Three-dimensional Digital Models Research Articles

A Scaled Monocular 3D Reconstruction Based on Structure from Motion and Multi-View Stereo

Three-dimensional digital modeling at actual scales is essential for digitally preserving cultural relics. While 3D reconstruction using a monocular camera offers a cost-effective solution, the lack of scale information in the resulting models limits their suitability for geometric measurements. Objects with monotonous textures, such as batteries, pose additional challenges due to insufficient feature points, increasing positional uncertainty. This article proposes a method incorporating point and line features to address the scale ambiguity in multi-view 3D reconstruction using monocular cameras. By pre-measuring the lengths of multiple sets of real line segments, building a lookup table, and associating the line features in different images, the table was input into the improved reconstruction algorithm to further optimize the scale information. Experimental results on real datasets showed that the proposed method outperformed the COLMAP method by 70.82% in reconstruction accuracy, with a scale recovery reaching millimeter-level accuracy. This method is highly generalizable, cost-effective, and supports lightweight computation, making it suitable for real-time operation on a CPU.

Forearm range of motion in Allosaurus fragilis (Dinosauria: Theropoda)

ABSTRACT Forelimb bones of the Early Jurassic theropod Allosaurus fragilis were digitally manipulated based on three-dimensional (3D) digital models. Bony articular surface margins were used as limits to determine the range of motion (ROM) for each forelimb joint, and to test functional hypotheses of forelimb usage. We discuss the effects of palaeopathology at the right shoulder joint on inferring ROM in the forelimb of Allosaurus. It is considered that the glenoid aberration of this sub-adult specimen occurred in early ontogeny and lasted for a long period of time, affecting to varying degrees the development of the whole right arm (but not the manus). The relatively large ranges of extension and flexion of manual joints indicate well grasping ability consistent with early-diverging theropods. The limited ROM of the shoulder joints of Allosaurus suggests that the forelimbs were predominantly prey-acquiring but could go no further forward, indicating that the first contact with prey was made by the mouth. The manus could assist in grasping prey on the chest or below the neck or hooking objects.

Trifecta Outcomes After Use of 3-Dimensional Digital Models for Planning of Robotic Prostatectomy

Planning complex operations such as robotic-assisted laparoscopic radical prostatectomy (RALP) requires surgeons to review 2-dimensional magnetic resonance imaging (MRI) scans to understand 3-dimensional (3D) patient anatomy. Three-dimensional digital models for planning RALP may allow better understanding of patient anatomy and may lead to better patient outcomes, although data are currently limited. To determine surgical outcomes after RALP when surgeons reviewed 3D digital models during operative planning. This study was a planned secondary analysis of a multicenter, single-blind, randomized clinical trial conducted at 6 large teaching hospitals in the US. The study was conducted between January 1, 2019, and December 31, 2022, and included patients undergoing RALP. Patients were assessed and recruited at the time of surgical consultation. Final data analysis was conducted between August and December 2023. Patients were randomized to either a control group undergoing usual preoperative planning with prostate biopsy results and multiparametric MRI only or to an intervention group in which imaging and biopsy results were supplemented with a 3D digital model. This model was viewed on the surgeon's mobile phone in 3D format and picture-in-picture on the robotic console screen. The primary outcome measure for the overall study was oncologic outcomes after RALP, measured as prostate-specific antigen (PSA) detectability. Secondary outcomes were sexual function and urinary function, measured with Sexual Health Inventory for Men (SHIM) scores and rates of urinary incontinence, respectively, as well as use of salvage or adjuvant radiation therapy (RT) or androgen deprivation therapy (ADT). Trifecta outcomes were defined as undetectable PSA without RT or ADT, SHIM score categorically the same or greater than preoperatively, and complete continence. Univariate analysis was performed to compare outcomes between groups. This trial included 92 patients undergoing RALP (51 in the control group and 41 in the intervention group). Their mean (SD) age was 62 (7.4) years; 10 patients (10.9%) were Black and 67 (72.8%) were White. At 18 months postsurgery, the intervention group had lower rates of biochemical recurrence (PSA level >0.1 ng/mL, 0 vs 7 [17.9%]; absolute difference, 17.9% [95% CI, 1.8% to 31.8%]; P = .01) and were significantly less likely to undergo adjuvant or salvage RT (1 [3.1%] vs 12 [31.6%]; absolute difference, 28.5% [95% CI, 10.1% to 46.7%]; P = .002) compared with the control group. Sexual function at 18 months postsurgery was significantly better in the intervention group (mean [SD] SHIM score, 16.8 [8.7] vs 9.8 [7.7]; absolute difference, 7.0 [95% CI, 2.6 to 11.4]; P = .002) and urinary function was unchanged (total continence, 22 [78.6%] vs 29 [80.6%]; absolute difference, 2.0% [95% CI, -17.9% to 21.9%]; P = .84) compared with the control group. Trifecta outcomes were achieved for 12 (48.0%) patients in the intervention group and 3 patients (10.0%) in the control group (absolute difference, 38.0% [95% CI, 14.4% to 61.6%]; P = .002). In this secondary analysis of a randomized clinical trial, patients whose surgical planning of RALP involved 3D digital models had better oncologic and functional outcomes. Further work should assess the effect of 3D models in a broader set of patients, physicians, and hospital settings. ClinicalTrials.gov Identifier: NCT03943368.

