Resin Composite Restoration PDF

RESIN COMPOSITE RESTORATIONS DR. FATEMA ALDABBAR. MASTER DEGREE OF OPREATIVE DENTISTRY An esthetic restorative material. The term composite refers to a material that is composed of two or more constituents that are insoluble in each other. This combination produces a material with superior or inte...

RESIN COMPOSITE RESTORATIONS DR. FATEMA ALDABBAR. MASTER DEGREE OF OPREATIVE DENTISTRY An esthetic restorative material. The term composite refers to a material that is composed of two or more constituents that are insoluble in each other. This combination produces a material with superior or intermediate. properties ,resin composite restoration has undergone many modifications and is currently being widely used in treatment of anterior as well as posterior teeth. COMPOSITION: Resin composites consist of an organic resin matrix and inorganic filler particles bonded together by an organic coupling agent. A. THE ORGANIC RESIN MATRIX: It is the continuous phase to which other ingredients are added. It comprises: 1. High molecular weight monomers: Most systems are based on Bisphenol glycidyl methacrylate (BisGMA) monomer, some are based on Urethane Dimethacrylate (UDMA) monomer and others incorporate a mixture of both BisGMA and UDMA. Both resins are extremely viscous. This decreases the amount of filler that can be incorporated into the monomer. A. THE ORGANIC RESIN MATRIX: 2. Low molecular weight monomer: A low-viscosity monomer e.g. Triethylene Glycol Dimethacrylate (TEG-DMA) is thus added as a diluent to provide more fluidity for the material. It decreases the viscosity, increases the wettability and results in improved mechanical properties. However, it results in more polymerization shrinkage and increases the affinity to water sorption as it is more hydrophillic. A. THE ORGANIC RESIN MATRIX: 3. Activator/Initiator system: Matrix monomers in direct resin composite systems could be poly merized either through 1-chemical-curing (auto- or self-cure):)Not used today). Chemically- polymerized systems comprises two-paste system. 2-photo-chemical through light activation: comprise one paste only. The paste contains a photo-sensitive chemical e.g. camphorquinone (diketone), which absorbs visible light. A. THE ORGANIC RESIN MATRIX: 3-dual-cured through both mechanisms: polymerized systems combine both versions. They start by photochemical reaction and continue by a chemical process. A. THE ORGANIC RESIN MATRIX: 4. Inhibitors: Prevents spontaneous polymerization. This increases The shelflife and the working time of the material. 5. Pigments: contains metal oxides pigments to provide composite with different shades and opacity to match the color and translucency of the tooth. B. THE INORGANIC FILLERS: The fillers are the dispersed phase which is added to improve the strength, wear resistance and optical characteristics of the material. They decrease the polymerization shrinkage, coefficient of thermal expansion and water sorption. However, they increase the viscosity. B. THE INORGANIC FILLERS: Types of filler: It is formed of inorganic silica either in: #crystalline form such as quartz, stronger and harder but difficult to finish and polish. Therefore, most current composites comprise silicate glass. # non-crystalline form such as glass. B. THE INORGANIC FILLERS: Filler particle size and loading: As the particle size decreases, the polishability and wear resistance of composites increases. While as the filler loading (% of filler content) increases, the mechanical properties of composite is enhanced. Thus, the ideal composite would be highly filled with very small particles. Unfortunately, loading a composite with large amount of small filler is difficult because the large surface area causes a marked increase in viscosity. C. The coupling agent: It is used to bind the filler particles to the organic resin matrix. An organo-silane is used with bifunctional molecule. One end forms siloxane bonds with hydroxyl group of the silica filler while the other end is capable of copolymerizing with the monomers of the matrix. Its function is very critical as it allows proper stress transfer between the resin phase and the filler, thus increasing strength and rigidity as well as the wear resistance of the composite. It also provides hydrolytic stability by preventing water from penetrating along the resin-filler interface. CLASSIFICATION AND TYPES OF RESIN COMPOSITES: A. According to filler size: a)Macrofilled composites. b)Microfilled composites. c)Hybrid composites. d)Nanofilled composites. a)Macrofilled composites:- They were non-polishable, because during polishing, the weaker organic matrix will abrade more, leaving the hard fillers in place and producing a rough surface CLASSIFICATION AND TYPES OF RESIN COMPOSITES: b)Microfilled composites:- They are polishable, have smooth and lustrous surface, with good wear resistance due to small filler size, but with low mechanical properties due to high resin content. Their use is thus restricted to non-stress bearing areas where esthetics and smoothness of restoration is of prime importance and as veneers for other composites. There are two types of microfilled composites; homogenous and heterogeneous. Classification and Types of resin composites: c)Hybrid composites:- have combination of colloidal silica microfillers and glass macrofillers, They combine the advantages of both, where satisfactory mechanical properties are combined with adequate esthetics and good surface characteristics. hybrid type, e.g. minifilled hybrid, microfilled hybrid. d)Nanofilled composites:- The filler size is below the wavelength range of visible light, thus they do