Multiple Registration Research Articles

A novel approach for determining instantaneous centers of rotation of the mandible with an intraoral scanner: A preliminary study.

Recording and reproducing mandibular movements have been of key importance in the practice of dentistry for over a century. Recently, it has become possible to use digital technologies for these tasks. This study presents a preliminary method to try to identify the mandibular instantaneous centres of rotation based solely on intraoral scanners. The dentitions of four participants were scanned, multiple inter-occlusal registrations and buccal scans were performed in closed and opened positions. Blender software was used to align the meshes during the post-scan digital workflow. Bite alignment accuracy was assessed and then improved with a strict exclusion protocol. An automated algorithm was used to find rotations between closed stage and open stage meshes. Our exclusion protocol reduced the bite alignment error significantly (p = 0.001) and the root-mean-square error value of the meshes decreased from 0.09 mm (SD = 0.15) to 0.03 mm (SD = 0.017). However, the remaining translational error caused an unexpectedly large shift in the axis of rotation (mean = 1.35 mm, SD = 0.77) with a 41.83: 1 ratio. As found in other studies, our results showed even a small amount of error during registration can shift the axis of rotation a large amount. This phenomenon will compromise the results of common pantographic methods which assume a rotation axis of the condyle. It also adds valuable information to the concept of instantaneous centers of rotation by revealing their true characteristics.

Spatial Recognition: A Temporal Tale of Multiple Window Spatial Registration.

The performance ability of position logic circuitry of gamma-camera to superimpose the X-Y gains obtained from different pulse height analyzers is multiple window spatial registration (MWSR). This study was conducted to evaluate the feasibility of dual-tracer method using 99mTc and 131I to assess MWSR. The procedure was carried out on a dual-head gamma-camera with rectangular NaI (Tl) crystal using a point source containing 99mTc pertechnetate and 131I-NaI. Pixel coordinates, full width at half-maximum of point spread function at 364 keV and 140 keV, and pixels with maximum count of images for dual detectors were analyzed and compared. The experiment demonstrated an excellent correlation between the X and Y coordinates identified on 364 keV and 140 keV images (Spearman's coefficient of rank correlation: 0.9, P < 0.0001). Intraclass correlation of studies performed on two separate occasions showed a good correlation (k = 0.87) demonstrating the reproducibility of the procedure. Dual-tracer method for evaluation of MWSR is a reproducible, accurate, and logical alternative to the routine National Electrical Manufacturers Association procedure.

Open-source navigation system for tracking dissociated parts with multi-registration.

During reconstructive surgery, knee and hip replacements, and orthognathic surgery, small misalignments in the pose of prosthesis and bones can lead to severe complications. Hence, the translational and angular accuracies are critical. However, traditional image-based surgical navigation lacks orientation data between structures, and imageless systems are unsuitable for cases of deformed anatomy. We introduce an open-source navigation system using a multiple registration approach that can track instruments, implants, and bones to precisely guide the surgeon in emulating a preoperative plan. We derived the analytical error of our method and designed a set of phantom experiments to measure its precision and accuracy. Additionally, we trained two classification models to predict the system reliability from fiducial points and surface matching registration data. Finally, to demonstrate the procedure feasibility, we conducted a complete workflow for a real clinical case of a patient with fibrous dysplasia and anatomical misalignment of the right femur using plastic bones. The system is able to track the dissociated fragments of the clinical case and average alignment errors in the anatomical phantoms of [Formula: see text] mm and [Formula: see text]. While the fiducial-points registration showed satisfactory results given enough points and covered volume, we acknowledge that the surface refinement step is mandatory when attempting surface matching registrations. We believe that our device could bring significant advantages for the personalized treatment of complex surgical cases and that its multi-registration attribute is convenient for intraoperative registration loosening cases.

