Lecture 4 Composite Restoration Part 1 PDF

Composite Restoration(1) By: Dr. Rehab Alwakeb Operative Dentistry Division Reference: Art and science of operative dentistry 6th edition. “Introduction to Composite Restorations , chapter 8, p:216.” ILOs: I. Define composite material. II. Classify composite resin according to fil...

Composite Restoration(1) By: Dr. Rehab Alwakeb Operative Dentistry Division Reference: Art and science of operative dentistry 6th edition. “Introduction to Composite Restorations , chapter 8, p:216.” ILOs: I. Define composite material. II. Classify composite resin according to filler content and handling characteristics. III. Determine different properties of resin composite restoration. History of resinous material (Unfilled Acrylic Resin) Self-curing (chemically activated) acrylic resin for anterior restorations was developed in Germany in the 1930s. Early acrylic materials were disappointing due to: 1. Poor activator systems. 2. High Polymerization shrinkage. 3. High coefficient of thermal expansion. 4. High wear. Introduction (Acrylic resin) which resulted in: 1. Marginal leakage. 2. Pulp injury. 3. Recurrent caries. 4. Color changes. 5. Loss of contour and contacts. So, are they still being used??  A current, although limited, use of acrylic resin is: for making temporary restorations in operative and fixed prosthodontic “indirect restoration procedures fabrication” requiring two or more appointments. In an effort to improve the physical characteristics of unfilled acrylic resins, a polymeric dental restorative material reinforced with inorganic particles was introduced in 1962 (by Bowen). This filled resin material became the basis for the restorations that are termed composites. Dental Composite material 1. Definition. 2. Components. 3. Classification: a. According to filler (size, amount and composition). b. According to Handling characteristics  I. definition: Composite is a material made from two or more constituents with significantly different physical or chemical properties that, when combined, produce a material with characteristics different from the individual components. II. Components: Matrix Initiators and Filler Accelerators Coupling Agent Pigments  III. classification: a. According to filler size Macrofil Microfil Hybrid Nanofilled 1. Macrofilled or Conventional Composites They are no longer used in clinical practice Contains approximately 75-80% inorganic filler by weight. The average particle size of this composites was approximately 8 μm. as it suffers of rough surface texture. causes the restoration to be more susceptible to discoloration from extrinsic staining  2. Microfilled composite: Microfill composites were introduced in the late 1970s. These materials were designed to replace the rough surface characteristic of conventional composites with a smooth, lustrous surface similar to tooth enamel less susceptible to plaque retention and discoloration. Filler particle size: colloidal silica particles whose average diameter is 0.01 to 0.04 μm. Filler content: approximately 35% to 60% by weight.  Properties: ✓Some of their physical and mechanical characteristics are inferior. ✓Clinically highly wear resistant. ✓Low modulus of elasticity may allow microfill composite restorations to flex during tooth flexure, better protecting the bonding interface. This makes micro-fill composites an appropriate choice for restoring Class V cervical lesions or defects in which cervical flexure can be significant (e.g., bruxism, clenching, stressful occlusion).  3. Hybrid composite: Hybrid composites were developed in an effort to combine the favorable physical and mechanical properties characteristic of macrofill composites with the smooth surface of the microfill composites. Filler size: mixture of microfiller and small filler particles that results in a considerably smaller average particle size (0.4–1 μm) than that of conventional. Filler content: 75-85% by weight  Properties: ✓Because of the relatively high content of inorganic fillers, the physical and mechanical characteristics are generally superior to those of conventional composites. ✓Classic versions of hybrid materials exhibit a smooth “patina-like” surface texture in the finished restoration. Nanohybrid composites: these are newer versions of hybrid composites contain ultra-small nanofillers, resulting in superior characteristics. 4. Nanofill composites Filler particles size are extremely small (0.005–0.01 μm). Consequently, high filler levels can be generated in the restorative material, which results in: 1. Good physical properties 2. Improved esthetics. 