9. Fixed dental bridges Flashcards
1
Q
What is a pontic?
A
A missing tooth restored by a structure
2
Q
What is a bridge?
A
FPD that replaces missing teeth
3
Q
Advantages of bridges? (5)
A
- Firm Attach.
- Esthetics.
- Comfort for the patient.
4
Q
Why is a bridge better than an RPD?
A
- hygiene
- better load transfer to abutment teeth
5
Q
What are the different types of bridges? (6)
A
- Fixed
- Cantilever
- maryland
- with interlocks
- removeable
- with hygienic pontics
6
Q
Fixed bridge characteristics? (3)
A
- Most common type of bridge.
- Retainers are cemented onto the abutment teeth.
- Rigid connectors
7
Q
Cantilever bridge characteristics? (5)
A
- The pontic has a connector and a retainer only on one side.
- Less use due to the implants rehabilitation.
- Occlusal overload of the abutment teeth.
8
Q
Cantilever bridges need to be careful with… (2)
A
- Occlusion
- periodontal attachment
9
Q
What law is important to think about for cantilever bridges?
A
Ante’s
10
Q
What is ante’s law for bridges?
A
The total root surface/periodontal membrane area of abutment teeth must be equal to or exceed the total root surface area of the teeth being replaced
11
Q
What missing teeth can we use cantilever bridges for? (3)
A
- upper lateral incisors
- First premolars
- First molars
12
Q
How do we use a cantilever bridge for upper lateral incisors? (2)
A
- abutment: canine and first premolar
* watch for crown-to-root ratio and eccentric movements
13
Q
How do we use a cantilever bridge for first premolars?
A
Abutment: 2nd premolar and 1st molar
14
Q
How do we use a cantilever bridge for first molars?
A
- Abutment: 1st and 2nd premolar
- short pontic: 1/2 MD distance from 1st to 2nd premolar
15
Q
Characterisitcs of maryland bridges? (4)
A
• Metal or ceramic “wings” over abutment teeth.
• Cemented with resin cements.
• Rely on adhesion to stay in place.
• Very small preparation on the lingual surface of abutment teeth
(over enamel).
16
Q
Indications for maryland bridges? (3)
A
Provisional restorations
- during implant healing
- young patients
17
Q
Bridges with interlocks characteristics? (5)
A
- Cannot be removed. It is fixed.
- Non-rigid connector
- Used as broken-stress mechanical union
- Two parts joined by an attachment (interlock)
18
Q
Indications of bridges with interlocks?
A
Situations of long bridges or edentulous pieces
on both sides of a tooth
19
Q
What are the parts of a bridge with interlocks? (3)
A
- Patrix and matrix joined by an attachment (interlock)
- Patrix should be at the mesial surface of the pontic.
- Matrix should be at the distal surface of the retainer.
20
Q
What is a frequent complication of bridges with interlocks ?
A
- intrusion of one of the parts,
- usually the matrix
21
Q
Where are bridges with interlocks placed? (2)
A
- Placed in the middle abutment.
* If placed in the terminal ones—pontic acts as lever arm
22
Q
Where does the female go in a bridge with interlocks?
A
On the distal surface of the retainer cemented to the abutment
23
Q
Where does the male go in a bridge with interlocks?
A
Mesial surface fo the pontic
24
Q
Bridges with interlocks: movement? (3)
A
- Movement will seat the key into the keyway
- vertical forces = mesial movements
- placed mesially, the movement can unseat the key
25
Vertical forces and bridges with interlocks?
Mesial direction of movements
26
Indication of bridges with interlocks?
Unparalleled abutment teeth
27
Bridges with interlocks are rarely used because..
of the intrusion produced
28
How do you combat the intrusion produced with bridges with interlocks?
non-rigid connector is placed over the pm to not
| increase the tilting of the molar
29
Removable bridge characteristics? (2)
* Large ridge defects
| * Friction retention.
30
Retentive devices for removable bridges?
- bar
| - telescopic crowns
31
When do we use telescopic crowns?
- removable bridges
| - for badly aligned abutment teeth
32
What are the parts of a telescopic crowns of removable bridges?
- primary coping
| - secondary coping
33
Characteristics of telescopic crowns primary copings for removable bridges? (3)
◦ Cemented to the abutment teeth.
