Bridgework Flashcards
What is a dental bridge?
Prosthesis which replaces a missing tooth/teeth, and is attached to one or more natural teeth or implants.
Contra indications of bridgework?
Poor pt cooperation
Medical history - metal allergy
Poor OH
High Caries rate
Periodontal disease
Large pulp horns in young patients ‘conventional bridge’
High possibility of further tooth loss in the arch
Poor abutment quality / poor prognosis
Length of a span of bridge is too long
Poor ridge form / tissue or bone loss
Tilting and rotating of teeth
Largely restored dentition
Periapical status - no active endodontic or pulpal disease
Define abutment and Pontic
Abutment = tooth which serves as an attachment for a bridge
Pontic = tooth that is suspended from the abutment tooth / teeth
Define retainer with regards to bridgework
Define connector
Retainer = Extracorornal or intracoronal restorations that are connected to the Pontic, and cemented to the prepared abutment teeth
Connector = component which connects the Pontic to the retainer
Define a pier and a unit
Pier = An abutment tooth which stands between, and is supporting two Pontics. Each Pontic being attached to a further abutment tooth
Unit = either a retainer or a Pontic
What is a fixed - fixed bridge?
Bridge retainer either side of a Pontic
Retainer - Pontic - retainer
Can be adhesive/resin retained or conventional
What retainers are used for conventional and what are used for adhesive bridges
Conventional - crowns
Resin retained - metal NiCr or CoCr retainers
Advantages of a fixed fixed bridge
Robust
Maximum retention and strength
Splinted abutments can help perio cases
Can be used in longer spans
Simple lab work
Disadvantages of fixed - fixed bridgework
Large tooth preparation needed
Prep must be parallel and minimally tapered
Common path of insertion needed for all abutments
What is a cantilever bridge?
Can be fixed -fixed, or resin retained / adhesive
Retainer at only one end
Advantages of cantilever bridge?
More Conservative than fixed - fixed
Straightforward lab work
No need to ensure tooth preparations are parallel
Disadvantages of cantilever bridges
Less retentive than fixed fixed
Must be rigid to avoid distortion
Smaller span
Mesial cantilever is preferred
What is a fixed - moveable bridge?
Rigid connector distal to Pontic,
Moveable connector mesially, to allow for some vertical movement at the mesial abutment tooth
Advantages of fixed - moveable bridge?
Preps don’t require common path of insertion
More conservative
Allows minor tooth movement
Disadvantages of fixed - moveable bridges
Limited edentulous span
More complex labwork
Possible difficulty cleaning between moveable joint
Can’t construct a provisional
What is a hybrid bridge?
One end = conventional
One end = resin retained / adhesive
What is a spring cantilever bridge?
Pontic is attached to the end of a metal arm that runs across the palate, to a rigid connector on the palatal side of a retainer
Advantages of conventional spring cantilever bridge?
Useful if there is spacing between upper incisors
Useful where adjacent teeth are unrestored
Where a posterior tooth would provide suitable abutment - e.g. already has a large restoration or a crown
Disadvantages of conventional spring cantilever
Only used for maxillary incisors
Difficulty cleaning behind palatal connector on the retainer
May irritate palatal mucosa
Difficult to control movement of Pontic due to spring in the metal arm and displacement of soft tissues
How should an abutment tooth be evaluated?
Must be able to withstand forces previously directed at missing teeth
Supporting tissues should be free of inflammation, and healthy
Crown : root ratio
- optimum ratio is 2:3, minimum is 1:1
On an abutment, what should be considered when evaluating it for use in a bridge?
Root configuration
Angulation and rotation of the abutment
Periodontal health of the abutment
Occlusion of the abutment
Quality of enamel
Risk of pulpal damage (high horns in younger pt)
What is the function of the Pontic?
Restore function
Restore aesthetics
Stabilise occlusion
What are the main considerations when selecting a Pontic design?
Cleansability
- smooth and highly polished
- easy to clean
- free of plaque trap surfaces
Appearance
- tooth like
- correct shade
Strength
- longer the span = greater the thickness needed to withstand occlusal forces
What is a wash through Pontic?
No contact with soft tissue
Functional rather than aesthetic
Consider for lower molars
What is a dome Pontic?
Bullet-shaped or torpedo
- useful for lower incisor or premolars
- useful for upper molars
Poor aesthetics if gingival 1/3 of tooth visible
What is a modified ridge lap Pontic?
