5 Composite Restoration and Polymerization Overview

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Questions and Answers

What should be avoided when cleaning the operating site prior to a composite restoration?

Acid-etch solutions

Water-based cleansing agents

Cotton rolls

Prophy pastes with flavoring agents (correct)

Which is NOT a contraindication for using direct composite restorations?

Gap formation at the composite and root junction

All occlusion on the restorative material

Inability to isolate the operating site

Composite restoration extensions on the enamel (correct)

At what point should shade selection for composite restorations occur?

After the bonding process

During the finishing and polishing phase

Before prolonged drying of teeth (correct)

Immediately after local anesthesia administration

Which attribute of color indicates how rich or vivid a color appears?

Chroma Signup and view all the answers

What is the effect of using poor lighting during shade selection?

It may cause color misjudgment Signup and view all the answers

Which procedure contributes to a more comfortable composite restoration experience?

Using local anesthesia Signup and view all the answers

What can be a result of dehydrating teeth prior to shade selection?

Teeth may lose their translucency Signup and view all the answers

What procedure should be performed two weeks prior to placing restorations if bleaching is contemplated?

Bleaching of teeth Signup and view all the answers

What is the C-factor of a Class I restoration?

5 Signup and view all the answers

Which technique can help reduce internal stresses in restorations with a high C-factor?

Oblique incremental additions Signup and view all the answers

What is a disadvantage of composite restorations compared to amalgam?

Greater occlusal wear under stress Signup and view all the answers

What is one of the advantages of composite restorations?

They are repairable Signup and view all the answers

In which scenario would a filled dentinal adhesive be particularly useful?

As a stress-breaking liner Signup and view all the answers

Which of the following restorations can composites be used for?

All Class restorations (I, II, III, IV, V, VI) Signup and view all the answers

What is a factor that can lead to gap formation in composite restorations?

Forces of polymerization shrinkage exceeding adhesive bond strength Signup and view all the answers

Which characteristic of composites contributes to their use as an aesthetic material?

Translucency and color matching Signup and view all the answers

What is the primary function of diketone initiators in the curing process of composites?

To initiate the polymerization reaction upon irradiation Signup and view all the answers

Which method of polymerization creates high-intensity curing and is known for speed?

Plasma arc curing systems Signup and view all the answers

What effect does polymerization shrinkage have on composite restorations?

May create gaps at the tooth restoration interface Signup and view all the answers

How can polymerization shrinkage be controlled during the composite application?

By adjusting the adhesive used Signup and view all the answers

What is the C-factor in the context of composite restorations?

The ratio of bonded surfaces to free surfaces in a tooth preparation Signup and view all the answers

Which curing system is noted to decrease in efficiency over time?

Quartz, tungsten halogen light-curing systems Signup and view all the answers

What occurs upon irradiation of diketone initiators during the curing process?

They dissociate into radicals Signup and view all the answers

What is a disadvantage of using plasma arc curing systems?

Increased heat generation and polymerization shrinkage Signup and view all the answers

What lighting conditions are recommended for accurate shade selection in the absence of natural daylight?

Color corrected operating lights or ceiling lights Signup and view all the answers

Why should the dental operating light be moved away during shade selection?

To decrease the light intensity and observe shadows Signup and view all the answers

Which feature distinguishes enamel shades from dentin shades in composite materials?

Enamel shades are more translucent. Signup and view all the answers

What is the primary purpose of using a shade guide during dental procedures?

To select appropriate materials for dental restorations Signup and view all the answers

How long should shade selection be attempted before eye fatigue makes it difficult to distinguish colors?

30 seconds Signup and view all the answers

What technique can be used to rest the eyes after prolonged shade selection?

Look at a blue or violet object Signup and view all the answers

What is the role of placing a small amount of material of the selected shade on the tooth?

To assess the accuracy of the selected shade Signup and view all the answers

What is a common mistake when using shade guides from different manufacturers?

