Understanding colour

1. Colour is a human need like fire and water. It is a raw material indispensable to life - Fernand Leger (artist) The science and art of porcelain laminate veneers - Galip Gurel 1

2. Understanding Colour Presented by: Apurva Thampi MDS 1st year The science and art of porcelain laminate veneers - Galip Gurel 2

3. Contents • Introduction • Types of colour • Colour perception • Factors influencing colour perception • Dimensions of colour • Colour measurement • Contrast effect • Impact of materials and material science on colour • Shade selection • Systems for shade selection • Steps in shade selection • Advances in shade selection The science and art of porcelain laminate veneers - Galip Gurel 3

4. Introduction • Clinician masters the art and science of colour treatment planning • Clinician has correctly communicated the shade selections to the laboratory • Correct interpretation by the laboratory technician For a successful esthetically pleasing anterior restoration The science and art of porcelain laminate veneers - Galip Gurel 4

5. Terminologies • Translucency : It is the amount of incident light transmitted and scattered by the object • Opacity: It is the opposite of translucency. It is the ability of a material to block the passage of light MATERIAL WITH HIGH OPACITY IS THE MATERIAL WITH LOW TRANSLUCENCY The science and art of porcelain laminate veneers - Galip Gurel 5

6. • Opalescence : Optical property of the material in which there is a scattering of the shorter wavelength of the visible spectrum. • Iridescence : it is the rainbow like effect of different colours which changes according to the angle from which they are viewed or the incidence angle of the light source The science and art of porcelain laminate veneers - Galip Gurel 6

7. • Fluorescence : Absorption of light by a material and the spontaneous emission of light in a longer wavelength. • Luminiscence : Any process in which energy is emitted from a material at a different wavelength from that at which it is absorbed The science and art of porcelain laminate veneers - Galip Gurel 7

8. • Phosphorescence: Light emitted by an atom or molecule persists after the excitation source is removed. It is temperature dependent The science and art of porcelain laminate veneers - Galip Gurel 8

9. Types of colour Spectral colours The science and art of porcelain laminate veneers - Galip Gurel 9

10. Types of colour Pigment colours Primary colour Secondary colour Complementary colour The science and art of porcelain laminate veneers - Galip Gurel 10

11. Colour perception • Absorption and reflection of various wavelengths of light • Psychophysical reality of colour The science and art of porcelain laminate veneers - Galip Gurel Colour Perception Psychophysiological reality Physical Wavelength of light Psychophysical Reception of wavelength of light by the eye Psychological Interpretation of wavelength of light by the brain 11

12. Factors influencing colour perception Illuminant ObserverObject • Colour content • Colour rendering effect • Reflection • Transmission • Individual differences • Binocular differences • Age • Drugs • Fatigue The science and art of porcelain laminate veneers - Galip Gurel 12

13. Color content: Intensity of light emitted at each wavelength which varies according to the type of illuminnat Colour rendering: It is the effect that the illuminnt has on the colour appearance under a reference source Colour rendering index: Measue of the degree to which the illluminnat can impart colour of an object compared with that acheieved by a reference source The science and art of porcelain laminate veneers - Galip Gurel 13

14. Reflection: A material gains it reflective colour by reflecting the part of the spectrum of light incident upon it and absorbing the other parts of the spectrum Transmission: A translucent material gains its transmitted colour by the spectrum it transmits. Wavelengths that are not transmitted are absorbed The science and art of porcelain laminate veneers - Galip Gurel 14

15. • Individual differences in colour Number of Dentist Number of prosthesis Number of natural teeth total Same shade selected by 3 dentists 18 teeth (14%) 10 teeth (14.3%) 28 teeth (14%) Same shade selected by two dentists 72 teeth (59.2%) 30 teeth (42.9%) 102 teeth (51.5%) Same shade selected by 0 dentists 38 teeth (26.7%) 30 teeth (42.9%) 68 teeth (34.3%) The science and art of porcelain laminate veneers - Galip Gurel 15

16. • Chronological age and colour perception The science and art of porcelain laminate veneers - Galip Gurel 16

17. • Fatigue and colour perception • Adverse visual perception – due to systemic/local/mental fatigue • Drugs and colour perception Drug Effect Alcohol/Morphine Long wavelength = brighter Short wavelength = darker Caffeine Long wavelength = darker Short wavelength - brighter The science and art of porcelain laminate veneers - Galip Gurel 17

18. It is the phenomenon where an object appears different in different lighting Tooth under corrected lighting Tooth under fluorescent lighting Tooth under incandescent lighting M E T A M E R I S M The science and art of porcelain laminate veneers - Galip Gurel 18

