Quiz 2 Flashcards
Which type of wax is preformed with a thin sheet of aluminum foil between the layers?
Bite wafers
Bite wafers are another example of bite registration wax.
Which material should be used if a more durable impression material is needed for bite registration?
Zinc oxide–eugenol (ZOE)
ZOE has no resistance to bite closure.
How does an Automix mixing unit system aid in infection control?
Less time is spent cleaning and disinfecting guns and cartridges.
Which item is used to polish or trim custom trays, provisional coverage, dentures, and indirect restorations?
Dental lathe
How will a water temperature of 80° F (26.6° C) affect an alginate mix?
It will make the mix set faster.
What are the three classifications of impressions used in dentistry?
Preliminary, final, and occlusal, or bite registration
Which type of baseplate wax is softest?
Type I
What are preliminary impressions used to make?
Diagnostic models
Also used for provisional coverage and orthodontic appliances.
Which type of impression tray covers the anterior portion of the dental arch?
Section
After fabrication, when can a self-cured resin custom tray be used?
After the heat has dissipated
Why would a dentist request preliminary impressions?
To fabricate custom trays
Also used for diagnostic models and provisional coverage.
What causes air bubbles in a model?
Improper pouring of the impression
Alginate impressions must be poured within _____ so that distortion does not occur.
1 hour
How will gypsum material be affected if additional powder is added after mixing has begun?
Weaker
How are alginate impressions removed from the mouth?
Use one quick, snap-out motion.
What are the three curing stages of impression materials?
Initial set, final set, final cure
Which portion of the maxillary impression tray should be seated in the mouth first?
Posterior
Each of the following can be done to alleviate the gag reflex when taking alginate impressions except one. Which one is the EXCEPTION?
Have the patient sit upright with the head tilted backward.
Which type of dental wax is often used to form a wall or box around a preliminary impression when it is poured up?
Boxing wax
Which statement is correct regarding custom impression trays?
They can be constructed from resin.
A trimmed maxillary model will be _____ at the anterior portion, and the mandibular model will be _____ at the anterior portion.
pointed; rounded
How should alginate material be loaded into a maxillary impression tray?
Heavier in the anterior and labial areas
The shelf life of alginate material is approximately __ months.
12
What should be done to an impression before pouring?
Use a gentle stream of air to remove excess moisture.
Where should alginate and elastomer impressions be disinfected?
Before leaving the treatment area
What are advantages of the Automix system for elastomeric impression materials?
Homogenous mix of material without waste
Which irreversible hydrocolloid material is used most widely for preliminary impressions?
Alginate
What is the working time of normal-set alginate impression material?
2 minutes
Which technique listed would be incorrect when pouring an impression?
In large amounts
What is one advantage of having laboratory equipment and trained personnel in the dental office?
The dentist or private laboratory technician can handle larger cases.
Which of the following is an acceptable method for altering the setting time of alginate irreversible hydrocolloid impression material?
Change the water temperature.
What is an acceptable method for altering the setting time of alginate irreversible hydrocolloid impression material?
Change the water temperature.
Cooler water increases the setting time, while warmer water shortens it.
Which impression material is used when an extremely accurate final impression is essential?
Elastomeric.
Elastomeric materials have a rubbery quality that allows for distortion-free removal.
When should water be running through a model trimmer?
When trimming.
Water should be turned off when the model trimmer is not in operation.
Which type of reversible hydrocolloid material is the most viscous?
Tray.
Syringe material is the least viscous, while tray material is the most viscous.
How should a plaster mix not be manipulated?
Complete mix in 30 seconds.
A proper mix should be completed in 2 minutes and mixed slowly until smooth.
How is an alginate impression disinfected?
Spray the alginate with an intermediate-level disinfectant.
Other methods can cause dimensional changes or are ineffective.
Legally, who can take final impressions?
Dentist.
Final impressions are essential for fabricating restorations and must be taken by a licensed dentist.
What is an incorrect statement regarding safety precautions in the laboratory?
This is the appropriate place for eating and drinking in the dental office.
No eating or drinking is permitted in the laboratory area.
What does the term syneresis mean as it relates to alginate impression?
Water evaporates from the impression.
This process causes the impression to shrink.
What device holds maxillary and mandibular models in an occlusal relationship?
Articulator.
The articulator helps maintain the correct occlusal relationship during model work.
