Operative Flashcards
Which of the following statements regarding
caries risk assessment is correct?
A. The presence of restorations is a good indicator of
current caries activity.
B. The presence of restorations is a good indicator of
past caries activity.
C. The presence of dental plaque is a good indicator
of current caries activity.
D. The presence of pit-and-fissure sealants is a good
indicator of current caries activity.
B. A restored tooth indicates potential past carious
activity but not current activity. Plaque presence
does not necessarily indicate caries presence
and sealants are used for preventive purposes,
not caries treatment
Which of the following statements about indirect
pulp caps is false?
A. Some leathery caries may be left in the
preparation.
B. A liner is generally recommended in the
excavation.
C. The operator should wait at least 6 to 8 weeks
before re-entry (if then).
D. The prognosis of indirect pulp cap treatment is
poorer than that of direct pulp caps.
D. When doing an indirect pulp cap some caries
may be left, a liner [probably Ca(OH)2] is usually
placed over the excavated area, and the area
may be assessed 6 to 8 weeks later. Regardless,
the indirect pulp cap prognosis is better than the
prognosis for direct pulp caps
Smooth surface caries refers to \_\_\_\_\_. A. Facial and lingual surfaces. B. Occlusal pits and grooves. C. Mesial and distal surfaces. D. A and C.
. D. Smooth surface caries occurs on any of the axial
(facial, lingual, mesial, and distal) tooth surfaces
but not the occlusal.
The use of the rubber dam is best indicated for \_\_\_\_\_. A. Adhesive procedures. B. Quadrant dentistry. C. Teeth with challenging preparations. D. Difficult patients. E. All of the above.
. E. The advantages and benefits of rubber dam
usage are reflected in all of the items stated. The
rubber dam isolation increases access and visibility.
For a dental hand instrument with a formula of
10-8.5-8-14, the number 10 refers to _____.
A. The width of the blade in tenths of a millimeter.
B. The primary cutting edge angle in centigrades.
C. The blade length in millimeters.
D. The blade angle in centigrades.
A. The first number is the width of the blade or primary
cutting edge in tenths of a millimeter (0.1
mm). The second number of a four-number
code indicates the primary cutting edge angle,
measured from a line parallel to the long axis of
the instrument handle in clockwise centigrades.
The angle is expressed as a percent of 360
degrees. The instrument is positioned so that this
number always exceeds 50. If the edge is locally
perpendicular to the blade, then this number is
normally omitted, resulting in a three-number
code. The third number (second number of a
three-number code) indicates the blade length in
millimeters. The fourth number (third number of
a three-number code) indicates the blade angle,
relative to the long axis of the handle in clockwise
centigrades
When placement of proximal retention locks in
Class II amalgam preparations is necessary,
which of the following is incorrect?
A. One should not undermine the proximal enamel.
B. One should not prepare locks entirely in axial
wall.
C. Even if deeper than ideal, one should use the
axial wall as a guide for proximal lock placement.
D. One should place locks 0.2 mm inside the DEJ to
ensure that the proximal enamel is not
undermined.
C. Retention locks, when needed in Class II amalgam
preparations, should be placed entirely in
dentin, thereby not undermining the adjacent
enamel. They are placed 0.2 mm internal to theDEJ, are deeper gingivally (0.4 mm) than
occlusally (i.e., they fade out as they extend
occlusally, and translate parallel to the DEJ). If
the axial wall is deeper than normal, the retention
lock is not placed at the axiofacial or axiolingual
line angles but, rather, is positioned 0.2 mm
internal to the DEJ. If placed at the deeper location,
it may result in pulp exposure, depending on
the location of the axial wall depth.
Choose the incorrect statement about Class V
amalgam restorations.
A. The outline form is usually kidney- or crescent-
shaped.
B. Because the mesial, distal, gingival, and incisal
walls of the tooth preparation are perpendicular
to the external tooth surface, they usually diverge
facially.
C. Using four corner coves instead of two full-length
grooves conserves dentin near the pulp and may
reduce the possibility of a mechanical pulp
exposure.
D. If the outline form approaches an existing
proximal restoration, it is better to leave a thin
section of tooth structure between the two
restorations (< 1 mm) than to join the
restorations.
D. Because of the typical shape of a carious lesion
in the cervical area, the resulting restoration is
kidney- or crescent-shaped and the extensions
are to the line angles, resulting in the mesial and
distal walls diverging externally. The convexity of
the tooth in the gingival one third results in the
occlusal and gingival walls diverging externally.
There are several retention groove designs that
are appropriate, including four corner coves,
occlusal and gingival line angle grooves, or circumferential
grooves. However, as with any
restoration, if there is only a small amount of
tooth structure (< 1 mm) between the new and
existing restoration, it is best to join the two
restorations together and prevent the possibility
of fracture of the small amount of remaining
tooth structure.
In the conventional Class I composite preparation, retention is achieved by which of the following features? 1. Occlusal convergence 2. Occlusal bevel 3. Bonding 4. Retention grooves A. 2 and 4 B. 1 and 3 C. 1 and 4 D. 2 and 3
B. Typically, the Class I composite preparation has
occlusally converging walls that provide primary
retention form. The actual bonding also provides
retention form. However, an occlusal bevel is not
indicated on Class I preparations nor are retention
grooves used
Many factors affect tooth/cavity preparation.
Which of the following would be the least
important factor?
A. Extent of the defect.
B. Size of the tooth.
C. Fracture lines.
D. Extent of the old material.
B. Obviously, a tooth preparation is dictated by the
extent of the carious lesion or old restorative
material, the creation of appropriate convenience
form for access and vision, and the anticipated
extensions necessary to provide an
appropriate proximal contact relationship.
Fracture lines present should normally be
377
Answer Key for Section 2
included in the restoration. However, it is rare
that the size of the tooth will affect the design of
the tooth preparation
- Which of the following statements about an
amalgam tooth/cavity preparation is true?
A. The enamel cavosurface margin angle must be 90
degrees.
B. The cavosurface margin should provide for a 90-
degree amalgam margin.
C. All prepared walls should converge externally.
D. Retention form for Class Vs can be placed at the
DEJ.
- B. Although the amalgam margin must be 90
degrees, the enamel margin may not be 90
degrees, especially on the occlusal surface. Most
walls converge occlusally, but many Class V
amalgam preparations have walls that diverge
externally. No retention form should be placed at
the DEJ; otherwise, the adjacent enamel will be
undermined and subject to fracture
Causes of postoperative sensitivity with amalgam restorations include all of the following except \_\_\_\_\_. A. Lack of adequate condensation, especially lateral condensation in the proximal boxes. B. Voids. C. Extension onto the root surface. D. Lack of dentinal sealing.
