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Bio Materials > Chapter 6,7,8 > Flashcards

Chapter 6,7,8 Flashcards

1
Q

____ are the most frequently placed direct restorations

A

Composites

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2
Q

First tooth color restorative material

A

Silicate cement

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3
Q

Bis-GMA

A

resin monomer developed in 1962. Added silica particles to reinforce it and make it more resistant

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4
Q

Choosing a material depends on

A
  • extent of damage
  • Stress places on the tooth
  • Esthetic requirements of the patient
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5
Q

composite

A

a mixture of 2 or more materials with properties superior to any single component

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6
Q

Composite resins

A

tooth-colored restorative materials, that can be placed anywhere in the mouth

  • composed of mainly organic resin matrix and inorganic filler particles joined together by a silane coupling agent.
  • initiators and accelerated are added to set the material as well as pigment to give color
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7
Q

Most commonly used resin for the organic matrix of composites

A

bis-GMA

  • urethane dimethcrylate is another used resin
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8
Q

Adding filler particles to the organic resin make the composite

A

stronger and more wear-resistant

-also by reducing the amount of resins filler help reduce the amount of shrinkage that occurs when the resin sets
- also reducing the amount of resins reduces thermal expansion and contraction and decreases water sorption (sorption causes resins to soften and more likely to wear)

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9
Q

Composites on radiographs

A

Heavy metal ions are added to composites, to make them wooer radiopaque

-barium, lithium, or strontium

-older composites show radiolucent

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10
Q

Important factors for durability of composites

A
  • size of filler particles
  • ratio or weight of the filler matrix
  • (higher resin= low filler)
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11
Q

Wear of the composite is related to

A
  • filler particle size
    -the amount of filler
    -amount of resin between filler particles
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12
Q

Larger filler particles

A

Tend to get pulled from resin matrix at the surface (plucking) when the restoration is under function or abraded by food and tooth brushing, resulting in wear and a rough surface

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13
Q

coupling agent

A

Is used to provide a stronger bond between inorganic fillers and the resin matrix

-Silane is the agent
- good adhesion is necessary to minimize the loss of filler particles and reduce wear

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14
Q

pigmented resins can be used to

A

-cover discolorations or dark dentin
- Hide graying effect of a metal post in a RCT tooth

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15
Q

Polymerization

A

A chemical reaction the occurs when resin molecules join together end-to-end to form a long chain-molecules to polymers

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16
Q

Chemical/ self cure

A

two paste system
1. base, contains composite and benzoyl peroxide as an initiator
2. Catalyst, contains composite and tertiary amine as an activator

  • equal parts
    -inhibitors are added to each paste to slow down the reaction
  • carriages with mixing tips mix pastes as they are distributed
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17
Q

Light cure

A

most common type
preferred because it requires no mixing and the operator can control working time

The depth of cure in 2mm

contain inhibitor to prevent premature setting due to oratory light

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18
Q

Dual cure

A

area not able to be reached by the blue continues to set
-endodonically treated teeth and placing composite core material in a canal space

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19
Q

Filler sizes

A
  • Macrofilled
    -Microfiller
    -Hybrid
    • Microhybrids
    • Nanohybrids
    • Universal composites
      -Nanocomposites
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20
Q

Composites over time

A
  • Filler size has become smaller
    -number of particles has increased
  • polymerization shrinkage has decreased
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21
Q

Microfilled

A

first generation
Large particles 10-100 microns
roughness and rapid wear, not widely used

22
Q

Microfilled

A
  • Much smaller filler than macro.
    -Lower filler and more resin
    -volume of filler is 35-50% compared to 70-85 with other fillers
  • Lower filler volume =poorer physical properties
  • very shiny when polished
  • Not good for stress-bearing
    -I, II, IV
23
Q

Hybrid

A

Contain both large filler (2-4 microns) and 5-15% microfine filler (.004 to .2)

-combo creates a strong composite that polishes well
-Universal application
-Reduced demand sue to better products

