Exam2 Flashcards

Question

Shading

Answer 1

New ceramics are pre-shaded and layered

Answer 2

Monoclinic to Tetragonal...stopping short of cubic

Answer 3

COS, Impression Perfect: 74, 48% High: 18%, 46% Light: 8%, 6% Lava COS- better results (P <0.05)

Answer 4

COS, Impression Perfect: 62,43% Tight: 38%, 57% Lava COS- better results (P <0.05)

Answer 5

COS, Impression Perfect: 92%, 70% Loose:8%, 30% Lava COS- better results (P <0.05)

Answer 6

COS, Impression Yes: 95, 89% No: 5, 11% Lava COS- better results ( p< 0.05)

Answer 7

COS 63%, Impression 8%, No preference 29%

Answer 8

Strength (120 to 1200 MPa), Esthetics (anterior vs posterior) patient factors

Answer 9

Feldspathic porcelain (CEREC Blocs), Leucite-reinforced porcelain (IPS Empress CAD), Lithium disilicate ceramic (IPS e.max CAD)

Answer 10

Feldspathic porcelain (100-120 MPa) , Leucite- reinforced porcelain (120-140 MPa), Lithium disilicate ceramic (375 MPa) (IPS e.max CAD)

Answer 11

Zirconia (BruxZir Solid Zirconia, BruxZir Anterior, Lava Crowns & Bridges, Lava Plus, NexxZr) Flexural strength (500-1500 MPa), Veneered core and framework and full-contour restorations

Answer 12

> 90% zirconium oxide (ZrO2), stabilized with 3-5.4%, Y2O3, HfO2, Al2O3; small grains with no glassy phase, no silica- special primer for bonding

Answer 13

Esthetics- excellent, strength- very high, fit- excellent, metal- free, clinical track record (10 year Lava recall, 4 year BruxZir recall, 1 year, NexxZr recall, 1 year BruxZir Anterior recall)

Answer 14

Material, 2010, 2016 BruxZir, 10,000/mo, 143,000/mo* IPS e.max, 10,000/mo, 26,000/mo PFM, 25,000/mo, 19,000/mo *BruxZir Solid Zirconia 87% BruxZir Anterior 13%

Answer 15

over 1300 Lava restorations placed since 2003, 1008 restorations recalled, molar crowns, pre-molar crowns, anteriors, bridges, and implant abutments Resistance to fracture and chipping- fracture rate (6% required), replacement- molar> premolar, chipping rate 4.7%, No fracture/chipping 89%

Answer 16

Undersupported, underfired

Answer 17

1392 zirconia restorations placed- cemented with self- adhesive and adhesive resin cements; 913 restorations recalled at 4 years; single crown (77%) bridges (16%) and implant crowns (7%) most restorations had no chipping or fracture, one crown and 2 implants failed; esthetics- excellent great for patients who wanted B1 shade; 5 restorations exhibited slight marginal discoloration, minimal wear on restorations and on opposing dentition, 39 of 913 (2.8%) crowns debonded and were recemented

Answer 18

278 NexxZr T full contour restorations placed; 4% of restorations required minor occlusal adjustment at placement; single crown (88%) bridges (11%) and implant crowns (1%)

Answer 19

179 restorations recalled at one year, one premolar crown exhibited chipping, no restorations required replacement, esthetics- excellent; excellent resistance to marginal discoloration with self adhesive and adhesive resin cements; no wear observed on restorations or on opposing dentition

Answer 20

``` BruxZir Anterior (Glidewell Laboratories), Katan UTML (Kuraray Noritake Dental), Lava Plus (3M), Origin Beyond (B&D Dental technologies) Vericore ZR HTX (whip Mix Corporation) * improved translucency but lower flexural strength ```

Answer 21

Katana UTML, Kuraray Noritake Dental | 35% enamel layer, 15% transition layer 1, 15% transition layer 2, body (dentin) layer 35%

Answer 22

``` Zirconia (7.1-7.8) Lithium disilcate (13.8-15.8) Resin ceramic (14.9- 17.7) What value of TP is ideal clinically? Stump shade important ```

Answer 23

Zirconia- (0.1-0.15um), lithium disilicate (0.28-0.37um), resin ceramic (0.34-0.46)

Answer 24

306 BruxZir Anterior full-contour restorations placed; 96% of restorations received a rating of 5 at placement. Only 2 restorations were redone because of loose fit and light contacts; single crown (88%), bridges (10%) implant crowns (2%)

Answer 25

108 restorations were recalled at one year, no restorations exhibited chipping, no restorations required replacement; esthetics- excellent; excellent resistance to marginal discoloration, no wear observed on restorations or on opposing dentition

Answer 26

Over 670 pressed lithium disilicate restorations placed- cemented with self adhesive (87%) and esthetic resin (13%) cements; 381 restorations recalled- 68% at 5 years, 32% less than 5 years; molar crowns (46%) premolar crown (38%), anterior crowns (8%), inlays, onlays, bridges most restorations had no chipping or fracture, Fracture (required replacement) <2%, chipping 1.5%; esthetics- excellent, 6% of restorations slightly opaque; resistance to marginal discoloration- excellent, 2% slight graying at margins; 12 posterior crowns debonded

Answer 27

CeraSmart (GC America), Enamic (Vident- VITA), Lava Ultimate (3M) *higher translucency but lower flexural strength

Answer 28

BruxZir Now (Glidewell Laboratories) limited milling options

Answer 29

Color and optical properties of monolithic, shaded and layered milled restorations; wear of opposing teeth with full contour zirconia restorations; properties of milled resin ceramics vs zirconia vs silica based ceramics; longevity of lithium disilicate vs zirconia restorations

Answer 30

Reaction to applied force Elastic modulus, strength (yield, flexural, compressive, tensile) creep, ductility, malleability, hardness, fracture toughness

Answer 31

"young's modulus" "modulus of elasticity" a measure of rigidity ; a measure of a material's ability to resist elastic deformation; a measure of the stiffness of a material; the higher the elastic modulus, the less elastic and more stiff is the material

Answer 32

The measure of a material's ability to resist permanent (plastic) deformation; offset is the measure of plastic deformation in test or calculation (can be as little as 0.01%, typical is 0.2%, can be as much as 0.5% or more)

Answer 33

"Modulus of rupture"; a measure of a material's ability to resist fracture when a bending force is applied; a measure of both compressive (on top) and tensile (on bottom) strengths

Answer 34

the measure of a material's ability to resist being crushed or broken with the application of a pushing force

Answer 35

The measure of a material's ability to resist being separated from itself, or broken with the application of a pulling force

Answer 36

"creep modulus" a measure of the amount of plastic deformation of a material subjected to a compressive force over a given period of time

Answer 37

The measurement of a material's ability to be stretched up to its breaking point; the formula (final length - initial length) X100 a measurement of brittleness vs ductility

Answer 38

a solid material's ability to be plastically deformed under tensile forces without fracture; a solid material's ability to be stretched into a wire

Answer 39

a solid material's ability to be plastically deformed under compressive forces without fracture; a solid material's ability to form a thin sheet by hammering or rolling

Answer 40

Is so ductile that 1 oz can be stretched into a thin wire measuring only 5um in diameter and 50 miles in length; is so malleable that 1 oz can be beaten into a thin, continuous sheet measuring ~100 sq. ft.

