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Tooth colored restorative materials
Dr. Emad Farhan Alkhalidi PhD conservative dentistry
2019
* Tooth colored restoration
Tooth-colored restorative materials have been used to replace missing tooth structure and to modify tooth color and thus enhancing facial esthetic.Dr. Emad Farhan Alkhalidi PhD conservative dentistry
* During the last 20 years, the increasing demands and continuous search for esthetics restorative material which have tooth like appearance, have led to the development and improvement not only in the material itself (physical and mechanical properties ). but also the technique of the replacement.
Dr. Emad Farhan Alkhalidi PhD conservative dentistry
* A composite as the name implies consists of two or more materials each of these materials contributes to the overall properties of the composite. Resin based composite are possibly the most ubiquitous materials available in dentistry as they are used in a huge variety of clinical applications ranging from filling materials, luting agents indirect restorations.
Dr. Emad Farhan Alkhalidi PhD conservative dentistry
* Historical development
Silicate cement : The first tooth colored restorative material was used is silicate cement , was introduced in 1878 by Fletcher in England. it was supplied as a powder and liquid system. the powder is composed of acid soluble glasses and the liquid contains phosphoric acid , water and buffering agent.Dr. Emad Farhan Alkhalidi PhD conservative dentistry
* It was used extensively to replace carious teeth for the anterior area for over 60 years because of its advantage of releasing fluoride (anti cariogenic effect). It is disadvantages include solubility, marginal discoloration, loss of contour and rough texture. It is no longer be used now.
Dr. Emad Farhan Alkhalidi PhD conservative dentistry
* Self cure acrylic :
The self cure acrylic resin (chemical activated) for anterior restoration was developed in 1940 to over come the problem associated with silicate cement.Dr. Emad Farhan Alkhalidi PhD conservative dentistry
* several unfavorable physical properties prevented acrylic resin from being an ideal restorative material which include poor wear resistance ,low strength, its high polymerization shrinkage and higher coefficient of thermal expansion which cause micro leakage and eventual discoloration at the margins.
Dr. Emad Farhan Alkhalidi PhD conservative dentistry
* Composite
In an effort to improve the physical properties of unfilled acrylic resin, apolymeric restorative material reinforced with silica particles was introduced in 1962.Dr. Emad Farhan Alkhalidi PhD conservative dentistry
* Composites are presently the most popular tooth colored restorative material having largely replaced silicate and acrylic resin.
Dr. Emad Farhan Alkhalidi PhD conservative dentistry
* Composition :
Resin composite generally consist of three primary ingredients: an organic matrix , inorganic filler particles and a coupling agent . other ingredients include color stabilizer, inhibitors, pigments and activation system.Dr. Emad Farhan Alkhalidi PhD conservative dentistry
* A:-Matrix phase
Most dental composite contain matrix phase which is BisGMA (Bis-Glycidylate Methacrylate) or urethane Dimethacrylate (UEDMA).OCH2CHCH2O-C-C=CH2
CH2=C-C-O-CH2CH-CH2O
-C-
CH3
CH3
CH3
CH3
OH
OH
O
O
Bis-GMA
Dr. Emad Farhan Alkhalidi PhD conservative dentistry
* The function of matrix phase is to make the initial mixture fluid and moldable for placement into a cavity preparation and penetrate the micro mechanical spaces on etched enamel and dentin.
Dr. Emad Farhan Alkhalidi PhD conservative dentistry
* B:- Dispersed phase (filler)
This inorganic filler phase consists of ceramic like material that disperse through out the resin matrix (e.g. silica, quartz, silicate , or barium glasses or strontium glasses).Dr. Emad Farhan Alkhalidi PhD conservative dentistry
* The inorganic filler significantly enhance the physical properties of the composite by :- 1-increasing the strength of the material . 2-reducing the coefficient of thermal expansion. 3-reducing polymerization shrinkage. 4-Low water absorption. 5-Easy of manipulation and finishing. 6-increase viscosity. 7-Increase wear resistance. 8-Good color matching. 9-Color stability.
