Evaluating percent correct shade identification: A practical approach to intraoral scanner and shade device performance

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The research question addresses how much clinicians can trust the device-selected shade without visual verification. Materials and Methods Sixteen participants with natural, unrestored teeth were included. The teeth evaluated were tooth 21 (left maxillary central incisor), tooth 23 (left maxillary canine), and tooth 26 (first left maxillary molar). Tooth color was measured using four IOS devices and the Vita Easyshade V in three regions: incisal, middle, and cervical. The nearest 3D Master shade selected by each device was compared to the visual observer’s selection. The percent exact match, acceptable match (> 1.2, ≤ 2.7 ∆ E ab ), and mismatch type A (< 2.7, ≤ 5.4 ∆ E ab ) were calculated. Statistical analysis was performed using a chi-square test with a 95% confidence level. Results The overall clinical pass rate was highest for Carestream (78.2%), followed by Easyshade (63.5%), Primescan (51.2%), Trios (39.5%), and Medit (31.3%). Carestream also recorded the highest rate of mismatch type A (47.7%). Significant differences between devices were observed for all categories (p < 0.05). Conclusions Carestream demonstrated the highest overall clinical pass rate, while Medit exhibited the lowest. The study highlights the variability between devices in shade matching performance. Clinical Relevance This study highlights the importance of considering device performance when relying on IOS or spectrophotometers for shade selection without visual assessment, as the reliability can vary significantly across devices. Intraoral scanners shade matching color measurement shade guide reliability visual-instrumental agreement Figures Figure 1 Introduction Dental research is increasingly focused on evaluating the accuracy and precision of shade measurement devices [ 1 , 2 ], with recent attention given to intraoral scanners (IOS) [ 3 – 5 ]. These devices are becoming more essential in restorative dentistry, with claims that they can also accurately measure tooth shades [ 6 , 7 ]. In clinical dentistry, the terms accuracy and precision are often used interchangeably, though their meanings can differ from how they are understood in color science. For example, an impression is said to be accurate , while there may be discussions of marginal precision in relation to indirect restorations or tooth anatomy replication [ 8 ]. In these contexts, accuracy and precision often imply a high level of congruency between the desired outcome and what was achieved, leading to their frequent interchangeable use. However, in color science, these terms are strictly defined, which can lead to confusion in dental colorimetric research. Colorimetric uncertainty is separated between accuracy and precision. Colorimetric accuracy refers to the calculated color difference between the spectral reflectance factors of reference standards, such as a set of 12 ceramic tiles, and the corresponding measurements from a given test device [ 9 – 11 ]. Colorimetric precision on the other hand refers to how consistently a measuring device provides results [ 12 ]. It is assessed by calculating the average color differences between 30 recommended repeated measurements of the same reference standards under identical conditions while colorimetric reproducibility measures consistency when certain conditions, such as the operator or sample, are varied [ 13 , 14 ]. Performing proper assessments of accuracy and precision in the context of instrument profiling is not a trivial task [ 15 , 16 ] and may not even be feasible for many shade measurement devices used in dentistry. These devices often rely on a mix of measurement technologies combined with illumination geometries outside of those recommended by the Commission internationale de l'éclairage ( CIE), to facilitate easy operation and meet clinical requirements. Numerous studies have set out to investigate supposed device accuracy [ 17 ], often by designating a spectrophotometer, most commonly the Vita Easyshade, as the gold standard [ 18 – 21 ], assuming it measures the true colorimetric values. The computed color difference between a set of tooth-colored samples measured by a test device and the reference device is frequently misinterpreted as colorimetric accuracy when it would be more accurately described as inter-device agreement [ 22 ]. Other studies have aimed to count how often a test device's selected shade matched the visual shade selection by an experienced observer, reporting the results as accuracy [ 23 , 24 ]. However, this approach would be more appropriately termed percent matching shade identification . Nevertheless, evaluating the congruency between observer- and instrument-selected shades offers practical insights into how much clinicians can rely on established shade measurement devices and, increasingly, on IOS, especially when visual shade selection was not performed due to the demands of clinical practice. Therefore, the aim of this study was to evaluate the reliability of shade selection by four contemporary IOS and one spectrophotometer, comparing device performance against an expert visual observer. The primary objective was to assess the clinical reliability of each device in shade selection by gathering data on the clinical pass rate, indicating how much clinicians can depend on the device's shade selection in practice. The null hypothesis was that there is no difference in device performance. Materials and methods Study setting For this study, a proportional ethical review application was submitted and received approval from the local Ethics Committee of the Medical Faculty (Approval number: EK-Freiburg 21-1169). The study followed good clinical practice guidelines and adhered to the principles outlined in the Declaration of Helsinki. A total of 16 participants, male and female, all under the age of 35 and with natural, unrestored teeth, were included. The teeth evaluated in this study were tooth 21 (left maxillary central incisor), tooth 23 (left maxillary canine), and tooth 26 (first left maxillary molar). Participant data was collected anonymously to protect their privacy, and only the project management team had access to the full data sets, ensuring no direct patient identification. Study procedure The devices examined in this study, listed in Table 1 , include four contemporary IOS and the Vita Easyshade V. Table 1 Devices included in the study, consisting of four IOS and Vita Easyshade V, along with corresponding abbreviations for each