Hello and welcome to our forum,
Genital HPV is transmitted through direct skin to skin contact when an infected area comes into direct contact with mucous membranes or the delicate skin of the genital area. This can occur through genital to genital contact, vaginal and anal sex.
The exact risks of contracting HPV through oral sex are currently unknown. It may be possible to contract HPV through performing oral sex, though the mouth appears to be a less hospitable environment for HPV than the genital area. Each type of HPV tends to infect a specific skin area, making it unlikely for genital types of HPV to become established and create disease orally. Research shows that it is uncommon for HPV to be found in the mouth in the form of warts (or lesions). A common recommendation is not to perform oral sex on a partner with genital HPV while lesions are present.
Latex barriers (like dental dams and condoms) may provide some protection against the transmission of HPV with a new partner. However, barriers are limited to only providing protection for skin that is covered. If virus is present on skin that is not covered, and there is skin-to-skin contact with that area, then transmission may still be possible. Nonetheless, we recommend the use of latex barriers to reduce the risks of contracting HPV and other STDs. Read more about this at http://www.ashastd.org/learn/learn_prevention.cfm
and for a dental dam overview go to http://en.wikipedia.org/wiki/Dental_dam
Some experts believe that removing genital warts may lower the risk of transmission since it reduces the areas of tissue that contain most of the virus. Removing warts cannot guarantee that the risk of transmission is removed. However, if no symptoms recur in the subsequent months following treatment, the chance of transmission dramatically decreases, and some researchers consider the possibility of being contagious during this time would be minimal to remote.
I hope this helps. All the best,