You discontinuing B.Sc doesn't count because you have already started BDS now and your highest qualification remains 10+2 though you are studying BDS now. In your case, your qualification code will be 07. Code 07 says:

Any other examination which in scope and standard (Last 02 years of 10+2 Study comprising of Physics, Chemistry and Biology/Bio-technology; which shall include practical test in these subjects) is found to be equivalent to the Intermediate Science Examination of an Indian University/Board, taking Physics, Chemistry and Biology/Biotechnology including practical tests in each of these subjects and English.