Dental Materials Exam 3

gold foil is ______ or ______ using hand pressure or other mechanical means

compacted or condensed

in dentistry pure or nearly pure _______ is used to place small restorations

gold

components of a denture

White denture teeth and pink denture base

what is annealing gold foil

gold foil comes with a thin layer of a chemical protectant which is burned off with a 100% ethyl alcohol flame

acrylic resins as biomaterials

good material to cement artificial joints in place, still used today for this

a complete denture requires

precise adaptation to the supporting tissues and a peripheral "seal" for adequate retention

Pit and fissure sealants

preventive material applied to the susceptible pits and fissures of teeth to prevent or reduce caries

precipitation

process in which a solid is formed from the material dissolved in a liquid. EXAMPLE: freezing water, curdling of milk

Spherical alloys

sprayed molten metal into an inert atmosphere, droplets cool and produce these alloys

complete dentures are held in place by

suction, which is the result of surface tension and atmospheric pressure

Corrosion occurs both of the...

surface and in the interior of the restoration

the air inhibited layer has a ______ feel, and once final increment has been placed and no more composite is added, is removed with finishing of restoration

tacky

disadvantage of a chairside reline

that the new material is more porous and, typically, not as smooth as that of a lab reline

amalgam alloy

the Ag-Sn powdered metal before it is mixed with mercury

liners may change...

the bite or occlusion of a denture, causing trauma to the supporting tissues

Polishing can be delayed for ______ hours to allow the amalgam to set and become hard enough to withstand the polishing procedure

24

What are some indications that denture is not fitting well?

Frequent use of denture adhesives or OTC denture "cushion" materials or liners

working time of amalgam

(the time needed to condense and carve) is not directly controlled by the dentist, as it is with light activated composites

Low copper dental amalgam- (today high copper amalgams are the state of the art and dominate the market) composition

- 65% silver - 25% tin - 6% copper - 1% zinc (sometimes)

use of primers with sealants

- a primer can be used when rubber dam cannot be used - primer is believed to help the sealant wet a slightly contaminated surface and improve retention of the sealant

uses of composite cements

- able to bond restoration to the tooth surface - composite cements are the luting material of choice for ceramic restorations

esthetics

- all metal restorations may have acceptable or unacceptable esthetics depending on their location - ceramometal restorations adequately simulate the natural dentition in most situations - all-ceramic restorations reproduce the translucency of the natural dentition better than the ceramometal restorations and have the most life-like appearance of all restorative material

Manufacturer controls what of the alloy

- alloy composition - alloy particle size - Particle size - particle size distribution - also controls the rate of setting reaction by heat when treating the particles and by washing the surface of the particles with acid to remove surface oxides

aluminous porcelain

- alumina (alumina oxide) was added to porcelain to increase its strength - alumina is very strong ceramic material, and its addition slightly increases strength and clinical performance without affecting esthetics

wear

- because the ceramic materials used for ceramometal and all-ceramic restorations are very hard, they wear the opposing enamel much more than enamel or gold alloys - the softer gold alloys wear opposing enamel much like enamel does

Direct veneers

- bonded composites - these may not involve removal of significant tooth structure and in this case are considered to be a reversible treatment

requirements for ceramometal alloys

- casting alloys for ceramometal restorations have the same mechanical and biocompatibility requirements as alloys for all metal restorations - the ceramometal alloy must withstand the very high porcelain firing temperatures - it is important that the metal not melt or distort because the ceramometal alloy supports the porcelain during firing and clinical useq

margins

- casting techniques for metals result in more accurate margins than those for all-ceramic restorations - excessive gap at the margin of all-ceramic restoration increases the risk of recurrent caries; however, composite cements help to fill these gaps

four types of glass ionomer products

- chemical-cure glass ionomer products - resin-modified glass ionomer products - acid-base chemically activated resin-modified glass ionomer products - recharging fluoride in glass ionomer materials