◦ 3-6º taper.
◦ Adequate height.
34
Characteristics of telescopic crowns secondary copings for removable bridges? (2)
◦ Are joined to the removable part.
| ◦ Not cemented to the primary copings.
35
Characteristics of low resistance all-ceramic bridges? (4)
```
• Feldspathic
• Aesthetics
• Veneering
layers
• 70-90Mpa
```
36
Characteristics of moderate resistance all-ceramic bridges? (3)
• Lithium Disilicate
• Monolithic or with veneered
layers over core
• 360-400Mpa
37
Characteristics of moderate resistance all-ceramic bridges? (3)
• Zirconia
• Monolithic or with veneered
layers over core
• 900Mpa
38
The higher the resistance of all ceramic bridges, the...
less translucency
39
LDS bridges can only be used.. (3)
- for anterior bridges
- max 3 pieces
- last abutment = 2nd premolar
40
LDS aesthetic vs resistance?
Higher esthetics than resistance
41
Which LDS should we use for bridges? (2)
- monolithic (higher survival rate)
| - better is pressed
42
do LDS bridges need connectors?
Thick connectors : 16mm2 (4x4)
43
Zirconia bridges characteristics? (2)
- high resistance
| - less aesthetic
44
Zirconia new options for bridges?
- against chipping
| - with high aesthetic
45
Zirconia bridges connector?
Thicker than metal
46
What was the old zirconia bridge option?
- Zirconia core + aesthetic veneer
| - high risk of chipping (main failure reason)
47
What was the new zirconia bridge option? (5)
- Monolithic
- No chipping
- solidity
- strength
- suited for bruxists
48
What are the masticatory forces a material must support without fracturing over molars?
300-800N
49
What are the masticatory forces a material must support without fracturing over anterior sectors?
60-200N
50
What are the masticatory forces a material must support without fracturing for parafunction?
1000N
51
What are the masticatory forces zirconia supports?
900-1200N
52
What are the masticatory forces pressed LDS supports?
400N
53
What are the masticatory forces milled LDS supports?
360N
54
Indications for zirconia bridges?
- teeth and implants
- posterior (better when monolithic)
- unitary crowns
- bruxists (monolithic)
- discolored or ETT
55
Where should zirconia bridges not be used? (2)
- Anteriorly
| - b/c High opacity
56
What different zirconia's can be used in a bridge? (3)
- Monolithic
- HT Zr
- Layered Zr core
57
Why do we use monolithic zirconia in bridges? (3)
- strong and resistant
- full contour crowns
- FC bridges
58
Why do we use HT zirconia in bridges? (2)
- high translucent
| - good aesthetics for anterior sector
59
Characteristics of layered zirconia in bridges? (2)
- with feldspathic veneer
| - Not ideal for posterior sector
60
Strength of monolithic zirconia bridges?
High
61
monolithic zirconia bridges biocompatibility?
Less risk of allergies (Ni, Pd)
62
monolithic zirconia bridges marginal fit?
Good and accurate
63
monolithic zirconia bridges hypersensitivity? (2)
- Reduces hypersenstivity
| - resistant to temperature changes
64
Monolithic zirconia bridges X-rays?
Radiopacity
65
Monolithic zirconia bridges corrosion?
No corrosion
66
Monolithic zirconia bridges clinical longevity?
Good
67
Monolithic zirconia bridges preparation?
Less tooth prep is required
68
Monolithic zirconia bridges aesthetics compared to PFM?
Mono Zr better aesthetics
69
Monolithic zirconia bridges vs LDS?
LDS better aesthetics
70
Monolithic zirconia bridges and dark substrate colors?
Can mask them
71
Monolithic zirconia bridges prothetic space?
Less prosthetic space needed
72
Monolithic zirconia bridges abrasiveness?
Not very abrasive when polished correctly
73
Monolithic zirconia bridges working time?
Reduction of working time
74
Zirconia bridge connectors? (3)
- require a min volume as they fracture often
- Dimensions are directly related to flexural resistance and resistance to fracture
- require more volume than PFM bridges
75
Zirconia bridge connector dimensions? (3)
Abutment- Pontic:
- 7mm2 for anterior bridges
- 9mm2 for posterior bridges
Bridges with more than 1 pontic: 12mm2
76
Zirconia bridge finish line? (3)
- Finish line: rounded shoulder or chamfer
- Finish Line of 0,8 to 1,2 mm
- Monolithic FL: 0,5mm
77
Zirconia bridge occlusal reduction?
