Perception of Dental Esthetics in Different Cultures Christian Mehl, DMD, PhDa/Stefan Wolfart, DMD, PhDb/Oliver Vollrath, Dipl Mathc/ Hans-Jürgen Wenz, DMD, PhDd/Matthias Kern, DMD, PhDe Purpose: The purpose of this study was to compare patients’ and dentists’ perception of dental appearance. Materials and Methods: Based on internationally accepted guidelines about dental esthetics, a questionnaire was developed to measure “dental appearance” (QDA). Eleven items defined a QDA score (0 = “absolutely dissatisfied” to 100 = “absolutely satisfied”). The QDA was completed by 29 patients (21 women, 8 men) before and after a complete oral rehabilitation that included restoration of the maxillary anterior teeth. Overall, 94 dentists from four countries (Germany, the United Kingdom, China, and Switzerland) evaluated the esthetics before and after rehabilitation on a visual analog scale (VAS: 0 = “absolutely unesthetic” to 100 = “absolutely esthetic”). Results: Patients and dentists of all countries found a significant esthetic improvement after treatment (P ≤ .0001). Significant differences could be found when comparing the evaluation of the dentists from the various countries among one another and with the patients’ self-evaluation (P ≤ .05). With the exception of the professional rating of the initial situation, no gender-related differences could be found in any of the test groups. Conclusions: In daily practice, it seems of utmost importance for dentists to incorporate the patients’ feedback in order to avoid esthetic treatment failures. Int J Prosthodont 2014;27:523–529. doi: 10.11607/ijp.3908
N
ew materials and techniques have fueled a dental esthetics cultural revolution.1 In addition, contemporaneous computer-driven idealization of the human appearance in the media has left an impact on patients.2,3 As beauty standards increase, and can even affect patients’ financial success,4 dentists must now address the rising esthetic expectations of today’s patients.3
aResearcher,
Department of Prosthodontics, Propaedeutics, and Dental Materials, Christian-Albrechts University at Kiel, Kiel, Germany; Private Practice, Munich, Germany. bProfessor, Chair, Department of Prosthodontics and Dental Materials, Medical Faculty, RWTH Aachen University, Aachen, Germany. cAssistant Professor, Institute of Medical Informatics and Statistics, University Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany. dProfessor, Department of Prosthodontics, Propaedeutics and Dental Materials, Christian-Albrechts University at Kiel, Kiel, Germany. eProfessor, Chair, Department of Prosthodontics, Propaedeutics and Dental Materials, Christian-Albrechts University at Kiel, Kiel, Germany. Correspondence to: Dr Christian Mehl, Department of Prosthodontics, Propaedeutics, and Dental Materials, Christian-Albrechts University at Kiel, Arnold-Heller-Straße 16, 24105 Kiel, Germany. Fax: +49-89-574578. Email: [email protected] ©2014 by Quintessence Publishing Co Inc.
Restoring biomedical and mechano-technical aspects of a patient’s dentition are traditional goals of dentistry.5 Since patients increasingly demand esthetic procedures,1,3 and positive effects of such treatments on patients’ confidence and quality of life were identified,6 a variety of influential factors on dental esthetics have been evaluated.7–9 In order to base esthetics scientifically, several authors have presented guidelines regarding tooth proportions and gold standard values.7–9 For dentists in general, objective and quantifiable measurements are considered to be conventional indicators of esthetic success or failure.7–9 Hence, a harmoniously balanced smile judged from a professional perspective is assumed to arise as a result of the ideal interaction of dental and gingival beauty criteria.10,11 However, dental appearance is also influenced and measured by more abstract, psychological factors such as ideal body image, self-image, and personal motivation.5,12 Moreover, gender-related and cultural differences seem to play a significant role.10,13–16 Subsequently, it seems to be difficult to address individual needs with specific guidelines that will lead to consistent results.17 Significant differences between patients’ and dentists’ esthetic perceptions and assessment of the degree of esthetic treatment needs were revealed in several studies.17–20 Generally, dentists observe a greater need for esthetic treatment than patients.20,21
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Perception of Dental Esthetics
a
b
c
d
Fig 1 Examples of a rehabilitation of the anterior maxilla with full-coverage fixed dental prostheses and veneers (a) before oral rehabilitation during strong smiling (b) and with retracted lips and (c) after oral rehabilitation during strong smiling (d) and with retracted lips.
In addition, there is evidence that the cultural backgrounds of laypersons and professionals seem to play a significant role in judging digitally altered photographs.15,16 To the authors’ knowledge, little is known about self- and professional assessment and intercultural differences before and after complete oral rehabilitations. In order to avoid clinically common misunderstandings regarding esthetics, it would be of interest to learn whether professional judgment and patients’ self-evaluation differ significantly. Furthermore, differences related to culture or sex could significantly influence professionals’ evaluation of dental appearance. The purpose of this study was to compare esthetic perceptions of complex oral rehabilitations, including the anterior teeth of the maxilla, between patients and dentists and to evaluate cultural and sex-related differences of four countries: Germany (Ger), Switzerland (CH), China, and the United Kingdom (UK).
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Materials and Methods Participants and Study Procedures Twenty-nine patients (8 men, 21 women) with esthetic dental problems were treated between January 1 and September 30, 2009, in a private clinic in London. The mean age of the patients was 38 ± 8 years (range: 22 to 67 years); they were unpaid volunteers. The materials and methods of the current study have been described in detail in a previous study.17 In summary, each patient received a complete oral rehabilitation according to a synoptic treatment concept, including at least one central incisor (Fig 1). The treatment included an initial oral hygiene phase and the removal of all dental diseases (eg, decay, periapical or periodontal inflammations, inadequately positioned third molars) prior to esthetic treatment. Orthodontic treatment was not performed in any of the patients.
