my baby is 1yr 9 months old from which age I have to start brush the teeth of my baby

A. hello sir you should start brushing the teeth of your kid initially you can start using the soft finger based brush and later on you can move to normal age appropriate toothbrush for your kid and you can apply kids age appropriate floridated toothpaste but make sure the amount of toothpaste is not more than size of rice grain till the age of 3 years few examples are Colgate kids cheerio etc.