Shade selection for fixed partial denture

1. Shade Selection & Lab
Instruction in FPD
DEPT.OF PROSTHODONTICS & CROWN & BRIDGE
North Bengal Dental College & Hospital

2. Introduction
To provide aesthetic restorations to the patients,the dentist
must understand the scientific as well as artistic basis of
shade selection.To accomplish this,a through knowledge
of the concepts of colour & light is necessary with clear
communication to the laboratory.
Colour: An attribute of things that results from the light
they reflect,transmit or emit in so far as this light causes a
visual sensation that depends on its wavelegth.
Light: Light is a form of visible energy that is part of the
radiant energy spectrum.Visible light spectrum ranges
from 400-700 nm.
Colour mixing: In the additive or light-mixture colour
mixing system;red,green,blue are the primary
colours.Mixing two primary colours produces a secondary
colour.
Red+green=yellow ; Green+blue=cyan ;
Red+blue=magenta
This system applies only to combining lights & illuminants.

3. In the subtractive or pigment-mixture system,the
secondary colours in the additive system yellow-
cyan-magenta are the primary colours.
Yellow+cyan=green ; Cyan+magenta=blue ;
Magenta+yellow=red
In dental ceramics both additive & subtractive
concepts are used.

4. Colour description:Two systems may be used
to describe colour:
1. Munsell (1915) colour order system-more
visually descriptive:the system describes
colour possessing three dimensions-
i. Hue
ii. Value
iii. Chroma
2. Cielab (1976) colour system-more
quantitative

6. Colour of human teeth:
Spectrophotometer studies shows a hue range
of 6 YR to 9.3 Y,a value range of 4-8 & a
chroma range from 0-6. Hence the human
teeth lie in the yellow-red to yellow portion
of colour wheel,with value range in the
lighter portion,which indicates that very
dark teeth are uncommon.The chroma
range is towards the lower scale,which
indicates that strong colours are not found.
Colour perception:This involves the
participation of three factors:
1. The observer
2. The object being observed
3. The light source
Observer:Perception of colour depends on
the observer’s visual individuality.It depends
on the age,duration of the exposure of the
eye,fatigue,colour blindness.

7. Object: When light falls on an object,it is
absorbed,reflected,transmitted or refracted depending
on the light transmitting ability of the object.This
produces characteristic quality of that colour.
Light source: The light source utilized has a definite
effect on the perception of colour.There are commonly
three available source-natural daylight,incandescent
light & fluorescent light.LED lights are also being used
currrently.
Example: of commercially available colour
corrected lights are-Demetron shade light &
Vita-Lite.
Metamerism:An object appears to be having
different colours when viewed under
different light source.

8. Principles of Shade
Selection
1. Teeth to be matched must be clean
2. Remove bright colors from field of view
- makeup / tinted eye glasses
- bright gloves
- neutral operatory walls
1. View patient at eye level
2. Evaluate shade under multiple light
sources
3. Make shade comparisons at beginning of
appointment
4. Shade comparisons should be made
quickly to avoid eye fatigue

9. Shade Guides
Shade matching is performed either visually
(using shade guide) or by electronic shade
taking devices or by shade distribution
chart.
Visual :
Most convenient and common method of
making shade selections
Guides consist of shade tabs
◦ Metal backing
◦ Opaque porcelain
◦ Neck, body, and incisal color
Select tab with the most natural
intraoral appearance

10. Commercial Shade Guides
in visual method
• Vita Classic
• Vitapan 3D –Master
• Extended Range Shade Guides

11. Vita Classic Shade Guide
• Very popular shade guide
• Tabs of similar hue are clustered into letter
groups
– A (red-yellow)
– B (yellow)
– C (grey)
– D (red-yellow-gray)
• Chroma is designated
with numerical values
• A3 = hue of red-yellow, chroma of 3
A B C D

12. Red/Yellow Yellow Grey
Grey
Red/Yellow

13. Vita Classic Shade Guide
Manufacturer recommended
sequence for
shade matching
1. Hue Selection
2. Chroma Selection
3. Value Selection
4. Final Check / Revision

14. Vita Classic – Step 1
(Hue Selection)
• Four categories representing hue
– A, yellow-red
– B, yellow
– C, gray
– D, red-yellow-gray
• Operator should select hue closest to
that of natural tooth
• Use area of tooth highest in chroma
for hue selection
– Difficult to select hue for teeth low in
chroma

15. Vita Classic – Step 2
(Chroma Selection)
• Hue selection has been made
(B)
• Chroma is selected from
gradations within the B tabs
– B1, B2, B3, B4
• Several comparisons should be
made
– Avoid retinal fatigue
– Rest eyes between comparisons
(blue-gray)