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Mehl et al
One clinician and one laboratory performed the dental treatment to reduce variation.17 Patients were allowed to give their input into all aspects of their restoration and even to decide personal “nonobjectifiable” dental aspects, like the color. A large variety of restorations were chosen to (1) suit the patients’ needs and (2) to have a representative amount of all treatment options that are available to dentists nowadays. All presentations were introduced by a verbal sequence with instructions for the participants that were translated by a bilingual native dental professional (ie, backwardforward translating). Investigators aimed to keep variables such as different presentation rooms, differences in lighting, and different projectors to a minimum. After the initial treatment, an impression was taken and a wax-up of the teeth to be treated produced, which was based on gold standard values7–9 and an esthetic checklist.22 At the mock-up and temporary stage, the patients’ feedback regarding every point on the checklist was incorporated to produce the final work (eg, color, texture, length, width). In compromised situations, consensus was reached and the course of action determined together with the patient. The patients were asked to complete a questionnaire asking for “Satisfaction with one’s own dental appearance” twice (QDA; Table 1),12,17,23 initially after the removal of all dental diseases and 2 weeks after esthetic rehabilitation at the final recall session. The esthetic rehabilitation was performed only with fixed solutions (120 veneers, 69 crowns, 13 fixed dental prostheses, 1 resin-bonded fixed dental prosthesis, and 11 fillings; for frequency of treated teeth, see Table 2). In addition, whitening of nonrestored teeth was performed for two patients to avoid differences in color between artificial and natural teeth. Two standardized digital photographs before and after oral rehabilitation (EOS 50D, Canon; Fig 1) were used to assess esthetic appearance by 94 dentists from four different countries (46 men, 48 women, mean age: 32 ± 8.6 years; Ger, 14 men/16 women: 33 ± 7.6 years; CH, 9 men/5 women: 35 ± 4.8 years; China, 10 men/20 women: 25 ± 3 years; and UK, 12 men/8 women: 39 ± 10 years). As displays and projectors often render the same image differently (hue, value, etc), a picture calibration was performed (Spider4Elite, Datacolor, Dietlikon). All dentists were practicing dentistry at universities or in private practice. The mean professional experience was 7 ± 8 years (Ger, 6 ± 8 years; CH, 7 ± 5 years; China, 3 ± 3 years; UK, 14 ± 11 years). Statistical Analysis The data were statistically analyzed using SPSS for Windows version 18.0 (SPSS) at a level of significance of P ≤ .05. Since the data were not distributed
Table 1 Q uestionnaire: “Satisfaction with One’s Own Dental Appearance” No.
Item
Questions 1–6 asked in a positive way Q1
I am content with the appearance of my teeth.
Q2
I am content with the size of my teeth.
Q3
I am content with the shape of my teeth.
Q4
I am content with the color of my teeth.
Q5
I am content with the position of my teeth.
Q6
I am content with the appearance of my gums.
Questions 7–11 asked in a negative way Q7
I tend to hide my teeth.
Q8
I wish I had other teeth.
Q9
I feel rather old because of my teeth.
Q10
I am dissatisfied with the black hole disease between my teeth.
Q11
I am dissatisfied that my teeth are recognized as artificial.
Table 2 Number and Frequency of Teeth Treated Number of patients
2
6
3
2
6
1
1
1
1
6
Number of teeth treated
1
2
3
4
6
8
10
16
20
all
normally (Kolmogorov-Smirnov and Shapiro-Wilk test), nonparametric tests were employed. Kruskal-Wallis tests and Mann-Whitney U tests for independent samples were used to compare data before and after oral rehabilitation, to evaluate differences among the professionals, and for the comparison of professional evaluations with the patients’ self-evaluations. In order to calculate test-retest reliability, Mann-Whitney U tests for dependent samples were used. MannWhitney U tests and Jonckheere-Terpstra tests were performed to evaluate sex-related differences. All P values were corrected according to BonferroniHolm for multiple testing.24
Results A summary of the data and the statistical analysis can be found in Tables 3 to 5. The median values of the visual analog scale (VAS)/QDA values of 46 (before oral rehabilitation) and 86 (after) showed a significant improvement of the self-perception of dental esthetics of the patients (P ≤ .0001). The median VAS value was 32 (Ger), 34 (CH), 26 (China), and 31 (UK) for the photograph showing the patient with retracted lips (P_teeth) and 29 (Ger), 38 (CH), 29 (China), and 30 (UK) for the photograph of the patient showing a strong smile (P_smile) before rehabilitation. After rehabilitation, the median VAS value improved to 61
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Perception of Dental Esthetics
Table 3a Patients’ Median Self-Evaluation Results from the Dental Appearance Questionnaire (QDA) (n = 29)
Before treatment
Percentiles (25th; 75th)
After treatment
Percentiles (25th; 75th)
Difference
46
33; 63
86
81; 94
35
27; 53
P ≤ .001
QDA sum score*
Percentiles Comparison (25th; 75th) before/after treatment
*QDA was judged on a visual analog scale (endpoints 0 = “not at all” and 100 = “very much”).
Table 3b Dentists’ Median Evaluation Scores Using the Visual Analog Scale Country and evaluation type Germany P_teeth P_smile Switzerland P_teeth P_smile China P_teeth P_smile United Kingdom P_teeth P_smile
n
Before treatment
Percentiles (25th; 75th)
After treatment
Percentiles (25th; 75th)
Differences
Percentiles (25th; 75th)
Comparisons before/ after treatment (P ≤ )
32 29
28; 36 25; 35
61 60
54; 65 56; 64
26 29
22; 34 21; 34
.001 .001
34 38
31; 38 34; 41
57 56
52; 62 52; 58
32 16
14; 29 12; 23
.001 .001
26 29
20; 32 22; 32
53 59
48; 61 49; 64
28 29
18; 34 18; 37
.001 .0001
31 30
27; 36 24; 39
69 68
59; 74 61; 78
34 38
24; 44 27; 47
.001 .001
30
14
30
20
P_smile = photographs showing a strong smile before and after treatment; P_teeth = maxillary anterior teeth with retracted lips before and after treatment.
Table 4a Comparison of the Dentists’ Esthetic Perceptions Among Four Countries* Evaluation type P_teeth before P_teeth after P_teeth difference before/after P_smile before P_smile after P_smile difference before/after
Overall* (n = 94)
CH/Ger † (n = 14/31)
China/Ger † (n = 30/30)
UK/Ger † (n = 20/30)
China/CH† (n = 30/14)
UK/CH† (n = 20/30)
UK/China† (n = 20/30)
0.002 0.0001 0.05 0.005 0.0001 0.0001
.2 .2 .1 .008 .04 .008
.008 .02 .9 .3 .4 .99
.8 .01 .09 .8 .008 .02
.005 .2 .2 .0006 .3 .009
.2 .008 .01 .03 .0006 .0006
.02 .0006 .05 .4 .0006 .02
*Kruskal-Wallis test; †P value.
