Measuring 3D shape in orthodontics through geometric morphometrics

Abstract Background Geometric morphometrics (GMM) has been traditionally applied to the field of biology to study developmental differentiations between species. Orthodontics deals with the shape and size of the face and its components. While several tools have been used to measure size, proportions, and relations between anatomical components, shape has been mainly described by esthetic criteria. The purpose of this paper is to present methods to measure shape of 3D orthodontic data, beyond the conventional tools that have been traditionally used in cephalometrics and in facial and dental cast analysis. Findings The authors showcase an example of applying geometric morphometrics to measure palates from scanned dental casts. GMM can be used as a useful tool to describe the three-dimensional shape of surfaces of orthodontic interest. A general introduction to the theoretical principles of how to apply GMM is provided. Conclusions Variability can be measured through the Principal Component Analysis (PCA) and can lead to the identification of shape patterns and sources of variability of the shape, independently from changes in size

Early treatment of Class III malocclusion with RME and facial mask: evaluation of dentoalveolar effects on digital dental casts

Aim: To analyse the dental effects on digital dental casts in subjects with Class III malocclusion treated with bonded Rapid Maxillary Expansion and Facial Mask (RME/FM). Materials and methods: A study group sample (SG) of 29 subjects (13 females and 16 males) and mean age of 7.4 years (SD 1.2 years) was selected. A bonded RME was placed and activated 1/4 of a turn per day until overcorrection of the transverse width. At the end of expansion, patients were given FMs and treated at least to a positive overjet. The SG was compared with a control group (CG) of 21 prepubertal subjects (9 females; 12 males) presenting with normal occlusion and mean age of 7.9 years (SD 1.6 years). For each subject of the SG and CG initial (pretreatment, T1) and final (post-treatment, T2) digital dental casts were available. Significant in between-group differences were tested with the Student's t-test. Results: The transverse dimension of the upper arch was significantly greater in SG vs. CG (IMAW: +2.6 mm; ICAW: +3.1 mm). Anterior arch length and arch depth were significantly smaller in SG when compared with CG (AAL: -3.2 mm, AD: -3.4 mm) at the end of therapy. Conclusion: The orthopaedic treatment with bonded RME/FM produced in subjects treated in the deciduous or early mixed dentition a significant expansion of the maxillary arch and mesialisation of the posterior teeth with a reduction of the arch depth

Effects of pendulum appliance versus clear aligners in the vertical dimension during Class II malocclusion treatment: a randomized prospective clinical trial

BACKGROUND: The aim of the present study was to compare the effects on vertical dentoskeletal dimension produced by Pendulum appliance and Clear Aligners in patients with Class II malocclusion. TRIAL DESIGN: This is a prospective two-arm parallel group randomized clinical trial with 1:1 allocation ratio. METHODS: The Pendulum Group (PG) consisted of 20 patients (15F, 5 M) with a mean age of 17.2 ± 4.3 years. The Clear Aligners Group (CAG) comprised 20 patients (13F, 7 M) with a mean age of 17.2 ± 3.2 years. Distalization’s protocol in PG involved the activation of TMA wires till the achievement of Class I molar relationship. A protocol of sequential distalization was applied in the CAG. For each subject lateral cephalograms have been analyzed before treatment (T1) and at the end of the therapy (T2). Descriptive statistics and statistical between-group comparisons (PG vs CAG) were calculated for the craniofacial starting forms at T1 and for the T2–T1 changes. Statistical between-group comparisons for the T2–T1 changes were performed with independent samples t-tests (P < 0.05). RESULTS: The PG showed significantly greater increases in SN^GoGn° when compared with CAG (+ 2.1 and − 0.3 degrees, respectively). Clockwise rotation of the occlusal plane with significantly greater increase of SN^POccl angle was observed in PG (+ 2.8 degrees) when compared with CAG (− 4.2 degrees). The PG revealed a significant increase in the N-Me variable with a mean change of + 4.4 mm compared to the CAG with mean values of − 1.2 mm. The PG showed an increase in the ArGo^GoMe angle (+ 0.7° degrees) compared to the CAG (− 3.4° degrees). The PG showed significantly greater increases in both maxillary and mandibular first molar to palatal plane (+ 1.3 and + 2.1 mm, respectively) when compared with CAG (− 0.9 and − 0.2 mm, respectively). CONCLUSIONS: Upper molar distalization with clear aligners represents a valid alternative to non-extraction treatment of Class II malocclusion, reducing the extrusion of maxillary first molars and improving the management of the occlusal plane and vertical dimension. Trial registration: ClinicalTrials.gov, NCT05298280. Registered 28 March 2022—Retrospectively registered, https://clinicaltrials.gov

The efficacy and predictability of maxillary first molar derotation with invisalign: a prospective clinical study in growing subjects