Answer 41

The measure of a solid material's ability to resist plastic deformation on its surface when a compressive force is applied

Answer 42

the measure of a material's ability to resist fracture in the presence of an existing crack

Answer 43

"observation" dimensional change, dimensional stability, corrosion resistance, tarnish resistance

Answer 44

The volumetric change that can occur when the components of a material react to form a product

Answer 45

The volumetric change that can occur in a set material over time

Answer 46

Defined as the progressive destruction of a metal by a chemical or electrochemical reaction Galvanism is a corrosive process that occurs when an electrical current is generated between dissimilar metals in a solution of electrolytes (such as the mouth)

Answer 47

A thin layer of corrosion that can form on the surface of some metals; usually the result of an oxidation reaction with the metal; a tarnish layer can serve as a protection to the underlying metal (silver used to fight off infection)

Answer 48

An alloy of Hg (mercury) and one or more other metals; produced by mixing liquid Hg with solid particles of an alloy containing predominately Ag, Sn, and Cu; Zn, In, Pd, and Pt may also be present in small amounts

Answer 49

to blend, unite, combine, mix, merge or make a combination of 2 or more things; in metallurgy: to mix or alloy with Hg

Answer 50

to crush, grind or pound into small particles, to pulverize and comminute thoroughly

Answer 51

Once the amalgam alloy is freshly mixed (triturated or amalgamated) with liquid Hg, it has the plasticity that permits it to be conveniently packed or condensed into a prepared tooth cavity

Answer 52

the combination of solid metals vs amalgam alloy mixed with Hg Alloy is the solid part of amalgam filling- dental amalgam is the finished product

Answer 53

relatively easy to place, not overly technique sensitive, relatively long service life, inexpensive relative to other materials color, patient concerns over reported toxicity, concern about impact of amalgam disposal on wastewater and the environment

Answer 54

618- 907- possibly used in the first part of Tang Dynasty in China 1528- reportedly used in Germany 1800s- became the restorative material of choice due to its low cost, ease of application, strength and durability 1895- GV Black formulation published Circa 1900- first broad based research into dental amalgam (balanced composition) 1962- Dispersalloy introduced (addition of a spherical Ag- Cu eutectic particle to the lathe cut Ag3Snɣ particle) 1972- Tytin introduced (unicompositional spherical particles)

Answer 55

Ag3Sn ɣ small amount of Cu occasionally Zn; 10-20 year durability

Answer 56

also referred to as "crevice corrosion" likely due to Sn- Hg phase (Sn7-8Hg) ɣ2 [weakest phase in the hardened amalgam] acceptable characteristic of dental amalgam fillings at the time

Answer 57

From the greek "eutektos" meaning "easily melted" relating to or denoting a mixture of substances (in fixed proportions that melts and solidifies at a single temperature that is lower than the melting points of the separate constituents or of any other mixture of them

Answer 58

72% Ag 28% Cu Eutectic point- low point; Silver and copper alone have higher melting points

Answer 59

Low Cu, Hi Cu Admixed Regular (different Cu amounts) Lathe Cut- Low Cu Spherical- Hi Cu Admixed Unicompositional Lathe Cut- Same Cu Spherical- Same Cu Unicompositional - spherical

Answer 60

Ag3Sn; Ci (2-8wt%) irregular in shape- lathe cut

Answer 61

Ag3Sn; Cu (2-30wt%) lathe cut + Ag3Sn; Cu (20-40 wt%) spherical

Answer 62

Ag3Sn; Cu (29-30wt%) lathe cut + Ag3Sn; Cu (29-30wt%) spherical ex. dispersilode is this

Answer 63

Ag3Sn; Cu 13-20wt%) spherical

Answer 64

Ag- 40-60% (increase strength) Sn- 26-30% (increase regulates expansion and setting) Cu- 13-30% strength and hardness decrease corrosion and creep Zn <0.01% (Zn free) during manufacture; prevents oxidation In- 0-5% increase strength, decrease creep Pd 0-1% decreases tarnish and corrosion Pt 0-1% increases tensile and compressive strength

Answer 65

Included to help produce clean, sound ingots from which the lathe cut particles are made >0.01% can't be classified as Zn free Why is Zn bad? When moisture contamination occurs during amalgam placement, Zn will cause delayed expansion of the set amalgam

Answer 66

Ag3Sn (ɣ) Cu3Sn (ɛ) [small amounts] Cu6Sn5 (ƞ’) [small amounts] Ag4Sn (β) Ag-Cu (eutectic)

Answer 67

The amount of liquid Hg used to amalgamate the alloy particles is not sufficient to react with the particles completely more Hg is required to react with lathe cut alloy because of the increased surface area of the irregular, lathe cut shape

Answer 68

Ag3Sn +Hg --> Ag2Hg3 + Sn7-8Hg + (unreacted) Ag3Sn

Answer 69

Ag3Sn (ɣ) (27-35vol%) Ag2Hg3 (ɣ1) (54-56vol%) Sn7-8Hg (ɣ2) (11-13vol%) [weakest of all phases] Cu6Sn5 (ƞ’) (eta prime) (2-5vol%)

Answer 70

Ag3Sn + Ag-Cu +Hg --> Ag2Hg3 + Cu6Sn5 + (unreacted) Ag3Sn + (unreacted) Ag-Cu

Answer 71

Ag2Hg3 (ɣ1) Cu6Sn5 (ƞ’) Ag3Sn (ɣ) Ag-Cu eutectic

Answer 72

[Ag3Sn + Cu3Sn] + Hg | ---> Ag2Hg3 + Cu6Sn5 + (unreacted)[Ag3Sn + Cu3Sn]

Answer 73

Ag2Hg3 (ɣ1) Cu6Sn5 (ƞ’) Ag3Sn (ɣ) Cu3Sn (ɛ)

Answer 74

By adding the Ag- Cu eutectic to the alloy, the formation of the Sn7-8Hg phase was replaced by the Cu6Sn5 phase. This created a harder, more corrosion resistant amalgam

Answer 75

More condensable, easier to establish proximal contacts, less post operative senitivity vs better early strength, smoother surface, more easily adapted around retentive pins, requires less Hg

Answer 76

Most amalgams will achieve 40-60% strength within 1 hour Most amalgams will achieve 100% strength by hour 24

Answer 77

Mechanical (compressive strength, tensile strength, elastic modulus) Physical ( dimensional change, dimensional stability, corrosion resistance, tarnish resistance)

Answer 78

``` 1 hour (118 to 292 MPa) 7 days (387 to 516 MPa) ```

Answer 79

``` 15 min (3.8- 8.1 Mpa) 7 days- (43 to 56 MPa) ```

Answer 80

``` Amalgam (40-60 GPa) Composite Resin (5-20 GPa) ```

Answer 81

The "Creep Test" 7 day set amalgam cylinder, 37C, 36 MPa Compressive force, 104 hours, measured by the shortening of the specimen, ADA/FDI acceptable limit (1%), 0.05-0.45% is standard for Hi Cu Am; >1% creep indicates Sn7-8Hg is in the mix

Answer 82

Change in length of 8mm cylinder between 5 min and 24 hours after trituration; -1.9 to -8.8 um/cm of length (shrinkage); less shrinkage with admixed lathe cut alloys, more shrinkage with unicompositional spherical alloys --> increased PO sensitivity bonding agents --> decreased PO sensitivity

Answer 83

(4-methacryloyloxyethy trimellitate anhydride) 4META is most successful (for amalgam); 10 MPa shear bond strength to dentin; no true chemical adhesion, bond is produced by commingling of bonding agent with amalgam at interface; fracture resistance of bonded MOD amalgam is equal to that of bonded MOD composite resin and more than twice that of un-bonded MOD amalgam

Answer 84

Delayed expansion in Zn containing alloys resulting from moisture contamination; this contamination can occur anytime during mixing/ condensing; expansion begins 3-5 days after placement and may continue for months; can exceed 400 um/cm (4%) caused by the electrolysis of water by Zn which releases ZnO and H2 gas; H2 collects within the mass of the restoration, increasing internal pressure enough to cause the amalgam to creep and expand; can cause pain, typically 10-12 days after placement

Answer 85

Corrosion can occur on or within the amalgam through the interaction of dissimilar metals; corrosion can lead to increased porosity, reduced marginal integrity, loss of strength and the release of metallic products into the oral environment ; high Cu amalgam restorations are cathodic with respect to other metals within the mouth, such as Ay alloy; Galvanism can occur between these metals (a short term battery effect can be created; long term clinical significance is unknown); the accumulation of corrosion products in the micro-gap at the margin decreases microleakage over time ; consequently, post operative sensitivity can be more prolonged with high Cu amalgams

Answer 86