Table 4b Comparisons Between the Countries and the Patients’ Self-Evaluation Evaluation type
Overall* (n = 94)
Pat/Ger † (n = 29/30)
Pat/CH† (n = 29/14)
Pat/China† (n = 29/30)
Pat/UK† (n = 29/20)
P_teeth before P_teeth after P_teeth difference before/after P_smile before P_smile after P_smile difference before/after
0.0001 0.0001 0.009 0.0001 0.0001 0.01
.0004 .0004 .009 .0004 .0004 .01
.016 .0004 .006 .05 .0004 .0004
.0004 .0004 .006 .0004 .0004 .02
.004 .0004 .3 .006 .0004 .99
Pat = patient’s self-evaluation. *Kruskal-Wallis test; †P value.
(Ger), 57 (CH), 53 (China), and 69 (UK) for P_teeth and to 60 (Ger), 56 (CH), 59 (China), and 68 (UK) for P_smile. Both P_smile and P_teeth were significantly different before and after rehabilitation for the patients’ self-evaluation and for every country (P ≤ .0001). Overall, the dentists from the four countries rated the esthetic appearance of the patients differently, regardless of the test mode (P_teeth, P_smile, differences; Kruskal-Wallis test, P ≤ .05). When evaluating country-related differences for P_teeth before
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treatment, the comparisons China/CH-Ger-UK showed significant differences between groups (P ≤ .02; Table 3). After treatment, all comparisons except CH/ Ger and China/CH revealed significant differences between groups (P ≤ .05). When evaluating countryrelated differences for P_smile before treatment, the comparisons CH/Ger, China/CH and UK/CH demonstrated significant differences (P ≤ .03; Table 4a). After treatment, all comparisons except China/ Ger and China/CH revealed significant differences (P ≤ .05).
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Mehl et al
Table 5 Comparison of the Gender-Related Esthetic Perceptions of the Dentists and the Patients* Gender-related results (median [25th; 75th percentiles]) Dent F
Dent M
Pat F
Pat M
48
46
21
8
P_teeth before
28 (23; 33)
33 (28; 38)
Before
45 (33; 58)
55 (35; 65)
P_teeth after
58 (50; 65)
61 (54; 65)
After
86 (80; 92)
92 (84; 100)
Difference
43 (31; 53)
32 (16; 52)
n
P_teeth difference before-after
29 (22; 35)
27 (19; 35)
P_smile before
30 (22; 33)
32 (27; 41)
P_smile after
58 (52; 65)
61 (56; 66)
P_smile difference before-after
29 (20; 38)
28 (19; 37) Gender-related comparisons
Dent F vs Dent M
Pat F vs Pat M
P_teeth before
0.02
Before
0.3
P_teeth after
0.1
After
0.2
P_teeth difference before-after
0.5
Difference
0.5
P_smile before
0.04
P_smile after
0.1
P_smile difference before-after
0.7
*Pooled data were used for the dentists’ judgments and Mann-Whitney U test was used to find the patients’. Dent F = dentist female; Dent M = dentist male. Pat F = patient female; Pat M = patient male. P_smile = photographs showing a strong smile before and after treatment; P_teeth = maxillary anterior teeth with retracted lips before and after treatment.
Significant differences could be found as well when comparing the dentists’ to the patients’ judgment (P_teeth, P_smile, differences; Kruskal-Wallis test, P ≤ .003). With regard to the calculations between the individual countries and the patients’ self-evaluation (Pat), significant differences could be found for almost all comparisons (P ≤ .05) except for the comparison Pat/UK P_teeth/P_smile difference before/ after (P > .05; Table 4b). Sex-related differences were statistically not significant for both patients and professionals, with the exception of female professionals judging the initial situation (P_smile and P_teeth), who were more critical than male professionals (Table 5; P ≤ .05). Although statistically not significant, using Mann-Whitney U tests, a tendency similar to the judgment of the female professionals could be identified for the female patients’ ratings (Jonckheere-Terpstra test, P ≤ .001). Test-retest reliability of the professional assessment was tested with a test-retest procedure. For the evaluation and reevaluation of P_smile and P_teeth, significant differences were revealed for four out of the 16 tests (P_teeth before/after for Ger, P_teeth before for CH, and P_teeth after for UK; P ≤ .05). No difference could be found when test-retesting P_smile (P > .05). No difference could be found when comparing P_smile and P_teeth (P > .05).
Discussion Interestingly, despite both judging a significant improvement, the professionals’ and patients’ ratings hardly matched. The before/after treatment difference conflicted for the UK-Pat comparison only, which could be caused by the way the difference was mathematically calculated or by the fact that the treatments were performed in that cultural area.16 The general phenomenon could possibly be explained by the fact that most of the restorations had to be made with compromises (eg, lip line, gum, or anatomical characteristics) and the patients considered this fact in their judgment. As treatment proceeded, the patients in the current study became conscious of the anatomical limitations of their own condition. As a result, a more “merciful” approach to one’s restoration evolved. In contrast, dentists, especially those who might feel “tested” in a school-like environment, may have had very high requirements and, therefore, might have judged the esthetic outcome more critically. In addition, complex concepts such as esthetic perception, ideal body image, and self-image are affected by emotional and personality factors that develop during the life cycle.5,25 This can lead to a varying subjective esthetic perception and inhomogenous results within the patient group.
