A white chalky area is noted on the mid-facial surface of the canine. What is this lesion?

A focal chalky-white area on a single tooth is a hypocalcified (demineralized) white-spot lesion — the earliest sign of caries or plaque-induced demineralization. Amelogenesis imperfecta is generalized and affects all teeth. Hypercalcification is not a standard clinical term for this appearance.