Does Andrews facial analysis predict esthetic sagittal maxillary position?

Occlusal characteristics in modern humans with tooth agenesis

Non-syndromic permanent tooth agenesis affects a significant proportion of the population, especially if third molars are considered. Although tooth agenesis has been linked to a smaller craniofacial size, reduced facial convexity and a shorter skeletal face, the occlusal characteristics of individuals with tooth agenesis remain largely unexplored. Therefore, this study investigated potential associations between tooth agenesis and metric occlusal traits in 806 individuals (491 with 4.1 missing teeth per subject, including third molars, and 315 without any tooth agenesis). Dentoskeletal morphology was defined through anatomical landmarks on pre-treatment cephalometric radiographs. Multivariate regression models, adjusted for sex and age, showed that tooth agenesis was significantly associated with a reduced overjet, an increased interincisal angle, and shorter upper and lower dental arch lengths, but not with overbite. Moreover, apart from reduced tooth length and dentoalveolar effects, as the number of missing teeth increased the upper front teeth were progressively retruded according to the craniofacial complex and to the face. Thus, tooth agenesis has a substantial influence on dental and occlusal characteristics, as well as on the sagittal position and inclination of anterior teeth. These findings emphasize the necessity for personalized, multidisciplinary approaches in individuals with multiple agenesis to successfully meet treatment goals.

Factors influencing the perception of profile beauty in Class III dental compensation: A comparative cross-sectional study according to three categories of assessors

INTRODUCTION

The main objective of this study was to evaluate the different factors influencing the perception of female profile facial beauty in Class III patients with protruded mandible that can be treated with orthodontic dental compensation: (1)severity of the protrusion, (2) the upper incisors inclination and (3) the presence of jawlines. The secondary objective was to determine if the rater's gender and profession played a role in the assessment of the preferred profile.

METHODS

A normal and smiling photographs of a female subject with normal facial and skeletal profile criteria were digitally manipulated to obtain 3 different mandibular sagittal positions: 0mm, +4mm and +8mm. Each position of the chin was evaluated with the presence or not of jawlines. In the smiling profiles, the same chin modifications were scored, and the maxillary incisor inclination was changed from 0 to +10 degrees with 5 degrees increments. A total of 320 raters (107 dentists, 103 orthodontists and 110 laypeople) scored the attractiveness of the different images using a Visual Analogue Scale. The limit of statistical significance was P<0.05. Generalized estimating equation (GEE) models were conducted to assess the predictors of variations in ratings within each set of photos, as well as the interactions of predictors where adjusted odds ratios (aOR) and their 95% confidence intervals were calculated and reported.

RESULTS

In the profiles without a smile, image +4mm chin (Class III treated by compensation) and image +8-mm mandible (Class III not treated) were selected as the most and least attractive images, respectively, by almost all groups with no difference. The presence of jawlines has a positive role in facial attractiveness. In the smiling profiles, all the examiners showed a preference for image +4-mm chin and a slight protrusion of maxillary incisors (+5 degrees). No significant difference was found between genders in this study.

CONCLUSIONS

Class III treated by compensation (+4mm) are more attractive than non-treated Class III (+8mm) by almost all groups with no difference. The presence of jawlines has a positive role in facial attractiveness. In the smiling profiles, all the examiners showed a preference for image +4-mm chin and a slight protrusion of maxillary incisors (+5 degrees). Orthodontists older than 50 years old are aware of the difficulty to treat a skeletal Class III and tend to accept it due to their long career experience. No significant difference was found between genders in this study.

Validation of Andrews Analysis in the Virtual Environment

BACKGROUND

Andrews analysis is a tool to establish the aesthetic anteroposterior position of the maxilla. Andrews analysis has not been evaluated through computer-aided surgical simulation (CASS).

PURPOSE

The purpose of this study was to evaluate the accuracy of Andrews profile analysis when performed in the virtual environment.

STUDY DESIGN, SETTING, SAMPLE

A retrospective cohort study was implemented with consecutive patients undergoing orthognathic surgery between February 2020 and February 2022 at the University of Alabama, Birmingham. Traditional Andrews analysis with lateral smiling photographs were taken during the presurgical appointment in adjusted natural head position (aNHP). The standard cone-beam CT obtained for CASS and archived on the KLS Martin (Jacksonville, Florida) database was accessed for retrospective measurement. Lateral facial photographs in aNHP were imported into the virtual environment and the three dimensional (3D) composite model was then oriented into aNHP. The software engineer, blinded to the traditional measurements, then performed the Andrews analysis in the virtual environment by placing a vertical glabella line on the 3D composite model in aNHP. The linear horizontal distance of the maxillary central incisor perpendicular to the vertical glabella line was recorded.

PREDICTOR/EXPOSURE/INDEPENDENT VARIABLE

Method of Andrews analysis measurement (traditional photographic evaluation vs CASS) MAIN OUTCOME VARIABLE: Linear Andrews analysis measurement.

COVARIATES

Additional covariates evaluated were sex, age at surgery, and dentofacial deformity diagnosis.

ANALYSES

Descriptive statistics were computed to compare photographic analysis versus CASS analysis. A P value of <.05 was considered statistically significant.

RESULTS

The average age was 25.7 years old and 54% of patients were female. For the photographic analysis, the mean incisor-goal anterior limit line distance was -0.44 ± 7.12 mm (95% CI, -1.13 to 0.37 mm; P = .46). For the virtual analysis, the mean incisor-goal anterior limit line distance was 0.13 ± 7.21 (95% CI, -0.004 to 0.30; P = .89). The Pearson correlation coefficients between the photograph and 3D analysis were very strong (0.93). The root mean square deviation between the photographic and 3D analysis cohorts was 2.7 mm.

