seminar -color and shadematching in dentistry.pptx

color and shadematching in dentistry

1. DR JISHNU K NAIR FIRST YEAR POSTGRADUATE STUDENT DEPARTMENT OF CONSERVATIVE DENTISTRY AND ENDODONTICS

2. C0NTENTS INTRODUCTION PHYSICS OF COLOR OPTICAL CHARACTERISTICS OF COLOR COLOR IN DENTISTRY DIMENSIONS OF COLOR MEASUREMENT OF COLOR ELEMENTS AFFECTING COLOR CONVENTIONAL VISUAL SHADE MATCHING TECHNOLOGY BASED SHADE MATCHING CONCLUSION REFERENCES

3. INTRODUCTION Colour plays a critical role in the success or failure of esthetic dental restorations. Shade matching is as much an art as it is a science, and requires knowledge of colour science principles and the implementation of adequate shade-matching techniques.

4. A phenomenon of light or visual perception that enables one to differentiate otherwise identical objects . (GPT 9) Color is the property of a surface or substance due to the absorption of certain light rays and reflection of others within the range of wavelengths (380 nm to 760 nm) adequate to excite the retinal receptors . ( Textbook of OperativeDentistry – Vimal sikri ) Definition of color: Color Wheel

5. PHYSICS OF COLOR A beam of white light could be separated into component colors, or wavelengths, by passing it through a prism The resulting continuous series of colors is called spectrum These colors in the following order: red, orange, yellow, green, blue, indigo, and violet The human eye can perceive only these wavelengths of light, hence the term visible light spectrum .

6. It is the interaction of the light with the object that allows perception of color. The basic process of color perception can be described as follows. Light is emitted from a light source When light strikes the object (tooth) a proportion of the energy is absorbed, transmitted or reflected. Color Perception

7. The quantity of reflected light reaching the observer’s eyes stimulates a subjective sensation in the brain that we experience as colour The perception of colour ultimately resides in the brain and not merely in the property of the object. Colour can be defined as a psychophysical sensation provoked in the eye by the visible light and interpreted by the brain .

8. Color Vision The human eye and brain, which enable colour vision,form an amazing and complex system. At the innermost retinal layer of the eye are two types of specialized neurons that function as photoreceptors, called rods and cones .

9. For low luminances ( scotopic vision), only rods are used, which have maximum sensitivity at 507 nm. For medium and high luminances ( mesopic and photopic vision), the human eye uses the three types of cones (S-, M-, L-cones), each with different spectral sensitivity curves and peaks at 420 nm, 530 nm, and 560 nm, respectively The three types of cone cells allow us to have trichromatic vision

10. Optical Characteristics of color/teeth Knowledge of optical characteristics of teeth helps the clinician to match artificial restorations to a highly characterized natural dentition which is otherwise a challenging procedure for the clinician. The clinician can share the appropriate information from the operatory to a distant laboratory in a better way by learning the language of color and the optical characteristics specific to teeth. inside dentistry | November 2012 Clinical importance

11. Reflection AACD. Winter 2011,vol4,no.4 Clinical importance When incident light strikes the labial surface of an anterior tooth the majority is reflected back to the observer. The labial surface texture of anterior teeth is highly reflective and results in an attractive bright appearance. Primary surface texture- Line angles, Facial planes. Secondary surface texture- Developmental lobes, developmental grooves, Mamelons. Tertiary surface texture- Perikymata, Imbrication lines.

