# Tarnish generally occurs in the oral cavity due to:
A. Formation of hard and soft deposits
B. Pigment producing bacteria
C. Formation of their oxides, sulphides or chlorides
D. All of the above
The correct answer is D. All of the above.
Tarnish: It is the surface discoloration or alteration of the surface finish or luster. It generally occurs due to formation calculus, plaque on the surface of the metal. It also occurs due to formation of oxides, sulfides or chlorides. Tarnish is the forerunner of corrosion.
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