Lecture 10 Flashcards
3 Dimensions of Color:
Hue chroma, and value
Value:
lightness or darkness, grayscale
Chroma:
saturation of color
Color:
A phenomenon of light or visual perception that allows the differentiation of otherwise identical objects
T or F? The exposure of one color to different light sources can change our perception of that color.
T
What does color depend upon?
Observer, Object, and Light source
In what way is energy needed to perceive color?
We need light energy (wavelength) to see color
What provides the color to the tooth?
dentin
How does the enamel contribute to the color of the tooth?
modifies color, translucent
Which is opaque and which is translucent, bw dentin and enamel?
enamel: translucent, dentin: opaque
2 main light sources in dentistry:
incandescent and fluorescent
What color does incandescent light emit?
higher conc of yellow than blue and blue-green
What does fluorescent light emit higher amounts of?
blue waves
What is the ideal light source for choosing color shade?
color corrected fluorescent
Factors affecting how we see color:
color blindness, color adaption, metamerism
color adaption is aka:
negative afterimage
What is color adaptation?
Color vision dec rapidly, color bc less saturated until it appears almost gray
What is metamerism?
Color of object exposed to different light sources will be perceived differently
How to avoid metamerism?
use multiple light sources
Where is it good to take the pt here to select the color shade:
the window, this is a balanced light source
Shade selection:
beginning of appt., prior to RD isolation, under balanced lighting , mock up necessary
Why can’t you choose color properly after RD placement?
teeth loose moisture and appear brighter
What is a mock up?
polymerize restorative material on the tooth with no bonding agent, half the curing light time, look at under list conditions
When is a mock up recommended?
always
Factors affecting shade selection:
light source, office background, Pt surrounding colors, time of day, distance and angle to pt, condition of the teeth
Will the value, chroma, or hue of a tooth change after RD placement?
Value
best position to be to pt:
Arm length, best image on retina
Primary division of shade guide:
hue
A:
Reddish brown
B:
reddish-yellow
C
grey
D:
Reddish grey
T or F? The tooth structure can change the color of the composite.
T
When will a Class III bc Class IV?
If it will undermine the incised edge
Prep for Class IV:
bevel or remove the rest of the lesion
When to use mechanical retention?
NEVER! only in lab w plastic tooth
Facial bevel:
Long scalloped
Lingual bevel:
short, not scalloped
Techniques for Class iV:
free hand and lingual matrix
What is the matrix we use made of?
silicone putty
Reason for the facial scallop:
esthetics
Why use Sof-Lex discs?
to roughen the tooth for better retention
Bur for beveling:
flame or diamond bur
Contact should be __ mm wide incised, gingivally:
1-2mm
What type of restoration are we doing?
MIFL
What type of shine do we want?
high shine
How to prevent discoloration of the composite?
remove pencil marks and clean gloves
What teeth will be used to make a silicone matrix?
7-10
RD from here to here:
C to C (Tooth #8 is our tooth)
When to remove mylar strips:
after curing the bonding agent, polymerize from facial, remove, cure from lingual
Typeof matrix we are using
Condensation silicon matrix
Type of Resin we are using:
Natural Look
