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How dirty are your dental retainers? Featured science projectScience project video


Should you brush your retainers with toothpaste? Will it suffice to rinse them with mouthwash? This science fair project aims to investigate the methods available for minimizing the amount of bacteria found on dental retainers. This experiment is carried out by comparing the amount of bacteria found on dental retainers that have been subject to infrequent brushing, regular brushing with toothpaste and soaking in mouthwash.


There will be greater amounts of bacteria  on dental retainers if they are worn  without  being regularly brushed with toothpaste.

Scientific Terms

Microorganisms, bacteria, microbes, plaque


Dental hygiene and retainers

Different types of microbes and bacteria can be found living inside the mouth cavity. These microorganisms live on remnants of leftover food in our mouth.  Bacteria  digests the starch and sugar found on the surface of our teeth and produce acids that can dissolve teeth enamel  This  causes tooth decay. Bacteria  in our mouths is  also responsible for the formation of plaque and bad breath.

Brushing our  teeth regularly with tooth paste and rinsing our  mouth with mouthwash are important measures necessary for maintaining good dental hygiene. This also  helps to remove plaque, prevent gum disease and tooth decay.

Dental retainers are used to maintain teeth positions after the removal of braces. . Dental retainers are usually worn more regularly just after the braces are removed, thereafter, they can be worn less regularly, according to the directions of the orthodontist. Dental retainers require daily cleaning just like our teeth do, in order to prevent food residue and bacteria from accumulating. .

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Complexity level:
Project cost ($):
Time required:
1 hour for preparation, 8 days for experiment
Material availability:
Access to laboratory equipment (eg. petri dishes)
Safety concerns:

Always follow laboratory safety guidelines and always practice sterile technique when handling microbes. Never have any food or drink at your workstation and always thoroughly wash your hands with disinfectant soap or alcohol before leaving your workstation. Always dispose of used material in a biohazard bag. If none are available, the bacteria should be destroyed with bleach before being disposed of