12. Transmission Clinical importance The incisal edges of teeth looks like a glass-like clarity due to presence of thin enamel . High translucency in this area is one of the reasons why human teeth do not have a stark appearance; the edges are softened by light transmission . Failure to capture this effect in ceramics is a common fault resulting in a solidity and starkness that is totally unnatural. Transclucent AACD. Winter 2011,vol4,no.4

13. Clinical importance Scattering When illuminated, incisal edges of enamel will transilluminate the reds and scatter the blues within its body; thus, enamel appears bluish even though it is colorless. AACD. Winter 2011,vol4,no.4

14. Refraction Clinical importance The shade should always be taken prior to the application of rubber dam. As rubber dam provides such an effective method of isolation so the teeth pushed through the dam will dehydrate quite quickly. Dehydrated teeth appear white and chalky. If the shade assessment was made at this point, then the final composite would be too light after the teeth have rehydrated after rubber dam removal. AACD. Winter 2011,vol4,no.4

15. Opacity Clinical importance The dentin layer is made up of opaque composite so that the hue of dentine can ben seen under illuminating condition through enamel layer . Trends Biomater . Artif . Organs, 25(4), 172-175 (2011). Color and Shade Matching in Dentistry.

16. It occurs when a substance absorbs and re-emits the light at a longer wavelength. In natural teeth, fluorescence is stimulated by ultraviolet (UV) radiation, which influences the tooth’s brightness producing a live appearance.  Fluorescence Braz. Oral Res. 2019;33:e088 1 Trends Biomater . Artif . Organs, 25(4), 172-175 (2011). Color and Shade Matching in Dentistry.

17. Natural fluorescence: Enamel has 2%fluorescence. (Organic component). Dentin composed of collagen and high amounts of amino acids like tryptophan, which emits fluorescence. making this substrate three times more fluorescent than the enamel.  Restorative Fluorescence: Europium, ytterbium, and other rare-earth elements are add on resin cements and ceramics that are designed to match the fluorescence of natural esthetic tooth structure. Clinical importance: Ceramic and resin restorations that lack a fluorescent agent appears as missing teeth when viewed under light change. Trends Biomater . Artif . Organs, 25(4), 172-175 (2011). Color and Shade Matching in Dentistry.

18. Opalescence Opalescence is the phenomenon in which a material appears to be of one color when light is reflected from it and of another color when light is transmitted through it. Low wavelength light Reflection Bluish opalescence High wavelength light Transmission Orange opalescence Opalescence is the phenomenon in which a material appears to be of one color when light is reflected from it and of another color when light is transmitted through it. Color: Implications in dentistry.Vimal K Sikri. JCD 2010. Trends Biomater . Artif . Organs, 25(4), 172-175 (2011). Color and Shade Matching in Dentistry.

19.  Type 1: Found in incisal edges that have opalescent halo closely related to the dentinal mamelons. It kind of opalescence presented by 58% of individuals . • Type 2: In this type of opalescent halo mamelons not penetrate between the dentin, extending over the incisal edge. It kind of opalescence presented por17% of individuals. • Type 3: Found in incisal edges showing diffuse halo opalescent, distributed randomly throughout the incisal edge. It kind of opalescence presented by 4% of subjects. • Type 4: In this type of opalescence opalescent halo presents mixed with some kind of pigmentation or characterization. It kind of opalescence presented by 25% of subjects. 18. Duarte J. R. S. Opalescence: the key to natural esthetics. Quintessence of Dental Technology 2007: 7–20.

20. COLOR IN DENTISTRY Coloring pigments : Coloring pigments are the inherent hues of an object. Primary Colors ( Red, Blue ,Yellow) These are the colors that are perceived when one of the RGB wavelengths is absorbed: Red is perceived when green is absorbed; yellow is perceived when blue is absorbed; and blue is perceived when red is absorbed.

21. Secondary colors : Orange, green, violet The secondary coloring pigments are formed by combining two of the primary colors: Red and yellow create orange; yellow and blue create green; and blue and red create violet

22. Complementary colors Complementary coloring pigment pairs are blue/orange, red/green, and yellow/violet. When complementary colors are added together, they neutralize each other and form gray. This is clinically significant because complementary colors can be combined to lower the value of excessively bright restorations

23. HUE Hue is synonymous with the term color . Used to describe the pigments of a tooth or dental restoration ( eg , red, blue, or yellow) Hue depends largely on what the visual system perceives to be the predominant wavelength of light reflected or transmitted from an object. Hue enables the distinction and differentiation among different colours DIMENSIONS OF COLOR

24. VALUE The dimension of value refers to the lightness of a colour . It is the achromatic vertical scale from black to white representing all shades of gray. It is usually communicated in terms of lighter or darker. A tooth that appears lighter or ‘brighter’ as a result of bleaching would display an increase in value.

