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Dental Materials > Polymerization & Curing Lights > Flashcards

Polymerization & Curing Lights Flashcards

1
Q

What does a photo-initiator in resin do?

A
  • Absorbs photon energy
  • Combines with activator (amine)
  • Creating free radicals
  • Initiates polymerization via monomer (Bis GMA)
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2
Q

What is Comphorquinone?

A
  • Photoinitiator
  • Most common photo-absorbing material
  • Maximum sensitivity is in the BLUE RANGE
  • 400-520 nm
  • Peak at 468 nm
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3
Q

What is the first step of Polymerization?

A

Initiation

  • Production of reactive free radicals
  • Chemical, light, heat
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4
Q

What is the second step of Polymerization?

A

Propagation

  • Monomer units
  • Polymer network
  • 50-60% degree of conversion
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5
Q

What is the last step of Polymerization?

A

Termination

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6
Q

What are some different energy sources for curing lights? Which one do we use?

A
  • Halogen
  • Plasma-arc
  • Argon laser
  • LED (WHAT WE USE!)
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7
Q

What does LED stand for?

A

Light Emitting Diode

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8
Q

What is the spectrum of an LED curing light for camphorquinone?

A

430-490 nm

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9
Q

What are some perks of using an LED curing light?

A
  • Long lasting light source
  • Minimal bulb aging
  • Shock resistant
  • Less lateral heat production
  • Efficient
  • Cordless
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10
Q

What are 2 different photoinitiators other then CQ?

A

PPD & TPO - VIOLET SPECTRUM

They use LESS yellow than comphorqinone

Less the CQ… 398 nm and 381 nm respectively

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11
Q

What is neat about third generation LED lights?

A
  • They are Dual-Emission Spectrum

- Reportedly cures all photo-initiated materials

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12
Q

What is Attenuation of Violet Light?

A
  • Decreases as thickness of composite increases

- Fill particles tend to scatter more light at shorter wavelengths

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13
Q

What type of curing light do you use?

A
  • Dual-Spectrum LED
  • Bluephase G2 by Ivoclar
  • 10 mm diameter fiber-optic light guide
  • Soft start polymerization available
  • Low or high setting (650 or 1200 mW)
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14
Q

What are the effects of INCREASED light exposure?

A
  • Increased depth of cure
  • Increased conversion (polymerization)
  • Increased hardness
  • Only up to a threshold…
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15
Q

What are the effects of DECREASED light exposure?

A

Inadequate polymerization

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16
Q

What are some consequences of inadequate polymerization?

A
  • Reduced physical properties
  • Decreased color stability
  • Increased wear
  • Increased Solubility
  • Leaching of unreacted monomer
  • Increased toxicity
17
Q

What is light attenuation?

A

Irradiance decreases with depth

Light gets absorbed and scattered from colored molecules, filler particles, and polymerized polymer

18
Q

What factors affect HOW LONG it takes to cure an increment of composite?

A

Depends on…

  • Radiant exposure (energy density - curing light strength)
  • Distance from composite
  • Collimation of light (light waves running parallel)
  • Angulation
  • Spectral emission
  • Attenuation of light
  • Composite Type (Opacity, shade, photoinitiator)
19
Q

Larger tips of curing lights have low or high irradiance?

A
  • Low (less concentrated)
20
Q

Smaller tips of curing lights have low or high irradiance?

A
  • High (more concentrated)
21
Q

Does the shade of composite effect energy transmission?

A

Yes!

Darker and opaque shades impede energy transmission

22
Q

Does the angle you hold the curing light matter?

A

Yes!

Ideally you should hold it at 0 degrees

23
Q

Why have blue and violet on our curing lights at Dunn?

A

Covers multiple photoinitiators

We call this multispectrum

1200 mW on high

510 mW on low

24
Q

You will want to INCREASE your curing time for the following factors…

A
  • Lower irradiances - (less concentrated)
  • Darker shades
  • Greater distances
  • Poor collimation (beams running parallel)
  • Poor angulation
25
Q

You will want to DECREASE your curing time for the following factors…

A
  • Higher irradiances - (more concentrated)
  • Lighter shades
  • Close distance
  • Good collimation (beams running parallel)
  • Good angulation
26
Q

What is the percentage of composite shrinkage after curing?

A

1-6%

  • Microleakage
  • Staining
  • Post-op sensitivity
27
Q

What is the primary reason for replacement of composites?

A

Secondary caries

28
Q

What do studies show about “Soft Start” curing technique?

A
  • May not be clinically significant

- More studies needed

29
Q

Is there a significant risk of retinal damage due to blue light?

A

Yes!

30
Q

What device can you use to measure if a curing light is working correctly?

A

Radiometer - $100

Dental Materials (9 decks)

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