Evaluation der Reproduzierbarkeit und Vergleichbarkeit verschiedener Verfahren zur klinisch-visuellen Farbbestimmung und Fotospektralanalyse von Zähnen
by Bernd Ludwig van der Heyd
Date of Examination:2024-09-25
Date of issue:2024-08-28
Advisor:Dr. Adam Rödiger
Referee:Dr. Adam Rödiger
Referee:Dr. Dr. Philipp Kanzow
Persistent Address:
http://dx.doi.org/10.53846/goediss-10680
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Abstract
English
Summary Due to the increasing digitalization in dentistry and dental technology, a digital, detailed tooth shade analysis and a direct transfer to the production of dental restorations would be desirable. At present, however, most tooth shade determinations are still carried out visually. In the present study, the two most commonly used visual shade guides in Europe, VITA classical and VITA 3D-MASTER, for determining tooth shades and two intraoral digital spectrophotometers (Shadepilot, DeguDent, Hanau and Crystaleye, Olympus, Hamburg) were examined for the reproducibility of shade determination. The question was investigated as part of this in vivo study: "How accurate is the reproducibility and comparability of different methods for clinical-visual color determination and photospectral analysis of teeth?" To enable a comparison of the visual tooth shade determination with the digital method, the individual methods had to be examined separately. Since the visual shade determination was an individual, subjective shade perception and the measured digital shade determinations were the analysis of physical shade (L*a*b* values) data, the focus here was particularly on the fact that not only a statement could be made as to whether there was a match or not, but also to what extent the determined visual or digital shade samples matched or differed in the tooth shade range. A preliminary investigation was carried out to improve the comparability of the individual shade analysis methods. For this purpose, the most frequently visually selected shade sample of the two shade guides in the individual tooth segments was determined by means of visual shade determination and defined as the reference tooth shade. This analysis and all other examinations were carried out by three examiners using 40 test subjects on teeth 12 - 22, in the cervical (S3), body (S2) and incisal (S1) areas. A ranking was then created based on the shade distances (ΔE) between the analyzed tooth shades and the determined reference tooth shade, which made it possible to compare the digital values with the visual values. Since only natural tooth structure (no fillings or similar) was to be examined, 470 of the 480 possible tooth segments were color analyzed and included in the examination. First, each tooth segment of a test subject was analyzed with the two shade guides, followed by the digital analysis of the tooth segments of the examiners using the two color measurement systems. The examinations thus amounted to 2820 individual visual analyses and 5640 digital analyses, making a total of 8460 individual examinations. For the statistical evaluation, the tooth was defined as a statistical unit and the intra-class correlation coefficient (ICC) was used as a measure of agreement. For this purpose, the single-linkage method (clustering) was used for the visual and digital examinations, as only one analysis method was involved in each case; the average-linkage method (clustering) was used for the comparison of the visual and digital examinations, as two different methods of shade taking were compared. A high ICC value (close to 1) stands for a good match, a low value (close to 0) for a poor match, for which the classification according to Fleiss (1986) was also used for better subdivision, whereby an ICC value of less than 0.4 corresponded to no match, between 0.4 and 0.75 to a reasonable to good match and a value above 0.75 to a very good match. The question of whether reproducibility by different examiners is given in the visual shade determination using the two shade guide systems could be assessed as appropriate to good with an ICC value of 0.64 (64 %). With an ICC value of 0.65, the VITA classical shade guide had a 2% higher agreement than the VITA 3D-MASTER shade guide with an ICC value of 0.63. There was a difference in the visual reproducibility between the central and lateral upper incisors, which was greater with both shade guide systems on the central incisors than on the lateral incisors. A large difference of 18 % was found between teeth 11, 21 with ICC values of 0.72 and 0.54 reproducibility on 12, 22 with the VITA 3D-MASTER shade guide. The VITA classical shade guide had a smaller difference of 4.5 % with ICC values of 0.67 on teeth 11, 21 and 0.628 on 12, 22. There were also differences in the shade taking in the different tooth areas, in the tooth body area (S2) the tooth shade could be best reproduced by both shade guides, the VITA classical shade guide showed the highest reproducibility here with an ICC value of 0.752, this was the only visual analysis result in the single-linkage method (cluster), which showed very good reproducibility, the