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Flashcards in Fixed Final Deck (123):
1

Biological Contours

Stimulate natural healthy teeth

Protect the supporting tissues

Maintain the health of Gingiva and periodontum

Minimize trauma and irritation to bony tissues

2

Improper contours

Often induce early breakdown of supportive structures

Result in early loss of teeth

3

Biological contour checklist

Facial and lingual convexities
Mesial and distal concavities
Transitional line
Contact area and embrasures
Cervical curvatures
Marginal ridges
Tooth Reduction

4

The greatest convexity on the axial surface of the crown

Height of contour

5

The contours of a tooth are

Curved

6

When viewed from mesial or distal aspects crowns have a rather uninformed curvatures in the

Cervical third and middle third

7

The proper degree of curvature will

Deflect food over the gingival margin preventing irritation

And stimulation of soft tissues

8

If curvature is absent the ginigival tissue will be

Driven apically and this will result in pathological changes

9

If the curvature is too great

The Gingiva is protected too much and loses gingival to one

Food and debris may pack under this area and result in chronic inflammation of the Gingiva

10

Facial contours

No more than 1/2 mm facially beyond the CEJ

Height of contour is in the cervical third

11

Lingual Contours

No more than 1/2 mm lingually beyond the CEJ

Height of contour is in the middle third

12

Lingual contour exceptions

Mandibular second premolar and molars

3/4-1mm lingual

13

Emergence Profile

Tooth surface that is gingival to height of contour and above the gingival crest

-the profile of the gingival third of a restoration as it emerges from the gingival crevice

14

The emergence profile should be

Flat for 2-3 mm above the Gingiva

15

Proximal surfaces are always ____ or slightly _____ between the contact area and the CEJ to allow room for the _____

Flat
Concave
Papillae

16

Contact Area

The area of mesial or distal surface of a tooth which touches its neighbors

It is similar to a ball to ball contact

17

Basic Functions of Contact Area

AIDS in proper development of the arches

Prevents food from packing between the teeth

Allows the teeth to be self cleaning

Prevents injury to the interproximal tissues

18

What happens to contact areas with age

The contacts get broader with time due to wear as the teeth move during function

19

Contact areas of all posterior teeth should be

Buccal to the central fossa and in the occlusal third

20

Posterior teeth contact areas are in the occlusal 1/3 except what teeth

Between maxillary molars-junction of occlusal and middle 1/3 or middle 1/3

21

Posterior teeth contact areas are buccal to buccolingual center except what teeth

Between maxillary molars

Middle 1/3

22

Distal contacts are more

Cervical than mesial contact

23

Distal contacts are more cervical than mesial except

Mandibular first premolars

24

Proximal contacts aid in

Arch integrity

Prevent food retention

Protect interdental papillae

25

Transitional Line Angles

Between the faciolingula convexities and proximal concavitiies there is a surface call the transitional line

26

The contours of the transitional line angle should

Blend the convexities and concavitiies without excess bulk or irregularity

27

Improper contours present a hazard to

The supporting tissues

28

Transitional line angles are straight between the _______ and _______

The proximal contact point and the cenmentoenamel junction

29

Marginal Ridges

On the occlusal surfaces at the proximal border there is a ridge like structure neihbored by two depressions

-one depression is the occlusal embraces
-The other is the proximal fossa

30

Marginal ridges are ____ MD and ____FL

Convex MD

Concave FL

31

Adjacent marginal ridges are the same height except

Between canines and premolars

32

Marginal ridges converge from buccal to lingual

Facial is 1/2 wider than lingual

33

Marginal ridges converge from buccal to lingual except

Mandibular 2nd premolar 3 cusp type

Maxillary first molar

34

Spillway space

Embrasure

35

Functions of embrasure

The spillway for the escape of food during function

It helps keep the tooth clean

36

Which embrasure is always large

Lingual is always larger than buccal

37

Lingual embrasure is always larger except

?

30?

