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NBDE II > OPERATIVE Preparation of Teeth > Flashcards

OPERATIVE Preparation of Teeth Flashcards

1
Q

in the preparation of a tooth for a restoration, what are the objectives of mechanically altering the tooth to receive the appropriate restorative material?

A
  • maximum strength

- maximum form, function, and esthetics

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2
Q

what are the 5 objectives of tooth preparation?

A
  1. remove all defects
  2. protect the pulp
  3. be as conservative as possible
  4. make tooth and restoration strong
  5. make restoration functional and esthetic
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3
Q

what are the general factors affecting tooth preparation?

A

diagnosis, patient desires, multitreatment needs

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4
Q

what are the examples of conservation of tooth structure as it relates to tooth preparation?

A

supragingival margins, minimal pulpal depth, minimal faciolingual width, rounded internal line angles

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5
Q

what are the benefits of smaller preparations?

A

less removal of tooth structure, better esthetics, les trauma to pulp, stronger remaining tooth structure, more easily retained material

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6
Q

what are the biologic considerations for tooth preparations?

A

pulpal affects of preparation, fracture potential of undermined enamel, tooth strength considerations

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7
Q

what is the pulpal depth for an amalgam preparation?

A

uniform 1.5mm

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8
Q

what is the axial depth for an amalgam preparation?

A

uniform 0.2-0.5mm inside DEJ

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9
Q

what should the cavosurface margin of an amalgam vs composite preparation be?

A
  • amalgam should be 90 degrees

- composite should be greater than 90 degrees

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10
Q

what should the texture of prepared walls look like in amalgam vs composite preparations?

A
  • amalgam should be smoother (carbide burs)

- composite should be rough (diamond burs)

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11
Q

what is the primary retention form for amalgam vs composite preparations?

A
  • amalgam should have convergence occlusally

- composite does not have retention form (rely on roughness and bonding)

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12
Q

what is the secondary retention form for amalgam vs composite preparations?

A
  • amalgam should have grooves, slots, locks, pins, and/or bonding
  • composite should have bonding, and grooves for very large or root-surface preps
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13
Q

what increases resistance form for amalgam preparations?

A

amalgam should have flat floors, rounded angles, box-shaped floors, perpendicular or occlusal forces

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14
Q

what are the base indications for amalgam and composite preparations?

A
  • amalgam - provide 2mm between pulp and amalgam

- composite not needed

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15
Q

what are the liner indications for amalgam and composite preparations?

A

Ca(OH)2 over direct or indirect pulp caps in both preparations

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16
Q

what are the sealer indications for amalgam and composite preparations?

A
  • amalgam - gluma desensitizer when not bonding

- composite - sealed by bonding system used

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17
Q

what should initial (primary) tooth preparation include?

A

extension of the preparation walls to sound tooth structure in all directions except pulpally

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18
Q

what is the definition of outline form and initial depth?

A

extension to sound tooth structure at an initial depth of 0.2-0.75mm into dentin

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19
Q

what are the principles of outline form and initial depth?

A

place margins where finishable, remove unsupported and weakened tooth structure, include all faults

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20
Q

outline form and initial depth is dictated by what?

A

caries, old material, size of defect, occlusion, marginal configuration, and adjacent tooth or contour

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21
Q

what are the goals/features of outline form and initial depth?

A
  • preserve cuspal strength
  • preserve marginal ridge strength
  • keep faciolingual width narrow
  • connect two close (0.5mm) preparations
  • restrict depth to 0.2-0.75mm into dentin
  • use enameloplasty
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22
Q

what are the features of outline form and initial depth of occlusal preparations?

A
  • extend margin to sound tooth structure
  • extend to include all of the fissure that is not eliminated by enameloplasty
  • restrict depth to 0.2mm into dentin
  • join two preparations if less than 0.5mm remaining
  • extend to provide access for preparing, inserting material, and finishing the restoration
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23
Q

what are the features of smooth-surface preparations with respect to proximal surfaces?