Development and testing of hybrid (PNM–CFD) mathematical model and numerical algorithm for description of fluid flows in three-dimensional digital core models

Numerical simulation of fluid flow in porous and fractured rocks is an important task for many industrial applications. The most common approaches to constructing such models are direct (CFD or lattice Boltzmann) and porous network (PNM) modeling. Each approach has its own advantages and disadvantages. This paper presents a hybrid mathematical PNM–CFD model for describing fluid flows in three-dimensional digital core models, which has the high speed performance of PNM approaches and high accuracy of CFD models. Numerical technique has been developed for describing fluid flows in three-dimensional digital core models using a hybrid PNM–CFD model. The numerical technique links a one-dimensional pore network solver and a three-dimensional CFD solver into a combined model in original way by constructing a single pressure field for the entire computation domain. To validate the model, several tests were performed, including flow in straight channels and numerical simulation of fluid flow in a microfluidic chip. The test results have shown the adequacy of the hybrid model performance. The hybrid model for determining pressure drop in a branched network with three-dimensional chambers has an error of no more than 5 % when compared to experimental data. Similarly, the error in calculating velocity does not exceed 7 % when compared to the full three-dimensional calculation. The hybrid model has shown an almost twofold increase in calculation speed compared to the full three-dimensional model.

A Comparison of Tooth Size and Arch Dimensions Among Measurements Taken Intraorally with 3D-Printed and Digital Models Obtained from Intraoral Scans.

To compare measurements of tooth size and arch dimensions among those taken directly intraorally with those made on digital and 3D printed models produced by intraoral scanning. Sixty-six participants were recruited. Intraoral tooth size and arch measurements were taken intraorally with a digital caliper. Digital impressions were taken with an iTero® intraoral scanner. The three-dimensional digital models were measured using a 3D diagnostics tool (OrthoCAD software). The same digital models were used to fabricate physical models using a resin 3D printer (Elegoo Saturn). The measurements were repeated on 3D printed models by using the digital caliper. The recorded parameters included mesiodistal tooth widths, transverse, and antero-posterior dimensions. All measurements were repeated to assess intra- and inter- examiner reliability. The validity of each measurement method was assessed by repeated measures ANOVA with post-hoc pairwise comparisons (p<0.5). The mean differences among three methods for all parameters were statistically significant (p<.05) but were considered to be clinically insignificant, except for the upper intercanine width. Direct intraoral measurements tend to be smaller than the digital and 3D printed models. The ICCs values indicated excellent intra- and inter-examiner reliability which demonstrates high reproducibility for all measurements on all model types. Direct intraoral measurements tend to be smaller than the digital and 3D printed models. However, the accuracy of measurements made directly intraorally, and on digital and 3D models from intraoral scans is clinically acceptable, except for the upper intercanine width. Key words:Tooth measurements, Accuracy, Dental models, 3D printing, Digital model.

