Operative Dentistry Chapter 8 Quiz

Composite Restoration (2)

• Batterjee Medical College, a college for Science and Technology, is the source of the presentation.
• The presenter, Dr. Rehab Alwakeb from Operative Dentistry, discusses composite restorations.
• Reference material is the Art and Science of Operative Dentistry 6th edition, chapter 8, page 216.
• Learning Objectives (ILOs) include determining composite restoration advantages, disadvantages, indications, and contraindications.
• The second ILO is determining the clinical technique for composite application.

Properties (Continuation)

• Polymerization is a chemical reaction changing low molecular weight monomers into high molecular weight polymers.
• The two polymerization approaches are self-cured and light-cured. Light curing utilizes visible light.

Light Curing

• Camphoroquinone is a type of diketone photo-initiator activated by wavelengths between 370-500 nm, and peaking at 468 nm (blue light).
• Upon irradiation, it dissociates into radicals.

Curing Devices

• Quartz, tungsten halogen light curing systems decrease in efficiency over time.
• Plasma arc curing systems offer high-intensity and speed compared to quartz/tungsten systems.
• Heat generation and polymerization shrinkage increase stress.
• Light-emitting diodes (LEDs) are the predominant approach today; they are more efficient, portable, and durable.

Polymerization Shrinkage

• Composite materials shrink during polymerization (shrinkage/volume change).
• This shrinking can produce gaps at the tooth restoration interface if the polymerization shrinkage force is greater than the bond strength of the composite to dentin.
• Controlling polymerization shrinkage: appropriate use of adhesives, incremental composite thickness, and increment configuration.

C-factor

• The C-factor is the ratio of bonded surfaces to unbonded surfaces after preparing a tooth.
• A higher C-factor indicates a greater potential for disruption from polymerization shrinkage.
• Class IV restorations (one bonded, four unbonded) have a low risk of shrinkage issues (C-factor of 0.25), while Class I restorations (five bonded, one unbonded) have a higher risk (C-factor of 5).

Internal Stress Reduction

• High internal stress in restorations due to potentially high polymerization shrinkage (Class I preparations) can be reduced.
• Two approaches: oblique incremental additions and the use of stress-breaking liners (filled dentin adhesive, flowable composite, RMGI).

Advantages

• Composite restorations are bonded to tooth structure, yielding better retention, lower microleakage, minimal interfacial staining, and increased strength compared to amalgam restorations.
• They are more aesthetic and conservative, so less tooth structure removal is necessary.
• They have low thermal conductivity and are universally used.
• Composite restorations are repairable.

Disadvantages

• Potential gap formation, most frequently on root surfaces, due to polymerization shrinkage exceeding initial bond strength or improper insertion.
• Technique is more sensitive, time-consuming, and costly compared to amalgam restorations.
• Operating site isolation and proper bonding are crucial.
• High occlusal stress areas may exhibit wear if restorative material is subject to significant occlusal forces.

Indications

• Direct restorations—Class I, II, III, IV, V, and VI.
• Foundations or core buildups.
• Sealants and preventive resin restorations (PRR)
• Aesthetic enhancements: partial/full veneers, tooth contour modifications, and diastema closures.
• Periodontal splinting.

Contraindications

• If operating site isolation is not possible due to oral fluids.
• If all occlusal forces are on the restorative material.
• Composite restorations on the root surface might have a gap at the junction. RMGI restorations might be preferred instead.

Clinical Technique

• Local Anesthesia

  • Contributes to a more comfortable and uninterrupted procedure, marked reduction in salivation.

• Preparation of Operating Site

  • Removal of plaque, pellicle, superficial stains, and calculus. Removal of materials containing flavoring agents, glycerin or fluoride, as these may interfere with acid-etch bonding.

• Shade Selection

  • Performed before prolonged tooth drying to avoid lighter shades. Done before bleaching. Appropriate lighting is necessary.

• Shade Guide

  • Specific to individual manufacturers, not interchangeable. May cross-reference with Vita Classical shade guide. Some now offer very light shades because bleaching is common.
  • Selection technique: rapid selection to avoid eye fatigue. If necessary, operator should rest the eyes looking at complementary colours (blue/violet) to revitalize and re-sensitize color receptors.
  • Confirmation: Small amount of material on the tooth area, close to the site, and cured provides an accurate assessment.

• Pre-operative Occlusion Assessment

  • Identification of occlusal contacts on the tooth(s) to be restored. Assessment also includes occlusal contacts on adjacent teeth. Use articulating paper to establish, and correct proper occlusal contact on the restoration.

• Isolation

• Isolation of the operative site, usually with a rubber dam or cotton rolls, is essential for proper bonding to succeed. Saliva contaminating the etched enamel or dentin would significantly lower bonding success. Further, contaminating the composite material has the potential for lower physical durability.

• Bonding

• Incremental Packing

• Finishing and Polishing

Test your knowledge on composite restorations as discussed in chapter 8 of Art and Science of Operative Dentistry. This quiz covers the advantages, disadvantages, clinical applications, and polymerization techniques involved in composite restorations. Dive into the specifics of light curing and the properties of materials used in operative dentistry.