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Fixed Pros II > Week 5- Pontics > Flashcards

Week 5- Pontics Flashcards

1
Q

what dimension does bone loss of the alveolar ridge occur in after extraction

A

horizontal dimension and buccally

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2
Q

what percentage of alveolar bone dimension can be lost after tooth extraction

A

50%

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3
Q

alveolar bone loss has been reported to be up to _____

A

6-7mm

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4
Q

two thirds of loss of bone volume can occur within the ______ of tooth extraction

A

first three months

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5
Q

reductions of _____ in vertical ridge height have been noted

A

2-4mm

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6
Q

what is the pattern of vertical bone resorption often accompanied by

A

a ridge that has moved in a palatal/lingual direction and has atrophied vertically

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7
Q

sockets that were preserved with bone grafting and/or membrane on average lost _____ less of ridge with and _____ less of ridge height

A

2mm; 1mm

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8
Q

sockets that were grafted had _____ more bone volume when compared to sockets that were not grafted

A

20%

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9
Q

maxillary sites lost ____ bone than mandibular sites

A

less

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10
Q

what percentage of patients have a normal ridge after extraction

A

8%

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11
Q

what percentage of patients have a class III ridge after extraction and what is a class III ridge

A
  • 56%
  • F-L and OG height affected
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12
Q

what percentage of patients have a class II ridge after extraction and describe a class II ridge

A
  • 3%
  • O-G height is affected
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13
Q

what percentage of patients have a class I ridge after extraction and describe a class I ridge

A

-32%
- FL width is affected

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14
Q

what is the most common class of alveolar ridge deformity after extraction

A

class III

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15
Q

what does the pre-treatment assessment include

A
  • evaluate the dimensions of the edentulous space
  • evaluate the positions of the abutment teeth to assess the favorability for a bridge
  • evaluate the possible occlusal outcomes
  • is there a need to reposition the teeth orthodontically prior to fixed work
  • wax up!!
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16
Q

what materials are used for pontics

A
  • cast metal
  • metal-ceramic
  • zirconia or all ceramic
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17
Q

when two materials are used, the finish line for their joining should not be on the:

A

edentulous ridge

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18
Q

what are the ideal characteristics we look for in a pontic design

A
  • esthetic
  • biologic
  • mechanical
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19
Q

what are the esthetic characteristics we look for in pontic design

A
  • apperance of replacement
  • replication of emergence from ridge
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20
Q

what are the biologic characteristics we look for in pontic design

A
  • ability for the patient to clean well around the bridge/pontic area
  • allows for healthy tissue
  • patient comfort of the bridge
  • harmonious occlusion
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21
Q

what are the mechanical characteristics we look for in pontic design

A

rigid framework to resist deformation or fracture

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22
Q

ideally, a pontic should have the same _____ height as the original or neighboring teeth

A

inciso- gingival

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23
Q

when resorption of bone has taken place, the pontic does what

A

changes shape in order to keep in contact with the ridge concavity

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24
Q

contour of the pontic needs to be blended smoothly to avoid:

A

a ledge at the cervical

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25
Q

contour in apical half should approximate:

A

the length of the adjacent teeth

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26
Q

the facial surface is altered to curve:

A

from the gingival-facial to the middle of the facial surface

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27
Q

what happens when the pontic doesnt adapt to the ridge well

A

esthetics, speaking and food impaction can become troublesome

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28
Q

pontic ridge contact should ideally be on what kind of tissue

A

keratinized

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29
Q

when pontic contact is on non-keratinized tissue:

A

ulceration and constant irritation can occur

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30
Q

pontic contact with ridge should not:

A

inflict pressure on the tissue

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31
Q

pontic shape in contact with tissue should also be:

A

convex

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32
Q

what happens when the pontic contact is too heavy

A

tissue/bone resorption

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33
Q

what happens when the pontic contact is too light

A

food impaction, esthetics compromised

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34
Q

convex shape of the gingival aspect of pontic allows for:

A

easier cleaning for patient

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35
Q

what keeps out food and debris from being trapped under the pontic

A

fullness of pontic shape and proper gingival embrasures

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36
Q

what tools can be used to keep up oral hygiene under pontics

A
  • floss threader
  • super floss
  • proxabrush
  • rubber tip
  • water pik
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37
Q

what size of pontic connectors are necessary for strength

A

-4mm OG
- 3-4mm FL

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38
Q

what is the order of material strength from greatest to least

A

metal > zirconia > porcelain > acrylic

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39
Q

pontic connectors should not impinge on:

