We just went through this with my 4 year old daughter. I took her to 3 different pediatric dentists this time around because she had cavities filled when she was 2 and it was a disaster. She had the kiddie cocktail the first time, and it made her combative. They papoosed her, and she freaked out. I regret it to this day. She didn't forget anything-still talks about it: "remember when I went to the dentist and I couldn't get away?" I finally felt comfortable with the last dentist we consulted with. She told me that it isn't unusual for kids who are strong-willed to have an adverse reaction to the narcotic part of the kiddie cocktail. Instead, they gave her a medication equivalent to a strong dose of Benadryl. After she relaxed a bit, they took her back and gave her the nitrous. I was there the whole time, outside the room, but able to observe. There were a few tears toward the end, but I think all-in-all my daughter did exceptionally well considering her first experience. Our dentist told me from the beginning that if Ellie protested too much, they would stop the procedure, and we'd try again another time. I would extract that same promise from your dentist. If your son does well now, you may not have to worry about the aforementioned information, but it should give you pause to know that all children do not respond to the kiddie cocktail in the same way. I'd find out exactly what they are going to give him and ask about the narcotic part of the cocktail, then go with your gut. Don't let them restrain him, whatever you do. It was terrible, and it's definitely had long term consequences for my daughter. You can always go back another day if you have to.