As already mentioned, can be caused by several factors, gum disease can ultimately lead to tooth loss. The gums can be injured as a result of brushing too hard or eating sharp food. The injury could be a major cause of pain and swelling of the gums. Physical injury to the gum tissue can also cause the development of canker sores. However, the condition usually resolves itself within a week or so. Gingivitis is a mild gum disease, which causes inflammation or swelling of the gums and gum disease. This disease also makes the gums more susceptible to bleeding, due to a minor injury or irritation. The disease is mainly caused by food particles or plaque that accumulates in the spaces between the teeth and gums.