Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
91 Cards in this Set
- Front
- Back
|
What is the definition of biocompatibility?
|
Biologically compatible by not producing a toxic, injurious, or immunological response in living tissue. Also, it is the ability to preform the appropriate host response.
|
|
|
What are three types of reactions?
|
toxic, allergic, irritant
|
|
|
What type of reaction is capable of causing cell or tissue death?
|
toxic
|
|
|
What type of reaction is capable of causing inflammation and irritation of tissue due to local immune response?
|
irritant
|
|
|
What type of reaction is due to hypersensitivity of a substance?
|
allergic
|
|
|
What is the difference between a local and a systemic reaction?
|
Local reactions occur in ADJACENT tissue (giggival, pulp, bone, mucosal tissue). Systemic reactions occur in REMOTE locations from site of contact.
|
|
|
How are systemic reactions usually presented?
|
They are usually presented as ALLERGIC skin reactions.
|
|
|
How can side effects be classified?
|
Side effects can be classified as acute or chronic. Chronic side effects are single or short term and it is usually reversible. Chronic side effects are multiple or long term (>3mo) and they are usually much harder to treat and are irreversible.
|
|
|
How do substances enter the body from a dental material?
|
1. Inhalation or swallowing (pass through GI or lungs)
2. absorption through soft tissue (skin, intraoral dermal tissue) 3. bloodstream (transport to remote organs) |
|
|
What is "bio-burden"?
|
"Bio-burden" is bacteria, other organisms, or organic debris that are brought into the oral cavity during placement or that accumulate at margins or under a material and cause LOCAL infection or toxicity.
|
|
|
What does sensitized mean?
|
Sensitized means to make hypersensitive or reactive to an antigen, especially by a second exposure or repeated exposure. It triggers an ALLERGIC reaction by being previously sensitized even if exposed to small amount. Cross-sensitivity can occur and reaction is usually immediate.
|
|
|
What does mutagenic mean?
|
causes genetic damage (genotoxicity)
|
|
|
What does carcinogenic mean?
|
causes tumor formation (cancer causing)
|
|
|
What does teratogenic mean?
|
causes malformation during embryonic development.
|
|
|
What is cytotoxicity?
|
to cause toxic effects at the cellular level WITHOUT necessarily resulting in death. Dosing is most important for assessing cytotoxicity.
|
|
|
What is the difference between delivered and exposure dose?
|
Delivered dose is the amount of chemical that is actually ABSORBED by the cell. Exposure dose is the amount of chemical APPLIED to the system.
|
|
|
What is the difference between repeatability and reproducibility?
|
Repeatability refers to being able to repeat an experiment multiple times in the SAME LAB. Reproducibility refers to being able to obtain the same results when experiment repeated in DIFFERENT LABS.
|
|
|
What does in vitro testing asses?
|
in vitro testing is testing done in a test tube and it asses cytotoxicity.
|
|
|
What does in vivo testing use and what does is asses?
|
in vivo testing uses animal models to asses more complicated biological interactions (neuro, endocrine)
|
|
|
Why do structures deliver blood to the hepatic portal veins?
|
Structures drain to the portal v. because they contain blood that needs to be filtered for toxins and nutrients.
The cranial mesenteric v. drains blood from the jejunum, ileum, duodenum, and pancreas. The caudal mesenteric v. drains blood from the cecum and colon. The gastroduodenal v. drains the pancreas, stomach, duodenum, and greater omentum. The splenic v. drains the spleen, stomach, pancreas and greater omentum. |
|
|
In vitro testing evaluates ____ dose, while in vivo testing evaluates _____ dose.
|
delivered, exposure
|
|
|
What are the advantages and disadvantages of in vivo studies?
|
Advantages:
- evaluates complex systemic interactions - response of subject is more comprehensive -more relevant to human response Disadvantage: -relevance to use of material can be questionable -legal/ethical issues -difficult to control test (stress) -difficult to interpret and quantify results. -expensive and time consuming |
|
|
What are the protocol factors for in vivo testing?
