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- Pages: 33
10/14/08
1
Composite Resin Restoration
10/14/08
Dr. Ahlam A. Imam. Prof.,Dept. Operative Dentistry, Faculty of Oral and Dental Med., Cairo University.
2
Composite Resin Restoration Composite materials generally are formed from two constituents that are insoluble in each others. The combination of materials, composite, provides a material with properties that are superior or intermediate to those of the individual constituents. e.g., The resin matrix is reinforced by glass fibers. The resulting composite is harder and stiffer than the resin matrix, but less brittle than the glass. 10/14/08
3
Composition and Chemistry:
Composite resins consists of three phases: Matrix phase. Dispersed phase. Coupling phase.
10/14/08
4
Matrix phase: (Organic resin matrix phase).
Monomer systems of most present day resin composite are based on Bis-GMA. In the remaining resin composites, urethane dimethacrylate is used as the basis of monomer system. Its low viscosity allows an increase in filler loading without the need of the addition of low-molecular weight monomers to lower viscosity. However, urethane dimethacrylate is more brittle and undergoes more polymerization shrinkage than Bis-GMA.
A diluent: (such as triethylene glycoldimethacrylate “TEGDMA”) is often added to control viscosity and make the resin more flexible and less brittle.
10/14/08
5
Initiators and accelerators are added to produce the free radicals needed for polymerization: A chemically activated system uses benzoyl peroxide (initiator), which reacts with a tertiary aromatic amine (accelerator or activator) to produce free radicals. In the ultraviolet system, a 365 nm light source can split benzoyl methyl ether into free radicals. Most visible light cured systems utilize 468 + 20 nm light source to cause camphoroquinone to react with an aliphatic amine to initiate free radical production. N.B An aliphatic amine is more color stable than the aromatic amine used in chemically cured formulations, hence the improved color stability of light cured resin system.
10/14/08
6
Inhibitors (stabilizers) such as
hydroquinone may be added to prevent premature polymerization and to increase shelf-life of the chemically cured system. They must also contain pigments to color the material so that it matches the tooth structure. Color stabilizer: chemically cured and light cured may contain ultraviolet absorbing compounds, which act as color stabilizer. 10/14/08
7
The Dispersed Phase (filler) Inorganic filler: Common filler particles include quartz, lithium, aluminum silicate, barium and other glasses. Organic filler: These are precured particles that are produced by grinding cured composite to a size ranging from 1-20 um. They could also be produced by sintering small particles into large but porous ones and impregnated them with monomer. 10/14/08
8
Filler particle size
10/14/08
9
Schematic Examples Different Filler Particle Sizes
Mixtures Of Filler Sizes
Mixtures Of PreCured Pieces of Composite 10/14/08
10
Filler Loading
Filler particles constitute about 75-80% of the resin by weight. The volume percent is usually 10-25% less than the weight percent.
10/14/08
11
Filler particles are added to improve physical properties i.e.:
10/14/08
Reduce water sorption. Reduce polymerization shrinkage( since less resin is present) Reduce the coefficient of thermal expansion. Increase the hardness of the resin matrix.
12
Mechanical properties such as compressive strength, tensile strength, modulus of elasticity and abrasion resistance are also improved by adding the fillers.
10/14/08
13
Coupling phase: That results in the adherence of the matrix to the filler particles (e.g. silanes). Coupling agents provide hydrolytic stability by preventing water from penetrating along the filler-resin interface. Be aware: The resin component of a cured dental resin composite is a polymeric matrix (A polymer is a large molecule built up by repetitive bonding together of many smaller units called monomer). The process by which monomers are joined together and converted into polymers is called polymerization the extent to which monomer is changed into polymer is termed the degree of conversion.
10/14/08
14
Types of composites: Composites may be classified according to: A- filler concentration, filler particle size B- Mechanism of polymerization. C- Matrix composition; Bis-GMA-based, UDMA-based, or Mixture of both. A- The most commonly used classification is based on both the filler loading plus the induction system e.g. hybrid VLC, etc. 10/14/08
15
Macrofilled composites:
The most commonly used filler is ground quartz. The average particle size is from 5-30µm, filler loading is 7580% by weight. A major clinical disadvantage is the rough surface texture that develops as a result of abrasive wear of soft resin matrix that leaves the more resistant hard particles elevated. Finishing of the restoration, tooth brushing and masticatory wear with time produce such rough surface. Rough surface texture restoration more susceptible to discoloration from extrinsic staining. Poor resistance to occlusal wear. These composites are described as nonpolishable. Macrofills have little clinical importance at this time except that some orthodontists still use them.
