Gum recession can be caused by many factors. Age, orthodontics, grinding, smoking, and other oral habits, all can affect gum recession. Most commonly however, gum recession is caused by AGGRESSIVE BRUSHING.
Many people think the harder they brush their teeth, the cleaner they will be. This is the WRONG philosophy! Soft bristled tooth brushes should always be used, brushing should be done after every meal, and you should always brush for a full 2 minutes. Here is a short video that outlines the proper technique:
Gum recession is a problem because it exposes the softer, more decay prone, root surface, and can also cause teeth to be hyper sensitive.
The options for treatment include gingival grafting to cover the exposed root surfaces, or individual gum line fillings to protect them. Whatever treatment option you and your dentist chose, using a soft toothbrush with the right technique is imperative.