Well, yes. It’s really unhygienic. Why? Because not all people has a proper oral hygiene. Imagine your partner having cavities and caries on his teeth. And when a person has a cavity, pwede kumalat yun so kahit wala kang sira na ipin pwede ka din magka cavity. Even through kissing your partner intimately. My partner is a Dentist that’s why I know these stuffs. I hope it helps. :)