The European Journal of Orthodontics Advance Access published June 11, 2015 European Journal of Orthodontics, 2015, 1–9 doi:10.1093/ejo/cjv039
Original Article
Influence of premolar extractions on long-term adult facial aesthetics and apparent age Guilherme Janson, Cintia Helena Zingaretti Junqueira, Lucas Marzullo Mendes and Daniela Gamba Garib Department of Orthodontics, Bauru Dental School, University of São Paulo, Bauru, São Paulo, Brazil Correspondence to: Cintia Helena Zingaretti Junqueira, Department of Orthodontics, Bauru Dental School, University of São Paulo, Alameda Octávio Pinheiro Brisolla 9–75, Bauru, SP 17012–901, Brazil. E-mail: [email protected]
Summary
Introduction Nowadays facial aesthetics is strongly valued, sometimes even more than occlusion and functions, and consists in one of the primary goals of orthodontic treatment. Fuller lips and slightly protrusive profile are being preferred, especially in women (1, 2). Several studies concluded that smaller noses may also be desired (3–7). Retruded lips may emphasize the size of nose and chin, making them look bigger (6, 8). Concerns with the ‘dished in’ profile has prevented some orthodontists from choosing treatment plans based on premolar extractions (9). Speculation that extractions may harm facial aesthetics is based on the reduction of dental volume available for lip support. Even many years after they have been introduced in the orthodontic scenario, extraction effects are still being studied regarding efficiency, occlusal outcomes, stability, and post-treatment aesthetics (10–15).
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Objectives: This study aimed to assess whether non-extraction, two-premolars and four-premolars extraction Class II treatment protocols are different regarding long-term facial aesthetics, age appearance, and soft-tissue measures. Methods: Frontal and lateral photographs of 63 full Class II division 1 patients, treated at least 8 years before, were evaluated by 83 laypeople and 76 orthodontists, who assigned to each one’s attractiveness scores from 1 to 10, and opined about their apparent ages. Patients were divided in three groups: XP0 (non-extraction, n = 20; 30.77 years, 15.63 years post-treatment), XP2 (twopremolars extractions, n = 25; 30.99 years, 15.68 years post-treatment), and XP4 (four-premolar extractions, n = 18; 32.80 years, 18.01 years post-treatment), that were matched by gender, posttreatment occlusal and soft-tissue outcomes, age, and post-treatment time. Soft-tissue measures were obtained with Dolphin Imaging 11.5 software. Results: Two-way analysis of variance revealed that attractiveness and apparent age were not affected by treatment protocols, but laypeople were slightly more critical then orthodontists. Analysis of variance showed more vertical facial pattern in XP4 group. Pearson correlation test revealed no influence of soft-tissue measures on sample’s attractiveness. Conclusions: Treatment of full Class II division 1 malocclusion with and without extractions did not influence facial attractiveness, age appearance, and overall soft-tissue measures in the long-term.
In Orthodontics, premolar extraction may be indicated for severe crowding, excess dentoalveolar protrusion and skeletal/inter-arch discrepancies camouflage (14). Several authors have evaluated the effects of extractions on patient’s faces (14, 16–20). However, most of them only compare cephalometric results obtained with and without extractions, not considering the actual judgment of facial aesthetics (16–20), neither the long-term effects (16–20). More important than cephalometric final values are the overall facial attractiveness provided by treatment. After the end of growth, there are still continuous changes in the nose and chin, increasing lips retrusion (21). Because protruded lips are related to attractive faces (2), relative increases of other structures negatively influence profile attractiveness. As these soft tissue changes somehow contribute to an expected decrease in attractiveness, concerns
© The Author 2015. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: [email protected]
1
2 with the soft tissue effects of premolar removal may increase with time. But what happens in the long-term? Is post-retention facial aesthetics the same in patients treated with and without premolar extractions? Class II malocclusion treatment may involve two-maxillary premolar extractions generally when there is no crowding or cephalometric discrepancy in the mandibular arch, or two maxillary and two mandibular premolar extractions, primarily to correct crowding in the mandibular arch, a cephalometric discrepancy, or a combination of both, in growing patients (22). To our knowledge, no study has evaluated the long-term influence of premolar extractions on Class II division 1 malocclusions, exclusively. This context led us to assess if non-extraction, two-premolar extraction and four-premolar extraction treatment protocols of Class II division 1 malocclusion are different regarding facial aesthetics and the apparent age in the long-term.
