funny thing is that you are asking for advice for something that you dont like doing...either way, i assume you are talking about a street fight.

first things first, its pretty easy to knock a tooth out.

second, if he didnt seem phased or off balance, you probably didnt get him that hard after all, and you certainly didnt get him in the right spot. its not too hard to knock a person out with a bare fist so long as you know where to put your punch, and the teeth is certainly not that spot. drop it down an inch or so from the bottom row of teeth and then he will be down. hitting the top row of teeth doesnt do shit, i actually think thats probably the most stable or protected area on the face because of the arch structure.