Spots or blotches of different shades or colours(noun)
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Use "mottling" in a sentence
"The first hint that fluoride might be an effective bulwark against tooth decay came in the beginning of the twentieth century, when a dentist in Colorado noticed some of his patients had small areas of discoloration on their teeth, a condition known as mottling."
"Over the course of more than a decade, he connected mottling to the naturally occurring presence of fluoride in drinking water."
"He also noticed that while large quantities of fluoride produced severe mottling, smaller quantities appeared to result in stronger teeth and fewer cavities."