Long-term profile attractiveness of patients with Class I and II malocclusion treated with and without extractions: A 35-year follow-up

Introduction

The objective of this study was to compare the profile attractiveness in subjects treated with and without extractions after the long-term 35-year follow-up, according to laypeople, dentists, and orthodontists.

Methods

A total of 40 patients with Class I and II malocclusion were divided into 2 groups, according to the treatment protocol: extraction (E) group, extractions of 4 premolars (n = 24), with mean pretreatment (T1), posttreatment (T2), and long-term posttreatment (T3) ages of 13.13, 15.50 and 49.56 years, respectively. The mean treatment time (T2 − T1) was 2.37 years, and the long-term follow-up (T3 − T2) was 34.19. Nonextraction (NE) group (n = 16), with mean ages at T1, T2, and T3 of 13.21, 15.07, and 50.32 years, respectively. The mean (T2 − T1) was 1.86 years, and the (T3 − T2) was 35.25 years. Lateral cephalograms were used to perform profile facial silhouettes, and an online evaluation was performed by 72 laypeople, 63 dentists, and 65 orthodontists, rating the attractiveness from 1 (least attractive) to 10 (most attractive). The intragroup comparison was performed with the repeated measures analysis of variance and Tukey tests. Intergroup comparison was performed with t tests, 1-way analysis of variance, and Tukey tests.

Results

The E group had a longer treatment time than that of the NE group. In the pretreatment, posttreatment, and long-term posttreatment stages, the E and NE groups showed similar profile attractiveness. Laypersons and dentists were more critical than orthodontists.

Conclusions

At long-term posttreatment follow-up, profile attractiveness was similar in patients treated with and without extractions.

Highlights

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Subjects treated with the extraction of 4 premolars had a longer treatment time.
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Profile attractiveness is similar in the pretreatment, posttreatment, and long-term posttreatment phases in extraction and nonextraction groups.
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Laymen and dentists were more critical than were orthodontists.

The human face plays a pivotal role in assessing attractiveness and physical beauty. Esthetic facial balance is a primary goal in orthodontic treatment, alongside well-aligned teeth and an excellent occlusal relationship, often motivating patients to seek care. However, assessing the harmony and beauty of a face, which is a subjective characteristic, is personal and complex to measure. Furthermore, a harmonious face is not necessarily pleasant. ^,

The extraction of teeth for malocclusion treatment has been a subject of significant debate. Extractions were a prevalent approach a century ago and are still employed today to achieve facial harmony. The long-term stability of extraction treatments was demonstrated in subjects with Class I and II malocclusions, ^, in addition to the efficacy of treatment with and without extractions. ^,

Depending on the treatment chosen, there is a concern about the effects of orthodontic treatment on the facial profile and attractiveness. Some researchers have analyzed the effect of orthodontic treatment with and without extractions on the profile with controversial results. Some studies suggested that extraction of premolars flattens the facial profile, whereas others claimed that with proper diagnostic criteria, it would not adversely affect it. ^, ^, In contrast, there is a claim that this finding lacks evidence in most patients.

Long-term studies following treatments with and without extractions have not found significant cephalometric or esthetic differences 15 years after treatment. However, there is a lack of information regarding the outcomes beyond a 35-year treatment span. ^, Some researchers suggest a positive correlation between the change in the position of the lips and the change in the profile. ^, Other demonstrated changes in growth in late adolescence, aging in the facial profile, such as the closing of the nasolabial angle, lip retrusion, and an increase in the soft tissue of the chin. However, extractions do not negatively affect the facial soft-tissue profile over time.

According to the literature, the controversy of the results on the influence of tooth extractions and attractiveness can be seen because soft tissues are related to beauty ideals and are influenced by aging. It is essential to observe how they are influenced by orthodontic mechanotherapy in the short and long term. No previous study compared long-term profile attractiveness with extraction and nonextraction mechanotherapy after 35 years. Therefore, this study aimed to compare long-term profile attractiveness in subjects treated with and without extractions, according to laypeople, dentists, and orthodontists, after a long-term follow-up of 35 years.

Material and methods

This retrospective study was approved by the Research Ethics Committee of the Bauru Dental School, University of São Paulo, Bauru, SP, Brazil (protocol no. CAAE: 51079121.1.0000.5417).

The sample size calculation was based on an α significance level of 5% and a β of 20% to achieve 80% test power to detect a minimum difference of 0.86 points in the score of profile attractiveness, with a standard deviation of 0.8. The sample size calculation showed the need for 15 subjects per group.

The retrospective sample was selected from files at Bauru Dental School, University of São Paulo, Bauru, SP, Brazil, according to the following inclusion criteria: (1) Class I or II malocclusions at the beginning of orthodontic treatment; (2) treatment protocol of nonextraction or with the extraction of 4 first premolars; (3) complete orthodontic treatment with maxillary and mandibular fixed edgewise appliance (0.022 × 0.028-in slot); (4) all permanent teeth up to the first molars erupted before the beginning of treatment; (5) no tooth agenesis or anomalies; and (6) maxillary removable appliance (Hawley plate) worn for 1 year, mandibular fixed canine-to-canine retainers worn for at least 1 year, and a maximum of 3 years after treatment, without retention at the time of follow-up.

The sample comprised lateral cephalograms of 40 subjects obtained at 3 different time points: pretreatment (T1), posttreatment (T2), and long-term follow-up (T3).

