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Operative > Class I and Class V Preparation Fundamentals > Flashcards

Class I and Class V Preparation Fundamentals Flashcards

1
Q

Dental Amalgam as a Restorative Material

A 
Amalgam is an alloy of silver, copper, 
tin, and zinc, mixed with mercury to 
form an alloy that can be packed into 
a dental preparation, and which will 
set up to form a solid restoration
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2
Q

skipped

properties of amalgam (5)

A
  1. High compressive strength and low tensile strength, which means it is brittle in small bulk.
  2. Sensitive to moisture contamination during placement. Water reacts with the zinc in the amalgam and causes an eventual expansion of the alloy out of the preparation.
  3. Amalgam is still a good choice in situations where moisture control is difficult. You can scrape off the top, contaminated layer and keep packing amalgam.
  4. Amalgam corrodes. Modern alloys
    have a high copper content which
    minimizes corrosion,but doesn’t
    prevent it entirely.
  5. Amalgam creates and regenerates a
    seal between itself and the tooth,
    because of the oxides formed—they
    expand and fill tiny voids and prevent
    microleakage. No other dental
    restorative material does this.
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3
Q

disadvantages of amalgam (6)

A
  1. Poor esthetics.
  2. Need for good “mercury” hygiene.
  3. Remove more tooth structure for adequate bulk of material.
  4. Doesn’t bond to tooth structure.
  5. Thermal conductor, necessitating use of a liner or base to prevent post-
    op sensitivity on deeper restorations.
  6. Eventually may “ditch” at the margins, collecting plaque in that area.
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4
Q

advantages of amalgam (6)

A
  1. More forgiving in areas where moisture is hard to control.
  2. High wear resistance and compressive strength.
  3. Can be placed in less time than other options (lower cost.)
  4. Relatively long-lasting.
  5. Regenerates its seal.
  6. Is less prone to recurrent decay than bonded composite resin
    restorations.
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5
Q

skipped

indications for amalgam (8)

A
  1. Moderate to large Class I and Class II restorations.
  2. Heavy occlusal wear.
  3. High caries rate.
  4. Difficult isolation.
  5. Gingival margins on root.
  6. Class V restorations in non-esthetic zones.
  7. Temporary restorations on teeth with questionable prognosis.
  8. Buildups under crowns for extensively damaged teeth usually with supplemental retention (pins, posts, grooves)
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6
Q

principles of tooth preparation for amalgam restorations:

have a means for

A

isolation of the site

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7
Q

have a means for isolation of the site (3)

A
  1. visibility
  2. access
  3. moisture control (especially important when restoring)
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8
Q

isolation materials (4)

A

rubber dam (gold standard)
cotton rolls
retraction cord
ISOVAC

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9
Q

all — — must be removed from all margins

A

undermined enamel

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10
Q

undermined enamel

A

enamel that is not supported by dentin under it

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11
Q

Margins should be – degrees at the

cavosurface on all axial surfaces

A

90

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12
Q

On the occlusal surface, margins may be
SLIGHTLY — in some areas, but must
NEVER BE — anywhere on the tooth

A

obtuse

acute

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13
Q

dentin must support all

A

surface enamel

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14
Q

Ideal preps are — into the dentin

A

0.2mm to 0.5 mm

  • Must prepare through the entire enamel layer.
  • This is determined by caries in a live patient.
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15
Q

This will mean different — in different places on the tooth. It will depend on the — of the enamel in the
area

A

depths

thickness

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16
Q

The traditional teaching about the OUTLINE FORM of an amalgam preparation states that the preparation must not terminate in the bottom of a

A

FISSURED pit or groove

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17
Q

On class II amalgams, contact is broken (2)

A

facially and lingually

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18
Q

extension for prevention

A

Preparations should encompass all carious and badly demineralized areas

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19
Q

retention form

A

what holds a restoration in a tooth (RETAINS the restoration)

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20
Q

do amalgams bond to tooth structure?

A

no

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21
Q

Smaller amalgams are held in by (2)

A

converging walls and/or by retention grooves if no walls can converge

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22
Q

These are elements in the design of a tooth preparation that will help
both restoration and tooth resist

A

fracturing

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23
Q

Maintaining as much tooth structure as possible. This makes the TOOTH
less likely to

A

fracture

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24
Q

Having some areas on the floor of a multi-surface preparation that are
— to occlusal forces make the restoration less likely to
fracture

A

perpendicular

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25
Q

Rounding — on a preparation (at least a little bit) make

the TOOTH less likely to fracture.

