ORIGINAL ARTICLE

Influence of orthodontic bracket

prescription on smile attractiveness
in patients with different sagittal
skeletal patterns: A 3-dimensional
cross-sectional study
Stephanie Kreichati, Adib Kassis, Rami Falah Aboujaoude, and Roula Akl
Beirut, Lebanon

Introduction: The objective of this study was to evaluate the influence of orthodontic bracket prescription on
smile attractiveness. Methods: Three women were chosen according to their sagittal skeletal pattern: skel-
etal Class I, II, or III malocclusion. For each, 3 smiling pictures were taken in frontal, oblique, and lateral
views. The maxillary arch was then scanned, and a 3-dimensional digital model was constructed on the
OrthoAnalyzer software. The information of 3 orthodontic prescriptions, namely Roth, MBT, and Ricketts,
was simulated after the virtual placement of orthodontic brackets on 10 maxillary teeth. The simulations
were then superimposed on the smile photographs in the 3 views, creating a total of 27 images. Groups
of orthodontists, dentists, and laypeople rated the attractiveness of each smile using the visual analog
scale. Results: This study included 167 evaluators: 54 orthodontists, 54 dentists, and 59 laypersons. In
terms of orthodontic prescription, MBT esthetic scores were 4% lower than Roth scores (P \0.001), and
Ricketts scores were 13.6% lower than Roth scores (P \0.001). In terms of skeletal pattern, Class II and
III scores were 15.0% and 16.4% lower than Class I scores, respectively (P \0.001). Regarding the smiling
view, oblique view scores were 3.1% lower than frontal view scores (P 5 0.031), whereas lateral view scores
were 8.4% lower than frontal view scores (P \0.001). In contrast to gender and age, the specialty of the eval-
uators significantly affected the esthetic rating of the smiles. Conclusions: The attractiveness of a smile is
affected by the prescription of the brackets. The Roth prescription tends to obtain the most favorable esthetic
scores, especially in sagittal smiling images. Profile smiles with excessively proclined incisors are consid-
ered unattractive. Different views of the same smile do not get similar esthetic scores because sagittal views
are rated the most severely. (Am J Orthod Dentofacial Orthop 2024;165:434-46)

A
n esthetically pleasing smile is the key feature of both the 3-dimensional (3D) control of occlusion and
facial appearance. Dentoalveolar esthetics re- the perception of the smile in profile and frontal
mains an essential aspect of esthetic dentistry, views.7-9 The labiolingual inclination of the posterior
particularly in the segment extending between the teeth also plays an important role in the esthetics of a
maxillary first premolars, also known as the esthetic smile.10,11
zone.1,2 The anteroposterior inclination of the anterior In 1972, Andrews described the 6 keys to normal oc-
teeth,3-6 as well as their mesiodistal orientation, affect clusion, in which he presented the notion of tooth incli-
nation and set ideal standards on the matter.12 He then
From the Department of Orthodontics and Dentofacial Orthopedics, Faculty of
Dental Medicine, Saint Joseph University of Beirut, Beirut, Lebanon.
introduced a system of preinformed orthodontic
All authors have completed and submitted the ICMJE Form for Disclosure of Po- brackets in which he incorporated first-, second-, and
tential Conflicts of Interest, and none were reported. third-order information.13 His innovations inspired
Address correspondence to: Stephanie Kreichati, Department of Orthodontics
and Dentofacial Orthopedics, Faculty of Dental Medicine, Saint Joseph University many orthodontists, such as Roth, Ricketts, McLaughlin,
of Beirut, Beirut 1107 2180, Lebanon; e-mail, stephkreichati@gmail.com. Bennett, and Trevisi, who later developed their tech-
Submitted, June 2023; revised and accepted, October 2023. niques and prescriptions.14-18
0889-5406/$36.00
Ó 2023 by the American Association of Orthodontists. All rights reserved.
In clinical practice, patients often present with
https://doi.org/10.1016/j.ajodo.2023.10.018 sagittal skeletal discrepancies. In certain situations,
434
Kreichati et al 435

