Bridges Flashcards
Benefits of Resin Bonded Bridges (4)
Minimally invasive
Good survival rate
Cheap and fast
Ideal for hypodontia cases
What must you consider when designing adhesive bridges (8)
Perio support
Occlusal loading (which way force will go)
Conservative design
Cleansability
Aesthetics
Rigidity
Abutment (quant and qual)
Choice of adhesive luting (cement)
Why are single unit, cantilevers the best (3)
Pontic moves with abutment
Reduced shear forces on pontic
Lower risk of debond and caries
min thickness of retainer in adhesive bridges
0.7mm
how much prep for adhesive bridges?
kept to an absolute minimum
- Anterior teeth may not even be prepped at all
pros (3) and cons (2) of no prep adhesive bridges
Pros:
- Conservative, leaves enamel for bonding
- no sensitivity
- if not in occ, no need for cingulum rest
Cons:
- a lot of load on cement if teeth are in occlusion
- may be difficult to locate the wing during cementation (is it in the right place?)
2 types of preparation for adhesive bridges + reasoning
- axial tooth prep
- increases SA for bonding, resistance and retention form - Grooves
- resists lateral displacment
- increase rigidity
- increases resistance to debonding forces
Should you place a cingulum rest when doing prep for an adhesive bridge? why or why not?
Only if tooth is already restored and you are drilling into comp- helps resist axial forces. helps locating position as well.
IF tooth is unrestored, better to preserve enamel
What is the point of occlusal rest seats in adhesive bridges
Transmits occlusal forces along long axis of tooth
- should be kept minimal and within enamel
- Can also help locate the wing
Canines vs centrals as abutments for adhesive bridges
Canine:
- Bulbosity may cause connector to be too thin/fragile
- Impede aesthetics
- Use guide plane to overcome this
Centrals
- Metal can shine through due to translucent enamel
- Use opaque cement to overcome this
What teeth make for poor abutments (5)
- Laterals
- Tilted incisors (unfavourable pulp chambers)
- Root-filled
- Heavily restored
- Perio compromised
Mechanism of failure with fixed-fixed adhesive bridges
- Stress due to differential tooth movements between the abutments during tooth contact
- These forces tend to push one of the abutments away from the pontic
- Increased tensile stress on cement
- Debonding of abutment and caries under the retainer
same concept applies to double abutments (34+35 to replace 33)
pros and cons of prepped adhesive bridges
Pros:
- Conservative prep compared to conventional bridge
- fixed resto w/o compromising abutment
- Less endo complications resulting from extensive prep
- Faster and cheaper
Cons:
- technique sensitive
- aesthetic issues due to metal wing
- debonding issues
- lack of studies
synonym for adhesive bridge
RBB
Main challenge of anterior RBB and how to avoid (2)
Metal connector shine through
- Most common reason for patient dissatisfaction with RBB
Avoid by:
- Using opaque cement
- Design retainer to avoid extension of metal within 2mm of incisal edge
What is a locating tag used for in adhesive bridges / RBB
- helps you position the retainer in the correct orientation
- resists displacment during cementation
- if you didnt prep, can be difficult to position the pros exactly right
- Locating tag hangs over incisal edge
what to do if grey shines through the abutment from RBB and opaquer doesnt help? (2)
Consider changing the abutment tooth (ex. canine rather than central)
composite veneer
Why can fixed-fixed RBBs work anteriorly when using canines for abutments?
