Operative1 Flashcards
All Class Ill lesions should be filled with composite resin, because they are esthetically important.
• both the statement and the reason are correct and related
• both the statement and the reason are correct but not related
• the statement is correct, but the reason is not
• the statement is not correct, but the reason is correct
• neither the statement nor the reason is correct
neither the statement nor the reason is correct (Composite resin is not recommended for Class III lesions on the distal-lingual aspect of canines (use either amalgam or direct gold))
When two teeth adjacent to each other have Class III lesions, you should prepare ? first and fill ? first
- the larger one
* the smaller one
The ideal amount of dentin required between an amalgam restoration and the pulp for insulation is: • 0.5 mm • 1.0 mm • 2.0 mm • 3.0 mm
2.0 mm (1.0 - 1.5 mm is acceptable but not ideal)
Amalgam is a poor thermal insulator; this is why a base of either calcium hydroxide or zinc oxide-eugenol is placed under most amalgam restorations (to provide thermal protection).
patient comes in claiming that their holistic doctor told him that he has an allergy to mercury and needs only white fillings. Your best response is:
• there is no such thing as a mercury allergy; plus, there is no mercury in amalgam fillings
• you might have mercury allergy, but that is very rare; plus, there is no mercury in amalgam fillings
• there is no such thing as a mercury allergy; plus, with proper isolation and technique, your exposure will be minimal
• you might have a mercury allergy, but that is very rare; plus, with proper isolation and technique, your exposure will be minimal
you might have a mercury allergy, but that is very rare; plus, with proper isolation and technique, your exposure will be minimal
The amount of mercury remaining in dental amalgam after condensation directly affects:
(1) the porosity of the restoration,
(2) the compressive strength of the restoration,
(3) the corrosive resistance of the restoration,
(4) the surface finish of the restoration
Which of the following are similarities between amalgam Class II restorations and inlay Class II restorations? Select all that apply.
• occlusal isthmus width
• depth into dentin
• convergent walls on the occlusal surface
• axiopulpal line angle shape
• gingival wall form
• internal line angles
- occlusal isthmus width
- depth into dentin
- axiopulpal line angle shape
You would prefer your assistant overtriturate the amalgam rather than undertriturate it. This is because an overtriturated amalgam will still have optimal strength.
• both statements are true
• both statements are false
• the first statement is true, the second is false
• the first statement is false, the second is true
both statements are true
A properly triturated amalgam appears ?
shiny, wet, smooth, and homogeneous (The longer the trituration time, the smaller the setting expansion) (Remember: An overtriturated mix is preferable to an undertriturated mix)
If an amalgam “chips” when you are carving it, the reason for this is that the amalgam ?
was condensed after its working time had elapsed
Class V amalgam restorations rarely require retentive grooves, but if they are used, they are placed at the incisoaxial and gingivoaxial line angles.
• both statements are true
• both statements are false
• the first statement is true, the second is false
• the first statement is false, the second is true
the first statement is false, the second is true
The nonparallel mesial and distal walls of the class V preparation are ? to the transitional line angles
straight and parallel (The outline form for the classical Class V amalgam preparation is a deformed trapezoid (sometimes called “kidney-shaped’). The outline form is determined by the location and size of the carious area)
The occlusal and gingival walls of the Cl V preparation should be gently curved arcs as determined by ?. Note: These arcs should be as parallel to each other as possible
the contour of the free margin of the gingival tissue
If moisture is incorporated into an alloy that contains zinc, the water reacts with the zinc to produce hydrogen gas. The resulting pressure from the liberated gas produces severe expansion of the amalgam. This results in the following clinical manifestations:
- The amalgam protrudes from the cavity preparation
- Postoperative pain
- Excessive corrosion
The most important problem for amalgam restorations is that they have ?
different coefficients of thermal expansion/contraction
Delayed expansion of amalgam restorations is associated with which two factors?
• insufficient trituration and condensation
• high residual mercury
• the contamination of the amalgam by moisture during trituration and condensation
• the failure to use a cavity varnish
- insufficient trituration and condensation
- the contamination of the amalgam by moisture during trituration and condensation (this one is the principal cause of failures)
The tensile strength of amalgam is about ? of its compressive strength,
one-fifth to one-eighth
Amalgam is brittle and has a ? edge strength
low
Amalgam is a ? thermal conductor and a ? thermal insulator.
- high
* poor
High-copper amalgams exhibit ? clinically relevant creep or flow
no
You need a minimum thickness of ? mm (in axial areas) to 1.5 to 2 mm (in areas of occlusal contact) of Amalgam for adequate compressive strength
0.75
Proper condensation and carving makes an amalgam restoration stronger because it removes the mercury-rich matrix.
• both the statement and the reason are correct and related
• both the statement and the reason are correct but not related
• the statement is correct, but the reason is not
• the statement is not correct, but the reason is correct
• neither the statement nor the reason is correct
both the statement and the reason are correct and related
The most important consideration in the strength of the amalgam is the mercury content. If the mercury content exceeds ? a dramatic loss in strength results
55% (amalgam must contains less than 50% mercury)
Which phase of the amalgam reaction is prone to corrosion in clinical restorations? • gamma • gamma-one • gamma-two • gamma-three
gamma-two (the gamma-two phase is not present in the high-copper amalgams [Copper contents over 6%])
Amalgam has a coefficient of thermal expansion approximately ? that of tooth structure.
twice
When preparing a Class II amalgam restoration, all surface angles should be approximately 90 degrees.
However, the internal angles should be rounded.
