I personally knew a woman who survived several bouts of flu, multiple other health conditions, plus beat cancer, but died from an infected tooth. Just because someone finally succumbs to one illness, that doesn't mean that previous illnesses were less serious.
Tooth infections are far more serious than most folks give them credit for. Coincidentally, I was talking to my electrician only yesterday, on the subject of teeth, he caught me with my dentures out, hate those things. A relative of his had a blood workup and the news was not good, death was even discussed, and multiple tests were undertaken. After eliminating a number of possibilities, they finally tracked to oral infections. Once that was addressed, within a month or so her blood tests came back normal.
People need to take good care of their teeth, but many don't, dental care is not covered in our national health system, probably should be as it can lead to a higher cost on the medical side. Cosmetic issues OTOH, people can pay for themselves.