Fluctuating asymmetry of the normal facial skeleton

Gateño, Jaime; Jones, Terry; Shen, Steve Guofang; Chen, Ken-Chung; Jajoo, Aarti; Kuang, Tianshu; English, Jeryl D.; Nicol, Matthew; Teichgraeber, John F.; Xia, James J.

doi:10.1016/j.ijom.2017.10.011

Cited by 21 publications

(10 citation statements)

References 27 publications

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“…First, that body and face size are allometrically related in adults and that facial FA is a by‐product of individual growth. In contrast to previous studies (e.g., Gateño et al, 2018; Mitteroecker et al, 2013), the results were compatible, with high uncertainty, with an effect close to zero. These results suggest that more discussion is needed on the empirical causal model derived for this hypothesis.…”

Section: Discussioncontrasting

confidence: 99%

Formal models for the study of the relationship between fluctuating asymmetry and fitness in humans

Farrera

2022

American Journal of Biological Anthropology

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Objectives To evaluate three of the main verbal models that have been proposed to explain the relationship between fluctuating asymmetry and fitness in humans: the “good genes,” the “good development,” and the “growth” hypotheses. Materials and Methods A formal model was generated for each verbal model following three steps. First, based on the literature, a theoretical causal model and the theoretical object of inquiry were outlined. Second, an empirical causal model and the targets of inference were defined using observational data of facial asymmetries and life‐history traits related to fitness. Third, generalized linear models and causal inference were used as the estimation strategy. Results The results suggest that the theoretical and empirical assumptions of the “good genes” hypothesis should be reformulated. The results were compatible with most of the empirical assumptions of “the good development” hypothesis but suggest that further discussion of its theoretical assumptions is needed. The results were less informative about the “growth” hypothesis, both theoretically and empirically. There was a positive association between facial fluctuating asymmetry and the number of offspring that was not compatible with any of the empirical causal models evaluated. Conclusions Although the three hypotheses focus on different aspects of the link between asymmetry and fitness, their overlap opens the possibility of a unified theory on the subject. The results of this study make explicit which assumptions need to be updated and discussed, facilitating the advancement of this area of research. Overall, this study elucidates the potential benefit of using formal models for theory revision and development.

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Section: Discussioncontrasting

confidence: 99%

Formal models for the study of the relationship between fluctuating asymmetry and fitness in humans

Farrera

2022

American Journal of Biological Anthropology

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“…Furthermore, we exhibited that even the included normal individuals presented with a certain degree of facial asymmetry as revealed by both the 2D and 3D photogrammetric methods. As this finding has widely been demonstrated for normal populations 34,46 , valid deductions could be made from normal-related comparisons. Different from mid-face or nasolabial measurement-based outcome investigations 35,36,47 , in this study we addressed particularly the lower face region.…”

Section: Lateral Lower Chin N (%)supporting

confidence: 55%

Outcome of facial contour asymmetry after conventional two-dimensional versus computer-assisted three-dimensional planning in cleft orthognathic surgery