10/14/08
16
Microfilled composite:
These composites were developed in attempts to improve the polishability. Inorganic filler content of approximately 40-50% by weight. Filler are 0.02-0.4µm Microfill composites polish very smooth and lustrous. The problem with microfilled composite is the low percent filler and high resin content. This result in an increased coefficient of thermal expansion and lower strength. Currently, microfilled composites are used when esthetics are the dominant concern. Be aware: Optimal polish is obtained at the expense of physical properties. So it become the resin of choice for esthetic restoration of anterior teeth particularly in non-stress bearing situations.
10/14/08
17
Hybrid composites
As the name indicate, there are two kinds of filler particles in the hybrid composites: Colloidal silica and ground particles of glasses of heavy metals. The total filler content 75-80% by weight, colloidal silica represents 10-20% by weight of the total filler content. Average particle size of filler 0.6-1.0µm. They combine the advantages of both the macrofilled and microfilled types. So these resins can receive a high polish, their strength and abrasion resistance are acceptable for small to medium class 1 and 2 restorations.
10/14/08
18
Flowable composites
light cured, low-viscosity composite. Filler loading 42-50% by volume. Manufacturers have decreased the filler content of the material to reduce the viscosity and increase flow of these materials. A weaker, less abrasion resistant material results. Particle size 0.7-3.0µm Recommended for cervical, pediatric restoration and small, low-stress bearing restorations.
10/14/08
19
Flowable composites
Flowable composites are typically used as the initial increment of composite restoration and then covered with a hybrid material. The two main advantages of these materials are increased elasticity and ready adaptability to the internal cavity surfaces during their application. This prevents trapping of air and the formation of air bubbles common with traditional composite resins.
10/14/08
20
Flowable composites
Their elasticity has a great advantage since having an elastic layer between the dentin and the restorative material, could absorb the polymerization stress, thereby acting as a major safe guard against disruption of the adhesive surface. It is for this reason that these materials are being used more and more as a base or lining for direct, semi-direct and indirect restoration.
10/14/08
21
Flowable composites
10/14/08
That is to say, “Flowable composites” were created to facilitate the adaptation of composite increments to cavity preparation walls. These were fabricated with increased resin (i.e., lower filler content) and therefore lower strengths.
22
Condensable composites, (packable or compactable)
10/14/08
“Packable composites” (or condensable composites) were designed to be stiffer and handle more like dental amalgam, in an effort to make it easier for dental amalgam users to shift over to composite use. Filler loading is 66-70% by volume. The properties of these materials are very similar to standard hybrids.
23
Packable composites
10/14/08
Packable composites are intended to be “non-sticky” versions of hybrids that can be easily packed or condensed into cavity preparations in a manner that simulates the placement of a dental amalgam. Only clinical research will determine if these materials are truly an improvement over the current products.
24
Poly acid- modified resin composite
Resin – modified glass - ionomer set with an acid – base reaction in addition to photo chemical polymerization. Materials that contain glass - ionomer ingredients but do not exhibit an acid-base reaction are called polyacid – modified resin composite, or compomers.
10/14/08
25
Poly acid- modified resin composite
The strength of compomers is lower than composites (but higher than that of resin-modified glass-ionomer). The compomer have a relatively high bond strength and fluoride release. Because their modulus of elasticity is close to that of tooth structure, the strain capacity of the restoration is increased and its deformation under a load is prevented, preserving adhesion at the margins of the restoration.
10/14/08
26
B- Classification of composite according to the mechanism of polymerization: Because composite resins are dimethacrylate monomers, they polymerized by the addition mechanism that is initiated by free radicals. Free radicals can be generated by chemical activation or external energy (heat “with special furnaces” and light).
10/14/08
27
Chemically activated resins:
Are supplied as two pastes, one of which contains the benzoyl peroxide initiator, the other contains the tertiary aromatic amine activator. When the two pastes are spatulated the amine reacts with benzoyl peroxide free radicals polymerization. Induction starts during mixing and is completed shortly after packing. They suffer voids inclusion during mixing. They have limited manufacturer controlled mixing time.