A

embrasures

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40
Q

do you want occlusion on pontics

A

yes just should be equal to or lighter than adjacent teeth

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41
Q

what pontic position creates torque on connectors and abutments leading to failure

A

pontics placed outside of the inter-abutment axis

42
Q

what is the number 1 reason for bridge failure

A

occlusion

43
Q

occlusion development with a bridge should replace ideal occlusion:

A

MI contacts, working and non-working contacts in lateral excursions, protrusive contacts and canine guidance

44
Q

what are the types of pontic design

A
  • ridge lap (saddle)
  • modified ridge lap
  • hygenic-perel modification
  • conical
  • ovate
45
Q

describe a ridge lap pontic and what is is also known as

A
  • AKA saddle pontic
  • not used any longer
  • forms a large concave contact area with ridge
  • patient not able to clean
  • creates tissue inflammation leading to tissue ischemia and necrosis
46
Q

describe the hygenic pontic and what is it also known as

A
  • AKA sanitary pontic
  • no contact with ridge
  • at least 2-3mm of space between the ridge and pontic
  • patient can easily clean without the pontic being a food trap
  • only for use in non-esthetic areas
  • design and shape is convex in all directions
47
Q

what is the modified hygenic pontic used for

A
  • to increase strength of bridge in connectors with hygienic pontic
48
Q

what is the issue that is created with modified hygienic pontics and what can be done to overcome that

A
  • deflection is increased with less occlusal gingival height
  • make connectors larger
49
Q

describe conical pontics

A
  • passive contact with ridge crest
  • rounded and cleansable
  • triangular embrasure space can trap food
  • best suited for thin mandibular ridges
  • also not best for esthetic areas
50
Q

describe the modified ridge lap pontic

A
  • passive contact facial side of ridge crest
  • can appear very esthetic
  • convex tissue surface contact
  • used frequently in the esthetic areas
  • shape can help keep food from trapping
  • cleansability much easier for patients
51
Q

what is the most common pontic design

A

modified ridge laps

52
Q

describe the shape of modified ridge lap pontics

A
  • convex in all directions except for a small concavity on the lingual side of the F-G aspect of the pontic
  • contact area is meant to be minimal
  • lingual side needs to be smooth and highly polished
  • tissue contact okay but should not put pressure on the tissue
  • keep tissue contact on keratinized tissue
  • tissue contact shaped like a T
53
Q

what is the one part of the modified ridge lap pontic that is concave

A

the area of contact

54
Q

describe the ovate pontic

A
  • blunt rounded pontic shape that is set into a concavity in the tissue of the edentulous ridge
  • generally requires planning
  • cleansable by well educated and motivated patients
  • highly esthetic
55
Q

what type of planning do ovate pontics require

A
  • pre-prosthetic surgery via immediate provisionalization after extraction
  • surgery/modification with provisional to develop tissue shape and contour
  • ovate pontics keep a slight pressure on the tissue to maintain the effect of emerging from the ridge
56
Q

which are the esthetic pontic designs

A
  • modified ridge lap
  • ovate
57
Q

what is the most common pontic and why

A

modified ridge lap because it is esthetic but requires less effort for the patient and doctor

58
Q

is sx required with modified ridge lap

A

no

59
Q

what are the typical connector dimensions

A
  • height: 3-4mm
  • width: 3-4mm
60
Q

what shape is better for gingival embrasures: U shape or Vs haped

A

U shaped

61
Q

connectors are shaped to be concave in the:

A
  • buccal lingual and the mesial distal toward the ridge
62
Q

connector U shape from:

A

occlusal to gingival

63
Q

why is the U shape connector preferred over the V shape

A
  • U shape is stronger
  • U shape less likely to fracture
64
Q

if you increase the height by 2x you increase the strength by:

A

a cube

65
Q

what shape are anterior connectors

A

tear drop

66
Q

anterior connectors are placed more ______ for esthetics

A

lingually

67
Q

anterior connectors are longer _____ for strength

A

inciso-gingivally

68
Q

metal connectors can be ____ in height

A

3mm

69
Q

in posterior connectors occluso-gingival height is more important than _____ for strength

A

buccal lingual width

70
Q

posterior connector is what shape

A

heart shaped

71
Q

in all ceramic bridges the connector size is at least _____

A

4mm and possibly needs to be larger

72
Q

in all ceramic bridges, U shaped connectors need a ________ at the gingival embrasure