0.6-1.5mm
78
Posterior bridge connectors for zirconia?
9mm2
79
Anterior bridge connectors for zirconia?
7mm2
80
Size of bridge connectors for zirconia between pontics?
12mm2
| - subject to higher loads and stress
81
Ridge lap pontic characteristics? (4)
- Concave shape, surround the ridge buccally and
lingually/palatal
- Intimate adaptation to the gingiva
- Produces inflammation and possible bone resorption
- Not recommended
82
Ridgelap pontic aesthetics and hygiene? (2)
- Difficult hygiene
| - Very aesthetic
83
Conical pontic aesthetics and hygiene? (2)
- very hygienic
| - poor asethtic
84
Conical pontic characterisitcs?
- One contact point with gingiva
| - convex shape MD and BL
85
Conical pontic cons? (2)
- Not very comfortable
| - not to be used on upper law, creates phonetic problems
86
Where are conical pontics indicated?
Posterior areas over thin ridges
87
Where does a modifed ridge lap pontic go?
- extends over buccal surface
- doesn't surpass bone ridge lingually
- contacts gingiva slightly over the ridge
88
Pro's of modified ridge lap pontic?
- Good hygiene
| - Good aesthetic (design creates illusion of real tooth)
89
Ovoid pontic bridge characteristics?
- Pontic goes into the concavity created in the gingiva
- most aesthetic
- preserve interdental papilla or creates it
- moderately easy to clean
90
Where do you use an ovoid pontic?
Only anterior sector with high esthetic needs
91
Ovoid pontic steps? (3)
- First shaped with provisional right after the extraction
1. concavity created with rounded bur
2. provisional placed so tissues heal with the shape
92
What is important for ovoid pontic success?
Provisionalization step
93
Hygienic pontic location?
- separated from the ridge
| - atleast 3mm gap, minimum 1mm from edentulous ridge
94
What volume is needed for a hygienic pontic?
3mm at least
95
Con's of the hygienic pontic?
- Zero aesthetic
- not comfortable
- rigid alloy
96
Indications of the hygienic pontic? (3)
- Periodontitis with poor oral hygiene.
- Handicapped patients.
- Epilepsy: gingival hypertrophy.
97
Bridge connector rigidity depends on...? (3)
Adequate diameter minimums:
- Metal: 4mm2 (2x2)
- High strength ceramic: 16mm2 (4x4)
98
Bridge connector shape resistance?
- Triangular = more resistant where the vertical axis is the bigger one
99
Connector width? (2)
- 1/3 to 2/4 of the B-P diameter
| - Also depends on the length and alloy material
100
Connector height ? (2)
- Far from the papilla's to create embrasures for the hygiene
- Joins at the medium third, slightly below the fossae of the retainers
101
Depending on the connector, we can classify the bridge as...
- Fixed-fixed
| - Fixed-removeable (combined)
102
What is a fixed-fixed bridge?
- Classical: rigid connectors, cemented
- Cantilevler (in extension)
- fixed removable: cemented retainers, removable structure on top over telescopic crowns or a bar
- Adhesives (maryland)
- Hygienic
103
What are the different retainers for bridges?
- intracoronal
| - extracoronal
104
What is an intracoronal retainer for bridge?
Inlay
105
What is an extracoronal retainer for a bridge?
Full coverage crown
106
Extracoronal bridge retainer characteristics?
- Provide better protection to abutment teeth
- 3/4 crowns
- reverse 3/4 crowns
- 7/8 crown
107
What are the different steps of bridge treatment planning? (5)
1. Assessment of abutment teeth
2. Assessment of edentulous spaces
3. Biomechanical considerations
4. information to the patient
5. possible options based on what teeth are missing
108
Bridge treatment planning: what do we assess on the articulator? (4)
- Prosthetic space
- Mesialisations
- Occlusion
- Lateral guidance
109
What factors do we consider when assessing abutment teeth? (4)
- Pulp vitality
- Condition of clinical crown
- periodontal condition
- root condition
110
What is the optimal situation for an abutment tooth's pulp vitality?
