BDS Scope

Yes, you can do PGDMES after BDS. The eligibility criteria of Symbiosis Centre for Health Pune is given below. Eligibility: MBBS BDS. BHMS B.A. MS BSMS BUMS BPT BNYS B.Sc. (Nursing), P. B.Sc. Nursing, B.Sc. (Emergency Trauma Care Technology) or its equivalent DHMS (with certified from Homoeopathic Council with its equivalence to a 5-year degree course) with minimum of 50% marks or equivalent grade from any statutory/recognised University. This programme train doctors & nurses in the field of Emergency Medical Services, focusing on pre-hospital care and create awareness and new services in the society. Further MBBS is needed for intensivist doctor.

Hey,
I am one of the best examples that you can relate to.
I've done my BDS and worked in a clinic for an year. Then gave my CAT, XAT, SNAP etc, and scored a whooping 97.36 percentile. I am currently an alumnus of XIMB-HR working in Jodhpur.
I also had a dentist amongst my seniors and one among my juniors in PG. A junior dentist gave her CAT and scored 99.2 and is an alumnus of IIM Calcutta. She didn't like being a dentist too.
Campus placements are good if you are good with your presentation skills, communication and are diligent enough. If you have a love for it, broaden your horizons, you need not stick to MHA nor think that you have wasted 5 years. It, infact, is a unique factor and helps you to get noticed.
As for me, I've never regretted choosing this path because just like you, I've always dreamed of being associated with big companies. Following your passion might not be always possible but doing what you dont like is something you might have to live with regretting for the rest of your life. Choose well.
All the best!!
Edit: An year after my MBA, I have now moved to my home state, working with Accenture. Your hardwork will pay.