While a dentist youll be hunched over focusing intently on your work for a large part of your day and after years of doing this you will develop a hunchback and many back problems. Here are some tips for that:
--Pull ups will be the best workout you can possibly do to prevent and even fix a hunchback and other back problems.
--Laying on your back on one of those large yoga balls for 10+ minutes will also help greatly for preventing/fixing hunchback and back pain.
--Strengthen your posterior chain (exercises like foam roller and glute bridges are good, google for more exercises); when you sit for long periods of time your gluts, hamstrings, and lower back muscles atrophy due to lack of use and this will open you up to a whole host of potential risks for debilitating injuries while in the gym and in your day-to-day life, with your risk increasing as you age. Side benefit: your butt will hurt less while sitting in one place for a long time thanks to the added muscle acting as a cushion.
--Do your typical back workouts (google if you dont have any): Doing rows on the machine or w/ free weights is excellent for your back and posture. Shoulder shrugs will give you a nice thick and strong neck as well, which will prevent neck injuries to a certain degree and has the added bonus of making you look better if youre a guy. Deadlift and squats are good but there is no need to showoff your strength by using very heavy weights because it is guaranteed you will hurt yourself if you push yourself too hard.
--Cardio: If youre a guy, run/sprint (not jog) for 10/15 minutes a few times a week, it'll keep your HGH and testosterone levels at a healthy level and this will keep you (and your back) strong and if injury does happen youll be able to recover faster. So much about health is about maintaining the right levels of hormones. (Jogging for long periods of time is unhealthy for guys. Dont believe me? Compare the body of an Olympic sprinter with a professional marathon runner.) Apologizes, girls I dont know if this will be beneficial or even applies to you.
--etc etc
Workout your entire body, not just your upper body like some people do. Your body really does run more efficiently and is less prone to injury when all your muscles are worked on and none are neglected. You dont have to be committed to the same level as a bodybuilder, 3 times a week for about an hour each session is fine. Focus on form (doing the exercises right), thats whats most important.
How did I figure this out? Easy. Long periods of time studying puts a very similar type of back tension that dentists tend to experience on me and after I took a break from the gym the tension and mild backaches became annoying so I read up and tried a bunch of things to resolve the problem.