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WorksheetsDentistry materials revisions
Total questions: 106
Worksheet time: 54mins
What kind of forces occur at the interface between the tooth and the crown?
Select one or more:
torsion
shear
compression
tangential
tensile
A metal is considered to have a high density when it is...
> 10 g/cm3
> 1 g/cm3
> 3 g/cm3
> 5 g/cm3
Of the following statements which is false
Both in plastic and elastic deformation, the material returns to its original state and shape
The final resistance is when the material stops deforming due to its fracture
Elastic deformation means that when the force that effects said deformation ceases, the material returns to its original state and shape
Plastic deformation means that when the force that effects said deformation ceases, the material is permanently deformed
The clinical applications of fusibility in dentistry are:
lost wax technique and injection.
wax up and welding.
wax up and injection.
lost wax technique and welding.
Can hardness values always be related to the ability of a material to wear resistance?
True
False
Which impression materials provide the best reproduction of details?
does not depend on the viscosity and flowability of materials.
low viscosity and heavy materials.
high viscosity and high flowability materials.
low viscosity and fluid materials.
What is the role of surfactants in impression materials?
cause hydrophobic materials to become hydrophilic.
hydrophobic materials do not reproduce the details.
cause hydrophilic materials to become hydrophobic.
hydrophilic materials do not reproduce the details.
What are the factors that determine each impression material has its own working time?
mixing type, moisture, setting reaction and time.
temperature, mixing type, setting reaction and material viscosity.
temperature, moisture, mixing type and material viscosity.
temperature, moisture, setting reaction and time.
The clinically acceptable setting time of an impression material is:
about 5 minutes.
about 3 minutes.
about 1 minute.
about 8 minutes.
Which is the minimum time in advance for the preparation of a customized tray?
1 hour.
24 hours.
3 hours.
48 hours.
What is the function of diatomaceous earth in alginate composition?
it hardens the plaster when it is poured on alginate.
it affects physical properties and setting time.
it increases resistance and strength of material.
it accelerates the alginate setting reaction.
During the gypsum setting reaction, when is the exothermic reaction and heat release perceived?
hardening phase.
final fluid phase.
fluid initial phase.
plastic phase.
What type of gypsum is obtained by wet calcination in a calcium chloride solution?
type III and V.
type II and IV.
type III and IV.
type IV and V.
type I and II.
Why is important to maintain a correct water/powder ratio in gypsum?
Select one or more:
it affects the tear strength of the material.
the type of expansion (normal or hygroscopic) depends on the W/P ratio.
specifies the physical and mechanical properties of the material.
an excess of water makes the material more brittle.
indicates the minimum amount of water required for mixing the material.
As the dimensional stability of alginate is low, we must:
Select one or more:
delaying as long as possible pouring the impression.
keep the impression as dry as possible.
we must remove it in a single, quick movement.
the impression must be poured within one hour.
keep the impression moist until it can be poured
Does cold water increase or decrease the working and setting time of alginate?
Increase
Decrease
Clinically, what are the mechanisms for reducing the gypsum's setting speed during mixing its components?
increase both amount of water and mixing time.
increase amount of water and decrease mixing time.
decrease both amount of water and mixing time.
decrease amount of water and increase mixing time.
What is the accuracy level of alginate as an impression material?
low accuracy
medium accuracy
high accuracy
What is the permanent deformation rate of alginate?
1
3
5
7
What carbon concentration must the stainless steel burs have?
from 1 to 2% carbon.
from 0.6 to 3% carbon.
from 0.5 to 3% carbon.
from 0.8 to 2% carbon.
What can be the most serious complication when working with an air-high speed instrument (turbine)?
cause a temperature rise to tooth and its pulp chamber.
the mismatching of the bur and that it comes out.
cause iatrogenic injury.
cause subcutaneous emphysema.
