Evaluation of palate morphology in patients treated with leaf expander and hyrax expander: A geometric morphometric analysis.

OBJECTIVE: The aim of this study was to evaluate changes in shape of the palatal vault after maxillary expansion with hyrax expander (HE) and leaf expander (LE), using 3D Geometric Morphometric Analysis. SETTING AND SAMPLE POPULATION: Overall, 250 patients (110 M, 140 F) with maxillary transverse deficiency were selected for this study. In this study, 127 subjects were treated with HE, 123 with LE. MATERIALS AND METHODS: Digital dental models were obtained pre-treatment (T0) and after 12 months from the cementation of the device (T1) and processed by means of a digital scanner. Linear and morphometric analyses were conducted to determine the effects of each appliance on dental measurements and palatal shape, and a multiple linear regression was performed to analyse the influence of anchorage and appliance type on final shape. RESULTS: Morphometric analysis showed that there was a lowering of the palatal vault in the HE group, while in the LE group it remained unchanged: the difference in palatal shape at time T0 and T1 was statistically significant in both treatments (HE vs. LE). In the HE group, the change in shape also included the upper part of the palatal vault in the vertical dimension, while in the LE group the change in shape interested mainly palatal shelves and the lower portion of the palate. CONCLUSIONS: Both LE and HE produce clinically significant changes in the morphology of the palatal vault.

Morphologic predictors of mandibular changes induced by Sander's Bite Jumping Appliance.

AIM: This study aimed to identify pretreatment cephalometric variables as possible predictors of the mandibular length increase in Class II patients with mandibular retrusion, treated by means of the Bite Jumping Appliance (BJA). MATERIALS AND METHODS: Forty-three subjects (22 males and 21 females) with Class II malocclusion, treated with a BJA, were selected on the basis of the following inclusion criteria: full Class II molar relationship, Overjet (OVJ) ≥ 6 mm and a skeletal Class II malocclusion with mandibular retrusion at the start of the treatment (T0); cervical vertebral maturation stage 2 or 3 at time 0 (T0). The following mandibular structural features were measured on lateral cephalograms at time 0 and time 1 (15 months of treatment): the width and height of the mandibular symphysis and its width/height ratio, the width and height of the mandibular ramus and its width/height ratio, the antegonial notch depth and the Condilion-Gonion-Menton (Co-Go-Me) angle. Post-treatment changes were assessed by Pancherz's cephalometric analysis, evaluating the increases in mandibular length. A regression statistical model was used to test the association between morphologic variables and mandibular length changes. RESULTS: At T1, a significant increase in mandibular length (7.1 + 3.4 mm, p < .001) was measured. A significant negative association between the pretreatment Co-Go-Me angle and mandibular length change was found (p < .05). IMPA angle was negatively associated with mandibular length change. All the others morphological feature were not statistically related to mandibular length change. CONCLUSION: Co-Go-Me angle and IMPA angle at T0 can be used as predictors for mandibular response to the treatment with BJA.

Palatal changes in crossbite patients treated with rapid maxillary expansion vs untreated ones: A geometric morphometric study.

OBJECTIVE: The present study aimed to analyse palatal changes due to rapid maxillary expansion (RME) by using modern geometric morphometric analysis (GMA) on 3D models. SETTINGS AND SAMPLE POPULATION: Forty children with posterior crossbite and maxillary deficiency were selected for this study. Twenty children were treated with RME (mean age 7.4 ± 0.8 years), whereas 20 children were not treated (mean age 7.2 ± 1.1 years). MATERIALS AND METHODS: In the treated group, RME screw was activated until overcorrection was achieved and the RME appliance remained in place for 11 months. Digital dental casts were recorded before treatment and 1 year after the end of active treatment. GMA was performed to compare shape and dimensional variations among groups (between-group principal component analysis). RESULTS: All children in the treated group achieved crossbite correction. None of the control group children achieved crossbite self-correction. No significant shape and dimensional changes were noted in the control group after 1 year. On the other hand, significant shape and dimensional changes were noted in the treated group after 1 year (P < .05). Most of the shape changes in the treated group were similar but more pronounced compared to those observed in the control group. All major changes in palatal morphology occurred on the lateral sides of the palatal vault (widening) and at the height (shortening). Some shape changes were observed in the treated group alone. CONCLUSIONS: Application of GMA to evaluate the effects of RME in crossbite patients revealed significant changes in palatal morphology compared with the absence of changes in the control group.

