Yes, you can do MD in Psychiatry after successful completion of BDS.

As the minimum eligibility for MD in Psychiatry is successful completion of any of MBBS, DMS, BHMS, and BDS.

For Diploma in Psychiatric Medicine, the minimum qualification required is MBBS with a minimum of 50% marks. If anyone has done some other medical course which is equivalent to MBBS degree, then also they are eligible. In fact, M.D. students who have completed any specialization which is related to psychiatric medicines, are also eligible to study this course.