Privacy-Preserving Authentication Scheme With Revocability for Multi-WSN in Industrial IoT

Wireless sensor network (WSN), as one of the core technology in the Industrial Internet of Things (IIoT) system, plays a critical role in collecting data for the monitoring areas. Security and privacy are essential to ensure the trustworthy completeness of data access and transmission for the WSN-based IIoT system. Recently, a series of excellent privacy-preserving authentication schemes for the WSN-based IIoT system have been proposed. There is, however, strong demand for further improvements in multiple registrations, user revocation, and forward secrecy. Targeted by these security issues, we propose an efficient privacy-preserving authentication scheme with revocability for multi-WSNs in the IIoT environment. In the proposed scheme, the user can access multiple different WSNs with the same identity and password through a single registration. Our scheme is provable secure under the random oracle model, and security analysis via practical circumstances shows that it is able to provide a variety of security requirements, such as user revocation, forward secrecy, etc. In addition, the comparison with related schemes indicates that the proposed one has fewer sensor nodes-based computations and overall communication overheads. It is, therefore, more suitable for the resource-constrained IIoT environment than existing approaches.

A Fraud Prevention and Secure Cognitive SIM Card Registration Model

Background: Most subscriber identification module (SIM) which usually finds their way to mobile phone users are primarily unregistered or pre-registered. Criminals buy these SIM cards, which have fake personal information, activate them and then use them as a channel of attacking vulnerable mobile phone users. Objective: to investigate the existing standards of the registration process, the weakness and how fraudsters leverage the shortcomings of the existing registration to attack unsuspecting subscribers. Methods: The study also proposed an automated theoretical model as an augmented model to ensure the SIM registration process and implementation become secure. Results: In our investigation, we identified that there had been a rise in fraudulent activities in Ghana, and the criminals have adapted to the new trend of committing a crime using mobile phones. The research presented a proposed conceptual model and algorithm for the new SIM registration. The study further conducted a comparative analysis of the principal component adopted to measure the robustness of the registration platform. The criminals mostly use social engineering tactics to trick their victims into disclosing sensitive information or sending money for services yet to be rendered. MNOs request an ID card before registering and activating SIMs, yet criminals can outwit the registration processes and get SIM cards registered through unapproved channels. Conclusion: We found out that the robustness of our model shall prevent SIM pre-registration and unapproved SIM activation due to verification mechanisms in the proposed model. A cognitive learningsystem has automated the registration process that can identify multiple registrations and prevent unapproved activation. Keywords: SIM Fraud; SIM card; Cognitive System; Mobile Network Operators; Intelligent decisionmaking; SIM Registration

Practical semiautomatic global registration of multiple point clouds based on semidefinite programming

Multiple point clouds registration is a prerequisite step for geometry object observation from multiple viewpoints. Most algorithms depend on pose graph or relative poses, and they make the results ambiguous and inconsistent with the original point clouds. However, the existing algorithms based on original data can almost exclusively be applied to simulated data. In this paper, a practical semiautomatic global registration algorithm is proposed. A objective function is proposed; it utilizes correspondences between point cloud pairs directly to describe this problem, making the algorithm easy to interface with other point cloud matching algorithms. Moreover, it can be effectively approximated by semidefinite programming. Since no automatic algorithm can guarantee the correctness of the correspondences, a manual strategy is proposed to filter the correspondences and find the correlation between point clouds. Based on the correlation, irrelevant point clouds can be removed easily in the point cloud set or divide the set into multiple independent parts. Besides, a postprocessing strategy based on the correlation is proposed for refining the results. The qualitative and quantitative experimental results demonstrate that the approach achieves more accurate and robust performance than previous algorithms.

Multi-atlas segmentation and quantification of muscle, bone and subcutaneous adipose tissue in the lower leg using peripheral quantitative computed tomography.

