The Quantification of Tooth Displacement

By using reference points from a single pixel marker placed at the center point of the cuspid teeth and the center point on each of the incisor teeth, a polynomial curve was generated as a native curve for each dental arch studied. The polynomial curve generated from actual tooth position in each arch provides the forensic odontologist with another reference point that is quantifiable. The study represents that individual characteristics, such as tooth displacement, can be quantified in a simple, reliable, and repeatable format

Changes in the midpalatal and pterygopalatine sutures induced by micro-implant-supported skeletal expander, analyzed with a novel 3D method based on CBCT imaging.

BackgroundMini-implant-assisted rapid palatal expansion (MARPE) appliances have been developed with the aim to enhance the orthopedic effect induced by rapid maxillary expansion (RME). Maxillary Skeletal Expander (MSE) is a particular type of MARPE appliance characterized by the presence of four mini-implants positioned in the posterior part of the palate with bi-cortical engagement. The aim of the present study is to evaluate the MSE effects on the midpalatal and pterygopalatine sutures in late adolescents, using high-resolution CBCT. Specific aims are to define the magnitude and sagittal parallelism of midpalatal suture opening, to measure the extent of transverse asymmetry of split, and to illustrate the possibility of splitting the pterygopalatine suture.MethodsFifteen subjects (mean age of 17.2 years; range, 13.9-26.2 years) were treated with MSE. Pre- and post-treatment CBCT exams were taken and superimposed. A novel methodology based on three new reference planes was utilized to analyze the sutural changes. Parameters were compared from pre- to post-treatment and between genders non-parametrically using the Wilcoxon sign rank test. For the frequency of openings in the lower part of the pterygopalatine suture, the Fisher's exact test was used.ResultsRegarding the magnitude of midpalatal suture opening, the split at anterior nasal spine (ANS) and at posterior nasal spine (PNS) was 4.8 and 4.3 mm, respectively. The amount of split at PNS was 90% of that at ANS, showing that the opening of the midpalatal suture was almost perfectly parallel antero-posteriorly. On average, one half of the anterior nasal spine (ANS) moved more than the contralateral one by 1.1 mm. Openings between the lateral and medial plates of the pterygoid process were detectable in 53% of the sutures (P < 0.05). No significant differences were found in the magnitude and frequency of suture opening between males and females. Correlation between age and suture opening was negligible (R 2 range, 0.3-4.2%).ConclusionsMidpalatal suture was successfully split by MSE in late adolescents, and the opening was almost perfectly parallel in a sagittal direction. Regarding the extent of transverse asymmetry of the split, on average one half of ANS moved more than the contralateral one by 1.1 mm. Pterygopalatine suture was split in its lower region by MSE, as the pyramidal process was pulled out from the pterygoid process. Patient gender and age had a negligible influence on suture opening for the age group considered in the study

3D mandibular superimposition: Comparison of regions of reference for voxel-based registration

The aim was to evaluate three regions of reference (Björk, Modified Björk and mandibular Body) for mandibular registration testing them in a patients' CBCT sample.Mandibular 3D volumetric label maps were built from CBCTs taken before (T1) and after treatment (T2) in a sample of 16 growing subjects and labeled with eight landmarks. Registrations of T1 and T2 images relative to the different regions of reference were performed, and 3D surface models were generated. Seven mandibular dimensions were measured separately for each time-point (T1 and T2) in relation to a stable reference structure (lingual cortical of symphysis), and the T2-T1 differences were calculated. These differences were compared to differences measured between the superimposed T2 (generated from different regions of reference: Björk, Modified Björk and Mandibular Body) over T1 surface models. ICC and the Bland-Altman method tested the agreement of the changes obtained by nonsuperimposition measurements from the patients' sample, and changes between the overlapped surfaces after registration using the different regions of reference.The Björk region of reference (or mask) did work properly only in 2 of 16 patients. Evaluating the two other masks (Modified Björk and Mandibular body) on patients' scans registration, the concordance and agreement of the changes obtained from superimpositions (registered T2 over T1) compared to results obtained from non superimposed T1 and T2 separately, indicated that Mandibular Body mask displayed more consistent results.The mandibular body mask (mandible without teeth, alveolar bone, rami and condyles) is a reliable reference for 3D regional registration