25. CHROMA Chroma is related to variation in strength of the same color . The further away from the achromatic vertical axis, the higher the chroma (stronger, more intense). The closer the colour is to the achromatic (value) axis, the lower the chroma (paler, weaker).

26. Measurement of color There are several ways of describing and measuring color. In dental context, many color systems and shade guides are in use. Color systems Munsell system, CIE L*a*b system, RGB system, CMYK systems MUNSELL SYSTEM The most popular system for visual color matching in dentistry is based on the three-dimensional model devised by American artist Alfred H. Munsell in 1898.

27.   The Munsell color system consists of three independent dimensions represented cylindrically in three different directions. This cylindrical coordinate system takes into account the three dimensions of color: value, which increases from black at the bottom center to white at the top center chroma , which increases from the center outward for a particular color  hue , which is shown as specific colors arranged along the circumferential direction

28. Each horizontal circle is divided into five principal hues, namely, red, yellow, green, blue, and purple, and five intermediate hues, halfway between two principal hues. Value is along the central axis from 0 (black) to 10 (white) with neutral gray lying midway on the vertical axis. Chroma of a particular color extends horizontally from the central axis (least chroma ) outward to the circumference of the highest chroma for a particular hue.

29. Color is depicted by specifying three numbers,in the order of hue,value,and chroma The color is written as H V/C, which is called Munsell notation. For example, purple color of medium value and high chroma will be specified as 5P 5/10 (5P denotes the hue and 5/10 denotes the medium value 5 and a chroma of 10)

30. CIE L*a*b* SYSTEM This three-dimensional rectangular coordinate system is used in connection with color meters to evaluate the color of the object. It is based on the CIE L*a*b* color space in which L*is the lightness value, with values from 0 (black) to 100 (white) along the vertical long axis. a*and b*are the measurements of the red– green and yellow–blue horizontal axes, respectively. Negative a* is green while positive a* is red; similarly, negative b* is blue and positive b*is yellow

31. ELEMENTS AFFECTING COLOR ILLUMINATION Color can be neither accurately perceived nor correctly evaluated without proper illumination.

32. CLINICAL LIGHTING CHALLENGES The main reason for not getting accurate color matching in a clnical set up are 1.CONFLICTS IN LIGHTING Light coming in through a window mixes with the fluorescent light coming from the hallway and the color-corrected lighting in the dental operatory. Amid these various lighting conflicts, it is the task of the clinician to analyze the opposing teeth and to determine an accurate shade match

33. 2.METAMERISM The phenomenon of two objects appearing to match in color under one condition but showing apparent differences under another is termed illuminant metamerism .

34. CONTRAST EFFECT AND OPTICAL ILLUSIONS Contrast effects are visual phenomena that can alter the perception of color to some extent, as well as the ability to evaluate color in a clear, concise, and objective way. Simultaneous contrast Simultaneous contrast occurs when two colors are observed at the same time. When perceiving more than one color at once, the brain will attempt to achieve a harmonic balance of the colors . It can be value contrast, hue contrast and chroma contrast

35. Value contrast effect The same tooth appears increasingly lighter as the background becomes darker.

36. Value contrast effects have clinical significance when dealing with excessively inflamed gingival tissues . The dark value of the inflamed gingiva will trick the eyes into perceiving the tooth shade as being lighter than it actually is. As a result, the fabricated restoration will appear too dark once the tissues have healed

37. Hue contrast effect A color will be perceived differently when viewed in conjunction with various background or adjacent colors with contrasting hues

38. Chroma contrast effect The highly chromatic tooth appears more vibrant against the background that is low in chroma and less vibrant against the background that closely matches the chroma of the tooth.

39. Areal Contrast Effect A larger image appears lighter because the surface area is greater and reflects more light back to the observer. Conversely, a smaller object is less reflective and appears darker .

