How does biofilm lead to development of periodontal diseases – introduction

Periodontal Diseases

Bacterially-induced, immune-mediated inflammatory diseases of the tissues supporting the teeth.

-Healthy sites: Well defined, precisely orchestrated, effective immune response.

-Diseased sites: Exacerbated, uncontrolled, detrimental immune response

Periodontitis – Risk Factors (multi-factorial aetiology)

• Dental plaque- primary aetiological factor

• Local factors - promote accumulation of dental plaque (calculus, restorations with overhanging margins),

• Systemic factors – modify the host-bacteria interaction (Diabetes mellitus, puberty, pregnancy, immunodeficiency

systemic factors can be further classified into…

modifiable and non modifiable

systemic - Non-modifiable (background) factors 4 

1. Age

2. Race

3. Gene polymorphism

4. Hyper-responsive phenotype

systemic - modifiable - Environmental, acquired factors: 3 

1. Smoking

2. Systemic diseases, medications

3. Psychosocial factors

Prerequisites for Periodontal Disease Initiation and Progression 3 

1. Virulent periodontal pathobionts (adhesins, co-aggregation, invasion, factors that cause tissue damage),

2. Local environment,

3. Host susceptibility (gene polymorphism, PMN defects, smoking, diabetes, immunosuppression)

Periodontal Tissues Destruction -split

• Direct action of the microorganisms (20%)

• De-regulated inflammatory (immune) response to dental plaque m.o. (disruption of protective innate immunity or unresolved inflammation) 80%

Bacterial Virulence Factors

Early colonisers are mainly using glycolysis, late colonisers use proteolysis - they use a different set of enzymes 

They can produce collagenases - destroy periodontal tissues. Toxins to osteoblasts.

Direct tissue damage or poorly controlled immune response damage - which causes tissue damage 

Specific pathobionts as late colonisers - antigens - triggers host inflammatory response - leads to tissue damage - clinical expression

Many cells can sense antigens - can produce cytokines. The duration of the inflammation depends on the ratio of cytokines - prevalence of the pro-inflammatory cytokines - reach the peak of the inflammation 

Direct and Indirect Tissue Damage

Tissue damage can occur for either combo

interleukin 1, 6 , 8 , 10