10/14/08
28
Light activated resins: a- ultraviolet light (Their use is discontinued)
10/14/08
Such ultraviolet system had problems: Eye hazards Limited penetration depth into the resin resin not adequately polymerized except in very thin layers directly accessible to the light source. Lack of penetration through tooth structure
29
b- Visible light (white light)
VL systems were developed with improved ability to polymerize thicker increments. The depth of cure is limited. Thus, in deep cavities, the restoration must build up in increments, they have totally displaced the UVL system. Light curable composite resin restorations are supplied as a single paste. The free radical initiating system, consisting of the photoinitiator molecule and an amine activator, is contained in this paste. When these two components are left unexposed to light, they do not interact. Exposure to light of the correct wave length produces an excited state of the photoinitator which interacts with amine to form free radicals.
10/14/08
30
Curing Light Types 1- Quartz-Tungesten-Halogen (QTH ) Lights a- Continuous output – normal intensity b- Continuous output – high intensity c- Staged output ( stepped, ramped, … ) 2- Plasma Arc Curing (PAC ) Lights 3- Argon-Laser Curing ( Laser ) Lights 4- Light-Emitting Diode ( LED ) Lights
10/14/08
31
CURING LIGHT TYPES • Quartz-Tungsten-Halogen (QTH) Lights > Continuous output -- normal intensity > Continuous output -- high intensity > Staged output (stepped, ramped, …)
• Plasma Arc Curing (PAC) Lights • Argon-Laser Curing (Laser) Lights • Light-Emitting Diode (LED) Lights
10/14/08
QTH
PAC
Laser
LED
32
C- Dual-Curable
Involves utilization of both chemical and photochemical induction systems for combined advantages: Photochemical polymerization ensures quick and undisturbed polymerization. Chemical polymerization ensures greater degree of conversion throughout the whole restoration regardless of attenuation by thickness, shielding from light or material shade (dark shades require longer exposure times darker colorant tend to absorb light).
10/14/08
33
1
Composite Resin Restoration
10/14/08
Dr. Ahlam A. Imam. Prof.,Dept. Operative Dentistry, Faculty of Oral and Dental Med., Cairo University.
2
Composite Resin Restoration Composite materials generally are formed from two constituents that are insoluble in each others. The combination of materials, composite, provides a material with properties that are superior or intermediate to those of the individual constituents. e.g., The resin matrix is reinforced by glass fibers. The resulting composite is harder and stiffer than the resin matrix, but less brittle than the glass. 10/14/08
3
Composition and Chemistry:
Composite resins consists of three phases: Matrix phase. Dispersed phase. Coupling phase.
10/14/08
4
Matrix phase: (Organic resin matrix phase).
Monomer systems of most present day resin composite are based on Bis-GMA. In the remaining resin composites, urethane dimethacrylate is used as the basis of monomer system. Its low viscosity allows an increase in filler loading without the need of the addition of low-molecular weight monomers to lower viscosity. However, urethane dimethacrylate is more brittle and undergoes more polymerization shrinkage than Bis-GMA.
A diluent: (such as triethylene glycoldimethacrylate “TEGDMA”) is often added to control viscosity and make the resin more flexible and less brittle.
10/14/08
5
Initiators and accelerators are added to produce the free radicals needed for polymerization: A chemically activated system uses benzoyl peroxide (initiator), which reacts with a tertiary aromatic amine (accelerator or activator) to produce free radicals. In the ultraviolet system, a 365 nm light source can split benzoyl methyl ether into free radicals. Most visible light cured systems utilize 468 + 20 nm light source to cause camphoroquinone to react with an aliphatic amine to initiate free radical production. N.B An aliphatic amine is more color stable than the aromatic amine used in chemically cured formulations, hence the improved color stability of light cured resin system.
