journal of dentistry 42 (2014) 48–52
Available online at www.sciencedirect.com
ScienceDirect journal homepage: www.intl.elsevierhealth.com/journals/jden
Shade matching quality among dental students using visual and instrumental methods Salma A. Bahannan * Oral and Maxillofacial Rehabilitation Department, Faculty of Dentistry, King Abdulaziz University, Saudi Arabia
article info
abstract
Article history:
Objectives: Study aims were to compare shade matching quality between visual and
Received 15 March 2013
machine-aided shade selection among dental students and to evaluate the effect of
Received in revised form
experience and gender.
21 August 2013
Methods: A total of 204 undergraduates and interns participated. They were briefed about
Accepted 10 November 2013
colour matching using a visual method with a Vita-3D Master system and a spectrophotometer. Participants with colour vision deficiency were excluded. Six maxillary anterior teeth of a maxillary blue stone cast were replaced with six maxillary artificial teeth.
Keywords:
Participants selected the best shade match using each method. A daylight illuminator with
Colour
the GTI mini-matcher colour viewing system was used during the test. The results were
Shade
statistically analysed with SPSS version 19 with 95% confidence intervals. Frequencies and
Matching
Chi-square tests were used to analyse the data, at a = 0.05 and with P < 0.05 indicating
Visual
significance.
Students
Results: Among the participants, 36.3% visually selected the correct shade, and 80.4% did so
Gender
using the Easy Shade Compact machine. Experience (P = 0.177) and gender (P = 0.560) did not affect visual shade selection; in addition, with the Easy Shade Compact device, males and females equally mastered its use (P = 1.0), and experience did not influence outcomes (P = 0.552). Conclusions: The shade matching device was significantly better than the conventional visual method. With both techniques, neither experience nor gender influenced shade matching quality. Clinical significance: Visual tooth colour matching is unreliable and inconsistent because of various subjective and objective factors, and the use of a colour measuring device might improve the quality of shade matching among dental students. # 2013 Elsevier Ltd. All rights reserved.
1.
Introduction
The success of aesthetic restorations depends primarily on the proper shade selection, and matching the correct tooth shade for anterior teeth is one of the most critical procedures. Many factors that contribute to the quality of shade matching have been mentioned in the literature and include receivers, tooth texture and contour, light source, the surroundings, and
background.1–7 Previous studies have noted differences among dentists concerning shade matching for the same teeth over days and among practitioners.8,9 Researchers have claimed that many variables such as colour deficiency, gender, experience, and eye fatigue can lead to inconsistencies and affect ability to select the proper shade.3,10–14 To eliminate the variability of conventional visual shade selection, electronic shade matching devices have been marketed. The devices are generally one of three types:
* Correspondence to: P.O. Box 10390, Jeddah 21433, Saudi Arabia. Tel.: +966 504 695 411; fax: +966 2 6952847. E-mail addresses: [email protected], [email protected]. 0300-5712/$ – see front matter # 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jdent.2013.11.001
journal of dentistry 42 (2014) 48–52
spectrophotometer, digital colour analyser, or colorimeter.1–15 These devices basically consist of a detector and signal conditioner and software that processes the signal to make the data usable in the clinic or laboratory.15 The selection of such an instrument depends on its reliability, accuracy, working life, and cost. A number of these electronic devices have been tested by evaluating their accuracy and precision or comparing results to visual observation.3–5,9,13,15–18 Yet, the subject remains controversial among researchers. Although one group concluded that the visual method (human examiners) was significantly better than that of the three digital devices tested,19 other groups have found that shade matching devices or digital cameras are more reliable and accurate.8,17,18 The purposes of this study were to compare the shade matching quality of visual matching and a shade selection device among dental students, and to evaluate the effect of the experience and gender on shade matching quality. The null hypothesis was that there would be no difference between methods and that gender and experience would have no effect on selecting the correct tooth shade.
2.
Materials and methods
2.1.
