Is sharing a toothbrush with your partner ok?
ABC Life recently enlisted the help of oral biology expert, Dr Samantha Byrne from the Melbourne Dental School, to weigh in on whether or not you should share your toothbrush with your partner or skip a night of brushing.
Why it matters
There are over 700 different bacterial species that can call the mouth home, but one person is more likely to have about 200 bacterial species living in their mouth, along with some fungi and viruses, said Dr Byrne.
But it's not all bad news. Many of them are good for us.
"Most of these are not harmful and in fact are probably beneficial in some way."
The bacteria commonly found in the mouth that can be harmful, however, include Streptococcus mutans (often associated with tooth decay) and Porphyromonas gingivalis and Treponema denticola (associated with gum disease).
Dr Byrne says those diseases are largely preventable with good oral hygiene and diet.
What bacteria are on my toothbrush?
The three species of bacteria mentioned also have been found to live on toothbrushes.
Allowing your toothbrush to dry between uses will ensure most bacteria transferred from your mouth die, said Dr Byrne.
"The microorganisms that are from your mouth, they are not really evolved to live on a toothbrush."
The more problematic bacteria are those that most likely come from the nasal passages, skin, hands and the bathroom itself, as from a flushing toilet. These include Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli.
Does all this mean sharing a toothbrush is riskier than kissing?
Probably not, according to Dr Byrne.
"The reality is if you are kissing somebody, sharing their toothbrush is probably not a huge leap to make," she said.
"If you live with someone, you are probably swapping those microorganisms anyway."