dentoalveolar compensations should be applied to over- and 1 patient with compensated skeletal Class III maloc-
come these skeletal disharmonies.11,19 Nowadays, the clusion. Their selection was also based on the following
main objective of orthodontic treatment should be to criteria: adult patient having signed the informed con-
improve dentofacial esthetics rather than to focus exclu- sent with a normodivergent facial pattern, a centered
sively on occlusal relationships. It would thus be inter- dental midline, Class I dental relationships, a gingival
esting to define the esthetic limits of dental exposure at smile \3 mm, a healthy periodontium, a
compensation in patients with maxillomandibular dis- maxillary dental arch not presenting crowding or irregu-
crepancies, especially in the sagittal direction. larities, decayed or fractured teeth, temporary teeth,
Former research on dentoalveolar esthetics has dental agenesis or extracted teeth, anomalies of shape
mainly focused on modifications in the position of a sin- or size, and without a history of orthognathic surgery.
gle tooth or a limited number of teeth.3-7,11,19,20 More- Lateral cephalometric examinations were used to diag-
over, these modifications consist mostly of digital nose the sagittal skeletal pattern, according to the
alterations on photographic images and a bidimensional Tweed and Wits analyses: skeletal Class I malocclusion
plane. In reality, all the bonded teeth are positioned in a was confirmed by the presence of an ANB angle between
3D spatial configuration depending on the information 1 and 5 and an AoBo measurement of 0 mm for
introduced in the orthodontic brackets, which can then women, skeletal Class II malocclusion presented an
influence the esthetic perception of a smile. In this sense, ANB angle superior to 5 and an AoBo measurement su-
the OrthoAnalyzer software (3Shape, Copenhagen, perior to 2 mm for women, and skeletal Class III maloc-
Denmark) offers the advantage of containing a library clusion presented an ANB angle inferior to 1 and an
with different orthodontic bracket systems and prescrip- AoBo measurement inferior to 2 mm for women.24,25
tions that can be used to simulate the final 3D position For each patient, 3 points were marked on the
of the teeth after orthodontic treatment.21 gingiva with an indelible marker: point A, located be-
To our knowledge, no study has evaluated the effect tween the right canine and lateral incisor; point B,
of various bracket prescriptions on the appearance of a located between the right central and lateral incisors;
smile, especially when considering the sagittal skeletal and point C, located between the left central and lateral
classification. Therefore, the main objective of this study incisors. Three smiling photographs were taken with the
was to evaluate the influence of orthodontic bracket pre- subject’s head horizontal, at a distance of 1.5 m from the
scription on the evaluation of the attractiveness of a camera (Canon EOS 800D; Ota City, Tokyo, Japan), at a
smile while using the OrthoAnalyzer software. speed of 8 milliseconds with flash and an aperture of F8,
Clinically, it is essential for a practitioner to appre- under standard lighting conditions, with a black back-
ciate a smile from multiple perspectives, including fron- ground, and in 3 different views: anterior 0 smile, obli-
tal, oblique, and sagittal views.7,22,23 Similarly, it appears que 45 smile, and lateral 90 smile (Fig 1).
to be essential to extend our esthetic research in these 3 The maxillary arch was then directly scanned using
dimensions to reach valid conclusions. The secondary 3Shape Trios (3Shape) to preserve the clarity of the
objectives of this study were to evaluate the influence marked points, and the optical impression was trans-
of orthodontic prescription on smile attractiveness ac- ferred to the OrthoAnalyzer software in which a 3D dig-
cording to the sagittal skeletal pattern, to evaluate the ital maxillary model was constructed. The model was
effect of the specialty and gender of the evaluators on segmented, and the “Bracket Placement” option was
the perception of smile esthetics, and to assess whether chosen. FA point, being the center of the clinical crown
the frontal, oblique and sagittal views of the same smile as described by Andrews, was confirmed for each tooth,
obtain similar esthetic scores. and the most appropriate arch shape was selected16 (Fig
2). The virtual brackets with 0.022 3 0.028-in dimen-
sions were chosen from the OrthoAnalyzer software li-
MATERIAL AND METHODS
brary and then ideally positioned on 10 maxillary
This cross-sectional study has received the agreement teeth, from the second right premolar to the second
of the research ethics committee of the Saint Joseph left premolar, with respect to the dental axis and the
University of Beirut (USJ-2022-203). FA point. A rectangular archwire with a section of
The following protocol was applied. Three female pa- 0.019 3 0.025-in was selected, then the information
tients, previously treated at the Dental Care Center of the of the virtual brackets was expressed for 3 prescription
Saint Joseph University of Beirut, were chosen according types: Roth (U/L 5 3 5 Victory Series, Roth 0.022-in;
to their sagittal skeletal pattern: 1 patient with a skeletal 3M, Unitek, Monrovia, Calif), MBT (U/L 5 3 5 Victory
Class I malocclusion with normal incisors relationships, 1 Series, MBT 0.022-in; 3M Unitek) and Ricketts (U/L 5
patient with compensated skeletal Class II malocclusion, 3 5 APC Flash-Free SmartClip, Ricketts 0.022-in;

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436 Kreichati et al

Fig 1. Three points (A, B, and C) are marked on the gingiva, and the smiling photographs are taken in 3
views: frontal, lateral, and oblique. Point A, between the right canine and lateral incisors; Point B, be-
tween the right central and lateral incisors; Point C, between the left central and lateral incisors.

Fig 2. A, Bracket Placement option is selected; B, Maxillary model is segmented; C, Dental cuts are
defined; D, Dental axes are defined; E, Rotation centers are defined; F, Arch shape is selected.

3M Unitek) (Table I). The simulated position of the Adobe Systems Inc, San Jose, Calif), and the initial
maxillary teeth was then captured in 3 views: 0 , 45 , maxillary teeth were removed from the images. To
and 90 (Fig 3). reduce bias that could be encountered during the judg-
To fabricate the smile images to be evaluated, the ment, the photographs were subsequently cropped,
original photographs were first uploaded to the Adobe maintaining a frame extending from the cutaneous sub-
Photoshop software (version 8.0, Adobe Photoshop CS; orbital point to below cutaneous point B.26 Second, the