Dr. Emad Farhan Alkhalidi PhD conservative dentistry
* At most all important properties of composite are improved by using higher filler content . the only practical problem is that as filler levels increase , the fluidity is decreased (become highly viscous.)
Dr. Emad Farhan Alkhalidi PhD conservative dentistry
* C:- Interfacial coupling agent
For a composite to have good mechanical properties a strong bond must exist between the organic resin matrix and the inorganic filler .this bond is achieved by coating the filler particles with a silane coupling agent which not only increase the strength of the composite but also reduce its solubility and water absorption.Dr. Emad Farhan Alkhalidi PhD conservative dentistry
Coupling Agent
Chemical bond filler particle - resin matrix transfers stresses Organosilane (bifunctional molecule) siloxane end bonds to hydroxyl groups on filler methacrylate end polymerizes with resinCH3-C-C-O-CH2-CH2-CH2-Si-OH
CH2
O
OH
OH
Bonds with filler
Silane
Bis-GMA
Bonds with resin
Phillip’s Science of Dental Materials 2003
* Polymerization of the composite :-
The matrix monomer can be polymerized or cured in a Varity of ways.Dr. Emad Farhan Alkhalidi PhD conservative dentistry
* A) chemical cured system
Also called self cured or two component system. These resins are supplied as two paste systems with one paste containing tertiary amine as activator and other containing benzyl peroxide as initiator. When the two systems are mixed together the polymerization is initiated . it is used widely in orthodontic treatment .Dr. Emad Farhan Alkhalidi PhD conservative dentistry
* Disadvantages
the operator has no control of the working time after the material has been mixed , thus both insertion and contouring must be finished soon after the initiating of mixing. Possible incorporation of air bubbles during mixing of the two pastes , resulting in porous mix with a reduced wear resistance and high tendency to staining and color changes.* B) Light cured system.
Include 1- ultra violet light cure 2- visible light cure. 3- high intensity light cure.(argon laser, plasma arc curing system) 4- light emitting diodes (LED)Dr. Emad Farhan Alkhalidi PhD conservative dentistry
* Ultra violet light cure system
An alternative way to chemical cured was introduced that use ultraviolet light to initiate polymerization.Dr. Emad Farhan Alkhalidi PhD conservative dentistry
* Disadvantages
1-possibility of retina and soft tissue damage. 2- it requires approximately 60 sec. to cure adepth of 1.5 mm. 3- density of light source reduced with the time.Dr. Emad Farhan Alkhalidi PhD conservative dentistry
* Visible light cure system
Which is the most popular method for curing system used now days . they are integral part of modern adhesive dentistry.Dr. Emad Farhan Alkhalidi PhD conservative dentistry
* The composite material used in case of light cured system are supplied as single paste contained in a syringe or capsule, the initiating system consist of photoinitiater and amin activator both are contained in the same syringe and when the paste is exposed to light it start to polymerize.
* Advantage of visible light cure system and material.
1-longer working time. 2- reduced porosity. 3- it takes a20-40 sec .to cure in a depth of 1.5-2mm 4- reduced waste of material. 5- better resistance to wear and abrasion* High intensity light units
They have recently been marked that are capable of curing resin composite more quickly than visible light. they increases the polymerization rate, very short exposure time and ensure deep curing .* Light emitting diodes
Advantages :- 1-it can run or rechargeable battery power 2-bulb life of the light is at least 10 times longer than that of visible light 3-produce less heat as compared to that of visible light cure system* C :- dual cured system
It combines self curing and light curing system. The self curing rate is slow and is designed to cure only those portions that are not adequately light cured , such as cementation of ceramic inlays that may be too thick to allow a sufficient amount of light to radiate through to produce adequate conversion of monomer.* Classification of the composite A :-classification based on the method of activation. B :-classification based (according )to the mean particle size of the major filler . Composites are usually divided into three types based primarily on size , amount and composition of the inorganic filler.
* 1-conventional (traditional) composite:- - it contains 75- 80 % inorganic filler lay weight - particle size is 5-25 Mm with average particle size is 8 Mm. - because of the large size of filler particles. Conventional composite exhibits a rough surface texture.
