Gum Disease Causes

DHCP with patient

Poor oral hygiene is a major cause of gingivitis1

Gingivitis is caused by plaque2

  • Gingivitis is caused by the buildup of plaque and bacteria between teeth2
  • Endotoxins and bacterial debris released by these plaque bacteria cause inflammation in the surrounding gum known as gingivitis2
  • If plaque is not removed, over time this inflammatory response can become chronic periodontitis, leading to progressive tissue destruction1

Progression of gum disease

Gingivitis is a reversible condition that develops from healthy gums when plaque around the gum line induces inflammation of the gingivae. If left untreated, chronic gingival inflammation can progress into chronic periodontitis, causing bone loss and even potential tooth loss.1,2

Healthy gums cross-section

Healthy gums

Uninflamed gingivae without any of the signs of periodontal disease. Characteristics include:

  • Pale pink and firm gingivae
  • Stippled
  • Firmly attached to teeth
  • Knife-edge margin
  • Not normally prone to bleeding on brushing or probing
Gums with gingivitis cross-section


Reversible plaque-induced inflammation of the gingivae.1Characteristics include:3

  • Change in colour of the gingivae
  • Marginal gingival swelling and blunting of the gingival papillae
  • Bleeding on probing and brushing
  • Probing depth of gingival crevice does not exceed 3mm
  • Gingival attachment remains unchanged, no bone loss

Bleeding on probing should be the primary signal to identify gingivitis.4 If a patient has gingivitis this can be reversed with a gum health regimen, but a periodontitis patient remains a periodontitis patient for life, even following successful therapy, and requires life-long supportive care to prevent recurrence of disease.4 This is one of the reasons it is so important to manage the disease before it becomes chronic.4

A new classification of periodontitis

In 2017 the American Academy of Periodontology (AAP) and the European Federation of Periodontology (EFP) along with expert participants from all over the world held a World Workshop to revise the periodontal classifications. The group was charged with updating the 1999 classification of periodontal diseases and conditions and developing a similar scheme for peri-implant diseases and conditions.5 The forms of the disease previously recognised as "chronic" or "aggressive", now grouped under a single category, "periodontitis".5

Periodontal health, gingival diseases/conditions4

Periodontal health & gingival health

  • Clinical gingival health on an intact periodontium
  • Clinical gingival health on a reduced periodontium

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 and metabolic diseases
  • Traumatic lesions
  • Gingival pigmentation

Forms of periodontitis

Necrotising periodontal diseases

  • Necrotising gingivitis
  • Necrotising periodontitis
  • Necrotising stomatitis

Periodontitis as a manifestation of systemic diseases

Classified according to the International Statistical Classification of Diseases and Related Health Problems (ICD) codes


  • Stages – based on severity and complexity of management
  • Extent and distribution: localised, generalised, molar-incisor distribution
  • Grades – evidence or risk of rapid progression, anticipated treatment response

Table adapted from Caton G et al. J Periodontol 2018; 89(suppl 1): S1-S84

Gums with chronic periodontitis cross-section

Forms of periodontitis

Periodontitis (under the new classification):4

Stage I: Initial PeriodontitisStage II: Moderate PeriodontitisStage III: Severe Periodontitis with potential for additional tooth lossStage IV: Severe Periodontitis with potential for loss of the dentition

Staging and grading Periodontitis6

Periodontitis: staging

Staging is designed to classify the severity and extent of a patient’s disease based on the measurable amount of destroyed and/or damaged tissue as a result of periodontitis and to assess the specific factors that may play a role in the complexity of long-term case management.

Initial stage should be determined by clinical attachment loss (CAL). If CAL is not available radiographic bone loss (RBL) should be used. Tooth loss due to periodontitis may modify stage definition. Complexity factors may shift the stage to a higher level.

  Periodontitis Stage 1 Stage 2 Stage 3 Stage 4
Serevity Interdential CAL 1-2 mm 3-4 mm ≥5mm ≥5mm
RBL Coronal third (<15%) Coronal third (15% - 33%) Extending to middle third of root and beyond Extending to middle third of root and beyond
Tooth loss (due to periodontitis) No tooth loss ≤4 tooth ≥5 tooth
Complexity Local
  • Max probing depth ≤4mm
  • Mostly horizontal bone loss
  • Max probing depth ≤5mm
  • Mostly horizontal bone loss
In addition to Stage II complexity:
  • Probing depth ≥6mm
  • Vertical bone loss ≥3mm
  • Furcation involvement class II or III
  • Moderate ridge defects

In addition to Stage III complexity:

Need for complex rehabillitation due to:

  • Masticatory dysfunction
  • Secondary occlusal trauma (tooth mobility degrees ≥2)
  • Severe ridge defects
  • Bite collapse, drifting, flaring <20 remaining teeth (10 opposing pairs
Extent and distribution Add to stage as description

For each stage, describe extent as:

  • Localized (<30% of teeth involved)
  • Generalized or
  • Molar/incisor pattern

Periodontitis: grading6

Grading aims to indicate the rate of progression of periodontitis, responsiveness to standard therapy and potential impact on systemic health.

Clinicians should initially assume grade B disease and seek specific evidence to shift to grade A or grade C.

  Progression Grade A: slow rate Grade B: moderate rate Grade C: Rapid rate

Primary criteria

Whenever available, direct evidence should be used.

