Class II amalgam restorations

Question 1

Embrasure

Answer 1

V-shaped valleys between adjacent teeth

-provide spill way for food to escape during chewing which essentially aids in self-cleansing process

Question 2

Retention

Answer 2

Use pear-shaped bur

Undercut

Question 3

Manipulation and adaptation of amalgam

Answer 3

Good condensation / effective packing to ensure marginal seal

Question 4

What needs to be considered

Answer 4

Method of retention for material of choice
Prevention of recurrent caries - elimination of microleakage
Assist remineralisation of tooth tissue
Longevity under occlusal load - fracture and wear resistance
Protect tooth from mechanical failure
Aesthetics

Question 5

Class II

Answer 5

Lesions occurring between posterior teeth only

Size can vary from moderate involvement to bulk loss of tooth structure

Question 6

Direct restorative materials

Answer 6

Classified as plastic i.e. readily deformable when first mixed
Placed into prepared cavity whilst still in that condition
Modelled/ moulded into appropriate shape e.g. amalgam

Question 7

Class II cavity preps if interproximal

Answer 7

Have to drill all the way down through marginal ridge

Try to keep thin enamel at base

Question 8

Define D1, D2, D3, D4

Answer 8

D1: initial caries
D2: enamel caries
D3: caries of dentine
D4: pulpal involvement

Question 9

Isthmus

Answer 9

Central portion of cavity prep on the occlusal surface of a bicuspid or molar
You have cut it too wide
Try to keep it as narrow as possible

Question 10

Iatrogenic damage

Answer 10

Operator damage e.g. on adjacent tooth
Would fail exam
Must inform patient - candour
Avoid by using matrix band

Question 11

Axial grooves or locks

Answer 11

For added retention

Locks in dentine not enamel (enamel will shatter)

Question 12

Axial wall

Answer 12

Wall closest to pulp
Don’t cut too deep
Maybe put liner there to protect it

Question 13

Principles of cavity prep

Answer 13

Do not damage adjacent tooth
Access should be sufficient to allow adequate visualisation of caries and to allow complete removal
Prepare below contact point
Prepare just into embrasures so that margins are visible and can be finished well
Do not leave unsupported enamel at margins
Removal of caries at ADJ

Question 14

Wooden wedge

Answer 14

To separate contact point

-for adapting a matrix band to the proximal part of a cavity

Question 15

Ditching

Answer 15

Marginal breakdown

Question 16

Marginal ridge

Answer 16

Rounded borders that form the mesial and distal margins of the occlusal surface of a tooth
Meant to deflect food from fossa, stops food from getting trapped in contact area

Question 17

Indirect restorative materials

Answer 17

Materials usually formed in lab and finished restoration cemented into placed, e.g. Full Gold Crown

Question 18

Slot and box

Answer 18

1 - 1.5mm deep box like grooves prepared in dentine to > SA

Question 19

Occlusal lock

Answer 19

Dovetail

Question 20

Changing concepts

Answer 20

Improved amalgams
Instruments with v small working points
Amalgam bonding systems
Adhesive restorative materials
'If in doubt prevent' rather than 'if in doubt fill'

Question 21

Principles of cavity prep

Answer 21

Do not damage adjacent tooth
Access should be sufficient to allow adequate visualisation of caries and to allow complete removal
Prepare below contact point
Prepare just into embrasures so that margins are visible and can be finished well
Do not leave unsupported enamel at margins
Allow sufficient depth for amalgam, at least 2mm
Remove all caries from ADJ

Question 22

When to extend or not: if proximal lesion visible

Answer 22

If proximal lesion visible & access good then marginal ridge can be conserved

Question 23

When to extend or not: if proximal lesion is not visible, access is difficult or there is <2mm tooth structure below marginal ridge (occluso-gingivally)

Answer 23

Access through marginal ridge advised

This will produce a small box form sufficient to eliminate lesion

Question 24

When to extend or not: if tooth is caries free occlusally

Answer 24

NOT necessary to cut out the fissure

Question 25

Extension is a balance

Answer 25

Between conservation of tooth structure and need to remove defective tooth structure

Question 26

When to extend or not: where occlusal caries and/ or removal of an old restoration have required extending occlusally

Answer 26

An occlusal lock/ dovetail can be prepared to retain the approximal part of the restoration

Question 27

Where is initial cut made in Class II prep? What bur should be used?