Disadvantages of a complete lower denture

- chewing problems - lack suction/retention and will float and move around in the mouth - may cause "sore spots" and make speech difficult

use of dental amalgam

- class I, II, V, and VI carious lesions - foundation for a crown to restore a severely decayed tooth (known as amalgam build up or amalgam core)

metals

- classified as noble elements based on their lack of chemical reactivity. The noble metals include gold, platinum, palladium, and other inert metals

repairing acrylic prosthesis or appliances

- clean the surface - apply monomer - Apply new material that is mixed, applied to surface, and allowed to set. Polymer chains of old material is entangled in the new. (chemical bond is called quasi-chemical) - finish and polish

hybrid composite

- combination of a macro and microfilled composite - filler content is 75-80% - filler particle size average 0.5-1um in size but with a wider range of particle size from 0.1-3um - good physical qualities as conventional macro but more polishable because of microfill - most versatile; used for strength and esthetics and are acceptable for small to medium class I and II restorations and because their surfaces finish is nearly as good as that of microfills, they are also used for class III and IV restorations

Denture teeth

- come in a variety of shapes, sizes, and shades - acrylic resin teeth- most denture teeth are made from acrylic resin much like that used to construct the denture base - chemically bonded to the acrylic denture base during processing of the denture - porcelain teeth- much harder and more stain resistant compared to acrylic teeth, rarely used

denture base

- constructed on the master cast made from the final impression - the base is the pink part of the denture that sits on the alveolar ridge

use of amalgam with a cavity varnish

- copal varnish is a resin dissolved in a solvent - varnish is painted on the cavity prep and the intent is to reduce initial leakage by sealing the margins before corrosion products form

macrofilled composite

- first type of dental composite developed - filler is quartz materials with particle size of 10-25um - filler content is 70-80% by weight - large size of the filler particles in macrofilled composites results in a restoration that feels rough to the dental explorer and can appear rough to the eye - likelihood of plaque accumulation and staining is greater with macrofilled than with other types of composites - adequate for class III, IV, and V restorations, however, they are not the material of choice for restorative dentistry and their use is minimal

flowable composites

- flow into cavity prep because of their lower viscosity - a weaker, less abrasion-resistant material results - typically used as the initial increment of a composite restoration and then covered with a hybrid material

condensable composites

- have a filler particle feature that inhibits the filler particles from sliding by one another, resulting in a thicker, stiffer feel - they are condensable, but are not an improvement over hybrid composite materials

treatment planning

- knowing the periodontal status of the patient is critical. without a stable foundation, the long-term success of any restoration is unlikely - the endodontic status of the tooth must be considered - caries risk assessment and testing is becoming more common. Efforts to reduce the risk of caries should precede extensive and expensive restorations - enough tooth structure must remain to retain the restoration. Badly broken-down teeth may require buildups (cores) to provide retention for the final restoration

veneers

- thin layer of material that covers another material "like the shell of a hard boiled egg" - placed on the facial surface of anterior teeth to treat an esthetic problem - discolorations, rotation, or spaces (diastemas) can be corrected with veneers

Name the steps of the laboratory-processed reline

- lab makes impression, existing denture acts as a tray - send to lab - cast is poured - impression and cast are separated, impression material removed from denture - new acrylic material is added to fill the space between that denture and the cast - acrylic material is cured, finished, and polished in the same manner as construction - denture is returned to the dentist and given to the patient

Particles of amalgam alloy may be formed by two methods

- lathe-cut alloys - spherical alloys - Admixed or blended alloys

diagnosis

- loss tooth structure and missing teeth result from a variety of causes including caries, periodontal disease, trauma or fracture, esthetic concerns, and congenital deficiencies - teeth can also be lost as a result of restoration and re-restoration

use of composites for restorations

- material of choice for directly placed esthetic restorations - one of several materials called "tooth-colored" materials - they are still considered to be inadequate for the characteristic of life-like appearance when compared to all ceramic restorations - when compared to metallic, these do not have the same fracture toughness - hybrid composites dominate composite materials currently in use. They function well in moderate stress restorations where esthetics is of importance - composites do not have the mechanical properties for long-term success in large high-stress restorations such as cusp replacement restorations (size of restoration increases=stress of materials increase)

ceramometals

- metal ceramic combo that was developed for dentistry in 1950's - the tough, strong metal supports the weak but esthetic ceramic materials - called porcelain-fused-to-metal or porcelain-bonded-to-metal restorations and are considered to be an important "workhorse" in modern restorative dentistry

