Biomaterials

Front 1

Tensile strength(diametral tensile)

Back 1

For amalgam it is one hour. It indicates rate of strength build up, important in class 2 preps, and also spherical faster than admixed.

Front 2

Rate of strength development

Back 2

90% within 8 hours. Maximun strength after 7 days or more.

Front 3

Tensile stregth of amalgam and gamma phases

Back 3

Amalgam tensile strength is 450-600. Gamma phase is 1750, gamma 1 is 1100, gamma 2 is 280.

Front 4

Compressive strength and marginal breakdown

Back 4

the higher the slow compressive strength the less the observed rate of marginal breakdown.

Front 5

Amalgam cavosurface margin

Back 5

as close to 90 deg as possible.

Front 6

Creep

Back 6

dimension change under load on a fully set specimen. The lower the creep value the lower the rate of marginal breakdown.

Front 7

Static creep

Back 7

Constant load 360 kg/cm^2 for 24 hours

Front 8

Dynamic creep

Back 8

alternating compressive and tensile loads over a given time period.

Front 9

Undermix(trituration)

Back 9

dry, crumbles. It has a low compressive strength, excessive expansion.

Front 10

Overmix(trituration)

Back 10

It is plastic ans clings to the capsule, it flows. It has high compressive strength, also may have reduced or negative expansion.

Front 11

Dental amalgam vapor

Back 11

is soluble in blood and is distributed to different systems. Most toxic form is methyl Hg which is readily absorbed thru gut and rapidly distributed.

Front 12

conventional amalgam alloy composition: Ag

Back 12

where Ag is 67-74%, has strenght and hardness but is difficult to handle and sets rapidly. High Ag content means a greater expansion during setting.
Increases expansion and compressive strength.

Front 13

Conventional amagam: Tin composition

Back 13

25-28% Sn, aids in amalgamation, reacts with Hg at room temperature. it reduces expantion when it is greater than 28%, it REDUCES corrosion resistance.
Decreases expansion and increases flow.

Front 14

Conventional amalgam: Cu

Back 14

0-10%, increases strength and hardness, setting time is more uniform.
Decreases flow.

Front 15

Conventional amalgam: Zn content

Back 15

aid in manufacture(its an oxide scavenger during casting). Greater than .01% causes excess expansion when it reats w/ H20 from any source.
Decreases expansiona nd compressive strenght.

Front 16

Spherical amalg alloys

Back 16

molted metal sprayed into inert gas. Advatage: space distribution of alloy less Hg to mix low Hg technique adaptation excellent, faster rise in strength.

Front 17

Disadvantage of spherical alloys

Back 17

maintaining adaptation during carving

Front 18

High Cu admix alloy

Back 18

blendin components: add alloy (30% by weight) spheres of silver copper eutectic( 72% Au 28% Cu). Get alloy fillings and AgCu spheres.

Front 19

Amalgamated allay

Back 19

intermetallic compound about the dispersant particle (AgCu) found to be Cu3Sn + Cu6Sn5(Asgar Mahler phase). There is gamma 1 but little gamma 2 present.

Front 20

Results of high Cu admixed alloys

Back 20

superior results:
low tarnish, maintains polish.
-low rate of mraginal breakdown- this is substantiated in several 3 - 4 yr clinical studies.

Front 21

High Cu single composition alloys

Back 21

major componeys prepared in single melt with the composition of Ag3Sn2. (Cu 9-29%).

Front 22

High Cu single composition (ternary alloy)

Back 22

major components prepared in single melt with composition of Ag3Sn2(Cu 9-295). Rapid cooling required for proper strcuture. Its amalgated alloy has no Sn present but u find Cu3Sn and Cu6Sn5.

Front 23

Single Cu admixed alloy

Back 23

high Cu lathe cut and high Cu sperical.

Front 24

Cements requirements

Back 24

nontoxic and nonirritant to pulp and tissue. Insolouble in saliva nd liquids taken in mouth. Should develop sufficient strength and protection of the pulp from effects of other restorative material. It should be bacteriostatic if inserted into a cavity with residual caries.

Front 25

Electrical insulation of cements

Back 25

under metallic restoraion to minimize galvanic effects.

Front 26

Zinc Phosphate cement

Back 26

used for cemntation(luting) of fixed cast alloy and percelain restorationd and orthodontic bands.