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Perception of Dental Esthetics
Furthermore, economic status and education level,26 as well as sex, age, and relation to the assessed person, seem to play an important role.27 To show the complexity of patients’ perceptions, a study reported that girls were more critical of their own tooth color than boys were about theirs; however, parents and dentists were more critical of boys’ tooth color than of girls’. Younger patients were more critical than older patients; parents of younger patients were less critical than those of older patients.27 In contrast, dentists are trained to objectify more precisely factors leading to an unesthetic smile. This difference in esthetic judgment between patients and dentists is in agreement with several other studies.17–19,28 But not only the patients’ assessments seemed to be inhomogenous; the literature reports differences within the dental profession and specializations itself.21,29,30 In previous studies, sex, age, and experience seemed not to influence the professional judgment of dental appearance significantly.10,17 These results could be confirmed in the current study with the exception of female professionals judging the initial situation more critically than their male counterparts. Although the results were not statistically significant, a tendency toward similar results could be observed for female patients. With regard to cultural differences, participants of the various countries very often disagreed when evaluating the patients’ esthetics. The nonsignificant results regarding the comparisons of the differences of P_smile and P_teeth could be explained by the mathematical calculation of the differences, where only the result of the calculation (after restoration – before restoration = difference) is compared. The more critical Chinese judgment of the initial and the final situation is more relevant to the interpretation of the data in that aspect. The results seemed to reflect that European dentists may have a slightly different perception of dental esthetics than do Chinese. But even the European judgment was not consistent, as the differences between the countries suggested. In addition, possible explanations for the encountered differences between the countries’ dentists could have been caused by the teaching and dogmas in the respective dental schools. Dentists who practice in the United Kingdom are well adapted to and, sometimes, even economically dependent on the esthetic needs and demands of patients in their daily practice.1 In contrast, dentists who practice in more conservative countries such as Switzerland may rate artificially looking (eg, too white) teeth as unnatural and thus not esthetically acceptable. A lower rating of the esthetic appearance of the patients by the dentists who practice in China could be explained by the fact that Chinese dentists have had little contact with esthetic
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procedures as the need in the population does not exist yet.31,32 With regard to the use of P_teeth and P_smile, no statistically significant differences could be found. However, the reliability testing showed significant differences for P_teeth for three of eight professional ratings in contrast to P_smile, where no differences could be found. Hence, when evaluating esthetic questions, it could be advantageous to use photographs showing the dynamic aspect of the dental appearance, as well, even if the lips are covering gingival or restorative elements. Still, the lack of reliability for P_teeth has to be seen as a limitation in this study. In fact, this lack of reliability is hardly surprising. When looking at what is commonly perceived as the simplest task in dentistry—finding and classifying decay—significant inter- and intrarater differences were reported.33,34 Hence, in a far more complex area such as esthetic rehabilitation, variety seemed commonplace but may be able to be reduced with constant baseline training/calibration like in other areas of dentistry.33 It would be of interest to know in which areas the most judgment and greatest differences between the patient and the dentists lie (eg, color, shape, symmetry of treatment, type of restoration).
Conclusions Under the limitations of this study, the following conclusions can be drawn: •• Professionals and patients judged a significant improvement of dental esthetics after treatment in the esthetic zone. Using esthetic guidelines, following a standardized treatment concept, and, most importantly, incorporating the patients’ feedback in the treatment seem to lead to more predictable results. •• Dentists from different cultures may judge dental esthetics differently. •• However, the judgment of esthetic appearance seems to conflict when patients evaluate their own restorations and the same restorations are rated by independent professionals. •• Gender only seems to influence professional judgment with regard to the initial dental appearance.
Acknowledgments The authors wish to express their gratitude to Mr Sönke Harder (Munich, Germany), Mrs Jun Lin (Hangzhou, China), and Mr Juerg Luder (Zurich, Switzerland) for their dedication in organizing the events. The authors also would like to thank all participating colleagues. The authors are grateful to Mrs Anna Trinkler (London, United Kingdom) for data collection and tabulating. The authors reported no conflicts of interest related to this study.
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References 1. Priest G, Priest J. Promoting esthetic procedures in the prosthodontic practice. J Prosthodont 2004;13:111–117. 2. Theobald AH, Wong BK, Quick AN, Thomson WM. The impact of the popular media on cosmetic dentistry. N Z Dent J 2006;102:58–63. 3. Asbury A. Putting your money where your mouth is: The influence of American consumer culture on contemporary dentistry. J Am Coll Dent 2011;78:22–26. 4. Lorenz K. Do pretty people earn more? CNN News, Time Warner 2005. 5. Sheets CG, Levinson N. Psychodynamic factors contributing to esthetic dental failures. Compendium 1993;14:1614–1620. 6. Davis LG, Ashworth PD, Spriggs LS. Psychological effects of aesthetic dental treatment. J Dent 1998;26:547–554. 7. Magne P, Belser U. Natural oral esthetics. In: Bonded Porcelain Restorations in the Anterior Dentition: A Biomimetic Approach. Chicago: Quintessence; 2002:1–128. 8. Wolfart S, Thormann H, Freitag S, Kern M. Assessment of dental appearance following changes in incisor proportions. Eur J Oral Sci 2005;113:159–165. 9. Sterrett JD, Oliver T, Robinson F, Fortson W, Knaak B, Russell CM. Width/length ratios of normal clinical crowns of the maxillary anterior dentition in man. J Clin Periodontol 1999;26:153–157. 10. Wolfart S, Quaas AC, Freitag S, Kropp P, Gerber WD, Kern M. Subjective and objective perception of upper incisors. J Oral Rehabil 2006;33:489–495. 11. Allen EP. Use of mucogingival surgical procedures to enhance esthetics. Dent Clin North Am 1988;32:307–330. 12. Wolfart S, Quaas AC, Freitag S, Kropp P, Gerber WD, Kern M. General well-being as an important co-factor of self-assessment of dental appearance. Int J Prosthodont 2006;19:449–454. 13. Carlsson GE, Wagner IV, Odman P, et al. An international comparative multicenter study of assessment of dental appearance using computer-aided image manipulation. Int J Prosthodont 1998;11:246–254. 14. Bekker MHJ, Croon MA, Vermaas S. Inner body and outward appearance—The relationship between orientation toward outward appearance, body awareness and symptom perception. Pers Indiv Diff 2002;33:213–225. 15. McLeod C, Fields HW, Hechter F, Wiltshire W, Rody W Jr, Christensen J. Esthetics and smile characteristics evaluated by laypersons. Angle Orthod 2011;81:198–205. 16. Sharma N, Rosenstiel SF, Fields HW, Beck FM. Smile characterization by U.S. white, U.S. Asian Indian, and Indian populations. J Prosthet Dent 2012;107:327–335. 17. Mehl CJ, Harder S, Kern M, Wolfart S. Patients’ and dentists’ perception of dental appearance. Clin Oral Investig 2011;15:193–199. 18. Brisman AS. Esthetics: A comparison of dentists’ and patients’ concepts. J Am Dent Assoc 1980;100:345–352.
