Dear Juvy,

 With a score of 200, you are obviously qualified but you shall not get a seat in government colleges. There Used to be  separate exam for bams bhms bums seats but now Neet ug is the entrance exam conducted for admissions to mbbs and BDS/BAMS/BHMS seats in various medical college of india. 

As per your query about the marks required for BDS, it will vary every year based on the difficulty level of ques paper and number of students scoring that mark

It also depends on college you targeting like govt or private... Through STATE QUOTA 85%  Or ALL INDIA QUOTA 15 %.,But going by previous years trend for government college in obc category 450-550 will be a safer score.. If you target private it will around 400-500

Talking about BDS admissions via OBC category as per the Medical Council of India, you must be getting a percentile of above 50 the Neet examination to qualify in that regard, having passed your boards with 50% aggregate in physics, chemistry and Biology

However these statistics and numerical may vary depending on whether you are wanting to get admitted to a college in your state where the 85% state reservation or you want a college across India using the 15% all India quota, also it would depend if you want a government college or private college

Yes to get into any college across India whether,  private or government using either state of all India quota the 50th percentile should suffice for you

But if you want one of the better colleges at the government sector in your state then I think you need to lift your scoring above 380
You want to avail one of the best BDS colleges in India at the government sector using your all India rank usually you should be trying to score near 400
You might just clash with some of the not so well reputed medical colleges with this rank as well,

BAMS and BDS have somewhat similar cutoff as nowadays students take admission to these courses .

BDS - 450+ for Govt Colleges and 400+ for Private Colleges

BAMS - 440+ for Government colleges 400+ for Semi Government and 350+ for Private

BHMS - 300+ should suffice because there are only private colleges.

Hopefully it shall be of help!