I don’t think anyone can give you definite percentages of the likelihood of getting HBV from oral sex. A lot depends on how infectious one person is and how susceptible the other is. I would guess that it would be more likely for a woman to get it from giving, than a man to get it from receiving….but that’s just a guess and the simple fact remains that it is VERY possible if one person is currently infected…. so practice safe sex. Just because oral sex is not the main route of HBV transmission, does not mean that it is any safer. I would not be willing to take a gamble just because the percentages may be lower than blood to blood transmission.
There is a vaccine available to protect against HBV infection but that doesn’t protect you from other STD’s like HIV, herpes, etc so safe sex should always be used unless you are in a monogamous relationship and are ABSOLUTLEY POSITVE of the other persons disease/health status and you are sure that the other person is being monogamous. Never assume that the other person is healthy just because they look healthy.
Best advice is: get vaccinations and practice safe sex until marriage.
NashPred is absolutely right.