Buccal surface looks as much like a tooth as possible
Cut away lingual surface
Problems with food packing on lingual surface
Good for maxillary incisors
What is a ridge lap Pontic?
Greatest contact with soft tissue
Can be cleansed if designed properly
Less food packing than modified ridge lap
Must not bleach tissue or displace soft tissue too much
What are the first steps for producing a bridge after all examinations have been done?
Produce mounted study models, with a vacuum formed stent.
- allows checking of reduction and ability to produce a provisional bridge
What material is used to bond conventional metal bridges / metal ceramic?
GI luting cement
RMGI luting cement - e.g. relyX
What is used to bond resin bonded bridges?
Panavia 21
Anaerobic dual cure resin cement
What is used to bond all ceramic bridges?
NEXUS dual cure resin cement
Why are distal cantilevers avoided? When may one be considered to be ok?
Concern occlusal forces on Pontic will produce leverage forces on abutment tooth
Premolar abutment where opposing arch is edentate or a denture
What is a LAVA 3M ESPE material in bridges?
Milled zirconium oxide frame
Feldspathic porcelain overlying
Good aesthetics and can withstand occlusal forces
Similar reduction to MCC
Advantages of using resin bonded bridgework?
Minimal to no preparation of the tooth
Can be used as a provisional restoration e.g. hypodontia patient who should get implants, but when older
No anaesthetic needed
Less costly and less surgery time
If it fails, less destructive than other alternatives
Disadvantages of RBB
Rigorous clinical technique - moisture control is essential
Metal can shine through the tooth - translucent incisal edge
- do not overextend retainer
Chipping of the porcelain Pontic
Can debond, once fallen off, higher chance of future debonding
Occlusal interferences
- these usually disappear within 14 days through axial tooth movement to restore occlusion
No trial period possible
Indications for RBB
Young teeth - less destructive option
Good enamel quality
Large abutment tooth surface area
Minimal occlusal load
Single tooth replacements
Simplify partial denture design
Contraindications of RBB?
Poor quality enamel
Long spans
Excess hard or soft tissues
Heavy occlusal forces - bruxism
Poorly aligned, tilted or spaced teeth
Contact sports? Possible contraindication.
What should cross my mind when deciding if a patient is suitable for bridgework
Is it appropriate, are there other treatment options?
I should take care if patient insistent on bridgework. Explain what it is, and what they can and cannot do.
Look at: abutments, occlusion and aesthetics, para-functional habits etc.
Can patient maintain the oral hygiene for complex work?
What are direct and indirect RBBs?
Direct - emergency situations, tooth xla immediately and pt cannot leave with edentulous space
Indirect - prosthesis is made in a lab and is cemented at another appt
How might one manufacture a Pontic for a direct RBB?
Ideally use patients existing tooth, cut the root off and clear pulpal chamber.
Can use an acrylic denture tooth
Prefab polycarbonate crown
Matrix in tooth shape, filled with composite
How can the patients existing tooth be bonded to the adjacent as a direct Pontic?
Etch and bond the contact points of the Pontic and the abutment teeth
‘Splint’ teeth with composite temporarily
Complete long term treatment
What areas are fixed - fixed and cantilever usually used?
F-F in posterior teeth
C in anterior teeth
What prep may need to be done for a RBB?
180 degree ‘wrap around’ prep
Rest seats - posterior teeth
Cingulum rest - anterior teeth
- both can help with locating the correct position on the tooth for cementation.
Proximal grooves can aid mechanical retention
Supra gingival chamfer finish line - 0.5mm supragingival
Prep remain in enamel
How thick typically is the metal retainer for an anterior RBB?
0.7mm thick
If you have prepped a tooth for a RBB and pt is getting sensitivity, how can this be treated?
Consider duraphat sensitivity toothpaste
Layer of DBA over exposed dentine
Fix bridge ASAP, 2 weeks most likely
- risk over eruption or tooth movement
What should be done post cementation?
Check occlusion
- heavy contact on Pontic, adjust them
- heavy contact on retaining wings - axial tooth movements should solve
Show pt how to clean under and around Pontic
- superfloss - thin bit under Pontic, pull and then sweep under
- interdental brushes
What are the typical survival rates for resin bonded bridgework?
80.8% at five years
80.4% at ten years
King et. Al
Most likely to fail in first two years