Material and methods This study was approved by the Research Ethical Committee of Bauru Dental School, University of São Paulo (number 032/2011). Informed consents were obtained from patients and raters.
Sample
Groups comparability The three groups had to present similar occlusal and cephalometric orthodontic treatment outcomes. The post-treatment occlusal outcomes were evaluated using the objective grading system (OGS) index of the American Board of Orthodontics (27, 28) and specific soft tissue variables. The cephalometric comparability was evaluated with the post-treatment cephalograms. The post-treatment lateral headfilms, obtained in centric occlusion with passive lip posture, were scanned and stored on a personal computer and analysed with Dolphin Imaging 11.5 Software (Dolphin Imaging and Management Solutions, Chatsworth, California, USA) (29). Because the headfilms had been taken with different X-ray machines, the enlargement factors, which ranged from 6.0% to 9.8%, were corrected with the cephalometric software. The variables obtained on the final lateral cephalograms are displayed in Table 1. To check intergroup comparability regarding occlusal stability, the long-term overjets were clinically measured and well matched.
Clinical photographs Long-term post-treatment lateral and frontal extra-oral photographs were obtained in a standardized position. Subjects were oriented to stay in natural head position (NHP)—a reproducible, upright, and natural posture, with the visual axis horizontally oriented, teeth in centric occlusion, lips at rest. They were asked to not to touch the wall with their back, to keep arms relaxed and feet slightly apart, looking at their eyes height (30). Any accessories like earrings, necklaces, or piercings were removed. Long hairs were homogeneously tied. All photographs were taken with a digital Nikon D90 SLR camera (Nikon Corporation, Tokyo, Japan) coupled to a Sigma 105mm 2.8 DG MACRO lens and a Sigma EM-140 DG NA-iTTL ring flash (Sigma Corporation, Kanagawa, Japan). These photographs were used for the aesthetic and apparent age judgment. The lateral photographs were also used to obtain cephalometric soft tissue variables (31). The soft-tissue variables were obtained with Dolphin Imaging Software, which are also listed on Table 1. A known distance of each subject was inserted into the software to calibrate each photograph to its actual size. The planes and lines used are illustrated in Figure 1.
Aesthetic and apparent age judgment Using Adobe Photoshop CS6 (Adobe Systems Incorporated, version 13.0, San Jose, CA, USA), the Frankfurt plane was checked to be horizontally oriented on the lateral images and the midsagittal plane was checked to be vertically oriented in the frontal images. Any distractors such as spots, pimples, scars, or tattoos were removed. After that, all images were converted to grey scale (Figure 2). The frontal and lateral photographs of each patient were combined to consist in a pair of images. Therefore, considering that each patient had longterm post-treatment stage lateral and frontal photographs, there was a total of 126 images, distributed in 63 pairs of images. Based on a previous methodology (24), potential raters were invited by e-mail to access the website created for this research, with provided personal usernames and passwords. Raters registered date of birth, gender, area of formal education and higher reached level. In order to calibrate themselves regarding the sample, raters were instructed to first evaluate the Gallery section, where all 63 patients could be simultaneously observed (Figure 3). The pairs of photographs were automatically randomized, in each access. There was no time restriction for each evaluation, until the final evaluation was submitted.
