L1- Treatment Planning and Biomechanics of FPD Flashcards
FPD may also be referred to as:
a bridge
A dental prosthesis definitively attached to remaining teeth or to dental implants which replaces one or more missing teeth:
FPD (bridge)
Label the following image:
A- retainer
B- pontic
C- connector
D- retainer
E- abutment tooth (prepped)
F- connector
G- abutment tooth (prepped)
H- abutment
I- abutment
J- edentulous ridge
Natural tooth or implant service as attachment for FPD:
Abutment
Extra-coronal restoration cemented to abutment:
retainer
Artificial tooth suspended from abutments:
pontic
Rigid (or non-rigid) connecting pontic and retainers
connector
The site of the alveolar bone and its covering soft tissues that remains after tooth loss:
edentulous ridge
What is the goal for every orthodontist?
intact dentition and a state of dynamic equilibrium
With an intact dentition and state of dynamic equilibrium, there are ___ keeping the teeth in their locations
equal pressures
In intact dentition and state of dynamic equilibrium, the teeth stay in position based on:
hitting opposing teeth
In this image we see loss of tooth #19. What are the results of this?
14 extrusion
#20 drifting distally
Space created between #20 & #21
#18 mesial tilt
14 extrusion
In this image we see loss of tooth #19. Resulting in:
#20 drifting distally
Space created between #20 & #21
#18 mesial tilt
These consequences are due to:
improper occlusal pressure and lack of inter-occlusal space
What type of interferences may result from this image?
excursive movement interferences and possible loss of full range of movement
Consequences of unrestored tooth loss include:
- tooth movement
- no tooth movement
The tooth movement that results from unrestored tooth loss may include:
- over-eruption
- tilting & drifting
- disruption of occlusion
- pain & TMJ dysfunction
T/F: For some reason, some teeth never move after loss of proximal or opposing contacts
True- freaks of nature
What should be done prior to bridge placement in regards to occlusion?
re-establishing harmonious occlusion
Give an example of re-establishing harmonious occlusion prior to bridge placement:
Placing a crown on a super-erupted tooth
____ are produces when an FPD is made to the over-erupted dentition
occlusal interferences
T/F: There will not be consequences when an FPD is made to the over-erupted dentition
false- occlusal interferences
When an opposing tooth is restored to a corrected occlusal plane, this prevents:
interferences
Restoring an opposing tooth to a corrected occlusal plane to prevent interferences may require: (7)
- odontoplasty
- restoration
- crown
- RCT
- crown lengthening
- intrusion
- extraction
When the teeth have been missing for a long time, extreme ____ of the ____ can occur which requires more extreme treatment planning and for the general dentist, likely a referral to a prosthodontist for treatment.
closure; inter-occlusal distance
What can be seen in this image?
extreme closure of inter-occlusal distance
What are some prosthetic treatment options for a partially edentulous patient?
- RPD
- Tooth-supported FPD
- Implant-supported FPD
- Nothing
A tooth supported FPD is a treatment option for partially edentulous patients. What are some design types?
- conventional
- resin-bonded
- cantilever
T/F: It is never an option to do nothing. This is considered negligence
False- ALWAYS an option to do nothing
List indications for a RPD:
- long edentulous spans
- no distal abutment
- multiple edentulous spaces
- abnormal abutments
- periodontically weakened primary abutments
- severe loss of tissue/bone in residual ridge
Abnormal abutments is an indication that an RPD is a better option than an FPD. Describe some abnormal abutments:
- tipped
- divergent
- few
Why would an RPD be indicated in this case?
no distal abutments
What information do you need to know to determine the prognosis of a fixed bridge for treatment planning?
- x-rays
- perio charting
- decay prevention
- home care
- reasons for previous tooth loss
- clencher/grinder?