A

internal line angles

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26
Q

Smoothly rounding — forms make the RESTORATION less likely to
fracture.

A

outline

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27
Q

Preparing to — — prevents weakness (resists fracture) in the restoration

A

proper depth

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28
Q

NEVER leave enamel on the

A

floor of a preparation

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29
Q

NEVER leave a partial-depth ledge on the

A

enamel wall of an occlusal preparation, like a class I amalgam

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30
Q

Avoid leaving — under an amalgam that is subject to occlusal stress. This could result in fracture of the restoration

A

sharp external line angles

• Ex. axial wall of Class II preparation

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31
Q

class 1 (3)
occurs in…
restores…

A 
• Occurs in occlusal 2/3 of molar 
tooth
• Restores a developmental pit
• NOT a Class V (despite being on 
axial surface)
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32
Q

skipped

Buccal Pit Preparation

A

Use the 330 bur to do the preparation. Its flutes are 1.5mm top-to-bottom,
so they are a gauge for the proper depth

  • The 330 is an inverted cone form, so it will naturally converge walls.
  • Tip it occlusally in the occlusal “apex” to avoid converging the wall there.
33
Q

WALLS AT THE TERMINAL ENDS OF
THE BUCCAL AND LINGUAL GROOVES
— 3 DEGREES

A

DIVERGE

34
Q 
WALLS IN THE ISTHMUS AREAS 
--- 3 DEGREES ON EACH 
SIDE OF THE PREPARATION.  
ISTHMUS WIDTH IS --- MM
MINIMUM.
A

CONVERGE

1 MM

35
Q

WALLS ADJACENT TO MARGINAL

RIDGES — 3 DEGREES.

A

DIVERGE

36
Q

— THE MESIAL OR DISTAL
WALL ADJACENT TO THE MARGINAL
RIDGE LEAVES — — FOR
THE RIDGE IN THIS AREA

A

DIVERGING

DENTIN SUPPORT

37
Q

OCCLUSAL AMALGAM DEPTH :

A

.2mm inside dentino-enamel junction

38
Q

MOLARS:
PREMOLARS:

A

2 MILLIMETERS

1.5 TO 2 MILLIMETERS

39
Q

CONVERGING THE WALL ADJACENT TO THE

MARGINAL RIDGE RISKS

A

DESTRUCTION OF THE DENTIN SUPPORT FOR THE MARGINAL RIDGE

40
Q

How to Avoid an Off-Axis Preparation:

A

ENTER TEETH PARALLEL TO THE LONG AXIS OF THE TOOTH CROWN

NOT THE PATIENT

41
Q 
BUR INCLINES MORE MESIALLY IN 
THE --- AND MORE DISTALLY 
IN THE --- THE FURTHER 
POSTERIORLY WE GO, DUE TO THE 
CURVE OF SPEE
A

MANDIBLE

MAXILLA

42
Q 
BUR INCLINES MORE LIGUALLY IN 
THE --- AND MORE 
BUCCALLY IN THE --- THE 
MORE POSTERIORLY WE GO, DUE 
TO THE CURVE OF WILSON
A

MANDIBLE

MAXILLA

43
Q

prep too shallow

prep too weak

A

still in enamel

close to pulp, weakens tooth

44
Q

Angular Outline Form Could Cause Areas of Stress Concentration In the Areas Marked Above in Red, —- Amalgam

A

Fracturing

45
Q

skipped
Analyze the Occlusion
Look for “Plunger Cusp” Situations (3)

A

Opposing cusps have
burrowed into old
restorations, creating
inclined plane contacts.

Shorten supporting cusps,
preserving correct cusp form.

Place new restorations,
elevating fossa bottoms
to restore contact in M.I.
(long axis forces restored).

46
Q

Enter the tooth with a — Bur

Keep bur parallel to the

A

169

Long Axis of the tooth (both mesiodistally and faciolingually)

47
Q

Insert your bur to a Depth of — mm. with the 169 bur.

A

1 ½

48
Q

Hold the bur — to the long axis of the tooth while preparing

A

perpendicular

49
Q

Keep the preparation as — as possible– just the width of the bur
Stop in the mesial and distal pits.

A

narrow

50
Q

The 169 bur will give a slightly — prep. in all areas, since it is a
tapered fissure bur.

A

divergent

51
Q

A 169 bur is a tapered — bur

A

fissure

52
Q

A 169 bur is a tapered fissure bur
◦ It will prepare a preparation with — walls if held in a single plane.
◦ It has sharp edges on its tip, and will leave sharp — line angles in the prep.
◦ Its flutes measure 4mm. top to bottom.
◦ Half the depth of the bur head would cut a – mm. deep prep.