Answer 27

Initial cut made through marginal ridge to penetrate caries and then widened bucco-lingually
Diamond pear shaped bur or tungsten carbide bur

Question 28

Proximal plate

Answer 28

Can be fractured off with a hand instrument to avoid damage to adjacent tooth (or can you use a matrix band)

Question 29

What would you remove the proximal wall with?

Answer 29

Gingival margin trimmer

Question 30

Most important place for caries to be removed from

Answer 30

ADJ

Question 31

What is the size of the cavity determined by?

Answer 31

Determined by size of carious lesion, extension beyond this should be minimal

Question 32

How is retention from occlusal forces derived?

Answer 32

From a 2-5 degree divergence of the walls towards floor in both parts of the prep

Question 33

Where should the margins of the box extend to

Answer 33

Just outside the contact area unless caries dictates otherwise

Question 34

Exception to box design

Answer 34

When using adhesive materials e.g. composite

Question 35

Principles of retention for amalgams

Answer 35

Relies on mechanical interlocks

A degree of adhesion can be developed through use of luting or bonding agents

Question 36

What type of restorative material is an amalgam classed as?

Answer 36

Direct plastic restorative material

Question 37

Cavo surface angle

Answer 37

Above 70 degrees, preferably 90 degrees to prevent ditching

Question 38

Accepted minimal dimensions for amalgam

Answer 38

2mm occlusally and 1mm - 1.5mm elsewhere i.e. proximal box

Sufficient bulk to prevent fracture, max thickness of dentine protecting bulk

Question 39

Deep preps

Answer 39

May require base or liner

Question 40

Proximal box area

Answer 40

Fractured margins need to be planed with gingival margin trimmer to remove fragile enamel prisms, which could break off and affect marginal seal

Question 41

Proximal box design amalgam

Answer 41

Retention grooves places B&L 0.5mm deep to ADJ (dentine) gingivally, fading away occlusally, rounded in cross section
Directed laterally not pulpally

Question 42

Extension onto occlusal surface

Answer 42

Prone to fracture at isthmus therefore sufficient depth must be provided here
Width of isthmus should not be over-cut
Axio-pulpal line angle should be rounded or bevelled to reduce risk of amalgam fracture

Question 43

Matrix bond and wedges

Answer 43

Avoid creation of overhang at cervical margin

Ensure good contact point with adjacent tooth

Question 44

Matrix systems purpose

Answer 44

Substitute for missing walls
Create contact point
Restrict extrusion of amalgam and formation of overhangs or ledges
Provide contour for proximal surface restoration
Allow adequate surface texture in areas inaccessible to burnishing

Question 45

Types of matrices

Answer 45

Siqveland
Tofflemire
Automatrix
Omnimatrix and luciwedges
'V' ring/ half band matrices

Question 46

Contour

Answer 46

Conves side of spoon excavator used to impart convex contour to matrix band
Achieve good contact area with adjacent tooth
Ensure dental floss placed below contact point to assist removal of ledges & excess amalgam

Question 47

Condensing amalgam

Answer 47

Using amalgam pluggers or condenser
Adaptation of amalgam to walls of prep
Eliminating voids
Incremental placement of 1mm thickness essential to ensure max condensation

Question 48

Carving

Answer 48

Wards carver e.g. No 2 or excavator

Marginal ridge should be carved, taking care not to over carve or miscarve

Question 49

Post carve burnishing

Answer 49

Light rubbing over surface of carved amalgam with burnisher

Do not use heavy forces, avoid margins

Question 50

If amalgam soft after carving

Answer 50

Wipe with cotton roll saturated in water to proved additional smoothing

Question 51

After burnishing

Answer 51

Check occlusion