Quiz 2 Review Flashcards
what are some of the indications for an FPD?
- medical contraindication to implants
- grossly inadequate alveolar bone for implant placement
- treatment following implant failure
- patient time constraints and/or circumstances that preclude implant placement
- patient that does not want an implant
of partial coverage and full coverage bridges, which is more retentive?
full coverage
what is an abutment tooth?
the tooth that supports the FPD
what is the retainer part of an FPD?
the crown
what is a pontic?
the missing tooth
what is the connector on an FPD?
the joint between the teeth
what is a splinted crown useful for?
teeth that are going to be abutments for an RPD, perio/mobility, or increased retention
what are the disadvantages of splinted crowns?
- flossing is compromised
- if one fails, they both fail
- retrievability is complicated
label this
T or F:
all of the same factors that influence resistance and retention for single units apply to fixed bridges
true
retainers with increased ___ height are more retentive than retainers with decreased ___ height
axial wall, axial wall
does increased abutment taper increase or decrease the resistance and retention of the retainers?
decreases
why is abutment taper of increased out of necessity? what can this increased axial wall taper create?
- to align abutments and allow a path of insertion
- it can create extra stresses on pulpal tissues
part of the pre-operative assessment for fixed bridges should always include the alignment of the proposed ___
abutment teeth
what are 5 fixed bridge designs?
- pier to pier (pier refers to the abutment)
- pier to pier to pier
- cantilever
- keyway feature
- combinations
why should you avoid the pier to pier to pier fixed bridge design?
the terminal abutments will often loosen and the middle abutment becomes a fulcrum
T or F:
a double abutment refers to two abutment teeth right next to each other, which is a better option than a pier to pier to pier design
true
how many pontics can be used in a cantilever bridge?
- one pontic only
- this is not an absolute, but will keep you out of trouble
with cantilever bridges, where should the pontic be? what is the exception?
- the pontic should be mesial to the retainer
- except maxillary central carrying a maxillary lateral
- this is not an absolute, but will keep you out of trouble
which two single abutments cannot be used with cantilever bridges?
- mandibular incisor or maxillary lateral incisor
- this is not an absolute, but will keep you out of trouble
___ rests should be used when possible with cantilever bridges
- cingulum/marginal ridge rests
- this is not an absolute, but will keep you out of trouble
based on clinical results of a 2-unit cantilevered resin-bonded fixed partial denture, they are found to be a durable prosthesis over the long term with high patient satisfaction. what is the consideration with the posterior prosthesis?
it has a higher failure rate, and improved design features should be considered (the janis bridge)
list 11 factors to consider with bridges
- parafunctional habits
- periodontal health
- plaque control/caries susceptibility
- occlusion
- root angulation
- root form
- root surface area
- retrievability
- crown/root ratio
- length of span
- endodontic health
what are 6 occlusion considerations for bridges?
- is the TMJ complex healthy?
- are the condyles seated?
- are occlusal forces controlled?
- does the bridge involve the patient’s anterior guidance?
- is an occlusal adjustment indicated?
- should splint therapy be considered?
what are parafunctional considerations for bridges?
- accelerated occlusal wear?
- tooth mobility?
- temporomandibular pain?
- tooth fracture?
- are the same factors that contributed to the tooth loss unresolved?
whata re root angulation considerations for bridges?
- are the roots in line with occlusal forces?
- if not, how much off angle is acceptable?
- is orthodontic uprighting necessary?
- us orthodontic uprighting possible?
if root angulation is off, what is it sometimes necessary to do in preparation for a bridge?
- recontour the proximal contacts of adjacent teeth
- prepare abutment teeth off-axis
if root angulation is off, pre-operative ___ therapy can significantly enhance long-term prognosis of prosthodontic therapy
orthodontic
what are root form considerations for bridges?
- conical and short vs irregular and long?
- are there thin areas, especially concavities, that are especially prone to fracture?
what is ante’s law? what year was it developed? what is the exception?
- the total periodontal membrane area of the abutment teeth must equal or exceed that of the teeth to be replaced
- in other words, the total root surface area of the teeth to be replaced should not be greater than the total root surface area of the abutment teeth
- 1926
- really long canines are the exception
ante’s law is useful for determining ___ of fixed dental prostheses
prognosis
with respect to percentage of root surface area per quadrant, the maxillary central and lateral incisors together make up about ___% of the total for the maxilla, and the mandibular central and lateral incisors together make up about ___% of the total for the mandible.
