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Yr 2 - OSCE & e-assessments > Operative and endo > Flashcards

Operative and endo Flashcards

1
Q

What is a crown?

A

A restoration that encompasses coronal tooth tissue, covering remaining tooth substance and restorations

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2
Q

Why do we place crowns?

A
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3
Q

What pressure is exerted when cutting at low speed?

A

2-5 lb

n.b. speed is inversely proportional to the pressure

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4
Q

What pressur eis exerted when cutting at higher speed?

A

1 lb

n.b. speed is inversely proportional to the pressure

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5
Q

What pressure is exerted when cutting at ultra high speed?

A

1-4 oz

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6
Q

What increases heat production of a treatment?

A

RPM of instrument

Amount of pressure applied by operator

Area of tooth in contact with the tool

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7
Q

What happens to the pulp at 113 degrees F?

A

Inflammatory respinse of pulp = Pulpitis

(n.b. this is reversible)

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8
Q

What happens to the pulp at 130 degrees F?

A

Permanent damage to the pulp

= pulpal necrosis

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9
Q

What are the uses of rotary cutting instruments?

A
  • Intra-coronal tooth preparation
  • Excavation of caries
  • Finishing cavity walls
  • Finishing restorations
  • Polishing restorations
  • Removing old restorations
  • Extra-coronal tooth preparation
  • Separating crowns and bridges
  • Adjusting acrylic prostheses
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10
Q

What are the 2 different designs of low speed handpieces?

A

Straight/contrangle

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11
Q

What is the speed range for a slow handpiece?

A

10,000 to 30,000 rpm

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12
Q

Which direction do slow handpieces turn?

A

Either clockwise (forward) or anticlockwise (backward)

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13
Q

What are the clinical uses for slow handpieces (5)?

A
  • Cleaning teeth
  • Caries excavation
  • Finishing and polishing procedures
  • Adjustment of porcelein
  • Root canal treatment
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14
Q

What are the lab uses for slow handpiece?

A

Trimming and adjusting of:

Temp crowns

Removable prostheses

Orthodontic appliances

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15
Q

What are the (2) advantages of low speed handpieces?

A

Better tactile sensation

Less chance of overheating cut surface

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16
Q

What are the (7) disadvantages of low speed handpieces?

A
  • Ineffective compared to high speed
  • Time consuming
  • Need to apply more pressure
  • Vibrations (uncomfortable for patient)
  • Slower cavity prep (increased operator fatigue)
  • Burs have tendency to roll out of preperation
  • Carbide burs = brittle = break at slow speed
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17
Q

What are the uses of high speed handpieces?

A

Tooth prep & removal of old restorations

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18
Q

What are the (3) advanatges of high speed handpieces?

A
  • Faster
  • Less pressure, vibration and heat needed
  • Less operator fatigue
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19
Q

What are the (3) disadvantages of fast handpieces?

A
  • Increased temp (without water)
  • Less tactile sense (overcutting possible due to water spray)
  • Air & water spray impair visibility
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20
Q

What speed do high speed handpieces go?

A

450,000 to 500,000 rpm

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21
Q

What are the 3 basic parts of rotary instruments?

A

Shank = fits into handpiece (friction grip/ latch grip)

Neck = connects shank to head

Head - cuts/finishes/polishes

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22
Q

Where do you dispose of fractured/blunt burs?

A

Sharps bin

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23
Q

What happens to caries hen it reaches the enamel-dentine junction (EDJ)?

Why?

A

It spreads laterally and deep into dentine

This is because….

Dentine has a lower inorganice mineral content than enamel = softer

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24
Q

In a carious lesion that extends up to half way between the EDJ and the pulp will the superficial dentine caries be hard or soft?

A

Soft

it will also correspond to the zone of destruction (bacterial invasion) histologically

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25
Q

As a carious lesion in the dentine becomes deeper what happens to its consistency and which areas will it correspond with histologically?

A

Harder

Regions of demineralisation without bacterail invnsion

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26
Q

What is the consistency of extensive, deep carious lesions which approach the pulp?

A

They will often be soft throughout

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27
Q

How do we remove caries?

A
  1. Gain access using 544 bur to cut through enamel (may be omitted where there is an open cavity and the caries can be seen directly) -> should be large enough so that caries at the EDJ can be seen and removed adequately
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28
Q

What difference can be noted when a 544 bur on a air turbine handpiece comes into contact with caries?

A

Sound changes

Bur doesn’t really move (just sinks in because its soft!)

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29
Q

What is the length of the cutting head of the 544 bur?

A

3mm

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30
Q

What do arrested caries feel like?

A

stained

hard/firmer -> due to remineralisation

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31
Q

How far into the tooth do you first come into contact with dentine caries?

A

Approx. 2mm

(2/3-3/4 of 544 bur depth)

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32
Q

In which direction should the slow (motor) handpiece be moving to make caries removal easier?

