Gate Dental Services Ltd
Analysis
Dock Road, Galway. Ireland.
Tel: 00353 91 547 592 W: www.gatedentalservices.com E: info@gatedentalservices.com
Methodology
Simplicity Introductory Video Click here
Documentation
Communication
Features and Bene;its Of SpectroShade Shade Determination Independent of Ambient Light Hue Value Chroma (Lab , Lch) Objective Photospectrometer Readings of Whole Tooth
Can be Completed by Auxillary Staff VeriXiable by Laboratory Glossy or Matt Photograph of Reference Tooth Dimensional Measurements (Length, Width, Area, Ratio.) Multiple Shade Guide References Available Pre/Post Bleaching Documentation Enables “Vitality” Colourimetry
Glossy image shows light reXlection patterns Matt image
One shade analysis Three band analysis – band width can be altered
Mutiple shade analysis
LCH analysis of selected area
Reselect different area
Option for different Lab analysis
Shade Analysis of Vita A 3.5 Shade Tab
Summary of analysis
Report of Analysis
Can be printed for laboratory
Can be emailed
Colour Analysis, Documentation and Communication Our 9 year experience with a Photospectrometer in General Practice Dr Paul Moore BDS. Galway. Ireland.
Figure 1 Central Incisor Veneers
Introduction In dental practice the demand for correct colour analysis, documentation and communication has always been a requirement. This is not so difXicult where all six anteriors can be replaced simultaneously and the colour for all six can be selected in unison, but if a single crown has to be matched to the neighbouring teeth most clinicians would consider this to be more of a challenge.
Replicating the analysis is another challenge altogether, but to allow the technician a reasonable chance to deliver restorations that will match in colour we need to Assess the colour, Document our Xindings and Communicate our records accurately. Only with such a prescription can the technician (who in most cases does not have the patient present) have a reasonable chance of interpreting and delivering your requirements successfully. We need to determine colour of teeth for many reasons, but today I would like to look at two applications. 1.Documentation of colour before and after bleaching to evaluate short and long term colour changes and stability. 2.Successful communication with the dental technician for manufacture of crowns and veneers. 3.Cerec dentistry is diferent. We have to analyse the colour and duplicate it but when completed chairside we do not have to communicate this to a third party, but there are still issues. 4.The Spectroshade allow us to determine the distribution of shades throughout the tooth and the value and chroma of the best block to use
The human eye’s perception of colour is also unfortunately very sensitive (the patient can tell you if you have got the colour right or wrong when comparing your crown to the neighboring tooth!) The table below summarises how we analyse colour Unfortunately the visual interpretation of the true colour is dependant on the difference in perception of the above according to many variables. Some of these we discus below. Ambient light. Is the light source from natural daylight, halogen light, LED, “colour corrected light source”? Is it diffuse daylight? Is it midday direct sunlight? What is the angle of incidence of the light and the observer? What colour are the walls of your surgery? Colour as we have said is a measure of the reXlection / absorption of the light from a material. Therefore varying the light intensity or wavelength will vary the colour. Operator sensitivity. The physiological perception of the “colour” will vary during the day according to tiredness of the operator and exposure to working light source. This is acutely exempliXied if one walks from direct sunlight into artiXicial light and your eyes take time to adjust to the colour, shade and the intensity. Surrounding structures. Does the patient have their teeth apart or closed? Is a photographic black contraster being used? As implied the black contraster will change the perception of colour.
The contrast between neighbouring teeth, inXlamed or pigmented soft tissues, or even patients wearing red lipstick will inXluence perception. Photographs taken with black background will always appear lighter. The chroma is effectively increased. Look at the grey bar in the middle of this picture, what colour is it.
… it’s a uniform grey! Don’t believe me , then block out the top and bottom areas. This is a nice demonstration of how the human perception of contrast and “colour” can be inXluenced by the surrounding structures. With this in mind I want to propose that where possible Xinal staining and characterisation should not be done on a model. The surrounding colours are wrong.
Figure 2 These three photographs are all identical, same flash, exposure aperture, but with varied backgrounds .
Figure 3. Same light source but taken at different angles. The ability of the dentist to measure these factors is determined by the tools available to him. Visual interpretation of colour and comparison to commercially available “shade guides” are subject to many variables. This is why they are called “guides”. Although “calibration” of the eye / brain and this interpretation is subject to operator variables, the use of commercially available shade guides is the most commonly used technique for analysis. However these shade guides themselves have a variation in colour from the tip to toe of the tooth. Enclosed is a SpectroShade analysis of my Vita A3.5 shade tab. Your shade tab will be different. The main body of the shade tab is identiXied as A3.5 but a three part analysis shows that the neck is D4 and the incisal edge is B4. The multiple analysis shows the variety of shades within the tab. The experienced clinician or technician judges the colour of the tooth from the middle third of the shade tab but this demonstrates nicely the difXiculties working with tabs composed of more than one colour.
This complicates the interpretation of the colour. Nor does the shade guide quantify hue, value, transluscency or charcterisation of the tooth to be measured. Ideally using customized tabs of the end restorative material, in the thickness of the end restoration, should be used to replicate the aesthetic properties of the proposed restorative material.
Figure 4. Analysis of the Vita A3.5 shade tab, showing multiple shades.
