Repeatability Of Visual, Spectrophotometer And Intraoral Scanner Methods In Shade Matching: A Comparative In-Vivo Study
Mohamed Fattouh1,4*, Laila M M Kenawi2,4, Omar A Aboelela3,4
1 Fixed Prosthodontics Department, Faculty of Dentistry, Cairo University, Cairo, Egypt.
2 Department of Endodontics, Faculty of Dentistry, Cairo University, Cairo, Egypt.
3 Lecturer, Crown and Bridge department, Faculty of Dentistry, Suez Canal University, Ismailia, Egypt.
4 Assistant Professor, Faculty of Dentistry, Umm Al-Qura University, Makkah, Saudi Arabia.
*Corresponding Author
Dr. Mohamed Fattouh,
Faculty of Dentistry, Umm Al-Qura University, P.O. Box 715, Makkah 24238, Saudi Arabia.
Tel: 00966592771003-00201005119793
Email Id: mohamed.fattouh@dentistry.cu.edu.eg
Received: April 17, 2021; Accepted: May 03, 2021; Published: May 11, 2021
Citation:Mohamed Fattouh, Laila M M Kenawi, Omar A Aboelela. Repeatability Of Visual, Spectrophotometer And Intraoral Scanner Methods In Shade Matching: A Comparative In-Vivo Study. Int J Dentistry Oral Sci. 2021;08(5):2439-2445. doi: dx.doi.org/10.19070/2377-8075-21000480
Copyright:Mohamed Fattouh©2021. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution and reproduction in any medium, provided the original author and source are credited.
Abstract
Introduction: Visual method of shade determination is highly subjective and a cause of concern for dentists. Instrumental
methods were used to determine tooth shade hoping to achieve superior esthetics. Great controversy still exist about the best
method and its repeatability for shade selection.
Objective: To compare and measure repeatability of three methods of shade determination, i.e.: visual, spectrophotometer,
and intraoral scanner methods by three groups with different experience level.
Materials and Methods: Fifty participantswith intact maxillary incisor teeth were selected. Thirty evaluators with different
experience level (6th year students, less than 2 years’ experience and prosthodontists) evaluated teeth shade.The shade of middle
third of right maxillary central incisors were recorded using visual, spectrophotometric and intraoral scanners methods.
Tooth color records (VITA 3D shade and L* a* b* values) were collected, the average repeatability of each evaluator and each
method were tabulated and subjected to suitable statistical analysis.
Results: Instrumental methods were more repeatable than visual methods. Intraoral scanner (Trios 3) recorded better repeatability(
94%) than VITA Easyshade Advance spectrophotometer (93%) but the difference was statistically non-significant.
when comparing the three methods, a statistically significant proportion of agreement between both [ visual and spectrophotometric
method (P < 0.01)] and [the visual and intraoral scanner method (P < 0.01)] with high percentage of agreements
“yes” .In the visual method, the prosthodontists records were more repeatable (84.16%)followed by dentist with less than 2
years’ experience (83.8%) then thestudents (81.5%), but the difference was not statistically significant.
Conclusion: Instrumental methods for shade selection using spectrophotometer or intraoral scanner were more repeatable
than the visual method. Trios3 intraoral scanner showed higher repeatability than Easy shade spectrophotometer. Visual shade
repeatability was influenced by the operator’s experience.
2.Introduction
3.Dermatoglyphics As A Diagnostic Tool In Syndromes
4.Dermatoglyphics As A Diagnostic Tool In Syndromes.
5.Conclusion
6.References
Keywords
Spectrophotometer; Intraoral Scanner; Easyshade Advance; Trios 3; Tooth Color; Shade Matching.
Introduction
Color selection of natural teeth is a Challenging step in fixed
prosthodontics as many restorations failed due to improper color
choice. Final shade of the restoration should match natural tooth
especially in the anterior region [1]. Shade determination can be
carried out by two methods: visual method with commercial shade
tabs or instrumental method by using a colorimeter, digital cameras,
spectrophotometer and recently by intraoral scanners [2-4].
There are three-color systems that provides the standard principles
for color analysis. Munsell color system involves a number of
colored chips for visual color matching, arranged in three dimensions
of appearance: (V: value), (H: hue), and (C: chroma). The
CIELAB color space (also famous as CIE L*a*b*) identifies color
as the following three values: L* for the lightness and it corresponds
to (Value) in Munsell system, a* from green (negative) to
red (positive), and b* for blue (negative) to yellow (positive) [5]. It
describes color properties freely from an established image. The
CIELAB color space is classically used when illustrations for print have to be changed from red green blue (RGB) to CMYK color
models [6]. The CIELCH is the third color space, the C* identifies
chroma and h° means hue angle for angular assessment. CIELCH
color system isrelated to physical samples established on Munsell
color scale [7]. CIE L*a*b* represents-according to Pecho et
al. [8] - the most accurate tool for color evaluation in dentistry.