38

Cervical curvature relates to

The contour of the bony alveolar area

39

Biological width

1.5 to 2mm

40

Biological width includes

Both connective tissue attachment and junctional epithelium

41

3 principals of tooth preparation

Biologic Considerations

Mechanical Considerations

Esthetic Considerations

42

Biologic Considerations

Affect the health of the oral tissues

Prevention of damage during tooth preparation
-soft tissue
-Pulp
-Adjacent teeth

43

Mechanical Consideration s

Providing Resistance Form

Providing Retention Form

Preventing Deformation of the restoration

44

Providing resistance form

Magnitude and direction fo the dislodging forces

Geometry of the tooth preparation

Physical properties of the outing agent

45

Providing Retention Form

Magnitude of the dislodging forces

Geometry of the tooth preparation

Roughness of the fitting surface of the restoration

Materials being cemented

Film thickness of the luting agent

46

Preventing Deformation of the restoration

Alloy selection

Adequate Tooth reduction

Margin design

47

Indications for a single crown

Extensive coronal destruction

Shorts clinical crowns

Endo treated teeth

Maximum retention and resistance are needed

Correction of axial contours

48

Contraindications for single crown

Wherever an intact buccal or lingual wall exists

If less than maximum retention and resistance are needed

If objectetives can be met with a more conservative restoration

49

All axial surfaces of the tooth are included in the preparation the complete cast crown

has greater retention than a more conservative restoration

50


Single crown has_______ form than a partial coverage restoration on the same tooth

Greater resistance

51


A complete crown allows the operator to modify

Axial tooth contour as well as occlusal modification

52

Removal of tooth structure is extensive and can have

Adverse effects on the pulp and periodontist

Common to see gingival inflammation

53

After cementation it is no longer feasible to

Perform electric vitality testing of an abutment tooth

54

Crown disadvantages

Removal of large amount of tooth structure

Adverse effects on tissue

Display of metal

Vitality testing not feasible

55

Finish line

The terminal operation of the prepared tooth (tooth margin)

-Where prepared tooth meets unprepared tooth

56

Chamfer

A finish line design for tooth preparation in which the gingival aspects meets the external axial surface at an obtuse angle

57

Chamfer extends around

The most cervical portion of the tooth preparation

58

Axial Inclination

The alignment of the long axis of a tooth to a selected plane, often the horizontal plane

59

The long axis is determined clinically by bisecting the angle formed by opposing axial surfaces in the

Gingival third of the tooth

60

POW

The specific direction in which a prosthesis is place on the abutment tooth or remove from it

61

POW should coincide with

Long axis

62

Taper

The convergence of two opposing external walls of a tooth preparation

63

Ideal convergence angle

6 degrees

64

More the taper

Lesser the retention

65

CVC dimensions

Central groove 1mm
Functional Cups 1.5 mm
Nonfunction cusp 1 mm
Chamfer width .5 mm

66

Most noble and corrosion resistant metal

Gold

67

Gold is ____ and _____ metal

Ductile
Malleable

68

Gold dental restorations?

No too weak unless alloying elements are used

69

Gold is not tarnished by

Air, water

70

Gold does not dissolve in

HCL
H2SO4
HNO3

71

Gold can be etched by

Aqua regia

72

Do noble metals form stable oxides at room temperature

NO

73

What has the lowest tendency to lose elections and become positive ions

Noble metals

74

The noble metals

Gold
Platinum
Palladium
Iridium
Ruthenium
Rhodium
Osmium

75

Is silver a noble metal in oral environment?

NO

76

Precious metals classification is based on

Price not electrochemistry

77

Relatively common and inexpensive metals become precious when

Very high purity is required

78

Alloy Selection Factors

Cost of the metal

Burnishability

Solderability

Experience of the dental lab

79

Type 0 Casting Alloys

very low stress-bearing restorations (small veneered one-surface inlays, veneered crowns (also metallic materials for metal-ceramic crowns produced by electroforming or sintering)

80

Type 1 Casting Alloys

low stress-bearing single-tooth restorations, e.g., veneered or unveneered one-surface inlays, veneered crowns

81

Type 2 Casting Alloys

single-tooth fixed restorations, e.g., crowns or inlays without restriction on number of surfaces

82

Type 3 Casting Alloys

multiple-unit fixed restorations, e.g., bridges

83

Type 4 Casting Alloys

thin sections subjected to very high forces (RPDs, clasps, thin veneered crowns, bridges with wide spans or small cross-sections, attachments, implant-retained superstructures)

84

Type 5 Casting Alloys

appliances requiring combination of high stiffness and strength, e.g., thin RPDs, parts with thin cross-sections, clasps

85

Gold provides

Provides ductility, tarnish and corrosion resistance

86

Copper is the principal element for

Hardening and strenghting

Reduced tarnish and corrosion resistance

87

Silver counteracts

Effect of copper n color and substitutes economically for gold without degrading mechanical properties