VITA 3D-MASTER showed a lower, but still good reproducibility with an ICC value of 0.661 in this respect. The reproducibility of both shade guides was lower in the tooth incisal area (S1), here the VITA 3D-MASTER had an ICC value of 0.657 and the VITA classical of 0.602, the lowest value was in the cervical area (S3). Here, the reproducibility of both shade guides was just under 60 %, but still in a range that could be rated as adequate to good in terms of consistency. The question of whether the reproducibility of two photospectral analysis devices using two digital shade guide systems is given by the individual handling of the three examiners during digital tooth shade determination could be assessed as very good by evaluating the measurements. It was noticeable here that the digital shade analysis systems examined in this study exhibited clinically acceptable repeatability (ICC values) for all segments (S1, S2, S3) of the teeth examined. Overall, there was a very good reproducibility of 88.6 % (ICC value 0.886) of the shade samples suggested by the systems using both devices. There was only a minimal difference of 0.6 % in the reproducibility of the devices between the Shadepilot with an ICC value of 0.889 and the Crystaleye color measurement system with an ICC value of 0.883. The comparison of the two digitally stored shade guides using both measuring devices was almost identical except for a difference of 0.9 % and can be rated as very good, with the better reproducibility of the VITA classical shade guide (ICC values VITA classical 0.8905, VITA 3D-MASTER 0.8815). Similarly, in the digital comparison of the central (ICC value 0.891) and lateral incisors (ICC value 0.881), only a very slight difference of 1 % was measurable, with the better reproducibility of the central upper incisors. Similarly, there was hardly any difference between the colorimeters on the central and lateral incisors, with both systems showing very good agreement. The Shadepilot system had a slightly larger difference of 2.65% between the central and lateral incisors, while the Crystaleye shade measurement system only showed a difference of 1.85%, both systems with better reproducibility on the central incisors. In the tooth body area (S2), the tooth shade could be analyzed most reproducibly with very high ICC values of 0.924 using both shade tabs and shade guides together. The analyses in the tooth incisal area (S1) with an ICC value of 0.9173 were almost identical to the body area (S2). The reproducibility of the tooth neck (S3) with 81.68 % was 10.72 % lower than that of the tooth body area (S2). Nevertheless, this ICC value (0.8168) was still in a very good range. When comparing the two shade measuring devices in the tooth segments, the Shadepilot measuring device (ICC value 0.932) showed a 2.95 % higher reproducibility in the incisal area (S1) compared to the Crystaleye (ICC value 0.9025), whereas in S2 there was only a difference of 0.3 % between the measuring devices. Overall, the measured values of both colorimeters were close together in the cutting edge (S1) and body area (S2). The measurement reproducibility of both systems was consistently above 90 %. As in the previous study, both measuring devices again showed poorer measured values in the cervical area (S3), which were approx. 10 % lower in terms of reproducibility, with a 0.85 % better agreement for the Crystaleye system. The comparison of the digitally stored shade guides in the three tooth segments also showed a very good match, whereby the VITA classical shade guide in S1 with an ICC value of 0.923 and in S2 of 0.942, had a 3.5 % higher reproducibility in S1 and a 1.5 % higher reproducibility in S2 than the VITA 3D-MASTER shade guide. In the cervical area (S3), the match values were worse overall, the VITA 3D-MASTER showed an ICC value of 0.828 in S3 and thus a 2.2 % higher ICC value compared to the VITA classical shade guide with 0.806. In the cervical area (S3), the ICC value of the VITA classical shade guide was even 13.6 % below the ICC value of the tooth body area (S2). The comparison of the overall reproducibility by the examiners of the two digital systems using the two digitally stored shade guides was significantly higher than in the visual tooth shade determination using both shade guides. Despite the lower agreement of the visual shade analysis results, both the visual analyses and the digital measurements showed very good reproducibility with regard to the ICC values (Fleiss 1986). With an ICC value of 0.957 (95.7 %) reproducibility, the digital color analysis of tooth shades was superior to the reproducibility of the visual analysis with an ICC value of 0.836 (83.6 %) on the basis of the color determination systems tested in this study. Each digital system individually also showed significantly higher ICC values in terms of reproducibility in tooth shade determination than the visual analyses using the two shade guide systems, individually and together.
Keywords: clinical-visual color determination; photospectral analysis of teeth; reproducibility and comparability of color determination of teeth
