ORE Part 1 Oral Biology & Pathology 3

Question 1

What is the mechanism of action of fluoride in preventing dental caries?

Accepted Answer

Fluoride incorporates into hydroxyapatite to form fluorapatite (more acid-resistant); enhances remineralisation; inhibits bacterial enzymes

Answer

Fluoride's anti-caries effect is multi-factorial: (1) substitution into hydroxyapatite forming fluorapatite (acid-resistant), (2) enhancing remineralisation post-acid attack, and (3) inhibiting bacterial enolase enzymes reducing acid production.

Question 2

What is a 'radicular cyst' (periapical cyst) and what stimulates its formation?

Accepted Answer

An inflammatory odontogenic cyst arising from the rests of Malassez, stimulated by inflammatory mediators from a non-vital infected tooth

Answer

The radicular (periapical) cyst is the most common odontogenic cyst overall. It develops from epithelial rests of Malassez in the PDL, stimulated to proliferate by inflammatory mediators from pulp infection/necrosis.

Question 3

What is the significance of 'dark zones' in enamel caries histology?

Accepted Answer

Dark zones contain small pores filled with organic material and represent an area of remineralisation activity at the advancing front of early caries

Answer

In the histology of early enamel caries, the dark zone (beneath the translucent zone at the lesion front) shows small pores with remineralisation activity — it is a zone of repair. This underpins the concept of treating early lesions by remineralisation.

Question 4

What is 'amelogenesis imperfecta'?

Accepted Answer

A hereditary condition affecting enamel formation causing hypoplasia, hypomineralisation, or hypomaturation — teeth affected throughout the dentition in both dentitions

Answer

Amelogenesis imperfecta (AI) is a group of hereditary conditions affecting enamel formation genes (AMELX, ENAM, MMP20 etc.). It causes enamel defects ranging from hypoplasia (thin) to hypomineralisation (soft/discoloured) affecting all teeth.

Question 5

What cells initiate the inflammatory response in gingivitis?

Accepted Answer

Neutrophils and lymphocytes responding to bacterial biofilm products at the gingival margin

Answer

Early gingivitis is characterised by neutrophil migration from the junctional epithelium vasculature in response to bacterial LPS and other virulence factors. Lymphocytes (T cells) accumulate in the established lesion.

ORE Part 1 Practice Test

ORE Part 1 Practice Test

ORE Part 1 Oral Biology & Pathology 3