C. The primary causes of postoperative sensitivity
for amalgam restorations are voids (especially at
the margins), poor condensation (that may result
in a void), or inadequate dentinal sealing.
Extension onto the root surface does not necessarily
result in increased sensitivity
When carving a Class I amalgam restoration,
which statement is false?
A. Carving may be made easier by waiting 1 or 2
minutes after condensation before it is started.
B. The blade of the discoid carver should move
parallel to the margins resting totally on the
partially set amalgam.
C. Do not carve deep occlusal anatomy.
D. The carved amalgam outline should coincide with
the cavosurface margins.
. B. Amalgam carving should result in coincidence
with the cavosurface margin and should not
result in deep occlusal anatomy because such
form may create acute amalgam angles that are
subject to fracture. Depending on the condensation
rate of the amalgam used, waiting a couple
of minutes prior to initiating carving may allow
the amalgam to harden enough that the carving
will be easier and overcarving will be minimized.
When carving the occlusal cavosurface margin,
the discoid carver should rest on the adjacent
unprepared enamel, which will serve as a guide
for proper removal of amalgam back to the
margin.
The setting reaction of dental amalgam proceeds
primarily by _____.
A. Dissolution of the entire alloy particle into
mercury.
B. Dissolution of the Cu from the particles into
mercury.
C. Precipitation of Sn-Hg crystals.
D. Mercury reaction with Ag on or in the alloy
particle.
D. The trituration process mixes the amalgam components
and the reaction results in the alloy
particle being coated by mercury and a product
being formed.
Restoration of an appropriate proximal contact
results in all of the following except _____.
A. Reduction/elimination of food impaction at the
interdental papilla.
B. Provide appropriate space for the interdental
papilla.
C. Provide increased retention form for the
restoration.
D. Maintenance of the proper occlusal relationship.
C. Proper proximal contacts reduce the potential
for food impaction, thereby preserving the
health of the underlying soft tissue. A missing
proximal contact may result in tooth movement
that will have an adverse effect on the occlusal
relationship of the tooth. Having a correct contact
does not enhance the retentive properties of
the restorative material.
A major difference between total-etch and self-
etching primer dentin bonding systems include
all of the following except \_\_\_\_\_. A. The time necessary to apply the material(s). B. The amount of smear layer removed. C. The bond strengths to enamel. D. The need for wet bonding.
A. Self-etch dentin bonding systems differ from
total-etch dentin bonding systems by removing
less of the smear layer (they use a less potent
acid), creating a weaker bond to enamel (especially
nonprepared enamel), and not requiring
wet bonding that may be necessary for some of
the total-etch systems. Even though fewer
actual materials may be needed with some of
the self-etch systems, they need to be applied
in multiple coats and thus the time necessary
to apply the materials is similar for both
systems.
A casting may fail to seat on the prepared tooth
due to all of the following factors except _____.
A. Temporary cement still on the prepared tooth
after the temporary restoration has been
removed.
B. Proximal contact(s) of casting too heavy/tight.
C. Undercuts present in prepared tooth.
D. The occlusal of the prepared tooth was under-
reduced.
D. Occlusal reduction would not affect the ability
to seat a casting. However, temporary cement,
heavy proximal contacts, or tooth undercuts
could keep the casting from seating completely
All of the following reasons are likely to indicate
the need for restoration of a cervical notch
except _____.
A. Patient age.
B. Esthetic concern.
C. Tooth is symptomatic.
D. Deeply notched axially.
A. If a patient has a notched cervical area that is
very sensitive or very esthetically objectionable,
restoration is usually indicated. If the notched
area is very deep, adverse pulpal or gingival
responses may occur. Although more notched
areas are encountered in older patients, a
patient’s age is not a factor in the need for
restoration
All of the following statements about slot-
retained complex amalgams are true
except _____.
A. Slots should be 1.5 mm in depth.
B. Slots should be 1 mm or more in length.
C. Slots may be segmented or continuous.
D. Slots should be placed at least 0.5 mm inside the
DEJ.
A. The longer a slot, the better. They should be
inside the DEJ and prepared with an inverted
cone bur to a depth of 1 mm
Which one of the following acids is generally
recommended for etching tooth structure?
A. Maleic acid
B. Polyacrylic acid
C. Phosphoric acid
D. Tartaric acid
E. Ethylenediaminetetraacetic acid (EDTA)
C. Although some of the self-etch bonding systems
use milder acid, the primary acid system used for
etching tooth structure is phosphoric acid.
Triturating a dental amalgam will _____.
A. Reduce the size of the alloy particles.
B. Coat the alloy particles with mercury.
C. Reduce the crystal sizes as they form.
D. Dissolve the alloy particles in mercury.
B. Triturating (mixing) the amalgam particle with
the mercury is intended to result in coating the
particles with a surface of mercury and creating
the desirable phases in the set amalgam. All of
the alloy particle is not dissolved in the mercury,
nor is the size significantly reduced.
Which of the following materials has the highest linear coefficient of expansion? A. Amalgam B. Direct gold C. Tooth structure D. Composite resin
D. Composite materials exhibit more dimensional
change (2.5 times greater than tooth structure)
when subjected to extreme changes in temperature
than do the other choices. Direct gold is
slightly higher than tooth structure, and amalgam
is about twice as high as tooth structure.
A cervical lesion should be restored if it is \_\_\_\_\_. A. Carious. B. Very sensitive. C. Causing gingival inflammation. D. All of the above.
. D. All of these factors indicate that a cervical lesion
should be restored. In addition, if the lesion is large
and the pulpal or gingival tissues are in jeopardy, it
should be considered for restoration
In comparison to amalgam restoration, composite restorations are \_\_\_\_\_. A. Stronger. B. More technique-sensitive. C. More resistant to occlusal forces. D. Not indicated for Class II restorations.
B. Composite restorations are more techniquesensitive
than amalgam restorations because the
bonding process is very specific (requiring
exact, correct usage of the various materials and
an isolated, noncontaminated field), and the
insertion and contouring of composites are
more demanding and time-consuming.
Composites are not stronger than amalgam and
have similar wear resistance compared to amalgams.
Composites are indicated for Class II
restorations
The one constant contraindication for a
composite restoration is _____.