Metals

- most metallic indirect restorations are made by a casting procedure - casting involved melting the metal and then pouring or forcing the liquid metal into a mold - the casting process allows custom, complex shapes to be easily produced - work well in high stress situations, but their esthetics are poor

liquid chemically activated acrylic resin

- mostly monomer, methyl methacrylate - cross-linking agent, such as glycol dimethacrylate is added - inhibitor, hydroquinone, is most common one added - methyl methacrylate is a powerful solvent, and the ability for it to dissolve acrylic resin has a significant effect on the handling properties of acrylic resin systems

microfilled composites

- particle size is much smaller than macrofilled composites 0.03-0.5um - these polish very smooth and lustrous and the surface is very similar to that of enamel - low percentage filler (40-50%); therefore, the surface area requires much more resin to wet the surface of the filler particles; and the high resin content results in an increased coefficient of thermal expansion and lower strength - polymerization shrinkage of microfilled composites is less than expected based on the total resin content - microfills have lower modulus of elasticity and flex with the tooth better than the strongest composite materials, so they can be great for class V restorations

matrix of composites have several functions

- polymerizes to form a solid mass - bonds to the tooth structure

powder chemically activated acrylic resin

- polymethyl methacrylate resin with added colorants and benzoyl peroxide

acrylic resin system and porosity

- regardless of type of activation of acrylic resin system, porosity is a major concern - methyl methacrylate and other monomers evaporate easily at room temperature, and if this occurs during handling or processing, the resulting material will be porous - porosity weakens material and denture is likely to collect debris in pores in become foul

recharging fluoride in glass ionomer materials

- release fluoride which decreases over time - topical fluoride treatments can recharge glass ionomers fluoride releasing capability - result is a significant increase in the fluoride released by "old" glass ionomer material

light activated materials for polymerization systems

- single paste systems - no chairside mixing occurs - these set when exposed to a very bright light - working time is variable and can be quite long if operator desires - because of increased working time, these have replaced chemically activated composites, which are only used in areas where light cannot reach the composite material, such as when cementing a metal crown with a composite cement

Setting reaction of amalgam

- starts during trituration and progresses while condensation and carving are taking place

improved hybrid composites

- the average particle size has decreased and nano-sized particles have been added - reduced particle size result in slight improvements in strength and polymerization shrinkage

silicate and phosphate-bonded investments

- these are used to cast high-melting partial denture framework alloys and ceramometal alloys - they can withstand much higher burnout temperatures and are more difficult to use than gypsum-bonded investments

indirect veneers

- these use ceramic materials, such as porcelain - the facial surface is prepared to provide space for the veneering material; therefore, they are not a reversible procedure - they require an impression, a second appointment, and a lab fee and they cost more than direct veneers

composites shrink about _____% when they set

2%

ceramometal that strengthen porcelain materials

- to strengthen porcelain it is bonded to metal - advantage of metals include tough mechanical properties and ability to obtain a precise fit of the crown to the preparation - disadvantage is that metals are opaque to light even when used in very thin layers and light is not transmitted through the restoration as it is through tooth structure - a ceramometal restoration is not as natural or life-like in appearance compared to an all-ceramic crown

