Hello, This could be due to deposits on your teeth . Visit a nearby dentist and get scaling done. You will not be able to remove the hard deposits on your own.so get professor assistance. Regards

Hello, As per my understanding with the yellow substance you mentioned it's hard deposits that has been accumulated over years, it can be detrimental for your teeth. So kindly contact your dentist for an oral prophylaxis visit . Only professionals can help u get rid of this , not brushing. Thanks

Get the professional scaling procedure done from ur dentist

Hello, Visit a nearby dentist. Scaling and Polishing followed by teeth bleaching ( if required) will be good.

Need to visit dentist.If it is a layer formed on ur teeth scaling will do or need to do bleaching.

Yellow deposits on tooth is the plaque sheet which develops on the tooth surface every 4 hours. Using a good toothpaste and proper brushing technique may relieve this problem for few hours. But visit a dentist nearby so that he can asssess whether these deposits can be cleared by scaling and polishing and then you maintain it by proper brushing and cleaning techniques

This will not go by brushing alone as the deposits are already hardened . So go for scaling and polishing .