4. Restorative Dentistry

Question 1

Function of acid-etch
Advantage/disadvantage of linings

Principles of cavity preparation (6)

Features of internal design modification (4)

Answer 1

Roughen surface, improving bond
Protect pulp, may cause secondary caries

Remove as little healthy tooth tissue as possible: remove enamel caries, remove enamel to identify ADJ caries, remove peripheral (ADJ) caries then deeper caries over pulp, outline form modification, internal design modification

Remove unsupported enamel, smooth, round, no acute angles

Question 2

Restoration retention function
Restoration resistance function (2)
Definition of configuration factor
Low configuration factor causes

Answer 2

Prevent restoration being dislodged
Meet forces of occlusion and prevent restoration being dislodged

Ratio of bonded to unbonded surfaces
Low polymerisation contraction stress

Question 3

Advantages of composite (2)
Disadvantages of composite (2)

Definition of hybrid layer

Why is bonding to deeper dentine difficult (2)

Definition of dead tracts

Answer 3

Good aesthetics, conserves healthy tooth tissue
Polymerisation contraction, reduced marginal integrity

Interface between dentine and composite

Deeper dentine is wetter and has more tubules - less surface area for hybrid bonding

Highly mineralised ends of dentinal tubules which block odontoblast processes, making them impermeable

Question 4

Definition of inlay
Definition of only

Advantage of indirect restorations
Disadvantages of indirect restorations (2)

Advantages (3) and disadvantages (3) of gold
Gold use

Advantage of indirect ceromeric
Advantages of indirect ceramic (4)
Types of indirect ceramic (3)
Indirect ceramic use - inlays or onlays

Advantages of CAD-CAM (2)
Disadvantage of CAD-CAM
Features of aesthetic tooth preparation (4)

Answer 4

Occlusal partially/fully intracoronal indirect restoration
Partially/fully intracoronal indirect restoration covering one/more functional cusps

Avoids technical errors (secondary polymerisation)
More destructive cavity preparation, provisional restoration required

Durable, strong, long-lasting; expensive, poor aesthetics, skill required (demanding tooth preparation)
For small lesions —> complete coronary breakdown

Good aesthetics
High strength porcelain, best aesthetics, less marginal leakage, better wear resistance
Onlays

Excellent marginal fit, no provisional restoration required
Tooth preparation is critical

No bevels, minimal axial wall taper, smooth, rounded

Question 5

Features of addition silicones (3)
Features of polyethers (4)

Disadvantage of stick trays

Components of gingival management (3)

Problems with impression taking (2)

Answer 5

Hydrophobic, difficult to pour, but adequate tear resistance
Addition type reaction, adequate tear resistance, hydrophilic, high rigidity when set

Perforations reduce hydrostatic pressure of impression material

Moisture control, haemostats and exude control, retraction, removal of excess tissue

Poor material/tooth bond, lack of occlusal details

Question 6

Definition of D1 caries
Definition of D2 caries
Definition of D3 caries

Definition of affected dentine
Definition of infected dentine

Principles of caries removal (3)
Reasons to removal carious tissue (2)

Types of caries removal with descriptions (3)

Answer 6

Enamel caries
Enamel caries with cavitation
Caries into dentine

Demineralised, soft dentine with no bacterial contamination
Demineralised, soft dentine with bacterial contamination

Preserve healthy and remineralisable tissue, maintain pulpal health, maximise restoration success

Create conditions for long-lasting restorations and to stop/reduce caries progress

Self-cleansing (optimal, poor aesthetics), partial caries removal (normal - consider RMGI liner, composite, one visit, 96% 3yr vitality) and stepwise caries removal (RMGI liner, GIC temporary restoration to allow tertiary dentine formation and hardening, composite permanent, 86% 3yr vitality)

Stepwise/partial caries removal have equal failure rates