When dentists refer to seals they mean fillings. That is, the replacement of the morphology of the tooth which has been altered mainly through decay. The materials with which dentists seal a tooth (cavity) may be amalgam, resin or porcelain. The fillings can be direct (that is the tooth is properly prepared by the dentist who will fill the tooth that has been lost with resin, amalgam etc. ) or indirect (that is the part of the tooth that has been altered will be constructed in a dental laboratory and on a second visit, the dentist will complete the filling).
Note: Our dental surgery does not use materials containing mercury (eg black-amalgam fillings). Some people may be allergic to mercury or be concerned about the consequences. Studies have shown that the amount of exposure to mercury from fillings is similar to any other source people are receiving from the environment. Yet the FDA (USA Food and Drug Administration) and the ADA (American Dental Association) are considering abolishing the use, whilst some countries have already banned its use.