A

Clockwise

n.b. On the handpiece:

F = forward (clockwise)

R = reverse (anti-clockwise)

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33
Q

Which (3) instruments can we use to detect adequate removal of caries?

A

No. 18 probe

(listen - scrape = enamel, no sound = caries)

Excavators = Discoid or spoon

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34
Q

Which senses do we use to determine if caries has been removed?

A

Sight

Tactile (touch)

Sound (scraping)

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35
Q

Which instruments best remove caries?

A

Rosehead burs (problem will stil cut healthy enamel and dentine)

Excavator (preferrable near pulp because wont remove hard tissue)

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36
Q

What is the cavo-surface angle?

What is the ideal cavo-surface angle?

A

90 +/- 20 degrees

= 70-110 degrees

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37
Q

Which cusp is functional in the upper molars and premolars?

A

Palatal cusp

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38
Q

Which cusp is functional in the lower molars and premolars?

A

Buccal

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39
Q

What are the 3 different marginal finishes for crown preps?

A
  • Knife edge
  • Champfer
  • Shoulder
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40
Q

What is a knife edge finishing line?

A

Approx 180 degrees

= difficult to see & casting may be distorted during finishing

but close adaptation to the tooth surface

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41
Q

What is a butt joint/shoulder finish?

A

Approx 90 degrees

= seen clearly, not distorted by casting

= GOLD ALLOY DOES NOT CAST WELL TO IT!

42
Q

What is a chamfer finish?

A

Approx 135 degrees

= good compromise between knife edge and shoulder

= seen readily and resists distortion

= reasonable adaptation to the finish line at the tooth margin

Depth = approx 1/2 bur width (0.7mm)

43
Q

What is Supra-gingival?

A

Above the gingival margin

44
Q

What is sub-gingival?

A

Below the gingival margin

45
Q

What is equagingival?

A

Within the gum level (uses a retraction cord to push the gum away)

This is used more for anterior crown preparations

46
Q

What are the (2) disadvantages of getting lining on the walls of a cavity?

A
  • With time the lining will dissolve = microscopic gap between filling an tooth = microleakage & secondary caries
  • Important not to eliminate any undecuts needed for retention of the filling material
47
Q

When excess amalgam is safely disposed which four things should it be kept under?

A

Water

OR

Old x-ray fixer

OR

Potassium permanganate solution

OR

A container with a ‘vapour lock chemical’

48
Q

What is the problem with having extra holes in a rubber dam?

A

Seepage of saliva and materials through the dam

49
Q

What is the problem with having inappropriate positioning of holes in a rubber dam?

A

Seepage due to overstretching of the dam

50
Q

Discuss good and bad points of operator posture

A
51
Q

What is the normal focussing distance of the dental light?

A

30cm

52
Q

Why should the light not be too close to the patients mouth?

A

Impede operator access

Transmit too much heat to patient

Loose effective lighting in middle of field (black square)

53
Q

In which two ways can light be used?

A

Directly

Reflected onto work surface using mouth mirror

54
Q

Which two materials may be used to line a composite restoration?

A

A setting calcium hydroxide cement

Light cured GIC

55
Q

Why should Eugenol containing aterials never be used to line a composite restoration?

A

The eugenol would plasticise the resin base

56
Q

What is the consequence of over-etching the dentine?

A

Pulpal inflammation and pain

57
Q

Which wavelength of light is used to cure composites?

A

470nm

58
Q

What is the maximum depth for an increment in a composite restoration?

A

3mm (2mm to be on the safe side!)

59
Q

What is Oblique incremental curing?
And what does it avoid?

A

Building up a composite in 2mm increments

Avoids tension on a cavity = shrinkage at the margins = microleakage

60
Q

What possible problem has recent research indicated following light curing of composite resin?

A

Damaging temperature rises of the pulp

61
Q

What is the benefit of using a teflon coated instrument for composite?

A

Composite resin does not adhere so greatly to the instrument

62
Q

At what stage can we start to see occlusal caries on a bitewing xray?

A

When it has gone into dentine

63
Q

When is a class II cavity required?

A
64
Q

What does close adaptation of an amalgam fillin minimise (3)?

A
  1. Marginal leakage
  2. Secondary caries
  3. Post-operative sensitivity
65
Q

Compared to adjacent teeth what level do marginal ridges normally lie?

A

Similar level

(unless teeth are tilted following extraction of a tooth more mesial in the quadrant or if the tooth has over-erupted after the loss of an opposing tooth)

66
Q

What are the advantages of pre-wedging (2)?

A

Protects the rubber dam from damage by the bur

Increases the space between the teeth before the restoration (can overbuild contact = tighter meeting after the restoration has been placed and the wedge removed)

67
Q

Why can we not use a matrix band for Class II composite restorations?

A

We cannot condense composite = would not have as good a finish

68
Q

In which two ways can we protect adjacent teeth from damage when drilling a class II cavity?

A
  • Apply a matrix band (only protects from light damage with the bur)
  • Carefully removing the tooth structure att he contact point without rotary instruments (fracture out the surface with fgingival margin trimmer) = best way
69
Q

When is a matrix required?