device Device Name Manufacturer Location Abbreviation Primescan Dentsply Sirona Bensheim, Germany ‘Primescan’ Medit i700 Medit Seoul, South Korea ‘Medit’ CS3700 Carestream LLC Atlanta, USA ‘Carestream’ Trios 3 3Shape Copenhagen, Denmark ‘Trios’ Easyshade V Vita Zahnfabrik Bad Säckingen, Germany ‘Easyshade’ A single expert observer, trained in both dental technology and clinical dentistry, conducted the visual shade assessments. The observer utilized a 3D Master shade guide (LOT J017B027IO, VITA Zahnfabrik, Bad Säckingen, Germany) for visual shade selections in three regions: the incisal, middle, and cervical areas of the labial and buccal surfaces. During each assessment, the patient sat upright, facing the observer. The lighting environment was optimized for shade selection, with large north-facing windows providing natural light, supplemented by color-corrected ceiling lighting. Color measurement Color measurements were performed by the same, trained operator over several days. Easyshade was used to measure tooth color in the incisal, medial, and cervical areas of the labial and buccal surfaces. Each IOS employed the color measurement mode of its respective system software to obtain shade designations in approximately the same three regions. In both cases, 3D Master shade designations were selected and recorded. Each complete measurement sequence took less than two minutes. To minimize potential color changes from dehydration, patients were asked to rinse their mouths with room temperature water to rehydrate their teeth between measurements. The spectral data from Easyshade, covering 400 to 700 nm in 10 nm intervals, was processed using the manufacturer’s software (ES_Helper, version 1.0.11081.369, Vita Zahnfabrik, Germany) to convert measurements to CIELAB coordinates under Illuminant D65 and the CIE 1931 standard colorimetric observer [ 25 ]. The same process was applied to the 3D Master shade guide used for visual assessments to ensure consistent data. Intraoral scans were collected in formats compatible with MeshLab (version 2023.12), including OBJ files for Primescan and Medit, and PLY files for Carestream and Trios. Scans were 3D-rotated in MeshLab to capture labial/buccal views, ensuring that measurements were consistently taken in the same three regions for both the natural teeth and all shade tabs of the Vita 3D Master shade guide. A custom MATLAB (R2023b; MathWorks, Natick, MA, USA) routine was used to capture average sRGB values from tooth surfaces in each scan, which were converted to XYZ and CIELAB coordinates using MATLAB’s color toolbox. The resulting data included the average tooth color from Easyshade and each IOS, as well as the corresponding CIELAB values for the nearest shade guide match. Using the CIELAB values of the natural target tooth for each region and the nearest device-selected shade tab for the same regions, the extent of the discrepancy between the device’s selection and the visually selected shade was calculated in cases where the two differed. This resulted in a total of 315 CIELAB values for comparisons per device. Statistical evaluation Statistical data analyses were also performed using MATLAB, focusing on the percent correct shade identification in three categories: Exact Match, Acceptable Match, and Mismatch Type A. Exact Match refers to instances where the device selected the same shade as the visual observer, while Acceptable Match indicates a clinically acceptable color difference (> 1.2, ≤ 2.7 Δ E ab ), between the device-selected shade and the target tooth. Mismatch Type A represents cases where the color difference (< 2.7, ≤ 5.4 Δ E ab ) is moderately unacceptable but still within a range considered for clinical use. Chi-square analysis was conducted to evaluate the significance of differences across devices for each of these categories. A 95% confidence level ( p = 0.05) was used. Results Results for all three regions for all included teeth and per each device, showing exact match, acceptable match and mismatch type A are shown in Fig. 1 . In the incisal region, Easyshade achieved the highest Exact Match rate at 20.3%, followed by Medit at 19.0%, and Trios at 19.7%. Carestream recorded the highest rate for acceptable matches in this region at 13.71%, while Easyshade had 5.1%. For Mismatch Type A in the incisal region, Carestream led with 46.7%, followed by Easyshade at 38.1%. In the middle region, Easyshade also had the highest Exact Match rate at 19.4%, while Carestream had the highest percentage of acceptable matches at 22.5%. Carestream also exhibited the highest rate for Mismatch Type A at 33.0%. For the cervical region, Primescan achieved the highest Exact Match at 17.5%, while Carestream had the most acceptable matches at 21.0%. Carestream also led in Mismatch Type A in this region at 48.6%. Averaged results across all three regions for all included teeth and per each device, showing Exact Match, Acceptable Match, Mismatch Type A, and overall clinical pass rate for each device are shown in Table 2 . These results reflect the average across the three regions and three teeth per patient. Carestream achieved the highest clinical pass rate at 78.2%, followed by Easyshade with 63.5%, Primescan with 51.2%, Trios with 39.5%, and Medit with 31.3%. The Exact Match percentages ranged from 11.3% for Primescan to 22.1% for Trios. For the Acceptable Match rate, Carestream showed the highest percentage at 14.0%, while Medit had no acceptable matches. Mismatch type A was highest for Carestream at 47.7% and lowest for Medit at 10.7%. Differences in the clinical pass rate and across all categories for each device were statistically significant at the 95% confidence level (p = 0.05). Table 2 Percentages of exact matches, acceptable matches (> 1.2, ≤ 2.7 ∆ E ab ), and mismatches type A (< 2.7, ≤ 5.4 ∆ E ab ) for each device, averaged across the cervical, middle and incisal regions. Clinical pass rate represents the sum of these categories, indicating likelihood of clinically agreeable shade selection by device. Chi-square test with 95% confidence level ( p = 0.05) was used to evaluate statistical significance Device Exact match Acceptable match Mismatch Type A Clinical Pass Rate Carestream 16.6% 14.0% 47.7% 78.2% Easyshade 20.3% 5.1% 38.1% 63.5% Primescan 11.3% 12.3% 27.6% 51.2% Trios 22.1% 4.3% 13.2% 39.5% Medit 20.6% 0% 10.7% 31.3% χ² 12.04 58.65 123.66 97.18 p = 0.05 p < 0.0171 p < 0.000 p < 0.000 p < 0.0001 Discussion This study aimed to evaluate the shade selection capabilities of various IOS, and one shade measurement device commonly mentioned in clinical research, from a practical