Keeping your mouth clean and free of disease is an important task.
Regular visits to your dentist are important, as well as regular brushing and cleaning in between the teeth.
There are several problems to oral hygiene, a simple one would be the way you use your toothbrush.
A more complicated one, like malocclusion will make it difficult to clean your teeth. Making them susceptible to be damaged by the accumulating food remnants where bacteria colonize and form plaque.