There are a number of factors that can cause or raise the risk of developing gum disease or gingivitis. However, one of the most common causes is the formation of dental plaque.

Poor oral hygiene with irregular teeth brushing or lack of flossing leads to a build up of dental plaque that can give rise to gingivitis.

Causes and risk factors for gingivitis

• Poor dental and oral hygiene: Lack of regular brushing and flossing of the teeth leads to the build up of food particles between the teeth and the growth of bacteria. Colonies of the bacteria develop in the form of a thin, colorless, sticky film over the teeth called dental plaque. This bacteria-containing plaque can lead to tooth and gum disease, so teeth should be cleaned regularly to help reduce the formation of this plaque.
• Formation of dental plaque: When a person consumes carbohydrates, bacteria present inside the mouth break these carbohydrates down into energy and produce acid at the same time. This acid, along with the saliva and bacteria in the mouth, forms plaque across the teeth, which eventually becomes hard and forms tartar. Tartar becomes more firmly attached to the surfaces of the teeth and can usually only be removed by a dentist. The bacteria contained in the plaque and tartar gives rise to tooth decay and affects the gums causing gingivitis.
• Smokers are at a greater risk of tooth decay and gingivitis as are those who chew tobacco.
• People with "dry mouth" are at risk of tooth and gum disease as saliva would normally serve to protect against these. Dry mouth can result from the use of certain medications including tricyclic antidepressants, anticholinergic agents, anticonvulsants, antipsychotics, antihistaminics, and antihypertensive agents.
• People with diabetes are more likely to develop infections due to high blood sugar and lowered immunity. Consequently, they are also at a greater risk of gingivitis.
• Other groups with weakened immune systems such as those on chemotherapy, immunosuppressants for HIV, or steroids are also at a greater risk of gingivitis.