BULETINUL INSTITUTULUI POLITEHNIC DIN IAŞI

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56 Irina Grădinaru et al. Another modality for tooth shade selection is the use of photography in combination with a spectrophotometer. In the last years in dental practice have been introduced different colorimeters and spectrophotometers that can determine tooth shade by direct application to the patient tooth (Fig. 5). Fig. 5 – Spectrophotometer VITA EasyShade (http://www.agd.org). VITA EasyShade spectrophotometer provides a determination of tooth hue according to lighting conditions. Their accuracy is difficult to evaluate and, for some instruments, depends on the angle at which the instrument is positioned and other operator variables. The cost of these instruments is very high and limits their use in most dental offices. For determining the color of the natural teeth are used shade guides and so, the artificial substitute restorations will have similar color and esthetics. The shade guide “VITAPAN classical” is the most widely used shade system with more than 40 years of world-wide recognition (Fig. 6). Fig. 6 – Shade guide “VITAPAN classical” (http://www.globaldentalsolutions.com/shadeguides.html). The shade guide “VITAPAN 3D-MASTER” represents the results of many scientific and clinical researches and is considered the consequent further development of the “VITAPAN classical”. The VITAPAN 3D-MASTER Shade Guide features a systematic structure in accordance with a colorimetric classification principle. It incorporates all three dimensions (3D) of color perception: Value (Lightness Level), Chroma (Color Saturation), and Hue (Fig.7). A shade guide must have some characteristics represented by: a logical arrangement and a adequate distribution in color space matching with natural
Bul. Inst. Polit. Iaşi, t. LVIII (LXII), f. 3, 2012 57 teeth, a inherent consistency among shade guides, and matching between shade guides and the dental materials (eg. porcelains, resin composites or dentures). Fig. 7 – Shade guide “VITAPAN 3D-MASTER” (http://www.globaldentalsolutions.com/shadeguides.html). Unfortunately, the currently available shade guides do not have all the mentioned properties and not all shade guides are fabricated from the dental materials to which they will be matched (O’Brien, 2008). For the dental office and laboratory, shade matching is a very complex process (Fig. 8). Fig. 8 – Schematic representation of the shade-matching transmission after O’Brien. It is necessary to respect some recommendations: i) use the manufacturer shade guide for fabricating the dental restoration; ii) remove the individual shade tab from the guide and hold it close to the tooth for shade matching; iii) respect the manufacturer's recommendations for preparing the surface of the tooth for shade matching; iv) match the surface texture of the dental restoration to that of the remaining dentition as closely as possible; v) choosing a neutral chromatic environment; vi) the choice of color is always done at the beginning of the treatment session; vii) lighting conditions similar to daylight; viii) remove lipstick and makeup from the face of the patients; ix) patient mouth should be at the doctor eye level; x) the choice of color, by comparison, must not exceed 5 seconds, to avoid fatigue of the cone cells;
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BULETINUL INSTITUTULUI POLITEHNIC D
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BULETINUL INSTITUTULUI POLITEHNIC DIN IAŞI

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