``` Ag2Hg3 (ɣ1) Ag3Sn (ɣ) Cu3Sn (ɛ) Cu6Sn5 (ƞ’) Sn7-8Hg (ɣ2) ``` (as go down, decrease corrosion resistance)

Answer 87

Tarnish occurs on the surface of the amalgam restoration as Ag is oxidized in a reaction with salivary chlorides and sulfides in the presence of O2. Although unsightly, it does not affect the mechanical properties of the amalgam

Answer 88

Dispensing and mixing, placing, condensing, carving, polishing

Answer 89

400 mg( 1 spill), 600 mg (2 spill), 800 mg (3 spills) 1200mg

Answer 90

The safety of amalgam restorations has been scrutinized since they were first introduced. To understand the possible side effects of dental amalgam, the differences between allergy and toxicity will be discussed

Answer 91

Allergic responses are an antigen- antibody reaction marked by itching, rash, difficulty breathing, swelling and other signs and symptoms; a small percentage of people may be allergic to mercury, just as a certain number of people are allergic to any number of metals; contact dermatitis or Coombs type IV hypersensitivity reactions are the most likely physiologic side effect to dental amalgam (these are experienced by <1% of the treated population); Lichenoid reaction (most common site: buccal mucosa immediately opposite a buccal amalgam; may occur on ventral surface of tongue adjacent to lingual amalgam; not very common- shows within a few days) To confirm suspicion of a true hypersensitivity to dental amalgam, the patient should be evaluated by an allergist

Answer 92

Fewer than 100 documentable reports of mercury allergy and toxicity attributable to dental amalgam have been published in the past 70 years in the scientific literature; the real hazard that may exist is the inhalation of mercury vapor during the mixing, placement and removal of dental amalgam personnel

Answer 93

The magnitude of vapor exposure for a patient with 8-10 amalgam restorations is between 1- 4.4 ug/day; the toxicity threshold for workers in the mercury industry is 350-500 ug/day

Answer 94

Mercury blood levels in one study indicated that the average blood level for patients with amalgam restorations was 0.7 ng/mL, compared to 0.3 ng/mL for subjects with no amalgam; a Swedish study demonstrated that one saltwater seafood meal/week elevated blood mercury levels from 2.3-5.1 ng/mL

Answer 95

15ug from food, 1 ug from air, 0.4 ug from water

Answer 96

Elemental Hg (released into air with fossil fuel combustion), inorganic Hg (found in the environment in combination with sulfur and oxygen), organic Hg (methylmercury found in soil and water; thimerosal, phenylmercuric acetate and other organic mercury compounds are synthesized and used as preservatives)

Answer 97

microorganisms in the soil and water can convert both elemental and inorganic mercury into methylmercury which can bio-accumulate in the food chain

Answer 98

Neurological disorders, fetal and infant developmental abnormalities, cerebral palsy in the developing fetus ALL forms of mercury can have toxic effects, however ORGANIC MERCURY is often the most insidious in its nature

Answer 99

Composite Resin components bisphenol A- BPA- estrogen mimicker aluminum- possible links to Alzheimer's Disease Barium- heavy metal

Answer 100

operatory should be well ventilated, all excess mercury including disposable capsules, should be collected and stored in well sealed containers, scrap and waste amalgam should be disposed of through reputable vendors, amalgam and mercury should not be incinerated or subject to heat sterilization, use disposable, single use pre-sealed capsules, only condense manually

Answer 101

There is no evidence to suggest that dental amalgam causes illness in the general population, several countries are phasing out amalgam because of ENVIRONMENTAL concerns. Denmark, Norway, and Sweden announced general bans in 2008-2009 on the use of mercury in any product including dental amalgam; Austria, Germany, Japan, and Canada have restricted the use of dental amalgam

Answer 102

Noble Metals (metals that retain their surface luster in dry air; metals that resist oxidation, tarnish and corrosion) base metals (metals that don't retain their surface luster in dry air; metals that oxidize, tarnish and corrode more easily)

Answer 103

Au – yellow, soft, malleable, ductile Pt – bluish white, tough, malleable, ductile Pd – white, improves quality of castings (as little as 5% profoundly whitens Au) Ir (Iridium) – grain refiner Rh (Rhodium) – grain refiner Ru (Ruthenium) – grain refiner Os (Osmium) – not used in dentistry

Answer 104

Used in small amounts; very high melting points; don't melt while casting; serve as nucleating centers for the molten metal as it cools, resulting in fine grain structures that improve the properties of the allow

Answer 105

Carat refers to Au content in units of 1/24 (18K is 75% gold); fineness refers to parts of Au per 1000 parts of alloy (18K is 750 fine); both systems are less useful now in dentistry

Answer 106

Type I: soft; simple inlays Type II: medium; complex inlays, onlays, single unit crowns Type III: hard; crowns and fixed dental prostheses Type IV: extra hard; partial denture frameworks

Answer 107

High Noble - ≥ 60% Noble and ≥ 40% Au Au-Ag-Pt Au-Cu-Ag-Pd-I Au-Cu-Ag-Pd-II ``` Noble - ≥ 25% Noble Au-Cu-Ag-Pd-III Au-Ag-Pd-In Pd-Cu-Ga Ag-Pd ```

Answer 108

Au-Pt-Pd yellow color, good corrosion resistance, lower strength Au-Pd excellent mechanical properties, good corrosion resistance Au-Pd-Ag high mechanical properties, easy to cast, lower density and cost Pd-Ag low density, low cost, good mechanical properties Pd-Cu high strength, easy to cast, low cost, form dark oxides

Answer 109

Indium, Tin, Gallium, Cobalt -enhance metal-ceramic bond, increase strength of alloy, lower the fusion temperature Iron- strengthens alloy Copper and Cobalt- produce dark oxide Silver- can cause “greening”

Answer 110

The alloy must have a melting temperature substantially higher (> 100C) than the firing temperature of the ceramic and the solders that may be used to join segments of the bridge. The alloy must form surface metal oxides that help create the bond between the ceramic and the metal. The alloy must have a compatible, but slightly higher, coefficient of thermal expansion than the ceramic. This tends to keep the ceramic in compression (where it is stronger) rather than in tension. The alloy must have adequate stiffness and strength to not permanently deform under masticatory forces. The alloy must have a high sag resistance ex. no distortion of the metal can occur during the firing of the ceramic. The alloy must create accurate castings, even with the high melting ranges of ceramo- metal alloys (more shrinkage upon cooling); preparation design is critical to allow for adequate thickness of restorative materials