perspective, rather than through the often-misinterpreted notion of device accuracy . The chosen approach focused on percent correct shade identification , grouping results into three clinically relevant categories: when a device’s selected shade either matched the observer’s selection, offered a clinically acceptable match, or was at least a moderately unacceptable match (Type A). To gauge clinical relevance, these categories were combined into a single measure referred to as the clinical pass rate . Device performance differed significantly, as demonstrated by the chi-square test results across all categories. To interpret these findings, it is important to consider that traditionally in psychophysical studies designed to determine visual thresholds, a 50% cutoff is often used as a standard [ 26 ]. Applying this concept to the present study, devices with a clinical pass rate at or above 50% should therefore be considered more reliable for shade selection, than those falling below this mark. Carestream, with a clinical pass rate of 78.2%, clearly outperformed the other devices, positioning it as the most reliable option. It consistently provided clinically passable results, whether through exact matches or acceptable shade differences, supporting the manufacturer’s claims about the superiority of Carestream’s smart-shade matching function [ 27 ]. Easyshade, which achieved a 63.5% pass rate, also performed well. In contrast, both Primescan and Trios hovered near or below the 50% threshold, with Primescan just meeting the cutoff at 51.2%. This raises questions about the reliability of these devices when used without visual confirmation of shade selection. Medit, with a clinical pass rate of only 31.3%, demonstrated the lowest performance, indicating it may require alternative use strategies in clinical practice. The visual ranking used in this study is grounded in established visual thresholds for clinical dentistry [ 28 ]. However, in practice, the acceptance or rejection of clinical restorations often depends on situational factors that cannot be entirely accounted for by visual thresholds. For instance, a clinical study by Ballard et al. [ 29 ] found that 94% of patients were either satisfied or extremely satisfied with an aveage shade match of 6.5 ∆ E ab thus exceeding the upper limit for clinical missmatch type A notably. Taking such findings into account, the inclusion of the Mismatch Type A category as part of the clinical pass rate can be justified with confidence. As already mentioned, there is growing interest in the shade matching capabilities of IOS [ 1 , 3 – 5 ]. However, differences in methodologies across studies, along with confusion surrounding the terms accuracy and precision make it difficult to directly compare these results with those of the present study. This research employed a unique methodology aimed at providing insights that are practically relevant to the average dental practitioner, demonstrating that the shade selection abilities of certain IOS devices are comparable to, or even better than, those of a popular shade measurement device, and can therefore be reasonably trusted. A key limitation of this study is the inclusion of only one expert observer and that a larger sample size of around 20 expert observers would have provided more robust and reliable results. Despite this limitation, the results of the present study demonstrate that IOS devices can indeed be reliable for shade selection, effectively meeting the demands of daily clinical practice. Conclusions Within the limitations of this study, it can be concluded that IOS and traditional shade measurement devices show varying degrees of reliability for shade selection. The clinical pass rate, as used in this research, provides a practical metric for assessing device performance. Carestream exhibited the highest clinical pass rate followed by Easyshade, suggesting that these devices can be reasonably trusted in clinical practice. Other devices performed at or below the 50% mark, indicating that their use for shade selection should be considered more carefully. Declarations Conflict of Interests The authors declare that they have no known competing financial interests or personal relationships that could have influenced the work reported in this paper. Ethica Approaval This study was conducted according to the Declaration of Helsinki and was approved by the Ethics Committee of the Medical Faculty of Albert-Ludwigs University Freiburg (Approval number: EK-Freiburg 21-1169; approval date: 17.08.2021). Informed Consent All participants provided written informed consent prior to their participation in the study. Details that might disclose their identity were excluded. Funding Open access funding was provided by the University of Leeds. Author Contribution J.N. and K.T.W. conceived the ideas; J.N. and M.M. collected the data; S.H. and S.W. analyzed the data; S.H. led the writing; J.N., S.W., B.C.S. and K.T.W. revised and approved the manuscript; S.H., B.C.S and K.T.W. provided the resources; K.T.W. supervised the research. Acknowledgement We thank the participants of this study for their efforts and patience. We would also like to thank PD Dr. med. dent. Sebastian B. M. 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Cite Share Download PDF Status: Published Journal Publication published 02 Jan, 2025 Read the published version in Clinical Oral Investigations → Version 1 posted Editorial decision: Revision requested 24 Nov, 2024 Reviews received at journal 24 Nov, 2024 Reviews received at journal 18 Nov, 2024 Reviews received at journal 17 Nov, 2024 Reviewers agreed at journal 13 Nov, 2024 Reviewers agreed at journal 11 Nov, 2024 Reviewers agreed at journal 10 Nov, 2024 Reviewers invited by journal 10 Nov, 2024 Editor assigned by journal 03 Nov, 2024 Submission checks completed at journal 03 Nov, 2024 First submitted to journal 31 Oct, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-5367140","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":377564538,"identity":"1a3bdb61-8ecf-4f7d-ab7b-a3ed59fa3811","order_by":0,"name":"Sascha Hein","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAv0lEQVRIiWNgGAWjYFCCBAZmhgoLMAMMJIjTckaCVC2MbaRokW9Pf/i5cJ6EHD97+gOGHzUMiTMbCGgxOPPGWHrmNgljyZ43Bow9xxgSZxOyxUAih42Zd5tE4oYbOQwMvA0MifMIOmxG+jNm3jkS9ftvpD9g/EuMFoYbCWbMvA0SCQZAxAyyhbDDQH7hOSZhOOPMG4PDMsckjAl6HxxiPDU28vxAxsM3NTayMw4QdBkSOEBURI6CUTAKRsEoIAwAHmM7WcxV9UsAAAAASUVORK5CYII=","orcid":"","institution":"University of Leeds","correspondingAuthor":true,"prefix":"","firstName":"Sascha","middleName":"","lastName":"Hein","suffix":""},{"id":377564539,"identity":"2e95bdd9-6746-4d3e-b7cd-62b9cefb8717","order_by":1,"name":"Julian