16. Vita Classic – Step 3
(Value Selection)
• Use of second, value ordered shade
guide is recommended
• Value oriented shade guide
– B1, A1, B2, D2, A2, C1, C2, D4, A3,
D3, B3, A3.5, B4, C3, A4, C4,
• Value best determined by squinting
with comparisons made at arms
length
– Decreases light
– Diminishes cone sensitivity, increases
rod sensitivity
– Tooth fading first has a lower value

17. Vita Classic – Step 4
(Final Check / Revision)
• Potential Problem
– Following value selection, tabs
selected for hue and chroma may
not coincide with shade tab
selected for value

18. Vita Classic – Step 4
(Final Check / Revision)
• Possible Findings / Solutions
– Value of shade tab < natural teeth
• Select new shade tab with higher
value
• Cannot increase value of restoration
with extrinsic staining
• Will only increase opacity, light
transmisison
– Value of shade tab > natural teeth
• Select new shade tab with lower
value
(or)
• Bridge difference with intrinsic or
extrinsic staining

19. VITAPAN 3D-MASTER Shade
Guide

20. Vita-3D – Step 1
• Determine the lightness
level (value)
• Hold shade guide to
patient’s mouth
• Start with darkest group moving right to left
• Select Value group
1, 2, 3, 4, or 5

21. Vita-3D – Step 2
• Select the chroma
• From your selected Value
group, remove the
middle tab (M) and
spread the samples out
like a fan
• Select one of the three
shade samples to
determine chroma

22. Vita-3D – Step 3
• Determine the hue
• Check whether the
natural tooth is more
yellowish or more
reddish than the
shade sample
selected

23. Vita-3D – Step 4
• For more precise shade, intermediate
levels for hue, value, and chroma can
be given
– 2.5M2 = value between 2M2 and 3m2
– 3M1.5 = chroma between 3M1 and 3M2
– 3M2 / 3L2.5 = hue between 3M2 and
3L2.5

24. Vita-3D – Value
Modification
• For more precise shade,
intermediate levels for value,
chroma, and hue can be given
– 2.5M2 = value between 2M2 and 3M2

25. Vita-3D – Chroma
Modification
• For more precise shade,
intermediate levels for value,
chroma and hue can be given
– 3M1.5 = chroma between 3M1 and
3M2

26. Vita-3D – Hue
Modification
• For more precise shade, intermediate
levels for value, chroma and hue can
be given
– 3M2 / 3L2.5 = hue between 3M2 and
3L2.5

27. Extended Range Shade
Guides
• Most shade guides do not cover all
the colors in the natural dentition
• Some porcelain systems extend the
typical range
• Bleached shades
• Dentin shades
• Custom shade guides

28. Electronic shade taking devices
These are electronic instruments which record
the colour of the tooth.They allow an
improved understanding of colour perception
& its correlationwith clinical aspects.
They are divided into two categories:
1.Colourimeters: It measures the absorbance of
different wavelengths of light in a
solution,e.g.Shade eye-Shofu
2.Spectrophotometers:It quantitatively
measures the reflection or transmission
properties of a material as a function of
wavelength,e.g.Easy shade-Vita.

29. Shade distribution chart
The tooth is divided into incisal,middle & cervical portions
& the colour of each region is matched independently.
Various patterns of translucency must be recognized to
attain good results.In younger patients the incisal
enamel is thick & very translucent.As translucency
increases the value decreases.Over years of
function,this enamel is lost.Similarly the thickness of
the enamel on the buccal aspect also decreases &
allows the dentine to dominate the shade.
Individual characteristic are then marked.The surface of
the tooth or the restoration determines how much of
light is reflected away.This produces changes in the
perceived colour of restoration.Younger teeth show a
great deal of surface characterization like
stippling,developmental lobes,ridges & striations.Older
teeth,due to wear show a smoother,highly polished
surface.
.

30. Lab instructions
To make a high-quality fixed prosthesis, all members
of the dental team must understand what they can
reasonably expect from each other. A mutual
knowledge of individual limitations is also
critical.The dentist who does not understand and
appreciate the challenges faced by the technician
is at a serious disadvantage when prescribing and
delegating laboratory procedures . Critical to the
development of sound clinical judgment is a
thorough understanding of technical procedures
and their rationale.
MUTUAL RESPONSIBILITIES
Good communication is the key to a dental team's technical
success. This requires a close working relationship between
the dentist and laboratory technician.Anticipating
satisfactory results is absolutely unrealistic if the dentist
does not have a reasonable amount of experience with, and
a thorough understanding of, dental laboratory procedures.

