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Dental Tribune Middle East & Africa Edition | 6/2016 24 restorative Figs 8a to f: Portrait pictures taken more than eleven years after the placement of the restorations.Theestheticandfunctionalrequirementsofthepatienthavebeenandcon- tinue tobefullysatisfied. Conclusion Given the enamel-like properties of the glass-ceramic material, the mini- mallyinvasivemethodsusedforthis case provide a long-lasting approach to restoring the function, esthetics and biomechanics of the dentition while minimizing the damage to the biological structures (Figs 8a to f) [4, 6]. Beneficial clinical long-term results have been described and con- firmed in several studies [3, 8]. Par- afunctions, endodontically treated teeth and an adequate amount of enamel have, among others, been flagged as risk factors influencing the success of these restorations [3, 22]. Against such a background, the additive wax-up technique used here proved to be beneficial. Together with a diagnostic matrix, this technique enables a conserva- tive approach to tooth preparation and helps preserve the remaining enamel during preparation. In ad- dition, an in-vitro investigation has shown encouraging data regarding the stress distribution in ceramic onlay restorations [13]. It is, however, important to note that preparations should have soft and rounded tran- ◊Page22 Prof.DrDanielEdelhoff DirectorDepartment of ProsthodonticsLudwig- Maximilians-University Goethestrasse70 80336Munich,DE OliverBrix InnovativeDental DesignOliverBrix Kisseleffstrasse1a 61348BadHombur,DE Oliver-Brix@t-online.de daniel.edelhoff@med.uni-muenchen.de Dental Photography. Part II Protocol for shade taking and communication with the lab ByDr.EduardoMahn,Chile Abstract Part I of this article discussed the ba- sic equipment that is necessary for dental photography. In addition, a few examples of pictures taken that were better than others for the same situation were also shown. In part II, a protocol of taking digital photo- graphs will be presented which has been of great help to the author, spe- cifically in achieving the right shade andvalue. It is based on standardized pictures thatshouldbetakeninordertoshow certain individual characteristics of the patient to be treated and stand- ardized comparisons of the shade tabsandthenaturaltoothstructures in order to give the technician more information than the usual A2 or A1 writtenonapieceofpaper. Shadetaking Theevolutionindigitalphotography and the possibility of taking pictures andevaluatingthemimmediatelyas well as almost instantaneous access of the information by someone lo- catedoff-siteinthesamecityoreven another country, we have a great resource available that can help us achieve the right shade of our indi- rect restorations. Standardized high quality photographs are also an ad- vantage when the shade is taken for a direct restoration - for example a directveneeroraclassIV. In this case a picture can really help the clinician identify the opalescent areas and the halo effect of the adja- cent tooth, before re-doing the resto- ration(Figure1). Dental shade taking at the dental lab or in the dental practice can be frus- trating as most dentists do not really know how to use the shade guide when they finish their undergradu- ate studies. In particular, if work has to be redone, because the clinician does not know what was done incor- rectly wrong or how to obtain the rightshade. Dentalshadeguidesareusedbyden- tists,dentalassistantsanddentallab- oratory technicians to communicate propertoothcolor,translucency,and brightness. However, many variables come into play no matter what system you de- cide to use. Before even starting to think about shade taking; you need to answer an extremely simple and obvious question: are you using ex- actly the same shade system as the lab? There are many shade taking systems available, with variations in the shades between different manu- facturers, even though the concept maybethesame. They are also manufactured from different materials with different optical properties. For example, some labs are familiar with the Chromascope system, most of the dentists with the A-D shade guide, while the younger generation of dentists learned with the 3D master shade guide. (Figure 2) The role of a shade guide is to help standardize the perception and so facilitate the communication in order to match the shade of the natural teeth with therequiredrestoration. Shade guides are not a perfect rep- resentation of what is actually seen but are close enough to identify a range of tooth colors. Eyes are still the best tool for identifying and communicating the correct dental shade. Tooth color can be referred to as being an A1 or A2, or between a B2 and B3 when describing the respec- tive tooth closest to the one being restored. It is always best to get the patient to the dental lab and have a custom shade taken, if possible, par- ticularly for the more difficult cases. However, in most of the cases this is not possible, due to unwillingness of the patient to spend time going to the lab, or the location of the lab not beingincloseproximity. The use of shade guides should be used in conjunction with digital photography.Ifnodirectlightispro- jected to the mouth and the shade tabs, the main light source will be the flash of the camera, which has always the same temperature (be- tween 5500° and 6000° K) and can be used by the dentist in the clinic and the technician in the lab. When pictures are taken under different light conditions, the variations be- tween the same shades can be con- siderable. A good photo for both the dentist and the lab technician can be emailed so that they are both look- ingatthetoothcolorunderthesame conditions. When the technician comparesthecoloroftherestoration with the shade guide, he can take a picture that will create an image to be used as a comparison under the same light conditions as the natural teeth in the image sent by the clini- cian.(Figures3-5) Due to the flash of the camera, the technician can then compare, under the same light conditions as the cli- nician,whethertherestorationslook similar to the original shade tab sent by the clinician. ( Figure 6, Veneers byCDTJuergenSeger,Liechtenstein) ToothColorBasics Color has two basic characteristics: Hue and Chroma. Natural tooth color also displays these same char- acteristics. Hue can be defined as the actual color such, as yellow or gray. Chroma is the intensity of that color and is sometimes called saturation. Hue and Chroma are typically rep- resented by a shade guide in terms of which color comes closest to the actual tooth being measured. For example, shade guides will have a range of A1 to A4 or B1 to B4, plus C andDshades.(Fig17c) Valueisthebrightnessofatooth.Itis therefore given a separate classifica- tion than color when communicat- ing shade. Teeth also exhibit translu- cency and can be measured by how much light can pass through differ- ent sections of a tooth. Shade taking problemsarisebecausemostnatural teeth are not an exact match to a shade guide, nor do shade guides ad- equately express tooth translucency Figure 1:This picture will help the clinician to under- stand the challenge of reproducing the opalescent areasand thehaloeffect at theincisal third. Figures5:Differentappearanceoftheshadetabsun- derdifferent light conditions. Figures3-4:Different appearanceof theshade tabsunderdifferent light conditions. Figures7and8:Mayordifferencesintheappearanceofthesameveneersteeth11and21,duetotheuseorlack oflipstick.(Thanksfor thepictures toCDTJuergenSeger,Liechtenstein) Figure 2: Example of different shade guides showing thesameshade.Thedifferencesareobvious. Figure 6: The technician should always check the fi- nal appearance of the restorations with the use of the natural die materials shade guide on order to come to theoptimumresult. ÿPage 25 sitions to prevent stress peaks from occurring [1]. In recent years, the au- thorsofthisreporthavemainlyused glass-ceramic onlays based on lith- ium disilicate in conjunction with the staining technique [5, 7]. Given its increased strength, this material allows the minimum thickness to be reducedbyonethirdtojustoverone millimetre, further increasing the amount of tooth structure that can bepreservedduringpreparation. Given their extremely high strength and optimal marginal integrity, glass-ceramic onlays appear to be ideally suited for restoring the func- tion, esthetics and biomechanical properties of abraded and eroded posterior teeth. They offer an op- portunity to circumvent traditional prosthetic measures that are more invasive and involve higher biologi- calcosts[6]. Literature available from the editors onrequest