some of what we can do to keep a healthy teeth.

Eating a diet sufficient in calcium is not a bad idea at all, as it helps to build strong tooth enamel. We can also eat diet rich with complex carbohydrates, reason been that they are not substrates for glycosyl transferase and will not lead to the formation of lactic acid which dissolves calcium on the enamel.

Taking fruits and vegetables that are rich in complex carbohydrates is also very good because these helps to avoid tooth decay through fruit and vegetable ability to mechanically remove plaque from tooth surfaces.

After taking wine or caffeinated drinks, endeavor to rinse off with enough clean water.

To those that love sucrose rich food , I think they better have a rethink if they haven't started experiencing some not so funny pain. Though Studies has shown that if one can quickly brush after taking sucrose rich food, cavity formation may be prevented.

Supply of Fluoride too can help to protect children from having dental caries. In some advance countries, fluoride is added to community water supply.
Incorporation of fluoride into enamel of tooth too can transform hydroxyapatite into fluorapatite. Fluorapatite give high resistance against dissolution by acids.

SUMMARY

The cause of tooth decay is plaque and an acid formed by a certain bacterium known as Streptococcus mutans using sucrose from our sugary food as it substrate.

A litre of saliva contain up to one hundred million of twenty different species of oral bacteria.

In the space of few minutes after brushing our teeth, a particular substance known as glycoproteins present in the saliva is adsorbed to the surface of the teeth we just brushed.

This glycoproteins on our teeth is there to avoid the unending deposition of salivary calcium phosphate, and to preserve our teeth from acid producing oral microorganisms after we might have consumed carbohydrates food.

Tooth enamel can not be dissolved if the pH is higher than 5.0, but Streptococcus mutans thrive at a pH range of less than 5.0 (4.5-5.0). Streptococcus mutans has the ability to use carbohydrates to produce large amount of Lactic acid. Streptococcus mutans has a special enzyme on it known as glycosyl transferase
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REFERENCES

Robert L. Caret, Katherine J. Denniston and Joseph J. Topping. (1993). Principle & Application of Inorganic, Organic and Biological Chemistry.Dubuque, IA: Wm.C.Brown Publishers.

Glycolysis-steps-diagram-energy-yield-and-significance

Cosmetic-dentistry/teeth-whitening/tooth-discoloration

Wikipedia.org/wiki/Dental_pellicle. Retrieved on 5th June 2018

Wikipedia.org/wiki/Glycoprotein. Retrieved on 5th June 2018

Wikipedia.org/wiki/Lactic_acid_fermentation. Retrieved on 5th June 2018