Treatment Planning and Biomechanics

Question 1

what is a fixed partial denture/ bridge

Answer 1

a dental prosthesis definitively attached to remaining teeth or to dental implants which replaces one or more missing teeth

Question 2

what is the abutment

Answer 2

natural tooth or implant serving as attachment for FPD

Question 3

what is the retainer

Answer 3

extra coronal restoration cemented to abutment

Question 4

what is the pontic

Answer 4

artificial tooth suspended from abutments

Question 5

what is the connector

Answer 5

rigid or non rigid connecting pontic and retainers

Question 6

what is the edentulous ridge

Answer 6

the site of the alveolar bone and its covering soft tissues that remains after tooth loss

Question 7

what is the state of dynamic equilibrium

Answer 7

equal pressures keeping teeth in their locations

Question 8

what are the possible consequences of unrestored tooth loss

Answer 8

• tooth movement
• no tooth movement

Question 9

what are the types of tooth movement seen in unrestored tooth loss

Answer 9

• over eruption
• tilting and drifting
• disruption of occlusion: pain and TMJ dysfunction

Question 10

what are the options for a partially edentulous patinet

Answer 10

• RPD
• tooth supported FPD- conventional, resin-bonded, or cantilever
• implant supported FPD
• do nothing

Question 11

what are the indications for RPD

Answer 11

• long edentulous spans
• no distal abutment
• multiple edentulous spaces
• abnormal abutments- tipped, divergent or few abutments
• periodontally weakened primary abutments
• severe loss of tissue/bone in residual ridge

Question 12

what is key for the success of a bridge

Answer 12

occlusion

Question 13

what are the indications for a FPD

Answer 13

• to replace function of missing teeth
• to stabilize occlusion and keep teeth from drifting and extruding
• to create esthetics and phonetics

Question 14

where should the abutments be placed so they are properly distributed

Answer 14

• abutment on both ends of edentulous spaces
• span length falls within structural limits
• straight alignment of restoration

Question 15

what are the requirements for abutment strength

Answer 15

• abutments need to be restorable
• periodontally sound and stable
• no questionable pathology
• occlusal harmony

Question 16

what are the contraindications for FPD

Answer 16

• excessive loss of alveolar bone
• abutments not restorable
• abutments are periodontally compromised

Question 17

why is FPD contraindicated with excessive loss of alveolar ridge

Answer 17

• difficulty cleaning
• difficulty making esthetic

Question 18

how can you correct excessive loss of alveolar ridge

Answer 18

bone graft or augmentation with perio surgery

Question 19

what would make abutments not restorable for a FPD

Answer 19

• short clinical crown
• heavily restored already

Question 20

what would qualify abutments as periodontically compromised

Answer 20

• loss of bone
• crown to root ratio
• span between abutments are too long

Question 21

what do you do with virgin or minimally restored abutments

Answer 21

purse implant options for the missing tooth

Question 22

what does the ideal FPD look like

Answer 22

• periodontally sound abutments
• tissue follows contour of pontic and connector
• span is within structural parameters

Question 23

what are the criteria we use for abutment evaluation

Answer 23

• restorative assessment
• endodontic assessment
• periodontal assessment
• abutment positional assessment
• radiographic assessment

Question 24

what is included in the restorative assessment

Answer 24

• coronal tooth structure
• previous restorative treatment

Question 25

what is included in the endo assessment

Answer 25

- pulp staus- vital or non vital - PARL - previous endo in -tact?

Question 26

what is included in the periodontal assessment

Answer 26

crown to root ratio, root configuration, periodontal surface area

Question 27

what is included in the abutment positional assessment

Answer 27

is the tooth tilted? inclined? - what is the tooth orthodontic position? - is the path of insertion achievable?

Question 28

how recent should PA radiographs be to be considered current enough to confirm the health of abutments

Answer 28

less than 6 months old

Question 29

what are the periodontal health qualifications for FPD

Answer 29

- need a zone of attached tissue - no mobility - patient home care adequate

Question 30

what is the optimum crown to root ratio

Answer 30

2:3

Question 31

what is the minimum crown to root ratio for fixed restoration

Answer 31

1:1

Question 32

the conical root shape _____ the area of support more than expected from the height of bone

Answer 32

decreases

Question 33

the center of rotation moves ____ and the lever arm ____, greatly magnifying the forces on supporting structures

Answer 33

apically; increases

Question 34

what can a bad crown to root ratio lead to

Answer 34

increased tooth mobility - further bone loss - failure of FPD

Question 35

what are the exceptions to crown to root ratio guidelines

Answer 35

-if opposing occlusal forces are diminished such as - artificial teeth - full denture or RPD - periodontally compromised opposing teeth

Question 36

muti rooted teeth are _____ than single rooted conical teeth

Answer 36

better

Question 37

widely separated roots are _____ abutments than fused roots

Answer 37

betterl

Question 38

long roots are ____ abutments than short roots

Answer 38

better

Question 39

what is ante's law

Answer 39

the root surface area embedded in bone of the abutment teeth should be equal or surpass that of the teeth being replaced with pontics

Question 40

how do you calculate ante's law

Answer 40

add the abutment numbers and subtract the pontic numbers

Question 41

any FPD replacing more than 2 posterior teeth has a ______ prognosis

Answer 41

guarded

Question 42

why can maxillary FPDs replacing more than 2 posterior teeth be acceptable

Answer 42

the maxillary arch has longer crowns and less tooth inclinations

Question 43

describe the path of insertion

Answer 43

axial walls of abutment teeth must be aligned without undercuts or interferences with path of insertion of the bridge

Question 44

why can tipped teeth be difficult to prepare effectively

Answer 44

- can expose mesial pulp horn - unfavorable occlusal forces if tilt is too significant - possible orthodontic uprighting prior to preparation

Question 45

what happens with alginate too dry or absorbed too much water

Answer 45

creates defects

Question 46

using casts you can evaluate:

Answer 46

- edentulous spaces and span length - curvature of the arch - M-D drifting, rotations, F-L displacement of the abutments - inclination - occlusion and inter occlusal space - path of insertion

Question 47

what needs to be evaluated on radiographs for abutment teeth

Answer 47

- caries - RCT present - bone levels - maxillary sinus

Question 48

what types of radiographs are mandatory for bridge work

Answer 48

full mouth series

Question 49

when is a marilyn bridge used

Answer 49

- conservative enamel prep only - replaces missing maxillary lateral incisors with slight to moderate tissue resorption in missing tooth area - used in younger patients - in areas of light occlusal stresses and good alignment of neighboring teeth

Question 50

when is a marilyn bridge not used

Answer 50

in deep vertical overlaps AKA deep bites

Question 51

how is the marilyn bridge bonded

Answer 51

resin bonded

Question 52

what is the characteristic appearance of the marilyn bridge

Answer 52

wings from canine to canine lingual surface

Question 53

what is a cantilever

Answer 53

a FPD that has abutments at one end with the pontic remaining unconnected on the other end

Question 54

what are the indications for an implant supported FPD

Answer 54

- implant abutments are soundly integrated - implant parallelism - availability of bone to support implant - patient demonstrates adequate home care

Question 55

what are full arch implant supported FPD's down sides

Answer 55

- $25,000 per arch - patient cant remove - hygiene is a huge challenge - need to be replaced every 10 years

Question 56

what are the limitations of implant placement

Answer 56

- amount of bone - location of bone - anatomy

Question 57

what is needed for the best prognosis of bone for implants

Answer 57

vertical loading of implants

Question 58

what anatomy needs to be evaluated for implants

Answer 58

- maxillary sinus - inferior alveolar nerve - anterior angulation of bone