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 Table of Contents  
ORIGINAL ARTICLE
Year : 2021  |  Volume : 5  |  Issue : 2  |  Page : 37-41

Assessment of shade matching using visual and instrumental methods: An In vivo study


Department of Conservative Dentistry & Endodontics, Annoor Dental College & Hospital, Muvattupuzha Kerala University of Health Sciences, Thrissur, Kerala, India

Date of Submission15-Jun-2021
Date of Acceptance20-Oct-2021
Date of Web Publication29-Dec-2021

Correspondence Address:
Dr. Jesmy K Antony
Choozhikunnel House, Pulluvazhy P O, Ernakulam DT - 683 541, Kerala
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/sidj.sidj_8_21

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  Abstract 

Aims: This study aimed to compare the shade selection of natural teeth using visual method, digital photographic method, spectrophotometric method, and using an intraoral scanning device.
Settings and Design: A study was conducted at the department of conservative dentistry and endodontics.
Subjects and Methods: Right maxillary central incisors of ten subjects without caries, defects, or any restorations were selected for the study. Shade selection was done from the middle third of the labial surface of the tooth. In visual method the shade selection was carried out by an experienced clinician and in digital photographic method by a technician with gray cards as background and software analysis the other methods were spectrophotometric method and using an intraoral scanning device.
Statistical Analysis Used: Statistical analysis was done using the nonparametric Kruskal–Wallis test. Post hoc was done using the Mann–Whitney U-test.
Results: When the shades selected using the four methods were compared, with spectrophotometric methods, statistically significant differences were found for visual and digital photographic methods.
Conclusions: Whenever possible, it is better to combine visual and instrumental methods so as to reduce the subjective errors that can happen while using the visual method alone. Among the instrumental methods, the less expensive digital photographic method can be opted for instead of the more sophisticated methods with chances of minimal errors.

Keywords: Digital photographic method, intraoral scanner, spectrophotometric method, visual method


How to cite this article:
Antony JK, George L, Mathew J. Assessment of shade matching using visual and instrumental methods: An In vivo study. Saint Int Dent J 2021;5:37-41

How to cite this URL:
Antony JK, George L, Mathew J. Assessment of shade matching using visual and instrumental methods: An In vivo study. Saint Int Dent J [serial online] 2021 [cited 2022 May 29];5:37-41. Available from: https://www.sidj.org/text.asp?2021/5/2/37/334159




  Introduction Top


Proper shade matching plays a crucial role in the success of esthetic dental restorations. Achieving close shade matching of artificial dentition with that of natural teeth is a complex task. Owing to the high clinical relevance of precise shade selection, a number of different visual and instrumental methods have been developed over the years. In the visual method, the shades of natural teeth are compared with different shade guides. The most widely used shade guide is VITA classical shade guide. However, this method is subjective which is influenced by different factors such as observer color perception, observer bias, ambient lighting, and the acceptance threshold mismatch.[1] Instrument-based color measurement systems were developed to overcome the imperfections and inconsistencies of traditional shade matching. Digital cameras represent the most basic approach to electronic shade matching. The digital image is taken with a predetermined neutral reference adjacent to the object. An image editing software is used to standardize and analyze the color information of the digital image based on the neutral reference, such as a piece of gray card.

Spectrophotometer is more sophisticated instrument, built to measure hue, value, chroma, and translucency. Advantages of this include the ability to analyze the principal components of a series of spectra and its ability to convert spectrophotometric measures to various color measures. The measurements obtained by the instruments are frequently keyed to dental shade guides and converted to shade tab equivalent.[2] The intraoral scanners originally designed to take digital impressions have an added tool for shade selection. This innovation is very beneficial as it combines several functions to a single digital instrument which helps to reduce the working time.[3] The aim of the present study was to compare the shade selection of natural teeth by four different methods namely visual method using VITA classical shade guide, digital photographic method with gray cards, spectrophotometric method, and intraoral scanning device.


  Subjects and Methods Top


The study protocol was approved by the Institutional Scientific/Research Committee (IRC/03/19). All participants received written information about the study and signed informed consent before being included in the study. Test subjects were of 20–35 years of age. Ten vital intact nonrestored right maxillary central incisors were selected to get the readings using four different methods in this study. The readings were taken from the middle third of the labial surface of the selected tooth. The devices used were the same for all the samples. Selection of shades was done using VITAPAN classical shade guide (A1-D4) (VITA Zahnfabrik H. Rauter GmbH and Co., KG, Germany). The shade selection was done in the following order:

  • Group 1 – Visual method by the clinician (n = 10)
  • Group 2 – Digital photographic method by the technician (n = 10)
  • Group 3 – Measurement using spectrophotometer (n = 10)
  • Group 4 – Measurement using the intraoral scanner (n = 10).