Why is essential to use water to cool handpieces?
to have a better visibility of the working area.
to prevent heat increase in rotary instruments (handpieces and bur) and in tooth.
to prevent the handpieces and burs being damaged.
to avoid damaging tooth.
What is the Vickers hardness of tungsten carbide burs?
1650-1700 VHK.
1700-2000 VHK.
800-1000 VHK.
650-800 VHK.
1000-1200 VHK.
What are the differences between high-speed high-torque and high-speed low-torque instruments?
Select one or more:
power
high-torque instruments stall at additional pressure.
weight
rotational speed.
low-torque instruments stall at additional pressure.
What is the temperature increase that is considered critical for both tooth and instrument?
3-6ºC.
6-10ºC.
5-8ºC.
20ºC.
Which elastomers can be poured multiple times?
polyether and addition silicones.
polysulphides and addition silicones.
condensation silicones and polyether.
condensation silicones and polysulphides.
The elastic recovery of polysulphide is:
the same as condensation silicones.
the same as alginate.
slightly lower than polyether.
does not recovery elastically, but rather shrinks.
Which of the following answers is correct:
all are true.
the polymerisation reaction of polysulphides is an addition reaction.
silicones can have either a condensation or an addition reaction depending on the type.
the polymerisation reaction of polyether is a condensation reaction.
Which of the following materials is not part of the group of elastomers:
Reversible hydrocolloids
Polyethers
Polysulphide
Condensation silicones
The polymerisation reaction of polyether is:
Condensation.
Addition.
It is the same as alginates.
Activated by light.
Type of setting reaction of zinc oxide-eugenol impression material:
addition
thermopolymerizable.
condensation
acid base
What are the basic components for the setting reaction of zinc oxide-eugenol
Zinc oxide and magnesium chloride
Eugenol and hydrogenated resin
Zinc oxide and eugenol
Magnesium chloride and eugenol
Which of the following is correct concerning zinc oxide-eugenol impression material?
It can permanently stain clothes
If there are retentions in the tissues, it could fracture
Has adhesion to other impression components.
They are all true
Which of the following answers is correct about zinc oxide-eugenol impression material:
Is an inelastic impression material.
Is a material used to take implant impressions.
all are true.
Is a material used to take impressions of teeth.
Acrylic resins are indicated in the following cases, except... ?
Complete mucosa-supported prothesis
Definitive fixed prothesis
Removable orthodontic plates
Occlusal guards
Which acrylic resin can be repaired with flowable composites?
Bis-acrylic resin
PolyMethy-methacrylate
PolyEthyl-methacrylate
All of them
Which acrylic resin has the best colour stability?
PEMA
Light-curing resins
Bis-acrylic resins
Heat-curing resins
In acrylic materials with soft relining, what is the chemical element that produces plasticity and gives this soft consistency to the relining material?
Phthalates or esters of phthalic acid
Benzoyl peroxide
Ethylene glycol dimethacrylate
The tertiary amine
In what step of the handling of acrylic resins the liquid begins partially dissolve the powder?
Plastic phase
Sandy phase
Adhesive phase
Polishing phase
Polymerization phase
As a component of acrylic resins, hydroquinone's function is:
Inhibitor
Activator
Iniciator
Plasticizer
As a component of acrylic resins, Dimethyl-p-toluidine's function is:
Inhibitor
Activator
Initiator
Cross-linking agent
As a component of acrylic resins, ethylene glycol dimethacrylate's function is:
Inibitor
Activator
Initiator
Cross-linking agent
As a component of acrylic resins, dibutyl phtahlate's function is:
Inhibitor
Activator
Plasticizer
Iniciator
As a component of acrylic resins, Benzoyl peroxide's function is:
Inhibitor
Activator
Plasticizer
Iniciator
Concerning acrylic resins, which of the following answers regarding polymethacrylates is true:
Poly-methylmethacrylate has a lower glass transformation temperature than poly-butylmethacrylate
As the organic acid chain lengthens in polymethacrylates, the glass transformation temperature decrease
Poly-propylmethacrylate has a higher glass transformation temperature than poly-ethylmethacrylate
All are true
Which acrylic resin has the best wear resistance?
