Yes sure, here I am suggesting you the names of some good diploma courses which can be done after completing BDS (Bachelor of Dental Surgery:

Diploma in Aesthetic Dentistry
Diploma in Implantology
Diploma in cosmetic Dentistry
Diploma in Laser Dentistry
Diploma in Research Methodology
Diploma in Endodontics
Diploma in Prosthodontics
Diploma in Oral Medicine
Diploma in Oral Surgery
Diploma in Conservative dentistry
Diploma in Dental materials
Diploma in Periodontic
Diploma in Pedodontics
Diploma in Community Dentistry