A

large radius

73
Q

full strength zirconia shows ____ fracture resistance compared to all ceramic

A

increased

74
Q

what is the difference in connector size between all ceramic and full strength zirconia

A

none they need to be the same size

75
Q

metal frameworks are assembled in two ways:

A
  • cast/milled as one piece
  • two or more pieces are soldered together
76
Q

when can laser welding be used

A

in titanium alloy situations

77
Q

when can CAD/CAM be used

A

to make a one piece bridge framework with ceramics/zirconia

78
Q

what is the issue with single piece casting

A

distortion- greater the length, the increased distortion

79
Q

longer span bridges are often:

A

cast in multiple pieces and soldered together

80
Q

what can you do if a FPD metal framework does not fit due to distortion

A

you can cut between a pontic and retainer, re-seat each smaller piece to verify the individual fit and capture the new seating with acrylic. this is then sent to the lab to solder the new pieces together

81
Q

what is soldering and explain the process

A

joining of metals by fusion of filler metal bonding to each of the parts being joined
- the bond is created by wetting the surface of parent metals with liquefied solder
- the metal framework does not melt during this

82
Q

what is brazing

A

a specific form of soldering when the filler material has a melting temperature above 450 degrees celsius

83
Q

what do we want solder to do for us

A
  • resists tarnish and corrosion
  • the fusion temperature 100-150 degrees farenheit below that of the substrate metal
  • free flow when melted
  • resists pitting
  • is strong
  • matches color of the two parts being joined
84
Q

solder is classified by:

A

fineness

85
Q

describe fineness

A
  • fineness is the parts per thousand of gold in a solder
  • 560 fine = 650 parts gold per thousand parts
86
Q

higher fineness ____ the melting range

A

increases

87
Q

higher fineness ____ resistance to tarnish or corrosion

A

increases

88
Q

higher fineness results in____ hardness

A

decreased

89
Q

what does more gold do to fineness

A

lower it will melt and more flexibility, less hardness

90
Q

what factors affect the accuracy and prognosis of soldered connectors

A
  • connector space
  • metal surface preparation
  • indexing technique for investment
91
Q

what does a proper connector space allow for in solder accuracy

A
  • allows the solder to flow in between
  • allows for thermal expansion and shrinkage of the solder
  • small enough to minimize distortion from the solder shrinkage as it cools
  • large enough to allow for a strong connector
  • parallel and flat with a space for thickness the size of a business card- 0.2mm
92
Q

how should the metal surface be prepared for soldering

A
  • needs to be clean and uncontaminated
  • needs to have a satin finish instead of highly polished
93
Q

describe the indexing technique for investment

A
  • flow auto-polymerizing acrylic resin into space to hold two pieces together. each side should be fully seated with margin integrity checked and verified
  • make an occlusal plaster index to send to the lab for soldering. framework should be solidly planted in plaster index so that enough of the coronal portion is covered so framework can be held in place
94
Q

what is flux and what does it contain

A
  • enables solder to wet and spread over clean metal surfaces
  • removes oxides and prevents further oxide formation
  • contains borate
95
Q

what does anti-flux do and what does it contain

A
  • limits the spread of the solder
  • contains graphite or rouge
96
Q

what are the two types of soldering

A
  • pre-ceramic veneer soldering
  • post- ceramic veneer soldering
97
Q

describe pre-ceramic veneer soldering

A
  • uniting components of the same alloy before porcelain is fired
  • uses high fusing solder and is stronger
  • melt solder with a torch
  • solder has lower melting temp than alloy, but higher melting temp that porcelain firing temperature
  • less technique sensitive
98
Q

describe post ceramic veneer soldering

A
  • uniting components of the same allow AFTER porcelain is fired
  • uses low- fusing solder and is not as strong
  • melt solder in oven
  • solder has lower melting temp than alloy and porcelain
  • more technique sensitive
  • can compensate for slight discrepancies or distortions that occur after the porcelain is fired
  • porcelain can crack in area of solder joint during solder process
99
Q

why cant you add porcelain after post- ceramic veneer soldering

A

temperature of porcelain firing is too high and you’d melt the low fusing solder

100
Q

when would you use the post ceramic veneer soldering

A

ideally you dont want to unless you absolutely have to

101
Q

what do you do if you have open contact with an all metal or PFM crown

A
  • addition soldering
  • add metal to contact area
  • smooth and shape contact area
102
Q
A

Fixed Pros II (13 decks)

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