Hi Anonamous
The risk in performing oral sex on a woman (DATY) would be from infections that;
Are on the skin: Such as herpes simplex virus (HSV) type 1 and 2, syphilis and maybe the human papilloma virus (HPV).
Are in the vaginal fluid: Such as hepatitis B and HIV.
It can be difficult to work out your exact risk as it depends on a number of different factors. The big one is the type of infection e.g. someone having a HSV outbreak could pass HSV easily through DATY, while HIV is considered to be a low risk.
In regard to your tooth fracture I do not have enough experience with dental problems to say what the increased risk would be. Anytime the mouth is damaged your risk would be increased e.g. cut, tooth infection etc. I am not sure how much damage you would need to do to the tooth to break the protection that the outside of the tooth offers.
As sexually transmitted infections are just small in the amount of bacteria and viruses that find their way to our mouth I would just ask your dentist. You would not need to say it was from DATY but rather that you are concerned about bacteria/viruses that are in your mouth getting into your body through the broken tooth.
For good protection while performing DATY you could use a dental dam, or a cut condom.
Here is a link about dental dams.
http://www.sexualityandu.ca/adults/sti-4.aspx
Let us know if you want us to expand on a topic. Remember if you would like to ask me a personal question just send me a PM.
HN
www.stiresource.com