19. Neumann LM, Christensen C, Cavanaugh C. Dental esthetic satisfaction in adults. J Am Dent Assoc 1989;118:565–570. 20. Tortopidis D, Hatzikyriakos A, Kokoti M, Menexes G, Tsiggos N. Evaluation of the relationship between subjects’ perception and professional assessment of esthetic treatment needs. J Esthet Restor Dent 2007;19:154–162. 21. Juggins KJ, Nixon F, Cunningham SJ. Patient- and clinicianperceived need for orthognathic surgery. Am J Orthod Dentofacial Orthop 2005;128:697–702. 22. Chiche GJ, Pinault A. Esthetics of Anterior Fixed Prosthodontics. Chicago: Quintessence, 1994. 23. Mehl C, Kern M, Freitag-Wolf S, Wolfart M, Brunzel S, Wolfart S. Does the Oral Health Impact Profile questionnaire measure dental appearance? Int J Prosthodont 2009;22:87–93. 24. Holm S. A simple sequentially rejective multiple test procedure. Scand J Stat 1979;6:65–70. 25. Haimovitz D, Lansky LM, O’Reilly P. Fluctuations in body satisfaction across situations. Int J Eat Disord 1993;13:77–84. 26. Celebic A, Knezovic-Zlataric D, Papic M, Carek V, Baucic I, Stipetic J. Factors related to patient satisfaction with complete denture therapy. J Gerontol A Biol Sci Med Sci 2003;58:M948–M953. 27. Shulman JD, Maupome G, Clark DC, Levy SM. Perceptions of desirable tooth color among parents, dentists and children. J Am Dent Assoc 2004;135:595–604; quiz 654–595. 28. Donitza A. Creating the perfect smile: Prosthetic considerations and procedures for optimal dentofacial esthetics. J Calif Dent Assoc 2008;36:335–340, 342. 29. Kokich VO, Kokich VG, Kiyak HA. Perceptions of dental professionals and laypersons to altered dental esthetics: Asymmetric and symmetric situations. Am J Orthod Dentofacial Orthop 2006; 130:141–151. 30. Kiekens RM, Maltha JC, van ‘t Hof MA, Straatman H, KuijpersJagtman AM. Panel perception of change in facial aesthetics following orthodontic treatment in adolescents. Eur J Orthod 2008; 30:141–146. 31. Marino R, Morgan M, Kiyak A, Schwarz E, Naqvi S. Oral health in a convenience sample of Chinese older adults living in Melbourne, Australia. Int J Public Health 2012;57:383–390. 32. Du M, Petersen PE, Fan M, Bian Z, Tai B. Oral health services in PR China as evaluated by dentists and patients. Int Dent J 2000; 50:250–256. 33. Nelson S, Eggertsson H, Powell B, et al. Dental examiners consistency in applying the ICDAS criteria for a caries prevention community trial. Community Dent Health 2011;28:238–242. 34. Brocklehurst P, Ashley J, Walsh T, Tickle M. Relative performance of different dental professional groups in screening for occlusal caries. Community Dent Oral Epidemiol 2012;40: 239–246.
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N
ew materials and techniques have fueled a dental esthetics cultural revolution.1 In addition, contemporaneous computer-driven idealization of the human appearance in the media has left an impact on patients.2,3 As beauty standards increase, and can even affect patients’ financial success,4 dentists must now address the rising esthetic expectations of today’s patients.3
aResearcher,
Department of Prosthodontics, Propaedeutics, and Dental Materials, Christian-Albrechts University at Kiel, Kiel, Germany; Private Practice, Munich, Germany. bProfessor, Chair, Department of Prosthodontics and Dental Materials, Medical Faculty, RWTH Aachen University, Aachen, Germany. cAssistant Professor, Institute of Medical Informatics and Statistics, University Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany. dProfessor, Department of Prosthodontics, Propaedeutics and Dental Materials, Christian-Albrechts University at Kiel, Kiel, Germany. eProfessor, Chair, Department of Prosthodontics, Propaedeutics and Dental Materials, Christian-Albrechts University at Kiel, Kiel, Germany. Correspondence to: Dr Christian Mehl, Department of Prosthodontics, Propaedeutics, and Dental Materials, Christian-Albrechts University at Kiel, Arnold-Heller-Straße 16, 24105 Kiel, Germany. Fax: +49-89-574578. Email: [email protected] ©2014 by Quintessence Publishing Co Inc.
Restoring biomedical and mechano-technical aspects of a patient’s dentition are traditional goals of dentistry.5 Since patients increasingly demand esthetic procedures,1,3 and positive effects of such treatments on patients’ confidence and quality of life were identified,6 a variety of influential factors on dental esthetics have been evaluated.7–9 In order to base esthetics scientifically, several authors have presented guidelines regarding tooth proportions and gold standard values.7–9 For dentists in general, objective and quantifiable measurements are considered to be conventional indicators of esthetic success or failure.7–9 Hence, a harmoniously balanced smile judged from a professional perspective is assumed to arise as a result of the ideal interaction of dental and gingival beauty criteria.10,11 However, dental appearance is also influenced and measured by more abstract, psychological factors such as ideal body image, self-image, and personal motivation.5,12 Moreover, gender-related and cultural differences seem to play a significant role.10,13–16 Subsequently, it seems to be difficult to address individual needs with specific guidelines that will lead to consistent results.17 Significant differences between patients’ and dentists’ esthetic perceptions and assessment of the degree of esthetic treatment needs were revealed in several studies.17–20 Generally, dentists observe a greater need for esthetic treatment than patients.20,21
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Perception of Dental Esthetics
a
b
c
d
Fig 1 Examples of a rehabilitation of the anterior maxilla with full-coverage fixed dental prostheses and veneers (a) before oral rehabilitation during strong smiling (b) and with retracted lips and (c) after oral rehabilitation during strong smiling (d) and with retracted lips.
In addition, there is evidence that the cultural backgrounds of laypersons and professionals seem to play a significant role in judging digitally altered photographs.15,16 To the authors’ knowledge, little is known about self- and professional assessment and intercultural differences before and after complete oral rehabilitations. In order to avoid clinically common misunderstandings regarding esthetics, it would be of interest to learn whether professional judgment and patients’ self-evaluation differ significantly. Furthermore, differences related to culture or sex could significantly influence professionals’ evaluation of dental appearance. The purpose of this study was to compare esthetic perceptions of complex oral rehabilitations, including the anterior teeth of the maxilla, between patients and dentists and to evaluate cultural and sex-related differences of four countries: Germany (Ger), Switzerland (CH), China, and the United Kingdom (UK).
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Materials and Methods Participants and Study Procedures Twenty-nine patients (8 men, 21 women) with esthetic dental problems were treated between January 1 and September 30, 2009, in a private clinic in London. The mean age of the patients was 38 ± 8 years (range: 22 to 67 years); they were unpaid volunteers. The materials and methods of the current study have been described in detail in a previous study.17 In summary, each patient received a complete oral rehabilitation according to a synoptic treatment concept, including at least one central incisor (Fig 1). The treatment included an initial oral hygiene phase and the removal of all dental diseases (eg, decay, periapical or periodontal inflammations, inadequately positioned third molars) prior to esthetic treatment. Orthodontic treatment was not performed in any of the patients.