Vital tooth without caries or restorations
111
Bridges: If an abutment tooth has endodontic treatment... (3)
- Can be used for FPD
- Ferrule effect is important
- bridges fail 2x more than in a vital tooth
112
Does every abutment tooth in a bridge need endo treatment?
NO
113
When is an endo treatment indicated in an abutment tooth for a bridge? (3)
- If preparations will need to go into the pulp
- accidental pulp exposure
- irreversible pulpitis symptoms after preps
114
Ideally, the condition of the clinical crown of an abutment for a bridge should ...
Have no caries, abfractions, erosions, abrasions or restorations
115
If the abutment to a bridge has a survey line under the gingiva, what should we do? (3)
- Consider crown lengthening
- bad situation
- ex. gingival hyperplasia
116
The clinical crown of an abutment for a bridge should not be...
expulsive
117
The size of clinical crown of an abutment for a bridge? (3)
- Ideally A bigger or equal to B
- Too short clinical crowns will provide very little retention.
- The bigger the crown the better the retention
118
The position of clinical crown of an abutment for a bridge? (3)
- Ideally no incline and no
rotation.
- Straight abutments = good path of insertion
- Tooth preparation can correct inclination to a certain degree.
119
Whats the relationship between the clinical and anatomical crown of an abutment for a bridge? (2)
- usually the clinical crown is shorter
| - enamel below the gingiva
120
When can a clinical crown be longer than the anatomic crown? (2)
- over erupted tooth
| - gingival recession
121
How do you prepare an abutment for a bridge if the clinical crown is longer than the anatomic crown? (3)
◦ Supragingival finish line if possible.
◦ Metal collar (when esthetics are not critical).
◦ At esthetic areas: over cementum (try to achieve maximum fit).
122
What are the periodontal conditions allowed for an abutment tooth? (5)
- No gingivitis
- no more than 3mm probing depth
- at least 2mm of attached gingiva
- no furcation defects
- no mobility
123
If periodontal treatment has to be preformed on an abutment, what are the guidlines?
Wait atleast 2 months to get stable gingival level after root scaling
124
Abutments and larger teeth?
Greater surface area = better ability to support forces
125
Ante's law for a missing first molar?
Surface of the 2nd premolar and 2nd molar is bigger => GOOD PROGNOSIS
126
Ante's law for a missing first premolar and first molar?
surface of the retainers and pontics are equal
127
Ante's law for missing premolars and first molar?
- missing teeth surpass surface of retainers
- Bad prognosis
- should not use a bridge here
128
What do we look for radiographically when assessing an abutments periodontal health? (4)
- Even periodontal ligament
- No bone resorption
- small horizontal bone loss can be acceptable
- no occlusal trauma signs
129
Radiological assessment of an abutment tooth should yield images with... (4)
- Adequate crown-to-root ratio.
- No periapical radiolucencies.
- No root resorptions.
- No cementomas or hypercementosis.
130
How do we assess the crown to root ratio of an abutment?
- radiographically
| - measure from bone crest level
131
What is the ideal crown:root for abutment teeth?
1/2
132
What is the minimum acceptable crown to root ratio for an abutment?
1/1
133
Assesment of abutment teeth: the crown to root ratio has to be considered with... (3)
- Antagonist arch (CD, FD…).
- Periodontal condition of the antagonist arch.
- Length of the edentulous space.
134
Abutments and single rooted teeth? (3)
◦ Oval section ones are better than round section roots .
◦ E.g: upper lateral incisors are not good teeth.
◦ Better if they are slightly curved.
135
Abutments and multirooted teeth? (3)
◦ Better behavior and retention
◦ Divergent roots are better than fused ones
◦ Better periodontal support
136
Root surfaces can be diminished due to.. (2)
◦ Root resorption because of orthodontic treatment.
| ◦ Periodontal disease.
137
What do we look at when assessing edentulous spaces?
- length
- shape of the space
- shape of edentulous gap
- location of the space
- prosthetic space
138
Assement of the edentulous space will determine... (3)
- Number of abutment teeth used
- Type of pontic
- Bridge biomechanics
139
What affects bridge biomechanics? (3)
- Alloy used
- Thickness of the pontics
- Type of connector
140
Whats the relationship between load and length of edentulous space?