A
  • extend until no friable enamel remains
  • do not stop margins on cusp heights or ridge crests
  • get enough access
  • axial wall depth restricted to 0.2mm inside DEJ to 0.75mm depth from external surface
  • extend gingival margin to get 0.5mm clearance
  • extend facial and lingual proximal walls to clearance; extend 1mm or more to break contact arbitrarily if necessary
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24
Q

outlines of gingival walls of class V preparations are governed only by ___

A

extent of the lesion except pulpally

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25
Q

enameloplasty is the removal of a defect by recontouring or reshaping the enamel when the defect is no deeper than ___

A
  • 1/4 the thickness of the enamel

- if the defect is greater than 1/3 the thickness of enamel, then the wall must be extended

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26
Q

___ form is the prevention of tooth or restoration fracture from occlusal forces along the long axis of the tooth

A

primary resistance form

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27
Q

what are the 3 factors that affect primary resistance form?

A

occlusal contacts, amount of remaining tooth structure, type of restorative material

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28
Q

what are the features of primary resistance form?

A
  • flat floors, pulpal and gingival
  • box shape
  • preserve marginal ridges
  • preserve cuspal strength
  • remove weakened tooth structure
  • cap cusps as indicated
  • rounded internal line angles
  • adequate thickness of material
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29
Q

___ form is the prevention of dislodgment of restorative material

A

primary retention form

30
Q

what are the features of primary retention form?

A

preparation wall configuration - shape, height, form

31
Q

___ form is alterations to improve access and visibility for preparing and restoring the cavity

A

convenience form

32
Q

what components are involved in final tooth preparation?

A
  1. removing remaining caries
  2. deep excavation, questionable dentin near pulp (indication for indirect pulp cap)
  3. pulpal communication (exposure) - indications for direct pulp cap
  4. endodontic treatment
33
Q

when removing remaining caries in the final tooth preparation, how should deep excavation be handled?

A
  • leave the last bit of leathery carious dentin, place reinforced glass-ionomer as caries-control restoration
  • may or may not use calcium hydroxide liner
  • may or may not reenter to reexcavate after 6-8 weeks (evidence is controversial)
  • after follow up period (6-8 weeks), restore with definitive restoration
34
Q

when removing remaining caries in the final tooth preparation, how should pulpal communication (exposure) be handled?

A
  • isolate area
  • control hemorrhage
  • use calcium hydroxide for reparative dentin
  • place RMGI base over liner
  • remove coronal portion of exposed pupal tissue in pulp chamber, and place calcium hydroxide liner and RMGI base
35
Q

what are the indications for a direct pulp cap?

A
  • small mechanical (noncarious) exposure <1mm

- asymptomatic tooth

36
Q

what are the indications for endodontic treatment when removing remaining caries in the final tooth preparation?

A
  • large and carious exposure >1mm
  • symptomatic tooth
  • area contaminated (saliva, debris)
  • purulent exudate
37
Q

secondary resistance and retention forms may be performed after placement of ___

A

liners and bases

38
Q

___ establishes the design and smoothness of the cavosurface margins

A

finishing external walls

39
Q

what are the objectives of finishing external walls?

A
  • best seal between tooth and material
  • smooth junction between tooth and material
  • maximum strength for tooth and material
40
Q

what are the two features of finishing external walls?

A

bevels and butt joints

41
Q

what are the considerations in finishing external walls?

A

direction of enamel rods, support of enamel rods, type of material, location of margin, and degree of smoothness desired

42
Q

what are the features of final procedures of tooth preparation?

A
  • cleaning, inspecting, sealing, and applying surface treatments
  • readying the preparation for the material
  • removing any debris
  • sealing or bonding
43
Q

what are the goals of isolation in the operating field?

A
  • moisture control
  • retraction and access
  • harm prevention
44
Q

moisture control refers to excluding ___, ___, and ___ from the operating field. it also refers to preventing ___ and ___ from being swallowed or aspirated by the patient

A
  • sulcular fluid, saliva, and gingival bleeding

- handpiece spray and restorative debris/materials

45
Q

what 3 things aid in moisture control?

A
  • rubber dam, suction devices, and absorbents

- local anesthetics also play a role in controlling moisture in addition to eliminating discomfort

46
Q

what are the advantages of the rubber dam?

A

increased access and visibility, isolation, keeps area dry, protects patient and operator, retracts soft tissue, preserves and protects materials

47
Q

what are the disadvantages of the rubber dam?

A

some patients object, some situations do not work, partially erupted teeth, extremely malpositioned teeth

48
Q

in conjunction with ___, absorbents provide acceptable moisture control for most clinical procedures

A

profound anesthesia

49
Q

what are cellulose wafers?

