Patient-specific occlusal positioning splints can be regarded as physical realisations of planned mandibular transformations. However, the achieved mandibular pose may differ from the planned one because of acquisition, registration, fabrication, and positioning errors. This study presents a transformation-based biomedical engineering framework for quantifying mandibular positioning accuracy and propagating the resulting error to a simulated temporomandibular joint configuration. Multimodal 3D data, including CBCT, facial motion acquisition, and dental scans, were integrated in a common coordinate system. Positioning splints corresponding to selected mandibular poses were designed and fabricated, and their realised positions were evaluated using repeated scans of plaster models. Discrepancies between planned and achieved positions were represented as rigid-body error transformations and analysed in SE(3), together with surface-distance metrics. The estimated transformations were propagated to CBCT-derived TMJ structures to quantify changes in condyle-fossa distance maps. The results demonstrate a systematic translational component and anisotropic variability of mandibular positioning error, with measurable propagation to simulated TMJ-space changes. The proposed framework provides an objective method for documenting planned and achieved mandibular configurations and for analysing positioning uncertainty in patient-specific splint workflows.

This work addresses the computational problem of generating reproducible projection-space observations from heterogeneous anatomical scenes whose components may undergo independent spatial transformations. We propose a transformation-driven framework for synthetic projection imaging from multimodal anatomical data and demonstrate it on mandibular-motion scenarios. In contrast to conventional Digitally Reconstructed Radiograph (DRR) approaches primarily designed for registration, projection realism, or rendering efficiency, the proposed formulation treats projection imaging as an observation process operating on an explicitly represented anatomical scene. Independently transformable volumetric and surface-based anatomical objects are embedded within a shared scene representation and propagated directly into projection space through explicit transformations. Projection geometry, acquisition modelling, material interpretation, and image presentation remain explicitly separated, enabling controlled exploration of methodological assumptions while preserving reproducibility and direct comparability between generated projections. Particular emphasis is placed on transformation-driven anatomical scenarios relevant to craniofacial analysis, including mandibular motion and therapeutic repositioning. Using a shared anatomical reference scene composed of CT/CBCT volumes, segmented structures, surface models, and auxiliary anatomical or therapeutic objects, the framework enables generation of directly comparable VirtualRTG projections from multiple anatomical configurations while preserving identical imaging assumptions. Rather than aiming at fully physically faithful radiographic simulation, the proposed approach provides a controllable and reproducible methodological environment for studying anatomy--projection relationships, motion observability, and transformation-aware imaging workflows.

Multimodal image registration plays a key role in creating digital patient models by combining data from different imaging techniques into a single coordinate system. This process often involves multiple sequential and interconnected transformations, which must be well-documented to ensure transparency and reproducibility. In this paper, we propose the use of transformation trees as a method for structured recording and management of these transformations. This approach has been implemented in the dpVision software and uses a dedicated .dpw file format to store hierarchical relationships between images, transformations, and motion data. Transformation trees allow precise tracking of all image processing steps, reduce the need to store multiple copies of the same data, and enable the indirect registration of images that do not share common reference points. This improves the reproducibility of the analyses and facilitates later processing and integration of images from different sources. The practical application of this method is demonstrated with examples from orthodontics, including the integration of 3D face scans, intraoral scans, and CBCT images, as well as the documentation of mandibular motion. Beyond orthodontics, this method can be applied in other fields that require systematic management of image registration processes, such as maxillofacial surgery, oncology, and biomechanical analysis. Maintaining long-term data consistency is essential for both scientific research and clinical practice. It enables easier comparison of results in longitudinal studies, improves retrospective analysis, and supports the development of artificial intelligence algorithms by providing standardized and well-documented datasets. The proposed approach enhances data organization, allows for efficient analysis, and facilitates the reuse of information in future studies and diagnostic procedures.

Digital technology plays a crucial role in designing customized medical devices, such as occlusal splints, commonly used in the management of disorders of the stomatognathic system. This methodological proof-of-concept study presents a computer-aided approach for designing and evaluating occlusal positioning splints. The primary aim is to demonstrate the feasibility and geometric accuracy of the proposed method at the preclinical stage. In this approach, a three-dimensional splint is generated using a transformation matrix to represent the therapeutic mandibular position. An experienced operator defines this position using a virtual patient model reconstructed from intraoral scans, CBCT, 3D facial scans, and a digitized plaster model. We introduce a novel method for generating splints that reproduces occlusal conditions in the therapeutic position and resolves surface conflicts through virtual embossing. The process for obtaining transformation matrices using dental tools and intraoral devices commonly employed in dental and laboratory workflows is described, and the geometric accuracy of both designed and printed splints is evaluated using profile and surface deviation analysis. The method supports reproducible, patient-specific splint fabrication and provides a transparent foundation for future validation studies, supporting multimodal image registration and quantification of occlusal discrepancies in research settings.

