Also, a lot of schools say they don't look down on taking time off, but when it comes time to choose between two similar applicants, the individual who spent that time working to get into school, as opposed to the individual who simply took time off for leisure, is going to get the leg up.
If you plan to come to an American dental school, you can't defer acceptance (NO dental school will let you defer just so you can travel) and you better demonstrate a hard work ethic towards admission, unless your GPA and DAT scores are consistently above average.
Just my $0.02.