There is no problem to bite cotton for a long time after tooth extraction, because the purpose of biting cotton after tooth extraction is to stop bleeding by pressure, and at this time the pressure to stop bleeding is theoretically the longer the better. But generally there is no condition to keep the state of tight bite after tooth extraction, and the blood clot will be formed in about 30 minutes after tooth extraction, and then there will be no more fresh blood flowing out of the tooth extraction wound obviously, so it is OK to bite cotton ball for 30-40 minutes after tooth extraction. It is not a bad idea to extend the time further, but it will not be particularly useful in itself. To sum up, it is possible to bite cotton for a longer time after tooth extraction, but it is not necessary to bite for that long.