* the resin matrix wears at a faster rate than filler particles resulting in a rough surface and susceptibility for discoloration . polishing ability is lower and the staining is more than other types.
* 2-microfilled composite :- contains colloidal silica particle with average diameter ranges from 0.01 to 0.04 Mm typically micro filled have an inorganic filler content of approximately 35% to 60% by weight. Because of small particle size the restoration exhibit a smooth luster surface similar to that of tooth structure.
* Micro filled composite are clinically very wear resistant ,also their low modulus of elasticity may allow micro filled composite restoration to flex during tooth flexure,thus better protecting the bonding interface , this make the micro filled an appropriate choice for restoring cl V cervical lesion when cervical flexure can be significant “ bruxism , clenchers and stressful occlusion
* Hybrid composite combines the physical and mechanical properties of conventional composite with smooth surface typical of micro filled composite. It has an organic filler content for approximately 75-85% by weight. The average particle size (0.4 to 1Mm). hybrid composite currently are the predominant direct esthetic restoratives material of choice.
* Flowable composite: Have lower filler content and sequent inferior physical properties such as lower wear resistance and strength. may be used in small cI restoration, pit and fissure sealant , marginal repair. Used as a first increment placed as liner under hypride prepackable composite .
* Packable composite: these types of restoration were introduced to be used in the posterior area (stress bearing area) instead of amalgam restoration. More viscous than other types of the composite giving the similarity of the handling of the amalgam restoration. Other material which have tooth like appearance include.
Willems ClassificationThis classification is far more complex, but provides more informations about the mean particle size, filler distribution, filler contents, Young’s modulus, hardness, and filler morphology. Thus, it links the composition with a number of important clinical characteristics and physical properties (Willems et al., 1991). This classification includes the following categories
Densified composite, Microfine composite, Miscellaneous composite, Traditional composite , and Fiber-reinforced composite
Newer Classification System
Based on particle size megafill 0.5 - 2 millimeters macrofill 10 - 100 microns midifill 1 - 10 microns minifill 0.1 - 1 microns microfill 0.01 - 0.1 microns nanofill 0.005-0.01 micronsMost new systems minifillers Newest trend nanofillers trimodal loading prepolymerized
* Bayne JADA 1994
I MPORTANT PROPERTIES There are considerations regarding various properties of composites that must be understood if a successful composite restoration is to be done.
Linear Coefficient of Thermal Expansion. The linear coefficient of thermal expansion (LCTE) is the rate of dimensional change of a material per unit change in temperature.
The closer the LCTE of the material is to the LCTE of enamel, the less chance there is for creating voids or openings at the junction of the material and the tooth when temperature changes occur.
The LCTE of improved composites is approximately three times that of tooth structure; that for hybrid glass ionomer is 1.5 to 2 times that of tooth structure. Bonding a composite to etched tooth structure reduces the potential negative effects due to the difference between the LCTE of tooth structure and that of the material.
Water Absorption: Water absorption is the amount of water that a material absorbs over time per unit of surface area or volume. When a restorative material absorbs water, its properties change, and therefore its effectiveness as a restorative material is usually diminished.
Wear Resistance. Wear resistance refers to a material's ability to resist surface loss as a result of abrasive contact with opposing tooth structure, restorative material, food boli, and such items as toothbrush bristles and toothpicks. The filler particle size, shape, and content affect the potential wear of composites and other tooth-colored restorative materials
The location of the restoration in the dental arch and occlusal contact relationships also affect the potential wear of these materials. Wear resistance of composite materials is generally good.
While not yet as resistant as amalgam, the difference is becoming smaller. A composite restoration offers stable occlusal relationship potential in most clinical conditions, particularly if the occlusal contacts are shared with those on natural tooth structure.
SurfaceTexture. Surface texture is the smoothness of the surface of the restorative material. Restorations in close approximation to gingival tissues require surface smoothness for optimal gingival health.
Radiopacity. Esthetic restorative materials must be sufficiently radiopaque, so that the radiolucent image of recurrent caries around or under a restoration can be more easily seen in a radiograph. Most composites contain radiopaque fillers, such as barium glass, to make the material radiopaque.