Front 27

ZnPO4 composition

Back 27

powder: mainly zinc oxide w/ up to 10% magnesium oxide and small amounts of pigments. Water content controls the ionization of the acid and thus the reaction rate w/ the powder. The set cement consists of a cores structure of residual ZnO particles in phosphate matrix.

Front 28

ZnPO4 Properties

Back 28

USES:Cementation of fixed cast alloy and porcelain rest, ortho bands; also used in past as cavitu lining or base.
compressive strength:12,00-16,000. Solubility-Dsiintegration: .3% by weight over first 3days. Film thickness- 40 to 25 microns. Setting time: 4-9 mins, working time is increased by using cold slab.

Front 29

Increased powder/liq mixture for ZnPO4

Back 29

gives more viscous mix, shorter setting time, higher strength, lower solubility and less free acidity.

Front 30

Biological effects of ZnPO4

Back 30

initial pulpal irritation due to its acidity and osmotic properties. It may permit marginal leakage which can result in pulpal pathology.

Front 31

Advanatages of ZnPO4

Back 31

handles easily, has good record of clinical durability. High compressive strength, low film thickness values.

Front 32

Disadvantages of ZnPO4

Back 32

Brittleness, solubility in organic acids and oral fluids, pulpal irritation(liner must be used in deep cavities), lack of adhesion to tooth structure which leads to leakage.

Front 33

ZnO-Eugenol properties

Back 33

USES: Temp cementation of rest, cavity lining , temp fillinfmat.
low compressive strength: 100 to 1000 psi. Tensile strenght is very low. High solubility, 1.5% by weight in distilled water in 24hours. Film thickness si about 40 micros.

Front 34

Advantages/disadvantages of ZnO eugenol

Back 34

Bland and obtudent effect on pulp, good sealing ability and resistance to marginal penetration.
Disadvantage:
Low strength and abrasion resistance, soluble and disintegrates in oral fluids. Also little anticariogenic action.

Front 35

Reinforced ZnO eugenol cements properties

Back 35

USES:cementing for restoration, cavity lining and base mat; also temp filling mat.
Strength:5000 to 8000 psi, tensile strength: 700 to 900 psi. Solubility seems to be lower than zno eugenol. Thickness is from 35 to 75 microns. Have long working time

Front 36

Biological effects of reinforced ZnO eug.

Back 36

bland and obtudent on the pulp, some inflammatory rxn in connective tissue,

Front 37

Advantages/disadvantages of ZnO eug

Back 37

advan: minimal biological effetcs, good initial sealing properties, adequate strength for final cemetaion of restos.
Disad: lower strength, higher solubility and disintegration than zinc phos cements, hydrolytic instability, softening and discoloration of some resin restorative materials.

Front 38

EBA cements properties
(ethobenzoic acid- 50 to 66%, little ZnO)

Back 38

USES:Cementing inlays,crwons,bridges; as a base or lining mat; temp filling. Strength: 8000 to 1000psi (similar to ZnPO4) by increasing powder/liq ratio; tensile strength: lower about 500 to 800psi. Solubility similar to ZOE. Thickness: 40 to 70microns. Setting time: 7 to 13mins.

Front 39

Biological effects OF EBA

Back 39

similar to ZOE materials- bladn obtudent on the pulp.

Front 40

Advantages/disadvantages of EBA

Back 40

Advantage: strength and flim thickness are comparable to those of ZnPO4 cements, little irritant effect on the pulp, long working time.Disad: high powder/liq ration for optimum properties, neccessitating long mixing time,, hydrolytic breakdown in oral fluids.

Front 41

Polycarboxylate compounds

Back 41

USES: cemeting cast alloy and porcelain resto and ortho bands; cavity liners;temp filling mat. Strength: 9000 to 12000 psi, tensile strength: 800 to 1000 psi. Strength increases with powder/liq ratio, also increased by additives such as alumina and stannous fluoride. Solubility:.05% after 7 days. Thickness: 25 microns. Setting time; 5 to 8mins, affected by powder/liq ratio, eactivity, part size, additives , mw and conc of polyacrylic acid. Adhesion to dentin may be limited but on clean surface can occur thru Ca complexation.

Front 42

Biological effets of ploycarboxylate compounds

Back 42

bland effetc on pulp similar to ZOE. Related to rapid rise of pH towards neutrality, min movement of fluid in dentin tubules in response to cement.