Prediction of formation abrasiveness under the action of a PDC bit based on the fractal dimension of a rock surface

During rock drilling, a drill bit will wear as it breaks the rock. However, there is no uniform grading standard for rock abrasiveness. To solve this problem, the wear mechanisms of a polycrystalline diamond compact (PDC) bit and the formation it is drilling into are analyzed in depth, and an abrasiveness evaluation method based on the fractal dimension of the rock surface topography is established. Initially, a three-dimensional digital model is generated from a scanning electron microscope image of the rock after drilling; next, an evaluation of the irregularities on the rock surface is performed using an adapted Weierstrass–Mandelbrot (W-M) function to ascertain the fractal dimensionality. Then, the microcontact characteristics of the contact surface between the formation and the PDC bit are analyzed, and the distribution of the microconvex contact points of the two-body friction pair in a region is obtained. Because the sliding friction between the drill bit and the rock produces a large amount of heat, according to the contact area formula of the friction surface and heat conduction theory, the temperature rise and overall temperature distribution of the formation and PDC bit under the condition of sliding friction are revealed, and the real contact area between the formation and the drill bit within a certain temperature range is obtained. Finally, the evaluation index of rock abrasiveness under sliding conditions is established by adopting the wear weight loss of the rock cutting tool per unit volume as the index of rock abrasiveness, and the model is verified by a microdrilling experiment. The research in this paper is highly important for improving the rock-breaking efficiency and bit service life during drilling.

Intangible cultural heritage based on finite element analysis: force analysis of Chinese traditional garden rockery construction

In traditional Chinese rockery stacking, the peculiarity of the materials and reliance on the personal experience of artisans during the construction process make it challenging to scientifically quantify the structural stress and use scientific methods to ensure the stability of rockery structures and the safety of the construction process. Therefore, the intangible cultural heritage of rockery stacking technology faces the problem of scientific structural inspection and risk estimation during the construction process. This study uses a finite element analysis to evaluate the structural stress of the rockery-stacking site to contribute to the sustainable development and protection of this intangible cultural heritage. After establishing a three-dimensional digital model, mechanical calculations are carried out for the overall structure of the rockery and its different parts. The analysis identifies three types of structural factors in artificial rockeries: contact, structure, and load. It also effectively and intuitively identifies the weak points in the rockery structures and provides an assessment of risks, offering valuable insights for risk prevention and for the construction and maintenance of the structures. These results contribute to the structural safety inspection of traditional Chinese rockery stacking and the structural evaluation of existing rockery heritage.

Finite element analysis of a novel anatomical plate in posterolateral plateau fractures.

This study aims to analyze the biomechanical characteristics of posterolateral plateau fractures fixed by a novel anatomical plate using finite element analysis. A three-dimensional digital model of the full length of right tibiofibula was obtained by CT scanning. A posterolateral tibial plateau fracture model was then created. The acquired fracture model was assembled with 4 groups of internal fixations: Group A, novel anatomical plate; Group B, straight buttress plate; Group C, oblique T-shaped locking plate; Group D, two lag screws. Axial loads of 500, 1,000 and 1,500 N perpendicular to the horizontal plane were used to simulate the stress on the lateral plateau of a 65 kg person standing, walking and fast running. Vertical displacements of the posterolateral fragments in each of the four groups gradually increased under loads from 500 N to 1,500 N. The maximum displacement of the fracture fragment in four groups were all located on the lateral side of the proximal part, and the displacement gradually decreased from the proximal part to the distal end. The maximum displacement values under the axial load of 1,500 N was in the following order: novel anatomical plate (1.2365 mm) < oblique T-shaped locking plate (1.314 mm) < two lag screws (1.3747 mm) < straight buttress plate (1.3932 mm). As the axial load increased, the stress value of the different internal fixation models gradually increased. The stress behavior of the same internal fixation model under different loads was similar. The maximum stress value under the axial load of 1,500 N was in the following order: novel anatomical plate (114.63 MPa) < oblique T-shaped locking plate (277.17 MPa) < two lag screws (236.75 MPa) < straight buttress plate (136.2 MPa). The patients with posterolateral plateau fractures fixed with a novel anatomical plate in standing, walking and fast running can achieve satisfactory biomechanical results, which lays the foundation for future applications. At the same time, clinical fracture types are often diverse and accompanied by damage to the soft tissue. Therefore, the ideal surgical approach and appropriate internal fixation must be selected based on the patient's injury condition.