Answer 111

ceramic over metal firing temperature --> room temperature The metal contracts more upon cooling, putting the ceramic in compression

Answer 112

Removable Partial Denture (RPD) Frameworks Copings for Ceramo-Metal (PFM) Restorations & Fixed Partial Denture (FPD) Frameworks Endodontic Instruments Orthodontic Wires & Brackets Pre-Formed Crowns Implants [Titanium]

Answer 113

``` Chromium(Cr) Cobalt(Co) Nickel (Ni)** Molybdenum(Mo) Tungsten(W) Carbon(C) Aluminum (Al) Iron(Fe) Manganese(Mn) Beryllium(Be)** Indium (In) Tin (Sn) Gallium(Ga) Copper (Cu) Silver (Ag) Niobium(Nb) Silicon(Si) ``` metalloid- having properties of both a metal and a non-metal

Answer 114

Be in both vapor and particulate form, is associated with contact dermatitis, chronic lung disease, lung carcinoma, and osteosarcoma. Ni is an allergen. Sensitivity to Ni is 5-10x higher for females than males; 5-8% of females show sensitivity to Ni

Answer 115

Cr- tarnish resistance, >29% ---> increase brittle CO- increase elastic modulus, strength and hardness, increase strength of porcelain/metal bond Ni- increase elastic modulus, strength and hardness (Co and Ni generally interchangeable) Mo- increase strength W- increase strength C- increase hardness (typically only <0.1-~0.5wt%) Exact amount of C is critical! Al- forms Ni3Al (Nickle Aluminide)--> properties similar to ceramic and metal tensile and yield strength Fe- increase strength Mn- increase fluidity and castability Be- increase improves castability by decrease the alloy's melting temp ~ 100C and decrease surface tension of the molten alloy, also increase strength of porcelain/ metal bond In- increase strength, decrease fusion temperature, increase strength of porcelain/metal bond Sn- increase strength, decrease fusion temperature, increase strength of procelain/metal bond Ga- increase strength, decrease fusion temperature, increase strength of porcelain/ metal bond Cu- can prodcue a dark oxide Ag- can cause "greening" Nb- similar to Ti in it's properties Si- enhances fluidity and castability

Answer 116

``` Co-Cr (Vitalium) Co: ~ 63 wt% Cr: 30 wt%: Mo: 5 wt% Fe: 1 wt% ``` ``` Ni-Cr (Ticonium) Ni: ~ 66 wt% Cr: 17 wt%: Mo: 5 wt% Al: 5 wt% Be: 1 wt% Mn: 5 wt% ``` ``` Ni-Cr c Be (Rexillium III) Ni: ~ 77 wt% Cr: 13 wt%: Mo: 5.5 wt% Al: 2.5 wt% Be: 1.9 wt% ``` ``` Ni-Cr s Be Ni: ~ 64 wt% Cr: 22 wt%: Mo: 9 wt% Nb: 3.5 wt% ``` ``` Co-Cr Co: 62 wt% Cr: 26 wt% Mo: 6 wt% W: 5 wt% Si: 1 wt% ``` ``` Co-Cr c Noble Metal Co: ~ 62 wt% Cr: 20 wt% Mo: 4 wt% Al: 2 wt% Mn: 4 wt% Au: 2 wt% Ga: 6 wt ```

Answer 117

Co-Cr (Vitallium) – RPD Frameworks Ni-Cr (Ticonium) – RPD Frameworks Ni-Cr (Rexillium III) with Be – PFM Metal Ni-Cr without Be – PFM Metal Co-Cr – PFM Metal Co-Cr with Noble Metal – Used for High Expansion Porcelain

Answer 118

Have higher hardness values than noble metal alloys; have a higher elastic modulus than noble metal alloys; are more difficult to cast and solder than noble metal alloys; are more technique sensitive than noble metal alloys; undergo more solidification shrinkage than noble metal alloys

Answer 119

Most melt between 1400-1500 C, Ni-Cr-Be melts at 1275C, Types I to IV Au alloys melt between 800-1050C

Answer 120

Between 7-8g/cm3, half the density of Au alloys, lower density can be an advantage for larger maxillary appliances, more difficult to cast!

Answer 121

Dependent upon: Electrolytic media (the solution or salivary composition), alloy composition, alloy microstructure, surface state of the alloy (usually a different composition than the bulk of the alloy), corrosion coupled with wear: 3x Ni ions released

Answer 122

Elastic modulus of base metal alloys is twice that of Au alloys; Greater rigidity allows the fabrication of restorations with reduced dimensions

Answer 123

Base metals are harder than Au alloys; polishing techniques are more complicated

Answer 124

Minimum of 415 MPa needed to maintain RPD clasp integrity

Answer 125

Base metal alloys are all greater than 800 MPa

Answer 126

Wide variability among base metal alloys; too high --> the RPD clasp can't maintain it's shape Too low --> the RPD clasp is too brittle and breaks

Answer 127

Alloy Type (RPD);% Elongation Au Alloy (Hardened) 5-7 Co-Cr (Vitallium) 1.5 Ni-Cr (Ticonium) 2.4

Answer 128

Au-Pt-Pd (Noble) 3-10 Co-Cr (Base) 6-15 Ni-Cr (Base) 8-20

Answer 129

Material; Yield Strength (0.2 % offset) MPa Au-Pt-Pd (Noble) 480-510 Co-Cr (Base) 644 Ni-Cr (Base) 710

Answer 130

Material; Elastic Modulus (GPa) ``` Co-Cr alloy 218 Au Alloy (Type IV) 99 Feldspathic Porcelain69 Enamel 84 Dentin 18 Composite Resin 17 ```

Answer 131

Have higher melting ranges than cast Au alloy types I through iV 1150 C to 1500C for base metal alloys; 800C to 1050C for cast Au alloys Have lower densities than cast Au alloy types I through IV; ~1/2 that (7-8g/cm3) of cast Au alloys; can create difficulties with casting

Answer 132

In general, RPD base metal alloys, such as Vitallium and Ticonium, contain more C than base metal alloys used in PFM fabrication. RPD base metal alloys, such as Vitallium and Ticonium, are harder, stronger, and stiffer than base metal alloys used in PFM fabrication.

Answer 133

Pre- oxidation- relieves internal stresses, forms an outside layer of metal oxides with which the porcelain forms a chemical bond, this process is unique and specific to each of the metal alloys; sometimes referred to as "Degassing"

Answer 134

Wide range of surgical applications "surgical Vitallium", bone plates, surgical screws, fracture repair appliances of various sizes and shapes, can be implanted directly into bone for long periods without harmful reactions, seems to be bio-inert with no initiation of an inflammatory response

Answer 135

a black or reddish-brown mineral consisting of titanium dioxide (TiO2), typically occurring as needle- like crystals; the most common natural form of titanium dioxide (TiO2)

Answer 136

Ninth most abundant element in the earth's crust; fourth most abundant structural metal; commercial production began in 1950s; worldwide titanium production is now over 25,000 tons, annually; high strength/density ratio; excellent corrosion resistance

Answer 137

Aerospace and defense industry (aircraft engines, aircraft frames, missiles, spacecraft), deep sea marine application, navy ship components, automotive industry, recreation/sport equipment, biomedical devices

Answer 138

Resistant to electrochemical degradation, benign biological responses, relatively light weight and low density (4.4-4.5g/cm3) [make it difficult to cast], high melting point (CP Ti-1700C, Ti Alloys (+/- 1350C), rapidly passivates (10^-9sec) by forming a very stable and protective oxide layer on the surface

