Comprehensive Exam Material Flashcards
When do we use an S curve?
In class II prep
Purpose of an S curve:
- keeps the narrow isthmus away from the axiopulpal line angle
- allows the preparation to break buccal contact
- creates a smooth and rounded outline
- allows the buccal wall to be 90 degrees to the cavosurface margin
Exposes the ends of enamel rods for a strong bond and gives a better seal
gingival bevel
Why do we place a gingival bevel?
exposes ends of enamel rods for stronger bond and better seal
Where do we place a gingival bevel?
at axiopulpal line angle
When we place the gingival bevel at the axiopulpal line angle, this allows for:
increased resistance to fracture of isthmus of restoration
What is the most common cause of fracture at the isthmus of a class II?
Lack of gingival bevel
When and why would we extend margins of the box portion of preparation?
Sharp axiopulpal line angle (this is why we bevel it)
Appropriate exit angles of buccal, lingual, and gingival walls of amalgam:
90 degrees on all
Appropriate exit angles of buccal, lingual, and gingival walls of composite:
buccal & lingual- flare greater than 90 degrees
gingival- 90 degrees
when would you not need to place a gingival bevel?
once you get into deeper preparations when enamel is extremely thin or you’re into dentin or cementum (bc no enamel rods are present here)
Where do you place retention grooves in a box?
-buccal-axial line angle and lingual-axial line angle
- just inside the DEJ, entirely in dentin
When placing a retention groove into a box, the groove does not go into the:
gingival floor
Label this photo:
A: gingival-axial line angle
B: buccal-gingival line angle
C: buccal-gingival axial point angle
D: buccal axial line angle (w/optional retention groove)
E: axiopulpal line angle
F: lingual-axial line angle (w/optional retention groove)
G: lingual-gingival axial point angle
H: lingual-gingival line angle
List the advantages of composite resin: (6)
- esthetics
- conservation of tooth structure
- bonding
- no metal
- can be economical (vs. crown/ inlays/onlays)
- prep more forgiving (restoration is NOT!!!)
Why is it advantageous that composite resin involves bonding? (2)
- reduced micro leakage and recurrent decay
- increased retention
Why is it advantageous that composite resin does not incorporate metal? (3)
- no mercury discussion
- no corrosion
- no galvanic shock
List order of expense from least to greatest:
- crown & inlays/onlay
- amalgam
- composites
- amalgam
- composites
- crowns & inlays/onlays
What are the disadvantages of composite resin restorations? (9)
- low modulus of elasticity
- porous
- more technique sensitive placement
- more time-consuming placement
- microleakage
- pullback- can create voids
- expensive compared to amalgam
- can’t place in bulk
- can’t support occlusion
What do we mean by “composite cannot support occlusion”
must have tooth supported occlusion on marginal ridges and cusp tips)
What is the purpose of using a wedge in a class II preparation?
closes the margin at the gingival of the box and prevents overhang
When using a tofflemire retainer band the narrower opening faces:
gingivally
What way should the opening slits of the tofflemire face?
gingival
Why should the opening slits of the tofflemire face gingivally?
so when you release the tofflemire it comes off of the tooth towards the occlusal surface
How to troubleshoot errors in proximal box restorations: (2)
- choose correct wedge (size/shape) and properly seat it
- Properly condensing amalgam
Properly condensing amalgam prevents:
voids into point angles
Choosing the correct size and shape of wedge, as well as correct placement of wedges ensures:
good contour of gingival margin
This instrument should be used in a proximal box restoration to press and wiggle into internal line angles (BG and LG), against margin areas, and contact areas of the band.
Hollenback condenser
What instrument should be used for the pre-carve burnishing in an amalgam proximal box restoration?
side of hollenback condenser or large ball burnisher
What instrument should be used in a proximal box restoration for defining occlusal embrasure by using at a 45 degree angle
explorer
An explorer can be used to define the occlusal embrasure of a proximal box restoration by holding at:
45 degree angle
What instrument is used for forming grooves and carving the marginal ridge in a proximal box amalgam restoration?