PEMA
CAD/CAM materials
Bis-acrylic resin
Heat-curing resin
Which of the following answers is correct:
The addition polymerisation reaction release water as by-product
The condensation polymerisation reaction releases a by-product
Any polymerisation reaction, neither addition nor condensation, releases a by-product
In any addition or condensation polymerisation reaction, there is a release of water as a by-product
What are the most important drawbacks of polymers?
The polymerisation shrinkage and the exothermic reaction
The exothermic reaction and the release of by-products
The exothermic reaction and the expansion within the polymerisation reaction
The polymerisation shrinkage and the release of by-products
What is the role of stabilizers in the polymer composition?
Delay polymerization once the chemical reaction has started
Maintain physical and chemical properties for long periods of time
Improve some material properties
Avoid spontaneous polymerization of the components
What is the clinical application of rigid addition polymers?
Resin-based composites
Pit and fissure sealents
Acrylic resins
Dental adhesives
The completion of the polymerization reaction is made by:
Termination by hydrogen transfer
All are correct
Termination by direct chain coupling
Spatial cross-linked chains
Termination by chain transfer
What type of polymer are waxes?
Easily deformable thermoplastic linear polymers
Rigid thermosetting cross-linked polymers, that are easily deformable
Rigid thermoplastic branched polymers
Easily deformable thermosetting linear polymers
Thermosetting branched polymers, that are easily deformable
Why is it important for impression materials to have a low glass transition temperature?
Because they are easy to handle at oral temperature
Because they are rigid in the oral environment
Because they are flexible in the oral environment
Because they change their state at oral temperature
What is the minimum power required for dental curing lights?
250 mW / cm2
350 mW / cm2
450 mW / cm2
400 mW / cm2
PAC light-curing units allow composites to be cured in a shorter time than typical QTH lights or LED lights without adversely affecting properties.
True
False
What is the wavelengh range in which current LED light curing-units work?
380-490nm
380-540nm
400-515nm
450-500nm
How long does it require to polymerize dark composites?
Between 30 and 40 seconds
Between 20 and 30 seconds
Between 5 and 10 seconds
Between 10 and 20 seconds
Photoinitiators are present in the organic matric of composites
0.2% by weight
0.5% by weight
1% by weight
2% by weight
What happens to the composite if it polymerizes from the dirst moment with a high power?
Superficial polymerization and abrupt shrinkage of composite
Abrupt shrinkage and full polymerization of composite
Superficial polymerization and high degree conversion of composite
Abrupt shrinkage andhigh degree conversion of composite
What is the function of phenylpropandione?
Bonding agent between polymer chains
Photoinitiator in composites of light tones
Stabilizer of the composites polymerization reaction
Activator of the polymerization reaction
What is the recommended composite thickness for correct polymerisation?
About 2mm
About 3mm
About 1mm
About 4mm
What is the light absorption range of camphorquinones?
480 to 550 nm
450 to 490 nm
450 to 550 nm
400 to 490 nm
What is the main characteristic of univversal adhesives?
Recommanded for use as etch and rinse adhesive on dentine only
Can be used both as etch and rinse adhesives and as self-etch adhesives, both in enamel and dentine
Can only be used as self-etch adhesive
Can only be used as etch and rinse adhesive
The acid etching time of the tooth surface is as follows:
Enamel 30" and dentine 15"
Enamel 10" and dentine 20"
Enamel 30" and dentine 20"
Enamel and dentine 20"
Regarding the adhesion of the different dental structures, which of the statements is true ?
Micro-mechanical adhesion is the basis of adhesion in dental enamel
All answers are true
Acid etching produces micro-roughness in enamel
Hybrid bonding is the basis for bonding to dentin
Which of the following statements regardin dental bonding is true ?
