Search Results (3)

Background: This retrospective in vivo study evaluated the trueness and precision of two digital intraoral scanners—Dentsply Sirona Primescan and Medit i900—, both with and without two variants of the novel Scan Ladder aids, and compared their performance to a new intraoral photogrammetry scanner (Shining 3D Elite). Methods: Data from ten edentulous patients, previously collected during routine clinical treatment, were analyzed using a master STL generated from traditional impression casts as the reference. A custom positional change calculator and comprehensive statistical analysis were used to assess scanner accuracy. Results: The findings demonstrated that the use of the Scan Ladder significantly enhanced the overall accuracy of both intraoral scanners, showing no statistically significant differences when compared to the intraoral photogrammetry system. Conclusions: These results indicate that the Scan Ladder improves the performance of conventional intraoral scanners and suggests that the Shining 3D Elite intraoral photogrammetry scanner is a reliable alternative to extraoral photogrammetry for edentulous cases. Further research, with a larger and more diverse cohort, is warranted to validate and expand upon these findings. Full article

Positional cranial deformities are a common finding in toddlers, yet differentiation from craniosynostosis can be challenging. The aim of this study was to train convolutional neural networks (CNNs) to classify craniofacial deformities based on 2D images generated using photogrammetry as a radiation-free imaging technique. A total of 487 patients with photogrammetry scans were included in this retrospective cohort study: children with craniosynostosis (n = 227), positional deformities (n = 206), and healthy children (n = 54). Three two-dimensional images were extracted from each photogrammetry scan. The datasets were divided into training, validation, and test sets. During the training, fine-tuned ResNet-152s were utilized. The performance was quantified using tenfold cross-validation. For the detection of craniosynostosis, sensitivity was at 0.94 with a specificity of 0.85. Regarding the differentiation of the five existing classes (trigonocephaly, scaphocephaly, positional plagiocephaly left, positional plagiocephaly right, and healthy), sensitivity ranged from 0.45 (positional plagiocephaly left) to 0.95 (scaphocephaly) and specificity ranged from 0.87 (positional plagiocephaly right) to 0.97 (scaphocephaly). We present a CNN-based approach to classify craniofacial deformities on two-dimensional images with promising results. A larger dataset would be required to identify rarer forms of craniosynostosis as well. The chosen 2D approach enables future applications for digital cameras or smartphones. Full article

Archaeological monuments all over the world face problems of conservation and maintenance due to natural events and processes as well as human intervention, all of which lead to their alteration and deterioration. In particular, monuments and sites that have been excavated and left exposed to the elements experience decay, which would have taken centuries prior to excavation, in just a few years when left unprotected. Thus, the necessity to detect and observe changes over time becomes paramount. Legacy data and, in particular, retrospective photogrammetric modeling, are vital tools in this process. In this work we compare two photogrammetric 3D models of the Omega House, in the Athenian Agora, to assess how much the site has changed between the time of its first excavation in 1972 and its current state. Constructive Solid Geometry (CSG) is utilized to perform Boolean operations. Additionally, distance and volume calculations are performed. The software CloudCompare was used for this work. Overall, the state of Omega House monument proves to have been preserved from 1972 to 2017, except for certain differences that are highlighted as follows: The central north part of the monument in the model 2017 presents increased volume per 7.86% in comparison with the model 1972. The northeast part of the monument in the 2017 model shows decreased volume per 5.11% when compared to the model 1972. Moreover, the calculated distances between the two models from 1972 and 2017 present the greatest values in the case of the southwest and northwest parts of the monument, ranging between −17 cm to 5 cm. Full article