Bridges Flashcards
Discuss the survival rate of bridges
Bridges are most likely to fail in the first 2 years after treatment. They then have an 80% success rate for 5 years and an 80% success rate for 10 years.
Compare adhesive and conventional bridges
Adhesive bridges are held on using little wings on the palatal surface
Conventional bridges are held on using crowns.
List some indications for using bridges
Better function and stability
Appearance
Speech
Systemic disease (i.e. epilepsy- if patient has seizure then they could choke if it is a removable appliance)
Big teeth (larger area is better for the wings)
Favourable abutment angulations
Favourable occlusion- heavy occlusal contacts on the bridge= greater risk of fracture.
Why does the patient’s dental health contraindicate the use of bridges.
If patient has bad dental health then the bridge is more likely to fail:
Poor oral hygiene
High caries rate
Periodontal disease.
The patient is missing multiple teeth
Why does this impact the choice of a bridge in the treatment plan?
You want to replace as few teeth as possibe- A longer bridge is likely to flex and more likely to break.
Why does the patient’s ridge form and tissue loss impact the choice of a bridge in the treatment plan?
Bridges only replace the tooth, so a dentrue may be more suited for the aesthetic.
What is the abutment tooth?
The tooth that serves as an attachment for the bridge.
What is the pontic?
The fake tooth that is suspended from the abutment tooth.
What is the retainer?
The Extracoronal or intracoronal restorations that are connected to the pontic and cemented to the abutment tooth .
What is the connector?
The part that connects the pontic to the retainer.
What is the edentulous span?
The area between the teeth that is being replaced.
What is the saddle?
The area of the edentulous ridge (Over which the pontic will lie)
What is the pier?
An abutment tooth which stands between and is supporting two pontics- each pontic being attached to a further abutment tooth (found in larger bridge designs)
What is a unit in the bridge?
A part of the bridge
e.g. a 3 unit bridge= retainer/pontic/pier.
Compare a fixed- fixed bridge to a cantilever bridge
A fixed-fixed bridge has a retainer on each side and a pontic in the middle.
A cantilever bridge only has a retainer on one side of the pontic.
Where is a fixed fixed bridge used?
Posterior teeth .
Where is a cantilever bridge used?
Anterior teeth.
What do we look for when examining a patient before prescribing a bridge?
Abutment teeth - are they appropriate )
Occlusion (any heavy occlusal contacts)
Periodontal- the bone levels around the area.
Radiological- is there any periapical pathology?
Patient’s oral hygiene - are they able to look after the bridge.
How can we use study models to aid the treatment planning of a bridge?
- We can use a diagnostic wax up to give an indication of the final aesthetic result.
- We can mount it on a semi-adjustable articulator with facebow registration (especially if using canines)
When selecting an appropriate abutment tooth what are we looking for in the radiograph?
- Root configuration- big thick multirooted teeth are more likely to withstand the force down the abutment tooth.
- Angulation/ rotation of the abutment.
- Periodontal health- We need good bone support around the abutment.
- Quality of endo (Is RCT good enough? Is there a core that needs removed/rebuilt)
- Crown to root ratio (length o fcoroanl tooth to root in bone) - want 2;3
When selecting an appropriate abutment tooth-what are we looking at clinically ?
Is there remaining tooth structure present?
Is there a good surface area for bonding?
How is the enamel quality?
Are the supporting tissues healthy/ free of inflammation?
Name and compare the types of resin bonded bridge?
Direct- Used in an emergency and produced chairside
Indirect- Tooth is prepared and then impressions are taken. The bridge is made in a lab and cemented in at a later appointment.
What materials can be used for the wing of an indirect resin bonded bridge?
Cobalt chrome wing or all ceramic.
How do we create a direct resin bonded bridge.
We try and use the patients natural tooth as the pontic
- We cut off the root and remove the pulp tissue
- We then close the hole into the pulp chamber with composite.
- Etch the contact point of the recently extracted tooth.
- etch the contact points of the adjacent teeth.
- Prime and bond the contact areas we have etched.
- Use composite to stick the bridge into place.
Explain why fixed fixed bridges aren’t used for anterior teeth?
The divergent paths of the anterior teeth means that there are different occlusal forces going in different directions. This makes the restoration more likely to debond making space for the ingress of bacteria and caries.
How does a fixed moveable bridge work?
A crown goes on 1 tooth and sits on the path of insertion. It contains a slot that corresponds with the 7s path of insertion. The slot allows the other part of the bridge to slot together connecting it.
What are some considerations we have with chosing a pontic shape?
Cleansibility- it should be smooth with a highly polished or glazed surface.
The join between metal and porcelain should not be under the occlusal force.
Strength- Longer the span the greater the thickness we require to withstand the occlusal forces.
Surfaces-
The occlusal should resemble the surface of the tooth it is replacing. it should be narrower if possible to enable cleaning.
We should have sufficient occlusal contact.
Approximal surface- the connector should be ideally about 2mm for adequate strength.
The ridge surface is dependent on pontic choice.
Identify this pontic shape and discuss it.
This is a wash through pontic.
This is used in the lower molar area
It provides an extra biting surface.
It is used for function not aesthetics.
Identfiy this pontic design and discuss it?
Dome pontic
Used in lower incisors/ premolars or upper molar areas.
Top of pontic is tooth shaped and aesthetic but lower 1/3 isn’t to be more cleansable.
This is a poor aesthetic if gingival 1/3 of the tooth is visible.
Identify this pontic and discuss it.
Modified ridge lap pontic.
This makes the tooth look good from a facial perspective.
The lingual aspect is created to be more cleansible but it is more likely to get food packed in that area (The packed food can be cleaned back out)
Identify this pontic and discuss it?
This is the ridge lap pontic.
This has the greatest contact with the soft tissues.
There is less food packing than the modified ridge lap- It presses on the soft tissues causing blanching.
If a patient has bad OH there can be plaque accumulation under the fitting surface causing inflammation.
