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Why is it necessary to study the science of dental materials
Help us to explain The properties and performance of material, examine the internal structures of the dental materials, atomic makeup of matter allows us to predict the properties
States of matter
Solid, liquid,gas,colliod
Atomic bonds
Are cohesive forces, are the bindings forces that holds atoms together, are the results of electromagnetic forces
Are rigid and dence, have low vapor pressure, have low energy state, resist external forces, has the strongest atomic bond, is characterized by a space lattice
Space lattice
Most common form is a cubic, in the shape of all solids
interatomical distance
Atoms in a space lattice maintaining their position relative to 1 another
Normal interatomic distance
The distance at which the force of attraction between atoms equals the force needed to repel them
Cubic shape of space lattice can be either _____ _____ _____ or they can be in ____ range _____
Short range order, long, order
2 types of solids
Chrystalline and amorphous
Short range order
Consistent range only 5 to 10 neighbors apart
Long range order
3 d spatial relationships of repeated atoms and molecules are millions of thousands of neighbors apart but the distance is consistent
Have short range order, energy level is high, has a stronger attraction between molecules than gases but not as strong as solids, are unable to carry a load or maintain a shape without support
Molecular relationship of water
Molecules are 5 to 10 neighbors apart
Atomic bonds are week, has no molecular organization, and will take on any 3 d shape of any container, if thermal energy is removed by cooling it will condense into liquid, has no given volume, has highest energy level
Is a mixture of gases, liquid, and solids
Types of bonds
Primary bonds, secondary bond
Primary bonds
Are strong bonds between atoms that involve the transfer or sharing of electrons between atoms
Valence electrons
Electrons involved in chemical reactions and atomic bonds
Ionic bond
Occurs when 1 atom donates its electrons to another, And both become stable through linkage
Ionic bond occurs when there is ___________ between a _______ and ________ charge
Interaction, positive, negative
Ionic bonds are not as strong as _________ _____
Covalent bonds
Examples of ionic bonds
Sodium chloride, table salt, porcelain
Covalent bond
Are strong and stable, is the result of sharing of electrons between 2 atoms, is very directional
Has sharp and definite melting or freezing points, Are both long and short range order, Resist forces, Most used in dentistry are the cubic type space lattice
Examples of christallines
Salt, diamonds, hydroxyapatite of teeth, gold, silver alloy
Is without form, has no definite space lattice, has short range order, molecules tend to be distributed random, does not have a definite melting or freezing point, has closer 3 d relationship
Few materials are bonded only by ________ _____, usually a combination of ________ and _________ _____
Covalent bonds, covalent and hydrogen bonds
Metallic bonds
Occurs when many atoms share all of their outer valence electronics with their neighbors, arrangement is very strong and stable, makeup is dense and heavy
Secondary bonds
Are partial charges the result from an uneven distribution of electrons around an atom or molecule, are weaker and less stable
Metallic bonds are ____ __________ of ____ and ___________
Good conductors, Heat, electricity
_________ charges of secondary bonds can be _________ or _________, ____ or ______
Partial, temporary, permanent, weak, strong
________ _____ are responsible for the limited strength in polymers, and has ________ ________ _____ of ______ and individual ______ of ________ _____
Secondary bonds, Internal covalent bonds, carbon, chains of hydrogen bonds
Hydrogen bonds
Are special type of permanent dipole, contains only 1 electron although weak, is the strongest all secondary bonds
Hydrogen bonds are important in ______ ________ and in ___ and ________
Dental Polymers, dna, protein
Atomic bonds as they relate to dental materials
Metals, ceramics, polymers, composite
Why is colloid not a true solution?
Because 1 material will not disolve into another
Examples of colloid
Fluoride foam, alginate, reversible hydrocolloid
An _____ _________occurs between a _____ ________ and a cement and a _____ structure
Ionic interaction, glass ionomer, tooth
Examples of covalent bonds
Carbon-carbon bond that holds the polymer chain of dental composites and dentures, Protein, DNA
All metals in dentistry consist of _________ _____
Metallic bonds
Metals are:
Opaque in nature, have luster, and electrical conductivity
Ceramics are:
Bonded with ionic bonds, are strong when compressed
Consent of repeating units of long chains of covalent bonds, and weaker individual hydrogen bonds, has high molecular weight compound, are poor conductors of heat
Variety of bonds between the polymer chain that help to determine its strength
Cross linking, linear polymers, and permanent dipole
Polymers with permanent dipoles
Have a side group with an uneven distribution of elect,,ron
With permanent dipoles, as the ______ and intensity of the charges _________ so does the _______ and _________
Number, increases, strength, stiffness
Example of polymer with permanent dipoles
PFI and yellow tip probe
Linear polymers
Contains a fluctuating dipoles, which is a weak bond that is broken easily as the chains slide by one another at room temperature, are processed by heat, has a secondary bond
Examples of linear polymer
Plastic bags, bleaching trays, bite guards
Cross linking polymers
Are linked by covalently bonded atoms, preventing them from sliding past on another
Cross-linking results in a _____ somewhat ________ _______ that can sometimes be ________, according to the amount of ____ _____ that exist
Stiff, stronger material, stretched, cross links