What Is The Protective Coating Called That Dentists Put Over Teeth?

What is the name of the protective coating used after the treatment to prevent staining? My previous dentist put on a protective, plastic like "laminate" over my teeth upon completion which prevented my teeth from staining and polished it off 2-3 weeks afterwards. This was very effective in preventing stains and I need to know what it is because my dentist moved away and I can't find her and my new dentist does not know what it is. Thx in advance.