Chapter 10, 13, 18 Flashcards
The alloy powder portion of an amalgam capsule can contain which of the following?
a. Aluminum, tin, copper, and zinc
b. Silver, tin, copper, and zinc
c. Silver, platinum, tin, and zinc
d. Mercury, silver, copper, and tin
b. Silver, tin, copper, and zinc
Rationale:
The alloy powder portion of amalgam usually consists of silver, tin, and copper, with zinc, palladium, or indium being added in small quantities for specific qualities. Aluminum and platinum are not used in dental amalgam. Mercury is a liquid metal and therefore not contained in the alloy powder.
The type of amalgam that contains both round and lathe-cut particles is:
a. a hybrid.
b. an admix.
c. a lathe cut.
d. spherical.
b. an admix.
Rationale:
Admix amalgam contains a combination of both spherical and lathe-cut particles. Spherical amalgam contains spherical amalgam particles only, whereas lathe-cut amalgam contains only lathe-cut shavings. Hybrid is a type of composite.
All of the following are properties of high-copper amalgams except:
a. a low rate of corrosion.
b. creation of tin-copper compounds.
c. γ-2.
d. γ-1.
c. γ-2.
Rationale:
High-copper amalgams do not have a γ-2 phase, because copper reacts with the tin. This makes them superior in strength and gives them clinical longevity, a reduced rate of corrosion, and marginal integrity. Low corrosion, tin-copper compounds, and γ-1 phase are all properties of high-copper amalgams that make them superior to low-copper amalgams.
Mercury from ingested amalgam particles is not absorbed well and is usually excreted.
a. True
b. False
a. True
Your next patient is scheduled for a distal occlusal (DO) amalgam due to deep distal decay on #30. Which matrix band would be the best choice?
a. Universal matrix band
b. Sectional matrix
c. MOD band
d. None of the above
c. MOD band
Rationale:
An MOD band has extensions to cover deep mesial and distal restoration preps. A universal band would likely be too short to cover the whole tooth and the deep preparation. Sectional matrix bands are used for composite resin restorations.
If you have a mercury spill you should use a vacuum to quickly contain it.
a. True
b. False
b. False
Amalgam can be disposed in bags marked biohazard.
a. True
b. False
b. False
The trap attached to the high-volume evacuation (HVE) suction is a way to reduce mercury exposure to those in the dental office.
a. True
b. False
b. False
What is the safe/acceptable amount of mercury exposure for the dental professional?
a. 05 mg/m3 per week
b. 2 g per day
c. 50 mg per day
d. 5.0 mg/m3 per week
a. 05 mg/m3 per week
Rationale:
The Occupational Safety and Health Administration has set the acceptable level of mercury exposure for those workers at .05 mg/m3 per week, in a 40-hour work week. 2 g per day is the average amount of mercury released from amalgam and is in relation to the patient’s exposure. 50 mg per day is not the recommended exposure amount. 5.0 mg/m3 per week is many times above the recommended amount.
Amalgam fractures can be repaired. Flowable composite resin can be used to fill in a gap at the margin of an amalgam to repair and extend its life.
a. Both statements are true.
b. Both statements are false.
c. The first statement is true; the second statement is false.
d. The first statement is false; the second statement is true.
a. Both statements are true
Which of the following amalgam types tends not to displace the matrix band in class II restorations, requiring a larger wedge to separate the teeth more for good proximal contact?
a. Admix
b. Spherical
c. Lathe-cut
d. All of the above
b. Spherical
Rationale:
Spherical amalgams do not have much resistance to condensation and therefore tend not to displace the matrix band in class II restorations, requiring a larger wedge to separate the teeth more for good proximal contact. Admix amalgams do not have this issue.
When opening the sterilizer, a person should stand at least an arm’s length away to avoid inhaling any mercury vapors that may be released from instruments that were used in amalgam procedures.
a. True
b. False
a. True
The final setting time for amalgam is:
a. 1 hour.
b. 6 hours.
c. 8 hours.
d. 24 hours.
d. 24 hours.
Rationale:
While some amalgams can reach 50% of their final strength within an hour after placement, most amalgams take 24 hours to reach maximum strength and final set. Incorrect trituration and mixing times can alter setting times.
