From Bleak House:
"The little woman herself is not the least item in his difficulty. To know that he is always keeping a secret from her; that he has, under all circumstances, to conceal and hold fast a tender double-tooth, which her sharpness is ever ready to twist out of his head; gives Mr Snagsby, in her dentistical presence, much of the air of a dog who has a reservation from his master, and will look anywhere rather than meet his eye."