Nold","email":"","orcid":"","institution":"University of Freiburg","correspondingAuthor":false,"prefix":"","firstName":"Julian","middleName":"","lastName":"Nold","suffix":""},{"id":377564540,"identity":"9d012ac6-abef-4647-84e2-e12fdeb0cea2","order_by":2,"name":"Matthias Masannek","email":"","orcid":"","institution":"University of Freiburg","correspondingAuthor":false,"prefix":"","firstName":"Matthias","middleName":"","lastName":"Masannek","suffix":""},{"id":377564541,"identity":"8e886961-4027-443d-92c1-729b77264feb","order_by":3,"name":"Stephen Westland","email":"","orcid":"","institution":"University of Leeds","correspondingAuthor":false,"prefix":"","firstName":"Stephen","middleName":"","lastName":"Westland","suffix":""},{"id":377564542,"identity":"e491a241-987e-4583-8bdc-22a039779975","order_by":4,"name":"Benedikt C. Spies","email":"","orcid":"","institution":"University of Freiburg","correspondingAuthor":false,"prefix":"","firstName":"Benedikt","middleName":"C.","lastName":"Spies","suffix":""},{"id":377564543,"identity":"0c7208a7-a31f-4622-bbc3-3723775ad6ea","order_by":5,"name":"Karl Thomas Wrbas","email":"","orcid":"","institution":"University of Freiburg","correspondingAuthor":false,"prefix":"","firstName":"Karl","middleName":"Thomas","lastName":"Wrbas","suffix":""}],"badges":[],"createdAt":"2024-10-31 11:23:49","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5367140/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5367140/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s00784-024-06124-0","type":"published","date":"2025-01-02T15:57:23+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":70507253,"identity":"415c7aca-9031-4777-8182-cbc0d0dfc11a","added_by":"auto","created_at":"2024-12-03 23:51:39","extension":"jpeg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":396906,"visible":true,"origin":"","legend":"\u003cp\u003ePercentages for all devices across incisal, middle, and cervical regions, displaying results of exact matches, acceptable matches (\u0026gt;1.2, ≤ 2.7 ∆\u003cem\u003eE\u003c/em\u003e\u003csub\u003eab\u003c/sub\u003e), and Mismatch Type A (\u0026lt;2.7, ≤ 5.4 ∆\u003cem\u003eE\u003c/em\u003e\u003csub\u003eab\u003c/sub\u003e). Results are shown for each device: Easyshade, Primescan, Medit, Carestream, and Trios\u003cstrong\u003e\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-5367140/v1/25cf8f222ad5e114f7d9c679.jpeg"},{"id":73093510,"identity":"a3c21f8b-5d94-40b6-96d8-5aba5eff046b","added_by":"auto","created_at":"2025-01-06 16:21:03","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":808584,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5367140/v1/d888c688-3243-4024-bc10-a510fc2b4d6e.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Evaluating percent correct shade identification: A practical approach to intraoral scanner and shade device performance","fulltext":[{"header":"Introduction","content":"\u003cp\u003eDental research is increasingly focused on evaluating the accuracy and precision of shade measurement devices [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e], with recent attention given to intraoral scanners (IOS) [\u003cspan additionalcitationids=\"CR4\" citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. These devices are becoming more essential in restorative dentistry, with claims that they can also accurately measure tooth shades [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn clinical dentistry, the terms \u003cem\u003eaccuracy\u003c/em\u003e and \u003cem\u003eprecision\u003c/em\u003e are often used interchangeably, though their meanings can differ from how they are understood in color science. For example, an impression is said to be \u003cem\u003eaccurate\u003c/em\u003e, while there may be discussions of \u003cem\u003emarginal precision\u003c/em\u003e in relation to indirect restorations or tooth anatomy replication [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. In these contexts, \u003cem\u003eaccuracy\u003c/em\u003e and \u003cem\u003eprecision\u003c/em\u003e often imply a high level of congruency between the desired outcome and what was achieved, leading to their frequent interchangeable use.\u003c/p\u003e \u003cp\u003eHowever, in color science, these terms are strictly defined, which can lead to confusion in dental colorimetric research. Colorimetric uncertainty is separated between accuracy and precision. Colorimetric accuracy refers to the calculated color difference between the spectral reflectance factors of reference standards, such as a set of 12 ceramic tiles, and the corresponding measurements from a given test device [\u003cspan additionalcitationids=\"CR10\" citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Colorimetric precision on the other hand refers to how consistently a measuring device provides results [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. It is assessed by calculating the average color differences between 30 recommended repeated measurements of the same reference standards under identical conditions while colorimetric reproducibility measures consistency when certain conditions, such as the operator or sample, are varied [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e].\u003c/p\u003e \u003cp\u003ePerforming proper assessments of accuracy and precision in the context of instrument profiling is not a trivial task [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e] and may not even be feasible for many shade measurement devices used in dentistry. These devices often rely on a mix of measurement technologies combined with illumination geometries outside of those recommended by the \u003cem\u003eCommission internationale de l'\u0026eacute;clairage\u003c/em\u003e \u003cb\u003e(\u003c/b\u003eCIE), to facilitate easy operation and meet clinical requirements.\u003c/p\u003e \u003cp\u003eNumerous studies have set out to investigate \u003cem\u003esupposed\u003c/em\u003e device accuracy [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e], often by designating a spectrophotometer, most commonly the Vita Easyshade, as the \u003cem\u003egold standard\u003c/em\u003e [\u003cspan additionalcitationids=\"CR19 CR20\" citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e], assuming it measures the \u003cem\u003etrue\u003c/em\u003e colorimetric values. The computed color difference between a set of tooth-colored samples measured by a test device and the reference device is frequently misinterpreted as colorimetric accuracy when it would be more accurately described as \u003cem\u003einter-device agreement\u003c/em\u003e [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Other studies have aimed to count how often a test device's selected shade matched the visual shade selection by an experienced observer, reporting the results as \u003cem\u003eaccuracy\u003c/em\u003e [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. However, this approach would be more appropriately termed \u003cem\u003epercent matching shade identification\u003c/em\u003e.