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Patient sample size calculation was based on an alpha significance level of 0.05 and a beta of 0.2, to achieve a power of 80%. To detect a difference of 1.25 mm in the distance from the upper lip to H line with an estimated standard deviation of 1.3 mm (23), each group should have at least 18 patients. The number of raters were similarly calculated to detect a mean difference of 0.5 point in the rating scores, with an estimated standard deviation of 1.06 point (24), and was found to be of 72 raters. Sixty-three orthodontically treated phenotypically mediterranean patients were selected according to the following inclusion criteria: 1. initial full cusp Class II division 1 malocclusion, 2. adult—minimum of 21 years of age (25); 3. availability of orthodontic records; 4. no anterior tooth loss in the long-term period; and 5. frontal and lateral extra-oral photographs, taken at a minimum of 8 years after treatment. Patients were divided into three groups according to the treatment protocol: non-extraction (n = 20), two-maxillary premolar extractions (n = 25) and four-premolar extractions (n = 18). Orthodontic mechanics included fixed edgewise appliances, with 0.022-inch × 0.028-inch conventional brackets and an usual wire sequence characterized by initial 0.015 Twist-Flex or 0.016 Nitinol, followed by 0.016-, 0.018-, 0.020-, and 0.019-inch × 0.025-inch or 0.018-inch × 0.025-inch stainless steel archwires (all from 3M Unitek, Monrovia, California, USA). Deepbites were corrected with accentuated and reversed curve of Spee (26). In the extraction groups the anterior teeth were retracted en masse with rectangular archwires for overjet and Class II canine correction. Extraoral headgear was used to correct the Class II antero-posterior relationship in the non-extraction and in the four-premolar extraction groups; in the non-extraction group, six patients used functional appliances and three patients used them associated to extraoral headgear. In the two-premolar extraction group, extraoral headgear was used to reinforce anchorage and maintain the Class II molar relationship. When necessary, Class II elastics were used to help obtain a Class I molar relationship, in the non-extraction and in the four-premolar extraction groups, and to help maintain a Class II molar relationship in the two-premolar extraction group. A maxillary Hawley plate was recommended to be used full-time (except during meals) for 6 months and at night, for additional 6 months. A mandibular canine-to-canine fixed retainer was installed to be used for a mean period of 3 years.
European Journal of Orthodontics, 2015
3
G. Janson et al. Table 1. Soft-tissue measures obtained from the long-term lateral photographs and from the post-treatment cephalograms. Field
Variable
Landmarks and lines
Abbreviation
Obtained on
Soft-tissue measures
Frontonasal angle (°) Nasal proeminence (°) Nasal length (mm) Tip of nose—H line (mm) Nasolabial angle (°) Mentolabial angle (°) Mentocervical line (mm) Cervicofacial angle (°) Facial angle (°) Lower lip-H line (mm) Upper lip-E line (mm) Lower lip-E line (mm) Upper lip-S line (mm) Lower lip-S line(mm) Upper lip-Pg’Sn line (mm) Lower lip-Pg’Sn line (mm) Upper lip-Pg’N’ line (mm) Lower lip-Pg’N’ line (mm) Upper lip length (mm) Lower lip length (mm) Lower anterior face height (mm) Post-treatment overjet Long-term overjet
G’N’Prn PrnN’Sn Sn-Prn Prn-Pg’Ls ColSnLs LiB’Pg’ C’-Me’ SnPg’Me’C’ SnPg’G’ Li-Pg’Sn Ls-Pg’Prn Li-Pg’Prn Ls-Pg’Cm Li-Pg’Cm Ls-Pg’Sn Li-Pg’Sn Ls-Pg’N Li-Pg’N’ Sn-Stms Sn-Stmi Sn-Me’ Dolphin defined
FNA NP NL H-nose NLA MLA MCL CFA FA Li-H Ls-E Li-E Ls-S Li-S Ls-Pg’Sn Li-Pg’Sn Ls-Pg’N’ Li-Pg’N’ ULL LLL LAFH — —
LTP LTP LTP BOTH BOTH LTP LTP LTP LTP BOTH BOTH BOTH BOTH BOTH BOTH BOTH LTP LTP LTP LTP LTP PTC CLN
Distance from lips to aesthetic lines
Growth pattern
Dental measure
The raters used a 10-point numerical scale, where 1 represented ‘the most unattractive face’ and 10 represented ‘the most attractive face’. They were also asked to evaluate each patient’s apparent age (Figure 4). The difference between each apparent and actual age was then calculated. When the apparent was greater than the actual age, the difference between them was positive, which meant that the patient appeared to be older than he/she actually was and vice-versa. An icon in each page could drive the rater to the Gallery section to revise the scores, as necessary, allowing intra-rater calibration in evaluating the faces.
Raters The aesthetic evaluation was carried out by 76 orthodontists from a national Orthodontic Association (39 post-graduate orthodontic students and 39 specialists) and a panel of 83 lay people (4 physicians, 7 from other biomedical areas, 18 professionals from exact sciences, 39 professionals from human sciences, and 15 described themselves as not fitting in none of the options).