10/14/08
6
Inhibitors (stabilizers) such as
hydroquinone may be added to prevent premature polymerization and to increase shelf-life of the chemically cured system. They must also contain pigments to color the material so that it matches the tooth structure. Color stabilizer: chemically cured and light cured may contain ultraviolet absorbing compounds, which act as color stabilizer. 10/14/08
7
The Dispersed Phase (filler) Inorganic filler: Common filler particles include quartz, lithium, aluminum silicate, barium and other glasses. Organic filler: These are precured particles that are produced by grinding cured composite to a size ranging from 1-20 um. They could also be produced by sintering small particles into large but porous ones and impregnated them with monomer. 10/14/08
8
Filler particle size
10/14/08
9
Schematic Examples Different Filler Particle Sizes
Mixtures Of Filler Sizes
Mixtures Of PreCured Pieces of Composite 10/14/08
10
Filler Loading
Filler particles constitute about 75-80% of the resin by weight. The volume percent is usually 10-25% less than the weight percent.
10/14/08
11
Filler particles are added to improve physical properties i.e.:
10/14/08
Reduce water sorption. Reduce polymerization shrinkage( since less resin is present) Reduce the coefficient of thermal expansion. Increase the hardness of the resin matrix.
12
Mechanical properties such as compressive strength, tensile strength, modulus of elasticity and abrasion resistance are also improved by adding the fillers.
10/14/08
13
Coupling phase: That results in the adherence of the matrix to the filler particles (e.g. silanes). Coupling agents provide hydrolytic stability by preventing water from penetrating along the filler-resin interface. Be aware: The resin component of a cured dental resin composite is a polymeric matrix (A polymer is a large molecule built up by repetitive bonding together of many smaller units called monomer). The process by which monomers are joined together and converted into polymers is called polymerization the extent to which monomer is changed into polymer is termed the degree of conversion.
10/14/08
14
Types of composites: Composites may be classified according to: A- filler concentration, filler particle size B- Mechanism of polymerization. C- Matrix composition; Bis-GMA-based, UDMA-based, or Mixture of both. A- The most commonly used classification is based on both the filler loading plus the induction system e.g. hybrid VLC, etc. 10/14/08
15
Macrofilled composites:
The most commonly used filler is ground quartz. The average particle size is from 5-30µm, filler loading is 7580% by weight. A major clinical disadvantage is the rough surface texture that develops as a result of abrasive wear of soft resin matrix that leaves the more resistant hard particles elevated. Finishing of the restoration, tooth brushing and masticatory wear with time produce such rough surface. Rough surface texture restoration more susceptible to discoloration from extrinsic staining. Poor resistance to occlusal wear. These composites are described as nonpolishable. Macrofills have little clinical importance at this time except that some orthodontists still use them.
10/14/08
16
Microfilled composite:
These composites were developed in attempts to improve the polishability. Inorganic filler content of approximately 40-50% by weight. Filler are 0.02-0.4µm Microfill composites polish very smooth and lustrous. The problem with microfilled composite is the low percent filler and high resin content. This result in an increased coefficient of thermal expansion and lower strength. Currently, microfilled composites are used when esthetics are the dominant concern. Be aware: Optimal polish is obtained at the expense of physical properties. So it become the resin of choice for esthetic restoration of anterior teeth particularly in non-stress bearing situations.
10/14/08
17
Hybrid composites
As the name indicate, there are two kinds of filler particles in the hybrid composites: Colloidal silica and ground particles of glasses of heavy metals. The total filler content 75-80% by weight, colloidal silica represents 10-20% by weight of the total filler content. Average particle size of filler 0.6-1.0µm. They combine the advantages of both the macrofilled and microfilled types. So these resins can receive a high polish, their strength and abrasion resistance are acceptable for small to medium class 1 and 2 restorations.
10/14/08
18
Flowable composites
light cured, low-viscosity composite. Filler loading 42-50% by volume. Manufacturers have decreased the filler content of the material to reduce the viscosity and increase flow of these materials. A weaker, less abrasion resistant material results. Particle size 0.7-3.0µm Recommended for cervical, pediatric restoration and small, low-stress bearing restorations.
10/14/08
19
Flowable composites
Flowable composites are typically used as the initial increment of composite restoration and then covered with a hybrid material. The two main advantages of these materials are increased elasticity and ready adaptability to the internal cavity surfaces during their application. This prevents trapping of air and the formation of air bubbles common with traditional composite resins.