- finances
- condition of existing crowns
Indications for an FPD:
- to replace FUNCTION of missing teeth
- to STABILIZE OCCLUSION and keep the teeth from drifting and extruding
- to create ESTHETICS & PHONETICS
In order to do an FPD, we need properly distributed:
abutments
List the requirements satisfying “properly distributed abutments” for a FPD:
- abutments on both ends of edentulous space
- span length falls within structural limits
- straight alignment of restoration (slight variations)
Describe what contributes to abutment strength:
- abutments need to be restorable
- periodontally sound & stable
- no questionable pathology (PARL, non-vital)
- occlusal harmony
Contraindications for an FPD include:
- excessive loss of alveolar ridge
- abutments not restorable
- abutments are periodontally compromised
Excessive loss of the alveolar ridge is a contraindication for an FPD. This is because-
- difficulty cleaning
- difficultly in esthetics
T/F: it is possible to correct excessive loss of alveolar ridge to some degree with bone graft/augmentation with periodontal surgery
True
In what situations would abutments for a FPD be “non-restorable” and therefore a contraindication if:
- short clinical crown
- heavily restored already
Abutments for an FPD are considered “periodontally compromised” and therefore a contraindication if:
- loss of bone
- crown to root ratio (bad)
- long span between abutments
With virgin or minimally restored abutments, we prefer to pursue:
implant options to preserve these potential abutment teeth
List some characteristics of an ideal FPD:
- periodontally sound abutments
- tissue follows contour of Pontic and connector
- span is within structural parameters
What are the criteria categories we use for abutment evaluation? (can you vs. should you)
- Restorative assessment
- Endodontic assessment
- Periodontal assessment
- Abutment positional assessment
- Radiographic assessment
Describe what is considered in regards to the RESTORATIVE ASSESSMENT for abutment evaluation:
- coronal tooth structure
- previous restorative treatment
Describe what is considered in regards to the ENDODONTIC ASSESSMENT for abutment evaluation:
- pulp status
- pathology
Describe what is considered in regards to the PERIODONTAL ASSESSMENT for abutment evaluation:
- crown to root ratio
- root configuration
- periodontal surface area
Describe what is considered in regards to the ABUTMENT POSITIONAL ASSESSMENT for abutment evaluation:
- Tilted?
- Inclined?
- Orthodontic position
- Path of insertion evaluation
Describe what is considered in regards to the RADIOGRAPHIC ASSESSMENT for abutment evaluation:
anomalies
How do we evaluate the abutment?
- clinical exam
- radiographic exam
- diagnostic casts
For the radiographic examination of an abutment, its recommended to do ____ for a patient that is considered complex
full mouth series
List some questions to be considered when evaluating the abutments:
- Adequate retention and resistance form possible?
- Adequate wall length?
- Is the tooth restorable as is or is decay present?
- If decay is present, can restorability be gained with foundation or modification of the prep?
- What is the apical extent of caries or restoration?
Tooth is asymptomatic with sound tooth structure remaining - When evaluating this tooth for abutment consideration, we would classify this as:
vital tooth (good candidate)
In regards to pulpal health, what would deem a tooth to be questionable as an abutment?
deep excavation, near pulp exposure, pinpoint exposure, inadequate RCT, or post
In order to confirm the health of abutments, we need current PA radiographs of less than:
6 months old (he prefers within weeks)
T/F: IF we are planning on a long-lasting FPD, then any questions about the foundation/abutment health needs to be addressed prior to making a definitive FPD
True
_____ health is a prerequisite for any fixed prosthodontics restoration
Periodontal
Describe “periodontal health prerequisites” in regard to abutment evaluation:
- need a zone of attached tissue
- no mobility
- adequate patient home care
In addition to the following periodontal health prerequisites, need a zone of attached tissue, no mobility, adequate patient home care…
What else is beneficial to evaluate for abutment evaluation?
- crown-to-root ratio
- root shape & configuration
- PDL area
Placing a finger on one side of the tooth and tapping firmly on the other side of the tooth with the mirror:
What test is this? What does it tell you?
Fremitous test; tells you if the tooth is completely solid in the socket
A solid sounding fremitous test =
tooth completely solid in socket
The ratio of the portion of the tooth occlusal to the alveolar crest versus the portion of the tooth embedded in the root:
crown to root ratio
What is an optimum crown to root ratio for an abutment tooth?
C:R 2:3
What is the minimum crown to root ration for an abutment tooth?
C:R 1:1 (for fixed restorations)
Horizontal bone loss dramatically reduces:
supported root surface area
____ dramatically reduces supported root surface area
horizontal bone loss
The ____ diminishes the actual area of support more than expected from the height of the bone
conical root shape
According to this image, the center of rotation (____) moves ____ and the lever arm (____) _____, greatly magnifying the forces on the supporting structures
R; apically
L; increases
The center of rotation (R) moves apically and the lever arm (L) increases, greatly magnifying the forces on the supporting structures.
This can increase _____, further ____, and ultimately ____
tooth mobility; bone loss; failure of FPD
What are the exceptions to the crown to root ratio guidelines?
If opposing occlusal forces are diminished such as:
- artificial teeth (full denture, RPD)
- periodontally compromised opposing teeth
What is a better abutment tooth? A multi rooted tooth or a single rooted conical tooth?
Multi-rooted tooth
What is a better abutment tooth? A multi rooted tooth with separated roots or a multi rooted tooth with fused roots?
