Fixed Exam 1 - Selection of Abutment Teeth

Question 1

What are the 7 critical factors when selecting abutment teeth?

Answer 1

Crown-root ratio
Root config
PDL
Biomechanics
Perio health
Endo
Pier abutments

Question 2

As the level of bone moves apically, the crown/root ratio __________, which compromises the tooth prognosis

Answer 2

increases

Question 3

What are the causes of increased crown/root ratio?

Answer 3

Perio
Supereruption

Question 4

What do you use for the crown/root ratio: anatomical crown or clinical crown?

Answer 4

Clinical crown

Question 5

Crown/root ratios above _____ are unacceptable (clinical crown > clinical root)

Answer 5

1.0

Question 6

What is the most favorable crown/root ratio?

Answer 6

2/3

Question 7

Roots with greater _________ widths are preferred to circular

Answer 7

labiolingual

Question 8

T/F: Roots that are spread-out are better

Answer 8

True

Question 9

T/F: Shorter roots are better than longer roots

Answer 9

FALSE, longer roots are better

Question 10

Total root surface area of all supporting teeth must be equal to or exceed the total root surface area of teeth being replaced

Answer 10

Ante’s Law

Question 11

(number of pontics)^3 = ?

Answer 11

FDPs deflection

Question 12

Directly proportional; the bigger the span length in this direction, the bigger the deflection

Answer 12

Mesiodistal (span length)

Question 13

Inversely proportional; the thicker the restoration in this direction, the smaller the deflection

Answer 13

Occlusogingival (span length)

Question 14

Dislodging forces on a FDP tend to act in a __________ direction, as opposed to buccolingually with a single crown

Answer 14

mesiodistal

Question 15

Bridge preps should be modified with retentive grooves on _________ and _________ to obtain better retention and resistance form

Answer 15

buccal; lingual

Question 16

Where is there a high risk of margin leakage due to tensile forces created while the FDP is under load?

Answer 16

Secondary abutments

Question 17

T/F: Secondary abutments should be avoided when possible

Answer 17

True

Question 18

When pontics lie outside the interabutment axis line (fulcrum line), they act like a __________ ________, which produces a ____________ force under load

Answer 18

lever arm; torquing

Question 19

Where are pontics lying outside the interabutment axis line (fulcrum line) most commonly seen?

Answer 19

Anterior

Question 20

What is required in a case where pontics are lying outside the interabutment axis line (fulcrum line)?

Answer 20

Secondary abutment

Question 21

The retainer’s width span should be ____________ than the pontic lever arm

Answer 21

equal or bigger

Question 22

Order the following from smallest to greatest force:

Natural dentition
Removable dental prosthesis
Complete denture
Implant supported restoration

Answer 22

Complete denture
Removable dental prosthesis
Natural dentition
Implant supported restoration (greatest force)

Question 23

What are 3 other things to consider when looking at occlusion?

Answer 23

Bruxism/clenching
Parafunctional habits (chewing ice, eating nuts)
Neighbor teeth

Question 24

What is a prerequisite for all fixed restorations?

Answer 24

Healthy perio tissues

Question 25

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

Answer 25

True

Question 26

When would elective endo treatment be indicated in order to fabricate an FDP?

(pulp will be exposed to obtain appropriate path of insertion/clearance)

Answer 26

Angled teeth
Supererupted teeth

Question 27

What is preferred for most cases to position teeth in the correct orientation before fabricating an FDP?

Answer 27

Ortho

Question 28

Natural tooth or implant abutment that is located between terminal abutments that serve to support a fixed or removable dental prosthesis

Answer 28

Intermediate abutment

Question 29

When should a conventional (long span) FDP be avoided? What could happen?

Answer 29

When a pier abutment is present; creates stress on terminal and pier abutments

Question 30

What are the following complications of?

Rocking of retainers
Bending of FDP
Tensile forces btwn retainers & abutments
Intrusion of pier abutments
Margin microleakage

Answer 30

Pier abutments

Question 31

What is the ideal treatment option when you have to work around a pier abutment?

Answer 31

Implant