Subjects
A total of 204 volunteer students, all undergraduates and interns, participated in this study (102 men). The age range was 20–30 years with different levels of dental education (Table 1). The study was performed at the Faculty of Dentistry, King Abdulaziz University (KAU), in Jeddah, Saudi Arabia. It was approved by the Research Ethics Committee of the Faculty of Dentistry (REC-FD #019-11). All participants provided written consent before the study commenced. Two examiners did all procedures, helping each other. Participants were divided into two groups based on experience and education level. The first group consisted of third, fourth and fifth-year students who had little or no knowledge or experience regarding tooth shade matching. The second group had the knowledge and clinical experience with matching the tooth shade using the Vita- 3D Master Shade Guide System (Vita Zahnfabrik, Bad Sackingen, Germany). All participants underwent a Colour Vision Deficiency (CVD) test using Ishihara charts, which is a test for Colour-Blindness (Ishihara’s. Tokyo, Kanehara). CVD test was performed to each participant separately. Ishihara chart was held 75 cm from the participant and tilted so that the plane of the paper was perpendicular to the line of the vision. The participant read the Ishihara chart and the examiner compared it with the checklist provided with the booklet of the chart. A daylight
49
Fig. 1 – Maxillary cast with six maxillary artificial teeth.
illuminator with a GTI mini-matcher colour viewing system (GTI Graphic Technology, NY, USA) was used during the test. Participants with CVD were excluded.
2.2.
Shade matching
A maxillary blue stone cast (Whip Mix, Germany) was fabricated. The six maxillary stone anterior teeth were replaced with six maxillary artificial teeth (Vita Lumin Vacuum, Vita Zahnfabrik, Germany) (Fig. 1). The participants were given a presentation about how to do tooth shade matching using two techniques. The first one was a visual technique with the Vita-3D Master system (Vita Zahnfabrik, Germany), and the other one was the Easy Shade Compact device (Vita Zahnfabrik, Germany). The participants were asked to match one shade that of the maxillary right central incisor to avoid eye fatigue. Each participant selected the best shade match following the manufacturer’s instructions by selecting the value, chroma, and hue. The shade matching with the Vita-3D Master shade guide was done under the daylight illuminator (GTI Graphic Technology, NY, USA). The study was double blinded so that neither the examiners nor the participants knew the shade of the artificial teeth; only the principal investigator knew the correct shade. The Easy Shade Compact device was used according to the manufacturer’s instructions. It was calibrated after each participant’s usage. Since there is no contamination, the shield was not placed on the probe. The probe was touching the middle third of the tooth, and the shade tab mode was used for quality control.
2.3.
Statistical analysis
The results were analysed with SPSS version 19 and 95% confidence intervals. Frequencies and Chi-square tests were used to analyse the data, with a = 0.05 and significance set at P < 0.05.
3.
Results
Table 1 – Student class listing by frequency. Education level
Frequency Valid Percent
3rd Year
4th Year
5th Year
6th Year
Intern
Total
43 21.1
35 17.2
45 22.1
41 20.1
40 19.6
204
The overall ability for all students was low (36.3%) with the visual method (Table 2). There was not a statistical difference for experience in terms of ability to select the correct shade (P = 0.177). Table 3 also shows the lack of a significant gender difference in ability to visually select the correct matching shade (P = 0.560).
50
journal of dentistry 42 (2014) 48–52
Table 2 – Test correct by students class. P = 0.452. Types of shade matching
Groups Group 1 (3rd, 4th, 5th year)
Group 2 (6th Year, Intern)
41 (33.3%) 99 (80.5%)
33 (40.7%) 65 (80.2%)
Visual correct count (%) Easy shade correct count (%)
Total
P value
74 (36.3%) 164 (80.4%
0.0177% 0.552%
Table 3 – Test correct by gender. Types of shade matching
Gender
Visual correct count (%) Easy shade correct count (%)
Male
Female
35 (34.3%) 82 (80.4%)
39 (38.2%) 82 (80.4%)
Table 4 – Easy shade correct vs. test correct P = .098. Types of shade matching Easy shade? Yes count (%) No count (%) Total count (%)
Visual test correct
Total
Yes
No
64 (39.0%)
100 (61.0%)
164 (100.0%)
10 (25.0%) 74 (36.3%)
30 (75.0%) 130 (63.7%)
40 (100.0%) 204 (100.0%)
In contrast, 80.4% of participants (n = 164) gauged the correct shade using the Easy Shade Compact machine. Student experience had no significant influence (P < 0.552) (Table 2), and neither did gender (Table 3), as males and females equally mastered the use of the Easy Shade Compact device (P = 1.0). When the visual and Easy Shade methods were compared, 61.0% of those who could not match shades visually could do so with the Easy Shade (Table 4). Odds ratio (OR) analysis (Table 5) comparing the visual and Easy Shade methods revealed that students were 1.92 times less likely to match correctly using the visual method than to do so using the Easy Shade machine (OR = 1.92, 95% confidence interval, 0.879 to 4.194, P = 0.098).