A. Occlusal factors.
B. Inability to isolate the operating area.
C. Extension onto the root surface.
D. Class I restoration with a high C-factor.
B. The constant contraindication for using a composite
restoration is the inability to properly isolate
the operating area. Occlusal wear of
composite is similar to that of amalgam.
Extension onto the root surface may result in gap
formation with composite but also results in
initial leakage with amalgam, indicating that
there is no ideal material for root-surface
extended restorations. A high C-factor (Class I)
can be largely overcome by using (1) a liner
under the composite, (2) a filled adhesive, and
(3) incremental insertion of the composite.
Which of the following statements is true
regarding the choice between doing a composite
or amalgam restoration?
A. Establishing restored proximal contacts is easier
with composite.
B. The amalgam is more difficult and technique-
sensitive.
C. The composite generally uses a more
conservative tooth/cavity preparation.
D. Amalgam should be used for Class II restorations.
C. The restoration of a proximal contact is easier
with amalgam than composite. Amalgam is easier
to use and is less technique-sensitive. Either
material can be used for Class II restorations.
Because an amalgam restoration requires a tooth
preparation that has (1) a specified depth(for strength of the amalgam), (2) cavosurface
marginal configurations that result in 90-degree
amalgam margins, and (3) undercut form to its
walls or secondary retention form features, they
require more tooth structure removal than do
composite tooth preparations. Composite tooth
preparations require (1) removal of the fault,
defect, or old material; (2) removal of friable
tooth structure; and (3) no specific depths—they
are more conservative.
A good preventive and treatment strategy for dental caries would include \_\_\_\_\_. A. Limiting cariogenic substrate B. Controlling cariogenic flora C. Elevating host resistance D. All of the above
D. Altering the organism, its nutrients, and its
environment will all enhance prevention and treatment
objectives.
Which of the following statements regarding
caries risk assessment is correct?
A. The presence of restorations is a good indicator
of current caries activity.
B. The presence of restorations is a good indicator
of past caries activity.
C. The presence of dental plaque is a good
indicator of current caries activity.
D. The presence of pit-and-fissure sealants is a
good indicator of current caries activity.
B. A restored tooth indicates potential past carious
activity but not current activity. Plaque presence
does not necessarily indicate caries presence
and sealants are used for preventive purposes,
not caries treatment.
Which of the following is considered a reversible carious lesion? A. The lesion surface is cavitated. B. The lesion has advanced to the dentin radiographically. C. A white spot is detected upon drying. D. The lesion surface is rough or chalky.
C. When an alteration (a break in continuity) occurs
to the tooth surface from a carious attack, restoration
is usually necessary. When a lesion is evident
in the dentin with an x-ray, the lesion usually needs
a restoration
Which of the following statements about indi-
rect pulp caps is false?
A. Some leathery caries may be left in the
preparation.
B. A liner is generally recommended in the
excavation.
C. The operator should wait at least 6 to 8 weeks
before re-entry (if then).
D. The prognosis of indirect pulp cap treatment is
poorer than that of direct pulp caps.
D. When doing an indirect pulp cap, some caries
may be left, a liner (probably Ca[OH]2
) is usually
placed over the excavated area, and the area may
be assessed 6 to 8 weeks later. Regardless, the
indirect pulp cap prognosis is better than the
prognosis for direct pulp caps.
Smooth surface caries refers to \_\_\_\_\_. A. Facial and lingual surfaces B. Occlusal pits and grooves C. Mesial and distal surfaces D. Both A and C.
D. Smooth surface caries occurs on any of the axial
(facial, lingual, mesial, and distal) tooth surfaces
but not the occlusal.
A finishing bur has how many blades com-
pared to a cutting bur?
A. Fewer blades.
B. Same number of blades.
C. More blades.
D. Number of blades is unrelated to the bur type.
C. A finishing bur is designed to provide a smoother
surface and therefore has more blades than a
cutting bur. The increased blade numbers results
in a smoother cut surface.
The use of the rubber dam is best indicated for \_\_\_\_\_. A. Adhesive procedures B. Quadrant dentistry C. Teeth with challenging preparations D. Difficult patients E. All of the above
E. The advantages and benefits of rubber dam
usage are reflected in all of the items stated. The
rubber dam isolation increases access and
visibility
The reason to invert a rubber dam is _____.
A. To prevent the dam from tearing
B. To prevent the underlying gingival from
accidental trauma
C. To provide a complete seal around the teeth
D. All of above
. C. When the rubber dam edge around the tooth is
turned gingivally (inverted), it significantly
reduces the leakage of moisture occlusally,
thereby sealing around the tooth better and
resulting in a better isolated operating area
For a dental hand instrument with a formula
of 10-8.5-8, the number 10 refers to _____.
A. The width of the blade, in tenths of a millimeter
B. The primary cutting edge angle, in centigrades
C. The blade length, in millimeters
D. The blade angle, in centigrades
A. The first number is the width of the blade or
primary cutting edge in tenths of a millimeter(0.1 mm). The second number of a four-number
code indicates the primary cutting edge angle,
measured from a line parallel to the long axis of
the instrument handle in clockwise centigrades.
The angle is expressed as a percent of 360
degrees. The instrument is positioned so that
this number always exceeds 50. If the edge is
locally perpendicular to the blade, then this
number is normally omitted, resulting in a threenumber
code. The third number (second
number of a three-number code) indicates the
blade length in millimeters. The fourth number
(third number of a three-number code) indicates
the blade angle, relative to the long axis of the
handle in clockwise centigrade.
The tooth preparation technique for a Class I
amalgam on a mandibular first molar does not
include which of the following?
A. Maintaining a narrow isthmus width
B. Initial punch cut placed in the most carious pit
C. Establishment of pulpal depth of 1.5 to 2 mm
D. Orientation of bur parallel to the long axis of the
tooth
D. A tooth preparation for a mandibular molar
should have a narrow isthmus, should be initiated
in the most carious (or distal) pit, and
should establish the initial pulpal floor depth of
1.5 to 2 mm. However, it should be oriented
parallel to the long axis of the crown, which tilts
to the lingual. If prepared in the long axis of the
tooth, there is greater potential of weakening
the lingual cusps.
When placement of proximal retention locks in
Class II amalgam preparations is necessary,
which of the following is incorrect?
A. One should not undermine the proximal enamel.
B. One should not prepare locks entirely in the
axial wall.
C. Even if deeper than ideal, one should use the
axial wall as a guide for proximal lock
placement.
D. One should place locks 0.2 mm inside the DEJ
to ensure that the proximal enamel is not
undermined.
