Chapter 6,7,8 Flashcards
____ are the most frequently placed direct restorations
Composites
First tooth color restorative material
Silicate cement
Bis-GMA
resin monomer developed in 1962. Added silica particles to reinforce it and make it more resistant
Choosing a material depends on
- extent of damage
- Stress places on the tooth
- Esthetic requirements of the patient
composite
a mixture of 2 or more materials with properties superior to any single component
Composite resins
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
Most commonly used resin for the organic matrix of composites
bis-GMA
- urethane dimethcrylate is another used resin
Adding filler particles to the organic resin make the composite
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)
Composites on radiographs
Heavy metal ions are added to composites, to make them wooer radiopaque
-barium, lithium, or strontium
-older composites show radiolucent
Important factors for durability of composites
- size of filler particles
- ratio or weight of the filler matrix
- (higher resin= low filler)
Wear of the composite is related to
- filler particle size
-the amount of filler
-amount of resin between filler particles
Larger filler particles
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
coupling agent
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
pigmented resins can be used to
-cover discolorations or dark dentin
- Hide graying effect of a metal post in a RCT tooth
Polymerization
A chemical reaction the occurs when resin molecules join together end-to-end to form a long chain-molecules to polymers
Chemical/ self cure
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
Light cure
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
Dual cure
area not able to be reached by the blue continues to set
-endodonically treated teeth and placing composite core material in a canal space
Filler sizes
- Macrofilled
-Microfiller
-Hybrid- Microhybrids
- Nanohybrids
- Universal composites
-Nanocomposites
Composites over time
- Filler size has become smaller
-number of particles has increased - polymerization shrinkage has decreased
Microfilled
first generation
Large particles 10-100 microns
roughness and rapid wear, not widely used
Microfilled
- 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
Hybrid
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
Microhybrids
-Even smaller particles
- high filler content 70%
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.
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
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
Pits and fissure sealants
Low viscosity
vary in filler content from no to heavy filled
prevent dental caries
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
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
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
Provisional composites
hold prepared teeth in position so they don’t lift and change positions or occlusal relation
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
Composites strength
- most used are similar in compressive strength
- not as strong as amalgam but stronger than glass ionomers
composite wear
- after than amalgams
- lower filler wear faster (microfilled and flowables)
- recommend posterior composites are not used for large restoration
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
Water sorption of composite
The resin matrix absorb water of the oral cavity over time
- the more resin the more water is absorbed
Incremental placing
-used in modernly or large sized cavity prep
- placed in small increments, about 2mm thick
-minimizes polymerization shrinkage
- light curing accurately penetrates
Eugenol
inhibits set of resin
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
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
Finishing
the process used to correct irregularities in contour, remove excess material, and smooth margins and external surfaces
Polishing
removes scratches to produce a glossy, very smooth surface
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
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
Luting cements
popular, are pulp ally kind, bond to tooth structure and release fluoride.
Low film thickness to seat crowns easily
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
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
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
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
