There is something about a toothless grin. Not the gummy smile of infancy, but the wide-gapped delight of a child who has newly lost a tooth. Today’s was not the first tooth my son has lost—the first was over a year ago—but today, the fifth tooth, was a top one, and today his smile seemed to announce with an oh, so in my face clarity, that he and I had better make room for adulthood (or at least, pre-tweendom?).

He is shedding his babyhood. Those teeth that kept me up at night on their way in have outgrown their use. And I’m not sentimental about babyhood—I couldn’t wait to be done with my slobbery, teething babies. I fretted over each imminent tooth only in part because they kept me up at night. Mostly, I just wanted my babies’ childhood—the give and take of emotional parenting, rather than physical parenting—to begin. But now, with each tooth lost, I feel as though I too, am outgrowing my use.

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The small child, the one I could carry, the one who thought I was just the silliest, wisest woman ever, the one who trusted all I had to say . . . that one is no more. Now he rolls his eyes at me (at me!). He tells me I couldn’t possibly understand. He’d rather just read by himself, thank you. And yet, he’s not quite sure whether I am, in fact, the tooth fairy. He likes a good snuggle before bedtime. And some books are a lot more palatable if a grown-up is reading out loud.

A writer friend of mine, older and with grown kids of her own, wrote me a note when my son was born. “Motherhood,” she said, “is a series of lettings go.” It’s true, of course, but in that gappy mouth, it becomes clear that the letting go is tooth by tooth: babyhood, next to empty space, alongside budding adulthood. I see that the window between two stages is tiny, if at all, and that children (or even adults) never quite find themselves firmly planted in one phase. There will always be a piece of what came before moving forward with us.

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I am transfixed by this new smile and already missing the old one. I am excited for all the things I can share with a big kid even as I miss all I shared with my little one. In short: I’m letting go, but I’m holding on to the teeth.

Originally published in New York Family Magazine.