Brushing with toothpaste is important for several reasons. First and foremost, a toothpaste and a correct brushing action work to remove plaque, a sticky, harmful film of bacteria that grows on your teeth that causes cavities, gum disease and eventual tooth loss if not controlled. Second, toothpaste contains fluoride, which makes the entire tooth structure more resistant to decay and promotes remineralization, which aids in repairing early decay before the damage can even be seen. Third, special ingredients in toothpaste help to clean and polish the teeth and remove stains over time. Fourth, toothpastes help freshen breath and leave your mouth with a clean feeling.
Is brushing with toothpaste enough to fight cavities and gum disease?
No. Although brushing thoroughly after each meal helps, flossing your teeth every day to remove plaque and food particles between teeth and at the gumline is just as important. Studies show that plaque will regrow on teeth that are completely clean within three to four hours of brushing.
Source:
http://www.knowyourteeth.com/infobites/abc/article/?abc=b&iid=291&aid=1134