Midterm review - dental materials (spring 2013)

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The completed impression forms a ____ reproduction of the teeth and tissues, and the replica or model forms a _____ replica of the teeth and tissues
A.. positive; negative
B. positive; negative
C. negative; positive
D. negative; negative

C. negative; positive

Which of the following is true of impression trays?
A. stock trays are made of plastic rather than metal and can be solid or perforated
B. plastic trays are inexpensive and are disposable, whereas metal trays are more expensive and must be cleaned and sterilized between uses.

B. plastic trays are inexpensive and are disposable, whereas metal trays are more expensive and must be cleaned and sterilized between uses

Which of the following is true for hydrocolloids in dentistry?
A. agar hydrocolloid is reversible hydrocolloid
B. when agar powder is mixed with water, it forms a glue-like suspension that entraps the water, making a colloidal suspension called gel
C. the main clinical use of reversible hydrocolloid is for impressions

A. Agar hydrocolloid is a reversible hydrocolloid

The temperature at which the hydrocolloid liquefies is not the same temperature at which is solidifies, a property is called:
A. agglutination
B. hysteresis
C. hydrophlic
D. hydrophobic

B. hysteresis

Which of the following is the most widely used dental impression material?
A. reversible hydrocolloid
B. irreversible hydrocolloid
C. addition silicone impression material
D. condensation silicone impression material

B. irreversible hydrocolloid

Which of the following is true for alginate hydrocolloid?
A. fast set alginate has a working time of 2-3 minutes
B. Adjusting the powder to water ratio is the best way to lengthen or shorten the setting time
C. alginate hydrocolloid should be removed slowly to prevent deformation of critical surfaces
D. Some moisture will be lost from the impression even in 100% humidity

D. some moisture will be lost from the impression even in 100% humidity

A property extended maxillary alginate impression tray will extend posteriorly enough to include:
A. hamular notch
B. retromolar pad
C. soft palate
D. uvula

A. hamular notch

Containers of alginate such as cans or plastic containers should be turned end over end a few times to decompress the powder and mix the ingredients. Alginate dust is potentially hazardous to inhale because it contains silicon dioxide in the diatomaceous earth fillers.
A. both statements are true
B. both statements are false

A. both statements are true

Alginates should be loaded into the tray in ______ increments as ______ as possible
A. large; quickly
B. large; slowly
C. small; quickly
D. small; slowly

A. large; quickly

For a maxillary alginate impression, the operator stands just ________ and retracts the corner of the mouth with the side of the tray while retracting the other corner of the mouth with the index finger of the other hand
A. in front of the patient at the 5 oclock position
B. in front of the patient at the 7 oclock position
C. behind the patient at the 1 oclock position
D. behind the patient at the 11 oclock position

D. behind the patient at the 11 oclock position

Ideally, an alginate impression should be poured within:
A. an hour
B. a day
C. a week
D. a month

A. an hour

Which of the following elastomers is the most hydrophilic?
A. polysulfides
B. polyethers
C. condensation silicones
D. addition silicones

B. polyethers

A vast majority of dies are made from:
A. epoxy
B. metal
C. gypsum
D. wax

C. gypsum

Which of the following impression materials has the smallest dimensional change on setting of all elastomeric and hydrocolloid impression materials?
A. polyether
B. polysulfide
C. addition silicone
D. condensation silicone

C. addition silicone

_______gloves should be used when mixing PVS putty
A. utility
B. nitrile
C. latex
D. vinyl

D. vinyl

The acid most commonly used to etch tooth structure for bonding procedures is:
A. phosphoric
B. hydrochloric
C. hydrofluoric
D. citric

A. phosphoric

All of the following statements about bonding to enamel are true EXCEPT one:
A. achieved by chemical bonding
B. achieved by micromechanical retention
C. achieved by resin tags penetrating porosities in the enamel and by locking into surface roughness
D. more reliable bond than the dentin bond

A. Achieved by chemical bonding
Bonding to enamel is not achieved by chemical bonding

Bonding to dentin:
A. is best accomplished when the dentin is kept moist after etching
B. is stronger when the dentin is well died after etching
C. is inhibited by formation of the hybrid layer

A. is best accomplished when the dentin is kept moist after etching

Outermost layer of uncut enamel is _______ and difficult to bond.

aprismatic

All of the following statements about resin bonding agents are true EXCEPT one:
A. they are dissolved in solvents that allow them to penetrate the water on the moist dentin
B. they seal the dentin by penetrating into etched dentin surfaces and tubules
C. they chemically bond to the dentin
D. they chemically bond to composite resins

C. they chemically bond to the dentin

Self etching bonding agents
A. use 35% phosphoric acid as the etchant
B. use acidic primers to etch the tooth structure
C. require rinsing after etching
D. generally etch enamel equally as well as dentin

B. use acidic primers to etch the tooth structure

Total etching bonding systems
A. may result in tooth sensitivity caused by over drying or over etching
B. do not require a separate etching and rinsing step
C. do not require drying of the primer
D. do not provide a good etch of uncut enamel