For visual method without any color correcting devices, the patients were asked to remove the lipsticks and cosmetics and they were informed not to use pronounced dress colors to avoid its influence while taking the readings. Readings were made by an expert female clinician (3 years of experience) in the treatment room with a northward directed window and illumination as close to daylight as possible. The readings were taken within 5–7 s to avoid fatigue of eyes. The examiner was blinded to the shade color selected.

In the digital photographic method, photographs were taken with gray cards [Figure 1] and the selected shade tabs, close to the teeth in question. Photographs were taken in the same treatment room without the effect of external natural daylight. The shooting distance was set at 15–20 cm. Nikon DSLR Camera d5400 was used to take the photographs. Software analysis was carried out using ADOBE Photoshop (R). The readings were made by a dental technician with 15 years of experience in ceramic science.
Figure 1: Grey cards

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For spectrophotometric shade selection, SpectroShade Micro Dental Spectrophotometer (MHT Optic Research) was used [Figure 2]. During the shade-matching session, the selected image details were displayed on the high-resolution liquid crystal display (LCD) screen on which the tooth surface was divided into incisor third, middle third, and cervical third. The readings from the middle third of labial surface were taken. Intraoral scanner used in this study was TRIOS® Color (3Shape, Holmens Kanal, Copenhagen, DK) [Figure 3]. The right maxillary incisors of all the subjects were scanned and from the shades that appeared on the computer screen, the middle third shade was taken for comparison. Statistical analysis was done using SPSS version 24.0.0.0 (windows Version 22.0 Chicago, IL, USA). The shades A1 to D4 were numbered from 1 to 16 and the qualitative analysis was done. Kruskal–Wallis test was used to study the difference between the shades selected by the four different methods. Post hoc was done using Mann–Whitney U-test.
Figure 2: Spectrophotometric analysis

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Figure 3: Intra oral scanner analysis

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  Results Top


From [Table 1] the mean rank obtained for the [Graph-1] visual method was 25.45, for the digital photographic method it was 23.00, for the between method 1 and 3, for the spectrophotometric method it was 13.80, and for the intraoral scanning method, it was 19.75. From [Table 2], the pairwise comparison shows statistical significance of visual method and digital photographic method with the spectrophotometric method.
Table 1: Kruskal–Wallis test

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Table 2: Pairwise comparison

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  Discussion Top


Over the years, different methods have been adopted to select the shade of natural teeth to produce an esthetically pleasing smile. Numerous shade guides were introduced to get the most accurate shade matching. It was found that for experienced clinicians, high inter-examiner agreement has been demonstrated for shade selection regardless of the type of shade guides used.[4] It has also been demonstrated that there was no significant difference in terms of the color match between the crowns fabricated with either of the two shade guides that is Vita classical and Vita 3D Master.[5] So for the ease of standardization, Vita classic shade guide was used in this study.

In case of visual shade selection, it has been observed in some studies that professional experience has no effect on visual shade selection.[6],[7] It was also found that there are observer-related variables such as gender as females achieved better shade matching than males.[7],[8] To obtain standardization in the shades selected using visual method, a female clinician with 3 years of experience was selected in this study. When CIELAB values were measured for the shade tabs of different shade guides, it was found that the values are influenced by different illuminants (Suk Cha et al.).[9] When natural tooth and shade tab matching was conducted under natural daylight using different illuminants, the shades selected were not the same and showed metameric influences and color differences.[10] To avoid the influence of different illuminants all the readings were made in the same treatment room with a northward directed window and illumination as close to daylight as possible.

Digital photographic method is a subjective method and the influence of illuminants and the external color cast are reduced by the use of gray cards which was used as the neutral reference point. The image editing software used in this study was ADOBE Photoshop (R). This technique is very effective as we can communicate with the technician regarding the needs of the patient as well as the treating clinician effectively. The digital photograph can be taken with any brand of digital statutory liquidity ratio camera and advantageously, makes it more economical and easy to use.[11] However, much literature is lacking regarding the effectiveness of this technique in selecting the shades for a restoration. In this study when the digital photographic method was compared with other methods, the difference with the spectrophotometric method was high but not statistically significant.

The instrumental method for shade matching using the spectrophotometer was used in this study for comparison. The instrument was calibrated to obtain the VITA classical values. In this study, the results obtained by the spectrophotometric method were having statistically significant difference with the visual method. The use of these contact-type instruments may fall into a shortcoming that the small (usually three mm) window of the devices may not capture reliably the exact color information of the whole tooth surface. It poses difficulties in correctly positioning the device over the tooth surface during the measuring procedure. The second shortcoming is the improper measurement of the curved translucent surfaces found on teeth using the contact type instruments as they are designed for flat surfaces. When measuring the repeatability in measuring the shades, the spectrophotometer was found to be more reliable.[8] However in our study, the values obtained were lower for spectrophotometric method, even though a significant difference was there only with a visual method. Hence a combined use of both visual and instrumental method has to be promoted rather than depending on a single method, especially while using the spectrophotometers.

