MJDF Dental Anatomy & Physiology 3 — Questions and Answers
Question 1: What is the primary mineralisation sequence of permanent teeth in humans?
- First molars → incisors → canines → premolars → second molars → third molars (Correct answer)
- All teeth simultaneously
- Incisors before molars always
- Third molars first, then anteriors
Correct answer: First molars → incisors → canines → premolars → second molars → third molars
Permanent teeth begin mineralising in a roughly sequential pattern starting with first molars and incisors around birth, followed by canines, premolars, second molars, and finally third molars.
Question 2: What structure connects the enamel organ to the oral epithelium during tooth development?
- Dental lamina (Correct answer)
- Hertwig's root sheath
- Reduced enamel epithelium
- Dental follicle
Correct answer: Dental lamina
The dental lamina is the band of oral epithelium that ingrowths into the ectomesenchyme, connecting the developing enamel organ to the oral epithelium during tooth initiation.
Question 3: What is the function of Hertwig's epithelial root sheath?
- Determine root length and number by directing radicular dentine formation (Correct answer)
- Form the enamel of the root
- Provide blood supply to the developing root
- Form alveolar bone around the root
Correct answer: Determine root length and number by directing radicular dentine formation
Hertwig's root sheath guides root formation by inducing dentine deposition along the root outline; its fenestrations determine where root furcations develop in multi-rooted teeth.
Question 4: Which cells are responsible for enamel formation?
- Ameloblasts (Correct answer)
- Odontoblasts
- Cementoblasts
- Fibroblasts
Correct answer: Ameloblasts
Ameloblasts (from the inner enamel epithelium) secrete and mineralise enamel matrix; they are lost once enamel formation is complete, explaining why enamel cannot regenerate.
Question 5: What is the average eruption age of the maxillary permanent canine?
- 11–12 years (Correct answer)
- 6–7 years
- 8–9 years
- 14–15 years
Correct answer: 11–12 years
The maxillary permanent canine typically erupts at 11–12 years of age, often after the lateral incisor and premolars, and is the tooth most commonly impacted (after third molars).
Question 6: Which root surface has the highest risk of cementum resorption during orthodontic treatment?
- Root apex (apical third) (Correct answer)
- Cervical third
- Mid-root
- Furcation area
Correct answer: Root apex (apical third)
Apical root resorption is the most common site of orthodontic resorption, with the apical third particularly vulnerable to hyalinisation and pressure necrosis during tooth movement.
MJDF Dental Anatomy & Physiology 3
What is the primary mineralisation sequence of permanent teeth in humans?