The sample was divided into 2 groups according to the protocol orthodontic treatment: the extraction (E) group comprised 24 subjects (16 females and 8 males). A total of 11 presented Class I malocclusion, whereas 13 presented Class II malocclusion. The mean pretreatment age was 13.13 ± 2.21 years, the mean treatment time (T2 − T1) was 2.37 ± 0.63 years, and the long-term follow-up (T3 − T2) was 34.19 ± 5.17 years ( Table I ). The nonextraction (NE) group (NE group) comprised 16 subjects (10 females, 6 males). Six subjects presented Class I malocclusion, and 10 presented Class II malocclusions. The mean T1 age was 13.21 ± 0.83 years, the mean treatment time (T2 − T1) was 1.86 ± 0.83 years, and the mean long-term follow-up evaluation time (T3 − T2) was 35.25 ± 6.11 years ( Table I ).

Table I

Intergroup comparability of the pretreatment, posttreatment, and long-term posttreatment ages, treatment time, time of long-term posttreatment evaluation, retention time, sex distribution, and type of malocclusion (independent t and chi-square tests)

Variables	E group (n = 24)	NE group (n = 16)	P value
Pretreatment age (y)	13.13 ± 2.21	13.21 ± 0.83	0.893 ^§
Posttreatment age (y)	15.50 ± 2.34	15.07 ± 1.16	0.498 ^§
Long-term posttreatment age (y)	49.56 ± 6.45	50.32 ± 6.05	0.710 ^§
Treatment time (y)	2.37 ± 0.63	1.86 ± 0.83	0.032 ^∗^,^§
Long-term posttreatment time (y)	34.06 ± 5.17	35.25 ± 6.11	0.558 ^§
Retention time (y)	2.65 ± 1.48	2.26 ± 1.18	0.387 ^§
Sex ^†			0.787 ^\|\|
Females	16	10
Males	8	6
Malocclusion type ^‡			0.0602 ^\|\|
Class I	11	6
Class II	13	10

Note. Values are presented as mean ± standard deviation.

† χ ²= 0.07; degrees of freedom = 1.

‡ χ ²= 0.27; degrees of freedom = 1.

∗ Statistically significant for p <0.05

§ Independent t test.

|| Chi-square test.

The lateral cephalograms of the subjects were digitized. The dentoskeletal and soft-tissue cephalometric landmarks were performed using Dolphin Imaging software (version 11.5; Dolphin Imaging and Management Solutions, Chatsworth, Calif). The tracings obtained were standardized with the Frankfort plane horizontally oriented.

The images were converted in black and white and clipped using the Photoshop CC software (version 19.1.6; Adobe Systems, San Jose, Calif) ( Fig ). The clipped standardization was superiorly 1 cm above the glabella point, anteriorly 1 cm from the tip of the nose, inferiorly 2 cm below the throat point, and posteriorly through the condylion point. ^,

All silhouettes were randomized by Microsoft Excel software (Microsoft, Redmond, Wash). A questionnaire was created on Google Forms (Google LLC, Mountain View, Calif). Questions about education level, age, and profile silhouettes were inserted. The volunteers were invited to participate by the WhatsApp messaging application (Meta Platforms, Menlo Park, Calif), and all subjects signed informed consent forms.

The evaluator sample size calculation was performed to detect a difference of 0.7 points on a scale of 1-10, with a standard deviation of 1.28 points, an α significance level of 5%, a β of 20%, and a test power of 80%. The sample size calculation indicated the need for a minimum of 53 subjects in each evaluator group.

The volunteers were divided into 3 groups according to education degree. Laypeople comprised 72 subjects (43 females and 29 males) with a mean age of 33.40 years. Dentists included 63 subjects (40 females and 23 males) with a mean age of 30.24 years. Orthodontists comprised 65 subjects (36 females and 29 males) with a mean age of 33.58 years. The laypeople were defined as persons without formal education in dentistry or dental hygiene; the dentists were specialists with formal education; and the orthodontists were dental surgeons with completed graduate degrees in orthodontics.

The evaluators were blinded to the groups and stages of each profile evaluated. Profile attractiveness was rated on a 10-point numerical rating scale (NRS), ranging from 1 (least attractive profile) to 10 (most attractive profile). The evaluator could modify the scores before submitting the form.

To evaluate the precision of the evaluators, 2 profile silhouettes were randomly repeated throughout the questionnaire, and the intraclass correlation coefficient was used. The intraclass correlation coefficient of the precision of the evaluators in rating the profile attractiveness was 0.92, indicating an excellent intrarater agreement.

Statistical analyses

The normal distribution of all quantitative variables was evaluated using Shapiro-Wilk tests. Intergroup comparability of sex distribution and type of malocclusion were performed with chi-square tests, and the pretreatment; posttreatment; and long-term posttreatment ages, treatment time, time of long-term posttreatment evaluation, and retention time were compared by independent t tests. In the intragroup comparison of pretreatment, posttreatment, and long-term posttreatment stages, the repeated measures analysis of variance and Tukey tests were used. For comparison of the profile attractiveness in the long-term among the groups treated with extraction and nonextraction was used independent t test, and a comparison of the score of profile attractiveness given by laypeople, dentists, and orthodontists at T1, T2, and T3, in both was performed with 1-way analysis of variance and Tukey tests. All tests were performed using the software Statistica (version 12.0; StatSoft, Tulsa, Okla), and results were considered significant for P <0.05.

Results

The groups were comparable regarding pretreatment, posttreatment, and long-term posttreatment ages, time of long-term posttreatment evaluation and retention time, sex distribution, and type of malocclusion ( Table I ). The E group presented a greater treatment time than that of the NE group ( Table I ).

Both groups significantly improved the profile attractiveness with treatment and a statistically significant decrease in the long-term posttreatment follow-up ( Table II ). This long-term decrease made the profile attractiveness scores even less than the pretreatment scores in both groups ( Table II ).

Table II

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