A Semi-Automatic Method on a Small Italian Sample for Estimating Sex Based on the Shape of the Crown of the Maxillary Posterior Teeth.

Teeth are known to be reliable substrates for human identification and are endowed with significant sexual dimorphism not only in the size but also in the shape of the crowns. In the preliminary phase of our study (already published in 2021), a novel sex estimation method based on dental morphometric geometric (GMA) analysis combined with the artificial neural network (ANN) was developed and validated on a single dental element (first upper premolar) with an accuracy rate of 80%. This study aims to experiment and validate the combination of GMA-ANN on the upper first and second left premolars and the upper left first molar to obtain a reliable classification model based on the sexual dimorphic traits of multiple maxillary teeth of Caucasian Italian adults (115 males and 115 females). A general procrustes superimposition (GPS) and principal component analysis (PCA) were performed to study the shape variance between the sexes and to reduce the data variations. The "set-aside" approach was used to validate the accuracy of the proposed ANN. As the main findings, the proposed method correctly classified 94% of females and 68% of males from the test sample and the overall accuracy gained was 82%, higher than the odontometric methods that similarly consider multiple teeth. The shape variation between male and female premolars represents the best dimorphic feature compared with the first upper molar. Future research could overcome some limitations by considering a larger sample of subjects and experimenting with the use of computer vision for automatic landmark positioning and should verify the present evidence in samples with different ancestry.

Three-Dimensional Dental Analysis for Sex Estimation in the Italian Population: A Pilot Study Based on a Geometric Morphometric and Artificial Neural Network Approach.

Dental dimorphism can be used for discriminating sex in forensic contexts. Geometric morphometric analysis (GMA) allows the evaluation of the shape and size, separately, of uneven 3D objects. This study presents experiments using a novel combination of GMA and an artificial neural network (ANN) for sex classification, applied to premolars of Caucasian Italian adults (50 females and 50 males). General Procrustes superimposition (GPS) and the partial least square (PLS) method were performed, respectively, to study the shape variance between sexes and to eliminate landmark variations. The "set-aside" approach was used to assess the accuracy of the proposed neural networks. As the main findings of the pilot study, the proposed method applied to the first upper premolar correctly classified 90% of females and 73% of males of the test sample. The accuracy was 0.84 and 0.80 for the training and test samples, respectively. The sexual dimorphism resulting from GMA was low, although statistically significant. GMA combined with the ANN demonstrated better sex classification ability than previous odontometric or dental morphometric methods. Future research could overcome some limitations by considering a larger sample of subjects and other kinds of teeth and experimenting with the use of computer vision for automatic landmark positioning.

Volumetric analysis of cleft lip deformity using 3D stereophotogrammetry.

PURPOSE: To quantify and compare pre-operative and post-operative volumetric adjustments of the upper lip tissues in patients with cleft lip. METHODS: The authors performed an anthropometric study and a quantitative analysis of the differences based on three-dimensional morphology of the nasolabial area. Twenty facial images using the three-dimensional stereophotogrammetry were taken from ten selected subjects on two separate occasions, sitting in natural head position. Facial landmarks were marked and measurements recorded, in order to calculate the volumetric adjustments in the soft tissues of the upper lip, comparing the preoperative and postoperative results. Student test and p-Value were performed for statistical analysis. RESULTS: The analysis of the 3D images showed variability with the pre- and postoperative volumes of the nasolabial area with: an increase of upper lip volume all patients; a complete view of the severity in the preoperative; and an improvement of the appearance in the postoperative. The amount of increase of the upper lip volume was established about 29,7%. For all measurements, the variability between pre- and post-operative was significant (p < 0.01). CONCLUSION: The 3D stereophotogrammetry technique allows a detailed preoperative evaluation and an accurate assessment of the surgical outcomes. The study provides a value of volumetric variation of the upper lip in individuals with cleft lip. KEY WORDS: Cleft lip, Nasolabial area, 3D Morphological Analysis, 3D Stereophotogrammetry, Upper lip volume.