40. Spatial Contrast Effect An object closer to the observer will appear larger and lighter, whereas an object more recessed will appear to be smaller in size and darker

41. Successive Contrast Effect A positive (similar) or negative (complementary) afterimage of the colored tooth will be seen in the blank tooth after brief or long visual contact, respectively, with the colored tooth.

42. Dental shade guides The standard colour -matching tool used in dentistry for visual shade matching is the dental shade guide. Dental shade guides are tab-based tools fabricated from ceramic, resin or some other form of plastic or acrylic material. Commercial shade guides There are a variety of commercial dental shade guides available. Regardless of their number, they can be categorized into one of the following three main groups based on their design and concept: VITA classical A1-D4/Classical-keyed (empirical) VITA 3D-Master (evidence-based) Others (proprietary/Classical-proprietary) CONVENTIONAL VISUAL SHADE MATCHING

43. The VITA classical A1-D4 shade guide has been the gold standard for shade matching in dentistry since it was introduced in 1956. Per the manufacturer, the tabs of the VITA classical A1-D4 shade guide are arranged into groups alphabetically according to hue • A = Reddish-brown • B = Reddish-yellow • C = Grayish • D = Reddish- gray

44. The chroma and value for each hue group are communicated by a system of numbers after the letter designating the group—the higher the number, the darker and more chromatic the tab. Therefore, 1 is the least chromatic with the highest value, while 4 is the most chromatic with the lowest value.

45. Vita 3D-Master shade guide (VITA Zahnfabrik): There are three VITA 3D-Master shade guides: Toothguide , Linearguide , and Bleachedguide . Bleachedguide 3DMaster Specifically designed for bleach monitoring This scale includes 29 shades (15tabs with 14 interpolations) with color evenly distributed between tabs

46. Toothguide 3DMaster It is divided into six groups (0to 5, the first number in the number-letter-number marking) based on lightness,and within groups it is organized according to hue horizontally (L, M, R, onlyin groups 2, 3, and 4) and chroma vertically (1, 2, 3, the second number in the number-letter-number marking). The manufacturer-recommended protocol consists of three steps 1.Value determination 2.Chroma determination 3.Hue determination

47. Linearguide 3DMaster The VITA Linearguide 3D-Master (Fig 5-3) Has the same shade tabs as the Toothguide but a different design, and manufacturer-recommended shade matching is reduced to two steps: 1.Value selection 2.Chroma and hue selection

48. Other shadeguides Ivoclar Chromascopic system Like the classical A1-D4 shade guide, the tabs are initially divided based on hue, and then further intragroup selections are made. Chromascop differs in the use of a three-digit numbering system and the use of five groups of four tabs, as follows: • Group 100 = White • Group 200 = Yellow • Group 300 = Orange • Group 400 = Gray • Group 500 = Brown

49. Factors Influencing Shade Matching 1.Patient Expectations Generally, patient expectations fall into one of three categories: 1. Hollywood : White and straight restorations. These patients are generally very concerned and vocal

50. 2. Alfred E. Newman : Restorative design according to the clinician’s expertise. The vast majority of patients fall into this category, although most will lean toward one of the other two categories

51. 3. Naturalist : Restorations that look natural and blend in completely with the rest of the dentition. These patients are often the most dif cult to treat because they may have numerous craze lines, wear facets, diastemata , strange rotations, and speci c contours that will have to be matched

52. 1.Tooth Anatomy The clinician must match each of three vertical sections of the tooth: gingival, body, and incisal / occlusal .One of the first steps in analysis should be to determine whether the tooth is high in opacity or translucency The clinician must also fi nd the brightness (or value), hue, and chroma for each section of the tooth

53. 3.Shade matching conditions Lighting and environment For optimal results, shade matching should be carried out under color-corrected lighting with an ideal color temperature of 5,500 K (D55) to 6,500 K (D65) and with a color-rendering index (CRI) of 90 or greater Ideally, shades should also be checked in natural light. The level of light intensity is also important because correct illuminance (intensity of the incident light) can help reduce eye fatigue

