Attractiveness of the facial profile: comparison of Class II patients treated with Twin Force® or intermaxillary elastics

ABSTRACT Objective: To compare the facial profile attractiveness of Class II patients treated with Twin Force® or intermaxillary elastics. Methods: Sample comprised 47 Class II patients divided into two groups: G1) TWIN FORCE - 25 patients treated with fixed appliances and Twin Force® fixed functional appliance (mean initial age was 17.91 ± 7.13 years, mean final age was 20.45 ± 7.18 years, and mean treatment time was 2.53 ± 0.83 years); G2) ELASTICS - 22 patients treated with fixed appliances and Class II intermaxillary elastics (mean initial age was 15.87 ± 5.64 years, mean final age was 18.63 ± 5.79 years and mean treatment time was 2.75 ± 0.60 years). Lateral cephalograms from pretreatment and posttreatment were used. Cephalometric variables were measured and silhouettes of facial profile were constructed and evaluated by 48 laypeople and 63 orthodontists, rating the attractiveness from 0 (most unattractive profile) to 10 (most attractive profile). Intergroup comparisons were performed with Mann-Whitney and independent t-tests. Results: At pretreatment, facial profile of the Twin Force® group was less attractive than the Elastics group. Treatment with Twin Force® or Class II elastics resulted in similar facial profile attractiveness, but the facial convexity was more reduced in the Twin Force® group. Orthodontists were more critical than laypeople. Conclusions: Treatment with Twin Force® or Class II elastics produced similar facial profile attractiveness at posttreatment. Profile attractiveness was reduced with treatment in the elastic group, and improved in the Twin Force® group. Facial convexity was more reduced with treatment in the Twin Force® group.


INTRODUCTION
In the Class II treatment with intermaxillary elastics or fixed functional appliances, all skeletal and dentoalveolar changes produce effects on the soft tissue profile. [1][2][3][4][5][6] Therefore, it is extremely important for the orthodontists to understand these effects to better perform the treatment planning and fulfill the esthetic expectation of each patient.
The interest in facial esthetics increases the search for orthodontic treatment; therefore, the modern orthodontics advances not only in the search for dental correction, but also at improving facial esthetics. The facial attractiveness is positively correlated with self-esteem, interpersonal and professional relationships. 7 The appreciation of beauty is highly subjective. [8][9][10][11] The attractiveness of the facial profile is a controversial subject in the literature, when comparing the perception of professionals and laypeople. 12 Some studies show similar results among orthodontists and laypeople, [12][13][14][15] while others show divergence of opinion. 11,16,17 The satisfaction with facial and dental appearance is a predictor to know the patients' expectations about orthodontic treatment. 18 Pozza OA, Cançado RH, Valarelli FP, Freitas KMS, Oliveira RC, Oliveira RCG -Attractiveness of the facial profile: comparison of Class II patients treated with Twin Force ® or intermaxillary elastics 5 A previous study comparing the changes in profile attractiveness in children with Class II malocclusion treated with functional appliances and untreated subjects showed no difference, and the attractiveness was not improved with treatment. 19 However, other studies with fixed and removable functional appliances showed improved facial profile attractiveness. [20][21][22] Mendes et al. 23 found similar attractiveness for nonextraction Class II treatment when compared to 2-and 4-premolar extraction. Janson et al. 1 found similar soft tissue changes between Class II treatment with fixed functional appliances or maxillary premolars extraction.
Using cephalometric methods, the mandibular protraction appliance known as AdvanSync ® was compared to intermaxillary elastics in the Class II treatment and both showed to be effective. AdvanSync ® showed maxillary skeletal growth restriction and mandibular dentoalveolar changes, and Class II elastics showed only dentoalveolar changes. 24 When compared to the Forsus ® mandibular protraction appliance, the Class II elastics showed similar treatment changes. 25 Recent researches have indicated that orthodontic treatment with functional appliances is associated with increased facial profile attractiveness, 20,26,27 and that functional treatment should be considered as a treatment option to improve the facial appearance of Class II subjects. 26 Besides, Class II Pozza OA, Cançado RH, Valarelli FP, Freitas KMS, Oliveira RC, Oliveira RCG -Attractiveness of the facial profile: comparison of Class II patients treated with Twin Force ® or intermaxillary elastics 6 treatment with the Herbst appliance may produce a more esthetically improved facial profile silhouette when compared to the Forsus ® appliance, but the changes perceived by evaluators may not be considered clinically relevant. 27 In the literature, no study comparing the attractiveness of the facial profile of patients with Class II malocclusion treated nonextraction with intermaxillary elastics or fixed functional appliances could be found. In this context, the present study aimed to compare the facial profile attractiveness in Class II patients treated with the functional fixed appliance Twin Force Bite Corrector ® or Class II intermaxillary elastics, evaluated by orthodontists and laypeople.

This study was approved by the Ethics in Human Research
Committee of the Centro Universitário Ingá -Uningá (protocol 70881517.2.0000.5220).
The sample size calculation was based on an alpha significance level of 5% and a beta of 20% to achieve 80% of test power to detect a minimum difference of 0.88 points in the score of profile attractiveness, with a standard deviation of 1.02. 23   Inc., Carlsbad, CA, USA) was installed and used for six to nine months. The TFBC is a fixed, intermaxillary functional appliance with ball-and-socket joint fasteners that allow a wide movement, including laterality. 28 The appliance includes two telescopic tubes with NiTi coil springs that allows the delivery of a constant force. 28 In Group 2, Class II intermaxillary elastics were used for 1 to 1.75 years. In both groups, Class II mechanics was used until a Class I molar and canine relationships were obtained.
Lateral cephalograms were evaluated in the initial (T 1 ) and final years -laypeople were defined as individuals without formal education in dentistry or dental hygiene.