\u003c/p\u003e \u003cp\u003eNevertheless, evaluating the congruency between observer- and instrument-selected shades offers practical insights into how much clinicians can rely on established shade measurement devices and, increasingly, on IOS, especially when visual shade selection was not performed due to the demands of clinical practice.\u003c/p\u003e \u003cp\u003eTherefore, the aim of this study was to evaluate the reliability of shade selection by four contemporary IOS and one spectrophotometer, comparing device performance against an expert visual observer. The primary objective was to assess the clinical reliability of each device in shade selection by gathering data on the clinical pass rate, indicating how much clinicians can depend on the device's shade selection in practice. The null hypothesis was that there is no difference in device performance.\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy setting\u003c/h2\u003e \u003cp\u003e For this study, a proportional ethical review application was submitted and received approval from the local Ethics Committee of the Medical Faculty (Approval number: EK-Freiburg 21-1169). The study followed good clinical practice guidelines and adhered to the principles outlined in the Declaration of Helsinki. A total of 16 participants, male and female, all under the age of 35 and with natural, unrestored teeth, were included. The teeth evaluated in this study were tooth 21 (left maxillary central incisor), tooth 23 (left maxillary canine), and tooth 26 (first left maxillary molar). Participant data was collected anonymously to protect their privacy, and only the project management team had access to the full data sets, ensuring no direct patient identification.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eStudy procedure\u003c/h3\u003e\n\u003cp\u003eThe devices examined in this study, listed in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, include four contemporary IOS and the Vita Easyshade V.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eDevices included in the study, consisting of four IOS and Vita Easyshade V, along with corresponding abbreviations for each device\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDevice Name\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eManufacturer\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eLocation\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eAbbreviation\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePrimescan\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDentsply Sirona\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eBensheim, Germany\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026lsquo;Primescan\u0026rsquo;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMedit i700\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMedit\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSeoul, South Korea\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026lsquo;Medit\u0026rsquo;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCS3700\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCarestream LLC\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eAtlanta, USA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026lsquo;Carestream\u0026rsquo;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTrios 3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3Shape\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCopenhagen, Denmark\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026lsquo;Trios\u0026rsquo;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eEasyshade V\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eVita Zahnfabrik\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eBad S\u0026auml;ckingen, Germany\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026lsquo;Easyshade\u0026rsquo;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eA single expert observer, trained in both dental technology and clinical dentistry, conducted the visual shade assessments. The observer utilized a 3D Master shade guide (LOT J017B027IO, VITA Zahnfabrik, Bad S\u0026auml;ckingen, Germany) for visual shade selections in three regions: the incisal, middle, and cervical areas of the labial and buccal surfaces. During each assessment, the patient sat upright, facing the observer. The lighting environment was optimized for shade selection, with large north-facing windows providing natural light, supplemented by color-corrected ceiling lighting.\u003c/p\u003e\n\u003ch3\u003eColor measurement\u003c/h3\u003e\n\u003cp\u003eColor measurements were performed by the same, trained operator over several days. Easyshade was used to measure tooth color in the incisal, medial, and cervical areas of the labial and buccal surfaces. Each IOS employed the color measurement mode of its respective system software to obtain shade designations in approximately the same three regions. In both cases, 3D Master shade designations were selected and recorded. Each complete measurement sequence took less than two minutes. To minimize potential color changes from dehydration, patients were asked to rinse their mouths with room temperature water to rehydrate their teeth between measurements.\u003c/p\u003e \u003cp\u003eThe spectral data from Easyshade, covering 400 to 700 nm in 10 nm intervals, was processed using the manufacturer\u0026rsquo;s software (ES_Helper, version 1.0.11081.369, Vita Zahnfabrik, Germany) to convert measurements to CIELAB coordinates under Illuminant D65 and the CIE 1931 standard colorimetric observer [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. The same process was applied to the 3D Master shade guide used for visual assessments to ensure consistent data. Intraoral scans were collected in formats compatible with MeshLab (version 2023.12), including OBJ files for Primescan and Medit, and PLY files for Carestream and Trios. Scans were 3D-rotated in MeshLab to capture labial/buccal views, ensuring that measurements were consistently taken in the same three regions for both the natural teeth and all shade tabs of the Vita 3D Master shade guide. A custom MATLAB (R2023b; MathWorks, Natick, MA, USA) routine was used to capture average sRGB values from tooth surfaces in each scan, which were converted to XYZ and CIELAB coordinates using MATLAB\u0026rsquo;s color toolbox. The resulting data included the average tooth color from Easyshade and each IOS, as well as the corresponding CIELAB values for the nearest shade guide match.