Bridgework Flashcards
what do you do with a missing tooth/teeth?
- No treatment/Leave space
- Replace tooth/teeth
- Close space (Orthodontics)
what are reasons for treating tooth loss?
- aesthetics
- function
- speech
- maintenance of dental health
what are tooth replacement options?
- denture
- bridgework
- implants
what is a bridge?
A prosthesis which replaces a missing tooth or teeth and is attached to one or more natural teeth (or implants)
what is difference between a fixed partial denture and bridge?
a fixed partial denture replaces soft tissue and bone
what are some indications for bridgework?
GENERAL
- Function and stability
- Appearance
- Speech
- Psychological reasons
- Systemic disease e.g. epileptics
- Co-operative patient
LOCAL
- big teeth
- heavily restored teeth
- favourable abutment angulation
- favourable occlusion
what are contra-indicaations for bridgework?
GENERAL
- Uncooperative patient
- Medical history contra-indications
- Poor oral hygiene
- High caries rate
- Periodontal disease
- Large pulps (conventional bridge)
LOCAL
- High possibility of further tooth loss within arch
- Prognosis of abutment poor
- Length of span too great
- Ridge form and tissue loss
- Tilting and rotation of teeth
- Degree of restoration (how much of tooth is left after preparation)
- Periapical status
- Periodontal status (bone loss)
what is an abutment?
A tooth which serves as an attachment for a bridge
what is a pontic?
The artificial tooth which is suspended from the abutment teeth/tooth
what is retainers?
The extracoronal or intracoronal restorations that are connected to the pontic and cemented to the prepared abutment teeth
what are the connectors?
Component which connects the pontic to the retainers/retainer
what is edentulous span?
Space between natural teeth that is to be filled by a bridge or partial denture
what is saddle?
Area of the edentulous ridge over which the pontic will lie
what is a pier?
An abutment tooth which stands between and is supporting two pontics, each pontic being attached to a further abutment tooth
what is a unit? and for example what would a bridge with 2 retainers and one pontic be?
Either a retainer or a pontic
- e.g. A bridge with two retainers and one pontic = 3 unit bridge
what are types of bridge designs?
conventional (means commonly used)
- fixed-fixed
- cantilever
fixed moveable bridge
hybrid bridge
spring cantilever bridge
what is a fixed-fixed bridge?
This type of bridge has a retainer at each end with a pontic in the middle joined by rigid connectors.
what can a fixed-fixed be?
- Adhesive/resin retained
- Conventional
what is a cantilever bridge?
This type of bridge has a retainer (or retainers) at one side of the pontic only
what cana cantilever bridge be?
- Adhesive/resin retained
- Conventional
what are advantages of resin bonded bridgework?
- Minimal or no preparation
- No anaesthetic needed
- Less costly
- Less surgery time
- Can be used as a provisional restoration
- If fails - usually less destructive than alternatives
what are disadvantages of resin bonded bridgework?
- Rigorous clinical technique
- Metal shine-through
- Chipping pocelain
- Can debond (High chance of it debonding again)
- Occlusal interferences
- No trial period possible
what are indications for resin bonded bridgework?
- Young teeth (Less destructive)
- Good enamel quality
- Large abutment tooth surface area
- Minimal occlusal load
- Good for single tooth replacement
- Simplify partial denture design
what are contraindications for for resin bonded bridgework?
- Insufficient or poor quality enamel
- Long spans
- Excess soft or hard tissue loss
- Heavy occlusal force e.g. Bruxist
- Poorly aligned, tilted or spaced teeth
- Contact sports?
when planning treatment what must you establish during history taking?
habits e.g bruxism
during a clinical exam for resin bonded bridge what do you exam?
- dynamic occlusal relationships
- periodontal
- radiological
what must you do with study models for resin bonded bridgework and what may you consider
- mounted on semi-adjustable articulator with facebow registration
- may consider diagnostic wax-ups
what must you consider when making a decision on treatment?
- Is bridgework appropriate? (Other options?)
- Take care if patient is insistent on bridgework
- Look at: (Abutment teeth, Occlusion, Aesthetics (including soft tissue contour))
- Can patient maintain this complex work? (Poor OH?)
what is important to check for with a resin bonded bridge in terms of occlusion?
Consider opposing dentition
- e.g. Contact points
- Over-eruption of opposing teeth
Is there a parafunctional habit?
- Bruxism (clenching and/or grinding teeth)
Look at dynamic occlusal relationships
- Clinically
- Mounted study models
- Consider diagnostic wax-ups
when to use a direct resin bonded bridge?
- Very useful in emergency situation
- If tooth needs to be extracted immediately
- If tooth has been lost traumatically
what do you ideally use when manufacturing a pontic?
the patient’s own tooth
what are alternatives to using patient’s own toot when manufacturing a pontic?
