Hi..you might need teeth cleaning followed by teeth whitening. Regards

Hello Please go to the dentist and get check up so that you come to know about the main reason for them

you can go for professional cleaning ie scaling

We have t see clically ..what types of stains r dere...some may be removed by scaling only...others require bleaching or laminates...plz consult ur nearby dentist fr d procedure...cost ...duration etc etc

The description is quite insufficient to arrive at a rational diagnosis of your problem. It will be great if you can post a clinical picture for us to provide a more streamlined opinion. Roughly speaking, if these yellow lines are extrinsic they can be removed by teeth cleaning through procedure called as scaling. But if these are intrinsic stains they will require aesthetic treatments like bleaching or laminates as a camouflage approach to conceal them and beautify your smile. Please consult a dentist for a proper clinical examination so that the right treatment options applicable for you can be explained to you. Regards. Regards.