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Questions and Answers
What type of laser can be used in both clinical and lab settings?
What type of laser can be used in both clinical and lab settings?
Polywave light curing units only emit blue light.
Polywave light curing units only emit blue light.
False
What is the purpose of a soft start in polymerization?
What is the purpose of a soft start in polymerization?
To slow down polymerization and give more time for radicals to form polymer chains.
The internal housing of a curing tip has a diameter that is smaller than the __________ housing.
The internal housing of a curing tip has a diameter that is smaller than the __________ housing.
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Match the light curing modes to their descriptions:
Match the light curing modes to their descriptions:
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Which polymerization mode gradually increases intensity up to 1000?
Which polymerization mode gradually increases intensity up to 1000?
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Cordless light curing units do not require charging.
Cordless light curing units do not require charging.
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What effect does the temperature in a patient's mouth have on polymerization?
What effect does the temperature in a patient's mouth have on polymerization?
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A polywave LED light may not be ideal for curing because __________ can interfere with the homogeneity of the light.
A polywave LED light may not be ideal for curing because __________ can interfere with the homogeneity of the light.
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What type of light curing unit may only use blue-based mono wave light?
What type of light curing unit may only use blue-based mono wave light?
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Which photoinitiator is commonly used for both aesthetic applications and requires a tertiary amine to start the reaction?
Which photoinitiator is commonly used for both aesthetic applications and requires a tertiary amine to start the reaction?
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What is the purpose of a radiometer in the context of light curing units?
What is the purpose of a radiometer in the context of light curing units?
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Irgacure 819 is activated by blue light only.
Irgacure 819 is activated by blue light only.
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What is the wavelength range of light that camphorquinone is sensitive to?
What is the wavelength range of light that camphorquinone is sensitive to?
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The degree of conversion for a well-polymerized composite can reach 100%.
The degree of conversion for a well-polymerized composite can reach 100%.
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The polymerization process converts a __________ into a polymer.
The polymerization process converts a __________ into a polymer.
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What does the C-factor represent in dental composite applications?
What does the C-factor represent in dental composite applications?
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Match the following light curing units with their characteristics:
Match the following light curing units with their characteristics:
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Oxygen inhibition in polymerization can result in a ______________ appearance of the restoration.
Oxygen inhibition in polymerization can result in a ______________ appearance of the restoration.
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Which photoinitiator is specifically noted for being unstable and sensitive to light?
Which photoinitiator is specifically noted for being unstable and sensitive to light?
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Match each curing mode with its characteristic:
Match each curing mode with its characteristic:
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What impact does distance have on irradiance during light curing?
What impact does distance have on irradiance during light curing?
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The refractive index of the organic matrix should ideally match the refractive index of the filler particles for efficient polymerization.
The refractive index of the organic matrix should ideally match the refractive index of the filler particles for efficient polymerization.
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What is the maximum effective wavelength for polymerization using the most common photoinitiator?
What is the maximum effective wavelength for polymerization using the most common photoinitiator?
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Using a plastic barrier with loose seams can lead to a loss of irradiance.
Using a plastic barrier with loose seams can lead to a loss of irradiance.
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The __________ is the energy density of a light source, measured over time.
The __________ is the energy density of a light source, measured over time.
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Name one common type of bacteria involved in caries formation.
Name one common type of bacteria involved in caries formation.
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Which type of light curing unit has the advantage of a bulb but needs maintenance and replacement?
Which type of light curing unit has the advantage of a bulb but needs maintenance and replacement?
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The __________ phase is when the polymer chain starts to form and molecules can no longer move.
The __________ phase is when the polymer chain starts to form and molecules can no longer move.
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Plasma curing units can effectively cure materials thicker than 2mm.
Plasma curing units can effectively cure materials thicker than 2mm.
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What should be done to ensure the efficiency of light cure?
What should be done to ensure the efficiency of light cure?