4.
Discussion
About 30% of undergraduate students and interns at the Faculty of Dentistry at KAU participated in this study. All had
Table 5 – Odds ratio and relative risk. Easy shade correct vs. test correct. Value
Odds ratio for visual correct (correct/incorrect) For cohort easy shade correct = correct For cohort easy shade correct = incorrect No. of valid cases
95% confidence interval Lower
Upper
1.920
0.879
4.194
1.124
0.987
1.281
0.586
0.304
1.129
204
Total
P value
74 (36.3%) 164 (80.4%)
0.56 1.00
comparable age ranges and were divided into two groups based on education level. The Vita-3D Master Shade Guide System was chosen because it has resulted in higher colour match in studies comparing it with the Vitapan classical shade guide.11,20–22 It has been reported that Vita Classic shade guide tabs are not systematically distributed in the colour space relevant to human teeth, and that there is even overlap.23 Human visual colour assessments are a summation of physiological and psychological responses to a colour stimulus. The perception of colour by an observer is subjective, resulting in varied and unpredictable differences in colour evaluation and matching among clinicians.23,24 Researches reported that various factors such as the type and intensity of light source, angle of incidence, tooth texture and contour will complicate the shade taking procedure. However, participants with CVD were excluded here by use of the Ishihara test, one of the most commonly used screening tools for CVDs.11 This decision also took into account the results of Davison and Myslinski, who reported that colourdefective dental personnel make significantly greater errors in hue and chroma selection than normal-vision dental personnel.10 In this study, the shade matching for an artificial tooth with the conventional visual method differed significantly in percentage of correct matches (36.3%) compared with results for the Easy Shade Compact device (80.4%). With the visual technique, those 36.3% of participants chose the correct shade (value, chroma, and hue), but 22% had only the correct value and chroma. The participants found that this spectrophotometer was much easier to use than the conventional visual method. In addition, they did not have to worry about the light source, environment, or background. Our results are in agreement with others who have reported better results with spectrophotometer colour matching compared to visual shade assessment.17,25–28 Paul et al. suggested that spectrophotometric shade analysis is more accurate and more reproducible compared with human shade assessment.29 It has been mentioned that this approach can serve as a reliable addition in colour matching and enhances the level of shade analysis, communication, interpretation, and fabrication of dental restorations.30 Witkowski et al. reported that the accuracy and reproducibility of dental shade selection using a digital spectrophotometer with respect to examiner and illumination conditions reflected the reliability of the device.31
journal of dentistry 42 (2014) 48–52
In this study, the two groups organized by education level did not differ in their shade matching results. This finding is in agreement with those of previous groups13,27,28 that reported no effect on results of experience in shade matching. In contrast, however, Della Bona and colleagues reported that previous training in shade matching and clinical experience in dentistry played important roles in shade matching accuracy.32 In terms of gender, the traditional belief has been that women are more capable of matching colours than men,13 and other researchers have evaluated whether a difference exists between men and women in terms of shade matching ability.14,33–38 Haddad et al. found that females achieved significantly better shade matching results than males.13 Surprisingly, Miranda reported that men were more successful in discriminating shades.33 However, investigators in other studies have been unable to identify a significant influence of sex on shade matching ability.14,16,31,34,35 In agreement, our results showed that sex is not an important factor in shade matching and that male and female participants did not differ using either technique. Comparing the visual and Easy Shade methods, 61.0% of those who could not match shades visually for an artificial tooth could do so with Easy Shade. In addition, students were 1.92 times less likely to match correctly with the visual approach than to do so using the Easy Shade machine. The limitations of this study are that one shade was selected, but we were concerned about eye fatigue. To compensate for that limitation, the number of participants was increased. However artificial tooth was used to mimic the clinical situation.
