Valid 3D surface superimposition references to assess facial changes during growth

Abstract

Currently, the primary techniques applied for the assessment of facial changes over time utilize 2D images. However, this approach has important limitations related to the dimensional reduction and the accuracy of the used data. 3D facial photography has been recently introduced as a risk-free alternative that overcomes these limitations. However, the proper reference areas that should be used to superimpose serial 3D facial images of growing individuals are not yet known. Here, we tested various 3D facial photo superimposition reference areas and compared their outcomes to those of a standard anterior cranial base superimposition technique. We found that a small rectangular area on the forehead plus an area including the middle part of the nose and the lower wall of the orbital foramen provided comparable results to the standard technique and showed adequate reproducibility. Other reference areas that have been used so far in the literature were less reliable. Within the limitations of the study, a valid superimposition reference area for serial 3D facial images of growing individuals is suggested. The method has potential to greatly expand the possibilities of this highly informative, risk free, and easily obtained 3D tool for the assessment of facial changes in growing individuals.

Novel Anterior Cranial Base Area for Voxel-Based Superimposition of Craniofacial CBCTs

“…Therefore, a sample size of 15 CBCT pairs fulfils this purpose successfully. This is also supported from empirical evidence in the current literature [ 9 , 11 , 14 , 16 , 18 , 19 , 21 , 22 , 23 ]. Post hoc power analyses (G*power, version 3.1.9.6) revealed adequate power for comparative statistics (EMACB vs. TACB agreement, power: 97%, a = 0.05; EMACB reproducibility, power: 99%, a = 0.05) to detect an overall difference of 0.5 mm between EMACB and TACB outcomes or between repeated EMACB measurements, which were the primary study outcomes.…”

“…In order to perform accurate assessments when superimposing three-dimensional structures, the superimposition outcomes should be interpreted according to the selected area that serves as the reference for the registration of serial data. The distance between the reference area and the measurement area [ 11 , 16 , 17 ], the anatomical accuracy of the three-dimensional renderings of the reference area, and the area of interest [ 14 , 18 ], as well as the morphological stability of the reference area over time [ 9 , 18 , 19 ], should be considered when selecting the reference area. For voxel-based superimpositions of serial CBCTs, the most widely researched and used area includes the central anterior cranial base structures and extends laterally to those structures, as described in previous investigations [ 20 , 21 , 22 , 23 , 24 ].…”

The effect of orthodontic treatment on smile attractiveness: a systematic review

“…An alternative could be the use of three-dimensional technology to depict the smile in three dimensions. Although 3D photography is widely used to study the face in three dimensions [40,61,62], when it comes to the smile its applicability is limited because the teeth are not depicted well and thus a main feature of the smile appears distorted. All but two of the included studies (Thiruvenkatachari et al [36] and Rizzi et al [35]) removed the colors from the images, before they were evaluated by the raters.…”

Comparison of surface- and voxel-based registration on the mandibular ramus for long-term three-dimensional assessment of condylar remodelling following orthognathic surgery

“…The range of the MAD (SD) between the volumetric measurements and surface distances produced by the two registration techniques was [0.64% (0.61)-12.34% (10. 19)] and [0.02 mm (0.02)-0.34 mm (0.37)], respectively. The largest differences between the two methods were observed in subjects with resorption at the condyle (2.52% (2.11) and 0.34 mm (0.37)), at the coronoid process (7.57% (6.55) and 0.20 mm (0.22)) and at the most distant ramal regions (12.34% (10.19) and 0.14 mm (0.20)) (Table 7 in Supplementary Material 1).…”

“…[14][15][16][17][18] Surface-based registration aligns two 3D surfaces using the iterative closest point algorithm. 19,20 Voxel-based registration uses the grayscale of the voxels to align two 3D volumetric images to the best superimposition. 21,22 Surface-and voxel-based registration have previously been validated for different purposes 19,20,[23][24][25] and were compared for 3D assessment of surgical outcome in adult orthodontic subjects, 26 following orthognathic surgery 27 and for evaluation of growing subjects.…”