Answer The Following Dental Materials Midterms Of 2020 Quiz

1. What are the ingredients of Alginate (Aqueous elastomeric impression material like Agar)?

Hydrocolloids and Silica

Water and Sodium alginate

Calcium sulfate and Potassium alginate

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Alginate is a water-based elastomeric impression material composed of sodium alginate and water. Sodium alginate forms a gel when combined with water, making it suitable for dental impressions.

Explanation

Alginate is a water-based elastomeric impression material composed of sodium alginate and water. Sodium alginate forms a gel when combined with water, making it suitable for dental impressions.

2. What are the advantages and disadvantages of Alginate?

Pros:easily "wets" tooth structure due to H2O (hydrophilic)easy to "pour" in gypsum materialCons:irreversible hydrocolloidH2O evaporates fastimpression shrinks - loss of accuracy (pour soon after disinfection)Syneresis - H2O lossImbibition - H2o absorption

Pros: difficult to work with, does not accurately capture tooth structure. Cons: easily reversible hydrocolloid, slow H2O absorption.

Pros: high strength and durability, suitable for long-term storage. Cons: poor compatibility with gypsum materials, difficult to remove from tray.

Pros: excellent accuracy in capturing tooth structure, stable impression over time. Cons: expensive material, limited shelf life.

The correct answer outlines the advantages and disadvantages of Alginate, including its ability to 'wet' tooth structure and be easily poured in gypsum material, as well as drawbacks such as irreversible hydrocolloid and loss of accuracy due to shrinking. The three incorrect answers provide contrasting information which does not align with the characteristics of Alginate.

Explanation

The correct answer outlines the advantages and disadvantages of Alginate, including its ability to 'wet' tooth structure and be easily poured in gypsum material, as well as drawbacks such as irreversible hydrocolloid and loss of accuracy due to shrinking. The three incorrect answers provide contrasting information which does not align with the characteristics of Alginate.

3. What are the primary types of electron bonds?

?Ionic bonds simple chemical bonds resulting from mutual attraction between + and - chargesan atom gives up one of its E- which is accepted by another atom in short supply (ex. NaCl)

Covalent bonds are formed when atoms share a pair of electrons to achieve a full outer shell.

Van der Waals bonds result from temporary polarization of atoms or molecules, creating weak attractions.

Metallic bonds occur between metal atoms where electrons are delocalized and move freely throughout the structure.

4. What type of bonds involve 2 valence electrons being shared and tend to be strong?

Hydrogen bonds

Ionic bonds

Metallic bonds

Covalent bonds 2 valence electrons are sharedtend to be strong (ex. H20)

Covalent bonds involve the sharing of electrons between atoms, resulting in a strong bond. Ionic bonds involve the transfer of electrons, metallic bonds involve a sea of electrons shared between atoms, and hydrogen bonds are relatively weaker interactions between a hydrogen atom and an electronegative atom.

Explanation

Covalent bonds involve the sharing of electrons between atoms, resulting in a strong bond. Ionic bonds involve the transfer of electrons, metallic bonds involve a sea of electrons shared between atoms, and hydrogen bonds are relatively weaker interactions between a hydrogen atom and an electronegative atom.

5. What are metallic bonds?

Forces of attraction between free-floating valence e- and neutral metal cat-ions.

Forces of repulsion between free-floating valence e- and positively charged metal cat-ions.

Forces of attraction between free-floating valence e- and negatively charged metal cat-ions.

Metallic bondsforces of attraction between free-floating valence e- and positively charged metal cat-ionseasily identifiablesimilar to covalent bonds in that they also share valence e- between atoms

Metallic bonds are formed between positive metal ions and delocalized electrons, leading to a sea of electrons within the structure. This allows for electrical conductivity and unique properties seen in metals.

Explanation

Metallic bonds are formed between positive metal ions and delocalized electrons, leading to a sea of electrons within the structure. This allows for electrical conductivity and unique properties seen in metals.

