optical , electro chemical and biological properties

What is poly chromatic and what type of light has this?

Mixture of wavelengths, found in white light

What is the visible range for light?

400 - 700 nm

What is the visible range for violet?

400 nm

What is the visible range for dark red light?

700 nm

What is enamels refraction index?

1.65

When light strikes enamel it maybe reflected, refracted, absorbed, or transmitted what do each of those mean?

Reflected: bounces off the surface

Reflected: changes directed

Absorbed: taken up by the material

Transmitted: passes through the material

What are the three dimensions of color?

Hue - chroma - value

What is hue?

What color is it ( yellow, blue, green,or red)

What is chroma?

How strong is the color

What is value? And what does higher and lower mean?

Is the color lighter or darker

Higher value is lighter and lower value means darker

Which one is more critical in a dental shade matching? (Hue, chroma, or Value)

Value

How should you perform shade matching?

Under 2 different light sources

What is fluorescence?

When a material can absorb shorter wavelengths but emit longer wavelengths

What is the passage of light in opacity?

No passage of light

What is the passage of light in translucency?

Allows light to enter and scatter

Example of translucent dental materials?

Ceramics - resin composites - acrylic

What is transparency?

Allow light to pass through with little distortion

What is metamerism?

When two restorations match under one light source but differ under another

What is biocompatibility?

Ability of a material to perform with an appropriate reaction from the host

What are the 2 types of allergic reactions?

Type I: immediate reaction

Type IV: delayed reaction

Common types of allergic reactions in a dental settling?

Nickel, amalgam (contact dermatitis), and eugenol in Zoe (hypersensitivity or mucosal irritation)

When do local reactions occur?

Substances released from dental materials can affect tissues at or near the site of contact

How long acute systemic toxicity occur?

Up to 24 hours

How long does subacute systemic toxicity occur?

Up to 3 months

How long does chronic systemic toxicity last?

3 months or more

What is tarnish?

Surface discoloration or loss of metals original luster

What is tarnish caused by?

Thin surface films such as sulfides, oxides, or chlorides.

What is corrosion

Deterioration of metal due to its reaction to the environment

What is chemical dry corrosion?

It occurs in the absence of water, direct chemical combination of metallic and nonmetallic elements through oxidation reactions

Examples of chemical dry corrosion

Discoloration of silver by sulfur - oxidation of silver copper alloy

What is electrochemical (wet) corrosion?

Requires water or another fluid electrolyte and an electrical current

Example of electrochemical corrosion?

. Galvanic corrosion because the anode would be the amalgam restoration, cathode would be gold alloy restoration and electrolytes would be saliva

4 causes of corrosion?

Dissimilar metals, single metallic restoration heterogenous composition surfaces stress corrosion

5 ways to protect against corrosion?

Use similar metals, increase noble metal count, passivation, polishing, surface coating