MJDF Part 1 - Membership of Joint Dental Faculties Restorative Dentistry Principles 1

Question 1

When performing stepwise excavation of a deep carious lesion approaching the pulp, what is the PRIMARY rationale for leaving softened dentine over the pulp on the first appointment?

Accepted Answer

To allow remineralisation of affected dentine and secondary dentine deposition, reducing the risk of pulp exposure at re-entry

Answer

Stepwise excavation exploits the capacity of affected (not infected) dentine to remineralise when sealed from the oral environment. The temporary seal stimulates tertiary dentine formation, so that at re-entry the remaining carious tissue is firmer and the risk of iatrogenic pulp exposure is substantially reduced.

Question 2

The 'ferrule effect' in the context of a post-retained crown is BEST defined as:

Accepted Answer

Encircling a minimum of 1.5–2 mm of sound coronal tooth structure above the finish line with the crown margin

Answer

The ferrule effect refers to the crown encircling at least 1.5–2 mm of sound dentine above the core margin. This band of tooth structure significantly resists lateral forces, prevents root fracture, and improves the resistance form of the restoration — it is considered more important than post design for long-term prognosis.

Question 3

Which statement BEST distinguishes a total-etch (etch-and-rinse) adhesive system from a self-etch adhesive system?

Accepted Answer

Total-etch systems apply phosphoric acid separately then rinse before priming, while self-etch systems use an acidic monomer primer that simultaneously conditions and primes without a rinse step

Answer

In total-etch systems, 35–37% phosphoric acid is applied, thoroughly rinsed, and then primer and bond are applied to moist dentine. Self-etch systems incorporate acidic functional monomers in the primer that demineralise and infiltrate simultaneously without a rinsing step, reducing technique sensitivity but generally producing less distinct enamel etching.

Question 4

A heavily restored, endodontically treated lower first molar has lost both marginal ridges. The patient is otherwise dentally fit and the tooth is functional. What restorative approach is MOST appropriate?

Accepted Answer

Cuspal coverage restoration (e.g. onlay or crown) to protect the remaining tooth structure

Answer

Loss of both marginal ridges combined with endodontic treatment dramatically increases the risk of catastrophic cuspal fracture, as the tooth is both structurally weakened and less sensitive to damaging loads. Cuspal coverage distributes occlusal forces and prevents vertical root fracture, making it the evidence-based choice in this scenario.

Question 5

Which material is now considered the GOLD STANDARD for direct pulp capping, having largely superseded calcium hydroxide in contemporary practice?

Accepted Answer

Mineral trioxide aggregate (MTA)

Answer

MTA has superior biocompatibility, an excellent marginal seal, and induces a more complete and consistent dentine bridge than calcium hydroxide. Studies show calcium hydroxide-induced bridges frequently contain tunnel defects and are associated with internal resorption, whereas MTA produces a denser, more reliable hard-tissue response.

MJDF Part 1 Practice Test

MJDF Part 1 Practice Test

MJDF Part 1 - Membership of Joint Dental Faculties Restorative Dentistry Principles 1