C. Retention locks, when needed in Class II amalgam
preparations, should be placed entirely in
dentin, thereby not undermining the adjacent
enamel. They are placed 0.2 mm internal to the
DEJ, are deeper gingivally (0.4 mm) than
occlusally (i.e., they fade out as they extend
occlusally), and translate parallel to the DEJ. If
the axial wall is deeper than normal, the retention
lock is not placed at the axiofacial or axiolingual
line angles but, rather, is positioned 0.2 mm
internal to the DEJ. If placed at the deeper location,
it may result in pulp exposure, depending on
the location of the axial wall depth.
When the gingival margin is gingival to the CEJ in
a Class II amalgam preparation, the axial depth
of the axiogingival line angle should be _____.
A. 0.2 mm into sound dentin
B. Twice the diameter of a No. 245 carbide bur
C. 0.75 to 0.80 mm
D. The width of the cutting edge of a gingival
marginal trimmer
C. The guide for axial wall depth for a typical Class
II preparation that has a gingival margin occlusal
to the CEJ is 0.2 to 0.5 mm internal to the DEJ—
the greater depth is necessary when placing
retention locks. However, when there is no
enamel proximally, the axial wall needs to be
deep enough internally to provide for adequate
strength of the amalgam material as well as to
have room to place retention locks, if needed.
This depth is approximately 0.75 mm.
Choose the incorrect statement about Class V
amalgam restorations.
A. The outline form is usually kidney- or crescent-
shaped.
B. Because the mesial, distal, gingival, and incisal
walls of the tooth preparation are perpendicular
to the external tooth surface, they usually
diverge facially.
C. Using four corner coves instead of two full-
length grooves conserves dentin near the pulp
and may reduce the possibility of a mechanical
pulp exposure.
D. If the outline form approaches an existing
proximal restoration, it is better to leave a thin
section of tooth structure between the two
restorations (< 1 mm) than to join the
restorations.
. D. Because of the typical shape of a carious lesion in
the cervical area, the resulting restoration is
kidney- or crescent-shaped and the extensions
are to the line angles, resulting in the mesial and
distal walls diverging externally. The convexity of
the tooth in the gingival one-third results in the
occlusal and gingival walls diverging externally.
There are several retention groove designs that
are appropriate, including four corner coves,
occlusal and gingival line angle grooves, or circumferential
grooves. However, as with any
restoration, if there is only a small amount of tooth
structure (< 1 mm) between the new and existing restoration, it is best to join the two
restorations together and prevent the possibility of
fracture of the small amount of remaining
tooth structure
When preparing a Class III or IV composite
tooth preparation, which of the following is
false regarding placement of retention form?
A. Often involves gingival and incisal retention
B. Is placed at the axiogingival line angle
regardless of the depth of the axial wall
C. May be needed in large preps
D. Is usually prepared with a No. 1/4 round bur
B. When needed for large restorations, retention
form usually consists of a gingival groove and
incisal cove prepared with a small round bur (No.
1/4). The placement of the groove or cove is
dependent on the DEJ, placing the retention 0.2
mm internal to the DEJ entirely in dentin. It is not
placed at the axiogingival or axioincisal line
angles if those line angles are deeper than ideal;
otherwise, the retention form may be too deep or
cause a pulpal exposure
In the conventional Class I composite prepara-
tion, retention is achieved by which of the
following features? 1. Occlusal convergence 2. Occlusal bevel 3. Bonding 4. Retention grooves A. 2 and 4 B. 1 and 3 C. 1 and 4 D. 2 and 3
B. Typically, the Class I composite preparation has
occlusally converging walls that provide primary
retention form. The actual bonding also provides
retention form. However, an occlusal bevel is not
indicated on Class I preparations, nor are retention
grooves utilized
The success of an amalgam restoration is
dependent on all of the following features of
tooth/cavity preparation except _____.
A. Butt-joint cavosurface margin that results in a
90-degree margin for the amalgam
B. Adequate tooth removal for appropriate strength
of the amalgam
C. Divergent (externally) preparation walls
D. Adequate retention form features to mechanically
lock the amalgam in the preparation
C. A successful amalgam restoration requires
90-degree amalgam margins. Amalgam margins
less than 90 degrees result in increased potential
for fracture of the amalgam. Greater than
90-degree amalgam margins are good for the
amalgam but the corresponding enamel margin
will be less than 90 degrees and therefore potentially
undermined and have potential for fracture.
Since the amalgam is not bonded to the tooth, it
must be retained in the tooth with undercuts,
either in the primary or secondary preparation. An
amalgam restoration needs a minimum of
1-mm thickness in nonstress areas and 1.5 to 2
mm in areas that may be under load. Therefore,
the preparation must provide this dimension.
Except for Class V amalgams, the prepared walls
generally converge to the exterior. Thus, the prepared
walls may diverge or converge externally
Many factor affect tooth/cavity preparation.
Which of the following would be the least
important factor?
A. Extent of the defect
B. Size of the tooth
C. Fracture lines
D. Extent of the old material
B. Obviously, a tooth preparation is dictated by the
extent of the carious lesion or old restorative
material, the creation of appropriate convenience
form for access and vision, and the anticipated
extensions necessary to provide an
appropriate proximal contact relationship.
Fracture lines present should normally be
included the restoration. However, it is rare that
the size of the tooth will affect the design of the
tooth preparation
Which of the following statements about an
amalgam tooth/cavity preparation is true?
A. The enamel cavosurface margin angle must be
90 degrees.
B. The cavosurface margin should provide for a
90-degree amalgam margin.
C. All prepared walls should converge externally.
D. Retention form for Class Vs can be placed at the
DEJ.
. B. Although the amalgam margin must be
90 degrees, the enamel margin might not be 90
degrees, especially on the occlusal surface. Most
walls converge occlusally, but many Class V
amalgam preparations have walls that diverge
externally. No retention form should be placed at
the DEJ; otherwise, the adjacent enamel will be
undermined and subject to fracture.
A “skirt” feature for a gold onlay preparation
_____.
A. Has a shoulder gingival margin design
B. Is prepared by a diamond held perpendicular to
the long axis of the crown
C. Is used only for esthetic areas of a tooth
D. Increases both retention and resistance forms
D. A skirt is a “mini-crown” preparation around a line
angle. It should be prepared by a diamond
instrument in the long axis of the tooth crown,
extended to the gingival one-third, and result in an appropriate amount of tooth removal. It is placed
to increase both retention form (having opposing
skirt vertical walls retentive with each other) and
resistance form (enveloping the line angles like a
barrel hoop around a barrel). It extends the outline
form and therefore may be least appropriate for
highly esthetic areas in the mouth
Causes of postoperative sensitivity with amal-
gam restorations include all of the following
except _____.