31. The American Dental Association (ADA) has issued
guidelines to improve the relationship between dentist
and technicians.
The dentist, being duly licensed, should:
(1) Provide the laboratory with signed written instructions
detailing the work which is to be performed and
prescribing the appropriate materials to be used;
(2) Provide the laboratory with accurate impressions,casts,
interocclusal records or mountings;
(3) Identify the margins, postdam, borders, relief and/or
prosthetic design on all submitted cases;
(4) Furnish a shade description, photograph,drawing or
shade button that most closely achieves the desired
results;
(5) Provide a verbal or written approval for thelaboratory to
proceed with the fabrication of the prosthesis or approve
modifications, if notified by the laboratory that a
submitted case may have questionable areas or unclear
instructions and submit written approval to the
laboratory after the item in question has been clarified;
(6) Retain a copy of the written instructions for aperiod of
time as may be required by law;
(7) Follow appropriate laboratory infection control protocol
as outlined in the ADA's infection control guidelines.

32. The dental laboratory should:
(1) Produce dental prostheses following the
written instructions provided by the dentist
and using the impressions, casts,
interocclusal records or mountings as
submitted;
(2) Review the case with the prescribing dentist
for clarification if a question arises;
(3) Match the shade as described in the original
instructions, within the limitations of the
materials available for use;
(4) Notify the dentist immediately if it is
determined that work on the case cannot
proceed;
Section 3 Laboratory Procedures
(5) Fabricate the prostheses in a timely manner;
(6) Inform the dentist of the materials used in
the fabrication of the case;
(7) Follow appropriate laboratory infection
control protocol as outlined in the ADA's
infection control

33. RESPONSIBILITIES OF THE DENTIST
The dentist has the overall responsibility for the treatment
rendered. Delegating many procedures to auxiliary
personnel is possible if all the necessary information is
provided to enable them to deliver high-quality service.
However, errors such as insufficient tooth reduction,
uncertainty about the location of tooth preparation
margins, improper interocclusal records and articulations,
and ambiguity in communicating the desired shades for
esthetic restorations to the technician hamper this
responsibility
WORK AUTHORIZATION
In addition to certain general information that is required by
law, a work authorization form (Fig. 16-8)should include
the following:
1. General description of the restoration to be made
2. Material specification (e.g., ADA Type IV gold)
3. Desired occlusal scheme
4. Connector design for FPDs
5. Pontic design, including the material specification for tissue
contact
6. Substructure design for metal-ceramic restorations
7. Information regarding the shade selection for esthetic
restorations
8. Proposed RPD design (if applicable)
9. Date of the next scheduled patient appointment

34. Shade Selection:
With the prevalence of metalceramic restorations,
dentists and technicians have become acutely aware of the
difficulty involved in communicating shade selection. A
thorough understanding of the principles of color science
and the use of internal and surface colorants is essential to
both parties. Many dentists and technicians have found a
diagram of the tooth that allows specifications of multiple
shades helpful (Fig. 16-10). 11 The diagram should be large
enough to designate a cervical shade, an incisal shade, and
any applicable individual characterization. Diagrams on most
preprinted laboratory prescription forms do not provide
adequate space (see Fig. 16-8), so other space must be
available. A separate entry regarding the value or brightness
can be helpful. When selecting a shade, the dentist should
use a guide that corresponds to the ceramic system used by
the technician. On occasion, it may not be possible to obtain
a match with a simple shade guide (e.g., the Vita Lumin
vacuum system). In those cases an alternative guide or a
shade distribution chart (outlined in Chapter 23) should be
used. The dentist must have excellent color perception skills
and should be able to precisely transfer those onto a written
prescription that includes a large, detailed diagram that
allows the ceramist to accurately reproduce the shade
observed and described by the clinician. Close
communication and cooperation are obviously necessary,
and a trial porcelain firing may be needed.

35. A practical alternative to written color
communication
is the use of light-cured, resin-based staining
kits to custom-stain a shade-tab. The closest matching
shade-tab is selected and modified using stains
mixed with liquid resin. Once the desired match has
been obtained, the resin is light-cured, and the cus-
tomized tab is sent to the dental laboratory. The ceramist
then has an actual reference and can compare
the work and make the required modifications, thus
ensuring predictable success.
If esthetic requirements are extensive or difficult
to communicate through the means described above,
involving dental laboratory personnel in the shade
selection process may be helpful. The ADA takes the
position that when a dentist requests the assistance
of a dental laboratory technician in the shade selection
process, this does not constitute the practice of
dentistry by the technician, provided the activity is
undertaken in consultation with the dentist and that
it complies with the dentist's written instructions.
Such assistance is most appropriately provided

36. Fig. 16-10. A shade distribution chart must be adequate
in size to permit inclusion of enough detail. Subtle differences
observed in cervical shades are identified, as are surface
details such as hypocalcification, incisal translucency,
and stains.

37. Sample Laboratory Prescription form

38. Reference
1.Contemporary Fixed
Prosthodontics-
Rosensteil,Land,Fujimoto
2.Fundamental of FPD – Shillingburg
3.Textbook of Prosthodontics-V
Rangarajan,TV Padmanabhan
4.www.google.com

39. Thank YOU