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Journal of Prosthetic Dentistry

Optimized digital shade calibration technology for the restoration of a single central incisor

      Abstract

      Predictable shade matching and communicating shade information to the dental laboratory technician have proved to be a capricious undertaking. Numerous confounding variables exist for the observer—which may be extrinsic (such as light source and background color), intrinsic (such as genetics and eye fatigue), or a combination of both. To address these shortcomings, low-cost, easy-to-operate, color analysis instrumentation and software programs have been engineered for objective shade selection and precise color analysis. The shade matching protocols that now exist have made even the most challenging esthetic treatments predictable for both the clinician and the dental laboratory technician.

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      Summary

      The demand on the contemporary dental practitioner to deliver life-like, indirect anterior restorations has intensified over the years as discerning patients have become increasingly aware of the reality that teeth make a significant impact on the overall esthetics of their outward appearance (Fig. 1).
      • Burki Z.
      • Watkins S.
      • Wilson R.
      • Fenlon M.
      A randomized controlled trial to investigate the effects of dehydration on tooth colour.
      One of the primary challenges encountered by the restorative dentist and dental laboratory technician is the ability to meticulously communicate and replicate the nuance parameters of tooth shade characteristics.
      • Mahn E.
      • Tortora S.C.
      • Olate B.
      • Cacciuttolo F.
      • Kernitsky J.
      • Jorquera G.
      Comparison of visual analog shade matching, a digital visual method and a cross-polarized light filter, and a spectrophotometer for dental color matching.
      Figure thumbnail gr1
      Figure 1Initial presentation of 32-year-old patient with unesthetic composite resin restoration of fractured left maxillary central incisor. A, Portrait view. B, Smile view. C, Frontal view.
      The use of dental color shade guides and intraoral photographs captured with a digital single-lens reflex (DSLR) camera is commonly used to match teeth to artificial materials; however, the process has been reported to be inconsistent and subjective.
      • Hatırlı H.
      • Karaarslan E.Ş.
      • Yaşa B.
      • Kılıç E.
      • Yaylacı A.
      Clinical effects of dehydration on tooth color: how much and how long?.
      Disparity in color between a fixed prosthesis and the adjacent natural dentition is unfortunately commonplace and has been reported to occur in as many as 63% of ceramic restorations.
      • Bergman B.
      • Nilson H.
      • Andersson M.
      A longitudinal study of Procera ceramic-veneered titanium copings.
      To further complicate this process, various factors have been implicated in the struggle for precision in the shade selection process, including rapid tooth dehydration,
      • Suliman S.
      • Sulaiman T.A.
      • Olafsson V.G.
      • Delgado A.J.
      • Donovan T.E.
      • Heymann H.O.
      Effect of time on tooth dehydration and rehydration.
      changing ambient lighting conditions,
      • Carsten D.L.
      Successful shade matching – what does it take?.
      operator experience,
      • Okubo S.R.
      • Kanawati A.
      • Richards M.W.
      • Childress S.
      Evaluation of visual and instrument shade matching.
      and visual genetics.
      • Wagner S.
      • Rioseco M.
      • Ortuño D.
      • Cortés M.F.
      • Costa C.
      Effectiveness of a protocol for teaching dental tooth color in students with color vision impairment.
      To overcome the shortcomings and frustrations associated with human visualization and acquisition of analog shade tabs, utilizing instrumental methods, such as spectrophotometers and colorimeters, albeit expensive and requiring additional training,
      • Gurrea J.
      • Gurrea M.
      • Bruguera A.
      • Sampaio C.S.
      • Janal M.
      • Bonfante E.
      • et al.
      Evaluation of dental shade guide variability using cross-polarized photography.
      has been suggested because of their objective shade matching capacity.
      • Chu S.J.
      • Trushkowsky R.D.
      • Paravina R.D.
      Dental color matching instruments and systems. Review of clinical and research aspects.
      The basis for this digital presentation was to demonstrate the straightforward communication between a dental clinician and a dental laboratory technician in the development of esthetic dental restorations. Successful collaboration was achieved by utilizing a novel colorimeter (Optishade StyleItaliano; Smile Line), a smartphone application (OptiShade App iOS; StyleItaliano), and a shade-matching software program (Matisse Software; LabMatisse; Fig. 2) that are cost-effective and uses a predictable shade-matching technology that can be effectively operated without traditional shade guides or DSLR cameras (Fig. 3).
      Figure thumbnail gr2
      Figure 2A, Optishade StyleItaliano colorimeter, Apple smartphone, and OptiShade App provide intuitive user interface and enable use by auxiliary staff with minimal training. B, Smartphone images obtained convert color information into CIELab values and facilitate conversion into analog shade guide values. C, Matisse Software uses predictive artificial intelligence models to generate “paint-by-number” ceramic recipe for the dental laboratory technician. Formula derived from tooth preparation’s available space, preparation shade, and target shade of tooth to be matched.
      Figure thumbnail gr3
      Figure 3A, Color delta model fabricated to simulate appropriate shade of surrounding oral structures, including preparation shade, and to gauge influence of light transmission through zirconia framework. B, Dental laboratory technician able to objectively compare side-by-side clinical and laboratory images and CIELab values of target tooth and definitive restoration. C, Texture created on definitive restoration ready for delivery.
      Traditional clinical and laboratory methods in the treatment planning and fabrication of esthetic restorations were reviewed. Contemporary, collaborative protocols employing the most-current dental shade matching technology were outlined for 2 patient treatments involving the restoration and single-visit delivery of single central maxillary incisors with complete-coverage high-strength ceramic crowns for a natural tooth (Fig. 4) and an endosseous implant.
      Figure thumbnail gr4
      Figure 4Completed restoration. Definitive layered zirconia restoration demonstrates seamless integration and harmonious esthetics. A, Portrait view with Duchenne smile at single-visit delivery appointment. B, Smile view. C, Frontal view.

      Supplementary data

      References

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