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One clinician and one laboratory performed the dental treatment to reduce variation.17 Patients were allowed to give their input into all aspects of their restoration and even to decide personal “nonobjectifiable” dental aspects, like the color. A large variety of restorations were chosen to (1) suit the patients’ needs and (2) to have a representative amount of all treatment options that are available to dentists nowadays. All presentations were introduced by a verbal sequence with instructions for the participants that were translated by a bilingual native dental professional (ie, backwardforward translating). Investigators aimed to keep variables such as different presentation rooms, differences in lighting, and different projectors to a minimum. After the initial treatment, an impression was taken and a wax-up of the teeth to be treated produced, which was based on gold standard values7–9 and an esthetic checklist.22 At the mock-up and temporary stage, the patients’ feedback regarding every point on the checklist was incorporated to produce the final work (eg, color, texture, length, width). In compromised situations, consensus was reached and the course of action determined together with the patient. The patients were asked to complete a questionnaire asking for “Satisfaction with one’s own dental appearance” twice (QDA; Table 1),12,17,23 initially after the removal of all dental diseases and 2 weeks after esthetic rehabilitation at the final recall session. The esthetic rehabilitation was performed only with fixed solutions (120 veneers, 69 crowns, 13 fixed dental prostheses, 1 resin-bonded fixed dental prosthesis, and 11 fillings; for frequency of treated teeth, see Table 2). In addition, whitening of nonrestored teeth was performed for two patients to avoid differences in color between artificial and natural teeth. Two standardized digital photographs before and after oral rehabilitation (EOS 50D, Canon; Fig 1) were used to assess esthetic appearance by 94 dentists from four different countries (46 men, 48 women, mean age: 32 ± 8.6 years; Ger, 14 men/16 women: 33 ± 7.6 years; CH, 9 men/5 women: 35 ± 4.8 years; China, 10 men/20 women: 25 ± 3 years; and UK, 12 men/8 women: 39 ± 10 years). As displays and projectors often render the same image differently (hue, value, etc), a picture calibration was performed (Spider4Elite, Datacolor, Dietlikon). All dentists were practicing dentistry at universities or in private practice. The mean professional experience was 7 ± 8 years (Ger, 6 ± 8 years; CH, 7 ± 5 years; China, 3 ± 3 years; UK, 14 ± 11 years). Statistical Analysis The data were statistically analyzed using SPSS for Windows version 18.0 (SPSS) at a level of significance of P ≤ .05. Since the data were not distributed
Table 1 Q uestionnaire: “Satisfaction with One’s Own Dental Appearance” No.
Item
Questions 1–6 asked in a positive way Q1
I am content with the appearance of my teeth.
Q2
I am content with the size of my teeth.
Q3
I am content with the shape of my teeth.
Q4
I am content with the color of my teeth.
Q5
I am content with the position of my teeth.
Q6
I am content with the appearance of my gums.
Questions 7–11 asked in a negative way Q7
I tend to hide my teeth.
Q8
I wish I had other teeth.
Q9
I feel rather old because of my teeth.
Q10
I am dissatisfied with the black hole disease between my teeth.
Q11
I am dissatisfied that my teeth are recognized as artificial.
Table 2 Number and Frequency of Teeth Treated Number of patients
2
6
3
2
6
1
1
1
1
6
Number of teeth treated
1
2
3
4
6
8
10
16
20
all
normally (Kolmogorov-Smirnov and Shapiro-Wilk test), nonparametric tests were employed. Kruskal-Wallis tests and Mann-Whitney U tests for independent samples were used to compare data before and after oral rehabilitation, to evaluate differences among the professionals, and for the comparison of professional evaluations with the patients’ self-evaluations. In order to calculate test-retest reliability, Mann-Whitney U tests for dependent samples were used. MannWhitney U tests and Jonckheere-Terpstra tests were performed to evaluate sex-related differences. All P values were corrected according to BonferroniHolm for multiple testing.24
Results A summary of the data and the statistical analysis can be found in Tables 3 to 5. The median values of the visual analog scale (VAS)/QDA values of 46 (before oral rehabilitation) and 86 (after) showed a significant improvement of the self-perception of dental esthetics of the patients (P ≤ .0001). The median VAS value was 32 (Ger), 34 (CH), 26 (China), and 31 (UK) for the photograph showing the patient with retracted lips (P_teeth) and 29 (Ger), 38 (CH), 29 (China), and 30 (UK) for the photograph of the patient showing a strong smile (P_smile) before rehabilitation. After rehabilitation, the median VAS value improved to 61
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Perception of Dental Esthetics
Table 3a Patients’ Median Self-Evaluation Results from the Dental Appearance Questionnaire (QDA) (n = 29)
Before treatment
Percentiles (25th; 75th)
After treatment
Percentiles (25th; 75th)
Difference
46
33; 63
86
81; 94
35
27; 53
P ≤ .001
QDA sum score*
Percentiles Comparison (25th; 75th) before/after treatment
*QDA was judged on a visual analog scale (endpoints 0 = “not at all” and 100 = “very much”).
Table 3b Dentists’ Median Evaluation Scores Using the Visual Analog Scale Country and evaluation type Germany P_teeth P_smile Switzerland P_teeth P_smile China P_teeth P_smile United Kingdom P_teeth P_smile
n
Before treatment
Percentiles (25th; 75th)
After treatment
Percentiles (25th; 75th)
Differences
Percentiles (25th; 75th)
Comparisons before/ after treatment (P ≤ )
32 29
28; 36 25; 35
61 60
54; 65 56; 64
26 29
22; 34 21; 34
.001 .001
34 38
31; 38 34; 41
57 56
52; 62 52; 58
32 16
14; 29 12; 23
.001 .001
26 29
20; 32 22; 32
53 59
48; 61 49; 64
28 29
18; 34 18; 37
.001 .0001
31 30
27; 36 24; 39
69 68
59; 74 61; 78
34 38
24; 44 27; 47
.001 .001
30
14
30
20
P_smile = photographs showing a strong smile before and after treatment; P_teeth = maxillary anterior teeth with retracted lips before and after treatment.