Multimodal imaging, including 3D modalities, is increasingly being applied in orthodontics, both as a diagnostic tool and especially for the design of intraoral appliances, where geometric accuracy is very important. Laser scanners and other precision 3D-imaging devices are expensive and cumbersome, which limits their use in medical practice. Photogrammetry, using ordinary 2D photographs or video recordings to create 3D imagery, offers a cheaper and more convenient alternative, replacing the specialised equipment with handy consumer cameras. The present study addresses the question of to what extent, and under what conditions, this technique can be an adequate replacement for the 3D scanner. The accuracy of simple surface reconstruction and of model embedding achieved with photogrammetry was verified against that obtained with a triangulating laser scanner. To roughly evaluate the impact of image imperfections on photogrammetric reconstruction, the photographs for photogrammetry were taken under various lighting conditions and were used either raw or with a blur-simulating defocus. Video footage was also tested as another 2D-imaging modality feeding data into photogrammetry. The results show the significant potential of photogrammetric techniques.

Methods are described of determining the dynamic occlusion surface based on dynamic sequences of mandibular motion, acquired with a dynamic scanner, and measurements acquired with the Zebris axiograph. The Zebris data is brought into register with multimodal imagery, using three corresponding transformations. This registration allows dense motion sequences to be simulated, which in turn allows occlusal conditions to be known at various stages of movement and the dynamic occlusal surface to be identified for the purposes of occlusal splint design.

The occlusal splint is one of the methods of treatment of discrepancies between the centric relation and maximal intercuspation (CR/MI), and other temporomandibular joint (TMJ) disorders. It is also a method of reducing the effects of bruxism. Designing an occlusal splint for a given relation between the maxilla and the mandible involves: creating partial surfaces, integrating them, and producing the splint on a 3D printer. The paper presents and compares some techniques used to design splint surfaces under a required therapeutic maxilla-mandible relation.

The purpose of this chapter is to discuss methods of acquisition, visualization and analysis of the dynamics of a complex biomedical system, illustrated by the human stomatognathic system. The stomatognathic system consists of the teeth and the skull bones with the maxilla and the mandible. Its dynamics can be described by the change of mutual position of the lower/mandibular part versus the upper/maxillary one due to the physiological motion of opening, chewing and swallowing. In order to analyse the dynamics of the stomatognathic system its morphology and motion has to be digitized, which is done using static and dynamic multimodal imagery like CBCT and 3D scans data and temporal measurements of motion. The integration of multimodal data incorporates different direct and indirect methods of registration - aligning of all the data in the same coordinate system. The integrated sets of data form 4D multimodal data which can be further visualized, modeled, and subjected to multivariate time series analysis. Example results are shown. Although there is no direct method of imaging the TMJ motion, the integration of multimodal data forms an adequate tool. As medical imaging becomes ever more diverse and ever more accessible, organizing the imagery and measurements into unified, comprehensive records can deliver to the doctor the most information in the most accessible form, creating a new quality in data simulation, analysis and interpretation.

Full automation of the designing process of an occlusal splint requires an algorithm to determine the boundary of the splint. For this purpose, the idea of tooth equator is frequently used. The task is to find the approximate level where the teeth are widest, and then cut off the shape of the splint there. The article presents methods for automatic estimation of the tooth equator, used to determine the splint boundary.

TheLuchowski, Leszek@Luchowski, Leszek Tomaka, Agnieszka Anna@Tomaka, Agnieszka Anna Skabek, Krzysztof@Skabek, Krzysztof Tarnawski, Michal@Tarnawski, Michał Kowalski, Przemyslaw@Kowalski, Przemysław present work proposes a computerised and algorithmic approach to a procedure which has traditionally been performed in hardware, by milling and polishing a physical object. While some fine physical final adjustments will still be necessary, we hope a digital approach will make the process less labor-intensive and allow for a more explicit positioning of the mandible.