• both statements are true
• both statements are false
• the first statement is true, the second is false
• the first statement is false, the second is true
both statements are true
90° angle = butt joint
Class II amalgam preps have ? retention and resistance form for both the proximal box and occlusal portion of the preparation
independent
When the facial (or lingual) extension is ? from the primary groove toward the cusp tip, reduction of the cusp(s) for amalgam capping is mandatory
two-thirds
When the facial (or lingual) extension is ? from the primary groove toward the cusp tip, reduction of the cusp(s) for amalgam capping is mandatory for the development of adequate resistance form. Note: The final restoration has to have restored cusps with a minimal thickness of ? of amalgam for functional cusps and ? of amalgam for nonfunctional cusps.
- two-thirds
- 2 mm
- 1.5 mm
Beveling the gingival cavosurface margin of the proximal box of a Class II amalgam preparation on a permanent tooth:
• should result in a long bevel
• is contraindicated because of the low edge strength of amalgam
• should remove unsupported enamel that may fracture
• is unnecessary since the tooth structure in this area is strong
should remove unsupported enamel that may fracture (The gingival cavosurface margin is beveled only if it is in the enamel. Beveling is not necessary if the gingival margin is within cementum)
Which tooth requires special attention when preparing the occlusal aspect for a restoration? • mandibular first bicuspid • mandibular second bicuspid • maxillary first molar • maxillary first bicuspid
mandibular first bicuspid (The bur should be tilted lingually to prevent encroachment on the facial pulp horn and also to maintain dentinal support of the lingual cusp)
All four walls of a Class I amalgam preparation should diverge slightly because divergence prevents undermining of the marginal ridges.
• both the statement and the reason are correct and related
• both the statement and the reason are correct but not related
• the statement is correct, but the reason is not
• the statement is not correct, but the reason is correct
• neither the statement nor the reason is correct
the statement is not correct, but the reason is correct (Only two walls of a Class I amalgam preparation should diverge, the mesial and distal. The buccal and lingual walls of a Class I amalgam preparation should be convergent)
For premolars, the distance from the margin of the mesial and distal wall to the proximal surface must not be less than ?. For molars this minimal distance is ?.
- 1.6 mm
* 2 mm
The matrix band should be removed after condensation of the amalgam but prior to the final carving of the restoration. This is because the wedge compensates for the thickness of the matrix band
• both the statement and the reason are correct and related
• both the statement and the reason are correct but not related
• the statement is correct, but the reason is not
• the statement is not correct, but the reason is correct
• neither the statement nor the reason is correct
both the statement and the reason are correct but not related (the true reason for carving after the removal of the band is to gain proper access to all margins of the amalgam restoration)
The matrix band should be ? into contact with adjacent teeth, this will help ensure contact.
burnished
- Postoperative sensitivity of amalgam may be caused by ?
* Marginal voids may be caused by ?
- inadequate condensation, or lack of proper dentinal sealing
- inadequate condensation, or amalgam breaking away from margins when carving
The diagonal slot opening on the Tofflemire matrix retainer (also called the Universal matrix system) is always placed facing the gingiva. This:
• permits easy separation of the retainer from the band in an occlusal direction
• allows for better contour of band to tooth
• allows for easier wedge placement
• is less harmful on the gingiva
permits easy separation of the retainer from the band in an occlusal direction (In addition, the larger circumference of the matrix band is always placed toward the occlusal surface of the tooth. This accommodates for the larger tooth circumference at the contact level)
The primary function of the matrix band is ?. Other functions include providing a rigid wall to condense filling material against, preventing excess filling material from going subgingivally, and to some extent, limiting moisture contamination during condensation.
• to restore anatomical contours and contact areas
When placing a matrix band for a Class II amalgam restoration, the gingivoocclusal width of the band should be trimmed to be ?
at least 1 mm greater than the expected marginal ridge height
Which of the following are true statements regarding the polishing of amalgam? Select all that apply.
• it reduces marginal discrepancy
• it should be done about 10 minutes after placement
• occlusion should not be checked prior to polishing
• it prevents tarnishing of the restoration
• it improves the appearance of the restoration
• it should be done with a dry polishing powder
• it reduces marginal discrepancy
• it prevents tarnishing of the restoration
• it improves the appearance of the restoration
The final finish of the amalgam restoration should not be done until after the amalgam is fully set. It should be delayed for at least 24 hours after condensation and preferably longer (24-48 hours)
Heat generation during polishing of amalgam must ?. The use of dry polishing powders and discs can easily raise the surface temperature above the 60°C (140°F) danger point. Thus, a wet abrasive powder in a paste form is the agent of choice. Note: Heat will not only damage the pulp but also draws mercury to the surface of the restoration and ? will result
- be avoided
* an inferior restoration
Final polishing of amalgam may be accomplished using ?
a rubber cup with flour of pumice followed by a high-luster agent, such as tin oxide
All of the following are true concerning a Class V amalgam preparation EXCEPT one. Which one is the EXCEPTION?
• the outline form is determined primarily by the location of the free gingival margin
• the mesial, distal, gingival, and incisal walls of the cavity preparation diverge outward
• the retention form is provided by the gingival retention groove along the gingivoaxial line angle and an incisal retention groove along the incisoaxial line angle
• a cervical clamp is usually necessary to retract gingival tissues
the outline form is determined primarily by the location of the free gingival margin (outline form is determined primarily by the location and size of the carious lesion.)
Which of the following statements in reference to amalgam is false?
• increased trituration time will increase compressive strength and decrease setting expansion
• a decrease in particle size will decrease compressive strength and increase setting expansion
• increased condensation pressure will increase compressive strength and decrease setting expansion
a decrease in particle size will decrease compressive strength and increase setting expansion (The smaller the particle size, the less the expansion)