Front 43

Advantages/disadvantages of Polycarboxylate

Back 43

Advan: strength, solubilty, film thickness comprable to ZnPO4, easy mixing, little pulpal rxn. Dis: accurate proportioning req for optimum properties, moderate compressive strength, clean surfaces required for proper bonding and short working time.

Front 44

Glass Ionomers cements properties

Back 44

USES: luting cement, filling mat for erosion cavities, pit n fissure sealant, liner underneath other rest mat. Strength: 20,000psi, diametral strength is lower about 1600psi. Solubility: depending on powder/liq ration around .3 to 3%.

Front 45

Biological effects

Back 45

Pulpal rxn is similar to ZnO carboxylate cements, mild compared to silicate cements.

Front 46

Resin modified GI: Self cured

Back 46

modified polyacid w/ acrylate groups. cement has both acid-base rxn and polymerization by mircoencapsulation of catalyst in powder.

Front 47

Light cured Resin modified GI

Back 47

modified polyacid w/pendant acrylate groups for polymerization cross linking rxn. Cements has both acid-base rxn and polymerization by light curing. Increased physical properties, adhesion to enamel and dentin w/ reduced mircoleakage and very low solubility.

Front 48

Resin cements(luting)

Back 48

types: methylmethacrylate based, BISGMA based. Uses: limited due to pulpal response, film thickness a concern for early types. Advantage: very high strength, very low solubility.

Front 49

GI trad composition

Back 49

-polyacid
-liq thin: water with 4-5% tartaric acid, gives longer shelf life
-liq thick: constituted polyacid at 40% in water, limits shelf life to 1 year.
-powder- basic glass to react w/ midly acidic liq; 2 pahsed silica glass formed.

Front 50

Bonding to enamel and dentin- of GI

Back 50

enamel bonding by rxn of polyacid w/ Ca2+ on surface. bond strength limited by cohesive strength of the GI. dentin bonding improved by modification of the smear layer(mild acid for 10-20 sec).

Front 51

metal modified GI

Back 51

adding amalgam->set quickly but bonds less. silver particles has better physical properties. Bonds well to dentin but is too weak for core mat for crowns. Has increased wear resistance compared to normal GI.

Front 52

Initial GI rxn

Back 52

involves surface dissolution of glass powder releasing Al,Na, Ca ions- Na and Ca react to form ionomers. this step: sensitive to water.
Later rxn- sub Al for na,ca ionomers, new Al bonds for more xlinked structure. This step is sensitive to dessication. have to coat surface immediately after removal of matrix w/ varnish or resn bonding agent.

Front 53

Composite resin

Back 53

it is compromised of a continuous or matrix phase of resin in which there is discontinuous or dispersed phase of another material. eg fiberglass is a type of com resin , glass fib embedded in a matrix of fibers. The dispersed phase help reinforce the matrix phase.

Front 54

Role of filler particle

Back 54

strength, reduce shrinkage, increase wear strength, reduce coeeficient of thermal expansion.eg enamel 12,resin 70-100, composite 20-40ppm. interract w/ matrix resin, bonding the particle to the resin. Filler is 65-85% wt

Front 55

Paste-paste system(self curing) - Universal paste

Back 55

contains peroxide

Front 56

Catalyst paste

Back 56

contains tertiary amine in place of the peroxide. dark yello color.

Front 57

One paste system

Back 57

uses visible light to cause the breakdown of alight activated ring compound to form initiating free radicals.

Front 58

coupling agent for paste compostion (resins)

Back 58

silane which contains a vinyl or methacrylate group enter into the resin polymerization.

Front 59

conventional

Back 59

filler size: 5-50 microns, filler type: quartz, radio opaque glass.

Front 60

Microfilled resin

Back 60

filler: fumed silica(.02-.04 microns). paste has large particles due to method of fabrication. compared to conventional: brittle, low elastic moduus, high coeff of thermal expansion, H20 absroption ofset by shrinkage, high strength:compression, tension , transverse.

Front 61

Hybrid/Blend

Back 61

filler size: .5-5 microns, matrix has fumed resin, it controls resin- toughness and handling viscosity.

Front 62

Composite wear

Back 62

conventional: uniform loss, contact area wear.
MICROFILLED: margin ditching, localized wear in contact areas.
Hybrid; uniform wear at low rates