Make it fun, sing songs and try to make tooth brushing a happy time.Give her a second tooth brush to hold and use the other to brush her teeth. This can distract enough to quickly get it done. Or try a rechargeable electric toothbrush. An electric toothbrush can usually do a better job than a manual one, when you have really limited time in there to brush it properly. There is a lot of choices, but it was the counting that made the difference for us. So, try all the techniques and more and never give up.