Why do submarine soldiers require neat teeth?

In fact, there is not much scientific basis, and you can't dive with uneven teeth. Jokes. Can't you bite the ventilator if your teeth are a little irregular? It is said that the submarine really had an accident in the war, and there was no chance of diving to escape. This is completely unnecessary consideration. The only specious scientific basis is that submarines, especially nuclear submarines, may need to dive for a long time, and it is impossible to have luxurious dentists and corresponding equipment in a narrow and closed space, so if the teeth are bad and toothache occurs, it will be in big trouble.