If you have a handful of schools that you are specifically interested in, you should contact them and ask them what their preference is. I was in your same shoes last year. I contacted all admissions departments of schools that I was interested in. My dream DDS program responded that I definitely don't need to pursue a masters. They put more emphasis on shadowing hours and a more solid DAT. This was a relief. I accrued over 300 shadow hours and successfully improved my DAT. I took a few post bach classes for good measure and for other schools. I received an interview for my efforts. I guess if you are still young and your ECs and DAT are not stand out, you might consider a masters program.