Conventional bridges Flashcards
What is a fixed dental prosthesis?
Any dental prosthesis that is luted, screwed or mechanically attached to natural teeth, tooth roots and or dental implant abutments providing primary support for dental prosthesis
Name the 3 parts the components of a fixed bridge is split into
- Abutment
- Pontic
- Retainer
What is an abutment
The part of a structure that directly receives the pressure
The abutment can be natural tooth or a dental implant
What is a Pontic
An artificial tooth on a fixed dental prosthesis that replaces a missing natural tooth, restores its function and usually fills the space previously occupied by the clinical crown
What is a retainer
The part of the bridge which is cemented to the abutments
What forms can a retainer take?
- Crown
- 3/4 Crown
- Metal wing
- Inlay/ onlay
Name the different types of abutments
- Single abutment
2. Double abutment
Name the different types of Pontic designs
- Modified ridge lap
- Ovate
- Sanitary
- Ridge lap
Which of the different poetic designs is the most common?
Modified ridge lap
What is a ridge lap Pontic
When the Pontic is directly contacting the ridge both bucally and lingually
What is a modified ridge lap pontic
When the Pontic is only in direct contact with the ridge bucally
What is a sanitary Pontic
When there is not contact between the ridge and the Pontic
What is an ovate Pontic
When there is point contact between the Pontic and the ridge
What is the main purpose of having different pontic designs?
To make the bridge more hygienic
Why is the modified ridge lap pontic the most common
As it gives you the aesthetic where there is no gap bucally between the tooth and gingivea and it is also easy to clean
Which of the pontic designs is the most hygienic?
The sanitary pontic as there is space under the pontic for cleaning
BUT this is the least aesthetic
Which of the pontic designs is the most aesthetic?
The ovate pontic
BUT you have to perform soft tissue surgery to prepare the site so only placed where aesthetics are important (anterior teeth)
Name the different types of conventional bridges
- Conventional fixed-fixed bridges
2. Conventional cantilever bridges
What is a conventional fixed-fixed bridge
A fixed dental prosthesis in which the pontic is retained and supported by 2 abutments, on either side of the pontic
What is a conventional cantilever bridges
The pontic is retained by a conventional crown, inlay or onlay
List some indication for conventional bridgework
- Heavily restored abutments
- Well motivated patients with excellent plaque control
- No active caries lesion
- Stable periodontist
- Patient is able to clean and maintain the bridge work
- Small edentulous spaces
- Replacement bridge work
What do we mean by conventional?
The abutment has a conventional prep eg a crown, inlay or onlay
List some contra indication for conventional bridgework
- Unrestored abutment
- Poorly motivated patient
- Active caries
- Active periodontitis
- Poor manual dexterity (won’t be able to clean bridge)
- Large edentulous spaces
- Contact sports player
Why is being a contact sports player a contra indication for conventional bridgework?
If they have a fixed bridge and get hit the abutment teeth can fracture and bridge will be unsuccessful
Instead wed prefer to give a denture as they can remove their when playing the sport
List the teeth that make ideal bridge abutments
1s, 3s and 6s
What qualities in a tooth make it an ideal abutment>
Teeth with:
- Long roots
- Multi rooted teeth
- Sufficient tooth structure and height
Describe teeth that are unsuitable for abutments
- Heavily restored teeth
- Endo treated teeth
- Teeth with posts
What other types fo bridges are there apart from conventional bridges?
Resin retained bridges
Give examples of resin retained bridges
- Resin retained cantilever bridges
What is a resin retained cantilever bridge?
When the pontic is retained by a metal retainer relaying mainly of the cement and maximum abutment coverage
List some indications for a resin retained bridge
- Sound, unreported abutment
- Well motivated patient with excellent plaque control
- No active caries lesion and stable periodontium
- Patient is able to clean and maintain bridgework
- Small edentulous spaces
List some contra indication for resin retained bridges
- Heavily restored abutments
- Lack of clinical height in the abutment teeth
- Poorly motivated patients
- Patients with active cares or periodontitis
- Poor manual dexterity so won’t be able to clean bridge
- Large edentulous spaces
- Contact sports player
- Patients with bruxism and parafuncitonal habits
How do we prepare abutment teeth for a resin retained bridge
In most cases no preparation is needed
This is to allow maximum bonding to enamel layer
When might you need to prepare the abutment tooth for a resin retain bridge?