A

absorbants used for moisture control and isolation

50
Q

in amalgam preparations, the initial depth pulpally is ___mm inside the DEJ or ___m as measured from the depth of the central groove - whichever results in the greatest thickness of amalgam

A

0.2mm, 1.5mm

51
Q

in amalgam preparations, the initial depth of the axial wall form is ___mm inside the DEJ when retention locks are not used, and ___mm inside the DEJ when retention locks are used

A

0.2mm, 0.5mm

the deeper extension allows placement of the retention locks without undermining marginal enamel

52
Q

in amalgam preparations, if the axial wall extends onto root surface, how deep should it be and why?

A

0.75-1mm to provide room for a retention groove or cove, while providing for adequate thickness of the amalgam

53
Q

when cutting any preparation, it is important to remember that for enamel strength, the marginal enamel rods should be supported by ___

A

sound dentin

54
Q

when making preparation extensions, every effort should be made to preserve the strength of the ___ and ___

A
  • cusps and marginal ridges
  • when possible, outline form should be extended around cusps and avoid undermining the dentinal support of the marginal ridge enamel
55
Q

when viewed from the occlusal, the facial and lingual proximal margins of a class II amalgam preparation should be ___ degrees

A
  • 90 degrees

- in most instances, the facial and lingual proximal walls should be extended just into the facial or lingual embrasure

56
Q

in class II amalgam preparations, why is it necessary to extend facial and lingual proximal walls just into the facial/lingual embrasures?

A
  • provides adequate access for performing the preparation
  • easier placement of matrix band
  • easier condensation and carving of the amalgam
  • provides clearance between the cavosurface margin and adjacent tooth
  • this extension is always necessary
57
Q

what are factors that dictate outline form?

A

caries, old restorative material, inclusion of the entire defect, proximal or occlusal contact relationship, and need for convenience form

58
Q

if either enamel or amalgam has marginal angles less than 90 degrees, they are subject to ___

A

fracture because both are brittle structures

59
Q

what provides amalgam retention form?

A
  • mechanical locking
  • preparation of vertical walls (especially facial and lingual) that converge occlusally
  • locks, grooves, coves, slots, pins, steps, or amalgam pins
60
Q

what provides amalgam resistance form?

A
  • preserve cusps and marginal ridges
  • prepare pulpal and gingival walls perpendicular to occlusal forces
  • rounded internal preparation angles
  • no unsupported or weakened tooth structure
  • placing pins into the tooth as part of the final stage of tooth preparation (considered secondary resistance feature)
61
Q

what are the resistance form features that assist in preventing the amalgam from fracturing?

A
  • adequate amalgam thickness (1.5-2mm in areas of occlusal contact and 0.75mm in axial areas)
  • marginal amalgam of 90 degrees or greater
  • boxlike preparation form
  • rounded axiopulpal line angles in class II tooth preparations
62
Q

many amalgam preparation resistance features can be achieved using which bur?

A

245 carbide (inverted cone with rounded corners)

63
Q

many features that enhance retention form also enhance ___

A

resistance form

64
Q

usually the larger the tooth preparation, the greater the need for ___

A

secondary resistance and retention forms

65
Q

what are the preliminary considerations for composite preparations?

A
  • occlusal assessment of both operated and adjacent teeth
  • clean tooth with flour of pumice (only if no tooth preparation is done)
  • shade selection before teeth are dried
  • area isolation
66
Q

for composite preparations, minimal mechanical retention is needed except in which cases?

A
  • no enamel (root surface, need more retention)

- large restoration (need more retention)

67
Q

what is the purpose of roughening enamel in composite preparations?

A
  • increased surface area = increased retention
  • use a coarse diamond
  • can also place a bevel, only on facial visible margins (usually 0.5mm wide and at 45 degrees)
68
Q

in composite preparations, floors should be prepared perpendicular to the long axis of the tooth when concerned about ___ or if ___

A
  • resistance form

- preparation is large

69
Q

what are 4 new approaches for preparations (controversial)?

A
  • box only preparations
  • tunnel preparations (not recommended)
  • sandwich technique
  • bonding a weakened tooth
70
Q

what is the idea behind bonding a weakened tooth?

A

-features (arbitrary extension of grooves or walls, arbitrarily leaving weakened tooth structure) may help in increasing the strength of the remaining weakened tooth structure because of the micromechanical bond of the material reinforcing the tooth

NBDE II (35 decks)

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