Lesson 8 & 9 Flashcards by Love Dog | Brainscape

Q

metal-ceramic restoration, otherwise known as _____

A

PFM restoration (porcelain fused to metal)

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Q

one of the least conservative of tooth structures:

______ because incisal and occlusal surfaces are
always subjected to forces

A

thicker metal

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Q

one of the least conservative of tooth structures:

_______ maximum for incisal and _____ for molars

A

2 mm, 1.5 mm

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Q

porcelain fuse at temperatures of ____ and gold alloys melt
at this temperature

A

960 C

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Q

gold alloys melt
at this temperature

A

960 C

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Q

is a major consideration in the
fabrication of metal ceramic restoration

A

special alloy

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Q

FACTORS IN TOOTH PREPARATION

A

Biologic
Mechanical
Esthetic

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Q

Conservation of tooth structure

A. Biologic
B. Mechanical
C. Esthetic

A

A

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Q

Avoidance of overcontouring

A. Biologic
B. Mechanical
C. Esthetic

A

A

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Q

Supragingival margins

A. Biologic
B. Mechanical
C. Esthetic

A

A

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Q

Harmonious occlusion

A. Biologic
B. Mechanical
C. Esthetic

A

A

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Q

Protection againts tooth fracture

A. Biologic
B. Mechanical
C. Esthetic

A

A

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Q

Retention form, resistance form, deformation

A. Biologic
B. Mechanical
C. Esthetic

A

B

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Q

Minimum display of metal

A. Biologic
B. Mechanical
C. Esthetic

A

C

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Q

Maximum thickness of porcelain

A. Biologic
B. Mechanical
C. Esthetic

A

C

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Q

Porcelain occlusal surfaces, subgingival margins

A. Biologic
B. Mechanical
C. Esthetic

A

C

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Q

→ teeth that require complete coverage

→ gingival involvement
→ in conjunction with post & crown

A

METAL-CERAMIC CROWN PREPARATION

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Q

can be modified for cingulum & occlusal restorations

A

METAL-CERAMIC CROWN PREPARATION

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Q

→ if all-ceramic crown is contraindicated

o not efficacious for long spans

A

METAL-CERAMIC CROWN PREPARATION

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Q

CONTRAINDICATIONS

large pulp chamber

intact buccal wall

presence of active caries

→ untreated periodontal disease
→ when more conservative retainer is technically feasible

A

METAL-CERAMIC CROWN PREPARATION

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Q

ADVANTAGES

→ strength of cast metal with the esthetics of ceramics
→ retentive qualities are excellent
→ easy correction of axial form
→ preparation is much less demanding than for partial-coverage
retainers

A

METAL-CERAMIC CROWN PREPARATION

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Q

DISADVANTAGES
→ requires significant tooth reduction
→ difficulty obtaining accurate occlusion in glazed porcelain → shade selection can be difficult
→ inferior esthetics in comparison with all-ceramic crown
→ subject to brittle fracture
→ increases potential for periodontal disease
→ many procedural steps are required

A

METAL-CERAMIC CROWN PREPARATION

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Q

RECOMMENDED PREPARATION for
ANTERIOR:

Labially

A

1.5 mm

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Q

RECOMMENDED PREPARATION for
ANTERIOR:

Incisally

A

2 mm

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Q

STEP-BY-STEP PROCEDURE FOR METAL-CERAMIC TOOTH PREPARATION

A

(1) Depth Grooves
(2) Incisal (Occlusal) Reduction
(3) Labial (Buccal) Reduction
(4) Proximal Cut
(5) Lingual Reduction
(6) Finishing
(7) Smoothing and Finishing

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Q

DEPTH GROOVES
place (3) depth grooves:

A

o center of facial surface
o one each in mesiofacial and distofacial line angles

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Q

DEPTH GROOVES

placed in (2) planes:

A

Cervical Portion

Incisal (Occlusal) Portion

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Q

parallels the long axis of the tooth

A

Cervical Portion
(DEPTH GROOVES)