When you need to create space or if the occlusion won’t permit the bridge to fit
BUT limit prep to enamel only
List some design features for a resin retained bridges
- Covers maximal surface area of the abutment teeth
- Use rigid non precious metal wing retainers (0.7-0.8mm)
3, Use cantilever design for adhesive bridgework and keep the pontic out of excursive contacts
What should we try to cover when designing a resin retained bridge
Try and cover the maximum surface area of the abutment teeth
Describe the ideal wing retainer we would use for a resin retained bridge
Rigid non precious retainers of at least 0.7-0.8mm thickness
Is it acceptable to bond resin retained bridges slightly high? Why?
Yes it is acceptable as eventually the posterior teeth will eventually over erupt correcting the bite
Why might we bond the resin retained bridge slightly high?
To maximise:
- Retention of the bridge
- Coverage
- Retention to enamel
Which type fo design should we aim for when creating adhesive bridgework
Cantilever design
Occlusally how should a resin retainer bridge fit in the mouth
You want to aim to have light contacts in ICP on the pontic
You want to have no contact on the pontic during lateral or protrusive excursions
Why do we to have no contact on the Pontic during excursion?
Do make sure bridge doesn’t debond
Which teeth make the ideal abutment for a resin retained bridge?
Canines and molars
Why are canines and molars ideal abutments fro a resin retained bridge?
- They are large
2. There is a lot surface area for you to cover to maximise retention
What do you want to avoid in a resin retained bridge
A fixed- fixed design
What is a fixed fixed resin retained bridge
When you use 2 abutments (one on each side of the saddle). 2 metal wings extend medially and distally from the pontic to retain the artificial tooth
Why do we want to avoid making a fixed fixed resin retained bridge
When these bridges fail it is quite catastrophic as they fail on the wing-tooth interface. But as there is a second abutment you dont realise that the bridge has failed until much later.
A gap can form at the tooth-long interface which can lead to caries formation
What do we mean by cantilevered?
The pontic is retained and supported only on ONE END by one or more abutments
What is a cantilever bridge?
A fixed dental prosthesis in which the pontic is cantilevered
Talk through the steps of making a conventional bridge
- Take a primary impression
- Diagnostic wax up on study model
- Abutment preparation and master impression in silicone
- Temporise the tooth until next appointment
- Bridge construction while mounted on an articulator
- Bridge trial and cementation
What are some design considerations we need to make when making a conventional bridge?
- Occlusion: keep the pontic in light contact in ICP an Don contact in lateral/protrusive movements
- Try and share the bridge occlusal guidance with the natural teeth if possible
Talk through the steps of making a resin retained bridge
- Take a primary impression
- Get a diagnostic wax up on study models
- Take a master impression with silicone
- Bridge construction while mounted on an articulator
- Bridge trial and cementation
What are some design consideration we need to make when making a resin retained bridge
- Occlusion: keep the pontic with light contact in ICP and no contact in lateral/ protrusive movements
- Share the bridge occlusal guidance with natural teeth if needed
- Discuss wax up with patient specially in anterior bridgework
- Explain to the patient that metal wings might show through abutment
What should you tell a patient who is thinking of having a resin readied bridge
Tell the patient that the metal wing may show through the abutment
Are fixed-fixed bridges common?
No they are not contemporary practice
What are fixed fixed bridges no contemporary practice?
As it it destructive and long term complication are mostly catastrophic including caries and deontic failure of the abutment teeth
When are fixed fixed bridge usually used
Mostly used as a replacement option of an old bridge if abutments are still sound
What complications can arise when placing a conventional bridge
- Pulp can die
2.
What is the 10 year pulp survivability under a single ceramic crown
84.4%
What is the 15 year pulp survivability under a single ceramic crown
81.2%
What is the 10 year pulp survivability under an abutment MCC
70.8%
What is the 15 year pulp survivability under an abutment MCC
66.2%
Why might a crown or bridge fail?
- Endodontics
- Endodontic and debond
- Debond of retainer
- Aesthetics
- Prosthetics
- Fracture of porcelain
- Root caries
- Pain
- Root fracture
Name the most common cause if bridge failure
The abutment teeth needing endodontic treatment (53.3%)
What is the survival rate for a conventional cantilever
5 Years 91%
10 years 81.8%
What are the main complications surrounding conventional cantilevers
Caries risk
Endodontic risk
Loss of retention
What is the survival rate for conventional fixed fixed bridges
5 years 94%
10 years 92%
What are the main complications surrounding conventional fixed fixed bridges
Caries risk
Endo risk
What is the survival rate for resin retained cantilever bridges
5 years 80.8%
10 years 80.4%
What are the main complications surrounding resin retained cantilever bridges
Debonding
