Ask a medical doctor or spend time searching. My perception is that trauma caused by oral intercourse is usually not significant beyond facilitating the transmission of STIs. Besides, the mouth has a very effective defense mechanism to prevent serious injury from occuring.
Anyway, the linked article doesn't explain the whole story about this STI: According to the U.S. Centers for Disease Control and Prevention[1] on genital HPV infection (oral sex is not included, but
it should be), there are more than 40 types (strains) of the virus, and HPV infects the skin and mucous membranes. The CDC claims that genital HPV is the most common STI, and that most people with it do not develop symptoms. There can be multiple infections of different viral strains[2] as well.
Envision a receptive woman having unprotected intercourse with many partners in three orifices (or a homosexual man in two). Consider that, over time, she could be accumulating different strains of high-risk HPV in her throat, on her cervix, and scattered throughout her rectal mucosa (among other locations along the way). My guess is that the risk of developing cancer increases substantially with the presence of many different HPV infections. A weakened immune system could also contribute to that. But there is some good news:
"In 90% of cases, the body’s immune system clears the HPV infection naturally within two years. This is true of both high-risk and low-risk types... A vaccine can now protect females from the four types of HPV that cause most cervical cancers and genital warts." [1]
Refs:
1.
http://www.cdc.gov/std/HPV/STDFact-HPV.htm [
archive.org snapshot]
2.
http://www.ncbi.nlm.nih.gov/pubmed/14693839