There seems to be a belief that teens are participating in more oral sex than ever before, possibly to avoid emotional involvement, vaginal sex and pregnancy risk, partially because some teens do not think of oral sex as "real" sex, therefore do not consider themselves sexually active if they are only participating in oral sex.
A recent study by Duberstein Lindberg and Santelli, "Non-coital sexual activities among adolescents," suggests it might be true. These authors used the 2002 National Study of Family Growth data from 2,271 teens aged 15 to 19 to report that oral sex was much more common than vaginal sex, but both seemed to occur for the first time within six months.
Their results suggest that slightly more than half of the teens had engaged in oral sex, and in fact, more had participated in oral sex than vaginal sex, but their evidence suggests that female teens who are having oral sex, have only done so with one partner.
These results suggest it is very important that teens be provided education and risk counseling about the sexually transmitted infection risks associated with both vaginal and oral sex. By ignoring oral sex in sexuality education, we are allowing teens to believe they are "safe" if they are only having oral sex.