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Kreichati et al 437

was 165. The sample was then divided into 3 groups ac-
Table I. Torque (third order) and mesiodistal angula-
cording to their specialty: orthodontists, dentists, and
tion (second order) values incorporated in the different
laypeople, and into 2 groups according to their gender.
brackets for the maxillary arch according to 3 prescrip-
The dentists and orthodontists have completed their
tions: Roth, MBT, and Ricketts16
professional training. The laypeople consisted of adults
Teeth no. 11/21 12/22 13/23 14/24 15/25 aged .18 years and unrelated to dentistry.
Roth
Third order ( ) 12 8 2 7 7 Statistical analysis
Second order ( ) 5 9 13 0 0
MBT Data analysis was performed using SPSS software
Third order ( ) 17 10 7 7 7 (version 26; IBM, Armonk, NY). Descriptive statistics of
Second order ( ) 5 9 11 2 2 quantitative and qualitative variables were presented
Ricketts
respectively as mean 6 standard deviation and fre-
Third order ( ) 22 14 7 0 0
Second order ( ) 0 8 5 0 0 quencies. Intraobserver reproducibility was assessed us-
ing the estimation of the intraclass correlation
11/21, Maxillary central incisors; 12/22, Maxillary lateral incisors; coefficient and its 95% confidence interval for a 2-
13/23, Maxillary canines; 14/24, Maxillary first premolars; 15/25,
Maxillary second premolars.
factor mixed-effects model, a single evaluator, and ab-
solute agreement (\0.50, poor; 0.50-0.75, fair; 0.75-
0.90, good; .0.9, excellent reproducibility).
digital scans were uploaded to the OrthoAnalyzer soft- For the comparison of 3 dependent means, the
ware. The options “2D measurements” and “Image Over- repeated measures ANOVA was used, followed by
lay” were successively selected, and the edited Bonferroni’s post-hoc test for multiple comparisons.
photographs of the patient were uploaded. The option The homogeneity of the variances was verified using
“Scale 1:1” was then selected to obtain a real size ratio Levene’s test. For the comparison of 2 independent
of the teeth. The previously marked points served as a means, the Student t test was used, and for the com-
reference for superimposing the digital model on the up- parison of 3 independent means, the following statis-
loaded photograph. The superimposition of the sagittal tical tests were used: Welch’s ANOVA followed by
and oblique views was done on the A and B points, Games-Howell’s post-hoc test when the hypothesis
and the superimposition of the frontal view was done of the homogeneity of variances was rejected and uni-
on points A and C. Finally, the obtained superimposi- variate ANOVA when variances were homogeneous,
tions were uploaded in the Adobe Photoshop software, followed by Bonferroni adjustment for multiple com-
and the Photoshop expert modified the texture and color parisons. A generalized estimating equation (GEE)
of the digital teeth into a more realist appearance. This model was finally carried out to determine the predic-
process was repeated for the 3 patients until a total of tors of the variation of esthetic scores; adjusted odds
27 smile images were obtained (Figs 4-6). ratios and their 95% confidence intervals were calcu-
For data acquisition, a web-based “Google Forms” lated and reported. The significance level was set at
survey was used. For the assessment of the scoring reli- 5%, and all tests were 2-sided.
ability, 3 images were duplicated in the survey. The vi-
sual analog scale (0-10) was used to rate the different RESULTS
images (0, a very unattractive smile; 10, a very attractive This study included 167 evaluators, with a mean age
smile).3 No specific information related to the images of 38.47 6 14.15 years (minimum, 20 years; maximum,
was shared with the evaluators, except that the subjects 70 years). The evaluators were distributed, according to
were females, and they were asked to rate the attractive- gender, between 71 males (42.5%) and 96 females
ness of the smiles. The judges viewed all the images first (57.5%) and, according to their specialty, among 54 or-
and then assigned their scores.3,11,27 At the beginning of thodontists (32.2%), 54 dentists (32.2%), and 59 layper-
the survey, each evaluator mentioned their age in the sons (35.3%).
number of years, their gender, and their specialty. The results of the intraobserver reproducibility are
A power analysis was performed a priori to determine shown in Table II. The judge’s reliability scores were
the sample size, using G* power software for analysis of moderate to well, with a 95% confidence level.
variance (ANOVA) with repeated measures and taking The mean scores assigned to the smiling images, ac-
into consideration a power of 80%, an a error of 5%, cording to bracket prescription, skeletal Class, and view,
a correlation coefficient of 0.5, and a small effect size regardless of the specialty and gender of the evaluators,
of 0.1. The minimum number of required evaluators are shown in Table III.

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438 Kreichati et al

Fig 3. A, Brackets are selected from the OrthoAnalyzer library; B, The selected bracket prescription is
simulated, and the final position of the teeth is captured in frontal; C, Oblique; D, Sagittal views.

Fig 4. Final smiling images for the patient with a skeletal Class I malocclusion, obtained in 3 views
(frontal, oblique, and sagittal) and with 3 orthodontic brackets prescriptions (from left to right: Roth,
MBT, and Ricketts).

The tests results for the frontal view smiling images were found between the esthetic scores when comparing
are described as follows. For the patient with skeletal Ricketts to Roth and Ricketts to MBT, with the Roth pre-
Class I malocclusion, statistically significant differences scription receiving the highest scores (6.47 6 1.86) and

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Kreichati et al 439

Fig 5. Final smiling images for the patient with skeletal Class II malocclusion, obtained in 3 views (fron-
tal, oblique, and sagittal) and with 3 orthodontic brackets prescriptions (from left to right: Roth, MBT, and
Ricketts).

the Ricketts prescription receiving the lowest scores The tests results for the lateral view smiling images
(5.77 6 1.91). For the patient with skeletal Class II are described as follows. Statistically significant differ-
malocclusion, no statistically significant difference was ences in the scores were observed between the 3 pre-
found between the 3 prescriptions (P 5 0.286). For scriptions for the 3 patients, except between the Roth
the patient with skeletal Class III malocclusion, signifi- and MBT prescriptions for the patient with skeletal Class
cant differences were only observed between the Roth III malocclusion. In all 3 patients, the Roth prescription
and MBT prescriptions, with the highest scores attrib- received the highest scores (Class I, 6.38 6 1.76; Class
uted to Roth (5.49 6 10.92) and the lowest scores attrib- II, 5.32 6 2.07; Class III, 5.22 6 1.95), whereas the Rick-
uted to MBT (5.18 6 1.99). etts prescription received the lowest scores (Class I, 5.30
The tests results for the oblique view smiling images 6 1.85; Class II, 3.79 6 2.03; Class III, 4.66 6 2.05).
are described as follows. For the patients with skeletal The mean scores assigned by the 3 specialty groups to
Class I and II malocclusions, statistically significant dif- the smiling images, according to bracket prescription,
ferences were found between the esthetic scores when skeletal Class, and view, regardless of the age of the eval-
comparing Ricketts to Roth and Ricketts to MBT, with uators, are shown in Table IV.
the Ricketts prescription receiving the lowest mean The mean esthetic scores attributed by the 2 gender
scores: 5.80 6 2.02 for the patient with skeletal Class I groups, according to bracket prescription, skeletal Class,
malocclusion and 4.80 6 2.08 for the patient with skel- and view, regardless of the specialty, are shown in Table
etal Class II malocclusion. The highest scores were attrib- V. No significant difference between men and women is
uted to the MBT prescription for the patient with skeletal observed.
Class I malocclusion (6.56 6 1.83), and to the Roth pre- The results of the GEE model (with the dependent
scription for the patient with skeletal Class II malocclu- variable being the esthetic score) are presented in
sion (5.54 6 1.74). For the patient with skeletal Class Table VI.
III malocclusion, significant differences were noted be- The gender (P 5 0.801) and age (P 5 0.687) of the
tween the 3 prescriptions, with the Roth prescription evaluators did not affect the esthetic rating of smiles.
receiving the highest scores (5.72 6 1.87) and the Rick- Concerning the specialty, the scores from dentists
etts prescription receiving the lowest scores (4.29 6 were 10.5% lower than orthodontists’ scores (P 5
2.12). 0.005). In contrast, there were no significant