5.
Conclusion
Within the limitations of this study, the shade matching device (Easy Shade Compact) was significantly better than the conventional visual method in yielding accurate results. Males and females did not differ significantly in outcomes with either technique, and experience had no significant influence on shade matching quality when selecting shade for artificial tooth.
Conflict of interest statement No conflict of interest is declared for this work.
Acknowledgments This Project was funded by Deanship of Scientific Research (DSR), King Abdulaziz University, Jeddah, under grant no. 1433/165/500. The author, therefore, acknowledge with thanks the technical and financial support. The author would like to express her sincere thanks to Professor Garnett Henley, Howard University College of Dentistry, USA, and Dr. Hanan Kadi in King abdulaziz University for their assistance in the statistical analysis. However she appreciates the help of Dr. Ghada Essa and Dr. Ghadi Muamenah in collecting the clinical data.
51
references
1. Sikri VK. Color implications in dentistry. Journal of Conservative Dentistry 2010;13:249–55. 2. Boksman L. Shade selection; accuracy and reproducibility. Ontario Dentist 2007:24–7. 3. Joiner A. Toothcolour: a review of the literature. Journal of Dentistry 2004;32:3–12. 4. Paravina RD. Evaluation of a newly developed visual shade matching apparatus. The International Journal of Prosthodontics 2002;15:528–34. 5. Stevenson B. Current methods of shade matching in dentistry: a review of the supporting literature. Dental Update 2009;36:274–6. 6. Johnston WM. Color measurement in dentistry. The International Journal of Prosthodontics 2009;37:2–6. 7. Dagg H, O’Connell B, Claffey N, Byrne D, Gorman C. The influence of some different factors on the accuracy of shade selection. Journal of Oral Rehabilitation 2004;31:900–4. 8. Horn D, Bulan-Brady J, Hicks M. Sphere spectrophotometer versus human evaluation of tooth shade. Journal of Endodontics 1998;24:786–90. 9. Jarad FD, Russell MD, Moss BW. The use of digital imaging for colour matching and communication in restorative dentistry. British Dental Journal 2005;199:43–9. 10. Davison SP, Myslinski NR. Shade selection by color visiondefective dental personnel. Journal of Prosthetic Dentistry 1990;63:97–101. 11. Vafaee F, Rakhshan V, Vafaei M, Khoshhal M. Accuracy of shade matching performed by colour blind and normal dental students using 3D Master and Vita Lumin shade guides. The European Journal of Prosthodontics and Restorative Dentistry 2012;20:23–5. 12. Cal E, Sonugelen M, Guneri P, Kesercioglu A, Kose T. Application of a digital technique in evaluating the reliability of shade guides. Journal of Oral Rehabilitation 2004;31:483–91. 13. Haddad HJ, Jakstat HA, Ametzl G, Borbely J, Vichi A, Dumfahrt H, et al. Does gender and experience influence shade matching quality. Journal of Dentistry 2009;37:e40–4. 14. Capa N, Malkondu O, Kazazoglu E, Calikkocaoglu S. Evaluating factors that affect the shade-matching ability of dentists, dental staff members and laypeople. Journal of the American Dental Association 2010;141:71–6. 15. Brewer JD, Wee A, Seghi R. Advances in color matching. Dental Clinics of North America 2004;48:341–58. 16. Chu SJ, Trushkowsky RD, Paravina RD. Dental color matching instruments and systems. Review of clinical and research aspects. Journal of Dentistry 2010;38:e2–16. 17. Paul S, Peter A, Pietrobon N, Hammerle CHF. Visual and spectrophotometric shade analysis of human teeth. Journal of Dental Research 2002;81:578–82. 18. Seghi RR, Johnston WM, O’Brien WJ. Spectrophotometric analysis of color differences between porcelain systems. Journal of Prosthetic Dentistry 1986;56:35–40. 19. Hugo B, Witzel T, Klaiber B. Comparison of in vivo visual and computer-aided tooth shade determination. Clinical Oral Investigation 2005;9:244–50. 20. Corciolani G, Vichi A, Goracci C, Ferrari M. Colour correspondence of a ceramic system in two different shade guides. Journal of Dentistry 2009;37:98–101. 21. Hassel AJ, Koke U, Schmitter M, Beck J, Rammelsberg P. Clinical effect of different shade guide systems on the tooth shades of ceramic veneered restorations. The International Journal of Prosthodontics 2005;18:422–6. 22. Dozic A, Kleverlaan CJ, Meegdes M, van der Zel J, Felizer AJ. The influence of porcelain layer thickness on the final shade
