I think it would be better if you came up with your own ideas & did not use a book, which would be more personal. They want you to discuss how dentistry as a career would fulfill your personal & professional goals. It would also be good to describe what makes you unique. You may want to attend a Kaplan personal statement workshop if you can find one. Also you may want to use the search on SDN for some ideas. It took me a day to write mine, but a couple weeks to revise.