Error study Two weeks after the first evaluation, 23 randomly selected photographs were retraced by the same examiner (Cintia Helena Zingaretti Junqueira). Twenty-five orthodontists and 28 laypeople re-evaluated the same subjects in a different arrangement. Random errors were calculated according to Dahlberg’s formula (S2 = Σd2/2n) (32), where S2 is the error variance and d is the difference between two determinations of the same variable. Systematic errors were estimated with dependent t-tests, for P
Original Article
Influence of premolar extractions on long-term adult facial aesthetics and apparent age Guilherme Janson, Cintia Helena Zingaretti Junqueira, Lucas Marzullo Mendes and Daniela Gamba Garib Department of Orthodontics, Bauru Dental School, University of São Paulo, Bauru, São Paulo, Brazil Correspondence to: Cintia Helena Zingaretti Junqueira, Department of Orthodontics, Bauru Dental School, University of São Paulo, Alameda Octávio Pinheiro Brisolla 9–75, Bauru, SP 17012–901, Brazil. E-mail: [email protected]
Summary
Introduction Nowadays facial aesthetics is strongly valued, sometimes even more than occlusion and functions, and consists in one of the primary goals of orthodontic treatment. Fuller lips and slightly protrusive profile are being preferred, especially in women (1, 2). Several studies concluded that smaller noses may also be desired (3–7). Retruded lips may emphasize the size of nose and chin, making them look bigger (6, 8). Concerns with the ‘dished in’ profile has prevented some orthodontists from choosing treatment plans based on premolar extractions (9). Speculation that extractions may harm facial aesthetics is based on the reduction of dental volume available for lip support. Even many years after they have been introduced in the orthodontic scenario, extraction effects are still being studied regarding efficiency, occlusal outcomes, stability, and post-treatment aesthetics (10–15).
Downloaded from by guest on June 18, 2015
Objectives: This study aimed to assess whether non-extraction, two-premolars and four-premolars extraction Class II treatment protocols are different regarding long-term facial aesthetics, age appearance, and soft-tissue measures. Methods: Frontal and lateral photographs of 63 full Class II division 1 patients, treated at least 8 years before, were evaluated by 83 laypeople and 76 orthodontists, who assigned to each one’s attractiveness scores from 1 to 10, and opined about their apparent ages. Patients were divided in three groups: XP0 (non-extraction, n = 20; 30.77 years, 15.63 years post-treatment), XP2 (twopremolars extractions, n = 25; 30.99 years, 15.68 years post-treatment), and XP4 (four-premolar extractions, n = 18; 32.80 years, 18.01 years post-treatment), that were matched by gender, posttreatment occlusal and soft-tissue outcomes, age, and post-treatment time. Soft-tissue measures were obtained with Dolphin Imaging 11.5 software. Results: Two-way analysis of variance revealed that attractiveness and apparent age were not affected by treatment protocols, but laypeople were slightly more critical then orthodontists. Analysis of variance showed more vertical facial pattern in XP4 group. Pearson correlation test revealed no influence of soft-tissue measures on sample’s attractiveness. Conclusions: Treatment of full Class II division 1 malocclusion with and without extractions did not influence facial attractiveness, age appearance, and overall soft-tissue measures in the long-term.
In Orthodontics, premolar extraction may be indicated for severe crowding, excess dentoalveolar protrusion and skeletal/inter-arch discrepancies camouflage (14). Several authors have evaluated the effects of extractions on patient’s faces (14, 16–20). However, most of them only compare cephalometric results obtained with and without extractions, not considering the actual judgment of facial aesthetics (16–20), neither the long-term effects (16–20). More important than cephalometric final values are the overall facial attractiveness provided by treatment. After the end of growth, there are still continuous changes in the nose and chin, increasing lips retrusion (21). Because protruded lips are related to attractive faces (2), relative increases of other structures negatively influence profile attractiveness. As these soft tissue changes somehow contribute to an expected decrease in attractiveness, concerns
© The Author 2015. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: [email protected]
1
2 with the soft tissue effects of premolar removal may increase with time. But what happens in the long-term? Is post-retention facial aesthetics the same in patients treated with and without premolar extractions? Class II malocclusion treatment may involve two-maxillary premolar extractions generally when there is no crowding or cephalometric discrepancy in the mandibular arch, or two maxillary and two mandibular premolar extractions, primarily to correct crowding in the mandibular arch, a cephalometric discrepancy, or a combination of both, in growing patients (22). To our knowledge, no study has evaluated the long-term influence of premolar extractions on Class II division 1 malocclusions, exclusively. This context led us to assess if non-extraction, two-premolar extraction and four-premolar extraction treatment protocols of Class II division 1 malocclusion are different regarding facial aesthetics and the apparent age in the long-term.
