Shade-taking for restorations
Shade-taking for restorations
Mimicking the positioning, contours and optical surface properties of adjacent and opposing natural teeth as realistically as possible is an important part of integrating dental prostheses inconspicuously into the mouth. The optical surface properties are summarized by the term "tooth shade" despite the fact that they include a wide range of parameters such as shade, shade gradient, brightness, shade saturation, translucency (light shimmering through light-scattering material) versus opacity (due to scattering of light), fluorescence or phosphorescence (light emission due to, e.g. UV light), glaze (due to reflection of light).
The virtually infinite spectrum comprising millions of naturally occurring tooth shades subjectively perceptible to the human eye can be reduced to a few standardised shades (clearly defined and described for objective documentation and communication) and only incur minimal aesthetic sacrifices. These are then incorporated into so-called shade guides (mostly one-dimensional/linear, rarely multi-dimensional, encompassing various parameters) such as for prefabricated denture tooth. These shade tabs are usually contoured like teeth, made of the restorative (e.g. composite or porcelain) and used for comparing with patients' teeth and/or restorations.
Shade guide
Shade guides are also available in gingival shades for imitating soft tissues such as mucosa.
As each specific surface appears differently (metamerism) when illuminated with light of differing intensities or wavelengths (sun, cloudy, dawn, artificial lighting), in order to achieve predictable results wherever possible shade-taking must be carried out under reproducible, standardised lighting conditions. To achieve these, various technical aids such as identical ring lights for dentist and technician, cameras with white balance or special electronic devices which measure spots or use standardised photos for "surveying" the various areas of the tooth (such as the incisal, dentine, cervical and proximal regions) and displaying the results to correspond with standard shade guides are employed.
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Word of the day
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| professional society | Fachgesellschaft |
Focus text of the month
Endodontics Endodontologists are… Endodontics Endodontologists are dentists specialised in endodontics. Endodontics is a section of conservative dentistry and therefore always supports tooth conservation. This includes (direct) pulp capping of exposed pulp area, apicectomies but mainly root canal treatment. Endodontic treatment is indicated with irreversible pulpitis, destruction of the pulp due to accidents or infection as well as persistent or re-occurring bacterial colonisation of root canals that have already been treated or filled (revision).
The initial aim (practical) is the complete elimination of diseased tissue, foreign material (e.g. existing root canal filler material) and pathogens from the root canal system. The chemical methods include antibacterial and/or tissue-dissolving solutions (e.g. chlorhexidine, EDTA, sodium hypochlorite, hydrogen peroxide). Machine or manually operated steel or nickel titanium root canal instruments are used for mechanical preparation, i.e. excavation, smoothing, cleaning and extension of the (main) root canals. Both methods in combination form chemomechanical preparation. Medical temporary fillings (e.g. with calcium hydroxide or chlorophenol camphor menthol) can be used for further reduction of bacteria. Finally, the prepared main root canals are obturated, i.e. using a root canal filling (e.g. consisting of gutta percha posts and root canal cement) filled, sealed and covered using an adhesive filling and/or a crown.
In the final outcome the treated tooth should heal long term without any discomfort/symptoms and there should be no pathological changes of the apical alveolar bone (detectable on the X-ray). The probability of success of endodontic treatment has greatly increased in the past two decades, particularly due to the increased use of operating microscopes and microsurgical techniques and is generally given as 90%. In addition, successes have been achieved in the coverage (including iatrogenic) of perforations or the removal of fractured instruments or cemented posts from the root canal system.
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Access to the pulp chamber
Filled root canals 25, 26, 27
Master point - The first guttapercha point