To analyze the derotation of maxillary mesio-rotated first permanent molars in subjects with Class II edge-to-edge dental malocclusion in mixed dentition treated with Invisalign Clear Aligners (CA). In total, 36 patients (16 males, 20 females, 9.9 &plusmn; 1.9 years) treated with CA are enrolled from the Department of Orthodontics. Inclusion criteria are the following: Caucasian ancestry, mixed dentition, molar Class II edge-to-edge, no tooth/craniofacial anomalies, no caries/periodontal diseases. Pre-treatment (T1) and post-treatment (T2) digital casts, and final ClinCheck representations (T2ClinCheck) are acquired. The Henry&rsquo;s angle (HA) is used to assess maxillary first molars rotation. The molars with an HA &gt; 11&deg; are taken (53 teeth). Five measurements are performed at T1, T2, and T2ClinCheck: Henry&rsquo;s angle (HA), mesiobuccal-expansion (MBE), distobuccal-expansion (DBE), mesiobuccal-sagittal (MBS), and distobuccal-sagittal (DBS). A paired t-test was used to compare T2-T1 and T2ClinCheck-T2. The T2-T1 shows a distal-rotation (difference &minus;6.3&deg;) with an expansion of 2.2 mm for MBE and 1.5 mm for DBE. At T2, the mesiobuccal cusps show a distal movement of 1.0 mm and the distobuccal cusps of 0.9 mm. The HA&rsquo;s T2ClinCheck-T2 difference is &minus;4.2&deg;. In the sagittal plane, the difference is 0.9 mm for the MBS and 0.7 mm for the DBS. The expansion showed the highest predictability (60% HA, 52.6% MBS, and 56.25% DBS). The CA effectively produces an arch expansion and upper molars&rsquo; distal rotation. Upper molar derotation provides a 1 mm of gain in arch perimeter and occlusal improvement

Correction to: Mandibular response after rapid maxillary expansion in class II growing patients: a pilot randomized controlled trial

In the publication of this article (1) there is an error in the Methods section.https://deepblue.lib.umich.edu/bitstream/2027.42/144777/1/40510_2018_Article_231.pd

Morphometric covariation between palatal shape and skeletal pattern in Class II growing subjects

Objectives To evaluate the patterns of covariation between palatal and craniofacial morphology in Class II subjects in the early mixed dentition by means of geometric morphometrics. Methods A cross-sectional sample of 85 Class II subjects (44 females, 41 males; mean age 8.7 years ± 0.8) was collected retrospectively according to the following inclusion criteria: European ancestry (white), Class II skeletal relationship, Class II division 1 dental relationship, early mixed dentition, and prepubertal skeletal maturation. Pre-treatment digital 3D maxillary dental casts and lateral cephalograms were available. Landmarks and semilandmarks were digitized (239 on the palate and 121 on the cephalogram) and geometric morphometric methods (GMM) were applied. Procrustes analysis and principal component analysis (PCA) were performed to reveal the main patterns of palatal shape and craniofacial skeletal shape variation. Two-block partial least squares analysis (PLS) assessed patterns of covariation between palatal morphology and craniofacial morphology. Results For the morphology of the palate, the first principal component (PC1) described variation in all three dimensions. For the morphology of the craniofacial complex, PC1 showed shape variation mainly in the vertical direction. Palatal shape and craniofacial shape covaried significantly (RV coefficient: 0.199). PLS1 accounted for more than 64 per cent of total covariation and related divergence of the craniofacial complex to palatal height and width. The more a Class II subject tended towards high-angle divergence, the narrower and higher was the palate. Conclusions Class II high-angle patients tended to have narrower and higher palates, while Class II low-angle patients were related to wider and more shallow palates

Mandibular response after rapid maxillary expansion in class II growing patients: a pilot randomized controlled trial

Abstract Background The aim of this pilot randomized controlled trial (RCT) was to evaluate the sagittal mandibular response induced by rapid maxillary expansion (RME) therapy in mixed dentition patients with class II malocclusion, comparing the effects of bonded RME and banded RME with a matched untreated class II control group. Methods This RCT was designed in parallel with an allocation ratio of 1:1:1. The sample consisted of 30 children with a mean age of 8.1 ± 0.6 years who were randomly assigned to three groups: group 1 treated with bonded RME, group 2 treated with banded RME, and group 3 the untreated control group. All patients met the following inclusion criteria: early mixed dentition, class II molar relationship, transverse discrepancy ≥ 4 mm, overjet ≥ 5 mm, and prepubertal skeletal maturity stage (CS1–CS2). The expansion screw was activated one quarter of a turn per day (0.25 mm) until overcorrection was reached. For each subject, lateral cephalograms and plaster casts were obtained before treatment (T1) and after 1 year (T2). A randomization list was created for the group assignment, with an allocation ratio of 1:1:1. The observer who performed all the measurements was blinded to group assignment. The study was single-blinded in regard to statistical analysis. Results RME was effective in the correction of maxillary deficiency. Class II patients treated with both types of RME showed no significant improvement of the anteroposterior relationship of the maxilla and the mandible at both skeletal and occlusal levels. The acrylic splint RME had significant effects on reducing the skeletal vertical dimension and the gonial angle. Conclusions The orthopedic expansion did not affect the sagittal relationship of class II patients treated in the early mixed dentition when compared with the untreated control group. Additional studies with a larger sample are warranted to elucidate individual variations in dento-skeletal mandibular response to the maxillary expansion protocol in class-II-growing patients. Trial registration ClinicalTrials.gov NCT03159962