Biomechanics

Question 1

• Application of mechanical engineering principles in the living organism
• Mechanical forces exerted on RPD during functional & parafunctional mandibular movements should be properly directed to the supporting tissue to elicit the most favorable response.

Answer 1

Biomechanics

Question 2

Teeth better able to tolerate vertical forces: down ____ of tooth
–More PDL fibers activated to resist force

Answer 2

long-axis

Question 3

Excess force to alveolar bone may result in what 2 things?

Answer 3

Mucosal ulcerations

Bone resorption

Question 4

What are the 3 RPD components involved in retention?

Answer 4

Direct retainer: Retentive clasp
Indirect retainer
Proximal plates

Question 5

What 4 RPD components involved in stability?

Answer 5

Minor connectors
Proximal plates
Lingual plates
Denture bases

Question 6

What are the 3 RPD components involved in support?

Answer 6

Rests
Major connectors (Max tooth tissue supported)
Denture bases

Question 7

:is the means by which one part of a restoration is made to counter the effects created by another part.

Answer 7

Reciprocation

Question 8

RPD’s true reciprocation can only be achieved if the reciprocating element touches the tooth before or after the retentive clasp?

Answer 8

Before

Question 9

What class of RPDs best resist functional forces

Answer 9

Class III

Question 10

What are the 3 cases of RPD that are Tooth tissue supported

Answer 10

Class 1, 2 and long span IV

Question 11

What are the tooth supported classes of RPD?

Answer 11

Class III and short span class IV

Question 12

Tooth tissue or tooth supported?
–Subject to greater stress
–Combination of tooth & soft tissue support
–RPD extension movement permits rotational movement around fulcrums in 3 planes

Answer 12

Tooth tissue supported

Question 13

What motion occurs through the sagittal plane through the horizontal plane fulcrum?

Answer 13

Rotation causing vertical dislodgement

Question 14

What motion occurs through the vertical plane through the longitudinal fulcrum?

Answer 14

Rocking side to side

Question 15

What motion occurs through the horizontal plane through the vertical fulcrum?

Answer 15

Horizontal twisting resulting in BL movement of RPD

Question 16

What class of lever do you need for an RPD?

Answer 16

Class 2

Question 17

What type of clasp causes a class 1 lever in distal extension cases?

Answer 17

Distal rest with circumferenial class

Question 18

What type of clasp causes class 2 lever in distal extension cases?

Answer 18

RPI or RPC with mesial rest

Question 19

Class ____ lever occurs when abutment with retentive clasp anterior to horizontal fulcrum line/axis of rotation (AR) in Class II arch with posterior modification space.

Answer 19

Class I Lever

Question 20

Is a broad or thin ridge provide better resistance to vertical and horizontal forces?

Answer 20

Broad ridge

Question 21

If the clasp is more flexible, how will it relate to stress on the abutment teeth, residual ridge, and horizontal stability?

Answer 21

Less stress to abutment
More stress to ridge
Less horizontal stability

Question 22

Does the retentive or reciprocal clasp arm contact the tooth first?

Answer 22

Reciprocal clasp