Hollenback carver
What instrument should be used to redefine the occlusal embrasure?
explorer
In a class II restoration what instrument should be used to-
A: carve excess off the buccal and lingual walls of box
B: break corner off of marginal ridge
C: carve embrasures
hollenback carver
In a class II restoration what instrument should be used to-
A: carve away gingival margin excess
B: instruments drawn laterally or occlusally
hollenback carver held obliquely OR wiland carver OR 34-35 jaquette scaler
In a class II restoration what instrument should be used when amalgam is partially set and need to adjust occlusion:
discoid carver
In a class II restoration what instrument should be used to redefine groove anatomy after doing final occlusal adjustment?
hollenback carver or cleoid carver
In a class II restoration what instrument should be used to smooth surfaces and bottom of grooves?
beavertail burnisher
Bond agent that does NOT require a separate etch step?
self etch
Requires etch, rinse, then bond agent:
total etch
When you only etch the enamel, avoiding dentin, (20-30s)
selective etch
A selective etch as opposed to a complete etch may:
reduce sensitivity
What should be avoided when doing a selective etch?
dentin
How long should the etch stay on in a selective etch?
20-30s
Etch placed all over the enamel and dentin:
complete etch
Describe the process of a complete etch:
- etch is placed over the enamel first for 20-30s
- etch is placed on the dentin for 15-20s
How should composite resin be placed?
incrementally not exceeding 2mm at a time (NO BULK FILL)
uncured layer of composite in which oxygen interferes with polymerization:
oxygen inhibited layer
When is the oxygen inhibited layer removed?
removed with finishing and polishing
The oxygen inhibited layer is a ____ thick layer which on the outside allows addition and wetting of subsequent layers of ____.
15 microns thick; composite
The oxygen inhibited layer just cured is ____ % ____ to co-polymerize with the new material
50% unreacted methacrylate groups
In an older restoration (no unreacted methacrylate groups), the repair strength =
50% original restoration (roughen with diamond)
Excavators and chisels are considered ____ instruments
cutting
Amalgam condensers, mirrors, probes, and explorers are considered ____ instruments
non-cutting
on the end of a non-cutting instrument, what is present?
face and nib
on the end of a cutting instrument, what is present?
Blade with cutting edge
Which instruments are best for different stages of carving anatomy:
- plastic instrument
- hollenback carver
- optrasculpt
instrument used to place and smooth composite on occlusal surface
plastic instrument
instrument used to carve anatomy, primarily used for amalgam
hollenback carver
instrument used to develop anatomy in composite resin prior to light curing:
optrasculpt
After light curing, what should be used to develop anatomy?
carbide burs (for finishing)
What is a “swivel”?
allows ergonomic manipulation of handpiece between dental unit
Where is the motor located in a handpiece?
motor located in actual handpiece
What is the purpose of water when drilling with a handpiece:
- cools are of contact between bur and tooth structure to prevent pulpal irritation
- avoids heat build up and destruction of odontoblastic processes in the dentin (dead tracts)
heat build up causing destruction of odontoblastic processes in the dentin leads to:
dead tracts
- uses steam under pressure
- 250 degrees F, 15 PSI, 20 min
- shelves for cassettes
autoclave
- oven-type sterilizer
- 320 degrees F, 60-120 mins
dry heat
- chemical vapor pressure
- use chemical solution in pressurized chamber
- 270 degrees F, 20-40 PSI, 20 min
- proper ventilation must be installed
chemiclave
- several hours BELOW 100 degrees Celcius
- proper ventilation must be installed
Ethylene oxide
Temp, pressure, and time requirements for autoclave sterilization:
250 degrees F, 15 PSI, 20 min
Temp and time requirement for dry heat sterilization:
320 degrees F for 60-120 min
Temp, pressure, and time requirements for chemiclave sterilization:
270 degrees F, 20-40 PSI, 20 min
Temp and time requirement for ethylene oxide sterilization:
several hours below 100 degrees C
the STATIC relationship between incising and masticating surface of the maxillary and mandibular teeth or tooth analogues
occlusion
the STATIC AND DYNAMIC contact relationship between occlusal surfaces of teeth during during function:
articulation
Occlusion can be described as a ____ relationship.
static
Articulation can be described as a ____ relationship.
static and dynamic
forces are directed over the long axes of teeth:
axial loading
In axial loading, forces are directed:
over the long axes of teeth
Type of contacts:
when each functional cusp occlusion in a fossa of the opposing tooth:
cup-fossa contacts