54. Distance and position When matching a shade guide against the background of the oral cavity,adjacent teeth, gingival tissue, and surrounding skin, the comparison should be performed with the clinician’s eyes at tooth level, 25 to 35 cm (10 to 14 inches) away. This distance is appropriate for color comparison of the tooth and shade tab. Most suitable for visual color assessments in dentistry are 45 degrees/0 degrees or vice versa

55. Duration The retina exhibits adaptation if an object is viewed continuously for time periods greater than a few seconds, causing similar colorants to begin to look the same. This phenomenon necessitates glances of short duration to compare the color of a restorative sample with that of a tooth. Shade-matching trials should be limited to 5 to 7 seconds at a time to prevent eye fatigue.

56. Visual shade matching Method Pre shade matching steps Step1. Check color vision Prior to performing a shade-matching trial, it is imperative to screen the vision of the clinician for any color deficiencies . Step 2 . Use Colour Corrected Lighting For shade matching, light sources with a CCT (correlated color temperature) of 5500 K and 6500 K are recommended ; the colours are correlated to standard phases of natural daylight.

57. For best colour rendering results, light sources with CRI (color rendering index)of 90 or higher are recommended . Handheld lights, such as Rite-Lite 2 HI CRI and Smile Lite , which exhibit the recommended color characteristics are becoming increasingly popular for visual shade matching.

58. Step 3. Control Surround/Viewing Conditions Any surround conditions that may influence colour perception should be addressed prior to shade matching. Start by placing a neutral colour patient napkin over sparkling jewellery or bright clothes and having the patient remove reflective glasses and coloured lipstick

59. Shade Matching Steps 1.Perform shade selection prior to tooth preparation so as to avoid taking color of the teeth when dehydrated

60. 2.T e VITAPAN Classical Shade Guide has been used universally for many years. L.L. Miller (1993) suggests the use of two shade guides, one in which the tabs are arranged in order of their values (brightness)and the other in which the tabs are arranged according to their hues, with A and B shade tabs at either ends and C and D tabs in between, since C and D have hues between A and B in the linear rainbow

61. 3.First, wet the teeth lightly. Apply a glaze on the tabs and sweep the first shade guide (arranged with values) along the teeth to eliminate the obvious mismatches. You will probably end up with around two to three tabs that are similar to the teeth in their values, one with a slightly lower value and the other with a slightly higher value. Take photographs with these tabs alongside the teeth to determine the value

62. 4. Now select the hue with the second shade guide. Generally teeth are in the A or B hues, with many similarities. So let us assume that the teeth in question also have a hue of A or B. To choose the hue, use the A4 and B4 shade tabs which facilitate the process of elimination; since the chroma is very less in A1 and B1, it is very diffcult to select the hue

63. 5.  Determine whether the teeth have reddish, orangish (A shade), or yellowish (B shade) shades. T en hold the As or the Bs alongside the teeth to determine the level of chroma and take chroma images (Fig. 4.14D). If in doubt, choose the A hue, since most teeth are more reddish than B. (Almost 80% of natural teeth belong to the A family.

64. 6.After value and chroma , the translucencies and the characterization of the teeth should be noted (Fig. 4.6). To evaluate the proximal and incisal translucencies, ask the patient to turn from right to left to see the blue of opalescence in the translucent enamel

65. 7. Prominent surface anatomies and contours should be noted down, though a study model will depict these anatomies 8. It is also advisable to take shades of the gingi - val and incisal thirds separately owing to the convex tooth surface that reflects light only from the middle third during routine shade 

66. Macro-Mini-Micro Shade-matching Technique In the macro phase , the entire shade guide is used to select the potentially appropriate shade tabs or groups for further comparison.

67. In the mini phase , the previously selected tabs are narrowed down to select the best matches for gingival, body, and incisal areas.

68. In the micro phase , differences in value, chroma , and hue among natural teeth and the tabs selected in the mini phase are analyzed to fine-tune the selections.

