Hello. Permanent teeth are generally slightly yellowish in color as compared to milk teeth. If that is the case then there’s no problem. But there can be other reasons also for yellowish discolouration of the teeth. It can be due to stains/ hard deposits on the tooth surface which needs professional tooth cleaning or dental fluorosis.

Depends on fluorosis or improper  brushing

It may be due to improper brushing

Color of the teeth depends on various factors,example:- Dental fluorosis,improper brushing,age related,using of certain medicines,so visit nearest Dr .

Hello! Kindly attach pic for better suggestions

Improper brushing, intake of beverages.

Hi, Share picture.