Material and methods This study was approved by the Research Ethical Committee of Bauru Dental School, University of São Paulo (number 032/2011). Informed consents were obtained from patients and raters.
Sample
Groups comparability The three groups had to present similar occlusal and cephalometric orthodontic treatment outcomes. The post-treatment occlusal outcomes were evaluated using the objective grading system (OGS) index of the American Board of Orthodontics (27, 28) and specific soft tissue variables. The cephalometric comparability was evaluated with the post-treatment cephalograms. The post-treatment lateral headfilms, obtained in centric occlusion with passive lip posture, were scanned and stored on a personal computer and analysed with Dolphin Imaging 11.5 Software (Dolphin Imaging and Management Solutions, Chatsworth, California, USA) (29). Because the headfilms had been taken with different X-ray machines, the enlargement factors, which ranged from 6.0% to 9.8%, were corrected with the cephalometric software. The variables obtained on the final lateral cephalograms are displayed in Table 1. To check intergroup comparability regarding occlusal stability, the long-term overjets were clinically measured and well matched.
Clinical photographs Long-term post-treatment lateral and frontal extra-oral photographs were obtained in a standardized position. Subjects were oriented to stay in natural head position (NHP)—a reproducible, upright, and natural posture, with the visual axis horizontally oriented, teeth in centric occlusion, lips at rest. They were asked to not to touch the wall with their back, to keep arms relaxed and feet slightly apart, looking at their eyes height (30). Any accessories like earrings, necklaces, or piercings were removed. Long hairs were homogeneously tied. All photographs were taken with a digital Nikon D90 SLR camera (Nikon Corporation, Tokyo, Japan) coupled to a Sigma 105mm 2.8 DG MACRO lens and a Sigma EM-140 DG NA-iTTL ring flash (Sigma Corporation, Kanagawa, Japan). These photographs were used for the aesthetic and apparent age judgment. The lateral photographs were also used to obtain cephalometric soft tissue variables (31). The soft-tissue variables were obtained with Dolphin Imaging Software, which are also listed on Table 1. A known distance of each subject was inserted into the software to calibrate each photograph to its actual size. The planes and lines used are illustrated in Figure 1.
Aesthetic and apparent age judgment Using Adobe Photoshop CS6 (Adobe Systems Incorporated, version 13.0, San Jose, CA, USA), the Frankfurt plane was checked to be horizontally oriented on the lateral images and the midsagittal plane was checked to be vertically oriented in the frontal images. Any distractors such as spots, pimples, scars, or tattoos were removed. After that, all images were converted to grey scale (Figure 2). The frontal and lateral photographs of each patient were combined to consist in a pair of images. Therefore, considering that each patient had longterm post-treatment stage lateral and frontal photographs, there was a total of 126 images, distributed in 63 pairs of images. Based on a previous methodology (24), potential raters were invited by e-mail to access the website created for this research, with provided personal usernames and passwords. Raters registered date of birth, gender, area of formal education and higher reached level. In order to calibrate themselves regarding the sample, raters were instructed to first evaluate the Gallery section, where all 63 patients could be simultaneously observed (Figure 3). The pairs of photographs were automatically randomized, in each access. There was no time restriction for each evaluation, until the final evaluation was submitted.
Downloaded from by guest on June 18, 2015
Patient sample size calculation was based on an alpha significance level of 0.05 and a beta of 0.2, to achieve a power of 80%. To detect a difference of 1.25 mm in the distance from the upper lip to H line with an estimated standard deviation of 1.3 mm (23), each group should have at least 18 patients. The number of raters were similarly calculated to detect a mean difference of 0.5 point in the rating scores, with an estimated standard deviation of 1.06 point (24), and was found to be of 72 raters. Sixty-three orthodontically treated phenotypically mediterranean patients were selected according to the following inclusion criteria: 1. initial full cusp Class II division 1 malocclusion, 2. adult—minimum of 21 years of age (25); 3. availability of orthodontic records; 4. no anterior tooth loss in the long-term period; and 5. frontal and lateral extra-oral photographs, taken at a minimum of 8 years after treatment. Patients were divided into three groups according to the treatment protocol: non-extraction (n = 20), two-maxillary premolar extractions (n = 25) and four-premolar extractions (n = 18). Orthodontic mechanics included fixed edgewise appliances, with 0.022-inch × 0.028-inch conventional brackets and an usual wire sequence characterized by initial 0.015 Twist-Flex or 0.016 Nitinol, followed by 0.016-, 0.018-, 0.020-, and 0.019-inch × 0.025-inch or 0.018-inch × 0.025-inch stainless steel archwires (all from 3M Unitek, Monrovia, California, USA). Deepbites were corrected with accentuated and reversed curve of Spee (26). In the extraction groups the anterior teeth were retracted en masse with rectangular archwires for overjet and Class II canine correction. Extraoral headgear was used to correct the Class II antero-posterior relationship in the non-extraction and in the four-premolar extraction groups; in the non-extraction group, six patients used functional appliances and three patients used them associated to extraoral headgear. In the two-premolar extraction group, extraoral headgear was used to reinforce anchorage and maintain the Class II molar relationship. When necessary, Class II elastics were used to help obtain a Class I molar relationship, in the non-extraction and in the four-premolar extraction groups, and to help maintain a Class II molar relationship in the two-premolar extraction group. A maxillary Hawley plate was recommended to be used full-time (except during meals) for 6 months and at night, for additional 6 months. A mandibular canine-to-canine fixed retainer was installed to be used for a mean period of 3 years.