Hsu

Denadai

Pai

et al. 2020

Sci Rep

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Computer-assisted 3D planning has overcome the limitations of conventional 2D planning-guided orthognathic surgery (OGS), but difference for facial contour asymmetry outcome has not been verified to date. This comparative study assessed the facial contour asymmetry outcome of consecutive patients with unilateral cleft lip and palate who underwent 2D planning (n = 37)-or 3D simulation (n = 38)-guided OGS treatment for correction of maxillary hypoplasia and skeletal Class III malocclusion between 2010 and 2018. Normal age-, gender-, and ethnicity-matched individuals (n = 60) were enrolled for comparative analyses. 2D (n = 60, with 30 images for each group) and 3D (n = 43, with 18 and 25 images for 2D planning and 3D simulation groups, respectively) photogrammetric-based facial contour asymmetry-related measurements were collected from patients and normal individuals. The facial asymmetry was further verified by using subjective perception of a panel composed of 6 blinded raters. On average, the facial contour asymmetry was significantly (all p < 0.05) reduced after 3D virtual surgery planning for all tested parameters, with no significant differences between post-OGS 3D simulation-related values and normal individuals. No significant differences were observed for pre-and post-OGS values in conventional 2D planning-based treatment, with significant (all p < 0.05) differences for all normal individuals-related comparisons. This study suggests that 3D planning presents superior facial contour asymmetry outcome than 2D planning.Orthognathic surgery (OGS) plays a key role for successful management of a myriad of facial deformities associated with malocclusion, with facial asymmetry feature being most frequently associated with skeletal class III malocclusion 1-3 . Particularly, patients with unilateral cleft lip and palate differ from the noncleft population, because they have a congenital orofacial defect compromising both the bone and soft tissues on the lesion side 4-6 , which may be expressed as facial asymmetry 7-15 . Skeletal mature patients with clefts frequently presents with maxillomandibular disharmony (maxillary hypoplasia and skeletal class III malocclusion) which requires OGS treatment 7-15 . As residual facial asymmetry after OGS treatment may negatively impact patients' perceptions about outcome requiring further revisionary surgical interventions [16][17][18][19] , the significance of preoperative prediction of this deformity should not be underestimated 15,16,20 . Therefore, it is of paramount that an accurate diagnosis of asymmetry is accomplished preoperatively for that a precise surgical planning and execution is performed 7,15,16,20 .In this setting, OGS planning has evolved over the past decades 15-24 . Traditionally, OGS planning has been constructed on two-dimensional (2D) cephalometry, 2D photographic analysis, articulators, and dental models 21,22 . However, this planning modality presents limitations for challenging clinical scenarios such as patients with clefts associated with malocclusion a...

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“…[19][20][21][22] However, these studies reported the symmetry of volume and measurement values such as the angle only on unilateral sides, and the reference plane of the symmetry was different in each study. 23,24 Furthermore, threedimensional anatomical and locational symmetry between both sides of the orbits has not been studied. These are crucial factors, especially in the orbital area, because they are directly related to the accuracy of the mirroring technology and surgical outcomes.…”

Section: Discussionmentioning

confidence: 99%

Is the Mirroring Technology Reliable in the Use of Computer-Aided Design for Orbital Reconstruction? Three-Dimensional Analysis of Asymmetry in the Orbits

Kang

Shin

2022

Plastic &Amp; Reconstructive Surgery

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Background: Reconstruction of the orbital area remains a challenge in many cases. The recently introduced mirroring technology provides surgeons with patient-specific information for accurate orbital reconstruction; its premise is that the three-dimensional anatomy of craniofacial bone is symmetric. The purpose of this study was to verify this premise of the mirroring technology by assessing three-dimensional asymmetry. Methods: Facial computed tomographic data of 104 patients were imported into iPlan software. Four reference points (i.e., zygomaticofrontal suture, frontomaxillary suture, infraorbital foramen, and optic canal) were set, and the three-dimensional distances from these points to the anterior nasal spine on the mirroring plane were calculated. In addition, the orbital cavity volume and the three-dimensional distances from point optic canal to the other reference points were calculated for the assessment of the orbit anatomy. Three plastic surgeons performed these processes independently. Results: No statistically significant difference was found in the three-dimensional distances between anterior nasal spine and the four reference points bilaterally. Also, no statistically significant difference in the three-dimensional distances between the point representing the optic canal and other reference points was detected bilaterally. Orbital cavity volume showed a mild asymmetry, but the discrepancy was acceptable for computer-aided design applications. For all reference points, the maximum value of the 95 percent CI was less than 1.4 mm. Conclusions:The three-dimensional location of the orbits and the three-dimensional anatomy of the orbit were symmetric. Thus, the mirroring technology could be a reliable first step in computer-aided design, computer-assisted surgery, and navigation-assisted surgery.

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Fluctuating asymmetry of the normal facial skeleton

Cited by 21 publications

References 27 publications

Formal models for the study of the relationship between fluctuating asymmetry and fitness in humans

Formal models for the study of the relationship between fluctuating asymmetry and fitness in humans

Outcome of facial contour asymmetry after conventional two-dimensional versus computer-assisted three-dimensional planning in cleft orthognathic surgery

Is the Mirroring Technology Reliable in the Use of Computer-Aided Design for Orbital Reconstruction? Three-Dimensional Analysis of Asymmetry in the Orbits

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