Evaluation of natural mandibular shape asymmetry : an approach by using elliptical Fourier analysis

Q2Q1Objectives: The purpose of this study was to demonstrate that asymmetry is a natural occurring phenomenon in the mandibular shape by using elliptical Fourier analysis. Methods: 164 digital orthopantomographs from Colombian patients of both sexes aged 18 to 25 years were collected. Curves from left and right hemimandible were digitized. An elliptical Fourier analysis was performed with 20 harmonics. In the general sexual dimorphism a principal component analysis (PCA) and a hotelling T2 from the multivariate warp space were employed. Exploratory analysis of general asymmetry and sexual dimorphism by side was made with a Procrustes Fit. A non-parametric multivariate analysis of variance (MANOVA) was applied to assess differentiation of skeletal classes of each hemimandible, and a Procrustes analysis of variance (ANOVA) was applied to search any relation between skeletal class and side in both sexes. Results: Significant values were found in general asymmetry, general sexual dimorphism, in dimorphism by side (p < 0.0001), asymmetry by sex, and differences between Class I, II, and III (p < 0.005). However, a relation of skeletal classes and side was not found. Conclusions: The mandibular asymmetry by shape is present in all patients and should not be articulated exclusively to pathological processes, therefore, along with sexual dimorphism and differences between skeletal classes must be taken into account for improving mandibular prediction systems.http://scienti.colciencias.gov.co:8081/cvlac/visualizador/generarCurriculoCv.do?cod_rh=0001545804Revista Nacional - Indexad

Unilateral condylar hyperplasia: a thee-dimensional CBCT morphometric and volumetric evaluation of mandibular condyle by open-source softwares : Hiperplasia condilar unilateral: Evaluación morfométrica y volumétrica en TCHC tridimensional del cóndilo mandibular mediante softwares de código abierto

SUMMARY: Unilateral condylar hyperplasia (UCH) is an alteration of the mandibular condyle growth. The aim of this study was to evaluate condyle volume, surface area, and Morphological Index (MI) differences between the affected condyle and an unaffected one in patients with UCH, evaluated through 3D reconstructions cone beam computed tomography (CBCT) images by two open-source softwares. A retrospective cross-sectional study of 16 patients with a certain UCH, 9 females and 7 males with mean age 25.13 ± 6.8 years was made. The image obtained from the CBCT of each condyle were reconstructed using the open-source software 3D SLICER 4.6 ®. The volumetric and area measurements of the 3D reconstruction of the mandibular condyle were made using the open-source software NETFABB basic 5.0 ®. The mean condylar volume of the hyperplastic condyles was 2.07 ± 1.51 cm3 and the non-hyperplastic condyles was 1.16 ± 0.82 cm3 (p&lt;0.05). The mean area surface of the hyperplastic condyle was 11.77 ± 3.71 cm2 and the non-hyperplasic condyle mean was 8.05 ± 2.17 cm2 (p &lt; 0.05). The mean area surface difference was 3.72 ± 3.57 cm2 (28.0 %). The MI of the hyperplastic condyle was 1.8 ± 0.3 mm and the non-affected condyle was 1.3 ± 0.6 mm (p &lt; 0.05). The use of open-source software for 3D reconstruction with manual segmentation for evaluation of the volume and the condylar surface is a valid tool available to the clinic in the diagnosis and monitoring of patients with condylar hyperplasia. © 2021, Universidad de la Frontera. All rights reserved

Towards an early 3D-diagnosis of craniofacial asymmetry by computing the accurate midplane: A PCA-based method