Direct evidence of progression Radiographic bone loss or CAL No loss over 5 years <2 mm over 5 years >2 mm over 5 years
Indirect evidence of progression % bone loss / age <0.25 0.25 to 1.0 >1.0
Case phenotype Heavy biofilm deposits with low levels of destruction Destruction commernsurate with biofilm deposits Destruction exceeds expectations given biofilm deposits; specific clinical patterns suggestive of periods of rapid progression and/or early onset disease
Grade modifiers Risk factors Smoking Non-smoker
<10 cigarettes/day
>10 cigarettes/day
Diabetes Normoglycemic/no diagnosis of diabetes HbA1c <7.0% in patients with diabetes HbA1c >7.0% in patients with diabetes

Three steps to staging and grading a patient

Step 1: Initial Case Overview to Assess Disease


  • Full mouth probing depths
  • Full mouth radiographs
  • Missing teeth
  • Mild to moderate periodontitis will typically be either Stage I or Stage II
  • Severe to very severe periodontitis will typically be either Stage III or Stage IV

Step 2: Establish Stage6

For mild to moderate periodontitis (typically stage I or II):

  • Confirm clinical attachment loss (CAL)
  • Rule out non-periodontitis causes of CAL (e.g. cervical restorations or caries, root fractures, CAL due to traumatic causes)
  • Determine maximum CAL or radiographic bone loss (RBL)
  • Confirm RBL patters

For moderate to severe periodontitis (typically stage III or IV)

  • Determine CAL or RBL
  • Confirm RBL patterns
  • Assess tooth loss due to periodontitis
  • Evaluate case complexity factors (e.g. severe CAL frequency, surgical challenges)

Step 3: Establish Grade6

  • Calculate RBL (% of root length x 100) divided by age
  • Assess risk factors (e.g. smoking, diabetes)
  • Measure response to scaling and root planing and plaque control
  • Assess expected rate of bone loss
  • Conduct detailed risk assessment
  • Account for medical and systemic inflammatory considerations

For further information on the 2017 World Workshop on the Classifications of Periodontal and Peri-Implant Diseases and Conditions visit

Other periodontal conditions

  • Gingival overgrowth

    Enlarged gingivae induced by irritation, plaque, calculus, repeated friction or trauma, or an increasing number of medications.

  • Periodontal abscess

    Localised accumulation of pus located within the gingival wall of the periodontal pocket/sulcus, resulting in significant tissue breakdown. May develop in a pre-existing periodontal pocket.

  • Necrotising Periodontal Diseases (NPD)

    Necrotising Gingivitis (NG)5Acute inflammatory process of the gingival tissues with presence of nercrosis/ulcer of the interndental papillae, gingival bleeding and pain.

    Necrotising Periodontitis (NP)5Inflammatory process of the the periodontium with presence of necrosis/ulcer of the interdental papillae, gingival bleeding and rapid bone loss.

    Patients who are more predisposed to NG and NP including those with HIV/AIDS infection and immunosuppression, malnutrition, stress, tobacco or smoking. Other factors include alcohol consumption, inadequate oral hygiene, previous history of NPD, age and ethnicity.5

    Necrotising Stomatitis (NS)5Severe inflammatory condition of the periodontium and oral cavity in which soft tissue necrosis extends beyond gingiva. It typically occurs in severely systemically compromised patients.

  • Periodontitis associated with endo-periodontal lesions

    May occur in an acute or chronic form. Primary signs associated with an endo-periodontal lesions are deep pockets extending to the root apex and/or negative/altered response to pulp vitality tests.

Risk factors for periodontal disease can be divided into two categories3

Bacteria on tooth

Modifiable risk factors


  • Plaque and calculus
  • Wearing partial dentures
  • Deficient dentition including open contacts and overhanging and poorly contoured restorations
  • Anatomical factors including malpositioned teeth, furcations, root grooves and concavities, and enamel pearls


  • Poor oral hygiene
  • Smoking and tobacco
  • Stress
  • Poor nutrition
  • Diabetes mellitus (poorly controlled)
  • Taking medications that cause xerostomia

Targeting modifiable risk factors, such as poor oral hygiene, can improve gum health management and treatment outcomes

Family history

Non-modifiable risk factors3

  • Family history and genetic factors
  • Some hormonal variations, e.g. during puberty, pregnancy and menopause
  • Underlying immunodeficiency

Read more about the risk factors for periodontal disease from the American Academy of Periodontology.

Dental patient at practice reception

Barriers your patients may have to managing their gum health

Hard-to-reach areas

  • Any irregularity that makes tooth cleaning difficult can encourage the accumulation of plaque, including:7
    • Malpositioned teeth
    • Overhanging edges on fillings
    • Poorly contoured fillings
    • Some types of dentures
  • Calculus (tartar) formation may cause plaque retention7

Patients may ignore or not be aware of the signs of poor gum health

The early symptoms of gum disease may be ignored for a number of possible reasons:8

  • Lack of awareness of gum health importance (believing bleeding gums to be ‘normal’)
  • A belief that teeth are more important than gums
  • More focus on current cosmetic issues rather than on possible future issues caused by periodontal disease
  • Expect dental practitioner to fix gum issues instead of proactively managing own gum health

Help your patients on their journey to optimal gum health

Family Icon

Impact on patient quality of life

Find out about the impact periodontal disease has on patients’ daily lives.


Tooth Magnified icon


Explore an overview of diagnosing periodontal disease.


Dentist Icon


Explore an overview of periodontal disease management.


Tooth with gum icon

Gum Health

Find out more about gum disease


Corsodyl logo

The Corsodyl range

Find out how the Corsodyl range can help your patients.


Patient resources icon

Patient care resources

Download resources for your patients.