10/14/08
20
Flowable composites
Their elasticity has a great advantage since having an elastic layer between the dentin and the restorative material, could absorb the polymerization stress, thereby acting as a major safe guard against disruption of the adhesive surface. It is for this reason that these materials are being used more and more as a base or lining for direct, semi-direct and indirect restoration.
10/14/08
21
Flowable composites
10/14/08
That is to say, “Flowable composites” were created to facilitate the adaptation of composite increments to cavity preparation walls. These were fabricated with increased resin (i.e., lower filler content) and therefore lower strengths.
22
Condensable composites, (packable or compactable)
10/14/08
“Packable composites” (or condensable composites) were designed to be stiffer and handle more like dental amalgam, in an effort to make it easier for dental amalgam users to shift over to composite use. Filler loading is 66-70% by volume. The properties of these materials are very similar to standard hybrids.
23
Packable composites
10/14/08
Packable composites are intended to be “non-sticky” versions of hybrids that can be easily packed or condensed into cavity preparations in a manner that simulates the placement of a dental amalgam. Only clinical research will determine if these materials are truly an improvement over the current products.
24
Poly acid- modified resin composite
Resin – modified glass - ionomer set with an acid – base reaction in addition to photo chemical polymerization. Materials that contain glass - ionomer ingredients but do not exhibit an acid-base reaction are called polyacid – modified resin composite, or compomers.
10/14/08
25
Poly acid- modified resin composite
The strength of compomers is lower than composites (but higher than that of resin-modified glass-ionomer). The compomer have a relatively high bond strength and fluoride release. Because their modulus of elasticity is close to that of tooth structure, the strain capacity of the restoration is increased and its deformation under a load is prevented, preserving adhesion at the margins of the restoration.
10/14/08
26
B- Classification of composite according to the mechanism of polymerization: Because composite resins are dimethacrylate monomers, they polymerized by the addition mechanism that is initiated by free radicals. Free radicals can be generated by chemical activation or external energy (heat “with special furnaces” and light).
10/14/08
27
Chemically activated resins:
Are supplied as two pastes, one of which contains the benzoyl peroxide initiator, the other contains the tertiary aromatic amine activator. When the two pastes are spatulated the amine reacts with benzoyl peroxide free radicals polymerization. Induction starts during mixing and is completed shortly after packing. They suffer voids inclusion during mixing. They have limited manufacturer controlled mixing time.
10/14/08
28
Light activated resins: a- ultraviolet light (Their use is discontinued)
10/14/08
Such ultraviolet system had problems: Eye hazards Limited penetration depth into the resin resin not adequately polymerized except in very thin layers directly accessible to the light source. Lack of penetration through tooth structure
29
b- Visible light (white light)
VL systems were developed with improved ability to polymerize thicker increments. The depth of cure is limited. Thus, in deep cavities, the restoration must build up in increments, they have totally displaced the UVL system. Light curable composite resin restorations are supplied as a single paste. The free radical initiating system, consisting of the photoinitiator molecule and an amine activator, is contained in this paste. When these two components are left unexposed to light, they do not interact. Exposure to light of the correct wave length produces an excited state of the photoinitator which interacts with amine to form free radicals.
10/14/08
30
Curing Light Types 1- Quartz-Tungesten-Halogen (QTH ) Lights a- Continuous output – normal intensity b- Continuous output – high intensity c- Staged output ( stepped, ramped, … ) 2- Plasma Arc Curing (PAC ) Lights 3- Argon-Laser Curing ( Laser ) Lights 4- Light-Emitting Diode ( LED ) Lights
10/14/08
31
CURING LIGHT TYPES • Quartz-Tungsten-Halogen (QTH) Lights > Continuous output -- normal intensity > Continuous output -- high intensity > Staged output (stepped, ramped, …)
• Plasma Arc Curing (PAC) Lights • Argon-Laser Curing (Laser) Lights • Light-Emitting Diode (LED) Lights
10/14/08
QTH
PAC
Laser
LED
32
C- Dual-Curable
Involves utilization of both chemical and photochemical induction systems for combined advantages: Photochemical polymerization ensures quick and undisturbed polymerization. Chemical polymerization ensures greater degree of conversion throughout the whole restoration regardless of attenuation by thickness, shielding from light or material shade (dark shades require longer exposure times darker colorant tend to absorb light).
10/14/08
33