- Acrylic ‘denture’ tooth
- Polycarbonate crown
- Cellulose matrix filled with composite
for an indirect resin bonded bridge what do you need in terms of palatal/lingual coverage?
- Need generous palatal/lingual coverage
- Need good quality enamel
- Keep supra-gingival (Ideal 0.5mm )
- Care with coverage near incisal edge
(Enamel translucent (Grey shine through))
why do you need general palatal/llingual coverage?
Greater surface area of enamel covered leads to Greater bond
when would you do cantilever or fixed-fixed?
anterior - generally cantilever
posterior - generally fixed-fixed
what are considerations in regards to existing restorations in abutment teeth?
- firstly need sound enamel
composite - ok but might need to consider replacing prior to prep
amalgam - compromised bond to chemically cured composite cement so consider replacing
if preparation is required what kind of prep do you do?
- 180 degrees wrap around preparation
rests
-anterior- cingulum rests
- posterior - rest seats
what is supra gignival chamfer finish line for bridge?
0.5mm
what are types of preparation for bridges?
no prep
minimal prep
heavier prep
how do you do a minimal prep anterior preparation?
- Occlusal contact reduction,
- Cingulum undercut removal only
- Chamfer margin (0.5mm supra-gingival)
how do you do a heavier preparation anterior prep?
0.5mm palatal reduction(NOTE – metal retainer wing should be 0.7mm thick)
Cingulum rest
+/- Proximal grooves
Chamfer margin (0.5mm supra-gingival)
how do you do posterior preparation?
- Occlusal rests
- 180º wrap-around with chamfer finish line (0.5mm supra-gingival)
- +/- Proximal grooves
if prep is into dentine and tooth becomes sensitive in the temporary time what do you do?
Cover with layer of dentine bonding agent
why must you fit bridge as quickly as possible?
Minimise over-eruption and tooth movement
what is fit surace of retainer?
Cobalt chrome or nickel-chromium alloy (typically)
Sandblasted surface
- Micro-mechanical retention
- Aluminium Oxide - 50 microns
what is treatment of retainer?
try in
- fit and aesthetics
chairside micro-etching with 50 micron aluminium oxide particles (sandblast)
- should have been done by technician
clean retainer
- ultrasonic bath if required
- use ethanol to ‘degrasse’ if required (reduced surface tension)
apply chemically (or dual cure) cure composite luting cement just prior to placement of restoration after tooth treatment
how would you go about the treatment on the tooth prior to placing retainer?
- Prophylaxis
- Isolate with dental dam
- Etch tooth: 37% ortho-phosphoric acid (some preparations are 40%)
- Wash & dry
- Apply primer (A and B mixed together) for 30 seconds
- Air dry for 2 seconds
- No need to cure (unlike for direct composite restorations)
after treatment of tooth what do you do?
Fit retainer (coated with luting cement) to abutment tooth/teeth
Remove excess cement
Oxygen inhibitor (Oxyguard II) placed around cement margins for 3 minutes
- Wash off
what do you do post-cementation?
check occlusion
- confirm pontic does not have excessive occlusal forces applied
demonstrate to patient how to clean around and underneath the bridge
- superfloss
- interdental brushes
what is longevity for bridges?
5 years - 80.8 percent
10 years - 80.4 percent
what are advantages of a conventional fixed-fixed bridge?
- Robust design
- Maximum retention and strength
- Abutment teeth splinted together ? (Perio cases with mobile teeth)
- Can be used in longer spans
- Laboratory construction straightforward
what are disadvantages of a conventional fixed-fixed bridge?
- Preparation difficult (parallel tooth preparations needed)
- Preparation must be minimally tapered
- Common path of insertion for abutments
- Removal of tooth tissue (danger to pulp)
how many retainers can a cantilever bridge have?
- could have one or more as long as only on one end
what are advantages of a cantilever bridge?
Conservative design
- Compared to fixed-fixed conventional design
Laboratory construction straightforward
No need to ensure multiple tooth preparations are parallel
what are disadvantages of a conventional cantilever bridge?
- Short span only
- Rigid to avoid distortion
- Mesial cantilever preferred
what is a solution to fixed-fixed designs when abutment teeth are not parallel?
fixed moveable bridge
- retainers with separate paths of insertion the bridge is united by a moveable connector
what is a fixed-moveble bridge?
This type of bridge has a rigid connector usually at the distal end of the pontic and a moveable connector mesially
- Allows some vertical movement at the mesial abutment tooth
what are advantages of conventional fixed-moveable bridge?