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What added component allows bulk filled composites to be cured without co-initiators?
What added component allows bulk filled composites to be cured without co-initiators?
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Temperature increase during curing can potentially cause damage to healthy pulp tissue.
Temperature increase during curing can potentially cause damage to healthy pulp tissue.
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High irradiance curing units generally require a minimum __________ for effective curing.
High irradiance curing units generally require a minimum __________ for effective curing.
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What can help manage polymerization shrinkage during composite curing?
What can help manage polymerization shrinkage during composite curing?
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Improper bonding procedures can lead to __________ fractures.
Improper bonding procedures can lead to __________ fractures.
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Which photoinitiator is lighter in pigment compared to camphorquinone and activates in violet light?
Which photoinitiator is lighter in pigment compared to camphorquinone and activates in violet light?
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Match the following terms to their definition:
Match the following terms to their definition:
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Match each light characteristic with its effect on the curing process:
Match each light characteristic with its effect on the curing process:
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Study Notes
Photopolymerization
- Photoinitiators are present in dental resins, particularly composites.
- Violet light (380-420 nm) is a popular choice for developing composite materials.
- Blue light (420-490 nm) is another option, and light-cure methods cover both spectra.
- Lucirin TPO is the most common photoinitiator in Norridge Group 1.
- It has a peak absorption spectrum at 381-390 nm.
- Norridge Group 2 commonly uses camphorquinone (CQ).
- CQ is typically yellow and requires a tertiary amine for activation
- CQ has a peak absorption at 468 nm.
- PPD-1 can belong to both groups and has a peak absorption at 398 nm.
- Photoinitiators (like Lucirin TPO) can enhance polymerization of composite materials, enabling application of thicker layers more quickly.
- Some photoinitiators (such as CQ) don't necessarily require co-initiators in the same ways as other types.
Effectiveness of Polymerization
- The type and concentration of fillers, monomers, and other components in resin-based composite influence light transmission, absorption, reflection, and scattering.
- Refractive index of resin components affect how light penetrates, which can alter the rate and quality of polymerization.
- Matching refractive indices of resin components is crucial but not necessarily perfect, leading to less discrepancy.
- A good refractive index allows light to penetrate the composite with greater depth.
- Polymerization can be affected by exposure time to light.
- Exposure time can influence the final quality and properties of the polymerized material.
Factors Related to Light Curing Units (LCUs)
- The spectral range of light emitted by the LCU is crucial.
- An LCU's light spectrum must match the photoinitiator's absorption spectrum for optimal polymerization.
- Irradiance is the power density (or intensity) of light.
- It is represented by total power of light divided by the area of guide.
- This impacts curing time.
- Radiant exposure is the energy density or total energy from light exposure. It's calculated by multiplying irradiance by exposure time.
Factors Related to Light Curing Units (LCUs) (cont.)
- Exposure time required for polymerization
- Size, tip geometry, and the beam profile of LCUs impact how evenly the light is distributed across the surface.
- The refractive index of the filler particles in the composite material plays a crucial role in polymerization efficiency.
- The match between the refractive indices of the filling material and the composite should be considered during curing to avoid any irregularities in shade or finish.
- Proper matching of the refractive indices can lead to better polymerization and avoid potential irregularities in shade or finish.
Additional factors
- Different types of curing units (e.g., halogen, plasma, LED) that may require specific filtering of light to ensure proper activation of photoinitiators.
- Potential for temperature increase, causing damage to the pulp or surrounding tissue.
- Inhibitors, such as BHT and PI, are required against ambient light exposure.
- The correct shade/color of restoration materials must match the surrounding teeth, and curing should follow manufacture instructions for optimal results.
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Description
This quiz explores the role of photoinitiators in dental composite resins, specifically focusing on their absorption spectra and effectiveness in polymerization. Learn about the commonly used photoinitiators like Lucirin TPO and camphorquinone, and discover how light spectra influence the curing process.
