Periodontal disease, also known as gum disease, is a common and serious oral health condition that affects the supporting structures of the teeth, including the gums, periodontal ligament, and alveolar bone. The etiology of periodontal disease is multifactorial, involving a combination of bacterial infection, host response, and various risk factors. Here's an overview of the etiology of periodontal disease: Dental Plaque and Bacterial Infection: The primary etiological factor of periodontal disease is dental plaque, a biofilm that forms on the teeth and gum line. Specific bacteria within dental plaque, such as Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola (often referred to as the "red complex"), are particularly pathogenic and play a key role in the initiation and progression of periodontal disease. When plaque is not adequately removed through oral hygiene practices, these bacteria can proliferate and produce toxins that induce inflammation and damage to the periodontal tissues. Host Response: The body's immune response to the bacterial infection is a crucial component in the development and progression of periodontal disease. In susceptible individuals, an exaggerated immune response can lead to chronic inflammation and tissue destruction. Genetic factors may influence an individual's susceptibility to periodontal disease by affecting the immune response and inflammatory pathways. Risk Factors: Poor Oral Hygiene: Inadequate brushing and flossing allow plaque to accumulate, increasing the risk of periodontal disease. Smoking and Tobacco Use: Tobacco use is a significant risk factor for periodontal disease and can impair the body's immune response to bacterial infection. Age: The risk of periodontal disease increases with age, partly due to cumulative exposure to risk factors and changes in the oral microbiome. Systemic Conditions: Certain systemic conditions, such as diabetes, cardiovascular disease, and immunocompromised states, can increase susceptibility to periodontal disease. Hormonal Changes: Hormonal fluctuations during puberty, pregnancy, and menopause can affect gum health and increase the risk of periodontal disease. Local Factors: Anatomy of Teeth: Misaligned or crowded teeth can create areas that are difficult to clean, increasing the risk of plaque accumulation and periodontal disease. Dental Restorations: Poorly fitting dental restorations or orthodontic appliances can contribute to plaque retention and periodontal inflammation. Environmental and Behavioral Factors: Diet: Consumption of a diet high in sugars and carbohydrates can promote bacterial growth and plaque formation. Stress: Chronic stress may impair the immune response and increase susceptibility to periodontal disease. Stages of Periodontal Disease: Gingivitis: The earliest stage of periodontal disease, characterized by inflammation of the gums (gingiva) without loss of supporting bone.

1. ETIOLOGY
OF
PERIODONTAL
DISEASE

7. THE AETIOLOGY (CAUSES) OF PERIODONTAL
DISEASES
• Aetiology is the science of causes or origins.
• Aetiological factors in relationship to periodontal disease are those
factors or agents that in some way cause, modify, or contribute to
the development of periodontal tissue injury or destruction.
• The concept of aetiology is important because both the prevention
and the treatment of dental diseases depend on a thorough
understanding of the relationship between the aetiological factors
and the pathogenesis of periodontal disease and dental caries.

8. THE AETIOLOGY (CAUSES) OF PERIODONTAL
DISEASES
• The primary factor in the aetiology of inflammatory periodontal
diseases is the accumulation and maturation of bacterial plaque
(dental biofilm) on the teeth near the gingival margin and/or in the
sulcus or pocket.
• However, the patient’s periodontal tissue response to the bacteria is
influenced by local, immune and systemic resistance factors.

9. THE AETIOLOGY (CAUSES) OF PERIODONTAL
DISEASES
• In periodontal health a balance exists between the pathogenicity of
the small amounts of bacterial plaque present on the teeth and the
patient’s resistance.
• When gingivitis or periodontitis develops, an imbalance exists
between the pathological effects of the microorganisms and the
ability of the patient’s local, immune and systemic defence
mechanisms

10. THE AETIOLOGY (CAUSES) OF PERIODONTAL
DISEASES
• Local resistance factors include the crevicular fluid, epithelial
barriers, and anatomical factors. Immune mechanisms include
hypersensitive reactions to the bacteria such as anaphylaxis or
immediate hypersensitivity, immune complex reactions, and
cytotoxic reactions.
• Systemic factors are hormonal changes such as pregnancy and blood
dyscrasias.

11. THE AETIOLOGY (CAUSES) OF PERIODONTAL
DISEASES
• Predisposing factor: A factor that renders a person susceptible to a
disease or condition.
• Contributing factor: A factor that lends assistance to, supplements, or
adds to a condition or disease.
• Risk factor: An exposure that increases the probability that disease
will occur.

12. THE AETIOLOGY (CAUSES) OF PERIODONTAL
DISEASES
• Local factor: A factor in the immediate environment of the oral cavity
or specifically in the environment of the teeth or periodontium.
• Systemic factor: A factor that results from or is influenced by a
general physical or mental disease or condition.

