Treatment Planning and Biomechanics Flashcards
what is a fixed partial denture/ bridge
a dental prosthesis definitively attached to remaining teeth or to dental implants which replaces one or more missing teeth
what is the abutment
natural tooth or implant serving as attachment for FPD
what is the retainer
extra coronal restoration cemented to abutment
what is the pontic
artificial tooth suspended from abutments
what is the connector
rigid or non rigid connecting pontic and retainers
what is the edentulous ridge
the site of the alveolar bone and its covering soft tissues that remains after tooth loss
what is the state of dynamic equilibrium
equal pressures keeping teeth in their locations
what are the possible consequences of unrestored tooth loss
- tooth movement
- no tooth movement
what are the types of tooth movement seen in unrestored tooth loss
- over eruption
- tilting and drifting
- disruption of occlusion: pain and TMJ dysfunction
what are the options for a partially edentulous patinet
- RPD
- tooth supported FPD- conventional, resin-bonded, or cantilever
- implant supported FPD
- do nothing
what are the indications for RPD
- 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
what is key for the success of a bridge
occlusion
what are the indications for a FPD
- to replace function of missing teeth
- to stabilize occlusion and keep teeth from drifting and extruding
- to create esthetics and phonetics
where should the abutments be placed so they are properly distributed
- abutment on both ends of edentulous spaces
- span length falls within structural limits
- straight alignment of restoration
what are the requirements for abutment strength
- abutments need to be restorable
- periodontally sound and stable
- no questionable pathology
- occlusal harmony
what are the contraindications for FPD
- excessive loss of alveolar bone
- abutments not restorable
- abutments are periodontally compromised
why is FPD contraindicated with excessive loss of alveolar ridge
- difficulty cleaning
- difficulty making esthetic
how can you correct excessive loss of alveolar ridge
bone graft or augmentation with perio surgery
what would make abutments not restorable for a FPD
- short clinical crown
- heavily restored already
what would qualify abutments as periodontically compromised
- loss of bone
- crown to root ratio
- span between abutments are too long
what do you do with virgin or minimally restored abutments
purse implant options for the missing tooth
what does the ideal FPD look like
- periodontally sound abutments
- tissue follows contour of pontic and connector
- span is within structural parameters
what are the criteria we use for abutment evaluation
- restorative assessment
- endodontic assessment
- periodontal assessment
- abutment positional assessment
- radiographic assessment
what is included in the restorative assessment
- coronal tooth structure
- previous restorative treatment
what is included in the endo assessment
- pulp staus- vital or non vital
- PARL
- previous endo in -tact?
what is included in the periodontal assessment
crown to root ratio, root configuration, periodontal surface area
what is included in the abutment positional assessment
is the tooth tilted? inclined?
- what is the tooth orthodontic position?
- is the path of insertion achievable?
how recent should PA radiographs be to be considered current enough to confirm the health of abutments
less than 6 months old
what are the periodontal health qualifications for FPD
- need a zone of attached tissue
- no mobility
- patient home care adequate
what is the optimum crown to root ratio
2:3
what is the minimum crown to root ratio for fixed restoration
1:1
the conical root shape _____ the area of support more than expected from the height of bone
decreases
the center of rotation moves ____ and the lever arm ____, greatly magnifying the forces on supporting structures
apically; increases
what can a bad crown to root ratio lead to
increased tooth mobility
- further bone loss
- failure of FPD
what are the exceptions to crown to root ratio guidelines
-if opposing occlusal forces are diminished such as
- artificial teeth - full denture or RPD
- periodontally compromised opposing teeth
muti rooted teeth are _____ than single rooted conical teeth
better
widely separated roots are _____ abutments than fused roots
betterl
long roots are ____ abutments than short roots
better
what is ante’s law
the root surface area embedded in bone of the abutment teeth should be equal or surpass that of the teeth being replaced with pontics
how do you calculate ante’s law
add the abutment numbers and subtract the pontic numbers
any FPD replacing more than 2 posterior teeth has a ______ prognosis
guarded
why can maxillary FPDs replacing more than 2 posterior teeth be acceptable
the maxillary arch has longer crowns and less tooth inclinations
describe the path of insertion
axial walls of abutment teeth must be aligned without undercuts or interferences with path of insertion of the bridge
why can tipped teeth be difficult to prepare effectively
- can expose mesial pulp horn
- unfavorable occlusal forces if tilt is too significant
- possible orthodontic uprighting prior to preparation
what happens with alginate too dry or absorbed too much water
creates defects
using casts you can evaluate:
- 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
what needs to be evaluated on radiographs for abutment teeth
- caries
- RCT present
- bone levels
- maxillary sinus
what types of radiographs are mandatory for bridge work
full mouth series
when is a marilyn bridge used
- 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
when is a marilyn bridge not used
in deep vertical overlaps AKA deep bites
how is the marilyn bridge bonded
resin bonded
what is the characteristic appearance of the marilyn bridge
wings from canine to canine lingual surface
what is a cantilever
a FPD that has abutments at one end with the pontic remaining unconnected on the other end
what are the indications for an implant supported FPD
- implant abutments are soundly integrated
- implant parallelism
- availability of bone to support implant
- patient demonstrates adequate home care
what are full arch implant supported FPD’s down sides
- $25,000 per arch
- patient cant remove
- hygiene is a huge challenge
- need to be replaced every 10 years
what are the limitations of implant placement
- amount of bone
- location of bone
- anatomy
what is needed for the best prognosis of bone for implants
vertical loading of implants
what anatomy needs to be evaluated for implants
- maxillary sinus
- inferior alveolar nerve
- anterior angulation of bone