- Preparations don’t require a common path of insertion
- Each preparation designed to be retentive independent of others
- More conservative of tooth tissue
- Allows minor tooth movement
- May be cemented in two parts
what are disadvantages of conventional fixed-moveable?
- Length of span limited
- Laboratory construction more complicated
- Possible difficulty in cleaning beneath moveable joint
- Can’t construct provisional bridge
what is a hybrid bridge?
one retainer is conventional preparation the other retainer is minimal preparation (adhesive/ resin retained/ resin bonded)
what is spring cantilever bridge?
One pontic attached to the end of a metal arm that runs across the palate to a rigid connector on the palatal side of a retainer
what are advantages of conventional spring cantilever bridge?
- Useful if spacing present between upper incisors
- Where adjacent teeth are unrestored
- Where a posterior tooth would provide a suitable abutment (i.e. already has a crown/large direct restoration)
what are disadvantages of conventional spring cantilever bridge?
- Can only be used to replace upper incisor teeth
- Difficult to clean beneath palatal connector
- May irritate the palatal mucosa
- Difficult to control movement of pontic, due to springiness of metal arm and displacement of palatal soft tissues
how do you evaluate abutment?
Must be able to withstand the forces previously directed to the missing teeth
Supporting tissues should be healthy and free of inflammation
- i.e. periapical disease and periodontal disease
Crown to root ratio
- length of tooth coronal to alveolar crest compared to length of root embedded in bone. Optimum ratio 2:3. (Minimum ratio 1:1)
Bridgework 3
what must be thought of when designing and planning bridges?
Minimal preparation or conventional preparation?
- i.e. Conservation of tooth tissue
Material?
Abutment evaluation?
Cleansability
- Bridges will fail if OH isn’t easily performed
Appearance/Aesthetics
- Confirm that the patient’s expectations are achievable
how to evaluate potential abutments?
- Root configuration
- Angulation/rotation of abutment
- Periodontal health
- Surface area for bonding & quality of enamel
- Risk of pulpal damage
- Quality of endodontics:
Re-root canal treatment? - Remaining tooth structure present?
- Core (Remove and rebuild?)
what is the function of the pontic?
- Restore appearance of missing tooth
- Stabilise the occlusion
- Improve masticatory function
what are considerations for pontic design?
Cleansability
- Should always be smooth, with highly polished or glazed surface
- Surface should not harbour join of metal and porcelain (if metal-ceramic design used)
- Embrasure space smooth and cleansable
Appearance
- Anteriorly - as ‘tooth like’ as possible
- Posteriorly - may compromise
Strength
- Longer the span - Greater the thickness required to withstand occlusal forces
what are surfaces of pontic?
Occlusal surface
- Resemble surface of tooth it replaces
- Narrower if possible to enable cleaning
- Should have sufficient occlusal contact
Approximal surface
- Connector: strength
- Embrasure: space
Buccal & lingual surface
Ridge surface
what are types of pontic designs?
- wash through
- dome shaped
- modified ridge lap
- ridge lap pontic (full saddle pontic)
what are types of materials for conventional bridges?
- All metal
Gold
Nickel/Cobalt chromium?
Stainless steal - Metal ceramic
- All ceramic
Zirconia
E.g. LAVA and Procera®
Lithium disilicate
E.g. - E.max - Ceromeric
BelleGlass™
Vectris®
Targis® Vectris®
when would you especially use gold material for conventional bridges?
lower posterior area
what is most common material for conventional bridges?
metal ceramic
what is properties of LAVA?
- 3-4 unit fixed bridge (max span)
- withstand occlusal forces
- good aesthetics
- similar reduction to MCC
what are properties of zirconia?
- preps on casts scanned (straumann)
- milled
- +/- feldspathic (layer) porcelain on top
what are properties of implant retained bridges?
- large span bridges
- either screw retained or cement retained
what should you consider before prep of conventional bridgework?
must have mounted study models
consider diagnostic wax-up and custom impression tray
what must you request from lab for preparation of conventional bridgework?
to construct a vaccum-formed stent
what does a vaccum formed stent allow during construction of bridge?
- checking of reduction during tooth prep
- construction of provisional bridge
what must you aim for when doing a conventional bridgework prep?
parallelism of tapered surface of each prep
what is parallelism of tapered surface of each prep?
it is doing same side of both abutments one after other instead of whole abutment then other abutment for example
what is process of prep of conventional bridgework?
- select shade
- lab made stent or make pre-op putty impression for provisional bridge
- occlusal or incisal reduction
- seperation of teeth
- paralelism of tapered surface of each prep
when must you consider parallelism during prep?
