Thanks for your query.
As you have recently ( less than a month ago ) undergone a dental procedure/ dental infection, this surgical abortion
should be done with proper antibiotic coverage.
Please inform your gynecologist about the same
Also, I hope the abscess
was treated by your dentist.
If not, get an opinion and examination from a dentist .
Also, why do you think you would have an abscess again in two days?
Are you having any symptoms - if yes, then all the more reason to consult a dentist
Also, since you are 20 weeks gone, you cannot obviously delay the abortion any longer.
SO, please take a dental opinion, and accordingly inform your gynecologist who would manage you as per the situation.