Shade selection/ academy laser dentistry


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Shade selection/ academy laser dentistry

  1. 1. INDIAN DENTAL ACADEMY Leader in continuing dental education
  2. 2. THE MEANING OF SHADE SELECTION COLOUR Energy wave of specific wave length Shade Matching Matching two objects that reflect similar wave lengths of electromagnetic spectrum
  3. 3. Wave lengths of electromagnetic spectrum perceived by human eye -Visible light • Ultraviolet rays • x-rays • gamma rays • Infrared • Microwaves • Television & Radio waves 380 760
  4. 4.
  5. 5. An understanding of the nature of light & how the eye perceives & the brain interprets light as colour is important for successful shade selection
  6. 6. Perception of colour 3 types of cones- sensitive to : Blue (short) green (Medium) Red(long) Ultimate colour depends on the relative amount of stimulation of the three receptors
  7. 7. Seeing colours is possible , since all objects absorb certain parts of the light, while reflecting or transmitting other parts A surface appears to be of a particular colour when it reflects that wave length and absorbs all others With out light there is no
  8. 8. •A surface appears white when it reflects the entire spectrum of wavelengths. •A surface appears black when it absorbs all light rays •A surface appears grey when all the wave lengths of light are reflected and absorbed in equal measure
  9. 9. Additive and Subtractive Colours Additive Colours =light mixture system Primary colours •Red •Green • Blue Secondary Colour •Yellow •Cyan •magenta
  10. 10. Additive and Subtractive Colours Subtractive Colours
  11. 11. Dimensions of colour Hue The name of the color – Could be red, green, yellow • This would depend on the wave length of the reflected light. • Short wave length = Violet Hue • Long wave length = Red Hue • Studies show that most natural teeth fall in a Hue range between yellow and yellow-red – 6YR-9.3YR
  12. 12. Dimensions of colour Value Amount of Gray in the Hue • Most important factor in tooth shade matching. – Tooth with high value looks vital (alive) – Tooth with low value looks gray (lifeless) • Is a direct consequence of the amount of light energy an object reflects or transmits. • Studies have shown most teeth fall in a range from 4-8
  13. 13. Dimensions of colour Chroma Saturation of the Hue • High Chroma = High amount of Hue with little dilution • Low Chroma = Small amount of Hue with large amount of dilution – Studies have shown that teeth have a Chroma range of 0-7 – An achromatic shade would then have a Chroma number near 0
  14. 14. Dimensions of colour Maverick: •Defined as any color or colors located in dentin but not directly responsible for hue. •They are called maverick colors because they are strewn throughout the dentin without organization. •Found in dentin of most teeth. •Formed from chemical reactions between organic and inorganic materials contained in dentin. External tooth environment, including saliva and occlusion, together with diet, blood and nerve supply to tooth are sufficient to cause interactions. •They combine with hue, chroma and are projected through enamel to be perceived as composite tooth colour.
  15. 15. Munsells colour system Value : along long axis Hue : along rim of the wheel Chroma: increases from center to periphery
  16. 16. Munsells colour system -Hue •Ten basic hues; 5 principal hues & 5 intermediate •Each hue segment-10 major segments- further 100 fractions •Total of 10,000hues
  17. 17. Munsells colour system -Value •Ten basic values: pure black at bottom pure white at the top •Each further divided into 100 segments •Total of 1000 values
  18. 18. Munsells colour system -Chroma •Purest colour arranged towards periphery •Degree of possible saturation of a hue is variable for each level of value -irregular shape of munsell solid
  19. 19. Munsells Notation •The designation of any particular color located in the Munsell color solid is given by the notation HV/C H-hue V-value C-chroma •Color of natural tooth is in the range of 6YR4/10 - 9.3Y8/7
  20. 20. CIE L*A*B •In this system all the colors are arranged in one plane on which the lightness values can be changed vertically •L* (vertical axis) defines brightness or darkness of color = value in Munsell system • a*b* represent chromacity
  21. 21. CIE L*A*B •The color difference between two colors can be calculated as ∆E= ∆ L 2 * + ∆ a 2 * + ∆ b 2 * •The of advantage this system over the Munsell system is equally arranged gradations in color space •Any colour is represented by a unique point in space denoted by numerical representation of the coordinates L*a*b color chart
  22. 22. Colour temperature
  23. 23. Colour temperature
  24. 24. Translucency & opacity Transparent translucent opaque
  25. 25. With increasing opacity of teeth the grey scale value decreases and the brightness value increases.The Higher the brightness values,the lower the transparency becomes.The more transparent a tooth the more grey it appears
  26. 26. B &C -Translucent areas of the teeth appear grey A B C A-opaque incisal edge appears white
  27. 27. The opal effect Fine particles in enamel (hydroxyapatite crystals) responsible for opal effect Fine particles reflect short wave lengths and allow longer wave lengths to pass through -hence tooth shows •Bluish areas in reflected light •Orange red areas in transmitted areas In reflected light In transmitted light
  28. 28. Photoluminenescence : fluorescence & phosphorescence Phosphorescence : continue to emit visible light after being struck by U-V light Fluorescence: emit visible light only as U-V rays strike them •Human enamel is fluorescent •Takes place even under day light conditions but usually goes unnoticed •Becomes pronounced under high energy U-V light environment eg. Discos •Lack or abundance of fluorescing agents in restorations may produce undesirable effects
  29. 29. Tooth colors are situated in the upper lightness area of the color space, well defined as yellow-red color tones. The shape of this tooth color space resembles a banana in an upright position. This signifies that all tooth shades - regardless of perception - can be clearly defined. Knowing the position of the color space of natural teeth provides the basis for reliable and accurate shade determination and allows for aesthetically perfect tooth reproduction. The tooth color space
  30. 30. studies of tooth shades have shown: the distribution of natural tooth shades - just like all "populations" in nature - comes close to a normal distribution. That is, certain tooth shades - defined by the parameters of value, chroma and hue - occur more frequently whereas other - more extreme - kinds of shades are found quite rarely.
