My son hates brushing teeth too, it’s a real struggle. But recently we tried no flavour toothpaste and I think he prefers that cause he actually open his mouth and let me brush (but still whining) I started with silicon so it’s not too harsh cause I keep thinking maybe the bristles are painful. Slowly I change to a toothbrush that he likes (giraffe shape) and somehow it’s better now
hope this can help https://sg.theasianparent.com/kids-hate-brushing-teeth