Introduction
The objective of this study was to evaluate the differences in preference between orthodontists and laypeople, judging soft tissue digital alterations of a Class II Division 1 profile of a female patient with mandibular retrognathia, produced by simulated camouflage and mandibular advancement therapy.
Methods
The profile image of a White woman with a Class II Division 1 mandibular retrognathic profile was digitally modified to produce 7 pictures: 1 baseline, 3 stepwise increase in the nasolabial angle of 113°, 121°, and 129°, and 3 stepwise increase in chin-neck length of 51 mm, 54 mm, and 57 mm. Forty-four orthodontists and 162 laypeople assessed these 7 images.
Results
The untreated baseline profile was found to be least attractive for both orthodontists and laypeople, with orthodontists scoring significantly lower than laypeople. The profiles representing mandibular advancement therapy were judged significantly better by both groups than camouflage therapy. Orthodontists preferred straighter profiles than laypeople, giving the highest-ranking to a chin-neck length of 57 mm, whereas laypeople gave the highest rank to a chin-neck length of 54 mm.
Conclusions
Orthodontists prefer straighter profiles and gave a lower ranking to the untreated Class II Division 1 female profile compared with laypeople. Orthodontists and laypeople favor mandibular advancement therapy over camouflage therapy. However, both groups seem to prefer the effect of both treatment modalities over the untreated baseline Class II Division 1 profile.
Highlights
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Orthodontists prefer a straighter profile than laypeople.
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Orthodontists judge untreated Class II Division 1 profiles as less attractive than laypeople.
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Orthodontists and laypeople appreciate the results of camouflage and mandibular advancement.
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For both groups, the most attractive nasolabial angle varied between 113° and 121°.
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For both groups, the most attractive chin-neck length varied between 54 mm and 57 mm.
Several studies have shown that an attractive individual is perceived as happier, more sociable, and more successful. , Attractive people are also treated and judged more positively , ; therefore, people want to improve their facial esthetics. When it comes to beauty, the face is the most important factor. , This is 1 of the main reasons people seek treatment by an orthodontist or an oral surgeon to improve their facial esthetics.
Treatment planning by orthodontists and oral surgeons involves a profile analysis. The most frequent malocclusion in the Netherlands is Class II Division 1 skeletal malocclusion (prevalence of 65%). To correct this malocclusion in adolescent patients, a wide range of functional or orthopedic appliances are available, which is in contrast to adult patients Class II Division 1 malocclusion. For adult patients, 2 effective treatment modalities are available. The first treatment modality is camouflage treatment therapy, with retraction of maxillary incisors after extraction of maxillary teeth resulting in overjet reduction with the posterior movement of the upper lip and an increased nasolabial angle. The second treatment modality is the surgical advancement of the mandible, often improving overjet, occlusion, dentofacial pattern, and profile esthetics by increasing the chin-neck length.
A previous study by Yüksel et al has shown that laypeople preferred mandibular advancement over camouflage therapy in profile esthetics in adults with Class II Division 1 malocclusion. Knowledge of what laypeople and orthodontists consider as attractive and whether laypeople and professionals would evaluate improvement in facial attractiveness achieved by orthodontic treatment, in the same way, could be important when considering treatment planning for adults with Class II Division 1 malocclusion. The judgment of profile esthetics by professionals vs judgment by laypeople has been repeatedly compared, but with conflicting outcomes. Therefore, it would be interesting to assess if there is a difference in preference between orthodontists and laypeople regarding the outcome of the 2 different treatment methods for adult patients with Class II Division 1 malocclusion. The outcome might be helpful in choosing between retracting maxillary teeth via extraction or headgear vs advancing the mandible with functional appliances or oral surgery when planning treatment of adults and adolescents with Class II Division 1 malocclusion.
This study aimed to investigate and compare the judgments of laypeople and orthodontists on the effect of different soft tissue alterations on the profile of a Class II Division 1 female subject with mandibular retrognathia, produced by software simulated camouflage or mandibular advancement treatment, by showing the different alterations simultaneously. In addition, to investigate and compare the amount of tolerable nasolabial angle increase and the amount of chin-neck length increase necessary for satisfactory profile improvement during treatment of adult patients with Class II Division 1 malocclusion.
Material and methods
Seven modified profile pictures of a White woman developed for a previous study were used. The woman used in this study has an untreated Class II Division 1 malocclusion with a normal face height, normal mandibular plane angle, nasolabial angle of 115.7°, chin-neck length of 51 mm, z-angle of 70°, angle of facial convexity of 21°, and a Holdaway’s profile angle of 18°. These measurements are sufficiently beyond the respective limits between Class I and Class II soft tissue profiles of 75°, 15°, and 10°. ,
In the previous study, this original photograph (untreated female profile with Class II Division 1 malocclusion) was modified with Photoshop software (Adobe, San Jose, Calif) and Dolphin Imaging software (Dolphin Imaging and Management Solutions, Chatsworth, Calif) to emphasize the effects of the 2 treatment modalities.
The scanned profile image and lateral cephalogram were both imported into software (version 11.5; Dolphin Imaging and Management Solutions). Then the images were linked to each other to standardize the profile image with the magnification of the cephalogram.
To emphasize mandibular retrusion, the profile picture was altered with Photoshop software (Adobe). To create the starting profile, profile D, the chin-neck length of the original profile was reduced from 51 mm to 45 mm, by subtracting 2 standard deviations from the norm of 57 ± 6 mm as determined by Lehman Jr, , resulting in 45 mm for this variable ( Fig 1 , D ).