19. Dimensions of colour Hue Value Chroma Translucency The science and art of porcelain laminate veneers - Galip Gurel 19

20. Munsells colour system CIE colour system The science and art of porcelain laminate veneers - Galip Gurel 20

21. Attribute of colour that makes it appear blue, yellow or red Lightness or darkness of colour Intensity of colour or amount of hue saturation (runs from 0- 10) HUE CHROMAVALUE The science and art of porcelain laminate veneers - Galip Gurel 21

22. • Developed by Commision International de l’Eclairage • Based on the concept of TRICHROMACY • Three primaries – tristimulus values • 1931 – concept of standard observer was introduced The science and art of porcelain laminate veneers - Galip Gurel 22

23. • Terminologies used in CIE colour system • Imaginary primary colours – [X], [Y], [Z]Primaries • In 1964 – a 2º viewing angle • Characterise response of cone receptors denoted as x,y and z • Perception of colour depends on, light, object, observerTristimulus values • Decribes the other two dimensions of colour Standard observer Chromaticity Color matching function Chromaticity diagram The science and art of porcelain laminate veneers - Galip Gurel 23

24. In CIE L*a*b • L represents lightness or value • ‘a’ is the measurement along red-green axis • ‘b’ is the measurement along yellow -blue axis Colour difference ΔE* = [(ΔL*)2 + (Δa*)2 + (Δb*)2]1/2 The science and art of porcelain laminate veneers - Galip Gurel 24

25. Colour measurements Spectrophotometers It measures the amount of light reflected at each wavelength Double beam spectrophotometer Compares responses with a reference standard Colorimeters It measure the amount of light reflected at selected colours are based on the CIE tristimulus Disadvantages: EDGE EFFECT The science and art of porcelain laminate veneers - Galip Gurel 25

26. • Photography + spectrophotometry Clinician holds 3-4 most matching shade guides Photographed under 35mm camera under balanced light Sent to dental laboratory A computer program aids in selecting the closest match The science and art of porcelain laminate veneers - Galip Gurel 26

27. Contrast effects Optical illusions Simultaneous contrast Light/Dark contrast Hue contrast Successive contrast The science and art of porcelain laminate veneers - Galip Gurel 27

28. The science and art of porcelain laminate veneers - Galip Gurel 28

29. Light/ Dark contrast Hue contrast The science and art of porcelain laminate veneers - Galip Gurel 29

32. Areal contrast Visual colour perception affected by the size of the object The science and art of porcelain laminate veneers - Galip Gurel 32

33. Spatial contrast Spatial contrast is equated to brightness and size The science and art of porcelain laminate veneers - Galip Gurel 33

34. • One colour is observed after the perception of another colour The science and art of porcelain laminate veneers - Galip Gurel 34

35. Impact of materials and material science on colour • McLean from England – innovators in dental ceramics • Improved characteristics – higher density • Increased density – better light transmission • Five categories of materials used in tooth coloured restorations • Sintered Aluminium oxide ceramics (Procera) • Lithium disilicate ceramics (IPS Empress 2 Eris) • Leucite reinforced ceramics (Empress I, Cerpress SL) • Feldspathic ceramics (Creation, Ceramco 3, Finesse) • Synthetic low fusing quartz glass ceramics (HeraCeram) The science and art of porcelain laminate veneers - Galip Gurel 35

36. • Full coverage – excellent marginal adaptation • High resistance to fracture (690 Mpa) • High opacity • Low translucency The science and art of porcelain laminate veneers - Galip Gurel 36

37. • Developed in 1998 (IPS Empress 2) • Fracture toughness – 340 Mpa • Excellent marginal adaptation and superior marginal integrity • More opaque than conventional materials • Esthetically beneficial for masking discoloured teeth The science and art of porcelain laminate veneers - Galip Gurel 37

38. • Developed by Ivoclar in 1990 • Fracture toughness – 180MPa • Can be fabricated with varying forms of opacity – high, medium and translucent The science and art of porcelain laminate veneers - Galip Gurel 38

39. • Weinstein in 1960 – metal ceramic restorations • Highly versatile • Can be produced using platinum foil or refractory die technique The science and art of porcelain laminate veneers - Galip Gurel 39

40. • Karino in 1982 – metal ceramic restoration • McLaren in 1998 – fired at 100ºC lower than feldspathic ceramic • Chu in 2001 – completely synthetic glass ceramic for metal ceramic restorations • Causes less wear to the opposing natural tooth • Low opacity • High translucency The science and art of porcelain laminate veneers - Galip Gurel 40

41. To be continued… The science and art of porcelain laminate veneers - Galip Gurel 41

42. Welcome back!!! 42

43. Shade matching Shade matching is a process of converting shade perception into shade communication The science and art of porcelain laminate veneers - Galip Gurel 43

