Slight bug you should fix

This is the greatest game Ive ever played in my life. There is just one slight bug. On the bottom row of their teeth, in the very back on the left side on the back tooth, there is a little black splotch on the left side of the tooth that doesnt come off no matter what. Can you please fix that so I can finally completely clean Billys teeth. Great game though. Love,
Graye

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