88

Platinum and Palladium provide

Tarnish and corrosion resistance as well as strenghting

Limited amounts small amount raises alloy melting temperatures

89

Zinc

Oxygen scavenger during melting to minimize oxidation of other elements and considered to improve castability of fluidity fo molten alloy

90

Small amounts of ___ and ____ may be present yo provide hardening and strengthening to gold alloy

Indium

Gallium

91

Very small amounts of iridium are generally incorporated to provide

Small grain size or grain refinement(improves mechanical properties, compositional uniformity in microstructure and corrosion resistance )

92

Increase in yield strength and hardness

Decrease in ductility

93

For gold Alloys, increase in total amount of elements other than gold

Gold content decreases

Decreased
Burnishability
Adjustment
Melting temperature

94

Solid solution hardening

Provided by copper platinum palladium silver and zinc

95

Grain size refinement

Iridium

96

Other hardening

Copper

97

Quenching of casting

Gives softened condition-cooling rate is too rapid for ordering transformation

98

Bench cool or furnace heat-treat

Casting (heat to 450 and cool to 250 over a 30 minute period) for hardened condition as result of ordering transformation

99

Trim vacuum formed matrix ____ from gingival margina

4-5mm

100

Zirconia is

A white powdered metal used to create dental frameworks for crowns bridges and other dental substructure

101

Zirconia indications

Anterior and posterior crowns and bridges
Post and core
Implants abutments
Orthobrackets

102

Contraindications for zirconia

Reduced inter occlusal space
Deep vertical overlap
Opposing Supra erupted tooth
Very short clinical crown

103

Advantages of zirconia

Superior esthetics

Easy preparation and cementaton

Optimal fit

High Strenght

Excellent insulating behavior

Biocompatible -no allergic response

104

Zirconia disadvantages

Expensive

Difficult to reinterivne (posts for endo)

Bond between veneer ceramic and zirconia framework is the weakest component in the layered structure

Non available longitduial study

105

_____ are known to be the longest lasting crown restorations

Gold

106

_____ restorations are among the most esthetic restorations in dentistry today and many laboratories are providing them at reasonable price

Lithium disilicate

107

______ is well proven and has had over 50 years of successful use

Porcelain fused to metal

108

Porcealain fused to metal =

PFM=MCC

109

PFM

Increased opacity
Porcelain chip off
Marginal discoloration

110

Zirconia recommend for

Molars premolars and short span posterior bridges

111

Zirconia reductions

1.5-2
1.2
1

112

Interim Restorations requirements : biologic

Protect pulp

Maintain periodontal health

Occlusal comparability

Maintain tooth position

Protect against fracture

113

Interim Restorations requirements : Mechanical

Resists functional loads

Resist removal forces

Maintain interabutment alignments

114

Interim Restorations requirements : esthetic

Easy to control

Color compatibility

Color stability

Translucency

115

Tissue surface form

Prep tooth

116

External surface form

Mold

117

External surface form material

Polypropylene shell

118

Direct procedure advantages

The patients prepared teeth and gingival tissues directly provide the TSF intermediate steps of the indirect technique are elimante

This is convienent when offic lab facilities are inadequate for efficiently producing and indirect restoration

119

Disadvantages direct procedure

Potential tissue trauma from polymerizing resin and inherently poorer marginal fit

120

Interim fixed Restoration ideal Properites

• Convenient handling: adequate working time, easy
molding, rapid setting time
• Biocompatibility (non toxic, non allergenic) • Dimensional stability during solidification
• Ease of contouring and polishing
• Adequate strength and abrasion resistance • Good appearance
• Good acceptability to patient: nonirritating,
odorless
• Ease of adding to or repairing
• Chemical compatibility with interim luting agents

121

Direct method steps

Steps
• ESF: vacuum form matrix
• TSF: prepared typodont tooth
• Lubricant: Vaseline (Brush)
• Acrylic: Trim powder and monomer (cups/dappen dishes, spatula, brush)
Slow speed handpiece, Acrylic burs, Finishing discs and Burlow wheels
• Shimstock, Accufilm,
• Patience

122

After rubbery stage is achieved why pump ESF

Prevent locking in and overheating the teeth

123

Finishing steps

Sequence?
• Acrylic bur
• Moore disks
• Burlow wheels (Margins and axial) • Diamond (Occlusal)
• Rubber points(Occlusal if needed)