Lecture 2 Flashcards
Occlusal Forces - WHat is the max range of occlusal forces in the mouth?
200 - 3500N Forces on 1st & 2nd molars vary from 400-800N
Are occlusal forces bigger in anterior or posterior teeth?
Posterior teeth obviously!
What is the average force on the bicuspids, cuspids and incisors?
Bicuspids - 300 Cuspids (Canine) - 200 Incisors - 150
What are 4 factors that effect occlusal forces?
-age -anatomic location -occlusal scheme -placement of dental prosthesis
Define STRESS
Stress - when a force acts on a constrained body, the force is rested by the body and the internal reaction is equal in magnitude and opposite in direction to the applied external force is call stress
What is the equation for Stress and why are stress and force not the same?
S = F/area Not the same because….?
Name the 4 types of stress
- Axial (straight or compressive) 2. Shear (tearing or parallel) 3. Bending 4. Torsional The 2 basic types are axial and shear
Define Tensional stress
2 sets of forces directed AWAY from each other (being pulled apart)
Define Strain
Deformation in a body due to stress
Define each label on the stress strain curve
A. = Proportional limit: deals with the proportionality of strain to stress in the structure
B = elastic limit (point to which material can be stretched but still return to normal)
C = Plastic limit (the point of no return)
D = Ultimate tensile strength
What is Yield strength?
Y: a small defined amount of permanent deformation has occurred in the material
this amount of permanent strain is indicated as 0.2%
Define Ultimate Strength
(UTS) Maximum stress a material can withstand before failure in tension
ALSO
(Ultimate Compressive Strength) (UCS)
Maximum stress a material can withstand in COMPRESSION before failure
Define Fracture strength or fracture stress
Point at which material fractures
Define Resilience
Resistance of a material to PERMANENT Deformation
Define Toughness
Resistance to material to fracture