A. Lack of adequate condensation, especially
lateral condensation in the proximal boxes
B. Voids
C. Extension onto the root surface
D. Lack of dentinal sealing
C. The primary causes of postoperative sensitivity for
amalgam restorations are voids (especially at the
margins), poor condensation (that may result
in void), or inadequate dentinal sealing.
Extension onto the root surface does not necessarily
result in increased sensitivity.
Factors that affect the success of dentin bond-
ing include all of the following except _____.
A. Dentin factors such as sclerosis, tubule
morphology, and smear layer
B. Tooth factors such as attrition, abrasion, and
abfraction
C. Material factors such as compressive and tensile
strengths
D. C-factor considerations
C. Tensile and compressive strengths may have relevance
for composite materials but not for dentin
bonding systems. The success of bonding is
dependent on the various dentin structural factors,
tooth factors, polymerization shrinkage,
C-factor considerations, and technique sensitivity
When carving a Class I amalgam restoration,
which statement is false?
A. Carving may be made easier by waiting 1 or
2 minutes after condensation before it is started.
B. The blade of the discoid carver should move
parallel to the margins resting on the partially set
amalgam.
C. Do not carve deep occlusal anatomy.
D. The carved amalgam outline should coincide
with the cavosurface margins.
B. Amalgam carving should result in coincidence
with the cavosurface margin and should not
result in deep occlusal anatomy because such
form may create acute amalgam angles that are
subject to fracture. Depending on the condensation
rate of the amalgam used, waiting a couple of
minutes prior to initiating carving may allow the
amalgam to harden enough that the carving will
be easier and overcarving will be minimized.
When carving the occlusal cavosurface margin,
the discoid carver should rest on the adjacent
unprepared enamel, which will serve as a guide
for proper removal of amalgam back to the margin
It is generally accepted that the maximum
thickness of a composite increment that allows
for proper cure is _____.
A. 1–2 mm.
B. 2–4 mm.
C. 4–6 mm.
D. There is no maximum thickness restriction.
. A. Generally, composite can be properly polymerized
in 1- to 2-mm increments
The setting reaction of dental amalgam pro-
ceeds primarily by _____.
A. Dissolution of the entire alloy particle into
mercury
B. Dissolution of the Cu from the particles into
mercury
C. Precipitation of Sn-Hg crystals
D. Mercury reaction with Ag on or in the alloy
particle
D. The trituration process mixes the amalgam components
and the reaction results in the alloy particle
being coated by mercury and a product
formed.
What is the half-life of Hg in the human body? A. 5 days B. 25 days C. 55 days D. 85 days E. 128 days
C. Fifty-five days is the half-life of mercury in the
body
Restoration of an appropriate proximal con-
tact results in all of the following except _____.
A. Reduction/elimination of food impaction at the
interdental papilla
B. Provides appropriate space for the interdental
papilla
C. Provides increased retention form for the
restoration
D. Maintenance of the proper occlusal relationship
C. Proper proximal contacts reduce the potential for
food impaction, thereby preserving the health of
the underlying soft tissue. A missing proximal
contact may result in tooth movement that will
have an adverse effect on the occlusal relationship
of the tooth. Having a correct contact does not
enhance the retentive properties of the restorative
material
The best way to carve amalgam back to occlusal cavosurface margin is to \_\_\_\_\_. A. Use visual magnification B. Use a discoid-cleoid instrument guided by the adjacent unprepared enamel C. Make deep pits and grooves D. Use a round finishing bur after the amalgam has set
B. Using the adjacent unprepared enamel at the
cavosurface margin to guide the discoid carving
instrument when carving away excess amalgam
at the occlusal margin is the best way to develop
the junction correctly
A major difference between total-etch and self-
etching primer dentin bonding systems include
all of the following except \_\_\_\_\_. A. The time necessary to apply the material(s) B. The amount of smear layer removed C. The bond strengths to enamel D. The need for wet bonding
A. Self-etch dentin bonding systems differ from totaletch
dentin bonding systems by removing less of
the smear layer (they use a less potent acid), creating
a weaker bond to enamel (especially nonprepared
enamel), and not requiring wet bonding
which may be necessary for some of the total-etch systems. Even though fewer actual materials may
be needed with some of the self-etch systems, they
need to be applied in multiple coats and therefore
the time necessary to apply the materials is similar
for both systems
Which of the following statements is not true
regarding bonding systems?
A. Even though dentin bonding occurs slowly, it
results in a stronger bond than to enamel.
B. Enamel bonding occurs quickly, is strong, and is
long-lasting.
C. One-bottle dentin bonding systems may be
simpler but are not necessarily better.
D. Dentin bonding is still variable because of
factors such as sclerosis, tubule size, and tubule
location.
A. Dentin bonding in laboratory studies may create
bond strengths similar to or greater than bond
strengths to enamel. However, clinical studies
cannot corroborate that the dentin bond is
stronger. In fact, the bond may deteriorate over
time. Sufficient information is not available to
accurately predict the bond potential to dentin in
every application. Bonding to enamel, however,
is predictable and good. The attempt to simplify
the bonding mechanism has resulted in less
materials being involved and less decision making
on the part of the operator—both in an effort
to get more predictable results. However, the
newer bonding systems have not yet been
proven to be better
A casting may fail to seat on the prepared
tooth due to all of the following factors except
_____.
A. Temporary cement still on the prepared tooth
after the temporary restoration has been
removed.
B. Proximal contact(s) of casting are too heavy or
too tight.
C. Undercuts present in prepared tooth.
D. The occlusal of the prepared tooth was under-
reduced.
D. Occlusal reduction would not affect the ability to
seat a casting. However, temporary cement, heavy
proximal contacts, or tooth undercuts could keep
the casting from seating completely
For a gold casting alloy, which of the following
is added primarily to act as a scavenger for
oxygen during the casting process?
A. Copper
B. Palladium
C. Silver
D. Zinc
D. Zinc is added to act as a scavenger for oxygen during
the casting process. Copper and palladium
increase the hardness and affect the color. Silver
has an effect on the color as well.
All of the following reasons are likely to indi-
cate the need for restoration of a cervical
notch except \_\_\_\_\_. A. Patient age. B. Esthetic concern. C. Tooth is symptomatic. D. Tooth is deeply notched axially.