CONCLUSION AND RELEVANCE

Given the high correlation coefficients between all demographics, CASS can be utilized for Andrews analysis to determine ideal anteroposterior maxillary position to streamline data collection and the planning process.

Barcelona line. A multicentre validation study of a facial projection reference in orthognathic surgery

The purpose of this study was to validate an already published facial anteroposterior reference: upper incisor (UI) to soft tissue plane or so-called Barcelona line (BL) to trace the most aesthetic sagittal position of the maxilla. A cross-sectional multicentre evaluation of Caucasian patients from Spain and Brazil with different anteroposterior maxillary positions was designed. Sagittal images in natural head orientation of grouped patients according to the horizontal distance from the UI to BL were ranked by healthcare professionals and non-professional Caucasian raters according to the aesthetic perception of each profile, using a digital survey. Seventy-four raters (50 laypeople, 12 orthodontists, and 12 maxillofacial surgeons) rated 40 profiles. The best-rated profile corresponded to group 3 (0-4 mm UI-BL) with 61.8% of positive evaluations, followed by group 4 (≥ 4 mm UI-BL): with 61.1%. On the other hand, group 1 (≤-4 mm UI-BL) was the worst-ranked profile with 71.8% of negative evaluations, followed by group 2 (-4-0 mm UI-BL): with 59.6% of negative evaluations. The correlation between the mean assessment score and UI-BL showed a moderately-strong association (r = 0.68, p < 0.001). The inter-rater reliability of assessment (74 evaluators) was moderate (k = 0.49, 95% CI: 0.39 to 0.59). The results suggest that protrusive middle-third facial profiles are preferable. The BL is proposed as a simple, individualised, and reproducible tool to trace an aesthetic sagittal position of the maxilla in orthognathic surgery.

Three-dimensional zygomatic changes after rapid maxillary expansion in growing patients

PURPOSE

To assess the effects of rapid maxillary expansion (RME) treatment on the zygomatic bone complex (ZBC).

METHODS

In this single-center retrospective study, pre- and posttreatment cone-beam computed tomography (CBCT) images of 38 patients treated with RME were analyzed to investigate changes in the coordinates of the ZBC landmarks. At the start of treatment (T0), the patients' mean age was 11.1 ± 3.8 years (range 8.3-14.9 years). Cohen's d test was used to evaluate statistical differences.

RESULTS

There were statistically significant differences between T0 and T1 (P < 0.01) in the measurement values for the maxillary transverse width (ΔT: 3.18 ± 2.58, d: 1.23), frontozygomatic sutures (ΔT: 1.09 ± 0.56, d: 0.43), lowest point of the zygomaticomaxillary sutures (ΔT: 3.16 ± 1.78, d: 0.78), frontomaxillary angular parameter (right side ΔT: 2.81 ± 1.63, d: 1.73; left side ΔT: 2.52 ± 1.20, d: 2.10), frontozygomatic angular parameter (right side ΔT: 2.81 ± 1.63 d: 1.07; left side ΔT: 2.21 ± 2.79, d: 0.61), anterior intermaxillary distance (ΔT: 2.11 ± 1.42, d: 0.99), interzygomaticotemporal distance (ΔT: 2.00 ± 2.42, d: 0.99), and zygomatic angular parameter (right side ΔT: 2.06 ± 1.29, d: 1.6; left side ΔT: 2.02 ± 1.86, d: 1.09).

CONCLUSIONS

After RME in growing patients, the zygomatic bone showed pyramidal expansion in the coronal plane and parallel palatal expansion in the axial plane. In addition, significant lateral relocation of the zygomatic bone occurred. The zygomatic bone tended to rotate outward in conjunction with the maxilla, with a typical center of rotation close to the superior side of the frontozygomatic suture. These results shed light on the patterns of skeletal expansion in the zygomatic bone associated with RME in growing patients.

The influence of incisor inclination and anterior vertical facial height on facial attractiveness in an Asian woman

INTRODUCTION

Orthodontic treatment can help improve facial attractiveness through the modification of factors affecting the soft tissue profile. The objectives of this study were to determine the impact of different maxillary incisal inclinations and lower anterior facial heights (at rest and with a smile) on the facial attractiveness of an Asian woman, as perceived by different panels of raters using visual analog scale (VAS) scores.

METHODS

A cross-sectional study was performed with 66 raters equally divided into 3 panels that consisted of general dentists, orthodontic residents, and laypersons. Raters assessed modified photographs of a subject with various incisor inclinations and lower anterior facial height/total anterior facial height (LAFH/TAFH) on lateral profile view. Modifications were made using Photoshop software (Adobe, San Jose, Calif). Subjective evaluations of facial attractiveness were performed by raters using VAS. Kruskal-Wallis test was used to compare VAS scores among raters. Mann-Whitney U test was applied to compare VAS scores between groups.

RESULTS

Significant differences in VAS scores were found among raters for -10° (P = 0.004) and -15° (P = 0.021) incisal inclinations. Significant differences were found in VAS scores for -8% LAFH/TAFH (P = 0.044) and 4% LAFH/TAFH with smile (P = 0.002).

CONCLUSIONS

Professionals preferred normal incisal inclinations to be the most attractive. General dentists found reduced facial height to be unattractive. Orthodontic residents and laypersons considered increased LAFH/TAFH to be most unattractive. Smile had a negative impact on VAS scores at extreme anterior facial height modifications.