3. The small primary particle size also makes nanofills highly polishable  Nanofill and Nanohybrid composites are the most popular composite restorative materials in use. These composites have almost universal clinical applicability Wear Comparison: Porous friable nanoclusters Lightly sintered Hybrid-wear True Nano wear III. Classification (cont.) b. According to handling ccc Flowable Packable  1.Packable composite Their development is an attempt to accomplish Easier restoration of a proximal contours and contacts and Because of the increased viscosity, it is typically more difficult to attain optimal marginal adaptation.  2. Flowable composite Generally, have lower filler content and consequently inferior physical properties such as: 1. lower wear resistance. 2. Lower strength. 3. They also exhibit much higher polymerization shrinkage. WHY? Due to decreased filler loading thus Decrease viscosity Decrease mechanical properties Increased polymerization shrinkage.  Uses: 1. Pit-and-fissure sealants, 2. Marginal repair materials. 3. First increment placed as a stress-breaking liner under posterior composites. 4. First small increments in the proximal box of Class II restoration in an effort to improve marginal adaptation. IV. Properties: 1. Linear Coefficient of Thermal Expansion. 2. Water sorption. 3. Wear Resistance. 4. Surface Texture. 5. Radiopacity. 6. Modulus of Elasticity 7. Polymerization.  1. Linear Coefficient of Thermal Expansion the rate of dimensional change of a material per unit change in temperature. The LCTE of modern composites is approximately three times that of tooth structure. Bonding a composite to etched tooth structure reduces negative effects due to difference between the LCTE of the tooth structure and that of the material IV. Properties: 1. Linear Coefficient of Thermal Expansion. 2. Water sorption. 3. Wear Resistance. 4. Surface Texture. 5. Radiopacity. 6. Modulus of Elasticity 7. Polymerization.  2. Water sorption: Water sorption is the amount of water that a material absorbs over time per unit of surface area or volume. Materials with higher filler contents exhibit lower water absorption values than materials with lower filler content. Incompletely cured composites exhibit higher water absorption values causing bulk discoloration. IV. Properties: 1. Linear Coefficient of Thermal Expansion. 2. Water sorption. 3. Wear Resistance. 4. Surface Texture. 5. Radiopacity. 6. Modulus of Elasticity 7. Polymerization.  3. 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 bolus, and such items as toothbrush bristles and toothpicks. Wear resistance of contemporary composite materials is generally good. IV. Properties: 1. Linear Coefficient of Thermal Expansion. 2. Water sorption. 3. Wear Resistance. 4. Surface Texture. 5. Radiopacity. 6. Modulus of Elasticity 7. Polymerization. 4. Surface Texture Surface texture is the smoothness of the surface of the restorative material. Nanohybrid and Nanofill composites also provide surface textures that are polishable, esthetically satisfying, and compatible with soft tissues. So, esthetical and biocompatible. IV. Properties: 1. Linear Coefficient of Thermal Expansion. 2. Water sorption. 3. Wear Resistance. 4. Surface Texture. 5. Radiopacity. 6. Modulus of Elasticity 7. Polymerization.  5. Radiopacity Esthetic restorative materials must be sufficiently radiopaque so that the radiolucent image of recurrent caries around or under a restoration can be seen more easily in a radiograph. Most composites contain radiopaque fillers such as barium glass to make the material radiopaque. IV. Properties: 1. Linear Coefficient of Thermal Expansion. 2. Water sorption. 3. Wear Resistance. 4. Surface Texture. 5. Radiopacity. 6. Modulus of Elasticity 7. Polymerization.  6. 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. Clinical application: This is particularly true for Class V restorations in teeth experiencing heavy occlusal forces, where stress concentrations exist in the cervical area. Such stress can cause tooth flexure that can disrupt the bonding interface. Using a more flexible material such as a microfill composite allows the restorations to bend with the tooth, better protecting the bonding interface Abfraction A 17-year-old girl presents to the Dental Clinic complaining of black spot on facial surface of upper front tooth. Clinical examination reveals small size cervical caries in teeth # 22. Class V composite restoration is the treatment of choice. Which composite is the best used? Nanofilled/Nanohybrid Thank You