The most popular method of shade determination is visual comparison
usingshade guide as Shofu Vintage shade guide, Ivoclar-
Vivadent Chromascop, Dentsply Portrait IPN shade guide, Vitapan
Classical, and VITA 3D-Master,however this method is
highly subjective and depends on multiple variables as age of the
dentist and his color perception, illumination,background, optical
illusion,intensity of light source and angle of incidence [9].VITA
3D-master shade guide is the most commonly used visual method,
considering the three parameters of color: hue, chroma, and
valueIt gives standardized and superior color selection [10]. In a
study carried by Pohlen et al. [11], VITA 3D-master shade guide
system recorded best shade matching results with more standard
color difference than other shade guides. VITA3D-master shade
guide has more ordered color distribution and higher color match
than other shade tabs. Electronic method significantly decreases
subjective errors of the visual shade guides. Electronic devices
that are used to determine teeth shade are ShadeScan (digital
camera with colorimeter, Cynovad, Canada), VITAEasyshade
(spectrophotometer, Vident, Brea, CA, USA), ShadeVision (digital
camera with colorimeter, X-Rite America, Inc., Grand Rapids,
Michigan, USA) and Spectroshade (spectrophotometer, MHT
Optic Research AG, Niederhasli, Switzerland) [4]. VITA Easyshade
Advance 4.0 (VITA Zahnfabrik, Bad Säckingen, Germany)
is a contact spectrophotometer, its probe is held at 90° on labial
surface of the selected tooth [12]. It has a standardized built-in
illumination that isn’t affected by surrounding illumination , making
its readings unaffected by surrounding moreover, it measures
the light energy returned from the tooth at 25 nm intervals across
the visible spectrum [13]. Trios 3 Intraoral scanner (3Shape, Copenhagen,
Denmark) had been used to record colored images and
distinguish between soft and hard tissue structures [2] where, the
light is projected to the teeth and then reflected to internal sensor
and managed by the scanner software to generate an image
from the scanned parts [14], shade matching is carried by LED
light, high-definition camera , computer software and it is based
on VITA shade guide [15]. The evaluator’s experience may play an
important role in shade matching, Della Bona et al. [16] reported
significant relationship between visual and the instrumental methodswhen
the dentists were experienced. Others support this idea
in researches carried out in different circumstances [9, 17-19], but
Kröger et al. [20] stated that experience had minimal role and
of no practical importance in shade selection between different
groups with variable experiences. Other researches [21-23] supported
this conclusion, arguing that when using the VITA 3Dmaster
shade guide, dentist’s experience was not an effectiveelement
in the selection of teeth shade.
The aim of this in vivo study was to compare the color matching
of maxillarycentral incisor using visual method (VITA 3D-master
shade guide) and instrumental methods using VITA Easyshade
and Trios 3. The null hypothesis was that there would not be a significant
difference between the shade matching methods as well
as the three groups of evaluators.
Material and Methods
Sample size was calculated according to previous published studies
[11, 16, 24], fifty participants representing 80% power to detect
a difference between means and a = 0.05,to be able to detect
significant differencesin results, sample size was calculated using
power analysis software (G*Power). This study was performed in
Fixed Prosthodontics Department clinics of Faculty of Dentistry,
Umm Alqura University, Makkah, Saudi Arabia. The Research
Ethics Committee of Umm Alqura University approved the study
protocol (Approval number: HAPO-02-K-012-2021-04-660). A
written informed consent describing the treatment plan, photos’
publishing, and collection of results was signed by each participant.
Participants’ selection
Shade matching procedures were performed on50 participants ,
Inclusion criteria were: Age range from 20 to 35 years with intact
maxillary incisor teeth with no history of endodontic treatment ,
any conservative or prosthetic restorations and with healthy periodontal
tissue, The exclusion criteria are 1) having teeth that have
been bleachedbefore 2) usage of medication 3) Presence of a systemic
disease 4) a history of taking antibiotics during childhood
or fever disease.
Evaluators’ classification
Evaluators of tooth shadewereclassified into three groups according
to their experience level. The first group (10 evaluators)
involved 6th year dental students from Faculty of Dentistry, Umm
Alqura University, the second group (10 evaluators) involved
dentist with less than two years (<2) of experience and the third
group involved 10 prosthodontists. All evaluators were checked
for any color vision impairments using the Ishihara color vision
test [25]. Evaluators with any kind of visual deficiency were excluded
from the study. They were trained on the proper usage of
the VITA3D-master shade guide , VITA Easy shade and Trios 3
according to the shade guide's and machine’s instruction manuals.
