Color Science 2 Fall 2024 Clinical Fixed Prosthodontics PDF

Course Title: Clinical Fixed Prosthodontics V Course Code: PRO 325 Topic of Lecture: Color science and shade selection Lecturer: Dr. Marwa Wahsh Post :Professor of Fixed Prosthodontics F A C U L T Y O F D e n...

Course Title: Clinical Fixed Prosthodontics V Course Code: PRO 325 Topic of Lecture: Color science and shade selection Lecturer: Dr. Marwa Wahsh Post :Professor of Fixed Prosthodontics F A C U L T Y O F D e n t i s t r y T h e F u t u r e S t a r t s H e r e F A L L 2 0 2 4 COLOR MATCHING VISUAL SHADE MATCHING Shade selection Shade selection sequence  Match shade prior to preparation (Tooth color increases in value when the teeth are dry)  Polishing to remove stains and debris.  Remove all distractions Shade selection sequence  Seat the patient in an upright position.  Observations should be made quickly.  Dentist should glance at a gray card to rest the eyes.  Scan the entire shade guide and eliminate the worst match.  Moisten shade tabs as well as teeth and never match under dehydrated condition. Shade selection sequence  If a decision cannot be made between two tabs → match the gingival portion, then the incisal portion. High Chroma & opacity Less Chroma & high value High translucency & lower value Shade selection sequence  Try viewing the tabs through half closed eyes → increases the ability to match value.  Verification of shade: On more than one occasion Confirm by a second individual as an assistant Clinical Tips for Ceramic Laminate Veneer Shade Selection  Take a photograph of the selected shade tab adjacent to the unprepared tooth structure as a reference shade for the technician.  Select the stump shade after the final tooth preparation. The restorations must compensate for the darker, greater chroma stump shade and are frequently fabricated higher in value and lower in chroma in the correct hue.  Dentin shade guide is used to communicate the color of the prepared tooth to the technician when a translucent ceramic is used Shade selection systems The Vitapan Classical: 1 to 4 - 1 is the least chromatic, 4 is the most chromatic. Ivoclar Chromascop:10 to 40 - 10 is the least chromatic, 40 is the most chromatic.ing numbers. Chromascop Classical VITA Shade Guide Arranged by: Decreasing Value & Increasing Chroma (1 --> 4) msmjfjfjjddsehdcjdcjdjcjdwcjw djhwh  Vita classical shade guide  Note that: Higher numbers are more chromatic and lower numbers have higher value, i.e. lighter.  So from left to right chroma increases and value decreases. Scan by Hue Groups A - Shades (Orange) Scan by Hue Groups B - Shades (yellows) Scan by Hue Groups C - Shades (grays) Scan by Hue Groups D - Shades (reddish-browns) Scan by Value Dark Values VITA Classical Shade Guide Arranged by Value Vita classical shade guide Shade Distribution Chart Limitations Non-Linear Progression of Shades in Vita classical shade guide 3-D Master Shade Guide 3-D Shades Groups Value Only 1 2 3 4 5 Chroma Hue Bleached shades Vita 3D shade guide  Now available:  0M1, 0M2, 0M3  Bleached shades represent the brightest value VITA Linearguide 3D-MASTER Step 1: Remove the VITA Valueguide 3D-MASTER from the top of the Linearguide. VITA Linear guide 3D-MASTER Make an initial choice using the Value guide. In doing so, you determine the correct degree of lightness 0 to 5. VITA Linear guide 3D-MASTER Step 2: Make a detailed choice within the determined degree of lightness from step 1 using the corresponding VITA Chroma / Hue guide. VITA Linear guide 3D-MASTER Helpful Hints for Using 3D-MASTER  Value is found in the “3” group in more than 50% of test patients  Start with the lightest (most diluted) Chroma and add intensity  Hue is found in the “M” group in more than 50% of test patients. A hue shift to Red or Yellow is not mandatory Some of the Limitations of conventional shade guides 1- Subjective determination of color. 2- Available shade guides represent only about 30 % of the color range of natural dentition. 3- Shade is acquired in 3 distinct zones (gingival, body and incisal) which is not precise. 4-Shade guide tabs are 4-5 mm thick compared to the thin porcelain used for the restoration. Instrumental color analysis  Color measuring instruments: ❖ Spectrophotometers: Measures the intensity of wavelength of received light; measures the spectral data. ❖ Colorimeters: Measures color by comparing it against a set of internal reference colors. Spot capture systems  Vita Easyshade.  ShadeEye NCC.  Shade star Vita Easy Shade  Easy grip  Small tip  Wieless  Rechargeable battery Complete-tooth capture systems  Provide a reading of the whole tooth to be matched:  ShadeVision  ShadeScan ShadeScan  Digital image capture  Windows-based Analysis Software  Digital standardized photographs can serve as an effective tool for shade matching.  Digital shade selection: 1. Acquisition of photographs with a digital camera at standardized parameters. A photo of the gray card is taken and used to set white balance for a sequence of photos. 2. An image analyzing software e.g. Adobe Photoshop CS software is utilized to derive L* a* b* values.  ClearMatch  Software to be used with digital cameras  Technology normalizes color images  Contains all major shade guide systems and allows custom guides to be added  Color recording using smartphones  Smartphones in combination with a gray reference card with known color parameters can be used to accurately record images in dental digital photography.  A photograph using a smartphone camera and external LED Video Light with the gray reference card and chosen shade tabs placed close to the tooth of interest.  Color recording using smartphones  After color correction, the image is adjusted and increase the contrast and decrease the brightness to a level that makes shade tab selection based on value discernible. With this setting, compare the shade tabs and select the tab with the closest value. ,,, Color recording using smartphones Digital photograph of selected value group shade tabs compared with determine chroma. Abraham G, Kurian N, Wadhwa S, Varghese KG. A smartphone application with a gray card for clinical shade selection: A technique. JPD https://doi.org/10.1016/j.prosdent.2023.01.016 Color recording using smartphones  Adjusting brightness and contrast for chroma selection reveals 1M2 as closest matched shade tab. A, Brightness decreased. B, Contrast increased. IPS shade navigation app Some of the Limitations of Digital shade guides;  Technicians and clinicians must have an understanding of color mapping techniques.  Training is required for use of such devices.  Some devices do not measure the entire tooth surface.  Some devices do not measure translucency , texture effects and subsurface color.