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R. G. Chadwick British Dental Journal 2011; 211: E23

Editor's summary

With the renewed debate on the ethics of cosmetic dentistry coming to the fore, it is pertinent to view this paper as central to the issue of clinical effectiveness and technical competency.1 From a patient's perspective the match of a tooth-coloured restoration to the existing and adjacent tooth tissue is crucial in their assessment of the success of the outcome.

This paper asks some fundamental questions about our ability as clinicians to perceive colour matches and shade assessment, the accuracy of shade guides provided for transfer of information and reproducibility from surgery to dental laboratory and the hue of the underlying tooth preparation. One might be forgiven for wondering whether, with so many variables, it is ever possible to arrive at a satisfactory, aesthetically pleasing result. The fact that it clearly is, is a testament to the successful collaborative nature of the dental team; materials researchers, manufacturers, practitioners and technicians.

Aside from the technical issues the paper once again draws our attention to the often discussed but frequently poorly observed need for good co-operation between dentist and technician. Although unquestionably now members of the dental team since their inclusion as GDC registrants in the role of Dental Care Professionals, technicians have historically often been at a physical distance from the surgery and as such have suffered greater isolation than other team members who have direct patient contact. This has often lead to breakdowns in communication, lack of understanding and consequent blame and recrimination where restorations or appliances have been found wanting.

Mutual appreciation of skills, knowledge and experience in a professional's given field is not just essential in the provision of maximum patient care it is fundamental to good practice and to continuing education and development. Greater understanding of the processes both chairside and at the bench enable us to make the very best of the art and science of dentistry.

The full paper can be accessed from the BDJ website ( www.bdj.co.uk ), under 'Research' in the table of contents for Volume 211 issue 11.

Stephen Hancocks, Editor-in-Chief

Author questions and answers

1. Why did you undertake this research?

In recent years heightened patient aesthetic expectations, together with the availability of new porcelains, has brought about a re-examination of techniques for shade taking. In the authors' experience the focus has been exclusively on the shade of the final restoration, with scant, if any, regard being given to the underlying preparation. It is, however, well accepted that where a crown is exclusively made up of porcelain, shine through of the underlying tooth preparation can compromise adversely the aesthetics. To address this it has been suggested that the dentist should also communicate the shade of the underlying preparation to the dental technician. If adopted this represents a paradigm shift in procedure. This work sought, therefore, to examine means of achieving this together with factors that could affect potentially the outcome.

2. What would you like to do next in this area to follow on from this work?

This work indicates that communication of the shade of the underlying preparation is both possible and reproducible. It would be interesting to study the opinions of all members of the dental team, and the patients for whom all-ceramic crowns have been provided, as to whether the additional steps involved produce tangible aesthetic benefits. It would also be of interest to learn if knowledge of one's colour matching ability can assist in improving shade taking performance.

Commentary

This paper by Alomari and Chadwick evaluated variables possibly associated with shade matching quality: type of shade guide, shade matching methods (one shade or two shades selected), and subjects' gender, age, shade matching experience and profession (dentists and laboratory technicians). The utilised colour-corrected light was of appropriate colour temperature (5,500K), colour rendering index (92) and illuminance at shade matching area (approx. 1,400 lx), while the neutral light grey card was a correct choice to prevent eye fatigue. Shade matching tests for individuals that determined what is the best match for each prepared tooth and shade guide were also well planned, although instrumental colour measurements would certainly complement their findings and the overall merit of the study.

The literature is fairly consistent when it comes to the positive influence of colour education. The same is true for shade guides with better coverage of tooth colour range and distribution. This study reported that one shade guide exhibited greater reproducibility and a lower percentage of incorrect matches, but it should be noted that it is reasonable to expect this for a shade guide with fewer tabs (and therefore fewer choices and greater colour differences among the tabs). As far as the influence of tab arrangement is concerned, some studies reported that it influenced shade matching performance, while others had the opposite findings. This study found the same percentage of exact matches for A to D arrangement and value scale of Vita Classical, whereas the percentage of close matches was higher for value scale.

The literature is also equivocal regarding some other potential shade matching variables: a majority of studies reported that gender, age, experience and profession did not influence shade matching quality, whereas shade matching conditions and method did. In this study, gender and age did not influence shade matching results, whereas experience and profession did.

Finally, the FM-100 Hue test is a non-dental, conventional colour discrimination test, and according to several publications, its results correlate to a certain extent with the findings obtained using customised dental tests. In general, there would be no harm if both tests were used in dental colour research.

It is interesting that the study design corresponds in many aspects to the new ISO Guidance on colour measurement,2 published after the execution of this experiment. Regardless of some wanting design details, the authors should be commended on their work in this important and complex yet sometimes neglected area.