What do the "false teeth" symbolize in the novel?

In George Orwell's Coming Up For Air, the false teeth symbolize the loss of masculine virility and the deeper loss of much of England's fertile landscape in the face of 'Progress' or industrialization. The false teeth also encapsulates the loss of individuality in the face of relentless change; additionally, it highlights the inevitability of a relentless war which the protagonist fears will destroy a once virile civilization.

It struck me that perhaps a lot of the people you see walking about are dead...They think that England will never change and that England’s the whole world. Can’t grasp that it’s just a left-over, a tiny corner that the bombs happen to have missed. But what about the new kind of men from eastern Europe, the streamlined men who think in slogans and talk in bullets?

Our protagonist, forty-five year old George Bowling, is a disgruntled and unhappily married Englishman who works in insurance. When the story begins, we see him getting ready to run an errand. He has the day off and needs to pick up his new set of false teeth. Thinking about the false teeth depresses him, as he is freshly reminded that he is no longer the young and virile man he once was. To top it off, his obesity is a source of continual embarrassment to him. However, when he thinks about some money he has won at the horse races, Bowling finds his spirits perking up. He briefly toys with spending the money on his wife and kids but thinks better of it.

A good husband and father would have spent it on a dress for Hilda (that’s my wife) and boots for the kids. But I’d been a good husband and father for fifteen years and I was beginning to get fed up with it.

Bowling thinks of his life as a sort of prison; he feels oppressed and marginalized by his humdrum existence.

Because, after all, what IS a road like Ellesmere Road? Just a prison with the cells all in a row. A line of semidetached torture-chambers where the poor little five-to-ten-pound-a-weekers quake and shiver, every one of them with the boss twisting his tail and his wife riding him like the nightmare and the kids sucking his blood like leeches.

As Bowling visits his old childhood haunts later in the novel, he is struck by how things have changed. He experiences grief at this loss which has been occasioned by the advance of industrialization. In Bowling's mind, the new changes have destroyed the last vestiges of natural beauty which had imbued his youth with such pleasure. So, the main theme is loss: loss of individuality, loss of virility, and the loss of a viable national identity. This loss is symbolized by Bowling's set of false teeth.