Формирование цифровой модели угольного месторождения в горно-геологической информационной системе МАЙНФРЭЙМ

Digitalization of enterprise management using Russian software is the main trend in the development of the country's mining sector. Sharp fluctuations in demand and prices in the mineral markets, as well as the development of technical tools for mechanization and automation of technological processes along with a systematic increase in their cost affect the financial performance of mining companies. This determines the need for a rapid adoption of technical, technological and organizational decisions, which, along with the requirements of the company's owners and regulators to obtain prompt, reliable and the most complete information about the production process explains the urgent need for the prompt introduction of digital control systems for mining operations. In the article the authors describe an algorithm to design a digital model of the mining and geological system, including a digital geological model of the deposit, digital models of mine workings and the surface topography, based on the experience of creating three-dimensional digital models of complex-structured coal deposits. The basic software suite for designing a digital management system for mining operations is the MINEFRAME mining and geological information system developed at the Mining Institute of the Kola Scientific Center of the Russian Academy of Sciences. MINEFRAME allows to perform a full range of tasks aimed at creation of a digital 3D model of the mining and geological system for a coal deposit with the possibility to account for the complex bedding in the modelling. High accuracy and correctness of the input geological sampling data is achieved by means of tools to check for errors in the tables of borehole collar coordinates, inclinometry and sampling. The wireframe modelling methods implemented in MINEFRAME provide the possibility to create wireframe models of seams with high detail in the fracture zones.

Seeing is believing – The application of Three-Dimensional modelling technologies to reconstruct the final hours in the life of an ancient Egyptian Crocodile

The application of non-invasive radiography (X-ray and CT) to an ancient Egyptian crocodile mummy demonstrated a high level of corporeal preservation achieved through artificial embalming. Analysis revealed numerous anomalies within the abdomen of the crocodile which merited further investigation using digital three-dimensional modelling technologies. Improving the clarity of the CT scan data enabled the authors to identify the anomalies which included a metal fish hook and a small fish. Segmentation of the CT scan data enabled the virtual extraction of the hook from within the confines of the mummy and its replication, firstly in plastic and then in its original material, bronze.Through the scientific analysis of the mummy, the authors reconstruct the biological biography and life history attributes of the animal, and consider the human-animal relationships and religious beliefs behind its post-mortem preservation. The study explores the application of the 3D technologies applied to archaeological materials and the novel implementation of experimental techniques to reproduce the anomaly. The investigation provided the ability to enhance the study, interpretation and display of the mummy; a matter of particular relevance in the case of mummified remains where anomalies are not directly visible. The authors consider the improved accessibility to cultural artefacts made possible through the application of enhanced visualisation techniques in the heritage sector.

A Construction Method for Three-Dimensional Digital Model of Substation Equipments Integrating Grid Information Model

Abstract Building a three-dimensional digital model of a substation is a key technology for achieving intelligent operation and maintenance of substations. However, the widely used GIM technology currently has obvious shortcomings in spatial attribute correlation, and cannot meet the application requirements. This paper proposes a three-dimensional digital model modeling method for substation equipments, which improves the general standardization transplantation and spatial attribute association ability based on GIM. This method integrates the GIM data standard, establishes a mapping relationship between GIM model data and JSON instances, fully preserves the attribute information of the model, and can easily obtain a three-dimensional slice model of substation equipments. The feasibility of the proposed method was verified through experiments.

Multi-factor numerical simulation and response characteristics of two-dimensional nuclear magnetic resonance in digital cores

Two-dimensional nuclear magnetic resonance (2D NMR) logging is an important technology for reservoir evaluation in oil and gas exploration and development, and it has unique advantages in fluid identification. However, in oil shale reservoirs, the mechanisms of 2D NMR logging are complex, and the response characteristics of various factors are unclear. Numerical simulation based on digital core is a significant method to study the influences of multiple factors on 2D NMR. This manuscript introduces the construction method of high-resolution three-dimensional (3D) digital core models, and expounds the principle and workflow of 2D NMR numerical simulation. High-resolution 3D digital cores were constructed based on X-CT, MAPS, and QEMSCAN data of Berea sandstone and Daqing Gulong shale, respectively. Based on 3D digital cores, 2D NMR numerical simulations were carried out on temperature/viscosity, echo spacing, and frequency. Then, 2D NMR mechanisms were analyzed and the response characteristics of multiple factors were summarized. The results show that the T2 and T1 of the water peak have a linear negative correlation with temperature/viscosity, and the T2 and T1 of the oil peak have a linear positive correlation. For Daqing Gulong shale, the T2 of the water peak has a linear positive correlation with echo spacing, while for Berea sandstone, echo spacing has little effect. For Berea sandstone, the T1 of the water peak is linearly positively correlated with frequency. For Daqing Gulong shale, the T1 of the water peak and oil peak are both linearly positively correlated with frequency. The response characteristics of multiple factors could provide a reference and basis for the interpretation and evaluation of 2D NMR logging under complex conditions.