Longer space = greater the load
141
What is the prognosis of a bridge if 1 tooth is missing?
Very good prognosis
142
What is the prognosis of a bridge if 2 teeth are missing?
Good prognosis
143
What is the prognosis of a bridge if 3 teeth are missing?
Unfavorable prognosis
144
What is the prognosis of a bridge if 4 teeth are missing? (3)
Not indicated
Use implants or RPD
*exception: lower incisors
145
What causes failure of long bridges?
- Periodontal ligament overload.
- Failure of the materials.
- Misfit at distal margins.
- Biomechanical failure ( excess of lever or torque)
146
What is the prognosis of a bridge if the edentulous space is straight?
More favorable
147
What is the prognosis of a bridge if the edentulous space is curved? (3)
More unfavorable
- ex. upper front teeth
- may require using more teeth in the bridge
148
What type of pontic do you use if the edentulous ridge is normal (2)
- Modified ridge lap
| - Conical
149
What is a normal edentulous ridge?
Convex and no alot of bone loss
150
What type of pontic do you use if the edentulous ridge is thin but still convex?
Conical
151
What type of pontic do you use if the edentulous ridge is flat and wide?
- oval pontic (higher estheics)
| - Can be done with provisionals or surgically
152
What type of pontic do you use if the edentulous ridge has defects?
May need surgery to modify it
153
What is siberts class I
Class I: horizontal, width loss
154
What is siberts class II
vertical, height loss
155
What is siberts class III
Combination
156
If the edentulous area is maxillary, the occlusal load will...
tend to spread abutment teeth
157
If the edentulous area is mandibular, the occlusal load will...
tend to gather abutment teeth
158
What is more favorable, a maxillary or mandibular abutment space? (2)
Mandibular
| - better bone quality and better support
159
Edentulous space vs prosthetic space? (4)
- sometimes the edentulous space will be invaded
- extrusion on the antagonist
- mesial migration of the adjacent
- some previous treatment might be needed
160
How does the occlusal load affect a bridge?
WIll bend the bridge towards the ridge
161
What happens if the bridge bends towards the ridge? (3)
- tension over retainers => torque over abutments
- tends to separate retainer and abutment
- lever effect on curved edentulous spaces - can luxate teeth
162
Occlusal forces over a bridge can cause: (4)
- deflection
- torque over abutment
- lever arm, increaed effect over anterior
- luxation
163
What factors influence how much a bridge bends?
- length of the bridge
- thickness of the bridge
- curvature of the bridge
164
How does the length of a bridge effect how much it bends?
- Bending is directly proportional to the cube of the length (the dentulous span)
- longer=bendier= more risk of failure
165
How does the thickness of a bridge effect how much it bends? (3)
* The thickness will reduce the degree of the deflection
* Occluso-gingival thickness is the one that matters.
* Inversely proportional to the cube of the thickness.
166
How do you minimze torque over abutments? (4)
* Thicker pontics occluso-gingivally
* More rigid alloys ( Ni-Cr, Zr)
* Using more than one abutment tooth.
* thicker framework of the pontic
167
How do thicker framework of the pontics minimize torque over abutments for PFM crowns?
gingival or occlusal surface of the pontic made of metal
168
What to remember about thicker pontics minimizing torque over abutments?
Modifying the antagonist arch if necessary
169
How do more rigid allows minimize torque over abutments?
- Predominantly base alloys more rigid than:
- Noble alloys more rigid than:
- High noble alloys.
170
When should you use more than one abutment to minimize torque? (3)
- Esp when abutment doesnt have proper crown-to-root ratio
- Teeth further away from center suffer more torque
- conditions of secondary abutment are equal to primary
171
What forces does the secondary abutment have to support?
Must support tensile forces when the pontic flexes
172
Characteristics of the secondary abutment ? (4)
* Crown-to-root ratio: equal or bigger than the 1º
* Bone support: equal or bigger than the 1º
* Periodontal health: better or equal
* Retentive capacity: higher or equal
173
Embrasures between retainers on bridges must allow...
Correct hygiene
174
Why is the curvature of the arch important for a bridge??