A. may result in tooth sensitivity caused by over drying or over etching

With the TOTAL ETCH SYSTEM when bonding to dentin, one of the following statements is true. Which one?
A. the dentin surface should be thoroughly dried after etching and rinsing
B. the surface of the etched, washed, and dried dentin should be "glistening"
C. once you have dried the etched surface, bonding is hopeless

B. surface of the etched, washed, and dried dentin should be "glistening"

Dentin sensitivity can be caused by
A. pressure changes in the column of fluid within the dentinal tubules
B. stimulation of odontoblastic processes within the dentinal tubules
C. open unsealed dentinal tubules
D. over etching or over drying of the dentin
E. all of the above

E. all of the above

The smear layer is ___________

a tenacious layer of cut tooth debris on the surface of enamel and dentin

All of the following statements about bonding to repair fracture porcelain on a crown are true EXCEPT:
A. the surface is cleaned and roughened
B. 10% phosporic acid is used for etching the porcelain
C. silane is applied after etching to enhance the bond of adhesive resins to the porcelain
D. composite resin is usually used to restore the fractured portion

B. 10% phosphoric acid is used for etching the porcelain

Which one of the following does NOT interfere with the formation of a good bond?
A. saliva on the etched enamel or dentin
B. oil lubricant from the handpiece
C. moist dentin after rinsing etchant off and lightly drying
D. flavoring agents in prophy paste

C. moist dentin after rinsing etchant off and lightly drying

Which one of the following is true regarding the bonding of amalgam to a cavity preparation?
A. only the enamel is acid etched
B. freshly mixed amalgam is condensed onto unset bonding resin
C. the bonding resin should be light cured
D. wax is rubbed on the inside of the matrix band to keep the band from being glued to the tooth by the bonding resin

B. freshly mixed amalgam is condensed onto unset bonding resin

When endodontic posts are bonded into root canals, the bonding agent should NOT be
A. self curing
B. light curing
C. dual curing
D. applied in a thin layer

NO LIGHT CURE!
B. light curing should not be used

All of the following are correct steps for bonding ortho brackets EXCEPT one:
A. the tooth surface is cleaned with pumice
B. the enamel is etched with 35% phosphoric acid for approximately 30 seconds
C. the enamel is rinsed and left slightly moist
D. a resin adhesive is often used to bond the bracket

C. the enamel is rinsed and left slightly moist

When bonding composite resin to metal that is exposed after the overlying porcelain has fractured, which one of the following is FALSE?
A. retention to the metal is enhanced by roughening the surface with a course diamond bur, by sandblasting, by electrochemically etching, or by tin-plating
B. bonding agents are not needed because the composite resin sticks to the metal
C. An opaque resin is applied before the composite resin to mask the metal and prevents a gray color from showing through the slightly translucent composite resin
D. light curing materials can be used

B. bonding agents are not needed because composite resin sticks to the metal
FALSE

Until 1970, which of the following groups of dental auxiliaries were allowed to perform intraoral functions in all states?
A. dental hygienists
D. registered dental assistants
C. certified dental assistants
D. dental assistants

A. dental hygienists

Silver paste was first mentioned as a restorative material for teeth by the:
A. chinese
B. greeks
C. romans
D. french

A. chinese
(in 659 AD)

The "amalgam war" was fought over:
A. mining rights in states in the western region of the united states
B. the price of silver in relation to tin and zinc
C. the value and safety of silver and dental amalgam
D. patent issues between france and england

C. the value and safety of silver dental amalgam

Which of the following restorative techniques was first introduced in 1955?
A. cohesive gold foil
B. cast gold inlays
C. acid etch technique
D. synthetic resins for denture bases

C. acid etch technique

Dr. Frederick McKay is credited with:

noting dental fluorosis in Colorado Springs

Since 2005, the American Dental Association (ADA) Seal of Acceptance is awarded to:
A. both professional and consumer products
B. professional but not consumer products
C. consumer but NOT professional products
D. neither professional nor consumer products

C. consumer but not professional products

Dental materials considered devices, as well as over-thec-counter products sold to the public, are subject to control and regulation of the ______ Center for Devices and Radiological Health
A. Centers for Disease Control and Prevention
B. Food and Drug Administration
C. Drug Enforcement Administration
D. Department of Human and Health Services

B. Food and Drug Administration

Which of the following statements is TRUE concerning the American Dental Association (ADA) Seal?
A. all dental products qualify for the Seal
B. the process typically requires at least 3 months for completion
C. the ADA Seal is usually awarded for the life of the product
D. products do not require evaluation when the composition of a previously accepted product is changed

B. the process typically requires at least 3 months for completion

The delivery of dental materials most often falls to:
A. the dentist
B. the dental hygienist
C. the dental assistant
D. the dental lab tech

C. the dental assistant

Which of the following is not a classification of dental materials?
A. preventive
B. biological
C. restorative
D. therapeutic

B. biological

The best resource for choosing which dental material to use could be determined by:
A. reading professional journals
B. meeting with manufacturers representatives
C. discussing which materials colleagues use
D. all of the above are good resources

D. all of the above are good resources

The first acceptable amalgam formula was developed by ________ in 1895.
A. Pierre Fuchard
B. Dr. Frederick Mckay
C. Dr. William Taggart
D. G.V Black

D. G.V Black

Today's approach to dental care is referred to as:
A. comprehensive care
B. evidence- based dentistry
C. individualized care
D. science- based dentistry

B. evidence-based dentistry

Evidence-based dentistry helps the clinician make decisions on what is relevant to incorporate into practice.
T/F

True

Who is considered the father of modern dentistry?

