El-Samarrai S. Extrinsic black dental stains in relation to dental caries and mutans streptococci in saliva. MDJ [Internet]. 2004 Dec. 15 [cited 2024 Jul. 22];1(2):148-52. Available from: https://mdj.uomustansiriyah.edu.iq/index.php/mdj/article/view/1111