YABU-to yourself...
I ignored a molar that had cracked, very quickly adapted to not eating that side etc, all was good. Then it started niggling one night...nothing major, it'd settle, I thought. By morning after very little sleep it was puffy and by afternoon the side of my face had swollen to the point where I was unable to open my mouth more than inch. I managed to get an emergency appointment with my dentist for the next morning and spent the night sobbing and banging my head against the radiator, I've never felt such agonising, unrelenting pain in my life.
The dentist couldn't examine me obviously so prescribed me antibiotics and told me to take ibuprofen to reduce the swelling and return in three days. By that afternoon I was vomiting and just before dinner I was admitted to hospital as the swelling went from my ear across to my nose then down my face and finished just under my jawline, it was pressing on my throat.
Tests showed that the infection had entered my bloodstream (sepsis) and was making me very poorly indeed, I spent over a week in hospital on IV antibiotics and left with more. It took a fortnight for the swelling to disappear completely and I ended up losing the tooth plus some surrounding jawbone. A filling would have been a slightly uncomfortable injection then some unpleasant sound effects for half an hour, it took weeks to recover properly.
Please, please, please go get it filled, it's not nice, I know it's not, I hate the dentist, but it's not worth the risk, it's really not.