MFDS Oral Biology 2 — Questions and Answers
Question 1: Which growth factor is most critical for the initiation of tooth development?
- TGF-β1
- BMP-4
- FGF-8 (Correct answer)
- EGF
Correct answer: FGF-8
FGF-8 (fibroblast growth factor 8) is expressed in the oral epithelium and is one of the earliest signals initiating tooth development.
Question 2: The epithelial cell rests of Malassez are remnants of which structure?
- Dental lamina
- Enamel organ
- Hertwig's epithelial root sheath (Correct answer)
- Reduced enamel epithelium
Correct answer: Hertwig's epithelial root sheath
After root formation, fragments of Hertwig's epithelial root sheath persist in the periodontal ligament as the epithelial cell rests of Malassez.
Question 3: What is the approximate pH at which enamel begins to demineralise?
- 4.0
- 5.5 (Correct answer)
- 6.2
- 7.0
Correct answer: 5.5
The critical pH for enamel demineralisation is approximately 5.5, below which the oral environment becomes undersaturated with respect to hydroxyapatite.
Question 4: Which component of saliva provides the primary antimicrobial defence against oral bacteria?
- Amylase
- Mucin
- Lactoferrin
- Secretory IgA (Correct answer)
Correct answer: Secretory IgA
Secretory IgA is the predominant immunoglobulin in saliva and acts by aggregating bacteria and blocking their adhesion to oral surfaces.
Question 5: Which stage of tooth development is characterised by proliferation of the enamel organ into a cap shape?
- Initiation
- Bud stage
- Cap stage (Correct answer)
- Bell stage
Correct answer: Cap stage
During the cap stage the enamel organ expands and differentiates into inner and outer enamel epithelium, stellate reticulum and stratum intermedium.
Question 6: What is the primary function of the stratum intermedium in the developing tooth?
- Secretion of enamel matrix proteins
- Support of ameloblast function (Correct answer)
- Formation of root sheath
- Production of dentine
Correct answer: Support of ameloblast function
The stratum intermedium is thought to support the metabolic activity of the inner enamel epithelium (ameloblasts) via enzyme activity and gap junction communication.
MFDS Oral Biology 2
Which growth factor is most critical for the initiation of tooth development?