Modulus of Elasticity. Modulus of elasticity is the stiffness of a material. A material having a higher modulus is more rigid; conversely, a material with a lower modulus is more flexible. A microfill composite material with greater flexibility may perform better in certain Class V restorations than a more rigid hybrid composite.
Solubility. Solubility is the loss in weight per unit surface area or volume due to dissolution or disintegration of a material in oral fluids, over time, at a given temperature. Composite materials do not demonstrate any clinically relevant solubility.
POLYMERIZATION OF COMPOSITE Polymerization Shrinkage. Composite materials shrink while hardening. This is referred to as polymerization shrinkage. This phenomenon cannot be avoided, and there are important clinical procedural techniques that must be incorporated to help offset the potential problems associated with a material pulling away from the preparation walls as it hardens.
Careful control of the amount and insertion point of the material and appropriate placement of etchant, primer, and adhesive on the prepared tooth structure to improve bonding reduces these problems. Polymerization shrinkage usually does not cause significant problems with restorations cured in preparations having all-enamel margins.
An important clinical consideration regarding the effects of polymerization shrinkage is the configuration factor (C-factor). The C-factor is the ratio of bonded surfaces to the unbonded, or free, surfaces in a tooth preparation. The higher the C-factor, the greater is the potential for bond disruption from polymerization effects.
Dr. Emad Farhan Alkhalidi PhD conservative dentistry
Dr. Emad Farhan Alkhalidi PhD conservative dentistry
Dr. Emad Farhan Alkhalidi PhD conservative dentistryDr. Emad Farhan Alkhalidi PhD conservative dentistry
Dr. Emad Farhan Alkhalidi PhD conservative dentistryFor example, a Class IV restoration (one bonded surface and four unbonded surfaces) with a C-factor of 0.25 is at low risk for adverse polymerization shrinkage effects. However, a Class I restoration with a C-factor of five (five bonded surfaces, one unbonded surface) is at much higher risk of bond disruption associated with polymerization shrinkage, (e.g., Class I preparations with a high C-factor) by using: (1) "soft-start" polymerization instead of high-intensity light-curing, (2) incremental additions to reduce the effects of polymerization shrinkage, and (3) a stress-breaking liner, such as a filled dentinal adhesive.
C- factor (INTERNAL STRESSES)
can be reduced by:1) ‘Soft start’ Polymerization2) Incremental placement3) Use of stress breaking liners such as:-a)Filled Dentinal Adhesivesb)RMGI. Dr. Emad Farhan Alkhalidi PhD conservative dentistryI NDICATIONS Composite can be used for most clinical applications. Generally, the indications for use are: 1. Classes I, II, III, IV, V and VI restorations 2. Foundations or core buildups 3. Sealants and conservative composite restorations(preventive resin restorations)
4. Esthetic enhancement procedures Partial veneers ,Full veneers ,Tooth contour modifications, Diastema closures 5. Cements (for indirect restorations) 6. Temporary restorations 7. Periodontal splinting
CONTRAINDICATIONS If the operating site cannot be isolated from Contamination If all of the occlusion will be on the restorative material, composite may again not be the choice for use.
If composite restoration extensions on the root surface.
ADVANTAGES3. Less complex when preparing the tooth 4. Insulative, having low thermal conductivity 5. Used almost universally 6. Bonded to tooth structure, resulting in good retention,low microleakage, minimal interfacial staining,and increased strength of remaining tooth structure 7. Repairable
2. Are more difficult, time-consuming, and costly (compared to amalgam restorations) because: Tooth treatment usually requires multiple steps. Insertion is more difficult. Establishing proximal contacts, axial contours, embrasures, and occlusal contacts may be more difficult. Finishing and polishing procedures are more difficult.
3. Are more technique sensitive because the operating site must be appropriately isolated and the placement of etchant, primer, and adhesive on the tooth structure (enamel and dentin) is very demanding of proper technique
4. May exhibit greater occlusal wear in areas of high occlusal stress or when all of the tooth's occlusal contacts are on the composite material
5. Have a higher linear coefficient of thermal expansion,resulting in potential marginal percolation if an inadequate bonding technique is utilized.