I don't know if I'm being stupid or not. My child's toothpaste says it's contains Sodium Fluoride 0.135% (1450 ppm fluoride). That's the same as my adult toothpaste. So does that mean a child can use the adult toothpaste (obviously won't as it's stronger). I have a 3-5 year old toothpaste and a 6-9 one and they're both the same. So can an older child use the younger child toothpaste if they prefer the taste?