fixed dental prosthesis Flashcards
types of dental prostheses
1) replacement for a missing tooth
- individual crowns are NOT
2) fixed dental prosthesis (FDP)
- non removeable tooth replacement attached to natural teeth
- aka bridge/fixed partial denture
fixed dental prosthesis are done for:
1) tooth loss
2) perio
3) trauma
4) caries
components of fixed prostheses
1) abutment tooth
- prepared natural tooth to which the FDP is attached
2) retainer
- restoration over the prepped abutments
3) pontic
- tooth analogue attached to retainers
4) connector
- rigid attachment of pontic to retainers
framework
structural component without layered porcelain
- metal
- zirconia
why do we wait for the gum to heal before starting bridge work
1) need the bone to be resorbed and for tissue site to be stable
simple bridges
1) one or two missing teeth
2) attached to two natural teeth
3) full coverage
cantilever
1) pontic hangs off ONE retainer
2) set up strange forces in mouth
- may still be suitable for certain cases
maryland
1) wings are bonded to lingual of anterior teeth
2) conservative approach
3) huge comeback due to better bonding
stress breakers
1) attachments on connectors that relieve undue pressure on abutment teeth
dentures
1) full dentures
2) removeable partial dentures (RPDs)
3) stay plates
- may be interim prosthesis
implant supported prostheses
1) individual crowns
2) bridges
3) implant supported dentures
saddle (ridge lap)
1) cannot be maintained via flossing
modified ridge lap
1) open on the lingual side
- can be used with floss
2) most popular for posterior
conical
1) apex of pontic sits on tissue
- kissing the tissue
2) embrasures are large
- food gets trapped
3) can be flossed
hygenic
1) the pontic is not touching the tissue
2) will collect everything you eat
- worst food trap
3) cleaned easily
ovate
1) recent extraction
2) most aesthetic pontic design
- best emergence profile
3) can still be cleaned
special case cantilever bridge
1) FDP with abutments on only one end
2) posterior
- poor prognosis
3) anterior
- especially maxillary lateral incisor pontic, canine abutment
- solid abutment, delicate pontic
- rotation prevented by tongue and lips
- good prognosis
special case pier abutment
1) abutment tooth with both adjacent teeth meeting
2) single piece FDP
- no violation of ante’s law
- pier becomes fulcrum
- downward forces in posterior create unseating forces in anterior
- frequent de-cementation
3) two piece FDP
- anterior segment cemented first
- posterior segment cemented to abutment, resting in distal of pier
- pier no long fulcrum
- metal frameworks only
- stress breaker, non-ridgid connector
suitability of abutment teeth
1) periodontal support
2) root configuration
3) endodontic status
4) root orientation
periodontal support
- length of roots
- bone loss
- crown-to-root ratio
root configuration
- number of roots
- divergence of roots
endodontic status
- vitality (pulp test)
- apical lesions
- adequacy of fill
- over-instrumentation (loss of radicular dentin)
- extent of preparation
- appropriateness of posts
root orientation
- parallelism of abutments
- relation to occlusal plane
ante’s law
1) peri-cemental surface area of the abutment teeth to be used for a fixed dental prosthesis must be equal to or exceed the peri-cemental surface of the teeth being replaced
2) aka root S.A. of #18 and #20 will be LARGER than #19 being replaced
why do we care about ante’s law
1) prevent fracture from occlusion
2) torque on abutments
3) difficulties with retention and draw
4) de-cementation
5) inaccuracies in impressions
how to solve this?
1) double-abut
2) splint the abutment to another tooth
—
not possible
1) consider removable or implant options
draw
1) like drawing a sword; movement
taper and path of draw
1) teeth with parallel long axis (of crown)
2) path of draw is parallel to long axis
3) outer walls will converge
4) inner walls will diverge
5) no undercuts
-
these preps DRAW with each other
spee and wilson
1) the curve of the jaw messes with the draw
2) they do not all have parallel long axis
an extreme case
1) teeth with very different long axis
- inner walls do not diverge or outer do not converge anymore
2) preps do NOT draw
–
1) you must find the average long axis
- path of draw
2) do preps along this axis
3) equal compromise for the teeth
do not do it if you might hit the pulp horn!!!
also you may not be able to seat it due to being undercut to the adjacent tooth (gets caught)
average curve of spee
1) 10 degree convergence
2) if you prep each tooth on its own…
- 10 degree taper on each wall
- 20 degree convergence of outer
- 0 degree divergence on inner
megatooth prep procedure
1) imagine the tooth extending over the three tooth’s length
2) prep outer walls first along path of draw
3) prep inner walls
4) prep buccals and both linguals
5) save occlusal reduction and bevels for last (to evaluate draw)
6) DO NOT PREP ONE TOOTH AT A TIME!!!
7) when establishing path of draw, follow long axis of the much smaller tooth a little bit more (because the tooth is less strong)
how to check for draw
1) close one eye and look from occlusal and do NOT change the angle when moving from tooth to tooth
2) use an explorer to check undercuts
3) move mirror to next tooth with no angle change
extraorally, check with
1) alginate and pour it up
2) you can pour up in blue stone (23-24 cc instead of 26)
- make it thick so it doesn’t break during pulling
3) mark axial walls of model with pencil
- not the margin, but get it close
4) takes about ~15 minutes
- do this BEFORE occlusal reduction so you can look at it
reduction putties
1) we are using clearance
- difficult to measure on 2nd molar
2) reduction putties will be guide for angulation and axial reduction
3) leave #30 in place, and make 2 putties for 29 and 30
- cut in middle, and keep the mesial halves of the putties
extract #30
1) put a small amount of paper just to cover the screw hole
2) take putty and shove it in the hole, smooth it out
- slightly convex
don’t
1) don’t leave #30 socket open
- cannot see draw well
2) don’t just prep tooth separately
- it will make it over-tapered
3) don’t wait until end to check draw with alginate