The micro-mechanical retention produced by acid etching is fundamentally effective in dentin
The principles of physical and chemical adhesion are the basis of dental adhesion in dentistry
The smear layer is the residue of enamel and dentin that remain on the suface after cutting the tooth with the bur or other systems and reduce the permeability of the tubules
Hybrid adhesion is essential in enamel
Which of the following metals are considered biodegradable?
Chromium and cobalt
Copper and silver
Gold and palladium
Magnesium and zinc
What are the three ways to crystallize metals for dentistry?
Cubic to face centered, cubic to body centered and hexagonal
Simple cubic, rhombohedral and simple tetragonal
Cubic to face centered, hexagonal and rhombohedral
Simple cubic, cubic to face centered and rhombohedral
What grade of titanium is an alloy?
II
III
V
I
IV
Which of the following titanium grades has the highest elongation rate?
I
II
IV
V
III
What is the reason they try to limit the prosthesis metals in the mouth?
Due to possible allergies to metals
All are true
Due to the dark color they can give to the restorations
Due to possible corrosion phenomena
What do UDMA, bis-EMA, and oxirane-siloxane monomers have in common compared to Bis-GMA?
They are less aesthetics
Their failure rate is higher
They have less polymerization shrinkage
They absorb less water
Which of the following polymer systems is used for the organic matric in composites?
Triethylene glycol dimethacrylate (TEGDMA)
Poly(methyl methacrylate)
Polystyrene
Bisphenol A-glycidil methacrylate (Bis-GMA)
Urethane methacrylate (UDMA)
Which of the following organic monomers have an ionic polymerization reaction?
Bis-EMA
TEGDMA
Oxirane-siloxane
UDMA
Why can improper polymerization of composites cause pulp irritation?
Because unreacted monomers are left behind and can leak into the pulp chamber
Due to recurrent decay
For the toxicity of unreacted photoinitiators
By the microleakage caused in the restoration
What are the clinical drawbacks of polymerization shrinkage of composites?
Postoperative sensitiviy, debonding and recurrent decay
Microleakage, postoperative sensitivity and recurrent decay
Water sorption, debonding and microleakage
Microleakage, water sorption and recurrent decay
What is the function of silane in the composite composition?
It is the cross-linking agent that finishes the reaction
It is the coupling agent of the organic and the inorganic components of composite
It is the catalyst that makes the polymerization reaction go faster
It is part of the inorganic composition and has no specific function
Which of the following statements regarding ceramics is false?
High-strengh feldspathic ceramics reinforced with leucite crystals lose translucency
Feldspathic ceramics have a low fracture strengh around 56 MPa
The main indication of lithium-reinforced feldspathic ceramics is the reinforcement core
Leucite reduces the porosity of feldspathic ceramics
The indications of the ceramics considered low fusion are:
Total ceramic crowns
Metal ceramic crowns and bridges
Removable prosthesis teeth
Ceramics on titanium and corrections
What is a disadvantage of metal-ceramic crowns?
They have a low fracture resistance
They have a low translucency
They are very brittle
The ceramic on the metal degrades faster
Which of the following statements is correct for oxide ceramics?
All are true
They are very aesthetic
Its main indication is as reinforcement cores or copings
All of them have a high part of the vitreous phase
Silicate ceramics can be:
Zirconia
Aluminium
Infiltrated with glass
Feldspathic
Zirconia ceramics are
Ceramics infiltrated with glass
Polycrystalline ceramics
Leucite-reinforced ceramics
Lithium-reinforced ceramics
Which of the following options is an advantage of CAD/CAM ceramics?
Can only be used with one type of ceramic
It wear out faster
The price is higher than conventional ceramics
Shortens working time
Which of the following materials is not used as a cavity liner or pulp capping?
Glass ionomer
Compomer
Theracal
Biodentine
What effect does temporary zinc oxide-eugenol cement have on permanent resin luting agents?
