When I went to a friend's house the other day, her daughter (7) was getting ready for bed, so we were all chatting in the bathroom while she was cleaning her teeth. I was
to see her pick up a toothbrush head from a glass containing three others (one for each parent and her brother), and attached it to the single electric toothbrush in the bathroom! Her mum explained that they thought buying a toothbrush each was too expensive (they are both in good jobs and not particularly tight for cash) and that it was easier to share. Apparently each toothbrush head has a little coloured ring thingy to tell them apart...???!