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journal of dentistry 42 (2014) 48–52
of ceramic restorations. Journal of Prosthetic Dentistry 2003;90:563–70. Dozic A, Kleverlaan CJ, Aartman IH, Felizer AJ. Relation in color of three regions vital human incisors. Dental Materials 2004;20:832–8. Bangtson LK, Goodkind RJ. The conversion of chromascan designations to CIE tristimulus values. Journal of Prosthetic Dentistry 1982;48:610–7. AlSaleh S, Labban M, AlHariri M, Tashkandi E. Evaluation of self shade matching ability of dental students using visual and instrumental means. Journal of Dentistry 2012;40:e82–7. Johnston WM. Color measurement in dentistry. Journal of Dentistry 2009;37:2–6. Cal E, Guneri P, Kose T. Comparison of digital and spectrophotometric measurements of colour shade guides. Journal of Oral Rehabilitation 2006;33:221–8. Gehrke P, Riekeberg U, Fackler O, Dhom G. Comparison of in vivo visual, spectrophotometric and colorimetric shade determination of teeth and implant-supported crowns. Journal of Esthetic and Restorative Dentistry 2010;22:53–65. Paul S, Peter A, Rodoni L, Pietrobon N. Conventional visual vs. spectrophotometric shade taking for porcelain-fused-tometal crowns: a clinical comparison. International Journal of Periodontics and Restorative Dentistry 2004;24:222–31. Macentee M, Lakowski R. Instrumental colour measurement of vital and extracted human teeth. Journal of Oral Rehabilitation 1981;8:203–8.
31. Witkowski S, Yajima ND, Wolkewitz M, Strub JR. Reliability of shade selection using an intraoral spectrophotometer. Clinical Oral Investigations 2012;16:945–9. 32. Della Bona A, Barrett AA, Rosa V, Visual Pinzetta C. instrumental agreement in dental shade selection: three distinct observer populations and shade matching protocols. Dental Materials 2009;25:276–81. 33. Miranda ME. Effect of gender, experience, and value on color perception. Operative Dentistry 2012;37:228–33. 34. Alomari M, Chadwick RG. Factors influencing the shade matching performance of dentists and dental technicians when using two different shade guides. British Dental Journal 2011;921:E23. 35. Poljak-Guberina R, Celebic A, Powers JM, Paravina RD. Colour discrimination of dental professionals and colour deficient laypersons. The European Journal of Prosthodontics and Restorative Dentistry 2011;39:e17–22. 36. McAndrew R, Chan PW, Milward PJ. An assessment of shade taking by dental undergraduates. The European Journal of Prosthodontics and Restorative Dentistry 2010;18:13–6. 37. Jasinevicius TR, Curd FM, Schilling L, Sadan A. Shadematching abilities of dental laboratory technicians using a commercial light source. Journal of Prosthodontics 2009;18:60–3. 38. Curd FM, Jasinevicius TR, Graves A, Cox V, Sadan A. Comparison of the shade matching ability of dental students using two light sources. Journal of Prosthetic Dentistry 2006;96:391–6.
Available online at www.sciencedirect.com
ScienceDirect journal homepage: www.intl.elsevierhealth.com/journals/jden
Shade matching quality among dental students using visual and instrumental methods Salma A. Bahannan * Oral and Maxillofacial Rehabilitation Department, Faculty of Dentistry, King Abdulaziz University, Saudi Arabia
article info
abstract
Article history:
Objectives: Study aims were to compare shade matching quality between visual and
Received 15 March 2013
machine-aided shade selection among dental students and to evaluate the effect of
Received in revised form
experience and gender.
21 August 2013
Methods: A total of 204 undergraduates and interns participated. They were briefed about
Accepted 10 November 2013
colour matching using a visual method with a Vita-3D Master system and a spectrophotometer. Participants with colour vision deficiency were excluded. Six maxillary anterior teeth of a maxillary blue stone cast were replaced with six maxillary artificial teeth.
