I tried it. My right brain is very, very bad at tooth-brushing.
Interestingly, my right hand apparently really wanted to help. Mid-brushing I noticed that it was clenched into a fist and was raised about halfway to my head. Scary.
(The point, in case you haven’t memorized everything I’ve posted this year, is that doing new stuff – or old stuff in new ways – is alleged to forge new synaptic connections, making you smarter.)