Background and objective: Craniofacial asymmetry is a common growth disorder often caused by unilateral chewing. Although an early orthodontic treatment would avoid surgical procedures later in life, the uncertainty of defining the accurate sagittal midplane potentially leads to misdiagnosis and therefore inaccurate orthodontic treatment plans. This novel study aims to 3D-diagnose craniofacial complex malformations in children with unilateral crossbite (UXB) considering a midplane which compensates the asymmetric morphology. Methods: The sagittal midplane of 20 children, fifteen of whom exhibited UXB, was computed by a PCA- based method which compensates the asymmetry mirroring the 3D models obtained from cone-beam computed tomography data. Once determined, one side of the data was mirrored using the computed midplane to visualize the malformations on the hard and soft tissues by 3D-computing the distances between both halves. Additionally, 31 skull’s landmarks were manually placed in each model to study the principal variation modes and the significant differences in the group of subjects with and without UXB through PCA and Mann-Whitney U test analyses respectively. Results: Morphological 3D-analysis showed pronounced deformities and aesthetic implications for patients with severe asymmetry (jaw deviation > 0.8 mm) in whole craniofacial system, while initial signs of asymmetry were found indistinctly in the mandible or maxilla. We detected significant ( p < 0.05) malformations for example in mandibular ramus length (0.0086), maxillary palate width (0.0481) and condylar head width (0.0408). Craniofacial malformations increased the landmarks’ variability in the group of patients with UXB over the control group requiring 8 variation modes more to define 99% of the sample’ variability. Conclusions: Our findings demonstrated the viability of early diagnosis of craniofacial asymmetry through computing the accurate sagittal midplane which compensates the individual’s asymmetrical morphology. Furthermore, this study provides important computational insights into the determination of craniofacial deformities which are caused by UXB, following some empirical findings of previous clinical studies. Hence, this computational approach can be useful for the development of new software in craniofacial surgery or for its use in biomedical research and clinical practice

Automated Planning with Multivariate Shape Descriptors for Fibular Transfer in Mandibular Reconstruction

Objective: This paper introduces methods to automate preoperative planning of fibular segmentation and placement for mandibular reconstruction with fibular flaps. Methods: Preoperative virtual planning for this type of surgery has been performed by manual adjustment of many parameters, or based upon a single feature of the reconstruction. We propose a novel planning procedure formulated as a non-convex minimization problem of an objective function using the multilateral shape descriptors. Results: A retrospective study was designed and 120 reconstruction plans were reproduced using computed tomography images with oral surgeons. The proposed automated planning model was quantitatively compared with both the existing model and the surgeons’ plans. Conclusion: The results show that the developed framework attains stable automated planning that agrees with the surgeons’ decisions. Significance: This method addresses trade-off problems between symmetric reconstruction and restoration of the native contour of the mandible

Clinical application of a 3-dimensional morphometric apparatus for diagnosis and treatment of a Class III patient with facial asymmetry : A pilot study

This article demonstrated the usefulness of a non-contact 3-dimensional (3D) morphometric apparatus in orthodontic diagnosis and treatment evaluation. A female patient, 23 years 6 months of age, had a Class III malocclusion with mandibular deviation. The 3D images taken by a 3D morphometric apparatus figured out her protrusive chin of 6 mm on the deviation side compared to the non-deviation side, and showed a possibility of orthognathic surgery. Before starting of orthodontic treatment, a diagnostic splint was used for 2 months to determine her proper mandibular position. The 3D images retaken for quantitative evaluation showed decrease of the mandibular protrusion by approximately 3 mm, and improvement of facial asymmetry. Then, we decided to treat the patient without orthognathic surgery. After 18 months of active orthodontic treatment with miniscrew anchorage, the mandibular deviation was improved and an acceptable occlusion was achieved. The 3D images at posttreatment demonstrated significant decrease of chin protrusion on the deviation side, and improvement of facial asymmetry. In conclusion, a 3D morphometric apparatus could provide quantitative data of facial asymmetry and chin protrusion and contributed decision making process of treatment planning in a patient with facial asymmetry

3D superimposition of craniofacial imaging—The utility of multicentre collaborations

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/149360/1/ocr12281.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/149360/2/ocr12281_am.pd