Advantages of using dental amalgam

- toughness and wear resistant - long-lasting, cost-effective restorative material (Class I=15-18 years, Class II= 12-15 years) - Amalgam has capability of sealing its margins during service, as the margins corrode, the tooth/restoration interface fills with corrosion products so that microleakage is reduced - Amalgam is the least technique-sensitive permanent restorative material that is available to the dentist - only material that might work when placed in a wet, contaminated environment - As the restoration increases in size, the stress within the restoration also increases, and the life expectancy of the restoration decreases

crowns

- used to restore teeth that have lost a significant amount of tooth structure - they are used when intracoronal retention is unavailable or when the tooth needs to be surrounded and held together by the restoration

ceramic materials

- used when esthetics are important - ceramic materials can simulate the natural colors and translucency of teeth - porcelain is the ceramic material most commonly used in dentistry - ceramic materials lack the toughness and fracture resistance required by bridges, but their esthetics can be excellent

air inhibition

- when composite materials are placed in increments, each increment chemically bonds to the previous one

steps in creating a denture

1. a baseplate and wax rims are constructed from chemically activated acrylic (or similar material) and baseplate wax, made precisely to fit on patient's ridge 2. the wax rims on the baseplates are used to determine the patient's midline, "plane of occlusion" and size of the denture teeth, plane of occlusion is the plane where the upper and lower teeth meet when a patient bites 3. At the same appt, the patient's bite is recorded and is used to position the upper and lower casts in the same relationship as the supporting tissues in the mouth 4. With the aid of baseplates and rims, the casts are mounted on an articulator using dental plaster 5. Denture teeth are "set" in the wax. When all the denture teeth are set in wax, it is called a denture setup. a setup stimulates proper bite (relationship of the two arches), the vertical dimension, and esthetics of final denture 6. Before processing, the setup (the baseplates with the teeth set in wax) is placed in the patients mouth. The procedure is called the "wax try-in" this wax try-in allows the dentist to check function, occlusion, and phonetics before the actual denture is processed

Placement of a composite restoration

1. dentist diagnosis the lesion 2. a determination of the shade that will be used is made 3. dentist cuts cavity preparations, including beveling of margins 4. area is isolated with cotton rolls, dry aids, or preferably a rubber dam 5. Determine need for cavity liner 6. etch, prime, place, and cure adhesive 7. Incremental placement and curing of composite material 8. Finish (proper anatomical contours) 9. Check for proximal contacts 10. examine for voids and marginal defects with a mirror and explorer. Use dental floss to detect any overhangs 11. Polish (lustrous surface) 12. Remove rubber dam or other isolation materials 13. check occlusion

Processing the denture

1. embedding the master cast and the denture setup in a denture flask filled with gypsum material. The mold is opened, and wax/baseplate are removed while denture teeth stay in position. Acrylic resin is placed when doughy, mold is closed, and acrylic forms denture base 2. The closed mold is heated in a water bath to activate the heat-cure acrylic resin. The heating rate is controlled to reduce porosity. The application of pressure minimizes loss of the volatile monomer; loss of monomer results in porosity and weak spots 3. After processing, the denture is removed from the mold by breaking the surrounding gypsum materials. It is then finished, polished, disinfected, and delivered to the patient.

technique to placing dental sealants

1. isolation 2. surface cleaned with slurry of pumice 3. tooth is etched and rinsed with water 4. sealant is placed 5. if chemically activated, allowed to set, if light activated, which is most common type of sealant placed today, then a light is used to cure 6. floss is used to ensure no materials flowed into interproximal areas 7. occlusion is checked and adjusted if needed

improper relationship to teeth results in...