\u003c/p\u003e \u003cp\u003eUsing the CIELAB values of the natural target tooth for each region and the nearest device-selected shade tab for the same regions, the extent of the discrepancy between the device\u0026rsquo;s selection and the visually selected shade was calculated in cases where the two differed. This resulted in a total of 315 CIELAB values for comparisons per device.\u003c/p\u003e\n\u003ch3\u003eStatistical evaluation\u003c/h3\u003e\n\u003cp\u003eStatistical data analyses were also performed using MATLAB, focusing on the percent correct shade identification in three categories: Exact Match, Acceptable Match, and Mismatch Type A. Exact Match refers to instances where the device selected the same shade as the visual observer, while Acceptable Match indicates a clinically acceptable color difference (\u0026gt;\u0026thinsp;1.2, \u0026le; 2.7 Δ\u003cem\u003eE\u003c/em\u003e\u003csub\u003eab\u003c/sub\u003e), between the device-selected shade and the target tooth. Mismatch Type A represents cases where the color difference (\u0026lt;\u0026thinsp;2.7, \u0026le; 5.4 Δ\u003cem\u003eE\u003c/em\u003e\u003csub\u003eab\u003c/sub\u003e) is moderately unacceptable but still within a range considered for clinical use. Chi-square analysis was conducted to evaluate the significance of differences across devices for each of these categories. A 95% confidence level (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.05) was used.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eResults for all three regions for all included teeth and per each device, showing exact match, acceptable match and mismatch type A are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. In the incisal region, Easyshade achieved the highest Exact Match rate at 20.3%, followed by Medit at 19.0%, and Trios at 19.7%. Carestream recorded the highest rate for acceptable matches in this region at 13.71%, while Easyshade had 5.1%. For Mismatch Type A in the incisal region, Carestream led with 46.7%, followed by Easyshade at 38.1%. In the middle region, Easyshade also had the highest Exact Match rate at 19.4%, while Carestream had the highest percentage of acceptable matches at 22.5%. Carestream also exhibited the highest rate for Mismatch Type A at 33.0%. For the cervical region, Primescan achieved the highest Exact Match at 17.5%, while Carestream had the most acceptable matches at 21.0%. Carestream also led in Mismatch Type A in this region at 48.6%.\u003c/p\u003e \u003cp\u003eAveraged results across all three regions for all included teeth and per each device, showing Exact Match, Acceptable Match, Mismatch Type A, and overall clinical pass rate for each device are shown in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. These results reflect the average across the three regions and three teeth per patient. Carestream achieved the highest clinical pass rate at 78.2%, followed by Easyshade with 63.5%, Primescan with 51.2%, Trios with 39.5%, and Medit with 31.3%. The Exact Match percentages ranged from 11.3% for Primescan to 22.1% for Trios. For the Acceptable Match rate, Carestream showed the highest percentage at 14.0%, while Medit had no acceptable matches. Mismatch type A was highest for Carestream at 47.7% and lowest for Medit at 10.7%. Differences in the clinical pass rate and across all categories for each device were statistically significant at the 95% confidence level (p\u0026thinsp;=\u0026thinsp;0.05).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003ePercentages of exact matches, acceptable matches (\u0026gt;\u0026thinsp;1.2, \u0026le; 2.7 ∆\u003cem\u003eE\u003c/em\u003e\u003csub\u003eab\u003c/sub\u003e), and mismatches type A (\u0026lt;\u0026thinsp;2.7, \u0026le; 5.4 ∆\u003cem\u003eE\u003c/em\u003e\u003csub\u003eab\u003c/sub\u003e) for each device, averaged across the cervical, middle and incisal regions. Clinical pass rate represents the sum of these categories, indicating likelihood of clinically agreeable shade selection by device. Chi-square test with 95% confidence level (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.05) was used to evaluate statistical significance\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDevice\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eExact match\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eAcceptable match\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMismatch Type A\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eClinical Pass Rate\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCarestream\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e16.6%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e14.0%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e47.7%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e78.2%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eEasyshade\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e20.3%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5.1%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e38.1%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e63.5%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePrimescan\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e11.3%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e12.3%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e27.6%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e51.2%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTrios\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e22.1%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4.3%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e13.2%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e39.5%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMedit\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e20.6%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e10.7%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e31.3%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eχ\u0026sup2;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e12.04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e58.65\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e123.66\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e97.18\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.0171\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis study aimed to evaluate the shade selection capabilities of various IOS, and one shade measurement device commonly mentioned in clinical research, from a practical perspective, rather than through the often-misinterpreted notion of \u003cem\u003edevice accuracy\u003c/em\u003e. The chosen approach focused on \u003cem\u003epercent correct shade identification\u003c/em\u003e, grouping results into three clinically relevant categories: when a device\u0026rsquo;s selected shade either matched the observer\u0026rsquo;s selection, offered a clinically acceptable match, or was at least a moderately unacceptable match (Type A). To gauge clinical relevance, these categories were combined into a single measure referred to as the \u003cem\u003eclinical pass rate\u003c/em\u003e.