|
1. Size - smaller implants can be phagocytosed to elicit an inflammatory response, larger implants can lead to formation of multinucleated foreign body cells
2. Shape - form can elicit unfavorable response in animals but not humans 3. Sterility - very important to control to prevent bacterial colonization 4. Conditioning of Implant - 5. Containment of implant 6. Trauma - should be MINIMIZED, use slow speed with irrigation 7. Dose - affected by weight, surfae area, bulk size, # of implants, topography. |
|
|
What is necessary before human trials can begin?
|
multiple tests in vivo AND in vitro (animals) before human testing can begin. Can be very costly. ADA and FDA have a say in regulation of safety and efficacy of medical devices. ISO and ANSI design test protocols.
|
|
|
What methacrylates used for and what issues are associated with them?
|
-Methacrylates are used in almost all dental composites, binding agents, ect.
- mostly a problem for DENTAL PERSONNEL. usually causes contact dermatitis. |
|
|
What gloves have replaced latex gloves? Why?
|
Nitrile gloves have replaced latex gloves because many individuals show a severe allergic reaction on multiple exposures.
|
|
|
Allergy to what metal is seen more in females than in males? What other metal can illicit similar response?
|
Nickel allergies. Pd and other metals in the same periodic "family" can elicit the same response.
|
|
|
What component of Amalgam presents health concerns for dental personal and for the environment?
|
HG vapor exposure during placement can present health concerns for dental personnel. Amalgam waste can have environmental issues.
|
|
|
What issues are seen with exposure to dentin bonding agent that contain acidic agents for etching?
|
Can cause soft tissue irritation and pain but effects are usually transient.
|
|
|
What problems present from using peroxide containing bleaching agents?
|
Can be cytotoxic to vital teeth but sensitivity is usually transient.
|
|
|
What materials are highly biocompatible?
|
-Gold and high gold alloys (rare allergies),
-Ti, Ti alloys, Stainless steel, CoCr alloys ( passivating metal alloys) -Ceramic materials (porcelain, zirconia, alumina) |
|
|
What are the MOST biocompatible materials?
|
Ceramic materials (porcelain, zirconia, alumina)
|
|
|
What long range characteristics affect polymers?
|
molecular length, weight, conformation
|
|
|
What short range characteristics affect polymers?
|
chemical backbone, reactivity, side-group, xlinity
|
|
|
What is a copolymer? a homopolymer?
|
A polymer of many units of TWO different types. A hompolymer is many units of ONE type.
|
|
|
What are copolymers in these orders called?
1.@@#@##@#@ 2. @#@#@#@# 3. @@@@#### |
1. Random
2. Alternating 3. Block |
|
|
What is isomerism?
|
Isomerism are molecules with the same molecular formula but DIFFERENT structural formulas. (do not necessarily have similar properties)
|
|
|
what is a "mer"?
|
a "mer" means a part or a unit.
|
|
|
What is a macromolecule?
|
a macromolecule is an extremely long chaing of repeating units. ( = alginates, polypeptides, silicone polymers, metallic polymers, epoxies..)
|
|
|
What do the following stand for?
- AA - MA - PMA - MMA - PMMA |
AA- acrylic acid
MA- methyl acrylate PMA - polymethyl acrylate MMA - methyl methacrylate PMMA - polymethyl methacrylate |
|
|
Identify the structures:
1.Ch2=C-H-COOH 2.Ch2=C-H-COOCH3 3.Ch2=C-CH3-COOH 4.Ch2=C-CH3-COOCH3 |
1. Acrylic Acid (AA)
2. Methyl Acrylate (MA) 3. Methacrylic Acid (MAA) 4. Methyl methacrylate (MMA) |
|
|
What are the sources for polymers?
|
Before the source was rubber trees, not it is synthetic (H + C)
|
|
|
What are the classification for polymer textures?
|
-Resin- anything made out of plastic (liq or solid)
-Syrup -Elastomer - flexible plastiv materials (rubber tires, rubber bands, elastic imp materials) -Rosin - solid resin from nature (in tree roots, for violins and for baseball players) |
|
|
What are the 3 methods for polymerization?
|
- stepwise - piece by piece addition of multiple monomers
- chain - addition of single monomers to a growing chain - template - addition of monomers to preexisting template. (allows it to form how you want it, initiation with a catalyst) |
|
|
What are the two classifications of polymer by-products?