24
Q

Microhybrids

A

-Even smaller particles
- high filler content 70%

25
Nanohybrids
Micro hybrids with nano sized particles added. - increased filler = decreased resin= less shrinkage ( reduces from 3% to less than 1%) -are called universal composites because they are esthetic, wear resistant, and strong therefore can be used in both the anterior and posterior parts of the mouth.
26
Nonocomposites
- 1000 times smaller than conventional fillers - high filler content 78% - Reduces shrinkage and provides strength - anterior and posterior - excellent polish ability and improved wear resistance will remain luster- long term - Very esthetic and more translucent
27
Flowable Composites
-low viscosity, can be lower filled about 40% or more heavily filled 70% - flow and be delivered directly into cavity prep - adapt well to cavity wells - used in place of pits and fissures -Used for class 3 non-carious
28
Pits and fissure sealants
Low viscosity vary in filler content from no to heavy filled prevent dental caries
29
Bulk fill
-speed up placement process - one large increment instead of multiple - a lot of cons Inorder to achieve a greater depth of cure manufactory have increased translucency and reduced mouth of filler
30
Packable
highly viscous material that contains a volume of filler particles - stiff constancy less likely to stick - used posterior class I and III because they are slightly stronger and more wear-resistant - no longer popular but still available
31
Core buildup
Heavy-filled composites used in badly broken-down teeth needing crowns - replace missing tooth structure so there is adequate structure to retain a crown
32
Provisional composites
hold prepared teeth in position so they don't lift and change positions or occlusal relation
33
Biocompatibility
newly placed composites can release chemicals, that could pass tp dental tubules is they aren't sealed with a bonding agent or protected with a base or liner -polished composites are well tolerated by surrounding tissues
34
Composites strength
- most used are similar in compressive strength - not as strong as amalgam but stronger than glass ionomers
35
composite wear
- after than amalgams - lower filler wear faster (microfilled and flowables) - recommend posterior composites are not used for large restoration
36
composite thermal conductivity
transmit hot and cols like a natural tooth structure - greater the filler the lower the CTE, the great resin the Greater CTE
37
Water sorption of composite
The resin matrix absorb water of the oral cavity over time - the more resin the more water is absorbed
38
Incremental placing
-used in modernly or large sized cavity prep - placed in small increments, about 2mm thick -minimizes polymerization shrinkage - light curing accurately penetrates
39
Eugenol
inhibits set of resin
40
Layering (stratification) of composite
apply layers of composite if different shades or degrees of opacity or translucency to obtain a good match for natural teeth
41
Teeth are generally not one color 3 areas:
Cervical part is closest to the dentin color; enamel is thinnest in the cervical part of the tooth Middle of the tooth is called the body area; enamel is thicker in this area than in the cervical area Incisal part is mostly enamel & will be more translucent
42
Finishing
the process used to correct irregularities in contour, remove excess material, and smooth margins and external surfaces
43
Polishing
removes scratches to produce a glossy, very smooth surface
44
Glass ionomers
self-cured and fluoride releasing bond to tooth structure without a bonding agent weaker than composites, shouldn't be used in stress bearing areas used for restoration of root carries
45
Glass ionomers properties
Biocompatibility- tolerated well, kind to pulp and soft tissue Bond: bonds to enamel and dentin, maintain their seal to tooth better Releases high levels of fluoride initially, absorbs fluoride from in-office applications CTE; similar to normal tooth structure good insulator again temp extremes
46
Luting cements
popular, are pulp ally kind, bond to tooth structure and release fluoride. Low film thickness to seat crowns easily
47
Glass ionomer cement as fissure sealant
- used because fluoride release - not retained as well as resin Thick and dosent penetrate pits and fissures as well
48
Atraumatic restorative treatment
allows non dental trained personnel to help stop or slow down the progression of open carious lesions with a drill -gig out as much decay - High viscosity glass ionomer composite is used
49
Compomers
Composite resin that have modified with polyacid idea was to marry good qualities of composites with fluoride reading abilities of glass ionomer - fluoride release is delayed for months low stress class III and V
50
Giomers
new hybrid materials Properties of glade ionomer and composite Fluoride release, slower and less. Can be recharged with fluoride TP and rinse - single paste syringes our flowables

Bio Materials (5 decks)

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