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440 Kreichati et al

Fig 6. Final smiling images for the patient with skeletal Class III malocclusion, obtained in 3 views (fron-
tal, oblique, and sagittal) and with 3 orthodontic brackets prescriptions (from left to right: Roth, MBT, and
Ricketts).

DISCUSSION
Table II. Intraobserver reproducibility results
The achievement of an esthetic smile involves a
Variables ICC 95% CI P value
multifactorial process, in which the positioning of the
Skeletal Class I 0.724 0.643-0.789 \0.001*
teeth in the esthetic zone plays a key role.1,2 In other
(Ricketts), frontal
view words, the 3D inclination and angulation of the teeth
Skeletal Class II (MBT), 0.756 0.683-0.815 \0.001* are crucial for both the harmony of the face and the
sagittal view smile.3-7,11,19 In clinical practice and with the straight-
Skeletal Class III 0.646 0.547-0.726 \0.001* wire technique, the teeth arrangement is primarily
(Roth), oblique view
dependent on the expression of the information incor-
ICC, intraclass correlation coefficient; CI, confidence interval. porated into the brackets.13 With the rise of multiple or-
*P \0.05. thodontic prescriptions since Andrews’s, one could
wonder which prescription would ideally create the
most esthetic smile.14-18
differences in the ratings between laypeople and ortho- To our knowledge, no study has evaluated the effect
dontists (P 5 0.369). of different straight-wire bracket prescriptions on smile
In terms of the smiling view, oblique view prescrip- esthetics. Despite the many orthodontic prescriptions
tion scores were 3.1% lower than frontal view scores and bracket designs available on the market, the
(P 5 0.031), and lateral view prescription scores were following 3 prescriptions were chosen: Roth, MBT, and
8.4% lower than frontal view scores (P \0.001). Ricketts. This particular choice was based on the notable
In terms of skeletal pattern, Class II scores were 15% differences in their respective torque values that may
lower than Class I scores (P \0.001), whereas Class III engender significant differences in the esthetic scores,
scores were 16.4% lower than Class I scores (P \0.001). with Roth offering low values, Ricketts offering the high-
In terms of orthodontic prescription, MBT scores est ones, and MBT in between.16 Therefore, the main
were 4% lower than Roth scores (P \0.001), whereas objective of this study was to evaluate the influence of
Ricketts scores were 13.6% lower than Roth scores orthodontic prescription on the attractiveness of a smile.
(P \0.001). Series of 3 smiling views were simulated with the

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Kreichati et al 441

Table III. Comparison of the esthetic scores between different orthodontic bracket prescriptions according to the
sagittal skeletal Class and the view, independently of the evaluators’ specialty and gender
Prescription

View Roth Ricketts MBT P value

Skeletal Class I
Frontal 6.47 6 1.86a 5.77 6 1.91b 6.14 6 1.82a \0.001*
Oblique 6.47 6 1.81a 5.80 6 2.02b 6.56 6 1.83a \0.001*
Lateral 6.38 6 1.76a 5.30 6 1.85c 6.13 6 1.86b \0.001*
Skeletal Class II
Frontal 5.71 6 1.95 5.50 6 2.04 5.70 6 2.11 0.286
Oblique 5.54 6 1.74a 4.80 6 2.08b 5.43 6 1.85a \0.001*
Lateral 5.32 6 2.07a 3.79 6 2.03c 4.98 6 2.15b \0.001*
Skeletal Class III
Frontal 5.49 6 1.92a 5.29 6 1.96ab 5.18 6 1.99b 0.044*
Oblique 5.72 6 1.87a 4.29 6 2.12c 5.03 6 1.88b \0.001*
Lateral 5.22 6 1.95a 4.66 6 2.05b 5.08 6 2.09a \0.001*
Note. Values are presented as mean 6 standard deviation. Superscripted letters indicate statistically significant differences between the different
bracket systems for each skeletal Class and smile view (a . b . c).
*P \0.05.