Accurate and reproducible tissue identification is essential for understanding structural and functional changes that may occur naturally with aging, or because of a chronic disease, or in response to intervention therapies. Peripheral quantitative computed tomography (pQCT) is regularly employed for body composition studies, especially for the structural and material properties of the bone. Furthermore, pQCT acquisition requires low radiation dose and the scanner is compact and portable. However, pQCT scans have limited spatial resolution and moderate SNR. pQCT image quality is frequently degraded by involuntary subject movement during image acquisition. These limitations may often compromise the accuracy of tissue quantification, and emphasize the need for automated and robust quantification methods. We propose a tissue identification and quantification methodology that addresses image quality limitations and artifacts, with increased interest in subject movement. We introduce a multi-atlas image segmentation (MAIS) framework for semantic segmentation of hard and soft tissues in pQCT scans at multiple levels of the lower leg. We describe the stages of statistical atlas generation, deformable registration and multi-tissue classifier fusion. We evaluated the performance of our methodology using multiple deformable registration approaches against reference tissue masks. We also evaluated the performance of conventional model-based segmentation against the same reference data to facilitate comparisons. We studied the effect of subject movement on tissue segmentation quality. We also applied the top performing method to a larger out-of-sample dataset and report the quantification results. The results show that multi-atlas image segmentation with diffeomorphic deformation and probabilistic label fusion produces very good quality over all tissues, even for scans with significant quality degradation. The application of our technique to the larger dataset reveals trends of age-related body composition changes that are consistent with the literature. Because of its robustness to subject motion artifacts, our MAIS methodology enables analysis of larger number of scans than conventional state-of-the-art methods. Automated analysis of both soft and hard tissues in pQCT is another contribution of this work.

Minimax Registration for Point Cloud Alignment

The alignment, or rigid registration, of three-dimensional (3D) point clouds plays an important role in many applications, such as robotics and computer vision. Recently, with the improvement in high precision and automated 3D scanners, the registration algorithm has become critical in a manufacturing setting for tolerance analysis, quality inspection, or reverse engineering purposes. Most of the currently developed registration algorithms focus on aligning the point clouds by minimizing the average squared deviations. However, in manufacturing practices, especially those involving the assembly of multiple parts, an envelope principle is widely used, which is based on minimax criteria. Our present work models the registration as a minimization problem of the maximum deviation between two point clouds, which can be recast as a second-order cone program. Variants for both pairwise and multiple point clouds registrations are discussed. We compared the performance of the proposed algorithm with other well-known registration algorithms, such as iterative closest point and partial Procrustes registration, on a variety of simulation studies and scanned data. Case studies in both additive manufacturing and reverse engineering applications are presented to demonstrate the usage of the proposed method.

Prisma-P and Prospero

Systematic review and meta-analysis (SRMA) are the supreme collective scientific evidence available in our literature. Conducting a SRMA is a time consuming, relatively expensive team work. There are many funding options for a relevant SRMA. Hence it is advisable to check whether our proposed SRMA is unique or whether someone else is currently doing it. One can do it by searching PROSPERO maintained by University of York, Cochrane library, PubMed and Google Scholar. It is mandatory to register SRMA; PROSPERO is a major registration option. PROSPERO doesn’t allow multiple registrations of the same topic unless a valid justification can be given. PROSPERO requires a registration which is free of coast. Registration can be done by visiting https:// www.crd.york.ac.uk/prospero/ . After login, we can either register our SRMA or we can search ongoing SRMA. Having a protocol as per PRISMA-P guidelines is mandatory for a smooth registration process. Registration increases the credibility of the SRMA and eliminates the chance of unnecessary duplication of the work. Protocol helps to plan and anticipate problems associated with SRMA. There are different methods for preparing the protocol; Cochrane protocols and PRISMA-P protocols. This editorial will deal with PRISMA-P protocols. Preferred Reporting Items for Systematic review and Meta-Analysis (PRISMA) was published in 2015 ( Moher D, Shamseer L, Clarke M, Ghersi D, Liberati A, Petticrew M, Shekelle P, Stewart LA. Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P) 2015 statement. Syst Rev. 2015;4(1):1. doi: 10.1186/2046-4053-4-1). PRISMA-P specifically talks about protocols, PRISMA about manuscript writing and PRISMA-S about reporting search strategies. PRISMA-P statement (http://www.prisma-statement. org/Extensions/Protocols ) contains some very important items. Administrative information includes identification (Title, original or updated SRMA), registration details, author information (primary and contributors), amendments (indicate ONLY if the protocol is a modification of the earlier one) and support (information regarding funding). Introduction includes rationale and objectives. Methods include eligibility criteria (study characters like PICO, study design and setting, time frame etc.), information sources (all intended digital and other sources), search strategy (MESH terms, Boolean operators, synonyms etc.), study records (data management methods like Rayyan, selection process like who screens the data and data collection process like MS excel / spread sheet), data (define al variables), role of bias in individual studies (describe methods for assessing risk of bias at study level or outcome level or both), data synthesis (describe the statistical aspects), meta bias (publication bias among studies, possibility of selective reporting) and confidence in cumulative evidence.