Answer 139

To make a metal or other material unreactive by altering the surface layer, or coating the surface with a thin inert layer; To coat a material with an inert substance to protect it from contamination

Answer 140

Variable Tensile Strength (240-890 Mpa) Variable Yield Strength (170-830 Mpa) 0.2% Offset High Fracture Toughness Low Thermal Expansion Coefficient Low Elastic Modulus (103-114 Gpa)- somewhat elastic Elongation Percent (10-20%) quite ductile Alloying has significant effect on mechanical properties – most common alloy for implants is Ti-6Al-4V

Answer 141

CP Grade I CP Grade II CP Grade III CP Grade IV Each grade varies according to oxygen (0.18-0.40 wt%) and iron (0.20-0.50 wt%) content These slight concentration differences have a profound effect on the physical and mechanical properties of the titanium

Answer 142

The property of some elements that can exist in 2 or more different forms, in the same physical state. These different different forms are known as allotropes; Titanium exhibits allotropism

Answer 143

α Phase – Hexagonal close-packed (HCP) crystal lattice β Phase – Forms at temperatures above 883˚ C, body-centered cubic (BCC) form Alloying Ti with other metals preferentially stabilizes either the α or the β phase to influence the properties of the Ti alloy

Answer 144

α- Al is an α phase stabilizer; good weldability, excellent strength characteristics, difficult to form or work at room temp β- Vanadium, copper and palladium are β phase stabilizers; malleable at room temp, useful in orthodontics α+β- good strength properties; difficult to weld

Answer 145

The mechanical properties of cast CP Ti are similar to those of types III and IV gold alloys The mechanical properties of cast Ti- 6Al- 4V and Ti-15V are similar to those of Ni-Cr and Co-Cr alloys

Answer 146

``` Ti-6Al-4V Ti-15V Ti-20Cu Ti-30Pd Ti-Co Ti-Cu Ti-Cu-Ni Ti-6Al-4Nb ```

Answer 147

Implants (machined), Crown (computer aided machining; electric discharge machining or spark erosion cast), FDP Frameworks (Computer Aided Machining (CAM), electrical discharge machining or spark erosion cast), RPD Frameworks (computer aided machining (CAM), electrical discharge machining or spark erosion cast)

Answer 148

Machined from billets of Titanium; CP Ti, Ti-6Al-4V A billet is a length of metal that has a round or square cross section. A billet is created directly via continuous casting or extrusion, or indirectly via hot rolling an ingot (large rough casting) or blood (an ingot that has been rolled into a smaller cross sectional area)

Answer 149

Abrasive machining (CAM) of titanium is slow and inefficient; spark erosion technology is expensive and technique sensitive; currently, technologies to cast, machine, weld and/or veneer titanium with porcelain are very technique sensitive and expensive Consequently, our focus on titanium will be in the area of implantology. The passivating oxide on the implant surface permits close apposition of physiological fluids, proteins, and hard/soft tissues to the metal surface. The process whereby living tissue and an implant become structurally and functionally connected is called osseointegration.

Answer 150

Grit Blasted (metal-oxide, hydroxyapatite particles) plasma sprayed with Ti, coated with hydroxyapatite

Answer 151

Beaten out or shaped by hammering, "cold worked", the work done to the alloy is usually at a temperature significantly below the solidus line; worked and adapted into prefabricated forms for use in dental applications (precision attachments, backings for artificial teeth, wire in various cross sectional shapes)

Answer 152

Can be soldered to an existing RPD framework. They can be cast to a new RPD framework.

Answer 153

Wrought forms have a fibrous microstructure that results from the cold work applied during the operations that shapes the metal. This cold work increases both tensile strength and hardness. Prolonged heating of wrought forms can cause them to recrystallize and develop a grain structure similar to their cast form. Recrystallization adversely affects the mechanical properties. Severe recrystallization can cause wrought forms to become brittle. Heating operations must be minimized when working with wrought forms.

Answer 154

``` High Noble Pt-Au-Pd Au-Pt-Pd Au-Pt-Cu-Ag Au-Pt-Ag-Cu Au-Ag-Cu-Pd ``` Noble- Pd-Ag-Cu Titanium Ni-Ti β-Ti Stainless Steel Martensitic(Cr-Co) Ferritic (Cr-Co) Cr Austenitic (Cr-Ni)

Answer 155

Clasping wires for removable prostheses Not commonly used due to high cost

Answer 156

β-Ti 78%Ti-11.5%Mo-6%Zr-4.5%Sn This alloy composition stabilizes the β phase at 37° C Less force than stainless steel wires Low elastic modulus High springback* (max elastic deflection) Low yield strength Good ductility, weldability & corrosion resistance ``` Ni-Ti – “Nitinol” 55%Ni-45%Ti High Resiliency Called “Shape Memory Alloy”or “Thermal Memory” Wire can be plastically deformed below the TTR (temperature transition range), then when warmed above the TTR will assume its original shape Lowest elastic modulus Highest springback* Lowest yield strength ```

Answer 157

Ni-Ti – “Nitinol” 50-60%Ni-40-50%Ti Co, up to 2%, substituted for Ni will lower TTR 2-3X the Memory of stainless steel Unique shape memory Super-elasticity Most bio-compatible of the super-elastic alloys Excellent corrosion resistance Resists torsional (twisting) fractures Can be strained up to 8% with full recovery of shape (1% for stainless steel)

Answer 158

6% Strain ; Several 100 Cycles 2% Strain; 10^5 Cycles 1% Strain; 10^5 Cycles

Answer 159

Austenite Phase (Parent Phase); Body-Centered Cubic Lattice (BCC) Above 100° C ----(cooling)-----> 37° C Martensitic Phase (Daughter Phase) Hexagonal Close-Packed Crystal Lattice (HCP) super elasticity Austenite(BCC)--(cooling)---> martensite (HCP, twined HCP) ---(Deformation)--> Martensite (HCP; De-twined HCP)----(heating)--> Austenite

Answer 160

Iron alloyed with carbon; carbon gives steel strength, but also makes it more brittle; steel is not corrosion resistant, steel can also be alloyed with varying amounts of Ni*,Cr, Mo, B, Ti, V, W, Co & Nb

Answer 161

A steel that contains a minimum of ~11% Cr; chromium passivates the surface via the formation of a strongly adherent Cr2O3 layer; Stainless steels are much more corrosion resistant than high carbon steels; stainless steels are not as hard as high carbon steels

Answer 162

martensitic, ferretic, austenitic

Answer 163

Corrosion resistant, hardenable by heat treatment, magnetic, high hardness, high strength, high wear resistance, 11.5-18% Cr, No Ni*, is a very brittle crystalline structure of C and Fe that is the main constituent of hardened steel. Named after the German metallurgist, Adolf Martens (1850-1914)

Answer 164

More corrosion resistant than Martensitic, but less than Austenitic; non hardenable by either heat or work, can be cold-worked, can be softened by annealing; magnetic, 10-20% Cr, no Ni*, Ferrite (Fe2O3) or ferric oxide, or rust, is a type of ceramic compound; name is a derivation of ferrous or ferric, "having to do with iron"

Answer 165

Most corrosion resistant; added corrosion resistance is from the formation of a solid solution of Cr-Ni-Fe; can't be hardened by heat treatment, can be hardened by cold-working; non- magnetic (~10% Cr, ~8% Ni) Gamma phase iron(ɣ-Fe) Named after Sir William Chandler Roberts-Austen (1843-1902)

