“Hmm,” Dr G said to me while he carefully picked into my periodontal pockets. “I don’t think you want to start in on all the cosmetic stuff, but have you considered a night guard?”

I started seeing Dr G 15 years ago, after my dentist surprised me with the announcement that I had periodontal disease. “Severe,” he said. “Advanced.” In the ensuing decade and a half I’d been through every normal procedure: deep root cleaning; scaling; retuck surgery; gum grafts; bone grafts; extractions; implants. I’m now in remission, kind of; it appears that I won’t have to go for more extractions and implants for the foreseeable future, as long as I continue to take the $1 pills twice a day and engage in elaborate deep flossing rituals. “You only have to take care of the teeth you want to keep,” Dr G says.

I see a new dentist now (the last one retired). He and Dr G mention the night guard whenever they examine my teeth. I resist. Not only do I not want to add another impediment to sleep which is coming harder every year, but I maintain that I’m not grinding at night. Oh I used to gnash. I learned that 25 years ago, when I’d wake with headaches that seemed to come from my jaw. I went for physical therapy then about my neck; I was educated about relaxing that area. I stopped letting my teeth clamp when I slept. I may clench my jaw, but when I tongue-check the ivories there’s always a space between my uppers and lowers.

“I don’t need a night guard,” I told Dr G. “I know there’s evidence of grinding, but that’s old evidence. I don’t do that any more.”

“Hmm,” he said.

Then he pulled out his steel hand mirror, a device one’s breath can’t fog. He had me hold it where I could see my own mouth, and then he made me adjust my teeth together so they fit. Oh my. I had to move my lower forward and my upper back. And gnash the uppers a bit to my left. Oh my.

I took myself, mouth and mirror impressions and all, home. I settled into my normal evening routine. Within a few minutes I was on my little couch, in front of the TV but browsing on my iPad, when I began to engage in my oldest nervous activity: nibbling on my fingertips near my nails.

I was a nail-biter when I was a kid. I dropped that habit at around 12, but I took up fingertip and cuticle nibbling. Especially on my thumbs and index fingers. It’s disgusting, I know, especially when my hands get wet and show the fingertip raggedyness, but it’s not my bad habit alone. Watching people as I do, especially on public transit, I see many digital nibblers.

As I began to chew that night: wham! I was struck with somatic memory. I had just put my teeth in precisely the position I’d earlier seen in the dental mirror.

Uh huh. When one bites one’s nails or fingertips, when one chews on a pencil or a paper clip or a piece of plastic, one uses the front teeth! We cut with them but we also chew the item with them. Really. No one uses molars for this.

Yet no dentist has ever asked me if I chew my fingers or bite my nails. No dental professional has even looked at my hands.

Dr G is right. My tooth wear isn’t just historical; it’s ongoing.

And I’m right. I’m not doing damage while I sleep.

I need a day guard.