maxillary teeth positioned according to 3 types of ortho- brackets, and 0 and 8 for the Ricketts brackets.16 In
dontic prescriptions: Roth, Ricketts, and MBT, using the all 3 patients, the frontal view smiles showed no differ-
OrthoAnalyzer software. Moreover, the smiling series ence between the 3 bracket prescriptions, except for the
were obtained from 3 different patients chosen accord- patient with a skeletal Class I malocclusion when
ing to their sagittal skeletal pattern and were designed to comparing the Ricketts and Roth prescriptions, and the
be evaluated by groups of orthodontists, dentists, and Ricketts and MBT prescriptions, and for the patient
laypeople. The secondary objectives were as follows: to with a skeletal Class III malocclusion when comparing
evaluate the influence of orthodontic prescription on the Roth and MBT prescriptions.
smile attractiveness according to the sagittal skeletal Concerning the mesiodistal inclination of the ante-
pattern, to evaluate the effect of the specialty and rior teeth and according to the results of this study,
gender of the evaluators on the perception of smile es- the variation in second-order information between all
thetics, and to assess whether the frontal, oblique and 3 prescriptions did not seem to significantly alter the
sagittal views of the same smile achieve similar esthetic perception of the frontal smile. Yang et al7 studied the
scores. mesiodistal inclination of the maxillary central incisors
The establishment of the GEE model with the esthetic and found that the highest esthetic scores were attrib-
score as the dependent variable allowed us to meet the uted to a 0 inclination, similar to the Ricketts prescrip-
main objective of this study and to confirm that the or- tion in this study, followed by 2 tip back and 2 tip
thodontic prescription does influence the ratings. Ac- forward.
cording to these results, the MBT and Ricketts Concerning the buccolingual inclination of the pos-
prescription scores were 4.0% and 13.6% lower than terior teeth and according to Zachrisson,28 labially tilted
the Roth prescription scores, respectively. Accordingly, posterior teeth reduce negative transversal spaces and
the Roth prescription tends to obtain the most favorable help create a wide and radiant smile. However, according
esthetic scores. to this study, the different posterior torque values related
Frontal smiling photographs allow both the study of to the 3 concerned prescriptions did not seem to affect
the mesiodistal orientation of the anterior teeth7-9 as the esthetic frontal view ratings. In the patient with a
well as the labiolingual inclination of the lateral skeletal Class I malocclusion, the lowest score was attrib-
segments.10,11 Concerning the torques of the maxillary uted to the Ricketts prescription, whereas it was attrib-
canines and premolars, the Roth, MBT, and Ricketts pre- uted to the MBT prescription in the patient with a
scriptions present values of 2 and 7 , 7 and 7 , skeletal Class III malocclusion. In their study, Xu et al11
and 7 and 0 , respectively.16 The second-order infor- modified the angle formed between the facial axis of
mation of the central and lateral maxillary incisors is pre- the maxillary canines and premolars and the occlusal
sented as follows: 5 and 9 for the Roth and MBT plane using the OrthoRX software (Henghui Technology

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442 Kreichati et al

Table IV. Comparison of the esthetic scores, according to the specialty of the evaluators, and between different or-
thodontic bracket prescriptions according to the sagittal skeletal Class and the view
Specialty

Variables Orthodontists (n 5 54) Dentists (n 5 54) Laypeople (n 5 59) P value

Skeletal Class I
Frontal view
Roth 6.76 6 1.69a 6.15 6 1.95a 6.49 6 1.91 0.232
Ricketts 5.91 6 1.81b 5.33 6 1.83b 6.03 6 2.02 0.121
MBT 6.37 6 1.62ab 5.74 6 1.92ab 6.31 6 1.86 0.138
P value \0.001* 0.016* 0.065
Oblique view
Roth 6.80 6 1.69a 6.00 6 2.06ab 6.61 6 1.61a 0.055
Ricketts 5.85 6 1.94b 5.46 6 2.14b 6.07 6 1.96b 0.277
MBT 6.89 6 1.72a 6.46 6 2.02a 6.34 6 1.75ab 0.255
P value \0.001* 0.001* 0.036*
Sagittal view
Roth 6.81 6 1.66a 6.13 6 1.89a 6.20 6 1.67a 0.082
Ricketts 5.61 6 1.61b 4.85 6 1.98b 5.42 6 1.89b 0.083
MBT 6.72 6 1.65Aa 5.91 6 2.07ABa 5.78 6 1.73Bb 0.015*
P value \0.001* \0.001* \0.001*
Skeletal Class II
Frontal view
Roth 5.65 6 1.85 5.39 6 2.07 6.07 6 1.90a 0.174
Ricketts 5.76 6 1.83 5.24 6 1.99 5.51 6 2.27b 0.422
MBT 5.87 6 2.04A 4.72 6 2.10B 6.44 6 1.87Aa \0.001*
P value 0.681 0.070 \0.001*
Oblique view
Roth 5.65 6 1.86ABa 5.04 6 1.52B 5.92 6 1.74Aa 0.023*
Ricketts 4.76 6 2.34b 4.56 6 2.14 5.07 6 1.76b 0.373
MBT 5.89 6 1.85a 5.11 6 1.63 5.31 6 1.98b 0.074
P value \0.001* 0.059 \0.001*
Sagittal view
Roth 5.59 6 1.83a 5.85 6 2.02a 5.51 6 2.26a 0.122
Ricketts 4.22 6 1.92Ab 3.11 6 1.91Bc 4.02 6 2.12Ab 0.009*
MBT 5.67 6 1.91Aa 3.93 6 1.98Bb 5.31 6 2.18Aa \0.001*
P value \0.001* \0.001* \0.001*
Skeletal Class III
Frontal view
Roth 5.87 6 2.16 5.31 6 1.68a 5.31 6 1.88 0.212
Ricketts 5.56 6 2.19AB 4.67 6 1.78Bb 5.63 6 1.77A 0.016*
MBT 5.46 6 2.08 4.85 6 1.81ab 5.22 6 2.05 0.276
P value 0.113 0.016* 0.124
Oblique view
Roth 5.93 6 2.01a 5.33 6 1.80a 5.88 6 1.76a 0.182
Ricketts 4.24 6 2.20b 4.00 6 2.06b 4.61 6 2.09b 0.305
MBT 5.41 6 2.04a 4.85 6 1.58a 4.85 6 1.95b 0.200
P value \0.001* \0.001* \0.001*
Sagittal view
Roth 5.31 6 2.01AB 4.70 6 1.81Ba 5.61 6 1.95Aa 0.042*
Ricketts 5.17 6 1.95A 4.09 6 1.70Bb 4.73 6 2.31ABb 0.010*
MBT 5.48 6 2.09 4.70 6 1.99a 5.05 6 2.16b 0.154
P value 0.449 0.014* \0.001*
Note. Values are presented as mean 6 standard deviation. Superscripted capital letters indicate statistically significant differences between means
in the same row (A . B . C), whereas superscripted lowercase letters indicate statistically significant differences between means in the same column
(a . b . c).
*P \0.05.