6. What are secondary bonds also known as?

Aka van der Waals forcestend to be weaker than primary bondsconsidered to be more physical than chemical (DO NOT share e-)Van der Waals forces are due to the formation of a dipole, can be fluctuating or permanent

Ionic bonds

Covalent bonds

Metallic bonds

Secondary bonds, also known as Van der Waals forces, are weaker than primary bonds and are considered to be more physical than chemical interactions. These forces are due to the formation of a dipole, which can be fluctuating or permanent.

Explanation

Secondary bonds, also known as Van der Waals forces, are weaker than primary bonds and are considered to be more physical than chemical interactions. These forces are due to the formation of a dipole, which can be fluctuating or permanent.

7. Which types of bonds are present in ceramics, metals, and molecular solids (polymers)?

Covalent bond - ceramics, Ionic bond - metals, Secondary bond - molecular solids (polymers)

Ionic bond - ceramics, Covalent bond - metals, Metallic bond - molecular solids (polymers)

Metallic bond - ceramics, Ionic bond - metals, Covalent bond - molecular solids (polymers)

Ceramics - ionic bondMetals - metallic bondMolecular solids (polymers) - covalent & secondary bonds

Ceramics are primarily held together by ionic bonds, metals by metallic bonds, and molecular solids (polymers) by a combination of covalent and secondary bonds.

Explanation

Ceramics are primarily held together by ionic bonds, metals by metallic bonds, and molecular solids (polymers) by a combination of covalent and secondary bonds.

8. What is cross-linking?

A type of exercise routine that combines various forms of cardiovascular and strength training.

The process of linking two separate documents together using hyperlinks.

The genetic crossing of two different species resulting in a hybrid offspring.

The linking of one coil (or polymer chain) across to another with wire (or a covalent bond)ex. rubber band: more cross-linking = stiffer

Cross-linking refers to the linking of one coil or polymer chain to another via wire or covalent bond, resulting in increased stiffness.

Explanation

Cross-linking refers to the linking of one coil or polymer chain to another via wire or covalent bond, resulting in increased stiffness.

9. What is the process of polymerization?

Free radicals, that add together (double bond)

Oxidation of polymer chains

Sublimation of polymer molecules

Hydrolysis of monomers

Polymerization is a process where monomers join together to form long chains. The correct answer refers to free radicals adding to double bonds, which is a common method of polymerization. The incorrect answers do not accurately describe the process of polymerization.

Explanation

Polymerization is a process where monomers join together to form long chains. The correct answer refers to free radicals adding to double bonds, which is a common method of polymerization. The incorrect answers do not accurately describe the process of polymerization.

10. What does the term 'linear coefficient' refer to?

The rate at which a line increases or decreases.

A mathematical term representing the slope of a line.

Coefficient of thermal expansion?Measure of the change in volume in relation to the change in temperature

None of the above

A constant value in a linear equation.

The linear coefficient specifically refers to the coefficient of thermal expansion, which measures how a material's volume changes in response to temperature variations. This term is distinct from other mathematical interpretations of 'coefficient,' as it pertains to thermal properties.

Explanation

The linear coefficient specifically refers to the coefficient of thermal expansion, which measures how a material's volume changes in response to temperature variations. This term is distinct from other mathematical interpretations of 'coefficient,' as it pertains to thermal properties.

11. What is the relationship between modulus of elasticity, stress, and strain?

Characteristics of a material and its atomic bondsHigh modulus of elasticity = stiff material

Modulus of elasticity is solely dependent on the material's density.

Modulus of elasticity is the same as the tensile strength of a material.

Modulus of elasticity is equal to the temperature at which a material deforms.

The modulus of elasticity is a measure of a material's stiffness, which is determined by the characteristics of the material and its atomic bonds. A higher modulus of elasticity indicates a stiffer material.

Explanation

The modulus of elasticity is a measure of a material's stiffness, which is determined by the characteristics of the material and its atomic bonds. A higher modulus of elasticity indicates a stiffer material.

12. What is the capital of France?

Berlin

Rome

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London

Paris is the capital city of France and is known for its cultural landmarks, fashion, and cuisine.

Explanation

Paris is the capital city of France and is known for its cultural landmarks, fashion, and cuisine.

