MJDF Restorative Dentistry Principles 2

Question 1

Which of the following BEST describes the 'biologic width' in relation to crown preparation and restoration placement?

Accepted Answer

The combined dimension of junctional epithelium and connective tissue attachment above the alveolar crest, approximately 2mm, which must not be violated by restoration margins

Answer

Biologic width (approximately 2mm) represents the natural seal of junctional epithelium (~1mm) plus connective tissue attachment (~1mm) above the alveolar crest. Restoration margins placed too close to or into this zone cause chronic inflammation, bone loss, and gingival recession.

Question 2

What is the MAIN advantage of using glass ionomer cement (GIC) as a restorative material in primary (deciduous) teeth?

Accepted Answer

GIC releases fluoride ions, promotes chemical bonding to tooth structure, and is biocompatible, reducing secondary caries risk

Answer

GIC's key advantages in primary dentition include: fluoride release (cariostatic effect on adjacent margins and dentine), chemical adhesion to enamel and dentine (no etching needed), and biocompatibility — important in the vulnerable primary dentition environment.

Question 3

A patient presents with a fractured upper central incisor. The fracture line extends through enamel and dentine but does not involve the pulp. What is this classified as and how should it be managed?

Accepted Answer

Ellis Class II fracture — requires dentine protection and restoration with composite resin bonding, with monitoring of pulp vitality

Answer

An Ellis Class II fracture (uncomplicated crown fracture) involves enamel AND dentine without pulp exposure. Management prioritises protecting the exposed dentine (to prevent pulp damage) and restoring the tooth with composite resin.

Question 4

What is the purpose of 'matrix bands and wedges' during the placement of a Class II composite restoration?

Accepted Answer

To create a temporary wall replacing the missing tooth surface, provide contact point formation, and prevent gingival flash of composite material

Answer

Matrix bands recreate the missing proximal wall and contact point during Class II restorations. Wedges stabilise the band, separate the teeth slightly to compensate for band thickness, and prevent composite from being extruded into the gingival crevice.

Question 5

Which of the following describes the SMEAR LAYER in the context of dentine bonding?

Accepted Answer

A thin layer of amorphous debris (cut dentine, bacterial remnants) deposited on dentine surfaces during preparation that must be either removed or modified for optimal bonding

Answer

The smear layer is a thin, compacted layer of organic and inorganic debris created during cavity preparation. It blocks dentinal tubules and reduces bond strength — adhesive systems either remove it (etch-and-rinse) or incorporate/modify it (self-etch) to create adhesion.

MJDF Part 1 Practice Test

MJDF Part 1 Practice Test

MJDF Restorative Dentistry Principles 2