Zygoma Asymmetry in Non-Syndromic Patients with Unilateral Cleft Lip and Palate

Background: Cleft lip and palate are often accompanied by maxillary asymmetry and midface hypoplasia. However, there has been limited examination of the symmetry of the zygoma in these patients. In this study, computed tomography scans prior to alveolar bone grafting are utilized to examine zygomatic symmetry through width, projection, and volume. Methods: Retrospective review was conducted of patients with nonsyndromic unilateral cleft lip and palate with eligible scans prior to alveolar bone grafting at our institution. Anterior zygomatic width, posterior zygomatic width, and zygomatic projection were measured on axial images oriented to the Frankfort horizontal, and three-dimensional digital models of each zygoma were created from the computed tomography data to estimate zygoma volume. These measurements were then compared on cleft and noncleft sides. Results: Twenty-two patients were included in this study. The mean (95% CI) zygoma volume of the cleft side and non-cleft side was 4219 mm3 (3858-4574 mm3) and 4286 mm3 (3932-4660 mm3), respectively, with a mean difference of −67 mm3 ([−402-266 mm3]; P = .704). The zygomatic projection of the cleft side was 43 mm (41-45 mm) in comparison to 47 cm (45-49 mm) for the non-cleft side. Mean difference in zygomatic projection was −4 mm (−5 to −2 mm, P &lt; .001). Mean anterior zygomatic width was greater on the cleft side (42 mm [41-44 mm]) than the non-cleft side (41 mm [40-42 mm]; P = .037). No significant difference was found between posterior zygomatic width of the cleft side (59 mm [58-60 mm]) and non-cleft side (58 mm [57-59 mm]; P = .118). Conclusions: Upon preoperative image analysis in patients with non-syndromic, unilateral lip and palate clefts, zygomatic projection was significantly different between cleft and non-cleft sides. Evaluation of zygoma asymmetry should be included as a component of the physical exam when assessing a patient with unilateral cleft lip and palate, as improved awareness of existing zygomatic asymmetry could aid in setting patient expectations, improving satisfaction/outcomes, and in planning for potential surgical correction.

ARCHITECTURAL PHOTOGRAMMETRY APPLIED TO THE CATALOGING OF HISTORICAL HERITAGE. A CASE STUDY OF A BUNKER IN LA LÍNEA DE LA CONCEPCIÓN, SPAIN

&amp;lt;p&amp;gt;Photogrammetry is an emerging tool in architecture, conservation, cataloging, and maintenance of heritage, offering a precise and efficient methodology for generating three-dimensional digital models. This work presents a comparative study of photogrammetric methods, focused on a lowcost software application, with the aim of evaluating its effectiveness in capturing and faithfully representing architectural and cultural elements, such as the bunkers located in La L&amp;amp;iacute;nea de la Concepci&amp;amp;oacute;n (Spain), where the seismic hazard is not neglectable. The results reveal that the method choice depends on the object being digitized. Some programs are more suitable for capturing fine details, while others excel in reconstructing more complex structures.&amp;lt;/p&amp;gt;

A two-dimensional photographic and three-dimensional digital dental model comparative analysis in maxillary anterior teeth