|
Addition- merunits + catalyst
Condensation - two merunits, NO CATALYST. merunits have affinity for each other. The byproduct is WATER and this allows the reaction to coninue |
|
|
What are the chain types of polymer classification?
|
- linear (MMA)
- branched - crosslinked - "volcanized" at high temperatures so they are stronger |
|
|
What are the types of chain configurations in polymers? How are the R groups arranged for each one?
|
Isotactic - R-groups on one side of the chain
Syndotactic- R-groups on alternating sides Atactic - R-groups everywhere |
|
|
What are the structures of chemical links in polymers ?
|
Acrylic, ester, amide, urethane
|
|
|
How is polymer response to heat classified?
|
Thermoset - when heat is added the polymer polymerizes and crosslink = set as solid. (liquid --> SOLID.). Irreversibly cured via heat, chemical reaction or irradiation.
Thermoplastic - heat breaks secondary bonds (i.e- wax) (solid-->liquid--->solid--->liquid) |
|
|
What is the classification types for PMMA (denture bases, denture teeth, temporary restorations)?
|
source - synthetic
texture - resin polymerization method - chain polymerization by-product - addition chain type - linear chain configuration - atactic structure of chemical link - acrylic response to hear - thermoplastic |
|
|
What is the classification for PBIS-GMA (restorative composite, bonding system, sealants) ?
|
Source - synthetic
Texture - Resin Polymerization Method - Chain Polymerization ByProduct - addition chain type - crosslinked chain configuration - atactic structure of chemical link - acrylic response to heat- thermoset |
|
|
What is the difference in classification of PBIS-GMA and PMMA?
|
PBIS-GMA is thermoset and crosslinked. PMMA is thermoplastic and linear.
|
|
|
What does percent conversion mean?
|
percent conversion is amount of monomer that gets converted into polymer during polymerization (also knows as DOC)
|
|
|
What is the typical percent conversion for a dental polymer?
|
DOC for most dental polymer-based materials is 65%-75% (3% shrinkage)
|
|
|
What is residual monomer?
|
Residual monomer is percentage of unreacted monomer at the end of the polymerization reaction.
|
|
|
What are free radicals for chain reaction polymerization?
|
They are unpaired electrons used as an INITIATOR that reacts with the double bond of the MMA monomer. Once activated, the monomers can react with more monomers to form a chain. (Benzoyl Peroxide used in dentistry) Anionic and Cationic species can also be used.
|
|
|
What are accelerators for chain reaction polymerization?
|
Accelerators are thermal, chemical (NN-DMTP), or light energy that is used to create free radicals and INCREASE THE RATE OF SETTING.
|
|
|
What are retarders and inhibitors for chain reaction polymerization?
|
Retarders/Inhibitors (hydroquinone) control the initiation step by absorbing free radicals and DECREASING the rate of reaction. This extends the storage and working time.
|
|
|
What is a composite?
|
A composite is a physical mixture of materials of different properties, mixture of metals, ceramics, and polymers
|
|
|
Why are composites better than pure metals?
|
Composites are better because they have better properties and are easier to handle that pure metals since the properties can be manipulated by changing the amount of each metal. Also, composites are stronger, light weight, and resistant to corrosion and abrasion.
|
|
|
What is the structure of dental composites?
|
Dispersed phase ( reinforcing filler of glass particles) and Continuous phase ( Resin matrix of BIS-GMA polymer)
|
|
|
What is the rule of mixture?
|
"The whole is equal to the sum of it's parts".
X = phase properties V = phase volume X = X1V1 + X2V2 + ... 70 psi = (20psi)(50%) + (120psi)(50%) |
|
|
What is the modified rule of mixture?
|
"The whole is equal to the sum of the parts plus their interfaces"
X = X1V1I1 + X2V2I2 |
|
|
What is the difference between auto cured and light cured dental composites?
|
Auto-cured (BIS-GMA)
|
|
|
What is used as an initiator for light cured composites? for auto-cured composites?
|
-light cured composites use camphoroquinone (blue light 450 to 470 nm)
-auto-cured composites use benzoyl peroxide. |
|
|
What is a coupling agent?
|
Coupling agents are bi-functional silicon-organic compounds that make covalent bonds between the resin matrix and filler.
|
|
|
Why are Silanes good coupling agents?
|
Silanes are the best coupling agent because they provide covalent bonding from matrix to filler, provide multi-layers, and dimerization. Silanes also require high Si-O filler content.
|
|
|
What is the filler phase in most dental composites?
|
The filler phase for most dental composites is BA glass, SiO2, inorganic colloidal silica
|
|
|
Why use Bis-GMA instead of MMA?
|
Advantages of Bis-GMA are less shrinkage (because it's a bigger molecule), less cytotoxicity, and stronger.