Answer 166

Martensitic (hardenable by heat, corrosion resistant) Ferritic (not hardenable, more corrosion resistant) Austenitic (hardenable by heat or cold work, most corrosion resistant)

Answer 167

Ferritic Steel (Cr-Co)- dental instruments, some dental equipment parts Martensitic steel (Cr-Co) Dental instruments, ortho appliances Austenitic Steel ( Cr- Ni*)- stayplate/flipper claps, ortho wires The last 2 are the most common wrought wires used in dentistry today

Answer 168

Objectives of cementation or luting are to help maintain restoration in place, maintain integrity of remaining tooth structure

Answer 169

Retention is achieved by: friction, adhesive joint, the cement, the restoration, or both mechanisms

Answer 170

an effective interfacial seal depends on the ability of the cement to fill the irregularities between the tooth and the restoration and to resist the oral environment short and long term Strong bond between the luting agent and dental substrates is also important because it can prevent infiltration of bacteria and fluids that can cause caries and sensitivity to the patient

Answer 171

Cast alloys, ceramics, indirect (lab) composites, amalgam, fiber posts, repair of composite, ceramic, and ceramic- metal restorations

Answer 172

According to the length of time that they are expected to stay in function provisional (low strength and easy handling, no irritate pulp) such as Zinc oxide and non-eugenol cements and calcium hydroxide pastes Definitive (remain in function for the longest time possible, must have sufficient properties)

Answer 173

Acid based reaction: GI, RMG, zinc oxide- eugenol, zinc polycarboxylate, and zinc phosphate setting by polymerization: resin cements, compomers, and self- adhesive cements

Answer 174

zinc polycarboxylate, Gi, RMG, Self adhesive resin cements

Answer 175

"preservation of a healthy set of natural teeth for each patient should be the objective of every dentist"; all work in the health field is aimed basically at conservation of the human body and it's function

Answer 176

Adhesives- dentin morphology and physiology, adhesive systems, adhesive dentistry (case reports)

Answer 177

Micromechanical retention (dentin, adhesive resin tags, composite resin restoratives)

Answer 178

Finding in 1955 that acid etching of the enamel increases the bond strength of resin to enamel; The practice of bonding to enamel has become a routine procedure in many fields of dentistry

Answer 179

surface not even- better mechanical retention

Answer 180

Approximately 1/2 of all restorations placed in general dental practice are done to replace a defective or failed restoration; the reasons that restorations are replaced may be divided into 3 major categories: clinical factors (technique), material properties (will surface withstand stress ex. bruxism), and patient factors (want a white filling)

Answer 181

morphology, physiology, smear layer, saliva, structure of tubules

Answer 182

Dentinal tubule (large)--> peritubular dentin (around tubule) --> intertubular dentin (around peritubular)

Answer 183

50% mineralized apatite crystals, 20% water, 30% organic matrix (collagen fibrils)

Answer 184

water content varies from superficial to deep dentin (diameter and number of tubules increase near pulp, 20,000 tubules/mm2 at DEJ vs 45,000 tubules/mm2 close to pulp) superficial dentin hybrid layer is a form of intertubular resin infiltration while deep dentin hybrid layers are mainly composed of resin tag formation (an example of intratubular permeation; peritubular dentin matrix below the depth of acid etching)

Answer 185

hypermineralized (like a scar- protecting pulp), tubules occluded with CaPO4 crystals, acid resistant (etching won't occur easily- must use phosphoric acid with higher %)

Answer 186

collagen fibers susceptible to collapse upon over- drying keep dentin moist when restoring or else collagen network will collapse- cross linking will not occur- keep dentin moist for good bonding Changes in the matrix when dentin is decalcified with phosphoric acid 1. mineralized dentin matrix 2. demineralized dentin matrix filled with water (plasticized) 3. collapsed stiffened air dried demineralized dentin matrix 4. demineralized dentin matrix stiffened by organic solvents in air

Answer 187

producing bubbles- PG won't infiltrate tubules properly *look at slide 25

Answer 188

0.5-2um thick, can't be removed with rinsing, composed of bacteria, saliva, blood cells, denatured collagen

Answer 189

A thing made by combining 2 different elements (a mixture) ex. a car with gasoline engine and an electric motor each of which propel it

Answer 190

"the structure formed in hard dental tissues by demineralization of the surface and subsurface, followed by infiltration of monomers and subsequent polymerization" remove smear layer, add primer (all adhesives have 3 types of solvents acetone, ethanol, water) - adhesive (monomer- any polymer that is liquid; once cured it’s a polymer) solvent helps primer penetrate; air dry; apply adhesive, then cure (hybrid layer is formed) different adhesives- have dif. solvents

Answer 191

"understanding the anatomy and physiology of dentin has been critical to the development of high- performance dentin bonding systems" utilize A/Phys of dentin for max bond strength; resin monomers infiltrating demineralized dentin (denting exposed to phosphoric acid- resin tag open use morphology of substrate to your advantage)

Answer 192

primer (allows penetration; hydrophilic monomer (HEMA), water soluble solvent- water, acetone, ethanol) adhesive (unfilled or lightly filled resin [Bis-GMA])

Answer 193

*** slide 34 Conditioner (etchant), primer, adhesive 4th generation-1. remove smear layer (phosphoric acid etching), 2.primer, 3.adhesive 5th generation[golden standard]- 1. remove smear layer (phosphoric acid etching), 2. combined primer and adhesive resin; resin tags are longer 6th generation- * improves over time 1. dissolve smear layer [ no phosphoric acid, primer dissolves the smear layer], 2.self etching primer, 3.adhesive

Answer 194

4th- primer and adhesive are in separate bottles, more steps, slightly more predictable 5th- primer and adhesive are mixed together in one bottle, less steps, less predictable, more susceptible to differences in wetness

Answer 195

newer generation; significant difference in technique, user-friendly (no more phosphoric acid etching); acidic monomer dissolves smear layer and primes dentin simultaneously; one step or two step system

Answer 196

Higher bond strength in deep dentin than 4th and 5th generation adhesives [ bond strength when closer to pulp is usually weak, this makes it stronger], bonds well to CUT enamel [restoration/prep], not as well to uncut enamel [ braces], resin tag formation not as pronounced, doesn't seem to affect bond strength, 2 step self etching adhesives more predictable than one step products

Answer 197

Dissolve smear layer, self etching primer and adhesive all in one bottle

Answer 198

• Scotchbond Mul'Purpose Plus (3M ESPE) – Ethanol, Water; Unfilled • AllNBond 2 (Bisco) – Acetone, Ethanol; Unfilled • Op'bond/Op'bond FL (SDS/Kerr) – Ethanol/Water; Filled * adhesive has filler or no filler- add particles to make it stronger (improve mechanical properties)

Answer 199

• Prime&Bond NT and NT Dual Cure (Dentsply/ Caulk) – Acetone, Ethanol, Filled • Op'bond Solo Plus (SDS/Kerr) *gold standard* – Ethanol, Filled • Single Bond Plus (3M ESPE) – Ethanol/Water; Unfilled

Answer 200

*solvent is always water • Clearfil SE Bond (Kuraray) – Water; 10% Filled; Light-Cured * Adper Prompt L-Pop (3M ESPE) – Water; 2% Filled, Light-Cured * Clearfil Liner Bond 2V (Kuraray) – Water; 10% Filled, Dual-cured * OneNUp Bond F (fluroide) Plus (Tokuyama) – Water; 10% Filled, Light-cured *make sure material compatible with fluoride

Answer 201

iBond (Heraeus Kulzer)- unfilled, light cured G-bond (GC Corp.)- 5% filled, light-cured and more to come..