European Journal of Orthodontics, 2015
3
G. Janson et al. Table 1. Soft-tissue measures obtained from the long-term lateral photographs and from the post-treatment cephalograms. Field
Variable
Landmarks and lines
Abbreviation
Obtained on
Soft-tissue measures
Frontonasal angle (°) Nasal proeminence (°) Nasal length (mm) Tip of nose—H line (mm) Nasolabial angle (°) Mentolabial angle (°) Mentocervical line (mm) Cervicofacial angle (°) Facial angle (°) Lower lip-H line (mm) Upper lip-E line (mm) Lower lip-E line (mm) Upper lip-S line (mm) Lower lip-S line(mm) Upper lip-Pg’Sn line (mm) Lower lip-Pg’Sn line (mm) Upper lip-Pg’N’ line (mm) Lower lip-Pg’N’ line (mm) Upper lip length (mm) Lower lip length (mm) Lower anterior face height (mm) Post-treatment overjet Long-term overjet
G’N’Prn PrnN’Sn Sn-Prn Prn-Pg’Ls ColSnLs LiB’Pg’ C’-Me’ SnPg’Me’C’ SnPg’G’ Li-Pg’Sn Ls-Pg’Prn Li-Pg’Prn Ls-Pg’Cm Li-Pg’Cm Ls-Pg’Sn Li-Pg’Sn Ls-Pg’N Li-Pg’N’ Sn-Stms Sn-Stmi Sn-Me’ Dolphin defined
FNA NP NL H-nose NLA MLA MCL CFA FA Li-H Ls-E Li-E Ls-S Li-S Ls-Pg’Sn Li-Pg’Sn Ls-Pg’N’ Li-Pg’N’ ULL LLL LAFH — —
LTP LTP LTP BOTH BOTH LTP LTP LTP LTP BOTH BOTH BOTH BOTH BOTH BOTH BOTH LTP LTP LTP LTP LTP PTC CLN
Distance from lips to aesthetic lines
Growth pattern
Dental measure
The raters used a 10-point numerical scale, where 1 represented ‘the most unattractive face’ and 10 represented ‘the most attractive face’. They were also asked to evaluate each patient’s apparent age (Figure 4). The difference between each apparent and actual age was then calculated. When the apparent was greater than the actual age, the difference between them was positive, which meant that the patient appeared to be older than he/she actually was and vice-versa. An icon in each page could drive the rater to the Gallery section to revise the scores, as necessary, allowing intra-rater calibration in evaluating the faces.
Raters The aesthetic evaluation was carried out by 76 orthodontists from a national Orthodontic Association (39 post-graduate orthodontic students and 39 specialists) and a panel of 83 lay people (4 physicians, 7 from other biomedical areas, 18 professionals from exact sciences, 39 professionals from human sciences, and 15 described themselves as not fitting in none of the options).
Error study Two weeks after the first evaluation, 23 randomly selected photographs were retraced by the same examiner (Cintia Helena Zingaretti Junqueira). Twenty-five orthodontists and 28 laypeople re-evaluated the same subjects in a different arrangement. Random errors were calculated according to Dahlberg’s formula (S2 = Σd2/2n) (32), where S2 is the error variance and d is the difference between two determinations of the same variable. Systematic errors were estimated with dependent t-tests, for P