ERROR STUDY
The reliability and precision of the methodology were verified by the Kappa coefficient in 20 randomly selected silhouettes, in which the attractiveness was reevaluated within a month interval. The Kappa coefficient was 0.85, considered an excellent agreement. 30 After one month from the first measurements, 30 lateral cephalograms randomly selected were remeasured, and the intraclass correlation coefficient (ICC) was applied. All variables showed values of ICC above 0.9, indicating excellent agreement and reliability.

comparability of initial and final ages, treatment time and
Little irregularity index was verified with independent t-test.
Intergroup comparability of sex distribution and severity of the Class II malocclusion was verified by chi-square test.

RESULTS
Groups 1 and 2 were comparable regarding initial and final ages, treatment time, Little irregularity index, sex distribution, severity of Class II malocclusion and pretreatment cephalometric variables (Tables 1, 2 and 3).
At pretreatment, the Twin Force group presented a less attractive facial profile than the elastics group (Table 2). At posttreatment, facial profile attractiveness was similar between the groups ( Table 2). In intragroup comparison of T 1 and T 2 , the Twin Force ® group showed improvement of the facial profile attractiveness with treatment, and the Elastics group showed a reduction of the attractiveness of the profile (Table 2).
At pretreatment, the Twin Force ® and Elastics groups presented similar maxillomandibular skeletal discrepancy, incisor position, overjet, overbite and facial convexity (Table 3). Treatment changes of both groups were similar, except for the facial convexity that was more reduced in the Twin Force ® group than in Class II elastics group ( Table 3).
The groups of orthodontists and laypeople were comparable regarding age and sex distribution (Table 4). Orthodontists were significantly more critical than laypeople in the evaluation of facial profile attractiveness at pre-and posttreatment (Table 5).     Table 4: Results of comparability of age and sex distribution between the groups of evaluators (A -Orthodontists and B -laypeople). Table 5: Comparison of facial profile attractiveness at pretreatment (T 1 ) and posttreatment (T 2 ) between orthodontists and laypeople (Mann-Whitney nonparametric test).
T independent t-test; α chi-square test.  The Twin Force ® and Elastics groups were comparable regarding initial and final ages, treatment time, mandibular anterior crowding, sex distribution, severity of Class II malocclusion and initial cephalometric characteristics (Tables 1 and 3). The Twin Force ® group presented a less attractive facial profile than the Elastics group at pretreatment stage ( Table 2). This is probably because the Twin Force ® group presented a Class II slightly more severe than the elastics group, even though not significant statistically. The Twin Force ® group comprised 6 patients with full-cusp Class II molar relationship, and the Elastics group, only 2 patients (Table 1). This feature probably indicates a more convex and deficient facial profile in the Twin Force ® group, justifying the differences in the comparison of the pretreatment attractiveness between the groups. In cephalometric comparison of pretreatment stage, the facial convexity of the Twin Force ® group was greater, but without statistically significant difference from the elastics group (Table 3).
At the end of orthodontic treatment, there was no statistically significant difference of the facial profile attractiveness between the groups ( In intragroup comparison of pre and posttreatment stages, the Twin Force ® group showed a statistically significant improvement in facial profile attractiveness (Table 2). Since the Twin Force ® group presented a less attractive profile in the initial stage, and a slightly more convex profile and slightly greater mandibular retrusion, with no significant difference from the Elastics group, the use of the mandibular functional appliances was well indicated in these cases. 6,24,25 With treatment, the profile convexity decreased and the facial profile attractiveness was improved, as already showed in previous studies evaluating fixed and removable functional appliances. 20,22,26,27,38 However, the Elastics group showed a statistic significant reduction in the score of facial profile attractiveness with treatment ( Table 2). The intergroup comparison of treatment changes showed that the facial convexity was more reduced in Twin Force ® than in elastics group (Table 3). In the elastics group, at pretreatment, the patients presented slightly smaller maxillomandibular discrepancy, indicating mainly dentoalveolar Class II problems, with less involvement of the facial profile, which may have resulted in a higher score of facial profile attractiveness, even observing in the cephalometric variables that there was a slight decrease in the facial convexity (Table 3).

Treatment with Class II elastics can cause palatal inclination
and retrusion of the maxillary incisors, and consequent retrusion of the upper lip, compromising the facial profile attractiveness. 3,39 A previous study indicated that more prominent upper lips, less protruded lower lips, and more prominent chin might look more attractive. 39 Regarding the evaluators, orthodontists were significantly more critical than laypeople in the evaluation of facial profile attractiveness at pretreatment and posttreatment stages (Table 4).
This finding corroborates previous studies evaluating pre-and posttreatment silhouettes of orthodontically treated patients, which also found that orthodontists are more esthetically demanding than laypeople. 20,40,41 Pozza OA, Cançado RH, Valarelli FP, Freitas KMS, Oliveira RC, Oliveira RCG -Attractiveness of the facial profile: comparison of Class II patients treated with Twin Force ® or intermaxillary elastics 20 These differences between orthodontists and laypeople could be justified because orthodontists have more knowledge regarding facial profiles, and the facial esthetic is related to straight and less convex profile. 20,27 The perception of facial esthetics is not easy to understand and is highly subjective. The opinions of orthodontists, mostly in relation to dentofacial esthetics, take into consideration the ideal norms, guidelines and proportions, while the opinions of laypeople are motivated mainly by subjective feelings, such as culture of beauty and social norm of their environment. [42][43][44] CONCLUSION Treatment with Twin Force ® or Class II elastics produced similar facial profile attractiveness at posttreatment. Profile attractiveness was reduced with treatment in the Elastics group, and improved in the Twin Force ® group. Facial convexity was more reduced with treatment in the Twin Force ® group.