Gingivitis associated with plaque only
Gingival diseases modified by systemic factors
Gingival diseases modified by medications
Gingival diseases modified by malnutrition
Non-plaque-induced gingival lesions
Gingival diseases of specific bacterial origin
Gingival diseases of viral origin
Gingival diseases of fungal origin
Gingival diseases of genetic origin
Gingival manifestations of systemic conditions
Traumatic lesions
Foreign body reactions
Not otherwise specified

2017 Classification
As defined by the 2017 World Workshop, periodontal health, gingival diseases/ conditions have been categorised into the following:
Periodontal health and gingival health
Clinical gingival health on an intact periodontium
Clinical gingival health on a reduced periodontium
Stable periodontitis patient
Non-periodontitis patient
Gingivitis – dental biofilm-induced
Associated with dental biofilm alone
Mediated by systemic or local risk factors
Drug-influenced gingival enlargement
Gingival diseases – non-dental biofilm induced
Genetic/ developmental disorders
Specific infections
Inflammatory and immune conditions
Reactive processes
Neoplasms
Endocrine, nutritional & metabolic diseases
Traumatic lesions
Gingival pigmentation

Prevention
Gingivitis can be prevented through regular oral hygiene that includes daily brushing and flossing. Hydrogen peroxide, saline, alcohol or chlorhexidine mouth washes may also be employed. In a 2004 clinical study, the beneficial effect of hydrogen peroxide on gingivitis has been highlighted. The use of oscillation type brushes might reduce the risk of gingivitis compared to manual brushing.Rigorous plaque control programs along with periodontal scaling and curettage also have proved to be helpful, although according to the American Dental Association, periodontal scaling and root planing are considered as a treatment for periodontal disease, not as a preventive treatment for periodontal disease. In a 1997 review of effectiveness data, the U.S. Food and Drug Administration (FDA) found clear evidence showing that toothpaste containing triclosan was effective in preventing gingivitis.
Complications
Recurrence of gingivitis
Periodontitis
Infection or abscess of the gingiva or the jaw bones
Trench mouth (bacterial infection and ulceration of the gums)
Swollen lymph nodes
Associated with premature birth and low birth weight

Alzheimers and dementia
A new study from 2018 found evidence that gingivitis bacteria may be linked to Alzheimers disease. Scientists agree that more research is needed to prove a cause and effect link. "Studies have also found that the bacteria P. gingivalis – which are responsible for many forms of gum disease – can migrate from the mouth to the brain in mice. And on entry to the brain, P. gingivalis can reproduce all of the characteristic features of Alzheimer’s disease." Cause
The cause of plaque-induced gingivitis is bacterial plaque, which acts to initiate the bodys host response. This, in turn, can lead to destruction of the gingival tissues, which may progress to destruction of the periodontal attachment apparatus. The plaque accumulates in the small gaps between teeth, in the gingival grooves and in areas known as plaque traps: locations that serve to accumulate and maintain plaque. Examples of plaque traps include bulky and overhanging restorative margins, clasps of removable partial dentures and calculus (tartar) that forms on teeth. Although these accumulations may be tiny, the bacteria in them produce chemicals, such as degradative enzymes, and toxins, such as lipopolysaccharide (LPS, otherwise known as endotoxin) or lipoteichoic acid (LTA), that promote an inflammatory response in the gum tissue. This inflammation can cause an enlargement of the gingiva and subsequent formation.