A

diverging
internal
2

53
Q

At — mm. of depth on an
ordinary molar, the bur has
not penetrated into dentin

A

1.5

54
Q

Using a 245 bur, insert to a depth of — (Molar) or — (Premolar)

A

2mm

1.5mm

55
Q

A 245 bur is an inverted — bur, with

rounded edges on its flat end

A

cone

56
Q

A 245 bur is an inverted cone bur, with
rounded edges on its flat end.
• If held in one plane, it will cut an — prep. with — internal line angles.
• Its flutes measure — top to bottom, so half the depth of its head will cut a — prep. and 2/3 of its head will cut to a depth of —

A

undercut, rounded
3mm
1 ½mm
2mm

57
Q

Widen the isthmuses to 1mm, and converge their walls about

A

3◦ each

58
Q

Tip the 245 bur enough mesially &

distally to — the mesial & distal walls 3-4⁰. Blend from these walls into the — walls of the isthmuses

A

diverge

converging

59
Q

Diverge Walls at the Terminal Ends of Buccal and Lingual Grooves on Molars
Tip the 245 bur buccally or lingually to
— walls adjacent to the buccal
and lingual cusp ridges 3-4 ̊

A

diverge

60
Q

class V buccal amalgam preparation restores

A

caries on the gingival third of the buccal and lingual surfaces of teeth

61
Q

almost al caries starts —, but often spreads — onto the root surface

A

supragingivally

subgingivally

62
Q

GINGIVAL RETENTION GROOVE

A

THERE IS A COMPARABLE OCCLUSAL RETENTION GROOVE AT THE
OCCLUSAL-AXIAL LINE ANGLE. THEY ARE IN DENTIN, JUST INSIDE THE
D.-E. JUNCTION EVEN WHEN THE AXIAL WALL IS DEEP DUE TO CARIES

63
Q

Enamel in the cervical area is —

A

thinner

◦ preparation is not as deep as an occlusal amalgam

64
Q

Since the preparation is in a smooth area, outline form is determined by
the

A

extent of caries.

◦ Rather than following anatomy

65
Q

Since the prep. is in a convex surface and all amalgam margins must be
90◦,

A

all walls diverge

66
Q

grooves are needed for

A

retention

67
Q

The axial wall is — when caries is minimal

A

convex

68
Q

a Bucco-lingual longitudinal section

shows

A

retention grooves and divergent walls

69
Q

The entire thickness of the enamel is perpendicular to the — and is still supported internally by —

A

cavosurface

dentin

70
Q

Class V Buccal Amalgam Preparation: Procedure

A

• Use the 169 bur to prepare the tooth to a uniform depth
of 1.5 mm.
• Keep the long axis of the bur perpendicular to the
surface of the tooth. In an ideal preparation, the axial
wall should be convex.
• In a live patient, the outline form is determined by extent
of caries
• Initial entry is made with a #2 round bur on SLOW
SPEED, excavating caries.
• Then use the 169 bur at high speed used to refine
internal line angles and cavosurface margins.
• Only extend deeper than 1.5 mm where caries must be
removed.

71
Q

When caries extend on to root surface /subgingival the rules for depth may
change:
A. When there is minimum thickness of enamel: — depth.
B. When the margin is on the root: — depth.

A

1 mm

0.75 mm

72
Q

A ¼ round bur is used to place an occlusal and a gingival retention groove

A

entirely in dentin, just inside the DEJ

73
Q

On preps. with minimal axial depth, it will be necessary to bisect the (2)

A

occlusal axial and gingival axial line angles

74
Q

on deep preps, the grooves still go

A

just inside the DEJ

75
Q

when caries extends into the inter proximal embrasures

the problem:

A

the adjacent tooth blocks access for the side of a 169 bur

76
Q

skipped
when caries extends into the inter proximal embrasures
the solution: (3)

A

Excavate caries with #2 round bur

Use a gingival margin
trimmer to remove
undermined enamel
interproximally

Use the end of a
169 bur to define
internal line angles
interproximally

77
Q

Caries may cause — in some areas.

Don’t…

A

unequal axial depth

dont remove healthy tooth structure deeper than 1.5 mm. just to get
even axial depth

78
Q

Correct Way to Handle Deep Caries Situation:

A

Grooves Just Inside D.-E. Junction

Operative (11 decks)

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