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Five facts you didn’t know about the dirt in your toothbrush

 Toothbrushes are an essential part of our daily personal care routine. Whilst we use them to clean our teeth, we also have to remember that they can also become contaminated after exposure to germs found in our bathrooms, and the bacteria they’re cleaning from our mouths.


Our toothbrushes are contaminated every time we use them, meaning they accumulate microorganisms that could cause and lead to disease.

Ever wondered just how dirty your toothbrush is, and how many times a year it should be replaced?

Doop has analysed medical studies and consulted experts to get some interesting data about the presence of bacteria on our toothbrushes and how they contribute to the transmission of diseases.

1. There are 10 million bacteria on every single toothbrush

A recent study by the University of Manchester showed that toothbrushes can accumulate more than 10 million bacteria, which is more than the bacteria found in a toilet seat (50 per square inch) or in a public lavatory floor (2 million per square inch).

“The bacteria that are already in our mouths will certainly be the most common bacteria found on our toothbrushes. This bacteria can certainly continue to multiply on our toothbrushes if there are food particles also present”, adds pediatric dentist Laura Huling.

These results were also supported by research in 2011 that found Streptococcus mutans, Staphylococcus aureus, Pseudomonas, Lactobacillus, Klebsiella, Candida species and E. coli in used toothbrushes kept in toilets. These are responsible for causing tooth decay, pneumonia, skin and fungal infections, stomach cramps and diarrhea, among other diseases.

2. The more you use your toothbrush, the dirtier it will be

The contamination of your toothbrush starts from the first use and increases over time. For this reason, it’s really important to regularly replace the toothbrush or the part that is inserted into the mouth - its head. Research from 2007 found that 70% of toothbrushes can become heavily contaminated with pathogenic microorganisms after use.

“Bacteria will naturally build up on your toothbrush over time. Some are picked up during the brushing process, while others come from the environment where your toothbrush is stored”, says Brian Maurer, co-founder of the oral microbiome testing company Bristle.

3. The way you store your toothbrush can increase bacteria and germs

Bacteria survival is affected by the way toothbrushes are stored. Research also found that the use of a cap for toothbrush storage is actually increasing bacteria’s survival.

"Many people use toothbrush covers, believing that it will help keep the bristles bacteria-free. However, the opposite can be true. Bacteria thrive in moist conditions so covering a wet toothbrush head can actually encourage bacteria growth. If you find it more hygienic to use a toothbrush cover, allow the bristles to dry completely before applying it", says Amanda Napitu, Chief Operating Officer at Dentaly.

4. Moisture and organic matter can promote bacterial growth

Same as the use of caps, leaving the toothbrush in wet environments and close to the toilet seat can actually increase the chance of developing bacteria and mould.

“I would recommend having at least a 5-foot distance between your toilet and your toothbrush. It is also always a good idea to close the toilet seat when you flush to prevent this splatter”, says Laura Huling.

5. Design features can affect the number of accumulated bacteria

Toothbrush design and bristles arrangement can be factors to keep in mind since most bacteria are extremely adherent to bristles.

A study from 2008 found that bacteria can be easily trapped inside the bristles if they are too close together. This research also found that microorganisms can quickly colonise toothbrushes.

When picking a toothbrush, it’s important to choose the one with soft bristles to avoid problems in the future. “Harsh brushing damages the enamel and gum tissue. Always choose the toothbrush with soft bristles and be gentle with your oral care”, recommends dentist Henry Hackney, director of Content at Authority Dental.

How to avoid contamination

Doop has spoken to experts in order to reveal the best ways we can keep our toothbrushes clean. Here are six tips to preserve your oral health:

1. Rinse your mouth with mouthwash before brushing your teeth

This simple action can contribute to reducing the number of bacteria that is transferred from your mouth to your toothbrush, due to the concentration of alcohol in the mouthwash being enough to kill some forms of bacteria and germs. It’s important to do this before, and not after, brushing.

Some experts suggest that using mouthwash after brushing may negatively impact your oral hygiene due to it washing away the fluoride in the toothpaste which strengthens our teeth.

“Rinsing after you brush, whether with water or mouthwash, could actually do more harm than good. If you use fluoride toothpaste for cavity protection, the advice from the Oral Health Foundation is ‘Spit, don't rinse’. This allows the fluoride to stay on your enamel for longer and give greater protection”, adds Amanda Napitu.

2. Leave your toothbrush soaking in mouthwash after brushing

It will clean the bristles and kill most of the bacteria and germs. Actually, a study found that rinsing toothbrushes with tap water is not enough to clean the toothbrush and it can actually result in continued high levels of contamination and biofilm.

One of the few benefits of alcohol-based mouthwashes is that it can help kill bacteria on your toothbrush. You can dip the head of the toothbrush in the alcohol-based mouthrinse, leave it for a minute and then stand the toothbrush upright to allow it to dry. I usually recommend cleaning the handle with soap and water and then leaving it upright to dry”, says Laura Huling.

3. Keep your toothbrush far away from your toilet seat

If the toilet is very close to the sink there are more chances that bacteria that is released into the air when you flush will reach and contaminate your toothbrush.

“When you flush the toilet, it emits an aerosol spray known as a ‘toilet plume’. This can travel up to 15 feet, and in the average-sized bathroom, it's likely you store your toothbrush within this range. The simple way to protect against bacteria from the toilet reaching your toothbrush is to close the lid before you flush”, says Amanda Napitu.

4. Avoid toothbrush holders and caps

Bacteria that is spread by toilet-flushing can also be picked up by toothbrush holders. A study conducted by the National Sanitation Foundation in the USA found that toothbrushes are third in the list of the most germ-filled household items, only after dish sponges and kitchen sinks.

Popular toothbrush caps can also foster an environment that promotes moisture and bacteria and mould growth. One way to prevent contamination is to store the toothbrush in a sterile place, far from bacteria exposure.

Doop was created taking special care of product materials and storage methods to avoid any possible bacterial contamination from the outside and keep customers protected. The toothbrush comes with reusable antibacterial packaging with a zip closure that turns it into a pouch to store the toothbrush far from germs, bacteria and humidity.

Moreover, following recommendations from the Center for Disease Control and Prevention and the Oral Health Foundation, Doop is made of non-porous materials and it uses DuPont Tynex bristles, made from nylon, to avoid mould and bacterial contamination and to allow proper cleaning. This information can be found on the company’s Life Cycle Assessment report that compares the environmental impacts of the Doop toothbrush versus traditional plastic toothbrushes.

5. Ensure you use your own toothbrush

Since most of the bacteria that accumulate in our toothbrush comes from our own mouth, it’s important not to use anyone else's toothbrush or let someone else use yours. Also, if you live with other people, keep everyone’s toothbrushes separate to avoid them touching.

“Oral bacteria, including those that cause gum disease, can be spread from one person to another when we kiss, share utensils, or any other possible activity that can transfer saliva. So, to avoid passing germs from one person to another, we should not share our toothbrushes”, says Brian Maurer.


6. Replace your toothbrush heads every three months

Frayed bristles are ineffective at removing plaque and food debris, meaning they could be having a negative impact on your oral hygiene. “Over time your toothbrush's bristles will wear down from use, which will affect how well you brush your teeth”, shares Brian Maurer.

A recent study discovered that bacteria levels are relatively stagnant between 2 and 12 weeks, but show an increase in number after 12 weeks, which is why it’s important to replace your toothbrush every three months.

You can opt for more eco-friendly alternatives like Doop, a recycled and recyclable toothbrush made of just one permanent handle and small removable heads that are replaced every 3 months, generating less waste than changing the whole toothbrush.

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