A. If a patient has a notched cervical area that is very
sensitive or very esthetically objectionable, restoration
is usually indicated. If the notched area is very
deep, adverse pulpal or gingival responses may
occur. Although more notched areas are encountered
in older patients, a patient’s age is not a factor
in the need for restoration
When comparing pin retention with slot reten-
tion for a complex amalgam restoration, which
of the following statements is false?
A. Slots are used where vertical walls allow
opposing retention locks.
B. Slots provide stronger retention than pins.
C. Slots and grooves can be used interchangeably.
D. Pin retention is used primarily where there are
few or no vertical walls.
. B. Slots and pins may be used interchangeably.
They both provide good secondary retention form.
Slots are usually better when there exist box forms
or vertical walls in the preparation, and pins are
usually better when there are few or no vertical
walls. The retention is similar for both.
All of the following statements about slot-
retained complex amalgams are true except
_____.
A. Slots should be 1.5 mm in depth.
B. Slots should be 1 mm or more in length.
C. Slots may be segmented or continuous.
D. Slots should be placed at least 0.5 mm inside
the DEJ.
A. The longer a slot, the better. They should be
inside the DEJ and prepared with an inverted
cone bur to a depth of 1 mm
Bonding of resins to dentin is best described as involving \_\_\_\_\_. A. Mechanical interlocking B. Ionic bonding C. Covalent bonding D. Van der Waals forces
A. The bond of adhesives to dentin (and enamel) is
primarily a mechanical interlocking of the material
within the dentin (or enamel). The etching causes
some removal of the surface, creating irregularities
or spaced collagen fibrils into which the adhesive
enters. When polymerized, the adhesive is
mechanically locked into the surface
Which one of the following acids is generally recommended for etching tooth structure? A. Maleic acid B. Polyacrylic acid C. Phosphoric acid D. Tartaric acid E. EDTA
C. Although some of the self-etch bonding systems
use milder acid, the primary acid system used for
etching tooth structure is phosphoric acid
The principal goals of bonding are _____.
A. Sealing and thermal insulation
B. Strengthening teeth and esthetics
C. Esthetics and reduction of postoperative sensitivity
D. Sealing and retention
E. Retention and reduction of tooth flexure
D. Bonding is primarily for sealing the dentin and
enhancing the retention of the restorative material
in the preparation. Esthetic benefits are a welcome
side benefit when using a composite restoration.
Thermal insulation is provided by the use of
composite as compared to amalgam but is not a benefit of the bonding. Bonding will not alter tooth
flexure under normal load but may better help
bond the unprepared tooth structure together.
Triturating a dental amalgam will _____.
A. Reduce the size of the alloy particles
B. Coat the alloy particles with mercury
C. Reduce the crystal sizes as they form
D. Dissolve the alloy particles in mercury
B. Triturating (mixing) the amalgam particle with
the mercury is intended to result in coating the
particles with a surface of mercury and creating
the desirable phases in the set amalgam. All of
the alloy particle is not dissolved in the mercury
and the size is not significantly reduced.
The primary contraindication(s) for the use of
a composite restoration is (are) _____.
A. Occlusal factors
B. Inability to isolate the operating area
C. Nonesthetic areas
D. Extension onto the root surface
B. The only constant contraindication for the use of
composite is when the operating area cannot be
properly isolated, thereby decreasing the potential
success of the bond
Which of the following materials has the high-
est linear coefficient of expansion?
A. Amalgam
B. Direct gold
C. Tooth structure
D. Composite resin
D. Direct gold and tooth structure have similar linear
coefficients of expansion. Amalgram exhibits
twice that expansion whereas composite
expansion would be even greater (2.5 times
greater than tooth structure)
The most common pin used in restorative procedures is a(an) \_\_\_\_\_. A. Friction-locked pin B. Cemented pin C. Amalgampin D. Self-threaded pin
D. Self-threaded pins are used by most operators,
when pin use is indicated.
A cervical lesion should be restored if it \_\_\_\_\_. A. Is carious B. Is very sensitive C. Is causing gingival inflammation D. All of the above
D. All of these factors indicate a cervical lesion
should be restored. In addition, if the lesion is
large and the pulpal or gingival tissues are in jeopardy,
it should be considered for restoration
With regard to the mercury controversy related
to the use of amalgam restorations, which
statement is incorrect?
A. There is lack of scientific evidence that
amalgam poses health risks to humans except
for rare allergic reactions.
B. Alternative amalgam-like materials (with low or
no mercury content) have promise about
mercury.
C. True allergies to amalgam rarely have been
reported.
D. Efforts are underway to reduce the
environmental mercury to which people are
exposed to lessen their total mercury exposure.
B. There are no known alternative low- or nomercury
systems that have been developed
which provide the same properties or clinical
performance as amalgam. The other statements
are true.
In comparison to amalgam restorations, com-
posite restorations are _____.
A. Stronger
B. More technique-sensitive
C. More resistant to occlusal forces
D. Not indicated for Class II restorations
B. Composite restorations are more techniquesensitive
than amalgam restorations because the
bonding process is very specific (requiring exact,
correct usage of the various materials and an isolated,
noncontaminated field), and the insertion
and contouring of composites are more demanding
and time-consuming. Composites are not
stronger than amalgam and have similar wear
resistance compared to amalgams. Composites
are indicated for Class II restorations.
Which of the following statements is true
regarding the choice between doing a compos-
ite or amalgam restoration?
A. Establishing restored proximal contacts is easier
with composite.
B. The amalgam is more difficult and technique-
sensitive.
C. The composite generally uses a more
conservative tooth/cavity preparation.
D. Only amalgam should be used for Class II
restorations.
C. The restoration of a proximal contact is easier with
amalgam than with composite. Amalgam is easier
to use and is less technique-sensitive. Either material
can be used for Class II restorations. Because an
amalgam restoration requires a tooth preparation
that has (1) a specified depth (for strength of the
amalgam), (2) cavosurface marginal configurations
that result in 90-degree amalgam margins, and (3)
an undercut form to its walls or secondary retention
form features, they require more tooth structure
removal than do composite tooth preparations.
Composite tooth preparations require (1) removal
of the fault, defect, or old material, (2) removal of
friable tooth structure, and (3) no specific depths—
they are more conservative.
