fear factor parenting

it started out innocently enough, I told my son if he didn't brush his teeth after every meal his teeth would fall out. Now he brushes them when he is done his morning milk and when he goes to sleep at night.He is very consciences about it too- if he has a snack after his teeth are brushed he will brush them again before going to sleep for the night. I am proud of this. I think that warning him about the ill affects of his actions is a good way to get him to understand how important it is to brush his teeth (or to eat his vegetables, drink his milk etc...) Some may not agree with this style of parenting. Recently we were criticized for using fear (warnings!!) to get him to listen... we really didn't know a better way- any suggestions?!?!