My wife bought new toothbrush heads on her way home from work today.
They didn’t fit. She bought the “Oral B IO” heads, but we have a “regular” Oral B toothbrush, not the Shiny Fancy IO design.
And this is after she bought replacement heads last week at another store – which turned out to be “compatible for” a different brand :(
Ugh.








No. Double blind means that both the researchers and the participants don’t know who is in which group (control group or experimental group). The idea is to avoid spoiling studies with the placebo effect.
It’s kind of hard to avoid knowing that you’re in the control group when you’re being asked to brush with an old-fashioned toothbrush instead of an electric one.