Amalgam should be polished immediately following placement to ensure a smooth surface that will not retain biofilm. Final polishing of composite should be done with an aluminum oxide polishing paste.
a. Both statements are true.
b. Both statements are false
c. The first statement is true; the second statement is false.
d. The first statement is false; the second statement is true.
d. The first statement is false; the second statement is true.
Rationale:
Amalgam must set for 24 hours before it reaches its final set and should not be polished before then. The final polishing step for composites should be done with a submicron aluminum oxide polishing paste.
Finishing and polishing can cause aerosol hazards.
a. True
b. False
a. True
Which of the following abrasives is used to prepare restorations for final cementation?
a. Aluminum oxide
b. Silicon carbide
c. Diamond
d. Tin oxide
a. Aluminum oxide
Rationale:
Aluminum oxide has a Moh’s rating of 9 and is a synthetic abrasive used to sandblast restorations in preparation for final cementation. Silicon carbide is used on disks as a beginning step of polishing restorations. Diamonds are used to prep teeth for crown and bridge procedures, as well as to finish and polish composite restorations in finer degrees. Tin oxide is very fine and is used as a polishing agent for enamel and restorations.
Abrasives are all naturally occurring substances for biocompatibility.
a. True
b. False
b. False
A toothbrush and mild cleansing agent are sufficient to remove most plaque and stains from dentures.
a. True
b. False
a. True
Prophy paste is a universal abrasive for cleansing that can be used on all restorations and tooth surfaces.
a. True
b. False
b. False
All of the following affect the rate of abrasion except:
a. irregularity.
b. pressure.
c. expiration date.
d. speed.
c. expiration date.
Rationale:
The shelf/expiration date does not affect the rate of abrasion. The size, irregularity, and hardness of particles, as well as the number of particles, the speed, and the pressure at which they are applied, all affect the rate of abrasion.
- An occlusal composite restoration has been placed and there is composite material beyond the cavosurface margin over to the mesial marginal ridge. The process of removing this excess composite material is called _____________.
a. overhang
b. margination
c. flash
d. none of the above
b. margination
Rationale:
The process of removing restoration prematurities is called margination. Overhang is excessive material at the cervical cavosurface margin, usually found interproximally. If an overhang is not too severe, it can be corrected with margination. Flash is feather-like, excess material on occlusal and proximal surfaces.
You are polishing a substrate material with a Moh’s scale of 6. Ideally, in what range on the scale should the material you use to polish it be?
a. It doesn’t matter; use whatever you prefer.
b. 1-3
c. 3-6
d. 7-9
d. 7-9
Rationale:
These abrasives are lower in hardness than the substrate being abraded and therefore must be 1-2 Moh’s units harder. If the surface or substrate being abraded is harder than the abrasive, there will be little to no effect; therefore the clinician must choose an abrasive harder than the substrate. An abrasive of equal hardness will merely result in cleaning the surface.
Which of the following abrasives is not used intraorally?
a. Pumice
b. Tin oxide
c. Rouge
d. Sodium bicarbonate
c. Rouge
Rationale:
Rouge (iron oxide) is used on a rag wheel to polish precious and semiprecious metal alloys and is not used intraorally. Pumice is used to polish tooth structure and amalgam intraorally. Tin oxide is used to polish enamel and other restorations. Sodium bicarbonate is used intraorally for air polishing and is also found in toothpastes.
Which of the following is not a consideration when finishing and polishing?
a. Speed
b. Grit
c. Substrate
d. Patient preference
d. Patient preference
Rationale:
Patient preference is not a consideration when finishing and polishing. It is at the discretion of the operator to analyze the substrate material and select the appropriate abrasives. Speed, grit, and the substrate that is being finished and polished are all considerations that must be analyzed when choosing an abrasive and finishing/polishing.
Polishing is the final contouring of the restoration with abrasives. Finishing is the use of a series of abrasives from coarse to fine used to produce a smooth, esthetic surface.
a. Both statements are true.
b. Both statements are false.
c. The first statement is true; the second statement is false.
d. The first statement is false; the second statement is true.
b. Both statements are false.
Rationale:
Finishing is the final contouring of the restoration with abrasives. Polishing is the use of a series of abrasives from harder to finer to produce a smooth, esthetic surface.