898P The safety and efficacy of surufatinib for the treatment of advanced neuroendocrine tumors: A prospective, multicenter, real-world study

Surufatinib (a small-molecule inhibitor of VEGFR1-3, FGFR1, and CSF-1R) has exhibited encouraging antitumor activity for the treatment of advanced neuroendocrine tumors (including NEN and NEC) in multiple registration studies. Here, we report the preliminary results of advanced neuroendocrine tumors of an ongoing, multicenter, real-world study of surufatinib + MDT (ChiCTR2100049999). Challenges in tumor clinical trials management in the face of the COVID-19 resurgence period in Shanghai. In this multicenter, single-arm real-world study, adults (18-80) with advanced neuroendocrine tumors (including NEN and NEC) were eligible and received surufatinib (300mg orally, QD) with MDT（multidisciplinary collaborative diagnosis and treatment). The primary endpoint was progression-free survival (PFS) per RECIST 1.1. We minimized the interruptions caused by the pandemic using telemedicine platforms for all patients. This included online consultations, follow-up drug distributions, and health management services. Twenty-three pts were enrolled, with 20 NEN and 3 NEC. At the data cutoff date (April 10, 2022), 15 pts had at least one post-baseline tumor assessment; of them, the confirmed ORR (95%CI) was 20% (4.3-48.1), and DCR (95%CI) was 93.33% (68.1-99.8). Median PFS (mPFS) (95%CI): 10.640 mo (3.796-17.484); median OS: not reached and median duration of follow up was 6.870 mo (6.797-6.943). A pNET patient (NO. 010007) was interrupted by asymptomatic COVID-19 infection 9 mo after enrollment. There are no interruptions caused by COVID-19 for other patients. An NEC patient treated with single agent had a 5.85 mo PFS, evaluated as NE, in whom target lesion resected after baseline. In overall pts (n=23), most commonly (≥3 pts) with hemorrhage, anemia, hypertension, proteinuria, and abdominal pain. Three pts had TRAEs that led to treatment discontinuation. Surufatinib + MDT exhibited promising efficacy and manageable toxicity in pts with advanced neuroendocrine tumors. Now and in the future, it is necessary to design regulatory changes in telehealth adoption for clinical trial design in the pandemic era.

Risk factors for recurrence and complications in acute uncomplicated diverticulitis: A retrospective cohort study

IntroductionAntibiotics for acute uncomplicated diverticulitis (AUD) have been questioned in several studies. Thus, it is of value to identify risk factors for recurrence and complications to identify the best strategy for treatment. The aim was to investigate risk factors for recurrence and complications within at least 1 year after hospitalization for AUD. MethodsThis is a retrospective study, including patients hospitalized with AUD at Helsingborg Hospital and Skåne University Hospital in Sweden during January 1st, 2015–December 31st, 2017. The cohort was primarily collected via the in-patient registry. Patients with multiple registrations, acute complicated diverticulitis, ongoing antibiotics, other diagnoses, immunosuppression and non-CT-verified diagnosis were excluded. Follow-up was ≥1 year. SPSS was used for statistical analysis. ResultsOut of 596 patients, 23% experienced recurrences and 3% experienced complications. Previous diverticulitis [OR 2.86 (CI 1.85–4.55) P < 0.001] and complications [OR 1.35 (CI 1.18–1.42) P < 0.001] were independent risk factors for recurrence. A higher Charlson morbidity index (CMI) [OR 1.27 (1.0–1.61) P = 0.04] and previous diverticulitis [OR 3.68 (1.24–10.9) P = 0.013] were associated with complications. 75% of the patients received antibiotics but this did not significantly improve outcomes. ConclusionA history of previous diverticulitis or complications increases the risk for AUD recurrence. A higher CMI and a history of previous diverticulitis may be risk factors for complications but needs to be further assessed. Treatment with antibiotics does not appear to improve the outcome. Choice of treatment should therefore be individualized and based on risk factors for complications and recurrence.