Shade matching procedures
The tooth selected for shade matching was the maxillary right
central incisor. After cleaning and polishing the teeth, shade recordings
were done for middle third of maxillary right central
incisor using three different methods: 1- Visual evaluation using
VITA 3D-master shade guide, 2- Spectrophotometric evaluation
using VITA Easyshade Advance, 3- intraoral scanner evaluation
using Trios 3 intraoral scanner. Matching procedureswas done
between 11:00 AM and 1.00 PM [26] with dental chair directed
toward North and facing sunlight. Each participant sit in upright
position at the same level from the evaluator’s eyes,40 cm. away
from the evaluator, with elimination of all bright colors as (lipstick,
tinted eye glasses).In between every measurement, each
evaluator re-adapted his eye by looking at a blue paper for five
seconds to prevent eye fatigue [27].
Visual shade selection
The VITA 3D-Master shade guide (VITA Zahnfabrik, Bad Säckingen,
Germany) was used for the visual shade selection method
(Figure 1). It uses the accepted color perception concepts of hue,
value and chroma where the first number represent value (light ness) then the letter represents hue and final number denotes
chroma. For every participant, the suitable shade was selected
based on the matching tab.
Spectrophotometer shade selection
A Clinical Spectrophotometer (VITA Easyshade Advance, VITA
Zahnfabrik, BadSäckingen, Germany) was used (Figure 2). The
manufacturer’s instructions were followed for shade recordings
wherethe Instrument probe tip was positioned on the middle third
of the upper right central incisor. The “Tooth single”program
was chosen for recording the shade and the L* a* b* values of
the tooth.
Intraoral Scanner shade selection
An intraoral scanner (Trios 3, 3Shape, Copenhagen, Denmark)
was used to scan maxillary right incisor from the incisal, vestibular
and palatal aspects,when the arch image was showed on the
screen, the “shade icon” wasapplied to the labial third of the
toothto determine theshade.
VITA Easyshade Advance and Trios 3 were calibrated before
scanning each tooth.The 3D-Master reference recorded by the
three methods was transformed into L*, a* and b* values using
the table assumed by Alshiddi et al. [17].
Data collection and statistical analysis
Collected data from the three methods were recorded. The average
repeatability and standard deviation (SD) of each evaluator
and each method were tabulated in Microsoft Excel sheet, each
dimension was considered individually. For the statistical analysis,
Statistical Package for the Social Sciences (SPSS version 22.0,
IBM Corporation, New York, USA) was used to analyze the repeatability
of each method. To analyze the repeatability of each
shade recording method, Analysis of variance (ANOVA) test was
carried out. Also, ANOVA test was used to evaluate the statistical
significance difference of the evaluator groups and to evaluate
which group of evaluator fulfilled a higher repeatability.Agreement
coefficient was tested between visual and spectrophotometric
methods using Cohen’s Kappa test. Agreement between visual
and spectrophotometric methods as well as between visual and
intraoral scanner methods was tested using z-test for proportions.
In all tests, (P < 0.05) was considered to be statistically significant.
Result
Tooth color records (VITA 3D shade and L* a* b* values) were
collected by the mean visual, spectrophotometer and intraoral
scanner methods (Table 1). Assessment of the repeatability of
shade matching using spectrophotometer and the intraoral scanner method was done and compared to the visual method. Repeatability
was evaluated by recognizing repeated measures from the
same participant . As shown in Figure 3,The visual method carried
by the sixth year dental students recorded the lowest repeatability
in shade matching with matching observations of 81.5%
and (SD=11.48%), followed by visual method by dentist with
less than two years’ experience (83.8%- SD=7.02%) then visual
method by prosthodontist (84.16%- SD=5.31%) then, spectrophotometer
(93%- SD=4.02%), while the intraoral scanner gave
the highest repeatability with 94% and SD= 4.6%.
There is statistical significant difference between Visual, spectrophotometer
methods as well as between Visual, intraoral scanner
methods (P = 0.003, P = 0.002 respectively). There is no statistical
significant differences between spectrophotometer and intraoral
scanner methods (P = 0.64).
The coefficient of agreement (using Kappa coefficient) was used
to compare of shades recorded by visual and spectrophotometric
systems, Results showed that (Kappa coefficient = 0.214) indicating
a fair agreement between the shades as done by these two
methods [Table 2]. Z test for proportions was used to compare
agreement between the visual and spectrophotometric method.
Results showed high proportion of agreement “yes” and there
was a statistically significant difference [ Z score was –4.1 and
P value was 0.00245 (P < 0.01)] (Table 3).Z test for proportions
was used to compare the agreement between visual and intraoral
scanner methods,results were statistically significant with high
proportion of agreement “yes” [the Zscore was -2.9and P =
0.00651(P < 0.01).](Table 4).The repeatability of visual shade
matching as influenced by evaluator’s experience was shown in
(Figure 3), ANOVA test showed that the differences between the
three groups were not statistically significant (P = 0.526).
