Normal tooth color varies from person to person, it can be light yellow to grayish white. The enamel or the outer covering of the tooth is slightly transparent and the yellowish color of the underlying dentine is shown through it. So permanent teeth will appear slightly yellowish. In your case you haven't mention the duration since you have had discolored teeth. But thorough clinical evaluation by a dentist would help .

yellowish teeth may be due to many reasons such as tea /coffee stains, fluorosis stains, tobacco / pan/ pan masala stains, due to any trauma or any adverse drug reaction etc.  Visit a dentist for proper evaluation and treatment planning. Firstly oral prophylaxis or scaling of teeth is advised. For more whiteness you can opt for bleaching treatment.  Thanks

Hello it may be due to plaques consult dentist for further evaluation and treatment.