Keywords:
Participants selected the best shade match using each method. A daylight illuminator with
Colour
the GTI mini-matcher colour viewing system was used during the test. The results were
Shade
statistically analysed with SPSS version 19 with 95% confidence intervals. Frequencies and
Matching
Chi-square tests were used to analyse the data, at a = 0.05 and with P < 0.05 indicating
Visual
significance.
Students
Results: Among the participants, 36.3% visually selected the correct shade, and 80.4% did so
Gender
using the Easy Shade Compact machine. Experience (P = 0.177) and gender (P = 0.560) did not affect visual shade selection; in addition, with the Easy Shade Compact device, males and females equally mastered its use (P = 1.0), and experience did not influence outcomes (P = 0.552). Conclusions: The shade matching device was significantly better than the conventional visual method. With both techniques, neither experience nor gender influenced shade matching quality. Clinical significance: Visual tooth colour matching is unreliable and inconsistent because of various subjective and objective factors, and the use of a colour measuring device might improve the quality of shade matching among dental students. # 2013 Elsevier Ltd. All rights reserved.
1.
Introduction
The success of aesthetic restorations depends primarily on the proper shade selection, and matching the correct tooth shade for anterior teeth is one of the most critical procedures. Many factors that contribute to the quality of shade matching have been mentioned in the literature and include receivers, tooth texture and contour, light source, the surroundings, and
background.1–7 Previous studies have noted differences among dentists concerning shade matching for the same teeth over days and among practitioners.8,9 Researchers have claimed that many variables such as colour deficiency, gender, experience, and eye fatigue can lead to inconsistencies and affect ability to select the proper shade.3,10–14 To eliminate the variability of conventional visual shade selection, electronic shade matching devices have been marketed. The devices are generally one of three types:
* Correspondence to: P.O. Box 10390, Jeddah 21433, Saudi Arabia. Tel.: +966 504 695 411; fax: +966 2 6952847. E-mail addresses: [email protected], [email protected]. 0300-5712/$ – see front matter # 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jdent.2013.11.001
journal of dentistry 42 (2014) 48–52
spectrophotometer, digital colour analyser, or colorimeter.1–15 These devices basically consist of a detector and signal conditioner and software that processes the signal to make the data usable in the clinic or laboratory.15 The selection of such an instrument depends on its reliability, accuracy, working life, and cost. A number of these electronic devices have been tested by evaluating their accuracy and precision or comparing results to visual observation.3–5,9,13,15–18 Yet, the subject remains controversial among researchers. Although one group concluded that the visual method (human examiners) was significantly better than that of the three digital devices tested,19 other groups have found that shade matching devices or digital cameras are more reliable and accurate.8,17,18 The purposes of this study were to compare the shade matching quality of visual matching and a shade selection device among dental students, and to evaluate the effect of the experience and gender on shade matching quality. The null hypothesis was that there would be no difference between methods and that gender and experience would have no effect on selecting the correct tooth shade.
2.
Materials and methods
2.1.
Subjects
A total of 204 volunteer students, all undergraduates and interns, participated in this study (102 men). The age range was 20–30 years with different levels of dental education (Table 1). The study was performed at the Faculty of Dentistry, King Abdulaziz University (KAU), in Jeddah, Saudi Arabia. It was approved by the Research Ethics Committee of the Faculty of Dentistry (REC-FD #019-11). All participants provided written consent before the study commenced. Two examiners did all procedures, helping each other. Participants were divided into two groups based on experience and education level. The first group consisted of third, fourth and fifth-year students who had little or no knowledge or experience regarding tooth shade matching. The second group had the knowledge and clinical experience with matching the tooth shade using the Vita- 3D Master Shade Guide System (Vita Zahnfabrik, Bad Sackingen, Germany). All participants underwent a Colour Vision Deficiency (CVD) test using Ishihara charts, which is a test for Colour-Blindness (Ishihara’s. Tokyo, Kanehara). CVD test was performed to each participant separately. Ishihara chart was held 75 cm from the participant and tilted so that the plane of the paper was perpendicular to the line of the vision. The participant read the Ishihara chart and the examiner compared it with the checklist provided with the booklet of the chart. A daylight
49
Fig. 1 – Maxillary cast with six maxillary artificial teeth.
illuminator with a GTI mini-matcher colour viewing system (GTI Graphic Technology, NY, USA) was used during the test. Participants with CVD were excluded.