- for fixed-fixed conventional bridge
- requires 2 or more teeth to be prepared in a manner to provide a common path of insertion - increased retention
- no undercuts
why is it important to provide a good common path of insertion?
to increase retention
when must you consider retentive features during prep of conventional bridge work? and what kind of retentive features?
if short clinic crown height or overtapered
- slots
- grooves
after parallelism what is next stage of prep?
- Confirm parallelism
- Consider retentive features if short clinical crown height or overtapered
- Construct provisional bridge
- Make impression and occlusal registration
- Temporarily cement provisional bridge
- Demonstrate cleaning with Superfloss™
- Write/draw prescription for technician
what do you use for definitive cementation for all metal conventional bridge work and metal ceramic bridgework?
- aquacem (GI luting agent)
- RelyX luting (RMGI luting agent)
what do you use for a definitive cementation for an adhesive/resin bonded/resin retained bridgwork?
- panavia 21 (anaerobic duel cure resin cement with 10-MDP)
what do you use for a definitive cementation for an all ceramic bridge?
NEXUS (duel cure resin cement)
when should you use distal cantilevers and why?
avoid if possible
concern that occlusal forces on pontic will produce leverage forces on abutment tooth causing it to tilt
when may you consider a distal cantilever?
- may consider distal cantilever from premolar abutment if unopposed or opposed by a denture
what are all types of bridges?
- resin bonded/resin retained/adhesive
- conventional fixed-fixed
- conventional cantilever
- implant retained bridge
what bridge has best and worst survival rate over 5 and 10 years?
best 5 years - implant retained bridge
worst 5 years - resin-bonded
best 10 years - conventional fixed - fixed (metal ceramic)
worst 10 years - conventional cantilever bridge
what does direct bridgework mean?
done chairside
what happens when it is an indirect bridgwork?
lab work is done
what happens during a heavy prep?
usually cut into dentine and dentine doesn’t give a good bond as enamel
when would you use alternatives for pontic during a direct?
when patient loses own tooth
explain process of direct resin retained bridge?
- cut root off crown
- remove any pulpal tissue from crown and pulp chamber
- etch contact points as well as composite over hole going into pulp chamber
- etch on interproximal of adjacent teeth
- prime and bond in areas were etched and place tooth back in and composite areas
- not long term solution so plan a long term one
why is fixed-fixed resin bonded ridge rare?
because complication is one of wings debonded which leads to small space which leads to bacteria gets in
when would a fixed-fixed resin bonded bridge be used?
- lower anteriors or post ortho
why do you use cantilevers more anteriorly?
arch of dentition makes it so that occlusal forces on a fixed-fixed will lead to abutment pulling pontics in diff directions leading to debonding of 1 surface and then plaque gets trapped underneath a wing causing caries
where is the 180 degrees wrap around prep used?
on palatal or lingual surface
how deep are occlusal rests?
2mm
why do you want a fixed-fixed on posterior teeth
- more likely as you want to spread occlusal load over several teeth
what do you do during a temporary restoration for prep if they are sensitive?
use sensitive toothpaste or prescribe duraphat
what does sandblasted do?
creates small indentations on fitting surface
what do you do during cementation?
- etch abutment tooth
- apply A and B primer that mixed together apply microbrush about 30 sec. 5 layers on abutment tooth. air thin for sec or 2. it is self curing
- put resin cement on fitting surface
- seat it home while starting to set and clean up excess
when is there a higher risk of failure for bridges?
- when abutment tooth is smaller than pontic
what if there is high occlusal contacts on retaining wings?
going to get relative axial tooth movements without any issues of bridge coming off - not ideal situation
not ideal but when would a fixed-fixed on upper anteriors with both canines as abutments work?
- a class 2 occlusion or anterior open bite
- because it wont have much occlusal contact
what does overtaper result in?
reduced retention
what is degree of taper for fixed-fixed?
5-7 degrees
why is mesial cantilever preferred?
- reason is when patients occlude they are more likely to bite onto posterior teeth before anterior ones
what does a wash through pontic do?
give patient extra occlusal contact to bite on
more for a lower molar and is for function not appearance
when is ovate pontic used?
- for pts with good OH but want best aesthetic result.
- pushes down onto gingiva and gives look of pontic piercing out of gum
what is properties of zirconia and lithium disilicate?
ceramic is more likey to fracture than metal
- zirconia - stronger but poorer aesthetic
- lithium disilicate - weaker but better aesthetic
what is cerometric and when is it used?
- basically porcelain and composite
- not really used anymore
what would you put on prescription for conventional bridgework to the lab?
- name abutment teeth
- pontic you want
- shape of pontic
- materials want to use
etc
what is difference between adhesive and conventional by how they look?
adhesive has a metal wing because of minimal prep
conventional has another crown on top of abutments as it requires significant prep
