N J Wills-Wood’s scientific contributions

... Drugs containing metallic compounds can lead to extrinsic staining of teeth. Addy et al. (1985) reported that certain metals (especially iron and tin) can cause tooth discoloration. For example, dark brown to black discoloration was observed in people taking iron supplements, and oral iron salts in liquid form could cause the teeth to appear greenish black (Teoh et al., 2019). ...

Reference:

Drug-induced tooth discoloration: An analysis of the US food and drug administration adverse event reporting system