  31. 31. Factors that influences the shade perception
  32. 32. Cone color perception decreases the longer an object is looked at. – The Hue range gets less and less (Gets grayer) – This suggests that one should not stare at a tooth but look briefly and then look away When looking away, you should look at a neutral or gray background to allow cone sensitivity to return Factors Affecting Color Perception Color Adaptation:
  33. 33. Factors Affecting Color Perception Complementary Colors affect each other: • When placed side-by-side they may appear to increase Chroma • Hue and Chroma selection may be affected by the color of lipstick or make-up the patient is wearing. Deceptive Color Perception:
  34. 34. Factors Affecting Color Perception Affects about 8% of the male population – Very few cannot see color at all, most have an inability to detect the differences in Chroma - This is called monochromatism – Requires then an alternate method of shade selection. Color Blindness: • Use of office staff • Special training to overcome or adapt Colour vision test plate You should be able to see the no.
  35. 35. Factors that influences the color of an object? • The physical properties of the object • The nature of the incident light in which the object is viewed • The relationship or close association to other colored objects • The color background of the viewer
  36. 36. The nature of the incident light in which the object is viewed Colours of two objects appear to match under one set of viewing conditions but differ under different light conditions - metamerism
  37. 37. The nature of the incident light in which the object is viewed Clinical significance :tooth & restorative material of a differing shade may appear matched under certain light conditions , but may show discrepancy in day light tooth restorative Appear Matched mismatch
  38. 38. Ideally light source for shade matching: •Should have complete colour content •Enough intensity •Comfortable to the eye •Standard- unchanging in quality & quantity Northern exposure sunlight at mid day with slightly overcast sky considered ideal- equal blend of all wave lengths of light Unfortunately all clinics may not have access to natural sunlight and even if available,may not have adequate intensity .
  39. 39. Most common lighting is either: – Incandescent – Fluorescent • Neither is pure white light – Incandescent is higher in yellow than blue – Fluorescent is higher in blue waves Light in the Dental Office Chair light is not recommended for colour matching as it is over powering and interferes with fine discrimination of three dimensions of colour
  40. 40. The concept of Colour Rendering Index (CRI): •Capacity of artificial light to reproduce natural light •White light has CRI of 100- is constituted of equal energies from all the three primaries of the spectrum ie. Red , blue, green. •Artificial sources with CRI 90 are adequate Warm white fluorescent –CRI 56 Cool white fluorescent –CRI 68 Colour corrected fluorescent CRI –above 90
  41. 41. Amount & location of lighting Ideal amount of light –1500 lux -This over comes influence of ambient room light -not so intense that slight colour differences are overcome or washed out Location of light •All luminous ceiling Surrounding environment Bright coloured environment Interfere with proper colour match Light grey –ideal background
  42. 42. Selection should be made when subject tooth and adjacent teeth are clean. Principles of Shade Selection Selection should be made at the start of the appointment before operator’s eyes get tired Cosmetics should be removed and bright colored clothes covered
  43. 43. The shade tab should be Held as close to the subject tooth as possible.This lets the incident light hit both at the same angle
  44. 44. A blinder of neutral grey may be used to separate the tooth from its surrounding - hence no near by colour can interfere in judgment
  45. 45. • Use multiple light sources or have an operatory of color corrected lights • View the subject tooth quickly – Do not stare at the tooth-eye accommodates and becomes biased – Move your eyes away and look at a neutral color (light blue or grey)to readapt vision to orange – yellow portion of spectrum
  46. 46. Shade selection for resin composites •Standard shade guides e.g.. Vita & use corresponding shade of composite material •Shade guides supplied by the respective manufacturers •Custom shade tabs
  47. 47. (Esthtet x )
  48. 48. Translucent bodies demonstrate the property of changing their colour with increased thickness.Colours become darker and more intense
  49. 49.
