I'm so glad it worked, that's really good.
I just thought I'd share some of things that have worked for us too, in case anyone else has the same problem.
With us, my son is now 7 and has ASD . Brushing his teeth is one of the more persistent challenges we have.
Quite often sometimes things work for a while then they don't and you feel you are back to square one, but over the years we have had most success with cleaning his teeth in the bath, and singing a song to go with it....
I started off with Brush Brush Bree, from Bear in the Big Blue House , which he loved at the time, and this worked for a while but not very well.
The big breakthrough came with Shrek, as Shrek cleans his teeth in the opening titles, and my son would copy him. So I got a plastic Shrek toy, and had him brush the toy Shrek's teeth while I brushed his. Then he started singing the song that went with it; All Star by Smash Mouth. So I had to learn that and sing it while I brushed his teeth. He would allow me to brush while I sang, for the entire length of the song!
Now Shrek has gone out of fashion too, and currently I have to sing "I'm a pink toothbrush"....but we now have him using an electric toothbrush, which is great. His SN dentist says just to do the best job we can and try and keep his sugar intake down. So far no problems.....
Good luck!