13. THE AETIOLOGY (CAUSES) OF PERIODONTAL
DISEASES (SUMMARY)
I. PRIMARY FACTORS
a. Dental Plaque Definition
(Dental Biofilm) Formation
Structure and Composition
Pathogenicity:
1. Microbiological Factors (Bacterial)
-invasion
-production of exotoxins,
endotoxins, surface
compone
2. Immunological Factors (host responses)
-protective
-destructive
production of enzymes-evasion of immunologic
host response

14. II. SECONDARY FACTORS
a. Local 1. Plaque retention:Calculus
Overhangs
Crowns/Bridges
Dentures
Orthodontic Appliances
Splints
2. Anatomical Factors:
Tooth position (malocclusion)
Pearls. Grooves etc.
Osseous deformities: Dihescence;
Fenestration
Functional teeth without antagonists
Open contacts
3. Occlusal Factors
4. Poor Oral hygiene
5. Smoking

15. b. Systemic
Resistance factors: crevicular fluid, blood cells, immunity
1. Drugs Diphenylhyadantoin→epilepsy
Cyclosporine A→organ transplant
Nifedipine→hypertension
2. Hormones Puberty, Pregnancy, Diabetes
3. NutritionVitamin C, Vitamin D
4. Genetic: Aggressive Periodontitis, (Juvenile,Prepubertal),
Downs Syndrome
5. Stress
6. Immune Dysfunction HIV/AIDS
7. Blood dyscrasias: Acute Leukaemia

16. THE AETIOLOGY (CAUSES) OF PERIODONTAL
DISEASES
I. PRIMARY FACTORS
a.Dental Plaque (Dental Biofilm)
Definition
Formation
Structure and Composition
Pathogenicity:

17. Dental Plaque Pathogenicity:
1. Microbiological Factors (Bacterial)
i. invasion
ii. production of exotoxins, endotoxins,

18. Two methods by which pathogenic bacteria cause disease:
• 1. Invasiveness is the ability to invade tissues. It encompasses mechanisms for
colonization (adherence and initial multiplication), production of extracellular
substances which facilitate invasion (invasins) and ability to bypass or overcome host
defense mechanisms. Most invasins are proteins (enzymes) that act locally to
damage host cells .
• 2. Toxigenesis is the ability to produce toxins. Bacteria may produce two types of
toxins called exotoxins and endotoxins. Exotoxins (extracellular protein toxins)
exotoxins are often cytotoxic and may act at remote sites (removed from the site of
bacterial growth) Endotoxin is comprised of toxic lipopolysaccharide components of
the outer membrane of Gram-negative bacteria. Endotoxin exerts profound biologic
effects on the host and may be lethal. Because it is omnipresent in the environment,
endotoxin must be removed from all medical supplies destined for injection or use
during surgical procedures.

19. COLONIZATION
Is the first stage of microbial infection-the
establishment of the pathogen at the
appropriate portal of entry.
Bacterial Adherence to Mucosal Surfaces.
In its simplest form, it requires the
participation of two factors:
a receptor and an adhesin
• The adhesins of bacterial cells
are chemical components of the
bacterial cell surface which
interacts with the host cell
receptor
• The host receptors are usually
glycoproteins on the cell surface

20. Dental Plaque Pathogenicity:
2. Immunological Factors (host responses)
i. protective
ii. destructive
Onset of the disease requires a pathogen of virulent strain and a host with the
necessary genetic factors to trigger the disease. In other words, an individual must be
susceptible to a micro-organism and this must be present in sufficient numbers. Other
bacterial species must promote or at least not inhibit the process,
while the local environment must favour the expression of virulent bacterial properties.
If the microorganism is able to evade all of these systems, it triggers the adaptive
response, i.e., specific mechanisms.

21. II. SECONDARY FACTORS
a. Local
1. Plaque retention:
• Calculus
• Overhangs
• Crowns/Bridges
• Dentures
• Orthodontic Appliances
• Splints

22. 2. Anatomical Factors:
• Tooth position (malocclusion)
• Pearls, Grooves etc
• open contacts
• Osseous deformities: Dihescence & Fenestration

23. Functional teeth without antagonists
Open contacts

24. 3. Occlusal Factors
Premature contacts between the
arches can result in trauma to the
periodontal structures
4. Poor Oral hygiene
5. Smoking

25. II. SECONDARY FACTORS
b. Systemic
Resistance factors:
crevicular fluid, blood cells, immunity
1. Drugs
Diphenylhyadantoin→epilepsy
Cyclosporine A→organ transplant
Nifedipine→hypertension

26. II. SECONDARY FACTORS
b. Systemic
2. Hormones: Puberty, Pregnancy, Diabetes
3. Nutrition: Vitamin C, Vitamin D
4. Genetic: Aggressive Periodontitis, (Juvenile, Prepubertal) ,
Downs Syndrome
5. Psychosocial Factors: Stress
6. Immune Dysfunction: HIV/AIDS
7. Blood dyscrasias: Acute Leukaemia

27. II. SECONDARY FACTORS
b. Systemic