\u003c/p\u003e \u003cp\u003eDevice performance differed significantly, as demonstrated by the chi-square test results across all categories. To interpret these findings, it is important to consider that traditionally in psychophysical studies designed to determine visual thresholds, a 50% cutoff is often used as a standard [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. Applying this concept to the present study, devices with a clinical pass rate at or above 50% should therefore be considered more reliable for shade selection, than those falling below this mark.\u003c/p\u003e \u003cp\u003eCarestream, with a clinical pass rate of 78.2%, clearly outperformed the other devices, positioning it as the most reliable option. It consistently provided clinically passable results, whether through exact matches or acceptable shade differences, supporting the manufacturer\u0026rsquo;s claims about the superiority of Carestream\u0026rsquo;s smart-shade matching function [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. Easyshade, which achieved a 63.5% pass rate, also performed well.\u003c/p\u003e \u003cp\u003eIn contrast, both Primescan and Trios hovered near or below the 50% threshold, with Primescan just meeting the cutoff at 51.2%. This raises questions about the reliability of these devices when used without visual confirmation of shade selection. Medit, with a clinical pass rate of only 31.3%, demonstrated the lowest performance, indicating it may require alternative use strategies in clinical practice.\u003c/p\u003e \u003cp\u003eThe visual ranking used in this study is grounded in established visual thresholds for clinical dentistry [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. However, in practice, the acceptance or rejection of clinical restorations often depends on situational factors that cannot be entirely accounted for by visual thresholds. For instance, a clinical study by Ballard et al. [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e] found that 94% of patients were either satisfied or extremely satisfied with an aveage shade match of 6.5 ∆\u003cem\u003eE\u003c/em\u003e\u003csub\u003eab\u003c/sub\u003e thus exceeding the upper limit for clinical missmatch type A notably. Taking such findings into account, the inclusion of the Mismatch Type A category as part of the clinical pass rate can be justified with confidence.\u003c/p\u003e \u003cp\u003eAs already mentioned, there is growing interest in the shade matching capabilities of IOS [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan additionalcitationids=\"CR4\" citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. However, differences in methodologies across studies, along with confusion surrounding the terms \u003cem\u003eaccuracy\u003c/em\u003e and \u003cem\u003eprecision\u003c/em\u003e make it difficult to directly compare these results with those of the present study. This research employed a unique methodology aimed at providing insights that are practically relevant to the average dental practitioner, demonstrating that the shade selection abilities of certain IOS devices are comparable to, or even better than, those of a popular shade measurement device, and can therefore be reasonably trusted.\u003c/p\u003e \u003cp\u003eA key limitation of this study is the inclusion of only one expert observer and that a larger sample size of around 20 expert observers would have provided more robust and reliable results.\u003c/p\u003e \u003cp\u003eDespite this limitation, the results of the present study demonstrate that IOS devices can indeed be reliable for shade selection, effectively meeting the demands of daily clinical practice.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eWithin the limitations of this study, it can be concluded that IOS and traditional shade measurement devices show varying degrees of reliability for shade selection. The clinical pass rate, as used in this research, provides a practical metric for assessing device performance. Carestream exhibited the highest clinical pass rate followed by Easyshade, suggesting that these devices can be reasonably trusted in clinical practice. Other devices performed at or below the 50% mark, indicating that their use for shade selection should be considered more carefully.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eConflict of Interests\u003c/h2\u003e \u003cp\u003eThe authors declare that they have no known competing financial interests or personal relationships that could have influenced the work reported in this paper.\u003c/p\u003e \u003c/p\u003e\u003cp\u003e \u003ch2\u003eEthica Approaval\u003c/h2\u003e \u003cp\u003e This study was conducted according to the Declaration of Helsinki and was approved by the Ethics Committee of the Medical Faculty of Albert-Ludwigs University Freiburg (Approval number: EK-Freiburg 21-1169; approval date: 17.08.2021).\u003c/p\u003e \u003c/p\u003e\u003cp\u003e \u003ch2\u003eInformed Consent\u003c/h2\u003e \u003cp\u003e All participants provided written informed consent prior to their participation in the study. Details that might disclose their identity were excluded.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e \u003cp\u003eOpen access funding was provided by the University of Leeds.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eJ.N. and K.T.W. conceived the ideas; J.N. and M.M. collected the data; S.H. and S.W. analyzed the data; S.H. led the writing; J.N., S.W., B.C.S. and K.T.W. revised and approved the manuscript; S.H., B.C.S and K.T.W. provided the resources; K.T.W. supervised the research.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eWe thank the participants of this study for their efforts and patience. We would also like to thank PD Dr. med. dent. Sebastian B. M. Patzelt, M.Sc. for kindly providing the Carestream CS3700 intra oral scanner used in this study.