- maxilla: 19% (central = 10, lateral = 9)
- mandible: 17% (central = 8, lateral = 9)
which tooth overall has the greatest PERCENT root surface area?
mandibular first molar
which tooth overall has the greatest root surface area?
maxillary first molar
with respect to crown/root ratio, the ___ of roots accelerates the negative impact of crestal bone loss
conical shape
the deflection of a fixed dental prosthesis is proportional to the ___
- cube of the length of its span
- so, D = F x S3
- D = deflection
- F = force
- S = span
what is the deflection of a bridge with 1 pontic, 2 pontics, and 3 pontics?
- D = F x S3
- assume F = 1
- 1 pontic: D = 1 x 13 = 1
- 2 pontics: D = 1 x 23 = 8
- 3 pontics: D = 1 x 33 = 27
T or F:
a double abutment at the terminal end of a FPD is considered a pier abutment
- false, it is not considered a pier abutment
- for it to be considered a pier abutment, there must be a pontic separating the two retainers
a double abutment is an acceptable method of increasing ___ support for a FPD
periodontal
every tooth that is included in a fixed bridge increases the vulnerability of ___
- every other tooth that is part of the same bridge
- what affects one, now affects them all
T or F:
when designing FPDs, retrievability is not an important consideration
false, it’s definitely important
a ___ is an artifical tooth replacing a missing natural tooth that is designed to restore function and appearance
pontic
what are 5 pontic types?
- sanitary/hygienic
- saddle/ridge-lap
- conical/bullet
- modified ridge-lap
- ovate/socketed
what type of pontic is this?
sanitary/hygienic
what type of pontic is this?
saddle ridge-lap
what type of pontic is this?
conical
what type of pontic is this?
modified ridge-lap
what type of pontic is this?
ovate
what is the minimum clearance for a sanitary/hygienic pontic?
2mm
in the modified ridge lap, the area that contacts tissues resembles what letter?
T
put the following pontic designs in descending order of strength
strength is based on cross-sectional diameter of the metal substructure
which of the following is the correct design?
how can pontics be adjusted to create the illusion of being smaller or larger?
- line angles can be adjusted
- this can be applied to any prosthesis, retainer, crown, or pontic
positioning the ___ can help to create a width illusion
- buccal occluso-gingival height of contour
- this applies to any prosthesis, retainer, crown, or pontic
what are 4 types of connectors?
- cast metal connector
- soldered connector
- ceramic connector
- nonrigid connector (keyway or mortise and tenon)
put the following connectors in order of decreasing strength: soldered metal, all ceramic (zirconia, lithium disilicate, cast metal)
cast metal > soldered metal > all ceramic
T or F:
connectors with larger dimensions have less strength than smaller connectors
false
how do you calculate the area of a circular connector?
πr2
how do you calculate the area of a elliptical connector?
- abπ
- a = radius of long side
- b = radius of short side
between a connector with a longer BL width versus a longer occluso-gingival width, which will best resist occlusal loading?
the one with a longer occluso-gingival width
what are the minimum recommended cross-sectional dimensions for 3-unit posterior connectors for cast metal, solder, and ceramic (zirconia vs lithium disilicate)?
- cast metal = 6mm2
- solder = 9mm2
- zirconia = 9mm2
- lithium disilicate = 16mm2 (this is too big for more applications)
where is the connector position?
what are 3 nonrigid connector designs?
- keyway
- mortise and tenon
- male and female
what are 6 most common reasons for bridge failures?
- fractured porcelain
- recurrent caries
- loosened single retainer
- fracture abutment
- connector failure
- excessive gap formation between pontic(s) and the edentulous ridge, especially in the anterior region
what are 2 important things to advise your FPD patients?
