Principles of tooth prep III Flashcards
Cements are strongest under _ forces
compressive
Cements are stronger under (shear/tensil) stresses
shear
Cements are weakest under what forces
tensile
What determines whether the cement will be under compressive or tensile forces
the prep
What are the three most common complications for a single crown
- Need for endo
- Porcelain fracture
- Loss of retention
Cement is placed under tensile forces when the TOC is (high/low)
high
Decreased taper subjects the cement to what forces
shear
Surface area pertains to (occlusal surface/axial walls)
axial walls
increased SA –> _ retention
increased
Partial coverage restorations must be bonded…
adhesively (due to less retention)
Increase FL width leads to (increase/decreased) resistance and why
decreased… larger arch of rotation
Increase FL width leads to (increase/decreased) retention
increase
To increase reisstance form you decide to decrease the TOC. This should be done where on the axial wall
apical 1.5 mm (Cervical portion of the walls)
T/F Prepping the occlusal form parallel to the original inclines has a significant impact on resistance
f- not very significant
The BEST way to increase resistance for of a tooth is to
decrease TOC in the cervical portion (more effective than grooves/boxes)
What are the guidelines for proper placement of axillary grooves and boxes
- Must draw with remainder of prep (have POI)
- Be parallel to each other
- Be 1mm coronal to the margin
When are BL grooves used
crowns on abutment teeth for RPD
The BL groove should be placed on the wall that is (least/most) tapered
least
Best POI for a crown follows
the long axes of the adjacent teeth
(monocular/binocular) vision can make a prep that is undercut look acceptable
binocular…. thus monocular should be the method used to check a prep
How can you check the POI of a bridge with a mirror
Place the mirror over one prep til the entire finish line can be seen then move the the next prep if the mirror angulation changes then you don’t have a POI