Эпидемиология наследственных болезней органа зрения в популяциях Российской Федерации

Aim: genetic epidemiological study of hereditary eye diseases in various populations of the Russian Federation and comparative analysis of these findings. Patients and Methods: the sample included 12 ethnic groups from 14 regions of European Russia. The entire population irrespective of gender or age was examined. To confirm a certain type of inheritance of diseases from heterogeneous groups, the material was subjected to the multicomponent analysis used in multiple family registration. The rate of segregation was evaluated using the Weinberg proband method. Molecular genetic tests (Sanger sequencing, MLPA, AFLP, RFLP, whole exome sequencing) were applied. To identify the cases of hereditary disease accumulation in individual populations and/or ethnic groups, the prevalence of certain diseases in this population was calculated using F-distribution to compare the samples of rare diseases. Results: more than 46,000 patients and their relatives with presumably hereditary conditions were examined and data were collected. 554 clinically diverse hereditary diseases in 9,979 individuals were identified. Isolated hereditary eye disease (60 clinical variants) was identifie in 1,407 patients (14.56%). The mean prevalence of isolated hereditary eye disease was 1:2,272 (or 44.01 per 100,000). When assessing patterns of nosological spectrum and prevalence of isolated hereditary eye disease in each population/ethnic group using principal component analysis, 2 clusters were isolated. The first cluster includes 6 Russian populations and the second cluster includes 5 ethnic Volga Region groups, which are more similar to Russian populations than the North Caucasus people. In general, 57 hereditary syndromes (affecting anterior and posterior eye segments) in 1,051 patients were discovered. The mean prevalence of syndromic hereditary eye disease was 1:3,040 (or 32.89 per 100,000). Keywords: ophthalmogenetics, genetic epidemiological study, spectrum, ethnic group, type of inheritance, segregation, accumulation, isolated and syndromic hereditary eye diseases, prevalence, retinal degeneration. For citation: Kadyshev V.V., Ginter E.K., Kutsev S.I. et al. Epidemiology of hereditary eye disease in the populations of Russian Federation. Russian Journal of Clinical Ophthalmology. 2022;22(2):69–79 (in Russ.). DOI: 10.32364/2311-7729-2022-22-2-69-79.

GNSS Independent Position Fixing using Multiple Navigational Features Registration

Safe navigation at sea depends on reliable position information. The easy to use and readily available navigation satellite systems are providing round the clock position information for seafarers, but denial of these services by jamming or spoofing techniques have become frequent, and other means are needed to validate critical navigation information. This paper revisits traditional methods to estimate position and heading of a vessel and offers a framework for computerized calculation of these basic observables without the use of radio-borne external information. Using radar and sea chart information, the paper investigates the quality of navigation information based on observed location of beacons, landmarks, coastlines and buoys. The paper demonstrates convincing accuracy in both position and heading estimation.

Accurate 3-D Shape Measurement for Large Objects Using Speckle-Assisted Fringe Projection and Global Markers Localization

Digital fringe projection (DFP) three-dimensional (3D) shape measurement technique has been extensively researched and applied due to its advantages of high accuracy and high efficiency. To retain the measurement accuracy for large objects, results of multiple measurements are required to be aligned based on the combination of DFP and auxiliary positioning instruments, which decreases the measurement efficiency and limits the practical application. This paper presents an accurate and efficient scheme for large-scale 3D shape measurement based on speckle-assisted fringe projection and global markers localization. Taking advantage of the triple-view geometric constraints and stereo structured-light model, arbitrary 3D surface can be reconstructed with high quality by projecting only four patterns. To align multiple local shape data of large objects without using auxiliary positioning instruments, an accurate data registration method based on global markers reconstruction and localization is presented, which firstly calculates 3D coordinates of all non-coded markers pasted on the object surface by sequential matching, incremental markers reconstruction and global optimization based on bundle adjustment followed by multiple local data registration through local-to-global ICP matching. The experimental results indicate that the proposed method can substantially decrease the accumulated measurement error and achieve commensurate accuracy with the auxiliary positioning methods.