44. Importance of shade matching in dentistry Natural appearance of the teeth Proper communication with the dental laboratory The science and art of porcelain laminate veneers - Galip Gurel 44

45. Shade guide systems Conventional shade guide systems Technology based shade guide systems The science and art of porcelain laminate veneers - Galip Gurel 45

46. Conventional shade guide systems • Used as visual guides • Require a neutral environment • Maintenance of quantity and quality of light • Absence of eye fatigue • Examples : Vitapan Classical, Ivoclar Chromascope, Vitapan ED Shademaster The science and art of porcelain laminate veneers - Galip Gurel 46

47. Vitapan Classical shade guide • Based on hue • Categorised into groups • A – Orange • B – Yellow • C – yellow/gray • D – Orange/gray (brown) Chromascope system • Based on hue • Uses numbers instead of letters • 100 – white • 200 – yellow • 300 – orange • 400 – gray • 500 - brown Vitapan 3D shademaster • Based on value • Different from conventional systems • L – tendency towards yellow hue • R – tendency towards red hue • Developed by Miller and further by McLaren The science and art of porcelain laminate veneers - Galip Gurel 47

48. Sequence for shade selection Basic shade Basic shade variations Enamel shade, translucency and location Special effects The science and art of porcelain laminate veneers - Galip Gurel 48

49. Armamentarium for shade selection Shade guide Shade prescription form Accesory shade guides Instant photograph or slide Daylight colour corrected fluorescent lighting Neutral environment The science and art of porcelain laminate veneers - Galip Gurel 49

50. • Accessory armamentarium include: • Magnifying loops • Fluid resin stains • Custom shade tabs • Hand mirror The science and art of porcelain laminate veneers - Galip Gurel 50

51. Basic shade • Match centre shade of natural tooth with closest appropriate tab • Hue should be assessed correctly • Tabs with same colour may appear similar • Doubts?? - compare two approximate matching tabs under the natural tooth The science and art of porcelain laminate veneers - Galip Gurel 51

52. • A shade – young individuals • B shade – rarely encountered in natural dentition • C shade– middle aged / older individuals - subgroup of B ( similar hue but lower value) • D shade– subgroup of A The science and art of porcelain laminate veneers - Galip Gurel 52

53. Basic shade variations ORANGE MODIFICATION • Natural tooth colour - either orange or yellow hue • Porcelain shade guides are yellow hue not orange • Orange tonality – confined to cervical aspect of the tooth • Apply fluid colour resin – helps visualize quality or intensity of tone The science and art of porcelain laminate veneers - Galip Gurel 53

54. VARIATIONS BASED ON LOCATION • Most frequent variation observed at the incisal third • Next frequent was uniform – monochromatic appearance • Thirdly, colour deviation from basic hue – cervical third • Cervical variations – cervical part of the shade tabs • Basic hue of the incisal third – mammelon colour • Mammelon – blunt and widen with aging – whitish orange hue The science and art of porcelain laminate veneers - Galip Gurel 54

55. Laboratory considerations • Basic hue – dentin build-up • Single shade or different hues alternated horizontally • Opal/vintage porcelain system – bright shades of high value – preserve value through firing cycles • Mix 10% corresponding value plus porcelain with dentin shade The science and art of porcelain laminate veneers - Galip Gurel 55

56. • Additional brightness – mix 20 – 30% of value plus porcelain • Shades with low value – value plus porcelain - separate opaque layer • Modified dentin shades – cervical dentin, mammelon dentin, orange modified dentine, secondary brown/orange dentine The science and art of porcelain laminate veneers - Galip Gurel 56

57. Enamel shade and translucency • Quality and location of enamel overlay • Young individual – whiter teeth, middle aged – orange teeth (translucent or almost transparent enamel) • Evaluation done in 2 ways • Patient holds the tab below the tooth while the clinicians stands back 2 yards • Patients holds the tab below the tooth and stands facing a mirror whielt the clinicians makes the evaluation from behind • Natural tooth has higher value – low chroma/high value dentine + opaque reflective dentine is used The science and art of porcelain laminate veneers - Galip Gurel 57

58. Laboratory considerations • Young tooth – bright reflective enamel • Increased translucency – enamel mixed translucent or transparent powder • Maintain same degree of opacity – overlaid over enamel The science and art of porcelain laminate veneers - Galip Gurel 58

59. Need for improved systems for shade selection Selection subject to variability Shade selection protocol has several difficulties Metamerism Improved ceramics – changes in light reflection, absorption, refraction and dispersion The science and art of porcelain laminate veneers - Galip Gurel 59

