Some points of clarification
1. CBSE - scores are going up each year. There was a time when one could get into OMFS with a 40. Those days are gone. If NYU and Jacobi (Einstein) have tuition free medical school for their OMFS residents, what kind of scores do you think their OMFS candidates are achieving? Should dentist anesthesiologists be held to a lower standard? If putting in the time to study now is a deterrent, then residency is not for you.
2. Letters of rec - letters should come from people who have taught, supervised, and critiqued you. A dean's letter is a must. If you did a GPR or prior residency, that director must provide a letter. A group/practice leader in dental school for D4s is a must. These are the people who can give directors insights as to how you deal with criticism, maturity, bedside manner, team player, and are you teachable. Getting a big name DA doesn't mean much. Red flags are when your friend, colleague, etc writes you a letter. (Letters from a non-medical reference should only come if they demonstrate your qualities from a commitment or experience that was of significance in your life in scope and duration.) Letters from faculty/attendings who have been research mentors are nice too. 4 letters from different DAs that one shadowed for a handful of days are not going to provide meaningful insights and directors see through that. Some are too sweet to say no you a letter request but don't have anything substantive to say. A letter from a DA should come only with significant shadowing.
3. OMFS internships are not a great idea. In NY state you need to complete a GPR to do an OMFS internship. In other states, just do the GPR/AEGD. The GPR gives you a month of ED/Anesthesia. Also shows you have good judgement to improve your skills all around as a dentist should you not match. Some programs will also offer a GPR2 to the right candidate in which the second year GPR is getting extra time in the OR. The OMFS internship is doing scut work for OMFS and if they're a good little soldier maybe they will get to retract a 12 hour case or do a sedation or two. Unless they give you a plan, in writing, with some regular OR time with anesthesia, it is not worth it.
4. Cast a wide net. It is a big red flag when candidates apply to a few programs. The best program is the one you match in, so don't look down your nose at any place. Go see it for yourself. Not every program requires a GPR. It may be encouraged, but you have nothing to lose by externing and seeing the place for yourself.