Dear Aspirant! First of all, a big congratulation to you for your BDS seat. See, looking at the previous years trends I would say that odds are not in your favour. But I would say that you should try in the third round also, this will give you satisfaction atleast you will not repent in future i should have tried in the third round. 

Hello candidate,

Congratulations on securing BDS seat, as you have got BDS  in two consecutive round, your chances of getting MBBS are not much. You should refer to the seat matrix/merit list for further rounds to see how many candidates are present before you, if there are few candidates before your rank then you can wait for upcoming rounds of counselling and if number of candidates is more that will decrease you chances. If number of seats left are very less as compared to candidates before your rank, in that case you join your alloted college.

Hope this helps you.