13. Yield strength.

Ultimate strength

Fracture point

"elastic limit" or "proportional limit"the point on the stress-strain plot at which the line starts to curve and plastic deformation (not returning to original shape) begins

Tensile strength

Yield strength is the point on the stress-strain curve where plastic deformation begins, while ultimate strength refers to the maximum stress a material can withstand before failure. Tensile strength is the maximum stress a material can withstand while being pulled before breaking. The fracture point is where the material breaks completely.

Explanation

Yield strength is the point on the stress-strain curve where plastic deformation begins, while ultimate strength refers to the maximum stress a material can withstand before failure. Tensile strength is the maximum stress a material can withstand while being pulled before breaking. The fracture point is where the material breaks completely.

14. What does the plastic deformation limit refer to?

Point where the material can still return to its original shape.

Point where the material breaks.

Point where the material shows temporary deformation.

Point where it is permanently stretched out

The plastic deformation limit is the point where the material undergoes permanent stretching or deformation without breaking.

Explanation

The plastic deformation limit is the point where the material undergoes permanent stretching or deformation without breaking.

15. Which materials are good thermal conductors?

Ceramics

Polymers

Metals = good conductorsPolymers, ceramics, porcelain = poor conductors(which is why we want porcelain over the metal)

Porcelain

Metals are known for their high thermal conductivity, making them ideal for conducting heat efficiently. Conversely, polymers, ceramics, and porcelain are poor thermal conductors, which is why they are not suitable for applications where heat conduction is required.

Explanation

Metals are known for their high thermal conductivity, making them ideal for conducting heat efficiently. Conversely, polymers, ceramics, and porcelain are poor thermal conductors, which is why they are not suitable for applications where heat conduction is required.

16. What are the types of stress in mechanics?

Expansion: pushing or crushing

Compression: pushing or crushingTension: pulling Shear: slipping/sliding by on anotherTorsion: twistingBending: one side is compressed, other is stretched

Friction: slipping/sliding on another

Torque: pulling

In mechanics, stress is broadly categorized into compression, tension, shear, torsion, and bending. Each type of stress exerts different forces on objects based on their applications.

Explanation

In mechanics, stress is broadly categorized into compression, tension, shear, torsion, and bending. Each type of stress exerts different forces on objects based on their applications.

17. Which substance is commonly used as an adhesive in dentistry?

Super Glue

Epoxy

ORTHOPHOSPHORIC ACID 37% (acid to etch enamel "etchant", most commonly used today)micromechanical

Hot Glue

In dentistry, ORTHOPHOSPHORIC ACID 37% is commonly used as an adhesive due to its ability to etch enamel and provide micromechanical retention for dental restorations.

Explanation

In dentistry, ORTHOPHOSPHORIC ACID 37% is commonly used as an adhesive due to its ability to etch enamel and provide micromechanical retention for dental restorations.

18. What is the purpose of enamel etching?

Etching removes enamel from the tooth surface.

Etching increases the viscosity of adhesive for better flow.

Etching allows LOW viscosity adhesive to flow into irregularities and pits/fissures

Etching is used to smooth out the enamel surface.

Enamel etching is a dental procedure that involves using an acidic solution to create surface irregularities on the enamel, allowing low viscosity adhesive to flow into these irregularities for better adhesion. This process does not involve removal of enamel, it does not increase the viscosity of adhesive, nor does it aim to smooth out the enamel surface.

Explanation

Enamel etching is a dental procedure that involves using an acidic solution to create surface irregularities on the enamel, allowing low viscosity adhesive to flow into these irregularities for better adhesion. This process does not involve removal of enamel, it does not increase the viscosity of adhesive, nor does it aim to smooth out the enamel surface.

19. Which dental material is commonly used for dentin bonding?

Composite resin

Zinc phosphate cement

Polycarboxylate cement, then glass ionomer cements. (b/c dentinal bonding incorporates acid etching, think of it as an extension of the acid etching process rather than replacement)

Resin-modified glass ionomer cement

Dentinal bonding typically involves the use of polycarboxylate cement followed by glass ionomer cements due to their compatibility with the acid etching process used for bonding.

Explanation

Dentinal bonding typically involves the use of polycarboxylate cement followed by glass ionomer cements due to their compatibility with the acid etching process used for bonding.