not produce scattering nor significant absortion of light. This will lead to thorough polymerization of the resin matrix. Classification and Types of resin composites: B. According to filler loading and consistency; Packable composites:- It is also referred to as high density or condensable composites. They are composites with high filler loading and large particle size. They also have good fracture resistance. However, they have several disadvantages; they have poor adaptation to cavity walls as well as between successive increments and poor wear resistance due to large filler particles. Classification and Types of resin composites: Flowable composites: A flowable composite is a low-filled composite with low viscosity. They have two main advantages; increased adaptability and increased elasticity. They are indicated in cervical lesions, and as a liner/base under composites to provide an elastic layer that can absorb polymerization shrinkage stresses, they have inferior mechanical properties. Classification and Types of resin composites: C. According to type of resin matrix: a) regular methyl methacrylate resins matrix. b) silorane resin matrix:- The recently introduced low-shrinkage composite is based on the silorane resin and does not contain methacrylate resins. The silorane resin is more hydrophobic than conventional methacrylate resin, so this results in; decreases wettability and adaptation. Classification and Types of resin composites: D. According to technique of polymerization: - Chemical cure composite - Light cure composite - Dual cure composite Classification and Types of resin composites: F. According to technique of packing: - Incrementally packed composite. - Bulk-fill composites. - Types of bulk-fill composite: -- #Conventional consistency bulk-fill composites. - #Flowable bulk-fill composites.- ADVANTAGES OF RESIN COMPOSITES: 1. Superior esthetic quality. 2. Satisfactory physical and mechanical properties. 3. Combined with adhesives, the conserve and reinforce tooth structure. 4. Have low thermal conductivity. 5. They are easy to repair. DISADVANTAGES OF RESIN COMPOSITE: 1) Questionable adaptation to tooth structure due to:High polymerization shrinkage, Poor wettability to tooth structure. 2) May exhibit high occlusal wear in areas of high occlusal stress or when all occlusal contacts are on the composite restoration and not shared by tooth structure. 3) Hydrolytic Instability in the oral fluids. 4) High technique sensitivity. 5) Conventional composites lack anticariogenic potential by fluoride release. INDICATIONS OF RESIN COMPOSITE: 1. Can be used in all Classes of cavity preparations whether originating from carious or non carious lesions. (Class I, II, III, IV, V and VI). 2. Used in esthetic enhancement procedures; including correction of tooth form and contour (shape or size) , diastema closure and partial or complete veneer for discolored or defective teeth. INDICATIONS OF RESIN COMPOSITE: 3. Used as core build-up material under crowns and bridges. 4. Used for cementation of indirect esthetic restorations (resin cement). 5. Used in repair of restorations, periodontal splinting and bonding of orthodontic brackets. CONTRAINDICATIONS OF RESIN COMPOSITES: 1. Patients with bad oral hygiene and high caries index. 2. If the operating site cannot be properly isolated from oral fluids. 3. Patients with heavy occlusal stresses due to unfavorable occlusion or bruxism. CAVITY PREPARATION DESIGN FOR RESIN COMPOSITE RESTORATION: bonding to enamel and dentin, has modified the classic cavity preparation into what is known as the “adhesive cavity design”. The adhesive cavity design is characterized by: 1. Preservation of tooth structure: The cavity outline is limited only to defective enamel and dentin, with no extension in depth or width. 2. Beveled cavo-surface angle: The enamel walls forming the boundaries of the cavity are beveled to a 45° short bevel. CAVITY PREPARATION DESIGN FOR RESIN COMPOSITE RESTORATION: Advantage of the bevel:- a) Increases the surface area of enamel available for bonding, with better marginal sealing and stronger micromechanical retention. b) Exposes the ends of enamel rods, rather than the sides which provides for a more retentive etching pattern with micro-pores in enamel prisms and macro-pores in inter-prismatic substance following acid etching. c) Better esthetics because of gradual color degradation between tooth and restoration. CAVITY PREPARATION DESIGN FOR RESIN COMPOSITE RESTORATION: The width of the bevel is usually 0.5-1mm. In addition, smooth rounded indentations could be made inside the bevel (scalloping) to further increase the surface area. However, the bevel is contraindicated in: #Stress bearing areas, e.g. in occlusal surface of posterior teeth. #to avoid chipping of composite in such areas if restoration is finished into thin margins. #In addition enamel in gingival wall is not beveled to avoid chipping of thin enamel at the margin. 3. Rounded line and point angles. CAVITY PREPARATION DESIGN FOR RESIN COMPOSITE RESTORATION: The cavity preparation for resin composite is relatively easy and less complex than that for amalgam. However, manipulation and steps of application of resin composite restoration are more difficult and technique sensitive; it requires a meticulous skillful operator to obtain a durable successful composite restoration. STEPS OF APPLICATION OF RESIN COMPOSITE RESTORATION: 1. Selection of resin composite type. 2. Shade selection. 3. Isolation of the operatory field. 4. Application of liner/base (if needed). 5. Matricing and wedging. 6. Application of adhesive system. 7. Packing and curing of composite. 8. Finishing and polishing.