Which of the following procedures does not produce wear?
a. Finishing
b. Polishing
c. Cleaning
d. Abrasion
c. Cleaning
Rationale:
Cleaning does not produce wear or scratching and is primarily used to mechanically remove biofilm. Finishing and polishing are procedures intended to produce selective and controlled wear via abrasion.
Aluminum oxide is the abrasive of choice for composite and amalgams.
a. True
b. False
b. False
Which of the following is a necessary criterion for a provisional restoration?
a. Contact
b. Correct contour
c. Correct occlusion
d. All of the above
d. All of the above
Rationale:
In order for a provisional restoration to be acceptable, it must have proper contour, contact, and occlusion. Failure to have these characteristics can lead to such problems as tooth migration, trauma from occlusion, and gingival irritation.
Using a triple tray to create a provisional restoration should result in near perfect occlusion. Using the triple tray is an indirect fabrication method.
a. Both statements are true.
b. Both statements are false.
c. The first statement is true; the second statement is false.
d. The first statement is false; the second statement is true.
c. The first statement is true; the second statement is false.
Rationale:
Using a triple tray to form a provisional restoration is a direct fabrication technique. Because the impression is taken before the tooth is prepped, it allows for the creation of a provisional with near perfect occlusion.
Acrylic provisional materials are easy to use because they come in automix dispensing units. They also have low shrinkage, allowing them to be removed from the patient’s mouth quickly before the material begins to give off too much heat.
a. Both statements are true.
b. Both statements are false.
c. The first statement is true; the second statement is false.
d. The first statement is false; the second statement is true.
b. Both statements are false.
Rationale:
Acrylic provisional materials come in a powder/liquid and must be carefully hand mixed chairside. They also tend to have high shrinkage and should not be removed too soon from the patient’s mouth. Once removed, they should be placed in a cup of water to minimize shrinkage while the polymerization process completes.
An intracoronal cement provisional is sufficient for an inlay preparation. These are usually made with glass ionomer to ensure retention of the provisional.
a. Both statements are true.
b. Both statements are false.
c. The first statement is true; the second statement is false.
d. The first statement is false; the second statement is true.
c. The first statement is true; the second statement is false.
Rationale:
Procedures requiring less extensive coverage, such as inlays, and endodontic procedures can be handled with provisional cement coverage. These are usually done with zinc oxide eugenol due to its temporary and soothing properties. Glass ionomer is a permanent cement and restorative material.
It is OK to leave some temporary cement behind so that the patient does not have to be anesthetized when placing the permanent restoration.
a. True
b. False
b. False
All of the following are benefits of using aluminum shell crowns except:
a. Good marginal coverage
b. Stretchable
c. Easily trimmed to size
d. Poor contact
d. Poor contact
Vacuum-formed plastic is the most common choice for multi-unit provisional techniques.
a. True
b. False
a. True
Your patient had tooth 8 avulsed, fractured 7 and 9 playing soccer, and is having a 3-unit bridge made. Which of the following provisional materials would be the best choice in this situation?
a. Bis-acrylic
b. Polycarbonate
c. Aluminum shell
d. All of the above
a. Bis-acrylic
Rationale:
Bis-acrylic composites have superior esthetics and can be used to fabricate multi-unit bridges. Polycarbonate comes in several shapes and sizes but is not ideal for multi-unit provisional coverage. Aluminum shell provisionals are for posterior provisional coverage.
You 6-year old patient has extensive decay on tooth B. Instead of extracting the tooth the dentist decides to place a provisional crown. Which material will this crown be made of?
a. Stainless steel
b. Acrylic resin
c. Aluminum shell
d. Bis-acryl
a. Stainless steel
It is not a problem if the provisional comes off because it’s only temporary.
a. True
b. False
b. False
The details of a provisional restoration do not matter, as long as the tooth structure is covered until the permanent restoration can be placed.
a. True
b. False
b. False
Anterior provisional restorations can be used as guides for permanent restorations.
a. True
b. False
a. True
Which of the following is not a characteristic of bis-acrylic provisional materials?
a. Biocompatible
b. Good strength
c. Good for long-span provisionals
d. Low shrinkage
c. Good for long-span provisionals
Rationale:
Although bis-acrylics have many ideal qualities such as low odor, less wear, and biocompatibility, they are too brittle to use for long-span provisionals.