Discussion
The science of color is acombination of science and art.Visual
matching using a shade guide is the most commonused method
to record the teeth shade. It depends on the evaluator’s visual
perception. This method is easy and economicalthat compares
teeth shade with a standard shade guide [28]. However, itdepends
on many psychological and physiological factors and can vary according
to surrounding environment [16, 17, 29]. An alternative
method of shade recording is using instrumental color measurements
as colorimeters, digital cameras, spectrophotometers and
intraoral scanners [30]. As the teeth color are greatly influenced
by the patient’s age so, participant’s age in this study was between
20 and 35 years [31].
Shade matching was taken in the middle third of the tooth because
the incisal third usually shows some translucent areas or white
spots, this may give a mixed colors that are difficult to be recorded
by spectrophotometers [32] Also, the cervical third shade may
change due to contrast of the gingiva.VITAEasyshadeintraoral
spectrophotometer was used in this study, its probe is positioned
on the tooth giving precise measurement in the form of L* a* b*
values. Trios 3 intraoral scanner has confocal microscopy with 20
microns accuracy; it uses photo-imaging technique to scan the
tooth [33]. There is great controversy regarding the repeatability
of visual and instrumental methods. The null hypothesis that the tested methods for shade recording would have similar repeatability
and that no alteration would be between their deviation
records was rejected. The null hypothesis was rejected as shade
matching using spectrophotometer or intraoral scanner was more
repeatable than visual method, this was previously confirmed
in other studies [4, 11, 12, 34-38]. Instrumental methods gave
more accurate results and facilitating communication between
dental professionals [39, [40]. Some studies showed that visual
matching is more reliable than instrumental one [41, 42], Bahannan
[21] reported that VITA Easy shade gave 80.4% of correct
shade matches while visual shade guide records 36.3% of shade
matches. Moreover, shade matching by Easyshade was more repeatable
than the VITA classical shade guide was. Jarad et al. [43]
investigated computer-based shade determination and found that
it improves the dentist’s capability to match the shade in a tough
situation when it is difficult to assess a single tab to match the
tooth, matching was 61.1% with computer while it was 41% in
conventional method. Some studies recommended using both
visual and instrumental methods to integrate each other achieving
superior results [44, 45] but, the high price of these machines limits
its spread in clinical practice [46].Our result wasreflected on the
percentage of agreement of shade selection between the visual
and bothinstrumental methods (Tables 3 and 4). The percentage
of agreement between visual and spectrophotometric method
was 72%, between visual and intraoral scanner method was 68%,
whichare statistically significant. Gómez-Polo et al. [47] showed a
significant differences between visual method and spectrophotometricone,
they found a high “ value” agreement when compared
to “chroma andhue”. No significant differences in repeatability
was found between VITA Easyshade spectrophotometer and Trios
3 intraoral scanner. Previous studies proved the same result
where Easy shade accuracy where comparable to trios even in
clinical situations [48, 49].
Yilmaz et al.[28] proved that no significant difference between
instrumental and visual matching when carried out by an expert
dentist. Theoretically, dentist’s experience should affect shade
determination because dental practice and repetition will allows
reproducible and more accurate results over time. Many studies
support this hypothesis [9, 16, 18, 50]. However, other researches
disprove it [20-23]. Our results also disagree with this rule, despite
there is increase in repeatability percent from sixth year dental
students to dentists with less than two years’ experience to experienced
prosthodontists, these differences were small with no
statistically significant.
Study limitations
No time limit for each shade-matching session, which may lead to
eye fatigue in visual method. No typical scanning technique has
been recommended for shade matching using intraoral scanners,
where factors as distance, scan angle and light source may affect
results.
Conclusion and Clinical Significance
Within the limitations of this clinical study, the following conclusions
were drawn:
1. Instrumental methods for shade selection using spectrophotometer
or intraoral scannerwere more repeatable than the visual method.
2. Trios3 intraoral scanner showed higher repeatability than Easy
shade spectrophotometer, but the difference was statistically nonsignificant.
3. Visual shade repeatability was influenced by the operator’s experience
but with no statistical significance difference between studied groups.
Further studies on larger sample size with the use of digital cameras
available in the market for shade selection are recommended,
also measuring color difference (E) between different methods of
shade selection is important.
Declaration of patient consent
All participants have given their written consent for their photos
and other data to be published in the journal without identifying
their names.
Conflict of interest
No conflicts of interest and No funding was received for the research
that could have influenced its results.
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