1. overworked muscles of mastication 2. poor phonetics 3. unsatisfactory esthetics

placement of PRR

1. suspicious pit is opened with a bur by the dentist, and existing caries is removed 2. tooth is etched and primed, and adhesive is placed 3. prepared pit is filled with a hybrid composite material 4. any pits and fissures not filled by the composite or adhesive are filled with sealant 5. a great deal of tooth structure is preserved by placing a PRR

air abrasion system

1. used to remove debris and decay from pits and fissures and then placing sealants and preventive resin 2. high velocity stream of air carries very hard ceramic particles (aluminum oxide) and abrades the tooth 3. these systems are different from the prophy jet that uses baking soda to remove stains from surfaces of teeth 4. air abrasion systems can effectively cut enamel and dentin, cut cavity preparations, and remove composite materials 5. a rubber dam is recommended to protect patient's airway from the dust and debris that result from an air abrasion system

process of lost-wax casting technique

1. wax pattern with the sprue attached 2. wax pattern attached to the sprue base (also called the crucible former) and the casting 3. Wax pattern and casting ring with a paper liner. the casting ring slips over the wax pattern and fits into sprue base 4. Sprued and invested wax pattern inside a sectioned casting ring 5. cross section through a casting ring after burnout and a completed casting 6. Completed casting on the die

Admixed or blended alloys

A mixture of both lathe-cut and spherical particles

What is the process of relining?

Add a small amount of new materials to the inside tissue area of the denture base to replace the additional alveolar ridge that has been lost since the denture was made

gold foil is limited to small class _____, ____, _____, and _____ restorations because it lacks strength compared to other metallic restorations

I, II, III, and V

why would we need to reline?

Ill fitting dentures due to alveolar ridge atrophy and resorption

preventive resin restoration (PRR)

a conservative approach to treating pit and fissure decay

considered by many to be the "state of the art" material for luting metal and porcelain fused-to-metal crowns

acid-base chemically activated resin-modified glass ionomer products

Mesh

acrylic resin flows into and ground when the partial denture is processed

______ ______ were first introduced in dentistry for denture bases

acrylic resins

polymerization systems

all dental composites use addition polymerization and two polymerization systems are used to convert matrix-filler paste to a solid composite material

fracture

all-metal restorations are least likely to fracture - mechanical failure of the metal substructure of ceramometal crowns almost never occurs, however fracture of porcelain is the most common type of mechanical failure

Powdered metal is called an...

amalgam alloy - predominantly silver (Ag) and tin (Sn)

the mixing process of amalgam is called

amalgamation or trituration - mechanical device called an amalgamator or triturator is used

fixed indirect restorations can be classified in two ways:

amount of tooth structure they restore - by the materials from which they are made

CAD/CAM

an "optical" impression, rather than a physical impression of the preparation is made, and the restoration is machined out of a solid piece of high-strength ceramic material through computer control in the dental office or lab

a complete denture or full denture replaces

an entire arch of missing teeth, alveolar bone, which absorbs when teeth are missing

high copper amalgam was introduced when

around 1960, increasing the copper reduced the percentage of the weakest phase of the resulting dental amalgam

polymerization shrinkage

atoms and molecules become packed much closer together when polymerized, and the resulting material is smaller in volume than the starting components

______ ______ to tooth structure reduces the potential for these gaps and the resulting microleakage

bonding materials

Detecting composite restorations

can be difficult due to good shade match or excellent margins - do feel a bit softer than enamel to a sharp explorer - they can appear radiopaque or radiolucent on radiographs, depending on filler particle; however, they have evolved to be more radiopaque, which aids in the detection of these

thermoplastic polymers

can be heated (thermo) and molded or shaped (plastic) after the polymerization reaction, similar to wax

fixed restorations

cannot be removed from the oral cavity, they are luted (cemented) in place

tin

causes setting contraction and decreases strength and corrosion resistance

silver

causes setting expansion and increases strength and corrosion resistance

sintering

changes the porcelain from a powder to a solid - after sintering, the final shape of the restoration is refined by grinding

what is the first true adhesive restorative materials

chemical-cure glass ionomers products

framework is composed of

clasps, connectors, and mesh

precious metals

classified based on their cost. Noble metals and silver

hard tissue lasers are ideal for what?

