Does facial growth pattern affect the perception of lower facial asymmetry?

OBJECTIVES: To investigate the influence of vertical facial type on esthetic perception of lower facial asymmetry as evaluated by orthodontists, dentists, and laypeople. MATERIALS AND METHODS: Three adult females were selected with normal growth patterns (NGP), vertical growth patterns (VGP), and horizontal growth patterns (HGP). Frontal photographs were made symmetric and digitally altered, rotating the lower facial third clockwise, ranging from 0° to 6° in 1° increments. A web-based survey was designed with 24 images (eight images for each model) in random order. Each image was rated using a scale ranging from 0 (unattractive) to 10 (the most attractive) by 75 orthodontists, 73 dentists, and 78 laypeople. Kruskal-Wallis test was used to determine whether differences among groups were significant. Pairwise comparisons were made with Mann-Whitney U test. The significance level was set at P = .05. RESULTS: In NGP, orthodontists and dentists could recognize slighter deviations (2°), while deviations in VGP and HGP under 3° were not recognized by all groups. Severe deviations (≥4°) were distinguished better in HGP by orthodontists and laypeople. In VGP and NGP, there was no significant difference over 4°. CONCLUSIONS: Growth pattern has a significant influence on perception of lower facial asymmetry. Less severe asymmetry can be detected better in NGP. In severe degrees, increments of asymmetry can be perceived more in HGP by orthodontists and laypeople.

Relationship Between Circummaxillary and Intramaxillary Suture Densities and Skeletal Effects of Rapid Maxillary Expansion.

Objective: This retrospective clinical study aimed to evaluate the maturation of intramaxillary and circummaxillary suture systems and cervical vertebral maturation as predictors of the skeletal response achieved by rapid maxillary expansion (RME). Methods: A Digital Imaging and Communication in Medicine dataset of 20 patients (mean age: 15.55 years) prior (T0) and after (T1: 3.5±0.5 months) to RME were retrieved from the archive and analyzed. Bone density values of midpalatal suture (MPS), zygomaticomaxillary suture (ZMS), zygomaticotemporal suture (ZTS), pterygopalatine suture (PPS), and transverse palatine suture (TPS) were measured. The cervical vertebral maturational stages (CVS) were examined. The linear distances between the most lateral points of the piriform apertures were measured as the anterior reference, and the medial margins of the greater palatine foramina on the axial slice were chosen as the posterior reference. The difference at T1-T0 was calculated as the skeletal response to RME at anterior and posterior skeletal references. Spearman's rho rank and Kruskal-Wallis tests were used. Results: Mean density values of ZMS, PPS, ZTS, TPS, MPS-Anterior, and MPS-Posterior were 922.81, 807.44, 753.83, 640.77, 661.13, and 604.59 HU, respectively. Mean linear changes in anterior and posterior skeletal expansion were 2.93±1.78 and 1.93±2.52 mm. There was no significant relationship between maturation indicators and skeletal response. Significant relationships were found between CVS and MPS density and CVS and circummaxillary suture average density (p≤0.05). Conclusion: Sutural density showed significant variations among CVSs. Although there was no correlation between skeletal response and density measurements, sutural density was found to be a promising indicator for future studies.

Facial morphology differences in monozygotic twins: a retrospective stereophotogrammetric study.

OBJECTIVE: To assess soft tissue differences between monozygotic twins (MZ) for the total face and between facial regions using three-dimensional (3D) stereophotogrammetry and quantitative surface-based 3D deviation analyses. MATERIALS AND METHODS: The study sample consisted of 14 untreated MZ twins (6 males, 8 females, mean age: 14.75 years) from the archive of Marmara University, Department of Orthodontics. The images were taken by the 3dMDface system, and 3dMDvultus software was used for removal of undesired areas and approximation of the images. Then, stereolithography (.stl) format images were superimposed using the best-fit algorithm using 3-matic software. The face was divided into facial thirds, and upper lip and lower lip + chin regions were created. For the comparison, 3D deviation analyses were performed, and a color map and histogram were created. The data were presented as mean deviation, root mean square (RMS), median, and interquartile range. RESULTS: Between the facial thirds, there was no significant difference in soft tissue differences for mean deviation. A statistically significant difference was found between the upper and lower face for the RMS value. For the comparison of upper lip and lower lip + chin region, the only significant difference was for the RMS. When the data were presented as median and interquartile range, there were no statistically significant differences between any facial regions. CONCLUSIONS: Lower facial third and lower lip + chin regions had the greatest differences within MZ twin pairs. The genetic and environmental influences might not be the same for different parts of the face.