ORE Part 1 Dental Anatomy and Histology 2

Question 1

What is the primary mineral component of dental enamel?

Accepted Answer

Hydroxyapatite

Answer

Dental enamel is composed of approximately 96% inorganic material by weight, primarily in the form of hydroxyapatite crystals (Ca10(PO4)6(OH)2). These crystals are organised into enamel rods, making enamel the hardest biological tissue in the human body.

Question 2

The cementoenamel junction (CEJ) shows three possible relationships. Which is the most common arrangement?

Accepted Answer

Cementum overlaps enamel

Answer

In approximately 60% of teeth, cementum overlaps the enamel at the CEJ. In about 30%, they meet edge to edge, and in approximately 10%, there is a gap exposing the underlying dentine, which can contribute to cervical sensitivity.

Question 3

Which cells are responsible for forming cementum?

Accepted Answer

Cementoblasts

Answer

Cementoblasts are the specialised cells responsible for forming cementum. They originate from the dental follicle (ectomesenchyme) and deposit cementum matrix on the root surface. Some cementoblasts become entrapped within the cementum they produce, becoming cementocytes.

Question 4

The dental papilla gives rise to which structure of the developed tooth?

Accepted Answer

Dentine and pulp

Answer

The dental papilla is the ectomesenchymal condensation that forms the core of the developing tooth germ. It differentiates into odontoblasts (which form dentine) and the dental pulp. The dental follicle, in contrast, gives rise to cementum, periodontal ligament, and alveolar bone.

Question 5

Which permanent tooth is the first to erupt in the mouth?

Accepted Answer

Lower first molar

Answer

The lower first permanent molar is typically the first permanent tooth to erupt, usually appearing at approximately 6 years of age. It erupts distal to the second deciduous molar and is often mistaken for a primary tooth by parents because no primary tooth is lost during its eruption.

ORE Part 1 Practice Test

ORE Part 1 Practice Test

ORE Part 1 Dental Anatomy and Histology 2