when my oldest was 3 she had 6 cavitys in her teeth, mostly from falling asleep with her bottle, we took her to dr balta in washington who put her to sleep to get those cavitys fixed. they take her height, weight, bllod pressure, and give her a small shot, then out she goes, and 10 min later she was done, they gave her another shot to wake her up, she was groggy, and slept off and on most of the day. she acted pretty doped up, but it saved her permament teeth from coming in to early, remember we only get 2 sets of teeth, yry to keep the first set as long as possible.
i couldnet imagine getting it done any other way. they are just to little to sit still, they would freak out at the novacane shot, the noise from the drill would drive them nuts, and the whole trip would turn into a barging session with a 4 year old, and you wont win. the dentist knows what they are doing, and your 4 year old wont remember a thing, and will be able to not have to loose teeth any sooner than thet have to.