Answer 202

want them to stay at same value or increase in value; SE and SB really good? look at slide 46/47

Answer 203

4th (primer, adhesive, etch) 5th (one bottle, etch), 6th (etch-primer, adhesive), 7th (one bottle)

Answer 204

3 steps (etching, priming, and bonding) vs 2 steps (etching and primer and bond mixed in one bottle) etching is 30-40% phosphoric acid (conditioners) to demineralized tooth structure primers are hydrophilic monomers, oligomers, or polymers, usually carried in a solvent (acetone, ethanol, or water)

Answer 205

two step system with a hydrophobic bonding resin in a separate bottle; all in one system; ester monomers with grafted carboxylic or phosphate acid groups dissolved in water

Answer 206

most bonding agents are light-cured and contain an activator such as camphorquinone and an organic amine; dual-cured bonding agents include a catalyst to promote self-curing; some bonding agents contain: nanofiller, fluoride (glass ionomers), antimicrobial ingredients, or desensitizers (glutaraldehyde_

Answer 207

by far, the most important mechanical property is bond strength among in- vitro research

Answer 208

solvents and monomers in bonding agents are usually skin irritants (HEMA can produce local and systemic reactions to dentists and dental assistants (gloves, mask, high speed suction, keep bottles closed and unit dose system)

Answer 209

longevity of bond in general practice may be only 40% of that achieved in clinical trials because don't follow instructions, clinical studies are highly controlled; 95% of secondary caries associated with resin composites is in the interproximal areas (hard to clean [patient], clinician [ don't use all tools needed, don't do increments of 2 mm- tend to fail]; clinical performance can be evaluated by (postoperative sensitivity, interfacial staining, secondary caries, retention or fracture followed for 18 months)

Answer 210

bonding to enamel occurs by micromechanical* retention after etching bonding penetrates the etched surface and becomes locked into place after polymerization occurs

Answer 211

50% mineralized apatite crystals, 20% water, 30% organic matrix (collagen fibrils)

Answer 212

primers (hydrophilic components such as HEMA [wet dentin and penetrate its structure]); total etch or etch and rinse systems (phosphoric acid removes the mineral creating microsporosites within the collagen network); after etching step, the dentin contains about 50% unfilled space and about 20% remaining water, after acid is rinsed, drying of dentin must be done cautiously

Answer 213

Dehydration of the dentin outer surface will cause that the remaining collagen scaffold to collapse onto itself then the collagen mesh will exclude the penetration of primer and bonding will fail. excess of moisture tends to dilute the primer and interfere with resin interpenetration; ideal dentin moisture levels varies according to the solvent present in the adhesive

Answer 214

resin composite (RC), hybridization, hybrid layer (HL) resin tags (RT)

Answer 215

the structure formed in hard dental tissue by demineralized of the surface and subsurface followed by infiltration of monomers and subsequent polymerization

Answer 216

durability is one of the most challenging problems of adhesive/dentin bonds

Answer 217

shade match after vital bleaching, conservative preparation, bonded indirect resin FPD [splint- acrylic- gets hard and cement- cemented with resin cement and adhesive ]

Answer 218

8 year old male, basketball incident in which patient fell to floor, fracturing #8,9; patient had been to one dentist prior to arrival at office, dentist placed dycal and instructed patient to leave teeth alone [calcium hydroxide deep base- due to exposure of pulp want to create dentin bridge] diagnostic aids- periapical x-ray revealed large pulp chambers, no apparent periapical pathology at this time, apices were open and still developing, father had saved fractured pieces 8,9 Pumice teeth, clean, and gently dry; applied self etching primer, dry to remove solvent (water), adhesive placed and gently dried, light cured for 10 sec, flowable composite placed on fractured surface of tooth (use flowable because mechanical properties in anteriors are not as high), also placed on lingual surface, primer and adhesive placed on surface of fractured piece and light cured prior to placement, 8 was re attached and light cured, flowable composite placed on #9, adhesive placed on fractured piece and tried in, #9 bonded to place, acid etched enamel surfaces, additional composite placed, bonding complete, prior to contouring, contoured facial surfaces and polished with Sof- Lex,

Answer 219

A strong, durable, and bonded interface with enamel and dentin provides benefits. protects the interface of the restorations against penetration of bacteria and fluids that can cause recurrent or secondary caries. Reduces the need of retentive areas in the prep that would required removal of sound tooth structure. Sometimes strengthen the remaining tooth structure. it is very difficult to achieve chemical bonding between tooth structure and a restorative material because of the complex composition of some substrates such as dentin, presence of contaminants and water. in daily practice, adhesion is accomplished by micromechanical interlocking between the adhesive and tooth substrate. Aspects to create an adhesive joint: cleanliness of the surface (biofilm, debris, saliva) and smear layer These contaminants will reduce the surface energy of the bonding substrate and its wettability

Answer 220

generally speaking, anything inserted into the mandible or maxilla designed to take the place of a tooth; have been in use at least 2,300 years; modern implants usually take the form of a self tapping titanium screw or post; millions of dental implants are placed annually worldwide [better than bridgework and crowns]

Answer 221

most common, sits inside bone (post, screws) crew post into bone- build restoration on top; typical system; Have blade, screw, cylinder: blade not very effective; will mostly see screws (modern- thread into bone) vs cylinder

Answer 222

much rarer, were used in cases of atrophic bone/ sit atop bone sit like a saddle on top; rarer because mass recession around implant- high failure rate

Answer 223

quite uncommon, higher failure rates. post transverses the entire mandible, not used on the maxilla. disadvantage: operation to place is quite brutal

Answer 224

alveolar process: ridge on surface of mandible/maxilla where teeth are basal bone: bone underlying the alveolar process alveolar bone proper and supporting alveolar bone

Answer 225

compact bone (cribiform plate, lamina dura) cribiform- plate with a lot of bones; radio opaque that surrounds tooth; lines tooth socket

Answer 226

both compact and trabecular bone. cortical plates (compact bone component), central spongiosa (trabecular bone component) surrounds both sides, supports plates

Answer 227

loading via mastication critical for maintaining bone density; loss of alveolar bone in edentulous patients [ no loading= no alveolar ridge, only basal bone] ; patient selection/site preparation critical for high success rate of dental implants - must build up bone to place implant; may have other sources that impair healing ex. Diabetes ; if can’t heal things properly or quickly will be a major challenge Success rates are high PROVIDED THAT patients are selected well- can’t be patients that won’t change their lifestyles ex. Smokers, diabetics that don’t manage diabetes, etc.

