‘Please, could you just clean my teeth?’ I want to say, only I don’t. I go along with it, praying it will be over quicker if I cooperate.

‘And how are you today?’ she says in a frighteningly polite voice, a flash of steel glinting in her eyes as she looks down on me in her impossibly white outfit.

‘Well, I’m at the dentist so…’ I give a little nervous laugh, inviting her to show me she is human. She refuses. Her expression flickers for a second, then she hardens the courtesy in her tone.

The angel of hygiene is now being ultra-polite, a tone that meets menace coming round the other way: ‘Is there something wrong? Is there anything I can do?’

I can see that we are into ‘Do you need to take a moment?’ territory. This can only draw out the misery.

‘I’m fine. I just need to…’ Get it over with! Get your screaming electric scraper going and discover how bad my gums are and then give me the goddam lecture about flossing!

I know this lecture is coming, as surely as I know anything. ‘It’s nothing,’ I say. ‘I’m just stressed.’ With soul-crushing correctness, she says: ‘I’m sorry you feel this way. Have you had a bad experience in the past?’

Fine, I think, I’ll let you have it. ‘The thing is, the hygienist I was seeing before, at the other practice, she used to lecture me about flossing every time I went and I came to dread it. I know I should floss. But I have this thing. It gives me the heebie-jeebies…like a phobia…’

That’s it — phobia. Why didn’t I think of that before? They’ll have to back off if I say phobia. She looks deeply sorrowful, and stares down at me as I cower in her chair. ‘I would never do that to you,’ she says, and for a second I allow myself to believe her. I cheer up slightly. ‘Really?’ ‘Absolutely,’ she says. ‘I want you to feel comfortable and…’

I can’t remember exactly what comes next because she went off into all kinds of ‘safe space’ guff.

She could have run one of those courses at universities where they train students to address each other by their pronouns of choice.

I try to feel reassured, though a nagging doubt persists that her lecture about not lecturing me about flossing cannot be the whole truth.

I settle down and take the protective glasses from her to put on my face and she begins.

There is a lot of squealing and water squirting from the ultrasonic scaler and she pauses a few times to check I am still in my safe space and I say that I am, when of course I am not. I am in hell. I am Dustin Hoffman in Marathon Man.

Obliquely, it occurs to me that Laurence Olivier repeatedly asks Hoffman ‘Is it safe?’ as he is torturing him with dental tools.

Mercifully, she is polishing me up before too long and as the session has been quite short, I wonder if my gums weren’t so shocking after all. Perhaps the three flossing sessions I have performed in the past 12 months have sufficed and I have pulled it off for the first time ever.

After all, I do brush my teeth morning and night. And I have just been seen by the dentist, who has confirmed there is no sign of decay. I have a lovely set of gnashers for my age. I must be doing something right.

‘Big rinse,’ says the hygienist, in a tone that is inscrutable. I grapple with the plastic cup, wipe my mouth, and sit back in the chair.

She is sitting behind me on her chair and as I swivel round to look into her steely eyes, she begins.

‘So, do you understand how to brush your teeth?’

Somewhere, an orchestra strikes the first chilling chord from an original soundtrack by Michael Small. Screeching violins give way to sparse, melancholic piano. I grip the sides of the seat. This can’t be happening.

‘I am going to show you how to do it.’ And she begins a 20-minute lecture on how to brush, going through it tooth by tooth, placing the brush on each tooth, then making me place the brush on each tooth. It feels as though there are about 56 of them but this cannot be right.

And when she has given instruction on the placing of the brush on each tooth, she starts on the flossing. A low piano chord thunders.

‘You promised me,’ I think. ‘You made me a promise.’ ‘Are you alright?’ she says, irritably.

I am torn between saying: ‘I’m out of my safe space,’ and ‘Why can’t you people ever just clean my teeth?’