Spoiler alert: Not intended for those under the age of 10 or inclined to believe in benevolent, magical intruders.

I'm exhausted. My son lost a tooth last night.

Actually, it was hardly a tooth at all. His baby teeth tend to linger until they are empty shells, worn away by the emergent new tooth. His older sister let me pull her wiggly canines and loose bicuspids. She wriggled and worked her dangling incisors, anxious to invite the tooth fairy. I didn't realize that not a single one of her teeth fell out naturally until she ate only yogurt and soup for a long weekend in an attempt to preserve her last baby tooth so that it could drop at school, where, she would receive an adorable plastic hinged tooth box from the school nurse. My son (wisely) won't let my fingers near his mouth.

His fear of my home-dentistry tendencies have led him to not announce when a tooth is loose until it actually falls out. (I should mention that I also pulled my dog's baby tooth when it shared a space with her adult canine.) His tight-lipped policy can cause tooth-fairy planning problems.

More than once, I (while trying to fulfill my role as tooth fairy) have been caught without any cash, or with only inappropriately large bills. It was thus necessary to institute a policy in our household whereby the tooth fairy schedules her nocturnal runs at six p.m., and, if a child loses a tooth after the cut-off, is deferred to the following night's schedule.

We have (on a couple of occasions) had to leave an I.O.U note for the fairy for a tooth that has been irrevocably lost in the pockets of blue jeans or down the bathroom sink. I once chose to respond (in pink fairy ink and best curly penmanship) to a polite thank-you note written by my daughter addressed to the tooth fairy after receiving $1.75 in shiny state quarters.

I've also slept through the night, leaving the dollar bills folded on my nightstand until the early-hours of the morning. "She forgot me!" I have been awakened by one of my beloved children holding the old tooth above my head in the barely-morning light. As a parent, this is a new low and requires some quick thinking as well as slight of hand.

"Maybe she just dropped the tooth," I say. Let's go check. Luckily, we're all still sleepy at this point. I palm the cash and try to pretend that I found it under the far corner of the pillow. Once, desperate, I had to drop it on the ground as if it slipped out. "Must have been an intern or something." It would make sense to exchange the tooth for the money late at night, before I go to bed and after the children do. But, you see, I was once caught at playing Easter Bunny. And after that happens, you're wary. Childhood is fleeting, but that's not the problem. Parenting-guilt endures.

Last night, I only had a ten. The going rate for lost teeth seems to be about two bucks. But, he's 10 years old and has only has a couple of tenacious molars remaining. Ten's old enough that the fairy doesn't get credit anymore. Ten is also old enough that he doesn't want to wake up to a handful of change under his pillow.

"Thanks, Mom," he said this morning, before my alarm clock sounded, waving a $10 bill at me.

I think my fairy days are over.

Krista Richards Mann is a Westport writer, and her "Well Intended" column appears every other Friday. She can be reached at: kristarichardsmann@gmail.com.