DDMIA: Distributed Dynamic Mutual Identity Authentication for Referrals in Blockchain-Based Health Care Networks

Patients go to multiple healthcare providers for treatment, and their health data is generally distributed among providers. The distributed health data and the decentralized health care system structure make it ideal for blockchain-based health information systems. The authors consider the referral use case; for instance, a patient goes to his primary health Centre (PHC) for treatment and is referred to a hospital. Authentication is usually done using certificates or key cryptography, which could become cumbersome when multiple parties are involved in a healthcare interaction. The security requirements were defined, and a novel multi-party, mutual patient identity authentication scheme called &#x201C;Distributed Dynamic Mutual Identity Authentication (DDMIA)&#x201D; was proposed for the referral use case in a blockchain-based e-health network. The DDMIA enables the PHC to authenticate the patient to the referred hospital. The DDMIA scheme was designed using Elliptic Curve Cryptography. It was proven to be secure by assuming the hardness of the elliptic curve discrete log problem (ECDLP) and Elliptic curve computational Diffie&#x2013;Hellman problem (ECDH) using CK-Model. The formal security analysis using BAN logic proved that the sessions are secure after authentication. The DDMIA scheme was simulated in the AVISPA tool and proven safe against all active attacks. DDMIA scheme was simulated in the AVISPA tool and proven safe against all active attacks. The scheme allows a patient to be authenticated by multiple parties without registering with all parties. It eliminates the need for multiple registration centers as well as digital certificates. Hence, the DDMIA scheme can be implemented for similar multiparty authentication requirements in blockchain-based networks.

Automatic reduction planning of pelvic fracture based on symmetry

ABSTRACT Pelvic fracture is known to be one of the most difficult injuries. The first and foremost step for pelvic fracture reduction is structural recovery. However, due to lack of data on healthy pelvis before fracture, the result of fracture reduction is entirely based on the experience of surgeons. This study proposed a novel method for automatic reduction planning based on the symmetry of the pelvis (pelvic symmetry reduction, PSR), which could provide a template for the pelvic reduction surgery as well as related surgical robot. A symmetrical area (ROI) without fracture fragments was extracted from the fractured pelvis through multiple SP mirroring, ICP registration and Boolean operation, so as to acquire the target position for reduction. Fifteen healthy pelvic models and three fractured pelvises were acquired to evaluate the accuracy and validity of the PSR method separately. The mean error of anatomical landmarks is 2.94 mm (translational error) and 1.08°, 0.67°, and 1.96° (rotational error on X, Y and Z axes, respectively). The average global distance error is below 4 mm except for a model with poor symmetry. The results of the actual fractured pelvis were recognised by clinicians. These results demonstrate the feasibility of the PSR method for restoring anatomical structure of the pelvis and achieve higher reduction accuracy than previous approach.

Curating a longitudinal research resource using linked primary care EHR data-a UK Biobank case study.

Primary care EHR data are often of clinical importance to cohort studies however they require careful handling. Challenges include determining the periods during which EHR data were collected. Participants are typically censored when they deregister from a medical practice, however, cohort studies wish to follow participants longitudinally including those that change practice. Using UK Biobank as an exemplar, we developed methodology to infer continuous periods of data collection and maximize follow-up in longitudinal studies. This resulted in longer follow-up for around 40% of participants with multiple registration records (mean increase of 3.8 years from the first study visit). The approach did not sacrifice phenotyping accuracy when comparing agreement between self-reported and EHR data. A diabetes mellitus case study illustrates how the algorithm supports longitudinal study design and provides further validation. We use UK Biobank data, however, the tools provided can be used for other conditions and studies with minimal alteration.