To create 3 additional images simulating the treatment outcome of mandibular advancement surgery, the profile image was digitally altered using Dolphin Imaging software. The chin-neck length was increased by 1.0, 1.5, and 2.0 standard deviations resulting in chin-neck lengths of 51 mm, 54 mm, and 57 mm, respectively ( Fig 1 , E, F , and G ).
To simulate the treatment effect of camouflage treatment on the nasolabial angle, a similar procedure was performed. The original nasolabial angle of 115.7°, modified to 104.9° to achieve the starting point ( Fig 1 , D ) for further alterations according to Sinno et al. Three additional profile types were created by gradually increasing the nasolabial angle using Dolphin software. The nasolabial angle was increased by 2.0, 4.0, and 6.0 standard deviations resulting in angles of 113°, 121°, and 129° ( Fig 1 , C, B , and A ).
The original, untreated profile (D) ( Fig 1 , D ) with a chin-neck length of 45 mm and a nasolabial angle of 104.9° was the starting point for all modifications. This profile shows the most pronounced Class II Division 1 features with the largest sagittal interlabial step.
The 7 created profiles were inserted in a booklet, including a questionnaire providing information on factors that could influence the judgment of the observers. This questionnaire collected information about the age, gender, and educational level of the observers. Additional information was obtained from the orthodontists about their site of training and years of experience.
The laypersons were approached on the streets and in several parks in Amsterdam in 2016 by an undergraduate dental student. In addition, patients in waiting rooms at dental practices in Amsterdam were approached by the same dental student. The orthodontists were approached at an orthodontic congress in Soestduinen, The Netherlands, in March 2016 by another undergraduate dental student. Inclusion criteria for laypeople included the following: aged >17 years, minimum education of higher general secondary school, and primary school finished in the Netherlands. The inclusion criteria for the orthodontists was full membership of the Dutch Orthodontic Society. In total, 162 laypeople, 53% of them women and 47% men, and 44 orthodontists, evenly distributed by gender, were willing to participate. The power (α = 0.05) of this study was 0.83, which is calculated with G-Power 3.1.9.4 (Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany). This study was previously approved by the Ethics Committee (no. X14-0355).
The Figure shows the profiles printed alongside each other on an A4 page. This presentation aimed to show the participating observers a set of profiles offering clear options by placing the most pronounced Class II Division 1 profile in the center ( Fig 1 , D ) with a nasolabial angle of 104.9° and chin-neck length of 45 mm. Assuming a distinct selection between options for the observers for their preferred profile, the maximum compensation with camouflage treatment was placed on the far left ( Fig 1 , A ) with a nasolabial angle of 129° and the profile with the maximum mandibular advancement surgery on the far right ( Fig 1 , G ) with a chin-neck length of 57 mm.
Participating laypeople and orthodontists were asked to rank the profiles from 1 (most attractive) to 7 (least attractive). , A reliability test was carried out by 20 undergraduate dental students, who assessed the set of profile images with the visual analogue scale (VAS) score twice with a washout period of 2 weeks.
Statistical analysis
Friedman and Wilcoxon tests were used to analyze facial attractiveness ranking. The influence of background factors on ranking was analyzed by Kruskal-Wallis and Mann-Whitney U tests. To analyze the mean ranking difference between laypeople and orthodontists, Mann-Whitney U tests were used. The Pearson correlation test was to assess the reliability by analyzing the correlation between the ranking scores.
Results
The estimated means of the rankings calculated for the orthodontists and laypeople are shown in Table I . The orthodontists and laypeople considered profile D the least attractive. Profile G and profile F were considered the most attractive by orthodontists and laypeople, respectively. Both groups considered the results of mandibular advancement therapy (profiles E, F, and G) significantly more attractive than camouflage therapy (profiles A, B, and C). In addition, all camouflage therapy profiles (A, B, and C) were rated significantly better than the baseline (profile D). Orthodontists and laypeople scored profile A with the largest nasolabial angle, significantly more attractive than the untreated photograph (profile D) but significantly less attractive than profile B with a smaller nasolabial angle. Laypeople also scored profile A significantly less attractive than profile C with a smaller nasolabial angle. Compared with laypeople, orthodontists considered profiles resulting from mandibular advancement therapy (profiles E, F, and G) more attractive and profiles with camouflage therapy (profiles A, B, and C) less attractive. This difference was significant for profiles C, D, F, and G ( Table I ).
| Profile | Orthodontist | Laypeople | ||
|---|---|---|---|---|
| Mean | Standard deviation | Mean | Standard deviation | |
| A | (6) 5.23 B , D, E, F, G | 1.48 | (6) 4.90 B, C, D, E, F, G | 1.76 |
| B | (4) 4.55 A, D, E, F, G | 0.95 | (5) 4.40 A, D, E, F, G | 1.57 |
| C | (5) ∗ 5.09 D, E, F, G | 0.94 | (4) ∗ 4.24 A, D, E, F, G | 1.58 |
| D | (7) ∗ 6.39 A, B, C, E, F, G | 1.22 | (7) ∗ 5.65 A, B, C, E, F, G | 1.85 |
| E | (3) 3.16 A, B, C, D, F, G | 1.14 | (3) 3.22 A, B, C, D, F | 1.49 |
| F | (2) ∗ 2.00 A, B, C, D, E | 0.84 | (1) ∗ 2.70 A, B, C, D, E | 1.72 |
| G | (1) ∗ 1.59 A, B, C, D, E | 1.25 | (2) ∗ 2.90 A, B, C, D | 2.07 |
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