cleaning debris from pits and fissures when placing sealants and preventive resin restorations

acrylic resin systems used in dentistry

cold-cure or chemically activated acrylic resins (supplied as powder/liquid)

composite materials

combination of two materials resulting in a material that is superior to either component alone

complex restoration

combine the features of inlay, onlay, and crown restorations

_____ ______ replaced both acrylic resins and silicate restorative materials

composite materials

Mercury toxicity

concern in dentistry because mercury and its chemical compounds are toxic to the kidneys and the CNS - not a problem for patients, except for patients who may have an allergy to mercury and very few cases, <0.1% have been reported - not ethical for dentist to urge patients to replace them

temporary restoration

constructed and cemented at the time of the preparation

most dental resins are ____ _____ and therefore thermoset

cross-linked

overtriturated amalgam tends to

crumble and is difficult to condense. In addition, voids will likely result in the restoration

there is a limit to the amount of filler that can be added, as it can cause a _______ ______

defective product

when _____ _____ became available, direct acrylic restorative materials were made obsolete

dental composites

Immediate denture

denture that is placed at the same appointment during which the remaining teeth are extracted

final step in the treatment plan

determine the recall status of the patient based on periodontal concerns, caries risk, chronic problems, and oral hygiene home care practices

filler size

determines surface smoothness or resulting restoration - composites are classified by the size of their filler particles - There are three categories that will be discussed in the book: macrofill, microfill, hybrid; however, it is important to know a new category has been introduced known as a nanofilled composite

gold foil is also called...

direct gold or cohesive gold

Lathe-cut alloys

done by grinding an ingot of metal to produce fillings

a partial denture uses a cast metal ________ for retention

framework

additional polymerization is an ______ reaction

exothermic it means they release heat

true or false: dental hygienists cannot place dental sealants

false, they can

true or false: polymeric materials have low coefficients of thermal expansion compared to tooth structure

false; high coefficients

true or false: an immediate denture does not protect the extraction sites during healing

false; it does protect

true or false: fiber-reinforced composites are much more brittle and weaker than particle-reinforced composites

false; much tougher and stronger

true or false: composites do not chemically bond to primers and adhesives

false; they do

sintered

firing porcelain causes the powder to become sintered

special use composite materials

flowable and condensable composite materials

The triturated material is reacting or setting while it is...

forced, or condensed, into the cavity prep

crazing

formation of many shallow surface cracks

acrylic resin

hard, brittle, glassy polymers - handled more like a thermoset material, after it sets, it is not heated and molded - most common is methyl methacrylate

undertriturated amalgam

has a mushy-grainy feel because not all of the particles are broken up. The mass is difficult to properly condense

Thermoset polymers

have cross-linked rather than linear structures and tend not to melt; rather, they decompose

Most dentists use ______ _____ alloys

high copper

why are dental composites placed in layers and cured after each layer

if not fully cured, pulpal irritation and post-operative sensitivity are more likely to occur

procedure of immediate dentures

impression is made, denture constructed in lab, remaining teeth are extracted, denture is placed, post op instruction given to patient

fillers

in beginning, fillers in dental composites were naturally occurring quartz materials (sand). Recently, manufacturers have "engineered" glass materials for dental composites - these glass materials are formulated to have the proper strength, hardness, and chemical as well as optical properties for use in dental composites

as filler content ______, the resin content _____, therefore, polymerization shrinkage decreases, and the coefficient of thermal expansion becomes more like that of tooth structure. Hardness and abrasion resistance increases as well

increases, decreases

CAD/CAM equipment is utilized to fabricate ______ restorations

indirect

reactions of chemically activated material is initially delayed for several minutes by the presence of a chemical reaction called an

inhibitor

inlays

intracoronal (inside the crown) restorations that replace small to medium amounts of tooth structure - they are most commonly used to restore pits, fissures, and grooves (class I) as well as proximal surfaces (class II) or posterior teeth, however, they do not restore the cusps - they are retained by using luting cement

Properly triturated amalgam

is a cohesive mass that might be slightly warm to the touch. The surface is smooth and this mix is easy to condense and exhibits the proper working time