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Q

follows the normal facial contour (1.8 mm)

A

Incisal (Occlusal) Portion

(DEPTH GROOVES)

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Q

FACIAL REDUCTION

facial reduction in the _____ & ____

A

cervical and incisal planes

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Q

determines the path of placement of the completed restoration

A

Cervical Plane

(FACIAL REDUCTION)

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Q

provides the space needed for the porcelain veneer

A

Incisal (Occlusal) Plane

FACIAL REDUCTION

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Q

achieve the necessary. ____ mm clearance on the incisal depth grooves

A

2 mm

Q

place three depth grooves (1.8 mm deep) in the incisal edge of an anterior tooth

A. Anterior Tooth
B. Posterior Tooth

A

A

Q

clearance must be a minimum of 2 mm; cusp inclines 1.5 to 2 mm of clearance in intercuspal tapered

A. Anterior Tooth
B. Posterior Tooth

A

B

Q

allow 2 mm of clearance for adequate material thickness to allow translucency in the completed restoration

A

INCISAL (OCCLUSAL) REDUCTION

Q

in posterior teeth:

o may still be restorable with less reduction because esthetics
is not as critical

A

INCISAL (OCCLUSAL) REDUCTION

Q

caution:
o excessive occlusal reduction will shorten the axial preparation walls and thus is a common cause of inadequacies in retention and resistance form in the completed preparation

o loss of retention form can be especially problematic on anterior teeth (on which, because of tooth form, most of the retention is derived from the proximal walls)

A

INCISAL (OCCLUSAL) REDUCTION

Q

→ use a tapered, round-ended diamond bur
→ 1.2 - 1.5 mm of reduction for translucency in the restoration
→ greater thickness of alloy at incisal area than any other tooth
surface
→ bur position at 45 degrees linguo-incisally
→ reduce half of the incisla area at a time
→ reduce one cusp at a time

A

INCISAL (OCCLUSAL) REDUCTION

Q

FACIAL REDUCTION

two plane reduction:

Cervical Plane-

Incisal Plane -

A

1.0 mm; 1⁄3, 1.3 mm; 2⁄3

Q

→ 0.5 mm apical to crest of free gingiva
→ reduce with the bur in oblique position
→ tenon system

A

FACIAL REDUCTION

Q

→ recommended:
o 6 degree taper between opposing axial walls
→ shoulder margin at 1 mm thick
→ parallel walls with another abutment
→ avoid hitting adjacent tooth
→ shoulder margin below the contact point
→ use flat-end diamond bur

A

PROXIMAL CUT OR REDUCTION

Q

Size of Linguofacial Wall Reduction:

Chamfer Margin

Supragingival

A

0.5 mm

Q

Size of Linguofacial Wall Reduction:

Axial Wall Height

A

1.5 mm

Q

Size of Lingual Fossa Reduction:

Centric Contacts on Metal

A

1 mm thickness

Q

Size of Linguo-axial Wall:

Height for path of placement and anti-rotation

A

1.5 mm

Q

Size of Linguo-axial Wall:

Use round-ended tapered diamond bur and submerge halfway into the tooth structure to create chamfer margin

Size of the width?

A

0.5 - 0.6 mm width

Q

Size of Linguo-axial Wall:

Use flame-shaped or football shaped diamond bur in preparing the lingual surface of anterior teeth

A

1 mm thickness

Q

The margin must provide distinct resistance to vertical displacement of the tip of a periodontal probe or an explorer and it must be smooth and continuous circumferentially.

