Symmetry and Aesthetics in Dentistry

Abstract

Animal bodies in general and faces in particular show mirror symmetry with respect to the median-sagittal plane, with exceptions rarely occurring. Bilateral symmetry to the median sagittal plane of the body also evolved very early. From an evolutionary point of view, it should therefore have fundamental advantages, e.g., more effective locomotion and chewing abilities. On the other hand, the recognition of bilaterally symmetric patterns is an important module in our visual perception. In particular, the recognition of faces with different spatial orientations and their identification is strongly related to the recognition of bilateral symmetry. Maxillofacial surgery and Dentistry affect effective masticatory function and perceived symmetry of the lower third of the face. Both disciplines have the ability to eliminate or mitigate asymmetries with respect to form and function. In our review, we will demonstrate symmetric structures from single teeth to the whole face. We will further describe different approaches to quantify cranial, facial and dental asymmetries by using either landmarks or 3D surface models. Severe facial asymmetries are usually caused by malformations such as hemifacial hyperplasia, injury or other diseases such as Noma or head and neck cancer. This could be an important sociobiological reason for a correlation between asymmetry and perceived disfigurement. The aim of our review is to show how facial symmetry and attractiveness are related and in what way dental and facial structures and the symmetry of their shape and color influence aesthetic perception. We will further demonstrate how modern technology can be used to improve symmetry in facial prostheses and maxillofacial surgery.

A digital workflow for pair matching of maxillary anterior teeth using a 3D segmentation technique for esthetic implant restorations

“…Facial symmetry can greatly improve one’s appearance since facial esthetic subunits are highly sensitive to asymmetry. As seen within the results of a previous study 18 , the bilateral symmetry of facial structures did not imply that two objects in a mirrored pair exactly resembled each other. The differences in eyelid position of > 2 mm, oral commissure of > 3 mm, and brow position of > 3.5 mm were identified as asymmetric pairs 17 .…”

“…Bilateral symmetry of human body structures relative to the mid-sagittal plane is assumed to be beneficial with respect to form and function from an evolutionary standpoint 17 . As with other subunits of the face, left/right symmetry of the dental components has been associated with balanced oral functions and the perception of facial beauty 18 . Symmetry has been considered normal in a healthy face and thus, any facial asymmetry may cause both physiological and psychological problems.…”

Denominator of Cranial Vault Asymmetry Index: Choosing Between Longer and Shorter Diagonal Lengths

“…A total of 30 original articles (Supplemental Table 1, Supplemental Digital Content 1, http://links.lww.com/SCS/E869) matched the inclusion criteria 3–32. There were 10 articles with LD denominators and 20 articles with SD denominators.…”

“…9 On the other hand, the absorbable plate and fixation system [the unsintered hydroxyapatite (uHA)/poly-L-lactic acid (uHA/ PLLA) plate system] have enough strength and stability to fix the segments in both maxillary and mandibular osteotomy such as Le Fort I osteotomy and SSRO. [10][11][12][13][14][15][16] The hybrid and bicortical absorbable plate fixation could show reliable stability with enough strength for class III mandibular setback and class II advancement surgery. 17 However, the comparison in the CT value of ramus bone between advancement surgery for class II and setback surgery for class III using the absorbable plate and screw has not been performed, although there was a study regarding the differences in the morphologic bone healing pattern.…”

Geometric Morphometric Shape Analysis of Mandibular Post-Canine Dentition

“…Symmetry in the dental arches is clinically relevant. The presence of directional asymmetry, i.e., consistently larger or smaller teeth on one side, may be a useful feature for the practice of orthodontics and alignment [30].…”