60. Technology based shade guide systems 1998 – Shofu SadeEye – Ex Chroma Meter 1999 – Vita Easy shade 2000 – Shade scan 2000 – ShadeRite Dental Vision system 2001 – SpectroShade System The science and art of porcelain laminate veneers - Galip Gurel 60

61. Shofu ShadeEye – Ex Chroma meter • First reported by Goldstien • Freestanding hand held probe – 3mm • Placed against tooth – activated • Flash of light through probe • Reflected light transmitted through centre of probe • Evenly distributed through colour filters • Docking unit via infrared signal • Database of porcelain samples The science and art of porcelain laminate veneers - Galip Gurel 61

62. VitaEasy Shade system • Hand held spectrophotometer • Connected to based by mono-coil fibre optic cable assembly • Contact probe tip – 5mm • 19 - 1mm diameter fibre optic bundles • Tooth illuminated by a halogen bulb • Spectrometers measure the internally scattered light • Spectral reflectance is measured in 25 nm bandwidth • Displays closest vita shade in classical/3D guide system The science and art of porcelain laminate veneers - Galip Gurel 62

63. ShadeScan system • Hand held probe + LCD screen • Fibre optic cable – halogen light – incident on tooth surface at 45 degrees • Light intensity continuously monitored • Image recorded on a flash card The science and art of porcelain laminate veneers - Galip Gurel 63

64. ShadeRite Dental Vision system • Hand held + LCD screen • Glare spot for focus and alignment • Focused on junction of gingival and middle thirds • Measurement through series of rotating filters • Shade and translucency mapping possible and downloaded The science and art of porcelain laminate veneers - Galip Gurel 64

66. SpectroShade system • Most complex • Most flexibility – data • Digital color imaging with spectrophotometric analysis • Large hand piece • 2 step process • Postioned against green and white background • Light halogen tube on tooth – 45 degrees • Image is seen on computer screen • Incident light monochromated • Spectral scanning – 10nm bandwidth The science and art of porcelain laminate veneers - Galip Gurel 66

68. Clear match system • Purely software based • Requires a Windows PC and digital camera • Black white standards and shade tabs need to be included in each photo • Detailed shade mapping is possible The science and art of porcelain laminate veneers - Galip Gurel 68

69. Conventional V/S technology based systems - Advantages Conventional • Cost effective • Easy to use • Visual tool • transportable Technology based • More objective • Verification of restoration shade in the lab • Not influenced by surrounding environment • Increased producvtivity • Tooth dehydration not an issue The science and art of porcelain laminate veneers - Galip Gurel 69

70. Conventional V/S technology based systems - Disadvantages Conventional • Subjective • Inconsistency in manufacturing • Easily affected by surrounding environment Technology - based • Increased cost • Interpretation of the report is technician dependent • Not easy transportable The science and art of porcelain laminate veneers - Galip Gurel 70

71. Conclusion Understanding colour requires learning the language of colour. In order to overcome the challenges associated with shade selection in esthetic dentistry, it is essential to learn the art and science of colour. Close co- operation of the clinician and the laboratory technician is also required. Only then can an ultimately esthetic restoration be achieved “A beautiful smile is no longer considered a luxury but rather as an essential component or current lifestyle” - Stephen J Chu The science and art of porcelain laminate veneers - Galip Gurel 71

72. Bibliography • Science and art of porcelain laminate veneers – Galip Gurel • Esthetics of anterior fixed prodthodontics – Gerard J. Chiche, Alain Pinault • Advances in color matching,Jane D. Brewer, DDS, MSa,*, Alvin Wee, BDS, MSb,c,Robert Seghi, DDS, MSb : Dent Clin N Am 48 (2004) 341– 358 • Clinical Steps to Predictable Color Management in Aesthetic Restorative Dentistry Stephen J. Chu, DMD, MSD, CDT : Dent Clin N Am 51 (2007) 473–485 The science and art of porcelain laminate veneers - Galip Gurel 72

73. • Colour in relation to dentistry. Fundamentals of colour science S M Burkinshaw : British Dental Journal 196, 33 - 41 (2004) • Color matching in dentistry. Part I The three-dimensional nature of color : Robert C. Sproull, D.D.S. : JPD vol 29(4) 416 • Color matching in dentistry. Part II : Practical applications of the organization of color : Robert C. Sproull, D.D.S. : JPD vol 29(5) 556 • Color matching in dentistry. Part III : colour control : Robert C. Sproull, D.D.S. : JPD vol 31(2) 146 The science and art of porcelain laminate veneers - Galip Gurel 73

74. THANK YOU AND HAVE A PLEASANT DAY!!! The science and art of porcelain laminate veneers - Galip Gurel 74

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