MJDF Oral & Dental Pathology 3

Question 1

What is the most common cause of a periapical abscess?

Accepted Answer

Bacterial infection of the pulp due to deep caries causing pulp necrosis

Answer

Periapical abscess most commonly results from bacterial infection of a necrotic pulp (secondary to deep caries), spreading through the apical foramen to cause periapical inflammation and pus formation.

Question 2

What differentiates a true cyst from a pseudocyst histologically?

Accepted Answer

A true cyst has an epithelial lining; a pseudocyst lacks epithelial lining

Answer

By definition, a true cyst has a cavity lined by epithelium surrounded by connective tissue; a pseudocyst (e.g., aneurysmal bone cyst) lacks this epithelial lining.

Question 3

Which stain is used to identify Candida hyphae in a mucosal biopsy?

Accepted Answer

Periodic acid-Schiff (PAS) stain

Answer

PAS stain highlights the polysaccharide-rich cell walls of Candida hyphae and pseudohyphae in a bright magenta colour, making it the standard histochemical stain for fungal identification in tissue sections.

Question 4

What is the histological difference between hyperkeratosis and dysplasia in oral leukoplakia?

Accepted Answer

Hyperkeratosis is excess keratin without cellular atypia; dysplasia involves cellular and architectural atypia

Answer

Hyperkeratosis is increased keratin production without cytological atypia and has a lower malignant potential; dysplasia involves both architectural and cellular abnormalities and is the true precancerous change.

Question 5

What is the mechanism of bone resorption in a dentigerous cyst?

Accepted Answer

Prostaglandins and cytokines (IL-1, TNF) from the cyst lining stimulate osteoclast activity

Answer

Cyst expansion is driven by osmotic pressure and prostaglandins/cytokines released by the cyst lining, which stimulate osteoclasts at the bone-cyst interface to resorb alveolar bone.

MJDF Part 1 Practice Test

MJDF Part 1 Practice Test

MJDF Oral & Dental Pathology 3