TRADITIONAL DOCUMENTATION The next problem is how to record the shade analysis that you have painstakingly assessed. Shade selection from the selected target teeth should always be done at the beginning of an appointment, not after the patient has had their mouth open and dehydration has altered to colour characteristics of hue and chroma during the preparation. The technician does not have the advantage of having the patient present while he is layering his porcelain to replicate your prescription. Even if he has taken the shade in the laboratory he has to record his own analysis in a manner that allows him to recall the details, once the patient has left. He also has the problem of veriXication of the Xinal shade. Communication in practice is often by drawing the details on a lab ticket. We looked at the variety of dockets in a working dental laboratory and the range of detail varied from simple diagrams to works of art. The ticket is the Prescription and has to convey the accuracy of the shade selection. Depended on the subjective assessment of the comparison of the shade tabs to multiple points on the tooth to generate a colour map, the ticket also has to convey Morphology, Microsurface, Texture, Translucency, Characteristics, Luster. This is a big ask for the language ability and artistic skills of the dentist. In Figure 4. I have drawn one “Lab Ticket” with three samples of the level of detail that might be seen in a commercial dental laboratory. Photographs are certainly a great help allowing the technician to see the relative comparison to the surrounding teeth. Fig 5. They will convey the surface texture, the reXlectivity and luster. Characterisations can be recorded and the
shade directly written onto the printed image. But note the printed image will not duplicate the exact hue, chroma and value due to variations in printing inks and printing paper and even in computer monitor calibrations. However anything that gives more information for the technician will facilitate more accurate production of an improved Xinal restoration. SPECTROSHADE MICRO HOW DOES IT WORK?
The use of spectral data analysis has been shown to improve the analysis, documentation and veriXication of colour. Using the “SpectroShade Micro”, a hand held spectrophotometer gives us control of the ambient light with a dedicated independent light source to allow consistent veriXication of colour. A spectrum of visible light is directed at the tooth at 45 degrees from both sides, and recorded by two cameras. One camera is full colour and and a full analysis of the entire surface of the tooth is recorded measuring the hue, the value, the chroma and the translucency of the tooth using the CIE ( Commission Internationale del’Ecleraige) L*a*b* coordinates. The other camera is black and white. This gives a mathmatical record of the components of colour, quantifying L* (luminosity) a* (quantity of green-red) and b* (quantity of blue-yellow) which can be related to the chosen shade guide for the chosen restorative porcelain. Readings for hue value and chroma are recorded and can be pinpointed to any area of the tooth.
The SpectroShade also gives the option of a matt rendition or a lifelike gloss image which supplements any broader photographic information, giving a breakdown or prescription of detail for the technician to work from. This information can be printed or emailed to the technician. If the technician also has a SpectroShade Micro, he too can image the crown he is making and use this to verify the shade distribution of the crown before returning the Xinished unit to the clinician. With experience, clinicians and technicians should Xind the improvement in communication signiXicant but the end result will still be a sum of the total of your skills clinically to determine factors such as the thickness or depth of porcelain, and the materials and the skills and experience of the technician. EXAMPLES OF CLINICAL USAGE NON VITAL BLEACHING The UR1 UL1 were non vital following a sporting injury on a 14 year old. The UL1 had fractured in the apical third. We dressed the canal with calcium hydroxide, then completed root canal therapy, obturating the UL1 with MTA Xlooded into the fracture zone. In this case we elected to bleach the tooth internally one month after the obturation to ensure the
Figure 5. Photograph of shade tab for documentation and communication.
endodontic therapy was settling. Initial bleaching was successful but seven years later despite “successful” endodontics the clinical crown had discoloured further. For deXinative documentation, the difference can be recorded and compared back to at a later date. The pre and post bleaching images are taken and shown below with the pre and post bleaching spectrometer reading.
Figure 4. Diagram showing the range of details a technician may have to work from.
Figure 8 Discoloured non vital UL1
Figure 9 SpectroShade analysis of the discoloured UL1
Figure 7 a. Exploration of 14 year old, traumatised incisors. b. Obturation with MTA and GP. c. Seven years later.
VITAL BLEACHING Vital Bleaching is becoming one of the most popular “cosmetic treatments”. We always discuss and offer the option to patients prior to any other anterior restorative work, composites, crowns, veneers dentures or implants. This is to avoid patients asking for bleaching after we have completed restorative work, but is completely elective. Again we always take pre and post bleaching SpectroShade measurements for documentation. This negates what we call the “All over Suntan Effect”. We would Xind that patients although delighted with the shade change initially, would return a year later and felt that the bleaching effect had changed. Unless there is a reference point such as an existing restoration that can act as a visual constant ( such as the bikini line with an “all over body tan”) the patient’s subjective assessment is hard to disprove.
Prior to the SpectroShade analysis this was particularly difXicult to quantify. Now we can quickly advise the patient and quantify any changes that have or have not occurred. This is good for the conXidence of the patient, the dentist and the practice reputation. Note the diference in detail between the A2 shade tab and the comparison with the SpectroShade analysis.
Figure 12. Pre bleaching assessment with shade tab for comparison.
Pre bleaching assessment with SpectroShade
Post bleaching assessment with SpectroShade
Gate Dental Services Ltd www.thedentalorganiser.com
Dock Road, Galway, Ireland. 00353 91 547 592
Dr Paul Moore ( Director ) 00353 87 682 4551 Drpmoore@mac.com
Hazel Hendy ( Director ) 00353 87 236 8451 hazelhendy@mac.com
International Distributors of MHT SpectroShade