- everything we do has a life expectancy
- even under the best of circumstances, there will be food traps with either a bridge or an implant
many studies demonstrate that shortened dental arches comprising the ___ and ___ regions can meet the requirements of a functional dentition. consequently, when priorities have to be set, restorative therapy should be aimed at preserving these parts of the dental arch
anterior and premolar
for chewing purposes, the minimum shortening of dental arches should include a pair of ___ in addition to intact ___
a pair of occluding molars in addition to intact premolar region
oral function is adequate in shortened dental arches comprising of intact ___ and ___ regions
anterior and premolar regions
T or F:
studies have shown that shortened dental arches often provoke signs and symptoms associated with temporomandibular disorders
- false
- no evidence was found that SDAs provoked signs and symptoms associated with temporomandibular disorders
- however, complete absence of posterior support unilaterally or bilaterally appeared to increase the risk for developing signs and symptoms associated temporomandibular disorders
extreme SDAs, comprising 0-2 pairs of occluding premolars, had significantly more ___, ___, and ___ compared to intermediate categories of SDAs
- interdental spacing
- occlusal contact
- vertical overlap
- *occlusal wear and tooth mobility were also highest in extreme SDAs
satisfactory chewing ability is perceived as long as the dental arch comprises an intact ___ region and ___ occluding pairs of teeth posteriorly
- anterior
- 3-5
SDAs comprising 3-4 occluding pairs of premolars posteriorly did not significantly differ from complete dental arches with regard to ___, ___, ___, and ___
- interdental spacing
- occlusal tooth wear
- vertical overbite
- tooth mobility
the risk to occlusal instability seemed to occur in extreme SDAs comprising ___ occluding pairs of teeth whereas no such evidence was found for intermediate categories of SDAs
0-2
as long as ___ support is present bilaterally, signs and symptoms of temporomandibular disorders are unlikely to manifest themselves. increased risk was only found when ___
- premolar
- increased risk was only found when all posterior support was unilaterally or bilaterally absent
how many occluding units denotes a severely compromised SDA? what about adequate SDA? functional SDA?
- 0-2 OU is severely compromised and likely to continue deteriorating
- 3-4 OU is often adequate
- 5+ OU, though not ideal, is often very functional
what are 6 contraindications to shortened dental arches?
- marked dento-alveolar malrelationship - severe angle class II or III relationship
- parafunction - intensive bruxism
- pre-existing TMD
- advanced pathological tooth wear
- advanced periodontal disease - marked reduction in alveolar bone support
- patient under age 40
the survival of 3-unit tooth supported fixed dental prostheses and implant supported single crowns over 15 years was not statistically different when replacing ___ teeth, but implant supported single crowns survived significantly better when replacing ___ teeth
posterior, anterior
T or F:
removable, fixed, fixed-removable, and implant-supported prostheses all produced significant improvement in oral health related quality of life
true
among patients treated with removable, fixed, fixed-removable, and implant-supported prostheses, the least amount of improvement was observed in patients with ___
removable dental prostheses
among patients treated with removable, fixed, fixed-removable, and implant-supported prostheses, oral health related quality of life was comparable between which two?
FPDs and implant-supported fixed prostheses
among patients treated with removable, fixed, fixed-removable, and implant-supported prostheses, the same treatment can have different impacts on the oral health related quality of life of partially edentulous individuals depending on their ___ and ___
age and kennedy classification
what are the ideal reduction measurements for an anterior bridge preparation?
- facial depth at margin = 1.2-1.7mm
- use two-plane facial reduction
- lingual depth at margin = 0.5-1.0mm
- incisal reduction = 2.0-2.5mm
- incisal edge should be perpendicular to the long axis of the tooth
- lingual concavity depth = 1.0-1.5mm
- softened line and point angles
how much clearance do you want between opposing teeth when prepping a tooth for a bridge?
1.0-1.5mm
T or F:
when taking a bite registration, you only want to inject the impression material over the prepared teeth
true
once trimmed, the bite registration should not contact what?
- soft tissue
- occluding surfaces of teeth not diretly involved with the preparations
when curing a temporary bridge, what order should you cure it?
- pontic area first, then move to retainer teeth
- after removing the temporary, cure the intaglio surface
T or F:
triad material bonds to composite resin foundation materials
true
proper embrasure form of temporary bridges enhances what 3 things?
esthetics, cleansability, and gingival health
custom tray material should extend ___mm onto soft tissue when possible
5-10mm
the custom tray handle should attach at ___ degrees at the incisal edge
45-60 degrees
when curing the custom tray in the triad machine, it should initially cure for ___ minutes, then the tray should be removed from the model/wax, then cured again for ___ minutes per side
- 1 minute
- 4 minutes per side
what are the 4 advantages of custom trays for fixed prosthodontics?
- comfortable for patient
- stiff and unbendable
- less impression material
- consistent accuracy
what are the indications for a custom tray?
- 3+ units
- bridges
- removable partial dentures
- implants
what are the advantages of rigid stock trays?
- less time intensive
- variety of sizes
- customizable
what are the disadvantages of rigid stock trays?
- requires more impression material
- requires more time chairside if not made, pre-clinically, from patient’s cast