Objective: To assess the accuracy of two-dimensional (2D) photographs in measuring esthetic parameters of the maxillary anterior teeth by comparing them with measurements obtained from three-dimensional (3D) dental models. Methods: A total of one hundred volunteers (49 males, 51 females, aged 18-23 years) were recruited from School and Hospital of Stomatology, Wuhan University from January to February 2024. 3D digital models of their dentitions were obtained using an intraoral scanner, and standardized frontal 2D intraoral photographs were captured with a digital camera. The lengths, widths and width/length ratio of the bilateral incisors, lateral incisors and canines were measured on both the 3D digital models and the 2D intraoral photographs. The width ratios of adjacent maxillary anterior were also calculated on the 2D intraoral photographs and the frontal view of 3D digital models. Results: The widths of lateral incisors [(5.85±0.60) mm] and canines [(4.73±0.71) mm] and the lengths of canines [(8.72±0.96) mm] in the 2D intraoral photographs were significantly lower than those in 3D digital models [(6.65±0.59), (7.76±0.60), (8.90±0.86) mm] (t=-18.24, P<0.001; t=-54.43, P<0.001; t=-4.40, P<0.001), while there were no significant differences in the lengths and widths of the other teeth (P>0.05). The width/length ratios measured from the 2D intraoral photographs for the lateral incisors and canines (0.74±0.08, 0.55±0.08) were significantly lower than those measured in the 3D digital models (0.84±0.09, 0.88±0.09) (t=-19.68, P<0.001; t=-50.21, P<0.001), and the width/length ratio of the central incisors showed no significant difference between the two groups (P>0.05). The width ratios of canines/lateral incisors and lateral incisors/central incisors measured on the 2D intraoral photographs (0.72±0.06, 0.85±0.11) were significantly smaller than those measured in the frontal view of 3D digital models (0.75±0.06, 0.89±0.11) (t=-9.31, P<0.001; t=-6.58, P<0.001). Conclusions: There is a difference between 2D and 3D measurement results of teeth in the esthetic area and the magnitude of the difference varies with their position in the dental arch. When analyzing the measurement of the anterior teeth, it is necessary to choose the appropriate method according to the target tooth position.

Impact of arthroscopy on post-procedure intra-articular elbow injections: A cadaveric study.

To determine the influence of arthroscopy and injection volume on post-procedure intra-articular (IA) injection extravasation. Ex vivo prospective study. A total of 40 paired canine cadaver forelimbs. After radiographs and computed tomography (CT) scans with three-dimensional (3D) digital bone model reconstructions, elbows were randomly assigned to the arthroscopy or control group and randomly assigned to receive an IA injection of 2 or 4 mL of contrast. Elbow arthroscopy was performed on assigned specimens, followed by IA injections of contrast in all elbows, and imaging was repeated. 3D digital model volumes were compared. Images were interpreted and scored for extravasation by a radiologist unaware of treatment and volume assignments. Based on CT images and regardless of treatment group, IA injections of 4 mL resulted in a mean extravasation score of 2.25 (SD 0.97) versus 1.55 (SD 1.05) (p = .02) for 2 mL IA injections. The change in 3D model volumes after IA injections was a mean of 13.2 cm3 (SD 5.85) after 4 mL injections, compared to 6.97 cm3 (SD 6.28) (p = .003) after 2 mL injections. On radiographic evaluation, but not CT, the mean extravasation scores were 2.45 (SD 1.15) for the arthroscopy group and 1.25 (SD 0.79) for the control group (p < .001). A larger volume of IA injection resulted in higher CT extravasation scores and larger 3D volumes regardless of arthroscopic treatment. IA injections performed immediately after arthroscopy resulted in 50% or less extravasation, especially with a smaller IA injection volume.

Effect of bone-marrow-derived mesenchymal stem cells on the rate of orthodontic tooth movements in rabbits.

This study aimed to evaluate the effects of BMAC and BM-MSCs on orthodontic tooth movements in rabbits. A100- gram nickel-titanium closed-coil springs were used to initiate orthodontic tooth movement of the lower first premolars in 35 male New Zealand rabbits for 21 days. Using a split-mouth design, autologous BMAC or BM-MSCs were submucosally injected into the right sides of the lower jaw, while the left sides served as the control. On days 7, 14, and 21, a three-dimensional digital model scan was used to measure the amount of tooth movement. The microfocus computed tomography (Micro-CT) and histological findings were examined on day 0 as the baseline measurement and on days 7, 14, and 21. Compared to the control group, the quadrant receiving BMAC and BM-MSCs had a considerably greater amount of tooth movement. Histomorphometric analysis revealed that both BMAC and BM-MSCs had significantly higher numbers of osteoclasts and active bone-resorptive lacunae. The resorptive changes were greater in the BMAC and BM-MSCs groups than in the control group. The submucosal injection of BMAC and BM-MSCs accelerates orthodontic tooth movement (OTM) by decreasing bone density and supplying more osteoclast progenitor cells.

