Depends on how "not good" it is.. But if you had met the minimum requirement for most college which is 3Cs for any 3 of these science subjects (BIO, CHEM, PHY, MATHS), then there shouldn't be any problem to apply for dentistry. However, some schools have higher requirements. For mahsa and segi, I couldn't provide much details, I think segi's dental course is pretty new? u to have check with others. Sry, i couldn't help much. =x I applied dental course as well, but my choice is PIDC and manipal.