Ph of enamel demineralization
5.5
Best predictor of caries
Past caries history
Which is least likely to predict future caries? Amount of sugar intake
Frequency of sugar intake
Amount of caries and restorations
Amount of sugar intake
3 factors that affect caries initiation:
substrate, bacteria, host susceptibity
Which of the following is the earliest clinical sign of a carious lesion? A. Radiolucency
B. Patient sensitivity
C. Change in enamel opacity
D. Rough surface texture
E.Cavitation of enamel
Change in enamel opacity
What is true of Strep. mutans?
• Can live in plaque
• Can live on gingival
• Can live in a child with no teeth
• Has to live on a non-shedding surface
Has to live on a non-shedding surface
Most cariogenic sugar
Sucrose
S.mutans adheres to the biofilm on the tooth by converting sucrose into an extremely adhesive substance called dextran
polysaccharide
First attachment molecule
Dextran
Mutans converts sucroseàdextran like long chain polysaccharides (glucans/fructans) using enzyme glucosyltransferase.
What helps in carious progression but it is not the primary inititator for caries?
Lactobacillus
What is the most important etiologic factor in getting caries?
Saliva pH
Refined sugar
Fluoride tx
saliva flow
Refined sugar
Know how to determine if a patient is a high caries risk?
Assessment
Early childhood caries affects?
Centrals and molars
What one of the following increasing in the US?
Root caries
New data regarding caries shows:
a. increase in smooth surf caries - wrong
b. increase in pit/fissure caries - wrong
c. smooth surf caries and pit/fissure caries is same - wrong
d. increase in root caries
increase in root caries
QUESTION: Best clinical determinant of root caries?
sensitivity to cold
sensitivity to sweets
soft spot on tooth
soft spot on tooth - visual & tactile methods are used for detect caries
Remineralized teeth are stronger than regular enamel. True or False
True
For a lesion in enamel that has remineralized, what most likely is true?
- The enamel has smaller hydroxyapatite crystals than the surrounding enamel
- The remineralized enamel is softer than the surrounding enamel
- The remineralized enamel is darker than the surrounding enamel
- The remineralized enamel is rough and cavitated
- The remineralized enamel is darker than the surrounding enamel
What’s the characteristic of a remineralized tooth/arrested caries?
Darker, harder, more resistant to acid or further decay/caries
Characteristic of a lesion that is remineralized:
black, dark, bright
black, dark, opaque
black, dark, cavitated
black, dark, opaque
Leathery brown-white lesion? acute, chronic, arrested
arrested
What is the most common site of enamel caries?
- pit and fissure
- at the contact point
- slightly incisor to contact
- slightly cervical to contact
• pit and fissure
Where does caries start? Apical to proximal contact.
Apical to proximal contact.
Most interproximal caries lesion happens where?
Just under/below the contact
A class II caries re: contact is
: Apical to contact
When do you restore a lesion? When there is cavitation When it’s half through enamel When it passes CEJ When you see it on x-ray
When there is cavitation
Tx of root surface caries, what kind of dentin should not be restored?
Eburnated dentin (Sclerotic dentin)
Smooth surface caries most likely due to?
Plaque
Where does fluoride work the best?
A. interproximal
B. Pit and fissure (I saw this somewhere and it said smooth surfaces, pit and fissure is prr/sealant)
C. Smooth surfaces
C. Smooth surfaces
Which of the following is a factor for smooth caries & sugar in-take?
Consistency (others were volume, and other option.) I’d think frequency tho
- Sticky consistency stays on the tooth longer, allowing bacteria to keep the pH lower longer
For occlusal caries, where is base & cone?
Triangle point is at enamel and base to dentin, dentin base to tip at pulp. (apex to the
pulp)
prolly bc tubules wider towards CEJ
What tooth is most likely to have occlusal caries?
Mandibular molar
Caries in children depend most on
amount, consistency, & time.
Pit and Fissure caries is described as two cones:
a. Two bases are pointing toward the pulp
b. Two apexes are pointing toward pulp»» in smooth surface (proximal caries)
c. One apex toward the pulp and one base toward DEJ
d. base of both triangles facing the DEJ
d. base of both triangles facing the DEJ
At the DEJ, diff btw smooth, occlusal, and interproximal caries pattern
smooth is conical
occlusal - apex at occlusal
interprox - apex at DEJ
Conical shaped caries w/ broad base with apex towards pulp is commonly seen in?
a. root caries
b. smooth caries
c. pit/fissure caries
b. smooth caries
Most likely dx indicator of pit and fissure caries is what?
Explorer catch
40 y pt w/ all 32 teeth. No cavities. Has stain & catch in pit of molar. what do you do?
a. Watch & observe
b. sealant
c. composite
a. Watch & observe
If a dentist seals a caries lesion on the tooth, what would be the most likely result?
- Arrest caries
- Extension caries
- Discoloration of tooth
- Micro-leakage
- Arrest caries
Radiographic decay most closely resemble which zone of carious enamel? Body zone, dark zone, translucent zone, surface zone
Body zone,
When looking at a radiograph, what zone of caries are you looking at?
Body zone Demineralization
If you feed a person through a tube, what happens to risk of caries
decreases
Mechanism of caries indicator:
indicator: enters the dentin & binds to the denatured collagen.
- A colored dye in an organic base adheres to the denatured collagen, which distinguishes between infected dentin & affected dentin
caries indicator only stains
infected dentin
What type of caries detection is the Difoti used for?
Class I Class II, Class III (detection of incipient, frank and recurrent caries)
demineralization
Diagnodent for which class of caries
Class I pit and fissure occlusal ONLY
Sensitivity theory –
hydrodynamic theory
Most commonly accepted theory of dentin sensitivity?
Hydrodynamic theory
- Postulates that the pain results from indirect innervation caused by dentinal fluid movement in the tubule that stimulates
mechanoreceptors near the predentin
DMFS stands for
decay missing filled surfaces (and includes third molars)
DMF index measures
how permanent dentition is affected by caries
DMFT measures
amount of tooth decay
DMFT is for ____________teeth
permanent (not third molars, not primary teeth)
Which race has a higher F in DMFT index?
White
Which ethiticity has most caries in kid population (highest caries incidence)?
Hispanics
Which population has the most number of UNRESTORED caries?
Blacks
Which of the following acronyms is only used for kids? PI, DEFT, DMF, OHI-S, etc
DEFT
Differences between 245 and 330 burs:
All other dimensions the same except for
length. Other options were shape, what angle they form.
- 245 bur is 3mm in length while 330 is 1.5mm.
Which bur do you use for peds? A.245 bur B.18 C.51
A.245
Which is best for occlusal convergence in a prep?
245 (169 is better for facial and lingual)
Diameter of 245 bur?