Poor condensation with defects at the margin increases

likelihood of recurrent decay

dentistry has used the "______-______ _______ technique" for a century to produce metal restorations

long-wax casting

Shades and opacities of dental composites

manufactured in several shades to match the color or translucency of teeth - by layering materials, with different shades and translucencies a more natural result can be obtained - opaque composites are used to hide stained or discolored dentin

Polymers

materials that are made of large, long molecules formed by chemically reacting molecular building blocks called monomers, together to produce a polymer via polymerization

elongation

measure of the ability of a material to be stretched before it breaks - used to predict the ability of an alloy to be burnished, which when burnishing occurs it pushes the metal against the tooth to close any gap between the tooth and the casting, therefore, a margin or gap between the restoration and the tooth becomes smaller when it is burnished

What is dental amalgam?

metal alloy of which one of the elements is mercury - made by mixing approx. equal parts (by weight) of powdered metal alloy with liquid mercury

Clasps

metal and adjust fit

alloys

metals that are a combo of several elements

titanium

most biocompatible metal - current titanium used is limited - titanium has been used as material of choice for dental implants for decades - if handled properly, titanium can osseointegrate with bone

Restoration design

most common factor influencing the design of a restoration is the patient desire for an esthetic restoration - the attrition (wear) rate of the restoration should be considered - biocompatibility of the material must be considered - location of the margins of a restoration may be placed above the gingiva or in the gingival sulcus. Margin location affects esthetic retention, periodontal response to the restoration, and likelihood of recurrent caries

additional polymerization is called this because

one monomer at a time is added to the polymer chain as the reaction proceeds

Porcelain

porcelain jacket crowns were the first all-ceramic restorations used in dentistry- the entire crown was made of porcelain

cavity prep is always ____________ with amalgam

overfilled

a caries risk assessment should be made to determine

past history of caries, diet, salivary flow, and buffering capacity, fluoride exposure, and oral hygiene

the advantage of a chairside reline

patient does not go without his or her denture

Classification by gold content

percentage is parts per 100 - carat is parts per 24 - fineness is parts per 1,000 - Therefore: 75%=18 carat=750

surface corrosion discolors an amalgam restoration and may even lead to

pitting

incremental addition

placement of composite in layers, and not only assures adequate polymerization, but provides a secondary benefit as well

________ reactions make a few very large polymer molecules from many small monomer molecules

polymerization

microleakage

polymerization shrinkage has potential to open gaps at margins of restorations

processing a partial denture

processed much like a complete denture; however, acrylic resin must flow through and around the mesh of the framework

_____ _____ is not used because it is too soft, this is why other elements are combined to gain the strength needed

pure gold

the quality of an amalgam restoration is ______ if it is placed on a wet or contaminated environment

reduced

polishing produces a smooth and lustrous surface that...

reduces both the likelihood of corrosion and the ability of plaque to adhere to the surface

zinc

reduces the oxidation of the other metals in the alloy

if a prosthesis can be removed by patient, it is called...

removable partial denture, or simply a partial denture

excess amalgam is ___________ to restore the original anatomy of tooth

removed (carved)

percolation

repeated expansion and contraction of polymeric restorative materials can open and close gaps at the margin of a restoration - results of this are an increase in leakage resulting in greater chance of caries

onlays

replace more tooth structure than inlays - onlays restore one or more cusps and, at times, the entire occlusal surface of a tooth - these can be used when likelihood of cusp fracture is high as it protects the cusps from occlusal forces - retained by luting cement

dental bridge

replaces missing teeth - typically a bridge has a crown, called a retainer, at each end - retainers are supported by abutments - replacement teeth are called pontics - a bridge may replace one tooth or several teeth

also called resin-reinforced glass ionomers

resin-modified glass ionomer products

these are popular for class III and V restorations

resin-modified ionomer products

process of a chairside reline

same material acts as impression material, it is mixed, placed in denture, and placed in mouth. Material sets and becomes rigid. Excess is trimmed, denture is polished and returned to patient

