When Dr. Purva Merchant checks her email, she gets all the same ads from businesses, updates from friends, and notifications as the rest of us—with one twist. Several messages a day say things like, “If you don’t give me $100, I will scream,” “If you come in the morning you can have popsicles with us and I will hold it for you because you are small,” and “Please only use pixie and fairy dust to fly and NOT GLITTER. I’m a hockey player, don’t need glitter.”

That’s because the Seattle-based pediatric dentist doubles at the tooth fairy.

It all started in 2004, when Merchant’s then-boyfriend, now-husband, an IT guy, set up an email account that was thematically relevant as she was applying to dental schools. A few years went by without incident, until a mom she’d never heard of wrote to the email address and asked if she could please be sure to stop by today, as she’d missed Calum’s house the past two nights. Merchant decided to play along. “I’m so sorry to have missed Calum’s tooth,” she wrote. “I’ve been busy picking up teeth from all the other little children’s homes. It’s been a busy season for me. I’ll be sure to stop by tonight :)”

Since then, the trickle of emails has gradually evolved into a stream—for that reason, she’s asked that we don’t publish the specific email address and turn it into a flood—but she continues to respond to the children, parents, grandparents, and other loved ones and caregivers who write to her.

“Losing a body part is a big deal for a 6-year-old,” Merchant says. “That’s a scary thing. If we can make that…a nice thing happens when you [lose a tooth] and somebody else cares and brings you a special surprise, and create this feeling of joy around such a devastating situation, then I’m all for it.”

She publishes some of her favorite letters to her Instagram Stories. There’s everyone from the kid who lost his first tooth while eating and now worries his mom is going to have to fish it out of the toilet to the one who’s afraid to lose her last tooth because it means she has to get braces. Then there’s the parent who says not to come because Corbin was caught on his iPhone at 10:30pm, the girl who cried when she lost her tooth in a taco because she was going to use the money to buy a Father’s Day gift, and the 6-year-old who wants to make sure the tooth fairy knows that her cats, Mufasa and Pepper, do not want to eat her.

Merchant loves the variety in these messages. In fact, it was variety that drew her into pediatric dentistry in the first place. “There are nine different specialties that one can do for residency after dentistry, and in every other specialty you give up something—meaning, if I became an oral surgeon, I would never do a filling again. If I became an endodontist, or root canal specialist, I would never put braces on. If I became an orthodontist, I would never extract a tooth,” she explains. “And so every specialty felt like I was giving up things, but pediatric dentistry felt like I was doing all of it.”

Her cover was blown this past summer, when The New York Times featured her in a story. Now her teams at Seattle Kids Dentistry and Redmond Kids Dentistry know about her double life, and some of the families of her patients have given her a wink and a nod on recent visits.

The most unexpected outcome, however, has been the fan mail. The story struck a chord, particularly in older generations, and Dr. Merchant says she’s gotten mailed letters from people in their eighties and nineties. She’s even received gifts, including a tooth fairy pin and a porcelain tooth collectible. “There have been these sweet acts of kindness that somebody’s done for a stranger that really have felt very, very wholesome,” she says.

Spreading a little kindness is, after all, the whole purpose of being the tooth fairy—along with encouraging kids to brush and floss, of course. She typically signs off with, “Happy growing up!”

And she means that, whether she’s corresponding by email or seeing children in person. Now closing in on two decades as a pediatric dentist, there’s no specialty she’d rather be in. “There’s a certain type of madness, unpredictability, cuteness, curiosity that happens in a child’s life that you get to be a part of, and you get to be a part of that for 18 years,” she says. “So it’s an honor, and it’s a madhouse all at the same time.”