See Gemara Ketubbot 10a. There two types of Taanat betulim. Firstly Taanat Damim, he claims that there was no blood, secondly Taanat "opened door". The first is valid for a little girl and for an adult (> 12) woman. The second is valid only for a girl little than 12½. There are families of ill girls who have not noticeable bleeding, and therefore there is no Taanat Damim. For Taanat opened door, the man cannot argue it if he's not accustomed with sexual relationships. There is no suspicion of lie because he would not lose the wedding expanse, but doubt about his insight. All this rules are listed in SA EH 68.
Consequences of Taanat betulim nowadays that Nisuin are immediately after Kiddushin is monetary only, not to make her pesula because of adultery.
If he wanted a betula Davka, his Taanat Damim isn't sufficient to claim that ketbba needs to be resdtitued because her claim is not nothing. She could argue that she was betula after an Oath.
The monetary challenge regards the 100--200, not the supplement.
There are two differences between nowadays an Gemara times. Today bride is adult, and there is no safek adultery between Kiddushin and nisuyin.
I'd seen multiple articles and as I assumed there is still Taanat betulim today.