Dual-cure materials

several dental materials have both chemical, and light activated capabilities - polymerization is started with a curing light, but materials that cannot be reached by the intense light sets via the chemical-cure mechanism

matrix

soft, weak, flexible, and prone to wear when compared to the filler - matrix of dental composite is a polymer, typically bis-GMA or a similar monomer and an organic chemical called a diluent, which is added to control the viscosity of the final product

open interproximal contacts, overhanging margins, and other improper contours increase

the likelihood of periodontal problems

Dental amalgam

the mixing of powdered metal with mercury

functional group

the part of the molecule responsible for its important chemical properties

to obtain maximum benefit from addition of filler and silane particles...

the polymer is bonded to the filler particle with a coupling agent

creep

the slow change in shape caused by compression

light activated additional polymerization

these are supplied in a single paste and no mixing is required - the polymerization process does not begin until the material is exposed to a very bright light source - the "set on demand" makes these materials very popular, composite restorative materials being the most common

chemically activated additional polymerization

these materials are also supplied as a powder/liquid system (temp crowns, retainers, impression trays, etc.) - powder and liquid are mixed together to start the polymerization process

heat activated additional polymerization

these materials come from manufacturer as a powder/liquid system - the polymerization does not start until the material is heated typically in a hot water bath

connectors

thicker parts of framework. Connect the mesh/clasps together

depth of cure

thickness of composite that is cured by a light source

indirect restorations

those that are constructed outside of the mouth

What can long-term use of adhesives cause:

tissue inflammation

undercarved occlusal surfaces cause

trauma to the supporting tissues

true or false: a lower partial denture with a few remaining natural teeth to hold it securely functions far better than a complete lower denture

true

true or false: chemical-cure glass ionomer products are susceptible to dehydration during the initial setting of the material and the finishing of restoration, and if not protected from dehydration, surface crazing occurs

true

true or false: curing light can only penetrate through several millimeters of composite to polymerize the underlying material

true

true or false: dental composites use ceramic filler particles with silane coupling agents

true

true or false: light activated glass ionomer restorations are easier to place and finish, and they are not as sensitive to dehydration as their chemical cure counterparts and are stronger and tougher

true

true or false: polymers without filler additives are not suitable for use as restorative materials

true

Chemically activated materials for polymerization systems

two paste systems - paste are different colors and they are mixed until the two colors blend into one - when mixing the two pastes air bubbles are incorporated during mixing, which can lead to weakness of the set material and increased staining - when pastes are mixed, inhibitor destroys the free radicals that are produced for a short period of time, which results in a limited amount of working time because when inhibitor has been reacted completely polymerization begins

filler particles

typically inexpensive, strong, hard ceramic materials

compomers

used to describe materials that bond and set like dentinal bonding/composite systems but that initially release some fluoride like glass ionomers

chairside reline

uses different material than lab-processed reline

heat-activated acrylic resins

very similar to chemically activated systems, except there is no chemical activator in the liquid - less inhibitor is present in liquid and only required as a preservative that prevents polymerization during storage - supplied as powder/liquid similar to cold-cure resins - much longer working time - after material is formed into the desired shape, material is heated in a water bath - heat breaks down benzoyl peroxide, forming free radicals - polymerization proceeds by changing dough into a rigid material - products that are heat-cured are a bit stronger and tougher than cold-cure acrylic resin

if fillers are not properly wetted by the liquid monomers, _____ and _____ between the filler particles result

voids and gaps

an inadequate mercury/alloy ratio results in...

voids and poor restorations

matrix is the _______ and least wear-resistant phase of dental composite material

weakest

When is the amalgam considered a zinc containing amalgam?

when the zinc content is greater than 0.01%

galvanic corrosion occurs when?

when two dissimilar metals exist in a wet environment - the electrical current flows between the two metals, and corrosion (oxidation) of one of the metals occurs)

silane coupling agents

work like soap - long molecules that react with polymer matrix at one end with the ceramic filler at the other end