When I was a teenager I had to fill my tooth. the night before the day I had my dentist appointment I became "Mohtalem" (I had sex in dream while asleep). That morning I hurried to dentist without remembering what happened last night, so my tooth was filled and later I remembered and did Ghosl. Please tell me what I should do?

Praise be to Allah, the Lord of the World; and blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.
If your question is about whether filling one's teeth while Junub (being in the state of ceremonial impurity) has any influence on the Tahara (purity) the answer is negative. In fact, filling one's teeth does not require the person to be in a state of ceremonial purity.
But if you are asking about any prayer you performed, forgetting that you were Junub and before you perform Ghusl, the answer is that you did not commit a sin. Allah Says (interpretation of meaning): {… "Our Lord! Punish us not if we forget or fall into error, …}[2:286].
Muslim reported that Allah said answering this request: "Indeed, I did (I forgave you for what forgot or did by mistake".(Muslim)
Imams Ibn Majah and al-Baihaqi report from Ibn Abbas that the Prophet said: "(Almighty Allah forgives my Ummah's mistakes, forgetfulness, and the acts on which they are forced)".
So, you did not commit a sin. But you should make up for any prayer you prayed while Junub.
Allah knows best.