69. Technology-Based Shade Matching

70. Several clinical studies have confirmed that computer-assisted shade analysis is more accurate and more consistent compared with human shade assessment. Advantages of high-quality shade-matching instruments include: • No influence of surroundings • No influence of lighting • Reproducible results • Easy documentation • Reliable data transfer Color -measuring instruments Color-measuring instruments include spectrophotometers, spectroradiometers , and colorimeters.

71. Colorimeter -Mechanism of action: lenses, and the filter helps to split a beam of light into different wavelengths allowing only the required wavelength to pass through it and reach the cuvette of the standard test solution. On reaching the cuvette the transmitted ray falls on the photodetector system where it measures the intensity of transmitted light. It converts it into the electrical signals and sends it to the galvanometer. ( Color: Implications in dentistry.Vimal K Sikri . JCD 2010.)

72. Advantage: Fast sensing. Consistent. Disadvantage: Color difference measurement is not as good as Spectrophotometers & Spectroradiometers. Trends Biomater . Artif . Organs, 25(4), 172-175 (2011). Color and Shade Matching in Dentistry. ShadeEye is an example of a colorimeter based on the natural color concept.

73. Mechanism of action: CCD The CCD is one type of sensor that is used to capture an image from light and translating it into digital information. Trends Biomater . Artif . Organs, 25(4), 172-175 (2011). Color and Shade Matching in Dentistry. Digital cameras as filter colorimeters

74. Digital SLR camera placed on the tripod to obtain image of the tooth sample placed on the 18% reflectance grey card. Adobe Photoshop software to obtain CIE lab values of the tooth samples imaged by the digital camera.

75. Disadvantages: Annals of Prosthodontics & Restorative Dentistry, July-September 2016:2(3):73-78 ADVANTAGES DISADVANTAGES During communication with technicians, dentists can present not only the dental morphology and colors, but also the surface texture, color distribution and other information under the intra-oral conditions. Intra-oral images with the reference shade tabs correctly positioned next to the teeth are also useful in shade matching. Unstable illumination in the images poses a big problem in intensity normalization during shade analysis. Meanwhile, the accuracy of tooth color matching in comparison to spectrophotometer has been not studied .

76. A spectrophotometer is made up of two instruments: a spectrometer and a photometer. The spectrometer is to produce light of any wavelength, while the photometer is to measure the intensity of light . A spectrophotometer is a refined version of a colorimeter. In other words, it functions the same way as a colorimeter but with added features. Spectrophotometers and spectroradiometers

77. A colorimeter uses a filter which enables a broad range of wave lengths to pass through on the other hand a spectrophotometer a prism or grating is used for the incident beam to split into different wavelengths . VITA Easyshade V is a contact-type spectrophotometer for shade matching and communication that averages color information of a 5-mm area in a single measurement. Easyshade V system (VITA)

78. Difference between photometer and radiometer: Spectrophotometers differ from spectroradiometers primarily because they include a stable light source. SPECTRO RADIOMETER

79. An understanding of the science of color and color perception is crucial to the success in the ever expanding field of esthetic restorative dentistry. Although limitations in materials and techniques may make a perfect shade selection impossible but a better understanding of psychophysiological processes involved in human color vision, color theory, and colorimetry should enhance an appreciation for the challenges associated with tooth shade selection. CONCLUSION

80. REFERENCES 1.Color in dentistry : a clinical guide to predictable esthetics / Stephen J. Chu, Rade D. Paravina , Irena Sailer , Adam J. Mieleszko . 2. Textbook of Operative Dentistry – Vimal Sikri 3. Annals of Prosthodontics & Restorative Dentistry, July-September 2016:2(3):73-78 4. Color: Implications in dentistry.Vimal K Sikri . JCD 2010. 5. AACD. Winter 2011,vol4,no.4 6. Trends Biomater . Artif . Organs, 25(4), 172-175 (2011). Color and Shade Matching in Dentistry. 7. Annals of Prosthodontics & Restorative Dentistry, July-September 2016:2(3):73-78 8. Sturdevant's Art and Science of Operative Dentistry: Second South Asia Edition