Inhibits the polymerization of resin luting agents
Has no effect on resin luting agents
Increases the polymerization of resin luting agents
Increases the retention of resin luting agents
The intermediate-use temporary filling materials are characterised by:
Caries prevention
Easy placing and remotion
They had hygroscopic expansion and a good sealing
High resistance to wear
Why do resin luting agents generate less postoperative sensitivity?
They have an exclusive chemical bond with the tooth
They only produce mechanical retention and have less water sorption
They produce a good marginal sealing and seal dentinal tubules
They maintain the smear layer that acts as an insulator
Which of the following cements is not only acid-base setting
Zinc oxide-eugenol cement
Calcium hydroxide cement
Silicate cement
Compomer cement
Which of the following statements is false regarding glass ionomer cements?
It does not have adhesion with dental tissues
It is easy to mix
It has anticariogenic effect
It has high tensile strengh
What does the layer/film thickness of the cements indicates?
Indicates the amount of cement that flows when a crown is placed
Indicates the space occupied by cement
Indicates the retention of the cement related to the crown
Indicates the viscosity of the cement during setting
What test is used to identify wether a person has a colour-related visual impairment?
Wataha test
Shen test
Kawasaki test
Ishihara test
Which of the following statements is false regarding tooth shade?
The incisal area of the tooth is more translucent
The canines are the most saturated teeth in concentration of tone
The color of the tooth is basically provided by the enamel
The cervical area of the tooth is more opaque
Which of the following statements regarding the phenomena of light is false?
Refraction is the deviation in the direction of a light wave when changing from one medium to another with different dentisty
>Translucency is when an object lets part of the light pass through and reflects a part
Diffusion is the deviation of any light ray when it hits a surface
Refraction can be specular of diffuse
In the opalescence of teeth the same in children, adults and the elderly?
True
False
From the following statements, which one is correct?
Tetrachromatism in humans makes the range of visible colors more sensitive
Color blindness is more common in women than men
Tetrachromatism in humans allows us to see beyond the visible spectrum
They are all false
What are the three colour dimensions described by Munsell?
Hue, value and chroma
Saturation, intensity and value
L, a, b
Tone, tint and lightness
What kind of light in Kelvin degrees would be indicated to take the color of the teeth in the mouth?
5500 to 5600°K
4500 to 4600°K
3500 to 3600°K
6500 to 6600°K
What are the most allergenic metals in dentistry?
Boron, iron, copper, chromium and cobalt
Nickel, palladium, boron, strontium and tin
Nickel, palladium, chromium, cobalt and tin
Aluminium, titanium, copper, tin and palladium
What is a disadvantage of polishing composites and acrylic resins?
Polishing does not cause any inconvenience
The risk of contact allergies to released particles
The risk of particle inhalation
Increased allergic reactions and candidiasis in patients
What are the biocompatibility problems of metallic materials used in dentistry?
Allotropic material change and corrosion tendency
Corrosion tendency and probable allergy development
Probable allergy development and allotropic material change
The effects of changes caused by temperature and pH of the oral environment
What form of mercury can most affect the dentist and his team during treatment of an amalgam restoration removal?
Mercury steam
Oraganoleptic compounds
Liquid mercury
Intermetallic compounds
What is the monomer released by pit and fissure sealents and Bis-GMA composites when they are degraded?
Formaldehyde
Bis-phenol A (BPA)
TEGDMA
Glutaraldehyde
Which of the following answers is false regarding biocompatibility ?
It is not considered that any synthetic material is inert for people
All the answers are false
The greatest source of biocompatibility problems between living materials and tissues is at the interface between them
Once the material has been placed in the body, if it behaves in a biocompatible way, it will ne longer change over time and will always have this biocompatibility
What are dental materials that generate less biocompatibility problems?
Composites and dental ceramics
Metals and acrylic resins
Composites and metals
Glass-ionomers and dental ceramics
A medical device must be
safe
inert
safe and effective
effective