Pierre Fuchard

Which type of denture did George Washington wear?

Spring closed denture

What is the ADA designed for?

To help consumers make informed decisions about the safety and efficiency of products

In history, the earliest recorded mention of restorative dentistry occurs about:
A. 2500 BC
B. 600 BC
C. 1200 AD
D. 1700 AD

B. 600 BC

The earliest historical mention of the use of fluoride dates back to 1874 in:
A. england
B. colorado springs
C. prussia
D. china

A. england

Food and Drug Administration -

regulation over dental devices

American Dental Association

Seal of Acceptance

International standards organization

Standards to develop specifications on an international level

What would be the 4 characteristics of the perfect dental material?

biocompatible, exhibit long term clinical durability, be esthetically acceptable, and have low solubility

Silane coupling agent-

A chemical that helps bind the filler particles to the organic matrix

Alginate impression materials can have
A. color changing properties as the material sets
B. fast or regular set
C. hand or mechanical mixing
D. color and taste added
E. all of the above

E. all of the above

Positive bubbles on the surface of a stone cast were probably caused by:
A. improper pouring of the impression
B. the alginate mix being too thing
C. not rubbing alginate impression material on the occlusal surfaces of the teeth
D. the alginate mix being too thick

C. not rubbing alginate impression material on the occlusal surfaces of the teeth

Negative bubbles (holes) in the stone caste were probably caused by:

improper pouring of the impression

Alternative materials for alginate are usually:
A. polyether
B. vinyl polysiloxane
C. reversible hydrocolloid
D. none of the above

Not sure*** (B)

Mixing alginate mechanically can produce an impression mix that:
A. sets slower
B. has less surface detail
C. is extremely smooth
D. is less expensive than hand mixing

C. is extremely smooth

When making alginate impressions, the following is true:
A. the maxillary impression should be made before the mandibular impression
B. the powder should be placed in the mixing bowl before the water
C. the mandibular impression should be made before the maxillary impression
D. the impression should be placed in the back of the mouth first

c. the mandibular impression should be made before the maxillary impression because it is easier for the patient and prevents gagging in the beginning. The lower is easier for the clinician/patient working together.

Alginate impressions should be made:
A. with the patient in a supine position
B. with cold water
C. before cleaning the tooth
D. with the patient in a sitting position
E. with warm water

D. with the patient in a sitting position

Washing the impression after taking it from the mouth:
A. removes all of the microorganisms
B. removes the majority of the debris
C. does not remove the mucous from the impression
D. is not always necessary

B. removes the majority of the debris

Before storing the impression, it should be:
A. dried thoroughly
B. allowed to remain in a paper towel moistered with water
C. placed in a very moist environment
D. placed in a sealable plastic bag with a few drops of water

D. placed in a sealable plastic bag with a few drops of water

When mixed with water, alginate impression materials have:
A. very good long term stability
B. poor long term stability
C. usefulness in only a few areas of dentistry
D. the ability to be toxic, if swallowed

B. pour long-term stability

The addition of filler particles makes the organic resin stronger and more wear resistant
True/False

True

Fillers may be modified with ions to improve their characteristics
True/ False

True

How can composites be classified?

by the size of the filler particles they contain

Define composite resin

tooth colored materials that are used in both the anterior and posterior parts of the mouth

What are composite resins mostly composed of, according to the book?

Mainly of an organic resin (polymer) matrix and inorganic (silica) filler particles joined together by a silane coupling agent that sticks the particles to the matrix

The most commonly used resin for the matrix of composites is called?

bis- GMA, produced by reacting glycidal methacrylate with bisphenol-A.

In order to reduce viscosity and allow loading with filler particles, what is then used?

a low molecular weight monomer, TEGDMA, is added.

What are monomers?

double carbon bonds that are linked together to form a resin or polymer

What is a coupling agent used for?

to provide a stronger bond between the organic fillers and the resin matrix

What do manufactureres recommend doing with resin?

refrigerate the material. the average shelf life, if stored, is 2-3 years

How are light cured composites supplied?

in compules or syringes

_____ ______ _______ are low viscosity resins that flow well into the microscopic porosities and irregularities of the etched surfaces

enamel bonding agents

Etching of enamel creates a _____ ____, low tension surface that makes the surface easier to wet.

high energy

Contaminants on the surface, such as saliva or blood, can dramatically lower the strength of the bond to the enamel
True/False

True

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