  50. 50. Conversion chart Composite materials usually carry Shade information in one system (e.g..A3, i.e..vita) However if the clinician does not have the same shade guide a conversion chart may be used
  51. 51. Types of Shade Guides Hue – Chroma shade guide Allow an approximate Colour shade to be given Eg. Vita Lumin vaccum – 15 shade tabs Mass shade guide Allow an more accurate shade matching Eg. Vita 3D master- 26 shade tabs
  52. 52. Vita lumin Four basic hues of Vita Shade guide A Brownish tones B Yellowish tones C Greyish tones D Reddish tones A1, A2, A3,A3.5,A4 represent increasing chroma
  53. 53. Vita lumin The following arrangement of shade tabs indicates decreasing value B1*A1*B2*D2*C1*C2*D4*A3*D3*A3.5*B4*C3*A4* C4* Brightest Darkest • Begin by selecting hue.Maximum chromas of hue are selected- A4,B4,C4,D4 and compared against the teeth. •After basic hue has been determined chroma is chosen Sequence of Shade Selection
  54. 54. The tooth colors of conventional shade systems do not feature systematic colorimetric distribution in the tooth color space. Shade guides – Vitapan 3D Master VITAPAN 3D-MASTER provides a systematic uniform and complete colormetric coverage of the tooth color space.
  55. 55. Shade guides – Vitapan 3D Master Tolerance cloud Rationale: The most frequent tooth Colours are located in the middle Human eye can tolerate greater variation in value than in chroma or hue
  56. 56. In the first step of the shade taking procedure the value (lightness) is determined. Select the value level from the five value groups (levels 1 - 5) that is closest to the value of the tooth to be compared. Vitapan 3D Master
  57. 57. Pull out the medium shade sample (M) from the selected value group. Then the chroma (levels 1 2,3) is determined. Select the color sample of the selected M group that is closest to the tooth to be compared. Vitapan 3D Master
  58. 58. In the third step the hue (L, M, R) is determined. Check whether the natural tooth displays a "more yellowish" (L) or "more reddish" {R) shade than the color sample of the M- group that has been selected in the second step. Now the best matching shade sample is determined and the information is recorded in the color communication form. Vitapan 3D Master
  59. 59. 2 L 1.5 Value Hue Chroma Color communication form
  60. 60. Chromascop Based on the concept that tooth shade blends in with overall appearance of individuals.
  61. 61. Chromascop According to this concept individuals can be classified into two types •Amber reflectors Spring type , autumn type •Grey reflectors Summer type ,Winter type Tooth shade is in harmony with the colour of the skin,hair, eyes &
  62. 62. Spring types •200 shade group •Golden to medium blond hair •Light grey eyes •Pink pale skin
  63. 63. Autumn types •(300 shade group) •Medium blonde- red hair •Dark blue eyes to green – blue eyes •Pale reddish skin
  64. 64. Summer types •100 shade group •Ash grey to medium brown hair •Slightly pink to pale skin •Grey-blue eyes
  65. 65. Winter types •400 & 500 shade group •Dark brown to black hair •Icy blue/green eyes •Amber skin Dark skinned individuals -Asians allocated to this type
  66. 66. The Noritake Shade Guide The Noritake Shade Guide has. a) Intermediate shades (NP1.5 , NP2.5) These two shades are often seen in natural teeth: NP1.5: The chroma is between A1 and A2 shedes - the hue corresponds to the slightly reddish shades. NP2.5: The chroma is between A2 and A3 shades - the hue corresponds to the slightly reddish shades.
  67. 67. Shade matching in Glass ionomer Vita shade Biochromatic shade
  68. 68. Shade selection Acrylics •Custom shade tabs •Standard shade guides •Custom shade tabs
  69. 69. Shade distribution chart •Tooth divided into 3 regions •Each region matched independently •Individual characterstics marked
  70. 70. Colour measuring devices They remove the subjectivity out of the colour matching process Shade vision system Vita easy shade •Still in their infancy lack the ability to match the shade of the tiny, fine details
  71. 71. An understanding of the science of colour and colour perception is important if success is to be attained in the ever expanding field of esthetic restorative dentistry. Although limitations in materials and techniques may make a perfect colour match impossible, a harmonious restoration can almost always be achieved . Shade selection should be done in a methodical and and organised manner. This will enable the practitioner to make the best choice and communicate it accurately to the laboratory Conclusion
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