the "american family physician" suggests that lesbian and bisexual women "cover sex toys that penetrate more than one person's vagina or anus with a new condom for each person" and to "consider using different toys for each person", to use a protection barrier (for example, a latex sheet, dental dam, cut-open condom or plastic wrap) during oral sex and to "use latex or vinyl gloves and lubricant for any manual sex that might cause bleeding unprotected contact with a sexual partner's menstrual blood and with any visible genital lesions". however, there "is no good evidence" that using a dental dam reduces sti transmission risks between women who have sex with women; studies show that using a dental dam as a protection barrier is rarely practiced, and that, among women who have sex with women, this may be because the individuals have "limited knowledge about the possibilities of sti transmission or [feel] less vulnerable to stis [such as hiv]".