Fixed Exam 1 - Selection of Abutment Teeth Flashcards
What are the 7 critical factors when selecting abutment teeth?
Crown-root ratio
Root config
PDL
Biomechanics
Perio health
Endo
Pier abutments
As the level of bone moves apically, the crown/root ratio __________, which compromises the tooth prognosis
increases
What are the causes of increased crown/root ratio?
Perio
Supereruption
What do you use for the crown/root ratio: anatomical crown or clinical crown?
Clinical crown
Crown/root ratios above _____ are unacceptable (clinical crown > clinical root)
1.0
What is the most favorable crown/root ratio?
2/3
Roots with greater _________ widths are preferred to circular
labiolingual
T/F: Roots that are spread-out are better
True
T/F: Shorter roots are better than longer roots
FALSE, longer roots are better
Total root surface area of all supporting teeth must be equal to or exceed the total root surface area of teeth being replaced
Ante’s Law
(number of pontics)^3 = ?
FDPs deflection
Directly proportional; the bigger the span length in this direction, the bigger the deflection
Mesiodistal (span length)
Inversely proportional; the thicker the restoration in this direction, the smaller the deflection
Occlusogingival (span length)
Dislodging forces on a FDP tend to act in a __________ direction, as opposed to buccolingually with a single crown
mesiodistal
Bridge preps should be modified with retentive grooves on _________ and _________ to obtain better retention and resistance form
buccal; lingual
Where is there a high risk of margin leakage due to tensile forces created while the FDP is under load?
Secondary abutments
T/F: Secondary abutments should be avoided when possible
True
When pontics lie outside the interabutment axis line (fulcrum line), they act like a __________ ________, which produces a ____________ force under load
lever arm; torquing
Where are pontics lying outside the interabutment axis line (fulcrum line) most commonly seen?
Anterior
What is required in a case where pontics are lying outside the interabutment axis line (fulcrum line)?
Secondary abutment
The retainer’s width span should be ____________ than the pontic lever arm
equal or bigger
Order the following from smallest to greatest force:
Natural dentition
Removable dental prosthesis
Complete denture
Implant supported restoration
Complete denture
Removable dental prosthesis
Natural dentition
Implant supported restoration (greatest force)
What are 3 other things to consider when looking at occlusion?
Bruxism/clenching
Parafunctional habits (chewing ice, eating nuts)
Neighbor teeth
What is a prerequisite for all fixed restorations?
Healthy perio tissues
T/F: If the crown/root ratio is already questionable (1), perio health and OH must be excellent. If not, FDP will have a poor prognosis
True
When would elective endo treatment be indicated in order to fabricate an FDP?
(pulp will be exposed to obtain appropriate path of insertion/clearance)
Angled teeth
Supererupted teeth
What is preferred for most cases to position teeth in the correct orientation before fabricating an FDP?
Ortho
Natural tooth or implant abutment that is located between terminal abutments that serve to support a fixed or removable dental prosthesis
Intermediate abutment
When should a conventional (long span) FDP be avoided? What could happen?
When a pier abutment is present; creates stress on terminal and pier abutments
What are the following complications of?
Rocking of retainers
Bending of FDP
Tensile forces btwn retainers & abutments
Intrusion of pier abutments
Margin microleakage
Pier abutments
What is the ideal treatment option when you have to work around a pier abutment?
Implant
