My husband and I know that our children will, collectively, lose enough teeth to outfit a piano keyboard. Even so, our eldest daughter’s first lost tooth is no small milestone. We cheered as Laura ran to the mirror to inspect the new hole in her mouth. Then she carefully slipped the tooth into a plastic baggie for the tooth fairy.

At bedtime, the meaning of the lost tooth became clear. It launched our debut as the tooth fairy. Precedents would be established, traditions launched, and monetary values set.

“Who’s going to do it?” I ask.

“I’ll go. How much are teeth worth?”

“I don’t know, should I call my mother?”

After rummaging through his change box, Mr. Tooth Fairy decides on a quarter and heads for the stairs. Several minutes later my level-headed husband returns with the tooth, and a sappy smile on his face. I stand in the kitchen, ready to pop the tooth into the trash can. Mr. Tooth Fairy cradles the tooth in his hand and we gaze at it through the baggie.

“Should we keep it?” he asks.

“No. Who keeps a tooth?”

“It’s so small,” he says quietly.

“It’s one of the first things we knew about her.”

“Yeah.”

It’s true. We had known about this tooth five years ago, before we met our daughter. Its existence was noted in the medical report sent from an orphanage 5,000 miles away to our adoption agency in Virginia. After waiting for what felt like an eternity, we got the call to pick up the referral documents.

When I opened the large white envelope, I saw an adorable baby, her tongue impishly stuck out one side of her mouth. She lived oceans away and had a name I couldn’t pronounce, but she was my daughter. And there in the photo was the tooth we had read about! I drove home with one hand on the wheel, hugging the papers to my body as if they were my baby.

We started protecting this tooth the day we met our daughter in a hotel room. It wasn’t an easy task. Laura was 14 months old, newly separated from the only people she had ever known, and didn’t understand what the Winnie the Pooh toothbrush was for. We decided we’d wait until we got home before declaring brushing mandatory.

Wasn’t that only yesterday? How is it possible that we’re now holding her tooth, separate from her mouth, in front of us?

The tooth reminds me that everything about her life before she joined our family remains a mystery to us, though I’ve wondered and imagined so much about that period. This tooth in my husband’s hand is as solid a clue as we’ll ever have about her first 14 months of life.

My baby book tells me that children start cutting teeth in their first six to 12 months of life. The timing is hereditary. Her birth parents must have cut and then lost their first teeth at around the same ages that she did. Tonight, we’ve found a new link to them. Someday, Laura will own the journals I’ve been keeping so carefully and read about the night when her first tooth fell out. I wonder if it will hold as much meaning for her as it does for her dad and me.

We stand there a few minutes longer, huddling over the tooth, contemplating our history with it. Finally I say, “You don’t have to throw it away.”

“Oh, good,” he whispers, and slips the bag with the tooth into his pocket. Maybe our daughter will inherit Mr. Tooth Fairy’s sentimentality.