Co, LTD, Xi’an, China) and found attractive inclination Lateral and oblique smiling photographs focus the
intervals ranging from 16 to 6 for the canines, and rater’s attention on the anteroposterior inclination of
11 to 1 for the premolars. the anterior teeth. For the maxillary central and lateral

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Kreichati et al 443

incisors, torque values of 12 and 8 are incorporated in

Table V. Comparison of the esthetic scores, according
the Roth prescription, 17 and 10 in the MBT prescrip-
to the gender of the evaluators, and between different
tion, and 22 and 14 degrees in the Ricketts prescrip-
orthodontic bracket prescriptions according to the
tion.16 For the profile and oblique smiling images of
sagittal skeletal Class and the view
the patient with a skeletal Class I malocclusion, signifi-
Gender cant differences were found between the 3 prescriptions,
Males Females
except when comparing the oblique Roth and MBT
Variables (n 5 71) (n 5 96) P value views. The Ricketts prescription offering the highest tor-
Skeletal Class I que values obtains the lowest scores. The sagittal view
Frontal view essentially assesses the inclination of the central incisors
Roth 6.32 6 1.93a 6.57 6 1.81a 0.394 and reveals, according to the results of this study, that
Ricketts 5.59 6 1.83b 5.90 6 1.96b 0.310
MBT 6.15 6 1.94a 6.14 6 1.73b 0.946
the best esthetic scores were attributed to the Roth
P value 0.002* 0.016* smiles, presenting 12 of labial crown torque. The ante-
Oblique view roposterior inclination of the maxillary incisors is widely
Roth 6.38 6 1.95a 6.54 6 1.70a 0.570 documented in the literature and proves to be a major
Ricketts 5.62 6 2.35b 5.94 6 1.73b 0.338 asset in sagittal smile attractiveness. Ghaleb et al3 stud-
MBT 6.45 6 2.02a 6.64 6 1.69a 0.522
P value \0.001* 0.001*
ied the angle formed between a tangent to the buccal
Sagittal view surface of the central incisor and the true horizontal
Roth 6.49 6 1.68a 6.29 6 1.82a 0.466 line when the head is placed in the esthetic position as
Ricketts 5.10 6 1.95c 5.45 6 1.77b 0.229 described by Bass. The results of their work showed
MBT 6.11 6 1.83b 6.14 6 1.89a 0.938 that an angle of 93.0 was considered to be the most
P value \0.001* \0.001*
esthetic; 76.0 , 82.0 (palatally tipped incisors), or
Skeletal Class II
Frontal view 97.5 (labially tipped incisors), were generally perceived
Roth 5.89 6 2.05 5.58 6 1.88 0.321 as unattractive. Cao et al4 modified the labiolingual
Ricketts 5.68 6 2.13 5.38 6 1.98 0.348 inclination, as well as the FA point position of the central
MBT 5.59 6 2.35 5.78 6 1.94 0.579 incisors with respect to the goal anterior limit line as
P value 0.425 0.105
Oblique view
described by Andrews, on lateral smiling images and
Roth 5.77 6 1.65a 5.38 6 1.80a 0.144 concluded that a straight or slightly palatally tipped
Ricketts 4.94 6 2.22b 4.70 6 1.98b 0.453 incisor is generally preferred over excessive labial incli-
MBT 5.72 6 1.61a 5.22 6 1.99a 0.085 nation that was considered unattractive. De Velasco
P value \0.001* \0.001* et al5 focused on the angle formed between a tangent
Sagittal view
to the labial surface of the maxillary incisors and the
Roth 5.48 6 2.08a 5.21 6 2.06a 0.404
Ricketts 3.72 6 1.93b 3.84 6 2.12b 0.695 functional occlusal plane and found favorable scores
MBT 5.20 6 2.19a 4.81 6 2.11a 0.254 for angle values of 70 , 75 , and 80 , which correspond
P value \0.001* \0.001* respectively to 20 , 15 , and 10 of torque as described
Skeletal Class III by this study. Naini et al6 concluded that a tangent to the
Frontal view
buccal surface of the maxillary central incisor should be
Roth 5.61 6 1.90 5.41 6 1.94a 0.509
Ricketts 5.27 6 1.90 5.31 6 2.01ab 0.884 approximately parallel to the true vertical when the pa-
MBT 5.42 6 1.93 5.00 6 2.02b 0.175 tient is placed in a natural head position.
P value 0.213 0.036* For the profile and oblique smiling images of patients
Oblique view with skeletal Class II and III malocclusions, the highest
Roth 5.54 6 1.75a 5.85 6 1.95a 0.276
Ricketts 4.30 6 2.22b 4.29 6 2.05c 0.990
scores were assigned to the Roth prescription, and the
MBT 5.03 6 1.81a 5.03 6 1.93b 0.992 lowest scores were assigned to the Ricketts prescription.
P value \0.001* \0.001* Dentoalveolar compensation seems more acceptable in
Sagittal view skeletal Class II cases to alleviate the skeletal dishar-
Roth 5.11 6 1.97a 5.30 6 1.94a 0.536 mony, whereas esthetic limits would oppose it in skeletal
Ricketts 4.41 6 2.07b 4.85 6 2.02b 0.165
Class III cases in which a more upright position of the
MBT 4.99 6 2.08a 5.15 6 2.11ab 0.627
P value 0.005* 0.035* maxillary incisors seems preferred to an overly labial
inclination. Zarif Najafi et al19 altered both the inclina-
Note. Values are presented as mean 6 standard deviation. Super-
scripted letters indicate statistically significant differences between tion of the maxillary incisors and the mandibular posi-
means in the same column (a . b . c). tion in the sagittal dimension and found that in
*P \0.05. patients with protrusive or retrusive mandible, the

