I would not do a 2-year mater's. There are plenty of 1 year master's that are also connected to dental schools. BU has an oral health master's that is 1-year. Otherwise, there are a TON of MBS connected to dental schools as well. I would recommend doing a 1-year one that is connected to the dental school you want to attend, that way you can apply a year earlier.
Also, what is your gpa and DAT? you might not need a master's.