A

To contain the restorative material in the area where there is a missing wall of tooth

70
Q

What is Xeno?

A

A self etching primer

71
Q

How does a self-etching primer work?

A

The acid etches the enamel = releases Ca ions = chelates the acid = neutralised and no longer etches

72
Q

Which solvent does Xeno contain?

A

Butanol

73
Q

What properties does primer have when its solvent is butanol?

A

Longer working time than other materials (that has acetone as a solvent = more volatile)

74
Q

What happens to the shade of teeth as they dry out?

A

Lighten

75
Q

What is Ceram X mono?

A

A nano-hybrid comosite resin

= variety of filler particle sizes = varies from 5nm to 7 microns

= heavily filled (= strong, wear resistance, minimal polymerisation shrinkage = 1% by volume)

76
Q

Why should the oblique layer of a composite restoration not contact the buccal and lingual walls of a cavity simultaneously?

A

Shrinkage when set = pulls the two wall of the cavity towards each other = cuspal bending (fracture risk)

77
Q

What is needed to diagnose fissure caries (4)?

A

Inspection of clean dry tooth surface

Sharp eyes (magnification)

Quality radiograph (only sometimes useful)

Probe to remove plaque from fissures

78
Q

Which types of caries are radiographs useful to exclude?

A

Occult caries (large dentine lesions underlying seemingly intact enamel only)

n.b. Enamel over cusps is too thick to see caries through and uneven enamel thickness makes it difficult to see any

79
Q

Why do we use hand instruments such as excavators to remove caries from the pulpal floor of a cavity?

A

Slow speed handpieces remove even sound dentine whereas handinstruments only remove carious dentine

= if too much dentine removed = exposed pulp :(

80
Q

What are the advantages of a GIC liner (3)?

A

Adhering to the dentine floor

Releasing fluoride

Bonds to overlying resin

81
Q

Why is it important not to look directly into a light curing light?

A

Damages the retina

82
Q

When light curing from the buccal side of the tooth in which direction does composite shrink?

A

Towards the buccal side of the tooth

83
Q

What is pit and fissure sealant composed of?

A

Unfilled Organic resin (UDMA/Bis-GMA + Dilutent resin e.g. TEGMA)

84
Q

Why can’t you wear rubber gloves when mixing putty?

A

Rubber plasticizers may inhibit the set

85
Q

What are the 5 principles governing preparation of a tooth for a crown?

A
  1. Preservation of tooth structure
  2. Retention and resistance form
  3. Structural durability of the restoration
  4. Marginal integrity
  5. Preservation of the periodontium
86
Q

What is retention?

A

The ability of the preparation to prevent removal of the restoration along its path of insertion

87
Q

What is resistance?

A

The ability of the preparation to prevent dislodgement of the restoration by forces directed in an apical, oblique or functional direction with lateral forces

88
Q

Why can we not do untapered preparation walls for crowns?

A

Need to avoid undercuts & allow for complete seating of the restoration during cementation

89
Q

What is the optimum taper for a crown?

A

5 to 8 degrees

(n.b. a taper of up to 16 degrees has been proposed as being clinically achievable while affording adequate retention)

90
Q

How can you ensure that you have removed the right amount of tissue?

A

Silicone index (i.e. impression of tooth before & cut in half)

Depth marker burs

91
Q

Where should the upper edge of the rubber dam fall (in single tooth isolation)?

A

Just above or below the nose

92
Q

When punching a hole in a rubber dam for a single tooth isolation where should it be placed?

A

Near the centre of the sheet (adjusted to fall in the appropriate quadrant i.e. for upper left would punch the hole slightly to the upper left side of centre)

93
Q

When isolating multiple teeth with a rubber dam, where should the stamp be placed?

A

Upper edge of stamp should be 1.5 cm below the upper border of the rubber dam

94
Q

Which 3 things determines the size of holes needed to be punched in a rubber dam?

A

The cervical diameter of the tooth (bigger tooth = bigger hole)

The elasticity of the rubber dam (heavier grades = less elastic = need larger hole)

The method of rubber dam application

95
Q

What can happen if the hole punched in a rubber dam is too small?

A

The dam can split

96
Q

What 3 things does a rubber dam napkin do?

A
  • Prevents marks on skin
  • Prevents moisture producing sores on the skin
  • Improves patient accepibility of the rubber dam
97
Q

When is single tooth isolation usually used?

A

Limited to endodontic treatment

98
Q

What is diagnosis?

A

The art and science that results from the synthesis of scientific knowledge, clinical experience, intuition and common sense

99
Q

What does a caries diagnosis imply?

A

Deciding whther a lesion is active, progressing rapidly or slowly or whether it is already arrested

100
Q

What (4) must be present for caries to develop?

A
  • Carbohydrate substrate
  • Susceptible tooth
  • Bacterial plaque
  • Time

Yr 2 - OSCE & e-assessments (7 decks)

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