Operative Dentistry: Composite Restoration

Composite Restoration (2)

• Batterjee Medical College, operative dentistry division presentation
• Key learning objectives focus on advantages/disadvantages, indications/contraindications, and clinical techniques
• Reference: Art and science of operative dentistry 6th edition, chapter 8, page 216

Polymerization

• Chemical reaction converting low molecular weight monomer molecules to high molecular weight polymer chains
• Two methods exist: self-cured and light-cured (using visible light)

Light Curing

• Diketone initiators (e.g., camphoroquinone) are activated by wavelengths in the 370-500nm range, peaking at 468nm (blue region of the visible spectrum)
• Upon irradiation, initiators dissociate into radicals

Curing Devices

• Quartz, tungsten halogen light-curing systems efficiency decreases with time
• Plasma arc curing systems offer high intensity and speed, but also significantly increase stresses from heat generation and polymerization shrinkage
• Light-emitting diodes (LEDs) are the predominant curing method today, due to their increased efficiency, portability, and durability

Polymerization Shrinkage

• Composite materials shrink during polymerization (volume change)
• This shrinkage can lead to gaps at the tooth restoration interface if the bond strength is insufficient
• Controlling shrinkage involves proper adhesive use, increment thickness, and increment configuration during insertion

C-factor

• Ratio of bonded surfaces to unbonded surfaces in a tooth preparation
• The higher the C-factor, the greater the potential for bond disruption from polymerization shrinkage
• Class IV restorations (one bonded surface, four unbonded) have a lower C-factor (low risk), while Class I restorations (five bonded surfaces, one unbonded) have a higher C-factor (higher risk)

Reducing Internal Stresses

• Use oblique incremental additions to reduce polymerization shrinkage effects
• Employ stress-breaking liners (e.g., filled dentinal adhesives, flowable composites, or RMGI)

Advantages of Composite Restorations

• Bonded to tooth structure, leading to good retention, low microleakage, and minimal staining.
• Increased strength of remaining tooth structure
• Esthetic restorations
• Conservative in tooth preparation
• Insulating due to low thermal conductivity
• Widely used and readily repairable

Disadvantages of Composite Restorations

• Gap formation, often on root surfaces, possibly due to the forces of polymerization shrinkage, or improper insertion
• More technique-sensitive and complex requiring appropriate isolation and bonding technique
• Can exhibit greater occlusal wear in areas of high occlusal stress or if all occlusal contacts are on the restoration

Indications for Composite Restorations

• Direct restorations (Classes I, II, III, IV, V, and VI)
• Foundations or core buildups
• Sealants and preventive resin restorations (PRR)
• Esthetic procedures (full and partial veneers, contour modifications, diastema closures)
• Periodontal splinting

Contraindications for Composite Restorations

• If the operating site cannot be isolated from oral fluids
• If all occlusal contacts are on the restoration
• Composite restoration extensions on root surfaces may exhibit gap formation

Clinical Technique

• Local Anesthesia
• Operating site preparation
• Shade selection & confirmation
• Pre-operative occlusion assessment
• Isolation
• Bonding
• Incremental packing
• Finishing & polishing

Shade Selection

• Shade selection should be performed before prolonged drying to avoid dehydration-related shade changes
• Bleaching, if performed, should be completed before restorations
• Employ proper lighting (natural light preferred) and color corrected operating lights
• Use a shade guide, and confirm selection by placing a small amount of the material directly onto the tooth

Shade Guide

• Most manufacturers provide shade guides for their materials which may not be interchangeable
• Manufacturers often cross-reference their shades with the Vita Classical shade guide, a widely used standard

This quiz focuses on the key concepts of composite restoration in operative dentistry, particularly the advantages, disadvantages, and clinical techniques. It includes insights from the 'Art and Science of Operative Dentistry' 6th edition. Knowledge of polymerization and light curing methods will also be assessed.