Table 4a Comparison of the Dentists’ Esthetic Perceptions Among Four Countries* Evaluation type P_teeth before P_teeth after P_teeth difference before/after P_smile before P_smile after P_smile difference before/after
Overall* (n = 94)
CH/Ger † (n = 14/31)
China/Ger † (n = 30/30)
UK/Ger † (n = 20/30)
China/CH† (n = 30/14)
UK/CH† (n = 20/30)
UK/China† (n = 20/30)
0.002 0.0001 0.05 0.005 0.0001 0.0001
.2 .2 .1 .008 .04 .008
.008 .02 .9 .3 .4 .99
.8 .01 .09 .8 .008 .02
.005 .2 .2 .0006 .3 .009
.2 .008 .01 .03 .0006 .0006
.02 .0006 .05 .4 .0006 .02
*Kruskal-Wallis test; †P value.
Table 4b Comparisons Between the Countries and the Patients’ Self-Evaluation Evaluation type
Overall* (n = 94)
Pat/Ger † (n = 29/30)
Pat/CH† (n = 29/14)
Pat/China† (n = 29/30)
Pat/UK† (n = 29/20)
P_teeth before P_teeth after P_teeth difference before/after P_smile before P_smile after P_smile difference before/after
0.0001 0.0001 0.009 0.0001 0.0001 0.01
.0004 .0004 .009 .0004 .0004 .01
.016 .0004 .006 .05 .0004 .0004
.0004 .0004 .006 .0004 .0004 .02
.004 .0004 .3 .006 .0004 .99
Pat = patient’s self-evaluation. *Kruskal-Wallis test; †P value.
(Ger), 57 (CH), 53 (China), and 69 (UK) for P_teeth and to 60 (Ger), 56 (CH), 59 (China), and 68 (UK) for P_smile. Both P_smile and P_teeth were significantly different before and after rehabilitation for the patients’ self-evaluation and for every country (P ≤ .0001). Overall, the dentists from the four countries rated the esthetic appearance of the patients differently, regardless of the test mode (P_teeth, P_smile, differences; Kruskal-Wallis test, P ≤ .05). When evaluating country-related differences for P_teeth before
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treatment, the comparisons China/CH-Ger-UK showed significant differences between groups (P ≤ .02; Table 3). After treatment, all comparisons except CH/ Ger and China/CH revealed significant differences between groups (P ≤ .05). When evaluating countryrelated differences for P_smile before treatment, the comparisons CH/Ger, China/CH and UK/CH demonstrated significant differences (P ≤ .03; Table 4a). After treatment, all comparisons except China/ Ger and China/CH revealed significant differences (P ≤ .05).
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Table 5 Comparison of the Gender-Related Esthetic Perceptions of the Dentists and the Patients* Gender-related results (median [25th; 75th percentiles]) Dent F
Dent M
Pat F
Pat M
48
46
21
8
P_teeth before
28 (23; 33)
33 (28; 38)
Before
45 (33; 58)
55 (35; 65)
P_teeth after
58 (50; 65)
61 (54; 65)
After
86 (80; 92)
92 (84; 100)
Difference
43 (31; 53)
32 (16; 52)
n
P_teeth difference before-after
29 (22; 35)
27 (19; 35)
P_smile before
30 (22; 33)
32 (27; 41)
P_smile after
58 (52; 65)
61 (56; 66)
P_smile difference before-after
29 (20; 38)
28 (19; 37) Gender-related comparisons
Dent F vs Dent M
Pat F vs Pat M
P_teeth before
0.02
Before
0.3
P_teeth after
0.1
After
0.2
P_teeth difference before-after
0.5
Difference
0.5
P_smile before
0.04
P_smile after
0.1
P_smile difference before-after
0.7
*Pooled data were used for the dentists’ judgments and Mann-Whitney U test was used to find the patients’. Dent F = dentist female; Dent M = dentist male. Pat F = patient female; Pat M = patient male. P_smile = photographs showing a strong smile before and after treatment; P_teeth = maxillary anterior teeth with retracted lips before and after treatment.
Significant differences could be found as well when comparing the dentists’ to the patients’ judgment (P_teeth, P_smile, differences; Kruskal-Wallis test, P ≤ .003). With regard to the calculations between the individual countries and the patients’ self-evaluation (Pat), significant differences could be found for almost all comparisons (P ≤ .05) except for the comparison Pat/UK P_teeth/P_smile difference before/ after (P > .05; Table 4b). Sex-related differences were statistically not significant for both patients and professionals, with the exception of female professionals judging the initial situation (P_smile and P_teeth), who were more critical than male professionals (Table 5; P ≤ .05). Although statistically not significant, using Mann-Whitney U tests, a tendency similar to the judgment of the female professionals could be identified for the female patients’ ratings (Jonckheere-Terpstra test, P ≤ .001). Test-retest reliability of the professional assessment was tested with a test-retest procedure. For the evaluation and reevaluation of P_smile and P_teeth, significant differences were revealed for four out of the 16 tests (P_teeth before/after for Ger, P_teeth before for CH, and P_teeth after for UK; P ≤ .05). No difference could be found when test-retesting P_smile (P > .05). No difference could be found when comparing P_smile and P_teeth (P > .05).
Discussion Interestingly, despite both judging a significant improvement, the professionals’ and patients’ ratings hardly matched. The before/after treatment difference conflicted for the UK-Pat comparison only, which could be caused by the way the difference was mathematically calculated or by the fact that the treatments were performed in that cultural area.16 The general phenomenon could possibly be explained by the fact that most of the restorations had to be made with compromises (eg, lip line, gum, or anatomical characteristics) and the patients considered this fact in their judgment. As treatment proceeded, the patients in the current study became conscious of the anatomical limitations of their own condition. As a result, a more “merciful” approach to one’s restoration evolved. In contrast, dentists, especially those who might feel “tested” in a school-like environment, may have had very high requirements and, therefore, might have judged the esthetic outcome more critically. In addition, complex concepts such as esthetic perception, ideal body image, and self-image are affected by emotional and personality factors that develop during the life cycle.5,25 This can lead to a varying subjective esthetic perception and inhomogenous results within the patient group.