A

FINISHING LINE

Q

FINISHING LINE

shoulder finish line should be_______ degrees

A

90-120

Q

FINISHING LINE

use ___ in remaining unsupported enamel

A

chisel

Q

FINISHING LINE

_____ finish line in lingual

A

chamfer

Q

FINISHING LINE

avoid “ ____” of the chamfer margin

A

lipping

Q

FINISHING LINE

→ controlled tissue displacement can be helpful when the margin is finished with a _____ or another rotary instrument
→ avoid undercuts
→ round-off internal line angles, incisal and occlusal margins
→ taper and parallelism

A

fine-grit diamond

Q

(1) Platinum foil matrix adapted to a die
(2) Hot pressing/heat-pressed
(3) Sip-casting
(4) Milling

A

TECHNIQUES IN FABRICATION FOR ALL-CERAMIC RESTORATIONS

Q

ZIRCONIA another name

A

SINTERING-MILLING

Q

E-MAX another name

A

HEAT-PRESSED

Q

→ three times stronger than porcelain

A

ZIRCONIA
(SINTERING-MILLING)

Q

→ can withstand wear and tear without chipping

→ tolerate forces of mastication and bruxism

→ less stress and damage on opposing pieces

A

ZIRCONIA
(SINTERING-MILLING)

Q

made from lithium disilicate ceramic

A

E-MAX

Q

ideal for crowns

A

E-MAX (HEAT-PRESSED)

Q

→ more translucent compared to zirconia
→ 10-15 years (fracture)

A

E-MAX (HEAT-PRESSED)

Q

→ high esthetic requirement
→ considerable proximal or facial caries
→ incisal edge reasonably intact
o to support the restoration, particularly in the incisal area, where porcelain thickness must not exceed 2 mm
o otherwise, the brittle material will fail
→ endodontically treated teeth with posts and cores
→ favorable distribution of occlusal load because of the relative
weakness of the restoration

A

INDICATIONS for ALL-CERAMIC CROWN PREPARATION

Q

→ when a more conservative restoration can be used
→ when superior strength is warranted and metal-ceramic crown is
more appropriate
→ extensive caries
→ insufficient coronal tooth structure for support
→ thin teeth facio-lingually
→ unfavorable distribution of occlusal load
→ bruxism
→ teeth with short clinical crowns
o they do not offer adequate support for all-ceramic crowns

A

CONTRAINDICATIONS for ALL-CERAMIC CROWN PREPARATION

Q

→ esthetically unsurpassed; excellent translucency
→ good tissue response even for subgingival margins
→ slightly more conservative of facial wall than metal-ceramic
restorations

A

ADVANTAGES in ALL-CERAMIC CROWN PREPARATION

Q

→ reduced strength in comparison with metal-ceramic crown

proper preparation extremely crucial
→ among least conservative preparations
→ brittle nature of material
→ can be used only as single restoration

A

DISADVANTAGES in ALL-CERAMIC CROWN PREPARATION

Q

centric contacts are best confined to the middle third of the lingual surface

A

ALL-CERAMIC CROWN OCCLUSION

Q

achieved by restricting the taper of proximal walls

A

Retention Form

Q

wing-type preparation offers more resistance than wingless counterpart (crown length)

A

Resistance Form

Q

should exhibit two plane reduction

A

Esthetic Zone

Q

cervical plane is 1⁄3 of preparation height

A

Anteriors

Q

Shoulder margin degree?

A

90-120 degree (hatchet/chisel)

Q

Premolars and Molars

cervical and occlusal plane often ______ each other in height

A

approximate

Q

____ should be avoided as it often leads to overreduction

A

Undercut

Q

should be avoided because this may lead to pulpal exposure

A

Excessive Convergence

Q

0.5 mm; should be smooth and continuous and provide distinct resistance to vertical displacement

A

Chamfer Margin

Q

must be smooth and continuous circumferentially

A

Finishing Margin

Q

Line Angles and Internal Line Angles should be _____

A

rounded

Q

True or false

all-ceramic restoration are most esthetically pleasing because of the absence of underlying metals to block light transmission and it resembles natural tooth better in terms of color and
translucency

A

True

Q

chief disadvantage is fracture susceptibility but lessened by use
of resin-bonded technique and higher strength ceramics

A

ALL-CERAMIC RESTORATIONS

Q

one of the least conservative of tooth structures:

____ mm maximum for incisal and _____ mm for molars

A

2 mm, 1.5 mm