MPCR-Net: Multiple Partial Point Clouds Registration Network Using a Global Template

With advancements in photoelectric technology and computer image processing technology, the visual measurement method based on point clouds is gradually being applied to the 3D measurement of large workpieces. Point cloud registration is a key step in 3D measurement, and its registration accuracy directly affects the accuracy of 3D measurements. In this study, we designed a novel MPCR-Net for multiple partial point cloud registration networks. First, an ideal point cloud was extracted from the CAD model of the workpiece and used as the global template. Next, a deep neural network was used to search for the corresponding point groups between each partial point cloud and the global template point cloud. Then, the rigid body transformation matrix was learned according to these correspondence point groups to realize the registration of each partial point cloud. Finally, the iterative closest point algorithm was used to optimize the registration results to obtain the final point cloud model of the workpiece. We conducted point cloud registration experiments on untrained models and actual workpieces, and by comparing them with existing point cloud registration methods, we verified that the MPCR-Net could improve the accuracy and robustness of the 3D point cloud registration.

Reliability of Trial Information Across Registries for Trials With Multiple Registrations

Clinical trial registries are important for gaining an overview of ongoing research efforts and for deterring and identifying publication bias and selective outcome reporting. The reliability of the information in trial registries is uncertain. To assess the reliability of information across registries for trials with multiple registrations. For this systematic review, 360 protocols of randomized clinical trials (RCTs) approved by research ethics committees in Switzerland, the UK, Canada, and Germany in 2012 were evaluated. Clinical trial registries were searched from March to September 2019 for corresponding registrations of these RCTs. For RCTS that were recorded in more than 1 clinical trial registry, key trial characteristics that should be identical among all trial registries (ie, sponsor, funding source, primary outcome, target sample size, trial status, date of first patient enrollment, results available, and main publication indexed) were extracted in duplicate. Agreement between the different trial registries for these key characteristics was analyzed descriptively. Data analyses were conducted from May 1 to November 30, 2020. Representatives from clinical trial registries were interviewed to discuss the study findings between February 1 and March 31, 2021. The analysis included 197 RCTs registered in more than 1 trial registry (151 in 2 registries and 46 in 3 registries), with 188 trials in ClinicalTrials.gov, 185 in the European Union Drug Regulating Authorities Clinical Trials Database (EudraCT), 20 in ISRCTN, and 47 in other registries. The agreement of key information across all registries was as follows: 178 of 197 RCTs (90%; 95% CI, 85%-94%) for sponsor, 18 of 20 (90%; 95% CI, 68%-99%) for funding source (funding was not reported on ClinicalTrials.gov), 154 of 197 (78%; 95% CI, 72%-84%) for primary outcome, 90 of 197 (46%; 95% CI, 39%-53%) for trial status, 122 of 194 (63%; 95% CI, 56%-70%) for target sample size, and 43 of 57 (75%; 95% CI, 62%-86%) for the date of first patient enrollment when the comparison time was increased to 30 days (date of first patient enrollment was not reported on EudraCT). For results availability in trial registries, agreement was 122 of 197 RCTs (62%; 95% CI, 55%-69%) for summary data reported in the registry and 91 of 197 (46%; 95% CI, 39%-53%) for whether a published article with the main results was indexed. Different legal requirements were stated as the main reason for inconsistencies by representatives of clinical trial registries. In this systematic review, for a substantial proportion of registered RCTs, information about key trial characteristics was inconsistent across trial registries, raising concerns about the reliability of the information provided in these registries. Further harmonization across clinical trial registries may be necessary to increase their usefulness.

A novel digital technique for maintaining maxillomandibular relations in fixed prosthetic rehabilitations

Introduction: In fixed prosthetic rehabilitations, the restorations must be designed and fabricated in a proper maxillomandibular relationship, with correct vertical dimensions of occlusion (VDO) and centric relation (CR). This short communication introduces a novel digital technique that allows to obtain the maxillomandibular record and transfer it throughout the treatment procedure. Methods: The protocol consisted of the following steps: 1. scan-jig planning and production; 2. maxillomandibular record prior to tooth preparation; 3. sequential tooth preparation and post-operative data recording through a cut-out and re-scan protocol; 4. control of the pre- and post-operative alignment of the scans in the correct VDO and CR, design and delivery of the definitive restorations. Results: There was no clinical difference in the spatial positions of the virtual models and the relationships between the arches throughout every step of the treatment. Conclusion: The main advantages of this technique are that it allows to maintain the therapeutic maxillomandibular relationship after its clinical evaluation, to reduce chair time and to avoid inaccuracies determined by multiple bite registrations.