Validity of digital analysis versus manual analysis on orthodontic casts

As artificial intelligence within digital processes continues to advance and replace conventional manual workflows, it is crucial that digital data are consistent with analog data. The aim was to evaluate the validity and time efficiency of digital cast analysis on digital models in comparison with the manual, gold standard, cast analysis on plaster models. Cast analysis was performed on 30 patients in three various methods: manually measured variables on plaster models (MP), manually measured variables on digital three-dimensional models (MD), and automatically measured variables on digital three-dimensional models (AD) on digital models. Digital cast analysis was performed in CS Model+. Analyses included metrical and categorical variables and the required work time. Measurements in MD and AD were validated to MP. Validity of the metrical variables was analyzed with Bland-Altman, Dahlberg's formula, and paired sample t test. Categorical variables were validated by Cohen's Kappa. Work time was analyzed with Wilcoxon signed-rank test. Metrical variables had measurement errors ranging 0.4 to 1.4 mm between MP-MD, and 0.6 to 3.2 mm between MP-AD. Observations of categorical variables had a moderate to strong (0.65 to 0.9) level of agreement between MP-MD, and a weak to moderate (0.4 to 0.68) level of agreement between MP-AD. Data for dental stage, vertical, and transversal relation was not provided in AD. Cast analysis was performed quicker digitally, P ≤ 0.05. Digital cast analysis is consistent with manual cast analysis for metrical variables. Analyses of categorical variables show a weak level of agreement with automatic digital analysis, such as space conditions and midline assessments. Digital cast analysis optimizes time compared with manual cast analysis, with automatic analysis being the fastest.

Quantitative prediction methods and applications of digital ore deposit models

With the depletion of surface mineral deposits, attention has shifted to deep mineral exploration prospecting. The emergence of three-dimensional digital ore deposit models, facilitated by the advancement of computer technology, has transformed traditional two-dimensional geological models into computer-recognizable numerical-symbolic digital models. This transformation allows qualitative geological concepts, originally expressed in natural language, to be quantitatively expressed, thereby enhancing the accuracy of deep mineral exploration. This paper first outlines the development from traditional ore deposit models to digital ore deposit models, asserting that digital ore deposit models can encompass a more comprehensive array of multidisciplinary geological information, including mineralogy, ore deposit types, structural geology, geochemistry, and geophysics. Building upon digital ore deposit models, a three-dimensional geological model is constructed, combining regional metallogenic regularities, identifying ore-forming favorable information, and conducting quantitative extraction. Subsequently, a comprehensive prospecting model is established, followed by the integration of deep learning methods for deep-seated mineral exploration, forming a unified system of quantitative prospecting methodology for hidden mineral deposits under the framework of geological prospecting models, three-dimensional geological modeling, and three-dimensional quantitative prospecting. Finally, using the Zaozigou gold deposit in Gansu Province as a case study, this approach is applied to mineral exploration prospecting, delineating prospective target areas and providing valuable reference for future exploration efforts.

Palatal Morphology After Treatment of Children With Obstructive Sleep Apnoea Using the Modified Twin-Block Appliance

ObjectiveTo investigate changes in the upper maxillary palates of children with obstructive sleep apnoea (OSA) and mandibular retraction who were treated using modified twin-block appliances (MTBAs). MethodsThirty-five OSA children (age: 6-12 years) with mandibular retraction were included as the experimental group and 35 children who were Angle's class I but without mandibular retraction were included as the control group. The experimental group was treated with MTBA. Plaster models were made before the treatment and at the end of the 6-month treatment period. Plaster models of the control group were made at inclusion and after 6 months. Some plaster models were excluded because of damage or their failure to exhibit sufficiently clear marks, which left 26 pairs each for the experimental and control groups. The gender and age of the experimental group were matched with those of the control group at the end of the treatment. Three-dimensional (3D) digital model information was gathered using the external oral scanning model, and the data were extracted and analysed statistically to clarify the morphologic improvement in the maxillopalatine in OSA children treated using MTBAs. ResultsAfter the OSA children with mandibular retraction were treated with MTBAs, the maxillary intercusp width, intermolar width, anterior palate width, posterior palate width, and surface area and volume of the maxillary palate significantly increased (*P < .05). By contrast, the anterior palatal height–apex level (H3) significantly decreased (*P < .05). ConclusionsCompared with the control group, the narrow maxillary arch and basal bone were significantly enlarged after the OSA children with mandibular retraction were treated using MTBAs. The palatal surface area and volume increased, thereby allowing more space for accommodating the tongue and relieving transverse dissonance of the dentition.