2.2.
Shade matching
A maxillary blue stone cast (Whip Mix, Germany) was fabricated. The six maxillary stone anterior teeth were replaced with six maxillary artificial teeth (Vita Lumin Vacuum, Vita Zahnfabrik, Germany) (Fig. 1). The participants were given a presentation about how to do tooth shade matching using two techniques. The first one was a visual technique with the Vita-3D Master system (Vita Zahnfabrik, Germany), and the other one was the Easy Shade Compact device (Vita Zahnfabrik, Germany). The participants were asked to match one shade that of the maxillary right central incisor to avoid eye fatigue. Each participant selected the best shade match following the manufacturer’s instructions by selecting the value, chroma, and hue. The shade matching with the Vita-3D Master shade guide was done under the daylight illuminator (GTI Graphic Technology, NY, USA). The study was double blinded so that neither the examiners nor the participants knew the shade of the artificial teeth; only the principal investigator knew the correct shade. The Easy Shade Compact device was used according to the manufacturer’s instructions. It was calibrated after each participant’s usage. Since there is no contamination, the shield was not placed on the probe. The probe was touching the middle third of the tooth, and the shade tab mode was used for quality control.
2.3.
Statistical analysis
The results were analysed with SPSS version 19 and 95% confidence intervals. Frequencies and Chi-square tests were used to analyse the data, with a = 0.05 and significance set at P < 0.05.
3.
Results
Table 1 – Student class listing by frequency. Education level
Frequency Valid Percent
3rd Year
4th Year
5th Year
6th Year
Intern
Total
43 21.1
35 17.2
45 22.1
41 20.1
40 19.6
204
The overall ability for all students was low (36.3%) with the visual method (Table 2). There was not a statistical difference for experience in terms of ability to select the correct shade (P = 0.177). Table 3 also shows the lack of a significant gender difference in ability to visually select the correct matching shade (P = 0.560).
50
journal of dentistry 42 (2014) 48–52
Table 2 – Test correct by students class. P = 0.452. Types of shade matching
Groups Group 1 (3rd, 4th, 5th year)
Group 2 (6th Year, Intern)
41 (33.3%) 99 (80.5%)
33 (40.7%) 65 (80.2%)
Visual correct count (%) Easy shade correct count (%)
Total
P value
74 (36.3%) 164 (80.4%
0.0177% 0.552%
Table 3 – Test correct by gender. Types of shade matching
Gender
Visual correct count (%) Easy shade correct count (%)
Male
Female
35 (34.3%) 82 (80.4%)
39 (38.2%) 82 (80.4%)
Table 4 – Easy shade correct vs. test correct P = .098. Types of shade matching Easy shade? Yes count (%) No count (%) Total count (%)
Visual test correct
Total
Yes
No
64 (39.0%)
100 (61.0%)
164 (100.0%)
10 (25.0%) 74 (36.3%)
30 (75.0%) 130 (63.7%)
40 (100.0%) 204 (100.0%)
In contrast, 80.4% of participants (n = 164) gauged the correct shade using the Easy Shade Compact machine. Student experience had no significant influence (P < 0.552) (Table 2), and neither did gender (Table 3), as males and females equally mastered the use of the Easy Shade Compact device (P = 1.0). When the visual and Easy Shade methods were compared, 61.0% of those who could not match shades visually could do so with the Easy Shade (Table 4). Odds ratio (OR) analysis (Table 5) comparing the visual and Easy Shade methods revealed that students were 1.92 times less likely to match correctly using the visual method than to do so using the Easy Shade machine (OR = 1.92, 95% confidence interval, 0.879 to 4.194, P = 0.098).
4.