- has an effect on the stress
175
When does a bridge have more risk of torque with the curvature of the bridge? (3)
- When the pontics are away from the line that joins the retainers
- produces lever action over the abutment
- the longer the lever arm, the more torque and luxation
176
How do you replace upper incisors in a bridge? (2)
- Pronounced curvature
| - to offset torque: gain retention on the opposite direction of the lever arm
177
What are the different bridge options based on what teeth are missing? (3)
- Simple
- Complex
- Special
178
When do you use a simple bridge?
- Replace only one tooth
| - both incisors or both premolars missing
179
What type of bridge do you use if the first premolar is missing? (4)
- Simple bridge
- use 3 & 5 as abutments
- Group function
* cantilever could be used but its not recommended
180
What type of bridge do you use if the second premolar is missing?
- simple bridge
181
What type of bridge do you use when the central and lateral incisors are missing?
Simple bridge:
- Maryland bridge
- Conventional bridge
Complex bridge
182
What type of bridge do you use when the premolars are missing?
Simple bridge
183
What type of bridge do you use when the second premolars and first molar are missing?
Simple bridge
184
What is a complex bridge?
- Two or more pontics
| - in a more committed location
185
Why are complex bridges more demanding? (3)
- toughness of retainers
- abutments
- periodontal support
186
What type of bridge do you use when replacing lower incisors?
- Complex bridge (four pontics)
187
In which type of bridge can you use a 3rd molar as an abutment?
- Complex bridges
Problematic b/c:
- incomplete eruption
- short & fused roots
- mesially inclined
188
When do you choose a secondary abutment in complex bridges?
- All the abutments must have the same retention.
- Also when there is a reduced periodontal support.
- They have to support a certain amount of flexes depending on the forces applied over the pontics.
189
What bridge do you use when a canine is missing?
- Complex bridge
- difficult because of canine guidance
- group function occlusion
- use both incisors as abutments and 1st premolar
190
What bridge do you use when a lower central and lateral incisor is missing?
Complex bridge
191
What bridge do you use when the upper central incisors are missing?
Complex bridge
192
What bridge do you use when the first and second premolars are missing?
Complex bridge
193
What bridge do you use when second premolars and first molar are missing?
Complex bridge
194
What bridge do you use when the lateral incisor and canine are missing?
- Complex bridge
- 3-4 abutment teeth
- group function
195
What bridge do you use when more than 2 upper incisors are missing?
Complex bridge
196
What bridge do you use when both premolars and first molar are missing? (4)
Complex bridge
- only if abutments are in perfect condition
- canine guidance
- rigid alloy (Ni-Cr)
197
What is a special bridge?
- has an intermediate abutment
198
What is an intermediate abutment
- There are two spaces next to a tooth
| - abutment suffers more
199
It is important that intermediate abutments are...
Periodontically sound
Have lots of healthy tooth structure
200
Do you use interlocks on special bridges?
Used to use them, not any more
201
Special bridges and inclined abutment teeth? (5)
- Specially lower 2nd molar.
- Very difficult to get a common path of insertion.
- Endo post might be needed
- Ortho treatment.
- Telescopic crown.
202
What bridge do you use if a canine and one other tooth is missing?
- Special bridge
| - Group function
203
What bridge do you put if a canine and 2 teeth are missing?
No bridge, RPD or implants
204
When can you use a cantilever bridge? (4)
* special bridge
- upper lateral incisor
- 1st premolar missing
- first molar missing
205
Upper laterial incosr and cantilever bridges?
- Lateral incisor shouldn't participate in canine guidance
206
First molar missing and catilever bridges?
Avoid
| if no other options, then reduce it MD
207
Do we splint special bridges?
Avoid whenever possible
- hinders hygiene
- all treatment can be committed because of one tooth
208
When should we splint special bridges? (3)
- periodontal reasons
- tooth with very short clinical crown
- combined prothesis
209
Full mouth rehabilitations and splinting?
Splinting as one single bridge should be avoided.
◦ It’s difficult to achieve a good fit.
◦ Hindered hygiene.
◦ All the treatment can be committed because of one tooth.
◦ Mandible bending movement.
210
Full mouth rehabilitations and special bridges?
Divide bridges into sectors:
- anterior on one side
- posteriors on other