Answer 228

deposition of bone in close apposition to implant surface (really by oxide layer); clearly a highly desirable process, mediated by mesenchymal progenitor cells; provides mechanical stability of implant and tight seal [preventing inflammation, want good healing] Vs biointegration (direct apposition to ceramic- bone can attach directly to ceramic surface- ceramic and titanium becomes weak spot) Oxide layer- increases biocompatibility – Will always see a gap between bone and titanium oxide Survive repeated cyclical loading is the main goal of teeth Implant anchored well to bone

Answer 229

wound healing (space management); extraction of tooth= hole; hole fills with a clot, which is then converted to a highly cellular granulation tissue; epithelial invasion vs bone regeneration; osteoblast differentiation and bone deposition (osseointegration) Wound- void in tissue Wound managing- restoring integrity of compartments Blood is key component of wound healing- managing compartments Osteoblasts- build bone/mesenchymal; osteoclasts- break down/hematopoietic; together make mature bone Don’t want epithelial cells to prevent this process of bone formation- things tend to turn into what they are next to (bone growth factors are released) DON’T want epithelial ingrowth- will never get CT forming (“preparing integrity of compartment” - but don’t want it” GT- granulation tissue (want it to give rise to tissue that you want -->new bone) 9 week- almost full closure- osseointegration is occurring

Answer 230

Stro-1, osteoblast- progenitor associated marker, F4/80, macrophage marker, TGFB1, growth factor, Osteopontin, non collagenous matrix protein Initial inflammation must resolve- drives osseointegration

Answer 231

Formation of fibrous tissue (collagen) around implant; bad news for mechanical anchoring; can result from peri-implantitis brought on by a number of factors, but often problems/delays in osseointegration= microbial infiltration or poor stability after placement If inflammation does NOT resolve- Fibrous collagenous sac around implant- bone will not lay down; will be lose and will come out; not mechanically stable

Answer 232

tensile, compressive, and shear forces all brought to bear on implants; up to 1250N reported[ 1 N = force required to move 1 kilo at 1m/s^2] due to forces involved: material properties and integration of implants are critical bite force especially strong by hinge

Answer 233

bone must experience strain or it will resorb; ceramics tend to be quite stiff and don't transfer adequate strain to surrounding bone, resulting in "stress shielding" elastic modulus: too high= lower transfer of force to bone= lower bone loading

Answer 234

Titanium somewhat more elastic and transfers some strain to surrounding bone thus an implant material must be structurally sound but also must have mechanical properties which are physiologically compatible

Answer 235

bone is strongest when compressed, weaker under tensile forces, and weakest when subjected to shear The bone- implant interface therefore is critical when considering mechanical loading of implants bone in apposition to smooth implants is subjected to almost total shear when the implant is loaded and less surface area for attachment

Answer 236

Adding texture (ex threads) engage bone in compression where it is strongest; interlocking also provides much better transfer of load to bone (less resorption) and increased surface area for attachment

Answer 237

alterations in the length and width of implants also have implications for implant loading increasing length: increase surface area of attachment= decreased stress on bone. Minimal advantage however as most force transfer happens at the upper part of an osseointegration implant (also anatomy and heating- loner it is, the more heating) increasing width: increased surface area for attachment= decreased stress on bone. Implant stiffness increases, leading to stress shielding of bone There is an optimal range for these parameters. Implants can be too long/short, or too narrow/wide

Answer 238

Titanium is the most common material employed in dental implants: CP Ti or Ti-6Al-4V alloy has a number of excellent properties: elastic modulus lower (flexes more, avoid stress shielding)than ceramic but compared to rubber band (higher) ; strength, immune inert (non immunogenic), low corrosion (passivation- continual presence of a passive oxide layer), biocompatible (non- toxic) Ti can be simply modified: alterations in oxide layer (oxide layer is mainly what biological systems interact with [can make thicker and improve compatibility] ), coatings (biomemtic or ceramic), roughening/etching (grit blasting or acid etching) surface modification generally has the aim of either enhancing osseointegration by osteoblast differentiation/migration, improving the mechanical interlocking with bone tissue, providing better loading characteristics (ex. threads) optimal surface still unclear

Answer 239

machined, Ti Grit Blasted HF Etched, Tri- Calcium Phosphate Sputter Coated (smooth surface --> roughened--> coated) alteration of surface topography can have an impact on the biology of attached cells (smoother surfaces have rounder cells; rougher surfaces have different cells)

Answer 240

generally refers to increasing oxide layer; TiO2 forms the stable oxide layer, Oxide layer generally biologically favorable (protein absorption), modifications such as hydroxylation increase hydrophilicity (wettability); anodization used to increase oxide layer thickness increase affinity to blood which increases management

Answer 241

many coatings are also applied to implants; ceramic and glass coating (hydroxyapatite/tricalcium phosphate/bioglass)- bioactive, although only as strong as the metal- ceramic interface ceramic coating is the weak point [metal- ceramic interface, bone-ceramic interface] coating with short peptide sequences to increase cell attachment: integrins, RGD cell attachment sequences, collagen, fibrin coating with growth factors associated with wound healing such as TGFB1, FGF-2, VEGF, PDGF. [doesn't work; optimal healing comes with exposure of all of these at the same time but not just one]

Answer 242

endosseous implants have a 7 year survival rate of around 95% (because of soft tissue); this is however due to careful patient selection. die to the requirements for rapid osseointegration, patient selection is critical; must have good bone around site to anchor implant during loading (many edentulous patients have atrophied bone), must not (challenge) be compromised in terms of bone healing (diabetes, immune compromised patients can pose problems depending on how compliant they are), implants have a very high success rate, the next clinical challenge is developing implants which can be placed in complex or difficult clinical situations

Answer 243

tissue engineering is a discipline which seeks to encourage the restoration of function and structure to a pre-injury state; bioactive materials (materials which are designed to drive repair/regeneration through the use of bioactive factors) traditionally 3 components in tissue engineering: relevant cell source, biomaterial or scaffold[ what you implant cells in], bioactive component to drive cell responses

Answer 244

implanted material derived from the same individual as the implant is to be delivered into

Answer 245

implanted material derived from another individual of the same species

Answer 246

implanted material derived from another species

Answer 247

implanted material is not derived from a living source or is "synthetic" very broad category

Answer 248

population of mesenchymal progenitors resident in the dental pulp, derive from the neural crest; huge topic in dental pulp biology (focus of both cellular and a cellular approach to tissue engineering); can theoretically differentiate to regenerate vasculature, mineralized tissue, soft tissue, or possibly even nerves; represents a capacity of the tooth for self repair ( or other tissues- SHED banking) Steady state turnover --> Quiescent niches --> trauma response (by stimulatory signals) --> Reparative dentine

Answer 249

addition material containing cells vs application of materials to existing tissues; tissues need cells to regenerate, but many contain cells containing the necessary cells (ex. a capacity to self repair) there are advantages and disadvantages to each soft tissue: periodontal ligament, dental pulp, oral mucosa, skin hard tissue: bone, dentin, cementum Ex. root canal OR cells + scaffold OR scaffold +native tissue If want to regenerate pulp; needs progenitor cells (cell source) Acellular approach- leave native tissue and then add bioactive material

Answer 250

practical difficulties (relatively low cell number- possibly around 1% of cells) practical difficulties (lack of single specific marker to ID cells; generally a panel used) Gold standard( 1. population doubling over long periods in culture 2. multipotency: ability to differentiate in various lineages ( adipose, endothelial, chondro- osteo-) DPPCs are adherent cells ex. they attach to tissue culture plastic, but so are many other cells found in the pulp They typically express high levels of the α5β1 integrin receptor, which binds fibronectin: fibronectin adhesion isolation adherent--> tissue culture non-adherent --> disposal Cells age- senescent (mesenchyme become senescent much slower; divide longer than the more differentiated cell)

Answer 251

There are a huge number of potential 'biomaterials', both synthetic and naturally occuring multiple challenges to overcome in oral tissue regeneration: microbial infection, inflammation, regeneration Through tissue engineering, it may be possible to manipulate the innate capacity of oral tissue to encourage repair or perhaps regeneration new bioactive materials= more options for practitioners= improved outcomes for patients

Answer 252

biomimetric= mimicry of tissues/processes/structures that are 'biological'

Exam2 Flashcards

(276 cards)