Discussion
About 30% of undergraduate students and interns at the Faculty of Dentistry at KAU participated in this study. All had
Table 5 – Odds ratio and relative risk. Easy shade correct vs. test correct. Value
Odds ratio for visual correct (correct/incorrect) For cohort easy shade correct = correct For cohort easy shade correct = incorrect No. of valid cases
95% confidence interval Lower
Upper
1.920
0.879
4.194
1.124
0.987
1.281
0.586
0.304
1.129
204
Total
P value
74 (36.3%) 164 (80.4%)
0.56 1.00
comparable age ranges and were divided into two groups based on education level. The Vita-3D Master Shade Guide System was chosen because it has resulted in higher colour match in studies comparing it with the Vitapan classical shade guide.11,20–22 It has been reported that Vita Classic shade guide tabs are not systematically distributed in the colour space relevant to human teeth, and that there is even overlap.23 Human visual colour assessments are a summation of physiological and psychological responses to a colour stimulus. The perception of colour by an observer is subjective, resulting in varied and unpredictable differences in colour evaluation and matching among clinicians.23,24 Researches reported that various factors such as the type and intensity of light source, angle of incidence, tooth texture and contour will complicate the shade taking procedure. However, participants with CVD were excluded here by use of the Ishihara test, one of the most commonly used screening tools for CVDs.11 This decision also took into account the results of Davison and Myslinski, who reported that colourdefective dental personnel make significantly greater errors in hue and chroma selection than normal-vision dental personnel.10 In this study, the shade matching for an artificial tooth with the conventional visual method differed significantly in percentage of correct matches (36.3%) compared with results for the Easy Shade Compact device (80.4%). With the visual technique, those 36.3% of participants chose the correct shade (value, chroma, and hue), but 22% had only the correct value and chroma. The participants found that this spectrophotometer was much easier to use than the conventional visual method. In addition, they did not have to worry about the light source, environment, or background. Our results are in agreement with others who have reported better results with spectrophotometer colour matching compared to visual shade assessment.17,25–28 Paul et al. suggested that spectrophotometric shade analysis is more accurate and more reproducible compared with human shade assessment.29 It has been mentioned that this approach can serve as a reliable addition in colour matching and enhances the level of shade analysis, communication, interpretation, and fabrication of dental restorations.30 Witkowski et al. reported that the accuracy and reproducibility of dental shade selection using a digital spectrophotometer with respect to examiner and illumination conditions reflected the reliability of the device.31
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In this study, the two groups organized by education level did not differ in their shade matching results. This finding is in agreement with those of previous groups13,27,28 that reported no effect on results of experience in shade matching. In contrast, however, Della Bona and colleagues reported that previous training in shade matching and clinical experience in dentistry played important roles in shade matching accuracy.32 In terms of gender, the traditional belief has been that women are more capable of matching colours than men,13 and other researchers have evaluated whether a difference exists between men and women in terms of shade matching ability.14,33–38 Haddad et al. found that females achieved significantly better shade matching results than males.13 Surprisingly, Miranda reported that men were more successful in discriminating shades.33 However, investigators in other studies have been unable to identify a significant influence of sex on shade matching ability.14,16,31,34,35 In agreement, our results showed that sex is not an important factor in shade matching and that male and female participants did not differ using either technique. Comparing the visual and Easy Shade methods, 61.0% of those who could not match shades visually for an artificial tooth could do so with Easy Shade. In addition, students were 1.92 times less likely to match correctly with the visual approach than to do so using the Easy Shade machine. The limitations of this study are that one shade was selected, but we were concerned about eye fatigue. To compensate for that limitation, the number of participants was increased. However artificial tooth was used to mimic the clinical situation.
5.
Conclusion
Within the limitations of this study, the shade matching device (Easy Shade Compact) was significantly better than the conventional visual method in yielding accurate results. Males and females did not differ significantly in outcomes with either technique, and experience had no significant influence on shade matching quality when selecting shade for artificial tooth.
Conflict of interest statement No conflict of interest is declared for this work.
Acknowledgments This Project was funded by Deanship of Scientific Research (DSR), King Abdulaziz University, Jeddah, under grant no. 1433/165/500. The author, therefore, acknowledge with thanks the technical and financial support. The author would like to express her sincere thanks to Professor Garnett Henley, Howard University College of Dentistry, USA, and Dr. Hanan Kadi in King abdulaziz University for their assistance in the statistical analysis. However she appreciates the help of Dr. Ghada Essa and Dr. Ghadi Muamenah in collecting the clinical data.
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