What causes periodontal disease?

The main cause is bacterial plaque. Plaque is the collection of bacteria that naturally harbored in the oral cavity.
Not all of the over 300 microbial species present in the mouth cause gum disease, but only some of these species are considered pathogenic. For some bacteria cause the development of periodontitis, it is necessary that certain conditions occur.
First of all, the patient should be predisposed or susceptible.
In addition to genetic factors other conditions or behaviors can promote or exacerbate periodontal disease. These factors are such as poor oral hygiene, subgingival calculus and above, diabetes, cigarette smoking and the presence of parafunctions such as grinding and clenching of teeth during the night.