Assuming you have some natural business intuition, you aren't going to learn anything from a minor in business unless it involves some type of externship. I can't believe how little practical knowledge I gained from a business finance degree. I learned more in 1 month of working professionally than 4 years of school. If you want to do it purely out of interest that is fine but don't expect to walk away with any new practical skills.
Example: Accounting Course you will learn very basics of accounting but you will not be able to do your own accounting. You will have to hire the accounting out. You may learn some vocab and a very basic understanding of accounting, but you could have picked that up reading online in 3 or 4 hours. You will forget all of this course by the time you are done w/ D-school
Marketing: you won't learn anything that wasn't already common sense to you unless you are taking higher level marketing courses
Management: You will learn generalities towards business management, but the strategies will be so broad that many/most won't apply to running a dental office. Management is specific to individuals. You will learn far more working part time in an office setting through interactions with people. Being an employee helps you learn what motivates people and how you liked to be managed. No intro to management class is going to help you in a practical way if you have any common sense. Also, dental shadowing should give you a sense of managing employees, some dentists are great at it and some have no clue...you should be able to pick up on this pretty quickly in an office.