Dental School is much like having an 8 to 5:00 job, except that you will be learning new things daily. Often, it doesn't end at 5:00 either, as you will have extra studying to do, or projects to complete. It's a very exciting time, but it occupies most of your life during that time. Initially, you'll spend most of your time in class or in laboratories. Most schools try to incorporate clinical experience early on, and that will increase throughout school. By the time you get into the final year, most of your time will be spent in the treatment of patients.
If you really want to find out more, most Schools hold some type of program (IU has Dental Day), where you will learn hands-on what a Dental student does from the students themselves. They will tell you their experiences and what Dental School is like.