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Furthermore, economic status and education level,26 as well as sex, age, and relation to the assessed person, seem to play an important role.27 To show the complexity of patients’ perceptions, a study reported that girls were more critical of their own tooth color than boys were about theirs; however, parents and dentists were more critical of boys’ tooth color than of girls’. Younger patients were more critical than older patients; parents of younger patients were less critical than those of older patients.27 In contrast, dentists are trained to objectify more precisely factors leading to an unesthetic smile. This difference in esthetic judgment between patients and dentists is in agreement with several other studies.17–19,28 But not only the patients’ assessments seemed to be inhomogenous; the literature reports differences within the dental profession and specializations itself.21,29,30 In previous studies, sex, age, and experience seemed not to influence the professional judgment of dental appearance significantly.10,17 These results could be confirmed in the current study with the exception of female professionals judging the initial situation more critically than their male counterparts. Although the results were not statistically significant, a tendency toward similar results could be observed for female patients. With regard to cultural differences, participants of the various countries very often disagreed when evaluating the patients’ esthetics. The nonsignificant results regarding the comparisons of the differences of P_smile and P_teeth could be explained by the mathematical calculation of the differences, where only the result of the calculation (after restoration – before restoration = difference) is compared. The more critical Chinese judgment of the initial and the final situation is more relevant to the interpretation of the data in that aspect. The results seemed to reflect that European dentists may have a slightly different perception of dental esthetics than do Chinese. But even the European judgment was not consistent, as the differences between the countries suggested. In addition, possible explanations for the encountered differences between the countries’ dentists could have been caused by the teaching and dogmas in the respective dental schools. Dentists who practice in the United Kingdom are well adapted to and, sometimes, even economically dependent on the esthetic needs and demands of patients in their daily practice.1 In contrast, dentists who practice in more conservative countries such as Switzerland may rate artificially looking (eg, too white) teeth as unnatural and thus not esthetically acceptable. A lower rating of the esthetic appearance of the patients by the dentists who practice in China could be explained by the fact that Chinese dentists have had little contact with esthetic
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procedures as the need in the population does not exist yet.31,32 With regard to the use of P_teeth and P_smile, no statistically significant differences could be found. However, the reliability testing showed significant differences for P_teeth for three of eight professional ratings in contrast to P_smile, where no differences could be found. Hence, when evaluating esthetic questions, it could be advantageous to use photographs showing the dynamic aspect of the dental appearance, as well, even if the lips are covering gingival or restorative elements. Still, the lack of reliability for P_teeth has to be seen as a limitation in this study. In fact, this lack of reliability is hardly surprising. When looking at what is commonly perceived as the simplest task in dentistry—finding and classifying decay—significant inter- and intrarater differences were reported.33,34 Hence, in a far more complex area such as esthetic rehabilitation, variety seemed commonplace but may be able to be reduced with constant baseline training/calibration like in other areas of dentistry.33 It would be of interest to know in which areas the most judgment and greatest differences between the patient and the dentists lie (eg, color, shape, symmetry of treatment, type of restoration).
Conclusions Under the limitations of this study, the following conclusions can be drawn: •• Professionals and patients judged a significant improvement of dental esthetics after treatment in the esthetic zone. Using esthetic guidelines, following a standardized treatment concept, and, most importantly, incorporating the patients’ feedback in the treatment seem to lead to more predictable results. •• Dentists from different cultures may judge dental esthetics differently. •• However, the judgment of esthetic appearance seems to conflict when patients evaluate their own restorations and the same restorations are rated by independent professionals. •• Gender only seems to influence professional judgment with regard to the initial dental appearance.
Acknowledgments The authors wish to express their gratitude to Mr Sönke Harder (Munich, Germany), Mrs Jun Lin (Hangzhou, China), and Mr Juerg Luder (Zurich, Switzerland) for their dedication in organizing the events. The authors also would like to thank all participating colleagues. The authors are grateful to Mrs Anna Trinkler (London, United Kingdom) for data collection and tabulating. The authors reported no conflicts of interest related to this study.
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19. Neumann LM, Christensen C, Cavanaugh C. Dental esthetic satisfaction in adults. J Am Dent Assoc 1989;118:565–570. 20. Tortopidis D, Hatzikyriakos A, Kokoti M, Menexes G, Tsiggos N. Evaluation of the relationship between subjects’ perception and professional assessment of esthetic treatment needs. J Esthet Restor Dent 2007;19:154–162. 21. Juggins KJ, Nixon F, Cunningham SJ. Patient- and clinicianperceived need for orthognathic surgery. Am J Orthod Dentofacial Orthop 2005;128:697–702. 22. Chiche GJ, Pinault A. Esthetics of Anterior Fixed Prosthodontics. Chicago: Quintessence, 1994. 23. Mehl C, Kern M, Freitag-Wolf S, Wolfart M, Brunzel S, Wolfart S. Does the Oral Health Impact Profile questionnaire measure dental appearance? Int J Prosthodont 2009;22:87–93. 24. Holm S. A simple sequentially rejective multiple test procedure. Scand J Stat 1979;6:65–70. 25. Haimovitz D, Lansky LM, O’Reilly P. Fluctuations in body satisfaction across situations. Int J Eat Disord 1993;13:77–84. 26. Celebic A, Knezovic-Zlataric D, Papic M, Carek V, Baucic I, Stipetic J. Factors related to patient satisfaction with complete denture therapy. J Gerontol A Biol Sci Med Sci 2003;58:M948–M953. 27. Shulman JD, Maupome G, Clark DC, Levy SM. Perceptions of desirable tooth color among parents, dentists and children. J Am Dent Assoc 2004;135:595–604; quiz 654–595. 28. Donitza A. Creating the perfect smile: Prosthetic considerations and procedures for optimal dentofacial esthetics. J Calif Dent Assoc 2008;36:335–340, 342. 29. Kokich VO, Kokich VG, Kiyak HA. Perceptions of dental professionals and laypersons to altered dental esthetics: Asymmetric and symmetric situations. Am J Orthod Dentofacial Orthop 2006; 130:141–151. 30. Kiekens RM, Maltha JC, van ‘t Hof MA, Straatman H, KuijpersJagtman AM. Panel perception of change in facial aesthetics following orthodontic treatment in adolescents. Eur J Orthod 2008; 30:141–146. 31. Marino R, Morgan M, Kiyak A, Schwarz E, Naqvi S. Oral health in a convenience sample of Chinese older adults living in Melbourne, Australia. Int J Public Health 2012;57:383–390. 32. Du M, Petersen PE, Fan M, Bian Z, Tai B. Oral health services in PR China as evaluated by dentists and patients. Int Dent J 2000; 50:250–256. 33. Nelson S, Eggertsson H, Powell B, et al. Dental examiners consistency in applying the ICDAS criteria for a caries prevention community trial. Community Dent Health 2011;28:238–242. 34. Brocklehurst P, Ashley J, Walsh T, Tickle M. Relative performance of different dental professional groups in screening for occlusal caries. Community Dent Oral Epidemiol 2012;40: 239–246.
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