The Trios intraoral Scanner is a new patient-friendly and high-performance solution for intraoral scanning. The Trios system works according to the principle of confocal microscopy with a fast scanning time.[12] In addition to the process of scanning, it has an additional tool for the assessment of shade. This direct in vivo scanning of the teeth with light-emitting diode light and inbuilt computer software calculates the best shade for the restoration and this shade can be directly transferred to the dental technician together with the digital impression of the tooth. It can be calibrated to provide values according to VITA classical and VITA 3D Master shade guide. In this study, the values of Vita classical are used to make the comparison. According to the study done by Brandt et al., the repeatability in measuring the shades is better for Trios intraoral scanner when compared to the visual method.[13] Furthermore, this device can be used alone without requiring additional conventional color-measurement methods. In this study, the shades selected were not significantly different from that of the other three methods. Hence, this can be considered as a better alternative for the spectrophotometer.


  Conclusion Top


Within the limitations of this study, it was concluded that the newly emerging digital photography technique and intraoral scanner were as accurate as the visual method for shade selection. As there is an increased demand of digital integration in everyday life, especially in this pandemic scenario, the digital photographic method has got a very important place, especially because of the ease of transferring and storing data with high accuracy. Whenever possible while doing the shade selection with the spectrophotometer, it will be judicious to use a combination of both visual and instrumental methods in shade selection.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Ragain JC. A review of color science in dentistry: Colorimetry and color space. J Dent Oral Disord Ther 2016;4:1-5.  Back to cited text no. 1
    
2.
Chu SJ, Trushkowsky RD, Paravina RD. Dental color matching instruments and systems. Review of clinical and research aspects. J Dent 2010;38 Suppl 2:e2-16.  Back to cited text no. 2
    
3.
Moussaoui H, El Mdaghri M, Gouma A, Bennani B. Accuracy, repeatability and reproducibility of digital intraoral scanner for shade selection: current status of the literature. Oral Health Dental Sci 2018;2:1-6.  Back to cited text no. 3
    
4.
Della Bona A, Barrett AA, Rosa V, Pinzetta C. Visual and instrumental agreement in dental shade selection: Three distinct observer populations and shade matching protocols. Dent Mater 2009;25:276-81.  Back to cited text no. 4
    
5.
Öngül D, Şermet B, Balkaya MC. Visual and instrumental evaluation of color match ability of 2 shade guides on a ceramic system. J Prosthet Dent 2012;108:9-14.  Back to cited text no. 5
    
6.
Yılmaz B, Irmak Ö, Yaman BC. Outcomes of visual tooth shade selection performed by operators with different experience. J Esthet Restor Dent 2019;31:500-7.  Back to cited text no. 6
    
7.
Haddad HJ, Jakstat HA, Arnetzl G, Borbely J, Vichi A, Dumfahrt H, et al. Does gender and experience influence shade matching quality? J Dent 2009;37 Suppl 1:e40-4.  Back to cited text no. 7
    
8.
Liberato WF, Barreto IC, Costa PP, de Almeida CC, Pimentel W, Tiossi R. A comparison between visual, intraoral scanner, and spectrophotometer shade matching: A clinical study. J Prosthet Dent 2019;121:271-5.  Back to cited text no. 8
    
9.
Cha HS, Lee YK. Difference in illuminant-dependent color changes of shade guide tabs by the shade designation relative to three illuminants. Am J Dent 2009;22:350-6.  Back to cited text no. 9
    
10.
Corcodel N, Helling S, Rammelsberg P, Hassel AJ. Metameric effect between natural teeth and the shade tabs of a shade guide. Eur J Oral Sci 2010;118:311-6.  Back to cited text no. 10
    
11.
Wee AG, Lindsey DT, Kuo S, Johnston WM. Color accuracy of commercial digital cameras for use in dentistry. Dent Mater 2006;22:553-9.  Back to cited text no. 11
    
12.
Logozzo S, Franceschini G, Kilpelä A, Caponi M, Governi L, Blois L. A comparative analysis of intraoral 3D digital scanners for restorative dentistry. Internet J Med Technol 2011;5:1-8.  Back to cited text no. 12
    
13.
Brandt J, Nelson S, Lauer HC, von Hehn U, Brandt S. In vivo study for tooth colour determination-Visual versus digital. Clin Oral Investig 2017;21:2863-71.  Back to cited text no. 13
    


    Figures

  [Figure 1], [Figure 2], [Figure 3]
 
 
    Tables

  [Table 1], [Table 2]



 

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Abstract
Introduction
Subjects and Methods
Results
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