Research and Education
In vitro comparison of instrumental and visual tooth shade determination under different illuminants

https://doi.org/10.1016/j.prosdent.2015.06.004Get rights and content

Abstract

Statement of problem

While a considerable body of literature deals with the comparison between visual and instrumental tooth color determination, in most of these studies either the number of color specimens or the number of examiners is too small to allow for a general statement about such a subjective method as visual color determination. Furthermore, perceptual aspects like perceptible or acceptable color differences are often not considered.

Purpose

The purpose of this study was to investigate the precision of a spectrophotometer in tooth shade determination compared with visual color matching using a shade guide in vitro. Moreover, the influence of different illuminants as well as of sex and professional experience of the examiners on visual color matching was analyzed.

Material and methods

Fifty examiners (13 men, 37 women; without dyschromatopsia), grouped by professional experience, determined the shades of 10 prosthetic teeth with the Vitapan classical shade guide under 4 illuminants (daylight, halogen, fluorescent [5000 K], fluorescent [nonspecific ceiling light]) and with a spectrophotometer (Shadepilot). Reproducibility (precision) of color determination was characterized by the average of the highest percentages of interexaminer agreement for each specimen. Additionally, color differences (ΔE) were calculated based on CIELab values.

Results

The mean reproducibility of the spectrophotometer was 92.2%, while for visual examination it was 43.7%. The corresponding differences in CIELab color space amounted to ΔEinstr=2.6 and ΔEvis=5.2. Illuminants and professional experience showed a significant influence, while sex did not.

Conclusion

While the spectrophotometer provided higher reproducibility, considering the color differences, the results obtained by visual inspection were still satisfactory. The differences due to type of illuminant, degree of experience, and sex of the examiners are of little practical relevance.

Section snippets

Material and Methods

Fifty examiners (37 women and 13 men, aged between 23 and 48 years) were recruited and their informed consent was obtained. They were divided in 2 groups with respect to experience. The first group (17) consisted of 5 dentists, 4 dental technicians, and 8 dental assistants with clinical shade matching experience. Twenty-nine dental students and 4 physicists were part of the second group (33) without experience. All participants were tested with the Ishihara color vision test to rule out

Results

The hit rates of the investigators were evaluated for the 4 illuminants. As seen in Figure 1, the halogen chair light had on average the lowest hit rate with 16.1%. The mean hit rate with daylight was 18.6%, with nonspecific fluorescent ceiling light, 18.8%, and with the fluorescent daylight lamp (5000 K), 18.1%.

Figure 2 shows that the median values of the hit rates differed more than the averages shown in Figure 1. The nonspecific fluorescent showed the widest spread with 45%. A Kruskal-Wallis

Discussion

In this study, 50 raters participated. The groups (inexperienced/experienced, men/women) were not of the same size. While the number of examiners corresponded to that in some other studies,10, 21 often there were only 2 or 3 examiners.6, 7, 8, 9, 12, 13, 14 The large spreads of hit rates and of ΔE values in visual examination (Fig. 2, Figure 4, Figure 5, Figure 6) indicate that judgments of color differences tend toward individual fluctuations. Thus, small numbers of examiners might be critical.

Conclusions

Color determination with the spectrophotometer investigated here generally led to better results compared with visual examination. One of the advantages of electro-optical examination is that it is not influenced by individual misjudgment. It provided a high reproducibility (92.2%) and can assist the visual examination, as well as replace it. While the comparatively low mean reproducibility of 43.7% and the low average hit rate of approximately 18% seem to indicate a significant disadvantage of

References (30)

  • R.D. Douglas et al.

    Intraoral determination of the tolerance of dentists for perceptibility and acceptability of shade mismatch

    J Prosthet Dent

    (2007)
  • G. Khashayar et al.

    Perceptibility and acceptability thresholds for colour differences in dentistry

    J Dent

    (2014)
  • R. Ghinea et al.

    Color difference thresholds in dental ceramics

    J Dent

    (2010)
  • H. Dagg et al.

    The influence of some different factors on the accuracy of shade selection

    J Oral Rehabil

    (2004)
  • S. Paul et al.

    Visual and spectrophotometric shade analysis of human teeth

    J Dent Res

    (2002)
  • Cited by (22)

    • Effects of conventional and heated tobacco product smoking on discoloration of artificial denture teeth

      2022, Journal of Prosthetic Dentistry
      Citation Excerpt :

      This device was not used under different illuminations because it has an integrated standardized illumination and is designed to ensure minimal influence of ambient light on data acquisition. The mean reproducibility of the spectrophotometer was approximately 92%.24 The specimens were placed on a standard black cardboard background.

    • Repeatability of the human eye compared to an intraoral scanner in dental shade matching

      2019, Heliyon
      Citation Excerpt :

      Clinical experience, in theory, should affect the ability of the observers to choose a dental tone, because with practice and repetition observers would be expected to develop protocols allowing more precise and reproducible results over time. However, despite the vast literature supporting this hypothesis [6, 21, 22, 23], many other studies have refuted it [8, 24, 25, 26]. Our results also refute this hypothesis, because while repeatability increased with experience from fourth-year students to fifth year students to prosthodontists, the differences were minimal and not statistically significant.

    • Influence of tongue position on the determination of tooth shade

      2017, Journal of Prosthetic Dentistry
      Citation Excerpt :

      Nevertheless, in clinical dental practice, subjective visual color determination is still frequently practiced2 and requires a continuous comparison with the reference tooth. As the literature suggests, environmental parameters have a substantial influence on the visually subjective determination of color,3,4 complicating adequate color determination. The reason for this is that natural teeth do not exhibit color homogeneity.18

    View all citing articles on Scopus
    View full text