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444 Kreichati et al

Table VI. GEE model: Esthetic score (dependent variable)

Parameter B SE P value aOR 95% CI
(Intercept) 1.945 0.0476 \0.001* 6.997 6.373-7.682
Specialty
Laypeople 0.034 0.0378 0.369 0.967 0.898-1.041
Dentists 0.111 0.0391 0.005* 0.895 0.829-0.966
Orthodontists (reference) 0.00 – – 1.00 –
Gender
Females 0.008 0.0310 0.801 0.992 0.934-1.054
Males (reference) 0 – – 1.00 –
Age 0.000 0.0011 0.687 1.000 0.998-1.003
Smiling view
Lateral 0.090 0.0148 \0.001* 0.914 0.888-0.941
Oblique 0.032 0.0147 0.031* 0.969 0.841-0.997
Frontal (reference) 0.000 – – 1.000 –
Skeletal sagittal pattern
Class III 0.180 0.0168 \0.001* 0.836 0.809-0.864
Class II 0.162 0.0205 \0.001* 0.850 0.817-0.885
Class I (reference) 0.000 – – 1.000 –
Orthodontic brackets
MBT 0.041 0.0072 \0.001* 0.960 0.946-0.973
Ricketts 0.146 0.0122 \0.001* 0.864 0.844-0.885
Roth (reference) 0.00 – – 1.000 –

Note. The independence model criterion was 3672.581, whereas the corrected independence model criterion was 3622.718.
SE, standard error; CI, confidence interval; aOR, adjusted odds ratio.
*P \0.05.

highest esthetic scores were related to a normal inclina- For the patient with compensated skeletal Class II
tion of the incisors, whereas retroclined maxillary inci- malocclusion, the Ricketts 22 prescription flared the
sors scored the lowest. central incisors, thus accentuating the skeletal discrep-
The results of the GEE model allowed us to meet the ancy, whereas the Roth prescription uprighted them
secondary objectives of this study. First, it could be es- into an esthetically perceived inclination of 12 . It would
tablished that the orthodontic prescription did influence be interesting to examine which prescription would be
the evaluation of the attractiveness of a smile according the most appropriate for skeletal Class II compensatory
to the sagittal skeletal pattern because the score was treatment in which intermaxillary elastics, as well as
15% lower in the patient with a Class II malocclusion retraction of the anterior segment, will be applied. The
than in the patient with a Class I malocclusion, whereas major undesirable movements relative to the use of Class
the score was 16.4% lower in the patient with Class III II elastics are the rabbiting, retraction, and extrusion of
malocclusion than in the patient with a Class I malocclu- the maxillary incisors, often associated with the wors-
sion. Moreover, different views of the same smile did not ening of a preexisting gummy smile.29 Therefore, the
rate similarly. Kerns et al23 highlighted the importance of choice of the most appropriate prescription should be
studying different perspectives during the clinical exam- related to the employed mechanics and should focus
ination of orthodontic patients after finding that photo- on anterior torque reinforcement to counteract the
graphs of the same smile in frontal and lateral views side effects of the elastics, an option that is offered by
received different scores, which could be attributed to the Ricketts prescription.16 In particular, treating
independent esthetic dimensions contained in each compensated Class II malocclusion with these mechanics
view.23 In this study, oblique and lateral view scores and ending up with ideally inclined maxillary incisors, as
were 3.1% and 8.4% lower than frontal view scores, described by the results of this study, would require the
respectively. These results showed that the labiolingual use of a high torque prescription. Furthermore, accord-
inclination of the maxillary incisors was generally judged ing to Zarif Najafi et al,19 in patients with mandibular
the most severely, particularly with the Ricketts prescrip- deficiency in which camouflage treatment is indicated,
tion, in patients presenting a dentally compensated a lingual inclination of the incisors compromises the es-
maxillomandibular discrepancy. The torque of the cen- thetics of the smile, which highlights the necessity of
tral incisors showed to be critical when assessing a smile. good torque control during retraction.

April 2024  Vol 165  Issue 4 American Journal of Orthodontics and Dentofacial Orthopedics
Kreichati et al 445