Multi-rooted with separated roots
What is a better abutment tooth? A tooth with long roots or a tooth with short roots?
Long roots
What is a better abutment tooth? Single rooted tooth with a perfect taper or a single rooted tooth with irregular configurations/ curvatures?
single rooted tooth with irregular configurations/ curvatures
For an abutment tooth, a tooth that is broader ___ or ___ is preferred over a ___ tooth
FL or MD; round
The root surface area (embedded in bone) of the abutment teeth should be equal or surpass that of the teeth being replaced with pontics
Ante’s Law
When using Ante’s Law, a ____ number is considered favorable
positive
Use Ante’s Law to determine if the following FPD is favorable:
extracted: 207 + 431 = 638
adjacent teeth: (180+ 426 = 606)
(606 - 638) = negative number = unfavorable
T/F: Even if ante’s law results in a negative number (unfavorable), you may still be able to accomplish an FPD with very optimal occlusion:
true
Ante’s Law describes:
root surface
A general principle, is that any FPD replacing ____ has a guarded prognosis
more than 2 posterior teeth
Even though the general principle is that any FPD replacing more than 2 posterior teeth has a guarded prognosis, the ___ arch has longer crowns and less tooth inclinations and can therefore occasionally be acceptable
maxillary arch
What is NOT considered in Ante’s Law and therefore suggests there are shortcomings with Ante’s Law?
Occlusal scheme
Failures in FPDs are more due to biomechanical factors like _______, than due to overstressing of periodontal ligaments
(shortcomings of ante’s law)
- caries
- gingival inflammation
- poor framework design
- poor occlusion
- material failure
Failures in FPDs are more due to _____ than _____
biometrical factors; over stressing of PDL
T/F: Studies have revealed successful FPDs supported by periodontally weakened teeth
True
Conclusion:” _____ is the key to success. Event the worst cases with doubtful prognosis had good success rates when ___ was right.”
Occlusion; Occlusion
In regards to path of insertion of the bridge, ____ walls of abutment teeth must be aligned without undercuts or interferences.
Axial walls
Why have a tipped tooth be very difficult to prepare effectively in regards to path of insertion?
- exposure of mesial pulp horn
- unfavorable occlusal forces if tilt is significant
- possible orthodontic uprighting prior to prep
Using diagnostic casts, you can evaluates:
- Edentulous spaces & span length
- Curvature of the arch
- MD drifting & rotation
- FL displacement of abutments
- Inclination
- Occlusion & interocclusal space
- Path of insertion
When teeth are not perfectly aligned (which is very common), a ___ can be used to identify the path of insertion and to help you create the appropriate planes in tooth preparation to create a path of insertion
Surveyor
What anatomical feature should be evaluated on the radiograph?
Maxillary sinus (is there a lack of bone support due to sinus pneumatization)
T/F: Full mouth serious of radiographs within 12 months is nearly mandatory for any bridge work
False- FMX within 6 months!
For a partially edentulous patient, addition options for FPD include:
- Resin-bonded fixed partial prosthesis
- Cantilever fixed partial prosthesis
- Implant supported FPD
A resin-bonded fixed partial prosthesis may also be known as:
Marilyn bridge
A Marilyn bridge (resin-bonded FPP) has what type of prep?
conservative enamel only prep
A Marilyn bridge (resin-bonded FPP), is used for ____ with ___ .
single missing tooth with slight to moderate tissue resorption in missing tooth area
What are the requirements for the neighboring teeth with a A Marilyn bridge (resin-bonded FPP)?
only areas of light occlusal stress and good alignment with neighboring teeth
A Marilyn bridge (resin-bonded FPP), is not indicated for:
deep vertical overlaps (deep bites)
An excellent option in younger patients where age contraindicates implant or bridge?
A Marilyn bridge (resin-bonded FPP)
Most often used to replace missing maxillary lateral incisors:
A Marilyn bridge (resin-bonded FPP)
What would be an ideal option for a young patient missing their maxillary lateral incisors?
A Marilyn bridge (resin-bonded FPP)
A fixed partial denture that has an abutment(s) at one end with the Pontic remaining unconnected on the other end:
Cantilever fixed partial prosthesis
What type of prosthesis is seen in the following image?
Cantilever fixed partial prosthesis
What are indications for an implant supported FPD in a partially edentulous patient?
- implant abutments are soundly integrated
- implant parallelism
- availability of bone to support implant
- patient demonstrates adequate home care
Why are implant supported FPDs controversial?
- patient cannot remove
- Expensive
- hygiene is a challenge
- needs replacement every 10 years
What anatomy needs to be considered when placing implants?
- maxillary sinus
- IAN
- anterior angulation of bone
