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 a day, helps us keep these microbes at bay. It also gives us many life-changing health benefits.
Child: Really?
Mom: Yes! Do you know how my grandfather used to brush his teeth?
(Child shakes her head to say no)
Mom: He used to make a toothbrush from the twig of a neem tree! He would chew its ends, make bristles and clean his teeth with them. He had really strong teeth. In a lot of villages, people continue to use neem twigs from their backyard for oral care. See, this is what a neem brush looks like.
Child: Wow! But why aren’t we using this kind of brush?
Mom: Due to our modernized, busy lifestyles and eating habits. As a result, periodontal or dental diseases became much more prevalent. Child: Mom, sometimes my teeth feel sticky. Is stickiness also a dental disease?
Mom: The sticky substance is plaque, commonly known as dental plaque. It’s not a disease, and it’s harmless. It is noticeable when you don’t brush properly. If neglected, it builds up on your teeth and leads to gingivitis, dental caries or cavities, and many other periodontal diseases.
Let me explain:
(Mom, who is doing her postdoctoral work on the enzymatic treatment of dental plaques,
Dr Sirisha Boddapati || 51
starts to explain the cause of dental plaque.)
Dental plaque is a sticky, colourless bacterial biofilm, which builds up upon the tooth enamel and between teeth, and hides under the gums. It consists of proliferating microorganisms (50%–70%), glycoproteins and mucopolysaccharides (glucans and fructans). One of the main culprits for the dental plaque is Streptococcus mutans, a gram- positive bacterium. Human teeth are its world. It lives in the nooks of the teeth, feeding on leftover sugars from our food. From the mother, the bacteria silently enter the child’s teeth,
inhabit and remain there for the rest of its life. Child: Really? Wow!
Mom: Although S. mutans was discovered in the 1890s, the organism’s first description and name were given by J. Kilian Clarke in 1924. Four genes gtfA, gtfB, gtfC, and gtfD secrete cell wall-bound glucosyltransferase SI (GTF SI) and glucosyltransferase S enzymes (GTF-S). These enzymes break the sucrose present in sugars into glucose and fructose and join glucose molecules to form water soluble and insoluble glucans with alpha 1-3 and alpha 1-6 linkages. These sticky glucans help the bacteria firmly sit on the teeth enamel, form bonds with other bacteria present in the mouth cavity and aid the overall development of the complex biofilm. Since these bacteria eat leftover sugars, they release lactic acid, resulting in acidic pH as low as pH 3.0 inside our mouth cavity.
Child: The pH as low as 3.0! But Mom, can S. mutans itself survive in such low pH?
Mom: The bacteria has developed its own defence mechanism. It has evolved as an acid-tolerant bacterium and adapted to
   Dental plaque is a sticky, colourless bacterial biofilm, which builds up upon the tooth enamel and between teeth, and hides under
the gums. It consists of proliferating microorganisms (50%–70%), glycoproteins and mucopolysaccharides (glucans and fructans). One of the main culprits for the dental plaque is Streptococcus mutans, a gram- positive bacterium.
   















































































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