- Less occlusal loading than posterior
- Canines are good abutments bc:
- High SA
- Crown to root ratio
- Similar mvmt characteristics of abutment teeth
- Greying can be masked
Rules for occlusion in RBB
- Must do pre-op assessment of ICP, dynamic excursions to ensure room
- Should be in LIGHT contact, otherwise opposing tooth will overerupt
- pontic should NOT be involved in guidance, where possible
- ICP contact should be kept away from margin of retainer
- If space is limited, metal framework can be cemented high
pros (4) and cons (5) of fixed fixed bridges
pros
- predictable, aesthetic
- good for cases where implant not poss
- even force distribution
- can be used ant/post, long spans, perio spinting
cons
- invasive
- requires meticulous planning of occlusion
- pulpal death in abutments, will need to be remade after RCT
- $$$
- requires excellent OH
Advantages of canitlever bridges (5)
- Good aesthetics
- more conservative, less complications
- less chance of caries development
- non-catastrophic failure
- good option for single tooth replacement
Disadvantages of cantilever bridges (3)
- Risk of debonding, esp on RCT teeth
- Metal shine through
- Not ideal for load bearing cases
Advantages of fixed-movable bridges (4)
- since bridge can flex, less load on the retainer
- Allows for partial coverage- less prep
- Compensates for abutment misalignment
- Allows for individual mvmt of sections
Disadvantages of fixed-movable bridges (5)
- Destructive- think of dovetail prep on abutment
- Metal of joint may show
- Wear and mechanical failure of joint can happen
- Try in and cementation difficult
- Difficult for technician to make
3 types of stress that occur in a fixed bridge
tensile
compressive
shear stress
what type of stress is dental porcelain susceptible to?
Shearing
- when the resto is twisted
- thats why you see failure of PFM in the proximals, rather than occlusal
ideal measurement (thickness) of the metal connector in a bridge
at least 2.5mm occluso-gingivally and bucco-lingually
*will need to write this measurement of your desired thickness on lab forms for pfm
PFM vs Layered zirconia
(6)
PFM
- Stronger
- Better for posteriors
- Good for bruxists
- Can incorporate movable joint
- Potentially less invasive (metal backing w/o porcelain)
- Good long-term evidence
Layered zirconia
- Problems with chipping/breaking
- Aesthetic, better for anteriors
- Not ideal for bruxirs
- Cannot incorporate joints
- Lacks long-term evidence
Are pier abutments good?
No
Abutments will move differently -> leakage
- Do two single units instead
- Only time pier is good is in perio compromised teeth with some degree of mobility (splinting), but if abutments are healthy: “No no”
Solutions to malpositioned abutments (mesially drifted) (4)
- Recontour
- Telescopic crowns
- 3/4 crown prep w/ fixed/movable design (most conservative)
- ortho
3 considerations when choosing a pontic
- Cleansibility
- Abutment height
- Aesthetics
ID + pros (2) and cons (5)
Saddle Ridgelap
- Very aesthetic
- good pt adaptability bc it feels like real tooth
Cons:
- difficult to remove excess from under pontic
- poor cleaning ->
- food trap ->
- inflammation of soft tissues ->
- gingival recession
Pontic design consideration in relation to soft tissues
Pressure-free / passive contact btw pontic and soft tissues
Passive contact only on the attached gingiva, if contact on free gingiva, will ulcerate
ID + pros (4) and cons (2)
Modified ridge lap
Pros:
- good aesthetics
- easy to remove xs cement
- easier to clean
- can replace any tooth
Cons:
- requires pt adaptation (doesnt feel like real tooth)
- May cause air/saliva percolating through embrasures, esp in anterior during speaking
ID + pros (2) /cons (3)
Sanitary / Hygienic pontic
Pros:
1. Ideal cleansibility
2. Easy to remove excess cement from pontic
Cons:
1. Requires pt adaptation (doesnt feel like real tooth)
2. lacks aesthetics (posterior only)
3. pts need to accustom to design during provisionalisation before it can be made definitively
ID + pros (3) / cons (2)
Ovate pontic
Pros:
- most aesthetic
- ideal for anteriors, esp high lip lines
- OH can be maintained
Cons:
- requires more effort to mould soft tissue (ex. surgery to remove bone or soft tissues)
- requires multiple appts
What pontic to use for mx anterior + alt
Ovate
alt- mod ridge lap
What pontic to use for mx posterior
mod ridge lap
What pontic to use for md anterior + alt
ovate
alt- mod ridge lap
What pontic to use for md posterior + alt
Sanitary
alt- mod ridge lap
Most common fixed bridge complications in descending order
(8)
- Caries
- Need for RCT
- Lost retention
- Aesthetics
- Perio
- Tooth fracture
- Pros failure
- Porcelain fracture
