ABP Periodontal Pathogenesis and Host Response 3

Question 1

The 'ecological plaque hypothesis' (Marsh, 1994) proposes that periodontal disease is caused by:

Accepted Answer

Environmental shifts in the subgingival niche that select for a dysbiotic, disease-promoting microbiome

Answer

Infection by specific exogenous periodontal pathogens not present in health

Answer

An equal overgrowth of all oral bacterial species

Answer

Elimination of protective commensal organisms by antibiotic exposure

Question 2

In Page and Schroeder's histopathological stages of the periodontal lesion, the 'established lesion' is characterized by predominance of:

Accepted Answer

Plasma cells and B lymphocytes with possible pocket formation

Answer

Neutrophils in the junctional epithelium and connective tissue

Answer

T lymphocytes and macrophages in early connective tissue infiltrate

Answer

Osteoclasts actively resorbing alveolar bone

Question 3

The IL-1 gene cluster polymorphism (composite genotype +) is clinically significant in periodontology because carriers demonstrate:

Accepted Answer

Elevated IL-1α and IL-1β production, increasing susceptibility to severe periodontitis

Answer

Enhanced osteoblast differentiation and bone repair capacity

Answer

Impaired neutrophil chemotaxis and reduced phagocytic killing

Answer

Decreased complement activation and reduced local inflammation

Question 4

Epigenetic modifications implicated in periodontal pathogenesis alter gene expression WITHOUT changing the DNA nucleotide sequence through mechanisms such as:

Accepted Answer

DNA methylation, histone modification, and microRNA regulation

Answer

Nucleotide base-pair substitutions induced by bacterial toxins

Answer

Point mutations in promoter regions of cytokine genes

Answer

Somatic gene rearrangements in periodontal ligament cells

Question 5

In response to bacterial challenge in periodontitis, the junctional epithelium undergoes which critical pathological change?

Accepted Answer

Conversion to pocket epithelium and apical migration along the root surface

Answer

Hyperkeratinization to resist bacterial penetration

Answer

Increased hemidesmosmal attachment to tooth enamel

Answer

Upregulation of antimicrobial peptides sufficient to clear the infection

Question 6

Neutrophil extracellular traps (NETs) in the context of periodontal disease:

Accepted Answer

Can cause collateral tissue damage and perpetuate inflammation while targeting bacteria

Answer

Are exclusively protective and never contribute to tissue destruction

Answer

Occur only in localized aggressive (Stage III Grade C) periodontitis

Answer

Are absent from gingival crevicular fluid in chronic periodontitis

Question 7

The 'keystone pathogen hypothesis' (Hajishengallis & Lamont) best explains why P. gingivalis causes severe disease at low abundance because:

Accepted Answer

P. gingivalis disables complement and neutrophil function, enabling outgrowth of the entire dysbiotic community

Answer

Each pathogen causes a distinct disease pattern consistent with the specific plaque hypothesis

Answer

Total bacterial burden alone determines disease severity per the non-specific plaque hypothesis

Answer

Environmental factors alone select for pathogenic bacteria without a microbial driver