Shade guides may not accurately reflect colors across manufacturers. Signup and view all the answers

Study Notes

Composite Restoration (2)

Composite restorations are superior to amalgam restorations in terms of aesthetics, minimal depth of tooth removal, and high resistance
Composite restorations bond to tooth structure, thus decreasing microleakage, providing high retention and minimal interfacial staining
Composite restorations are esthetic and versatile, and their use is universal
Composite restorations are repairable
Composite restorations have a low thermal conductivity, acting as an insulator

Polymerization

Polymerization is a chemical reaction where low molecular weight monomers are converted into high molecular weight polymers
Two methods of polymerization are self-cured and light-cured, utilizing visible light
Diketone initiators, such as camphoroquinone, are activated by wavelengths between 370-500 nm with a peak at 468 nm, initiating a radical chain reaction of monomer polymerization

Curing Devices

Quartz, tungsten halogen light-curing systems decrease efficiency over time
Plasma arc curing systems are high-intensity, high-speed curing systems, but they generate significant stresses due to heat generation and polymerization shrinkage
LED light-curing units are more efficient, portable, and durable

Polymerization Shrinkage

Composite materials shrink during polymerization, leading to polymerization shrinkage
Shrinkage can cause gaps at the tooth restoration interface if not controlled
Controlling polymerization shrinkage is done by:
- Using appropriate adhesives
- Adjusting the amount of composite used (increment thickness)
- Using proper increment configuration
High C-factor restorations (high ratio of bonded surfaces to unbonded) are more prone to polymerization shrinkage

C-Factor

C-factor is the ratio of bonded to unbonded surfaces in a tooth preparation
Higher C-factor indicates a greater risk of bond disruption from polymerization shrinkage
Class IV restorations (one bonded surface, four unbonded) have a low risk of shrinkage, while Class I restorations (five bonded surfaces, one unbonded) have a high risk

Internal Stresses

Internal stresses from polymerization shrinkage can be reduced by using oblique incremental additions or stress-breaking liners (such as filled dentinal adhesive, flowable composite, or RMGI)

Advantages/Disadvantages

Advantages*
High retention and strength
Low microleakage
Minimal interfacial staining
Esthetic properties
Effective thermal insulation
Repairable
Disadvantages*
Potential for a gap formation, especially on root surfaces, due to polymerization shrinkage forces exceeding the initial bond strength to the dentin
Technique sensitivity compared to amalgam restorations (more difficult, time-consuming, and costlier) for gap formation to occur
Operative site must be properly isolated and bonded, and bonding technique is crucial and essential
Increased potential for occlusal wear in areas of high stress during stress or contacts

Indications/Contraindications

Indications*
Direct restorations (Classes I-VI)
Foundations or core buildups
Sealants and preventive resin restorations
Esthetic enhancement procedures (partial veneers, full veneers, tooth contour modifications, diastema closures)
Periodontal splinting
Contraindications*
Oral contamination and fluids can prohibit isolation or bonding
If occlusion entirely affects the restorative material, other materials may be necessary to prevent gap formation.
Composite restorations exceeding the root surfaces may result in gap formation
Composite restorations are not appropriate for locations prone to high stress

Clinical Technique

Local anesthesia to create comfort, interrupted procedure, and reducing salivation
Preparation of operative site, including removing plaque, pellicle, stains, and calculus
Shade selection, particularly before prolonged drying as teeth dehydrate, decrease in translucency, and become lighter in shade
Pre-operative occlusion assessment using articulating paper
Isolation using rubber dam or cotton rolls to prevent contamination
Bonding, incremental packing, and finishing and polishing step-by-step technique

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Description

This quiz explores the techniques and benefits of composite restorations in dentistry, highlighting their aesthetic advantages and bonding properties. Additionally, it covers the process of polymerization, including methods and curing devices used in dental applications. Test your understanding of these important concepts in restorative dentistry.