You graduated with a 4.0 and 97 on the PCAT and went to PR?!! WHY!?!?! I'm sure you'll get into UPR SDM, you just need to make sure dentistry is right for you. Is there any particular reason why dentistry and not medicine or any other field? Have you been exposed to working/shadowing in the field of dentistry?
Lastly, I think it's best to reevaluate every situation and plan out exactly what you will be doing for that 1.5 year gap. $15,000 in loans isn't bad at all, I'm sure you can find a part-time job to pay a good chunk of that off.
I'm considering dropping out of pharmacy school for dentistry. I know it's also saturated, but it doesn't look as bad as pharm. I wouldn't be working overnight or New Years'. I wouldn't have to deal with customers demanding me to work faster because they don't know what my job is. As a dentist, I think the overall work conditions would be better and I'd actually enjoy doing my job. I don't have to be rich, but even with saturation dentists make more money than pharmacists. Patients would actually see me as a healthcare provider and respect me more. I could eventually do my own thing, have my own business and be my own boss.
Hmm... I would start shadowing a dentist right now until you finish out this semester of pharm school (if you haven't already) then at the end of the semester if you feel it's truly the right field for you, then go for it. I would start with becoming an registered dental assistant to get more exposure to the field so when you do apply for dental school, you have a valid story and exemplify a solid commitment to dentistry so it doesn't look like you just dropped pharm school for money or anything like that.
Good luck! I think you'll do well.