Hey.

The eligiblity criteria for NEET MDS  is  that it is mandatory for applicants to possess a Bachelor in Dental Surgery (BDS) degree or a provisional pass certificate in BDS from an Indian university/dental college recognized by GoI (Government of India) as per Dentist Act 1948 or they must possess an equivalent qualification recognized by DCI (Dental Council of India). In 2018 the candidates were supposed to complete their BDS degrees from, has got recognition from GoI under Dental Act 1948, on or before October 31, 2017.

And this can only be done after you have completed your internship, hence you cannot attempt the MDS entrance before completing your internship.

Best of luck