0.8 mm
What bur use for amalagam retention in class II? 245 or 330
245
Example of pear shape bur: 329, 330, 245 (330L)
- 245 = 330L = pear and elongated bur (tip is a cone)
Bur used that converges F and L walls? #245, 7901, 169
169 (tapered bur, 0.9 diameter)
- If 169 is not there, pick 245.
What bur do you use to shape convergent walls for amalgam
à 169
Burs for smoothing out preps? More flutes and shallow more flutes and deeper less flutes and shallow less flutes and deeper
More flutes and shallow
More # of blades on carbide burs –> what?
: SMOOTHER, DECREASED CUTTING EFFICIENCY
Which high speed bur gives a smoother surface?
Plain cut fissure bur = best cross cut fissure have a higher cutting efficiency
Bur used for polishing –
Carbide have more threads, STEEL FOR POLISH
What is the correct method of excavation of deep caries?
a. Large bur from periphery to the center
b. Large bur from center to periphery
c. Small bur from periphery to center
d. Small bur from center to the periphery
a. Large bur from periphery to the center
use the largest bur that fits, and go around the periphery and then towards the deepest
Rotary high speed, how many round per min?
200,000 RPM
- slowspeed goes 20-30k average, endo = usually 800
Chisel vs spoon application:
Chisels are intended primarily to cut enamels, but spoons remove caries & carve amalgams
What’s the difference between an enamel hatchet & gingival marginal trimmer?
Both chisels but GMT has curved blade and angled
cutting edge while Enamel HA has cutting edge in plane of handle
Main difference and advantage of using GMT instead of Enamel hatchet?
a. bi-angled cutting surface
b. angle of the blade
c. push/pull action instead of
b. angle of the blade
What do you not use to bevel an inlay prep?
a. enamel hatchet
b. ging marg trimmer
c. flame diamond bur
d. carbide bur
a. enamel hatchet
What do u not use when beveling gingival margins?
Tapered diamond
- Causes enamel fracture
QUESTION: How do you bevel occlusal floor (gave list of instruments)
• 13, 8
• 15, 80
• 15, 95
• 15, 80 (GMT)
What instrument would not be used to bevel the gingival margin of an MOD prep?
Enamel Hatchet
Proper pulpal floor depth using Bur 245?
3mm, so half of it is 1.5 mm which is proper pulpal floor depth
You did a prep with high speed + diamond bur and tooth is sensitive, what is it about bur and handpiece that it caused sensitivity?
A) Desiccation
B) Traumatized dentin
C) Heat
C) Heat
Most common pulpal damage from cavity prep – heat, dentin dessication
heat
What would cause displacement of odontoblastic processes? Thermal Dessication Mechanical Chemical
Thermal
What causes displacement of odontoblastic nuclei in the dental tubules? Thermal, mechanical, chemical, caries, dessication
Thermal
Pins in Amalgam:
Pins should be 2mm into dentin, 2mm within amalgam, and 1 mm from the DEJ (to be safe) with no bends in the pins.
Resistance for amalgam
1st = Flat floors, rounded angles (bevel in axiopulpal line angles)
retention for amalgam
1st = BL walls converge, 2nd = retention grooves/Occlusal dovetail
Acute mercury toxicity for dentists or subacute mercury poisoning symptoms, the first signs is:
nausea, other are muscle weakness
(hypotonia) and hair loss.
Most likely for amalgam to fail? Outline cavity design, poor condensation
Outline cavity design,
MOD amalgam with hole why?
poor condensation
- condensation removes mercury (gamma mercury removed)
Most common reason for Amalgam fracture occuring in a primary tooth:
Inadequate cavity prep (especially the isthmus area)
Most common reason for failed amalgam moisture contamination improper prep design improper titrutration improper condensation
improper prep design - not enough depth
- most likely depth (first), then outline form
Patient had occlusal amalgam on tooth #30 few weeks ago, one day the dude went to Chinatown and was having lunch with his
hommies. He bit down on something and the amalgam broke off. He came back to your office demanding how could this happen with a new
filling. What should be crossing your mind?
The prep was not deep enough.
Ideal cavo margin (margin between tooth and your prep) for amalgam
is 90 degree
Axial pulp should be?
0.2 - 0.5 into DEJ
How far do you extend the pulpal floor in class I amalgam cavity on primary dentition?
- 1mm into dentin
- Just into dentin
Just into dentin
(total prep should 1.5 mm so 1 mm for enamel & ~ 0.5 mm for dentin
Greatest wear on enamel of the opposing tooth: amalgam, porcelain, microfill, hybrid composite, Porcelain (zirconia)
Porcelain (zirconia)
Picture of a deep amalgam w/ overhang: What is wrong with marginal ridge of DO amalgam of #29? All of the following except ?
Occlusal wear, over carving, wedge not placed right,
OVERCARVED
Which tooth will the matrix band be a problem with when placing a two surface amalgam?
to give an idea of the anatomy of the region:
mesial on maxillary first molar b/c of the cusp of carabelli also
- mesial Of max 1st premolar (MOST DIFFICULT due to mesialdevelopmental grove, contact is harder) > Distal of max molar
How to account for mesial concavity on maxillary 1st premolar when restoring with amalgam: custom wedge acrylic within matrix normal matrix create overhang and recontour
custom wedge
Two class III lesions adjacent to each other (kissing lesion). Which one do you prep first & which will be filled first?
Prep larger 1st
,
Restore smaller 1st
More corrosion of amalgam is in which phase?
Tin-mercury phase (gamma 2 phase)
- Noble metals (gold, pd, platinum) are CORROSION RESISTANT while silver & tin erode
- most common corrosion products found with conventional amalgam alloys are oxides and chlorides of tin
- silver tarnish but copper & tin corrode
most common corrosion products in conventional amalgam
oxides and chlorides of tin
Zinc in amalgam, what is used for?
Decreases oxidation of other elements (deoxidizer)
- Zinc acts as a deoxidizer, which is an O2 scavenger that minimizes the oxides formation of other elements in the amalgam alloys during
melting.
What type of Mercury is in the dental office? Inorganic, elemental
elemental
For amalgam, the most toxic mercury is: Elemental mercery, ethyl mercury, methyl mercury
methyl mercury (organic mercury)
Type of mercury most hazardous to dentist health: methyl mercury, ethylmercury, inorganic mercury, elemental mercury
methyl mercury,
Amalgam large condenser with lateral condensation is used in what type of amalgam
Spherical
What type of amalgam needs to be condensed more?
Spherical
