I got in on the end of an interesting thread on DATY, but like anything in the hobby there is another side to think about.
What is a dental dam?
A. A dental dam, like a condom, is a barrier method. It is a thin, square piece of rubber which is placed over the labia or anus during oral-vaginal or oral-anal intercourse. Dental dams are most often made of thin latex rubber; however, for those allergic to latex, they are also available in silicone. Although specially-made rubber dental dams are sold in stores, plastic saran wrap from your kitchen can serve as an effective dental dam as well. A dental dam can help reduce the risk of STD transmission, including herpes, genital warts (HPV) and HIV.
Is there risk with oral sex?
Just a few thoughts.
http://std.about.com/od/riskfactorsforstds/a/oralsexsafesex.htm
It's all very well and good to say that oral sex is not safe sex, but how much of a risk are you actually taking if you choose to practice unprotected oral sex? What sexually transmitted diseases can be transferred from genitals to mouth, and vice versa?
HIV
Although oral sex is a relatively low-risk activity, particularly when compared to vaginal or anal sex, it is possible to transmit HIV through oral sex. Using latex or polyurethane condoms, female condoms, or dental dams is an effective way to reduce your chances of contracting the virus when engaging in oral sex. If you don't choose to use protection for oral sex, you should know that the risk of HIV transmission increases if the person performing the act has cuts or sores in his/her mouth, if ejaculation takes place in the mouth, and if the individual receiving oral sex has any other sexually transmitted diseases. The risk is primarily for the person performing the oral sex. Unless a partner has significant amounts of blood in his/her mouth, such as from dental surgery, oral sex is unlikely to expose the receptive partner to HIV.
Herpes
Although genital herpes and oral herpes are usually caused by different strains of the herpes virus, HSV-2 and HSV-1 respectively, it is possible for either virus to infect either site. Therefore, it is possible to transmit herpes during oral sex, and the virus can spread from either partner. Herpes is contagious even when symptoms are not present. Even though prophylactic medications, such as Zovirax (acyclovir), can reduce the likelihood of both outbreaks and transmitting the herpes virus to your partner, they can not eliminate the risk entirely. Although they should greatly reduce the risk of herpes transmission, condoms are also not completely effective in preventing transmission of herpes during oral sex, since the virus can spread from skin to skin.
HPV
It is possible to spread HPV through oral sex, and it is believed that HPV acquired while performing oral sex is a major risk factor for oral and throat cancers. HPV can also appear in the oral cavity through vertical transmission (transmission from mother to child during birth). As with herpes, it seems likely that the use of condoms or dental dams during oral sex should reduce the risk of infection, but they will not necessarily eliminate it entirely since HPV spreads via skin-to-skin contact not through bodily fluids.
Gonorrhea
In recent years, teenagers with throat infections caused by gonorrhea have often been in the news. Gonorrhea can be transmitted in both directions when oral sex is performed on a man, and throat infections with gonorrhea are notoriously difficult to treat. There is limited research to suggest that it may be possible for someone to acquire a gonorrheal throat infection while performing oral sex on a woman, but transmission in the other direction is relatively unlikely since the site of infection is the cervix -- a part of the female anatomy not reached during cunnilingus. Condoms and dental dams should be extremely effective in preventing transmission of gonorrhea during oral sex.
Chlamydia
It is possible to transmit chlamydia during fellatio, and both the recipient and the person performing the act are at risk. There has been little research on whether it is possible to transmit chlamydia during cunnilingus, but infection risk is probably similar to that for gonorrhea.
Syphilis
Syphilis is extremely easy to transmit via oral sex. In fact, in some areas of the United States, oral sex has been shown to be responsible for as many as 15% of syphilis cases. Although syphilis can only be transmitted in the presence of symptoms, during the primary and secondary stages of the disease, the painless sores it causes are easy to miss.
Hepatitis B
The research is inconclusive as to whether or not hepatitis B can be transmitted via oral sex. Oral-anal contact, however, is definitely a risk factor for hepatitis A infection, and it may also be a risk factor for hepatitis B. Fortunately both hepatitis A and B can be prevented by vaccines. If you practice rimming, you should talk with your doctor about getting vaccinated. Vaccination is a good idea in any case, and the hepatitis B vaccine is currently recommended for all children and many groups of adults.
The Bottom Line
In summary, unprotected oral sex puts you at risk for numerous sexually transmitted diseases. If you perform unprotected oral sex on your sexual partners, you should mention it to your physician. She may want to check your throat when she is screening you for other STDs.
Symptoms and tests
http://std.about.com/od/overviewofstds/u/symptomsdiagnosispath.htm
After You've Been Diagnosed With An STD...
http://std.about.com/od/treatment/u/userpath3.htm
A sexually transmitted disease diagnosis can be extremely stressful. You may feel dirty, or feel you've been betrayed. It is important to remember, however, that STDs are just diseases. You shouldn't feel bad about yourself just because you have one. At this point, it's time to talk to your doctor about STD treatment, and to your partner about responsibility. If you know who you got the STD from, they should be tested and treated as well, and you should let any former partners know that they might be at risk. More than ever, while you're being treated, you'll need to practice safe sex.
RISK
http://std.about.com/od/prevention/u/preventionpath.htm
STD prevention is more than just wearing a condom. It's making sensible sexual decisions to maintain and improve your health. Part of that requires regular screening and treatment for STDs. Another part is talking to your partners, both new and old. The most important part of STD prevention, however, is taking responsibility for your own decisions and actions. If you want to have sex, be prepared, and bring a condom or other appropriate protection. It doesn't matter if you're male or female, you need to take care of yourself. It's better to be prepared than frustrated!
http://std.about.com/od/prevention/u/preventionpath.htm#s1
TREATMENT
http://std.about.com/od/treatment/u/userpath3.htm#s1
Living with STDS
http://std.about.com/od/treatment/u/userpath3.htm#s2
. For myself none of it is a deal breaker, it just depends on the lady and what I'm in the mood for or may be thinking most of at the time as well.