NBDHE Scientific Basis of Practice 3

Question 1

Prostaglandin E2 (PGE2) plays what role in the pathogenesis of periodontal disease?

Accepted Answer

It is a potent mediator of bone resorption, stimulating osteoclast activity and contributing to alveolar bone loss

Answer

PGE2, produced by macrophages and fibroblasts in response to bacterial LPS and cytokines, stimulates osteoclast differentiation and activity via RANKL upregulation, driving alveolar bone destruction in periodontitis.

Question 2

The 'red complex' periodontal pathogens identified by Socransky et al. include which three organisms?

Accepted Answer

Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola

Answer

The red complex (Socransky 1998) — P. gingivalis, T. forsythia (formerly B. forsythus), and T. denticola — shows the strongest association with clinical parameters of periodontitis severity and active disease.

Question 3

In epidemiological studies of oral health, what does the term 'confounding variable' mean?

Accepted Answer

A variable that is associated with both the exposure and the outcome, distorting the apparent relationship between them

Answer

A confounder is associated with the independent variable (exposure) and is an independent cause of the outcome, making it appear that the exposure causes the outcome when the true cause may be the confounder.

Question 4

Which enzyme produced by periodontal pathogens is responsible for degrading the collagen of the periodontal ligament and bone matrix?

Accepted Answer

Matrix metalloproteinases (MMPs), particularly collagenase (MMP-8 and MMP-1)

Answer

Matrix metalloproteinases, especially MMP-8 (neutrophil collagenase) and MMP-1 (interstitial collagenase), produced by both host cells and bacteria, degrade collagen types I, II, and III in the periodontal ligament and connective tissue.

Question 5

The saliva has protective functions against dental caries. Which salivary component acts as a buffer to neutralize acidic pH in plaque?

Accepted Answer

Bicarbonate ions (HCO₃⁻), along with phosphate buffers and proteins

Answer

Bicarbonate is the primary salivary buffer; as salivary flow increases (stimulated), bicarbonate concentration rises to neutralize acids produced by plaque bacteria and maintain plaque pH above the critical 5.5 threshold.

NBDHE Test Practice Test

NBDHE Test Practice Test

NBDHE Scientific Basis of Practice 3