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eTabatabaian F, Beyabanaki E, Alirezaei P, Epakchi S (2021) Visual and digital tooth shade selection methods, related effective factors and conditions, and their accuracy and precision: A literature review. J Esthet Restor Dent 33:1084\u0026ndash;1104. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttp://doi.org/10.1111/jerd.12816\u003c/span\u003e\u003cspan address=\"10.1111/jerd.12816\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRashid F, Farook TH, Dudley J (2023) Digital Shade Matching in Dentistry: A Systematic Review. 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J Esthet Restor Dent 31:103\u0026ndash;112. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttp://doi.org/10.1111/jerd.12465\u003c/span\u003e\u003cspan address=\"10.1111/jerd.12465\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBallard E, Metz MJ, Harris BT, Metz CJ, Chou J-C, Morton D et al (2017) Satisfaction of dental students, faculty, and patients with tooth shade-matching using a spectrophotometer. J Dent Educ 81:545\u0026ndash;553. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttp://doi.org/10.21815/JDE.016.022\u003c/span\u003e\u003cspan address=\"10.21815/JDE.016.022\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"clinical-oral-investigations","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"cloi","sideBox":"Learn more about [Clinical Oral Investigations](http://link.springer.com/journal/784)","snPcode":"784","submissionUrl":"https://submission.nature.com/new-submission/784/3","title":"Clinical Oral Investigations","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Intraoral scanners, shade matching, color measurement, shade guide reliability, visual-instrumental agreement","lastPublishedDoi":"10.21203/rs.3.rs-5367140/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5367140/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e \u003cb\u003eObjectives\u003c/b\u003e The study aimed to assess the percent correct shade identification of four intraoral scanners (IOS) and a spectrophotometer, focusing on how reliably each device selects the correct tooth shade compared to a visual observer\u0026rsquo;s selection. The research question addresses how much clinicians can trust the device-selected shade without visual verification.\u003c/p\u003e \u003cp\u003e \u003cb\u003eMaterials and Methods\u003c/b\u003e Sixteen participants with natural, unrestored teeth were included. The teeth evaluated were tooth 21 (left maxillary central incisor), tooth 23 (left maxillary canine), and tooth 26 (first left maxillary molar). Tooth color was measured using four IOS devices and the Vita Easyshade V in three regions: incisal, middle, and cervical. The nearest 3D Master shade selected by each device was compared to the visual observer\u0026rsquo;s selection. The percent exact match, acceptable match (\u0026gt;\u0026thinsp;1.2, \u0026le; 2.7 ∆\u003cem\u003eE\u003c/em\u003e\u003csub\u003eab\u003c/sub\u003e), and mismatch type A (\u0026lt;\u0026thinsp;2.7, \u0026le; 5.4 ∆\u003cem\u003eE\u003c/em\u003e\u003csub\u003eab\u003c/sub\u003e) were calculated. Statistical analysis was performed using a chi-square test with a 95% confidence level.\u003c/p\u003e \u003cp\u003e \u003cb\u003eResults\u003c/b\u003e The overall clinical pass rate was highest for Carestream (78.2%), followed by Easyshade (63.5%), Primescan (51.2%), Trios (39.5%), and Medit (31.3%). Carestream also recorded the highest rate of mismatch type A (47.7%). Significant differences between devices were observed for all categories (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/p\u003e \u003cp\u003e \u003cb\u003eConclusions\u003c/b\u003e Carestream demonstrated the highest overall clinical pass rate, while Medit exhibited the lowest. The study highlights the variability between devices in shade matching performance.\u003c/p\u003e \u003cp\u003e \u003cb\u003eClinical Relevance\u003c/b\u003e This study highlights the importance of considering device performance when relying on IOS or spectrophotometers for shade selection without visual assessment, as the reliability can vary significantly across devices.\u003c/p\u003e","manuscriptTitle":"Evaluating percent correct shade identification: A practical approach to intraoral scanner and shade device performance","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-12-03 23:51:34","doi":"10.21203/rs.3.rs-5367140/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-11-25T00:28:40+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-11-24T16:30:58+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-11-18T16:08:45+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-11-18T03:16:36+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"205433416833913375298251254407717366781","date":"2024-11-13T08:39:58+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"102623139573731511766570029622192272939","date":"2024-11-11T05:50:51+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"100241460182668708600682619154871145366","date":"2024-11-11T01:38:41+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-11-11T00:22:38+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-11-04T04:58:27+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-11-04T04:54:30+00:00","index":"","fulltext":""},{"type":"submitted","content":"Clinical Oral Investigations","date":"2024-10-31T11:13:28+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"clinical-oral-investigations","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"cloi","sideBox":"Learn more about [Clinical Oral Investigations](http://link.springer.com/journal/784)","snPcode":"784","submissionUrl":"https://submission.nature.com/new-submission/784/3","title":"Clinical Oral Investigations","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"5d794dc9-7a42-426b-9e88-313658408707","owner":[],"postedDate":"December 3rd, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-01-06T16:05:07+00:00","versionOfRecord":{"articleIdentity":"rs-5367140","link":"https://doi.org/10.1007/s00784-024-06124-0","journal":{"identity":"clinical-oral-investigations","isVorOnly":false,"title":"Clinical Oral Investigations"},"publishedOn":"2025-01-02 15:57:23","publishedOnDateReadable":"January 2nd, 2025"},"versionCreatedAt":"2024-12-03 23:51:34","video":"","vorDoi":"10.1007/s00784-024-06124-0","vorDoiUrl":"https://doi.org/10.1007/s00784-024-06124-0","workflowStages":[]},"version":"v1","identity":"rs-5367140","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5367140","identity":"rs-5367140","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}