For the patient with compensated skeletal Class III probably focusing more on the intrinsic criteria of
malocclusion, the Roth prescription judged the most the subject to be evaluated.
favorably largely uprighted the central incisors, whereas The methodology of this study made it possible to
the Ricketts prescription highly torqued the originally transcend the limitations of previous work on dentoal-
flared centrals. A straight uprighted inclination seems veolar esthetics by using the OrthoAnalyzer software to
to be preferred to the compensation of the skeletal simulate the expression of different orthodontic pre-
discrepancy. The major adverse effect of the Class III in- scriptions and the consequent 3D spatial positioning
termaxillary elastics on the maxillary incisors is a flaring of the maxillary teeth visible on a smile. Moreover, the
movement.30 Consequently, it appears that the most results suggested that different views of the same smile
appropriate prescription will be the one offering reduced are assessed differently and highlighted both the impor-
torque values to counteract this side effect. Generally tance of the clinical examination of a smile in all dimen-
speaking, the choice of a prescription by an orthodontist sions for a complete diagnosis and the need to include
must be thoughtful and dependent on the adopted me- different smile views in research works, particularly those
chanics, the consequent dentoalveolar movements, and concerning dentoalveolar esthetics. Finally, the sample
the desired therapeutic objectives and must not be size of this study, allowed the construction of a GEE
related to the static dental configuration expressed by model that is an essential asset to determine the predic-
the orthodontic brackets. tors of the variation of the esthetic scores.
The ability to choose various prescriptions might be In this study, colored simulations of smiling photo-
possible in a teaching environment in which several graphs were used to convey details more realistically
different systems may be available. This is hardly the than with silhouettes, drawings, or black-and-white im-
case in most private practices in which inventory is ages. It can be argued that photographs reveal multiple
more restricted with the use of 1 appliance prescription intrinsic factors, such as eye color, nose shape, chin
for all patients. However, knowing the tendencies of a anatomy, skin texture, or emotional expression, that
particular prescription and the desired outcomes for a can affect the perception of smile attractiveness by dis-
particular patient may necessitate altering the prescrip- tracting the evaluators’ attention from other character-
tion, such as “flipping” the anterior brackets, which istics.19 To better control these bias factors, close-up
some clinicians recommend to reduce the proclination images of the lower third of the face were used to focus
of the maxillary incisors or bending torque in the arch- the attention on the teeth,4,26 especially because this
wire to better control such incisor inclination.31 survey was built around 3 different patients, each of
In this study, the gender of the evaluators did not them having their intrinsic factors. Three different sub-
seem to significantly affect the esthetic ratings. This jects were chosen to carry out the simulations in an
result agreed with previous work,11,19,20 although attempt to overcome the main limitation of single-
some authors have noted significant differences be- factor studies that focus only on a single variable, such
tween men and women.7 It seems that the apprecia- as the inclination of the teeth, without including other
tion of the concept of beauty is not related to factors that could potentially influence the attractive-
sexual dimorphism. In contrast, the results of this ness of a smile, such as soft-tissue, size, or shape of
study suggested that the specialty of the evaluators the teeth, making their conclusions difficult to apply
does influence the esthetic scores. When comparing to all patients. Multiplying the results by 3 was intended
laypeople to orthodontists, there was no significant to confirm results that would have been attained with a
variation in the ratings. This agreed with many single subject, although it was not possible to directly
studies,4,7,10,11 but is in disagreement with compare the scores obtained by different orthodontic
others.3,5,19,20 This may be caused by proper commu- prescriptions between the 3 patients. Therefore, it would
nication that is now taking place between orthodon- be interesting to undertake future studies with 2 vari-
tists and their patients, leading to a better ables, these being the orthodontic prescription as simu-
understanding of their posttreatment esthetic expecta- lated in this study and the mandibular position, to
tions. However, dentists were more severe in their as- simulate different degrees of sagittal shifts with different
sessments, with scores 10.5% lower than those of views of the same smile.
orthodontists. A difference in the ratings between
dentists and orthodontists is also found in other CONCLUSIONS
studies.3,5 With each dental specialty focusing on a
particular subject, it seems that smile esthetics criteria  A smile’s attractiveness is affected by the orthodontic
vary between orthodontists and dentists, the latter bracket prescription.

American Journal of Orthodontics and Dentofacial Orthopedics April 2024  Vol 165  Issue 4
446 Kreichati et al

 The Roth prescription tends to obtain the most favor- 10. Lemos TCB, Vasconcelos JB, Santos BMD, Machado AW. Influence
able esthetic scores, especially in sagittal smiling im- of maxillary canine torque variations on the perception of smile es-
thetics among orthodontists and laypersons. Dental Press J Orthod
ages, with the maxillary central incisors positioned in 2019;24:53-61.
a 12 labial crown torque. 11. Xu H, Han X, Wang Y, Shu R, Jing Y, Tian Y, et al. Effect of bucco-
 Profile smiles with incisors excessively inclined labi- lingual inclinations of maxillary canines and premolars on
ally are considered unattractive. perceived smile attractiveness. Am J Orthod Dentofacial Orthop
 Different views of the same smile do not get similar 2015;147:182-9.
12. Andrews LF. The six keys to normal occlusion. Am J Orthod 1972;
esthetic scores because sagittal views are rated the 62:296-309.
most severely. 13. Andrews LF. The straight-wire appliance. Br J Orthod 1979;6:
 The specialty of the evaluators influences the esthetic 125-43.
rating of the smiles, contrary to their gender and age. 14. Roth RH. The straight-wire appliance 17 years later. J Clin Orthod
 An orthodontic prescription should be selected on the 1987;21:632-42.
15. Roth RH. Five year clinical evaluation of the Andrews straight-wire
basis of the intended mechanics for the correction of appliance. J Clin Orthod 1976;10:836-50.
the skeletal disharmony, the consequent dentoalveo- 16. Planche P. L’evolution des techniques pre-informees depuis An-
lar movements, and the desired therapeutic objectives. drews. Rev Orthop Dento Faciale 1997;31:453-71.
17. McLaughlin RP, Bennett JC, Trevisi HJ. Systemized orthodontic
treatment mechanics; 2001.
AUTHOR CREDIT STATEMENT 18. Ricketts RM. Bioprogressive therapy as an answer to orthodontic
needs. Part I. Am J Orthod 1976;70:241-68.
Stephanie Kreichati contributed to conceptualiza- 19. Zarif Najafi HZ, Oshagh M, Khalili MH, Torkan S. Esthetic evalua-
tion, original manuscript preparation, methodology, tion of incisor inclination in smiling profiles with respect to
and investigation; Roula Akl contributed to supervision, mandibular position. Am J Orthod Dentofacial Orthop 2015;148:
manuscript review and editing, and project administra- 387-95.
tion; Adib Kassis contributed to supervision, manuscript 20. Jiang X, Cao Z, Yao Y, Zhao Z, Liao W. Aesthetic evaluation of the
labiolingual position of maxillary lateral incisors by orthodontists
review and editing, and project administration; and and laypersons. BMC Oral Health 2021;21:42.
Rami Aboujaoude contributed to investigation and orig- 21. El-Beialy AR. Planning digital indirect bonding with root aware-
inal manuscript preparation. ness. BJSTR 2018;5:4451-5.
22. Sarver DM, Ackerman MB. Dynamic smile visualization and
quantification: part 1. Evolution of the concept and dynamic re-
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