fixed dental prosthesis

Question 1

types of dental prostheses

Answer 1

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

Question 2

fixed dental prosthesis are done for:

Answer 2

1) tooth loss
2) perio
3) trauma
4) caries

Question 3

components of fixed prostheses

Answer 3

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

Question 3

framework

Answer 3

structural component without layered porcelain
- metal
- zirconia

Question 4

why do we wait for the gum to heal before starting bridge work

Answer 4

1) need the bone to be resorbed and for tissue site to be stable

Question 5

simple bridges

Answer 5

1) one or two missing teeth
2) attached to two natural teeth
3) full coverage

Question 6

cantilever

Answer 6

1) pontic hangs off ONE retainer
2) set up strange forces in mouth
- may still be suitable for certain cases

Question 7

maryland

Answer 7

1) wings are bonded to lingual of anterior teeth
2) conservative approach
3) huge comeback due to better bonding

Question 8

stress breakers

Answer 8

1) attachments on connectors that relieve undue pressure on abutment teeth

Question 9

dentures

Answer 9

1) full dentures
2) removeable partial dentures (RPDs)
3) stay plates
- may be interim prosthesis

Question 10

implant supported prostheses

Answer 10

1) individual crowns
2) bridges
3) implant supported dentures

Question 11

saddle (ridge lap)

Answer 11

1) cannot be maintained via flossing

Question 12

modified ridge lap

Answer 12

1) open on the lingual side
- can be used with floss
2) most popular for posterior

Question 13

conical

Answer 13

1) apex of pontic sits on tissue
- kissing the tissue
2) embrasures are large
- food gets trapped
3) can be flossed

Question 14

hygenic

Answer 14

1) the pontic is not touching the tissue
2) will collect everything you eat
- worst food trap
3) cleaned easily

Question 15

ovate

Answer 15

1) recent extraction
2) most aesthetic pontic design
- best emergence profile
3) can still be cleaned

Question 16

special case cantilever bridge

Answer 16

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

Question 17

special case pier abutment

Answer 17

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

Question 18

suitability of abutment teeth

Answer 18

1) periodontal support
2) root configuration
3) endodontic status
4) root orientation

Question 19

periodontal support

Answer 19

• length of roots
• bone loss
• crown-to-root ratio

Question 20

root configuration

Answer 20

• number of roots
• divergence of roots

Question 21

endodontic status

Answer 21

• vitality (pulp test)
• apical lesions
• adequacy of fill
• over-instrumentation (loss of radicular dentin)
• extent of preparation
• appropriateness of posts

Question 22

root orientation

Answer 22

• parallelism of abutments
• relation to occlusal plane

Question 23

ante’s law

Answer 23

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

Question 24

why do we care about ante’s law

Answer 24

1) prevent fracture from occlusion
2) torque on abutments
3) difficulties with retention and draw
4) de-cementation
5) inaccuracies in impressions

Question 25

how to solve this?

Answer 25

1) double-abut
2) splint the abutment to another tooth
—
not possible
1) consider removable or implant options

Question 26

draw

Answer 26

1) like drawing a sword; movement

Question 27

taper and path of draw

Answer 27

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

Question 28

spee and wilson

Answer 28

1) the curve of the jaw messes with the draw
2) they do not all have parallel long axis

Question 29

an extreme case

Answer 29

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)

Question 30

average curve of spee

Answer 30

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

Question 31

megatooth prep procedure

Answer 31

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)

Question 32

how to check for draw

Answer 32

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

Question 33

extraorally, check with

Answer 33

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

Question 34

reduction putties

Answer 34

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

Question 35

extract #30

Answer 35

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

Question 36

don’t

Answer 36

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