Disadvantages are impossible to crystallize, |
|
|
Why use nano-filled composites?
|
nano-filled composites have smaller particles that allow for tighter packaging, but they are not as strong as macro.
|
|
|
What is the general relationship between filer volume % and filler weight % in a dental composite?
|
50 volume % = 75 weight percent. Filler makes material stronger so we want as much material as possible (volume). Diff. in volume and weight because it is denser than matrix.
|
|
|
What is flowable composite?
|
It is a modified small particle filled and hybrid composite that have a reduced filler level so the mateial can flow readily to adapt to the dental anatomy of the cavity.
|
|
|
what is hybrid composite?
|
developed in an effort to obtain better surface smoothness and aesthetic characteristics than SPC. comparable in smoothness to to microfilled composites of anteriors.
|
|
|
What is packable composite?
|
It is composite that provides consistency of amalgams and have inceased strenght and stiffness.
|
|
|
What is oxygen inhibition?
|
Oxygen is the main inhibitor for most systems. top part of composite doesnt polymerize because it is inhibited by O2. When restorative material is added in increments, the O2 is displaced and the material copolymerizes.
|
|
|
How thick can increments of dental composite be? what is the general rule?
|
For light cured composite, increments of 2mm are recommended because any thicker and the light wont penetrate
|
|
|
What are the 2 critical factors for finishing and polishing?
|
abrasive size and filler particle size.
|
|
|
How much do dental composites shrink? What are the consequences?
|
at 65% conversion, there is 3% shrinkage. Internal contraction causes POROSITY formation, external contraction causes BOND stretching.
|
|
|
What is depth of cure?
|
depth of cure is thickness of a molecule that can be converted from monomer to a polymer under specific light curing condition. it does not cure uniformly and depends on shade, light intensity, and exposure time.
|
|
|
what are the different types of composite wear?
|
CFA - food bolus
OCA - impact wear FCA - sliding wear PCA- sliding wear TBA - abrasive wear *Composites in which the filler particles are small, high in concentration, and well bonded to the matrix are the most resistant to wear. |
|
|
Where does most CFA wear occur?
|
in the 1st molar, then 2nd molar, then premolars.
|
|
|
T or F: The single most important factor affecting success or failure of adhesive bonding in a clinical treatment is the operator's competence?
|
True
|
|
|
What is the smear layer?
|
organic residue resulting from cutting preparation.
|
|
|
What is the most important factor affecting success or failure of adhesive bonding?
|
operators competence
|
|
|
Is the flouride released from a glass ionomer effective in preventing secondary caries?
|
NO!
|
|
|
What is a "smear layer"?
|
A smear layer is the hydroxyapatite crystals that create a layer or plug of debri from cutting.
|
|
|
What is etch? What types are sold (1 bottle, 2 bottle)?
|
Etch removes the smear layer. There is a 3 bottle system of E + P + B which works best, there is a 2 bottle system (self-etching primer) of EP + B or E + BP, and there is a "self-etching" adhesive that is not very effective in removing the slime layer
|
|
|
What is the chemical composition of glass ionomers?
|
silicate cement (powder) + percarcoxylate (liquid). Resin modified glass ionomer (RM-GI) is a hydrophilic monomer that allows for better bonding.
*They are a mixture of glass powders and a liquid containing polyacrylic acid, the name "ionomer" refers to ion cross linked polymer, and describes the matrix of GI materials. |
|
|
What are effective fluoride release levels?
|
10-15ppm
|
|
|
What is the principle constituent of dental stones and plaster?
|
CaSO4*1/2H2O
|
|
|
what is gypsum used for?
|
molds and casts, impression material. NOT restorations
|