The analysis of the condyle position in temporomandibular joint isTomaka, Agnieszka Anna@Tomaka, Agnieszka Anna Tarnawski, Michal@Tarnawski, Michał Pojda, Dariusz@Pojda, Dariusz crucial issue in differential diagnosis of bruxism and centric relation/maximal intercuspidation discrepancy or other temporomandibular joint disorders. The matter of importance are both static position of condyles during maximal intercuspidation and dynamics of mandible movement. The paper presents the method of evaluation of the dynamics of temporomandibular joint using the multiregistration of multimodal images: CBCT scans, virtual dental models and dynamic 3D photos of patient during the function. The mandible movements acquired with the optic 3D scanner are applied to the images gathered from CBCT, yielding the movement tracking of condyles in temporomandibular joint. Therefore low invasive 3D photo sequences registered with single high invasive CBCT yields the simulation of the high invasive imaging repetition. The anatomical evaluation of both the condyle position and occlusion condition during the movement may lead to the broaden TMJ diagnostics.

Orthodontic diagnosis uses the information obtained by different imaging modalities, but routine diagnosis of simple cases still relies on the orthopantomogram, the lateral cephalogram, planar photographs and dental cast; models. The article presents a method of virtual registration of 3D photographs (3D facial scans) with digital dental models. By deriving the idea from old gnathostatic models we explain the registration process with the use of registration objects - an equivalent of the traditional facial arch. Potential use of such registration to create a standardized patient dataset is discussed, in order to integrate the analysis of facial and dental models.

. The aim of this study of the cerebral cortex of 8 non-demented elderly subjects and of 17 subjects in the severe stage of Alzheimer's disease (AD) (Global Deterioration Scale stage 7/Functional Assessment Staging procedure stage 7a–f) was to examine the relationships between amyloid-β (Aβ) deposits and neurofibrillary degeneration. The study shows that neuronal processes with neurofibrillary changes are detectable in only a minority of fibrillar plaques: from 31% to 49% of fibrillar plaques within frontal, temporal, parietal, limbic, occipital, and insular cortices. The correlations observed between the numerical densities of neurons with neurofibrillary tangles (NFTs) and the densities of Thioflavin-S-positive fibrillar plaques with neurofibrillary changes ( r =0.61; P <0.01) indicate that neurofibrillary pathology in neocortical plaques reflects the topography and rate of neurofibrillary changes in neocortical neurons. The accumulation of abnormally phosphorylated tau in only some plaques indicates that fibrillar Aβ enhances paired helical filament accumulation locally only in dystrophic neurites already involved in neurofibrillary degeneration. The lack of correlation between the number of neurons with neurofibrillary changes and the number of all Thioflavin-S-positive fibrillar plaques (with and without neurofibrillary changes) suggests that β-amyloidosis does not contribute to initiation of neurofibrillary degeneration in neurons.

A morphometric study of amyloid-beta-positive plaques in the neocortex of eight non-demented people from 68 to 82 years of age and 17 subjects with late-stage Alzheimer disease (GDS stage 7/FAST stages 7a-f) from 73 to 93 years of age shows a shift from prevalence of fibrillar plaques to prevalence of nonfibrillar plaques. In the aged, non-demented subjects, about 4/mm^2 plaques are detectable in the neocortex, and the majority are fibrillar plaques. Specifically, 64% found to be classical fibrillar and Thioflavin-S-positive bright primitive plaques. A lower percentage of pale primitive plaques (35%) relatively small proportion of plaques that are poor in thioflavin S-positive fibrils. The numerical density of plaques in the severe stage of AD increases to about 41/mm^2. Severely demented subjects appear to maintain an active process of fibrillar plaque formation. This is reflected in the presence of 3% bright primitive plaques. Severely demented subjects also manifest plaque degradation, reflected in the presence of 22% and 48% percentages of classical fibrillar plaques in non-demented subjects and in the end stage of disease suggest that once activated, the process of fibrillar plaque formation persists at a somewhat stable rate during the whole course of brain amyloidosis.

The current study describes both Aβ and tau abnormalities that accumulate in the brains of aged (16–21 years), but not young (<4 years) clinically characterized cats. Diffuse plaques that were morphologically different from what is typically observed in the human brain could be detected with 4G8 (Aβ17–24) or an Aβ1–42-specific antibody but not with N-terminal Aβ or an Aβ1–40-specific antibody. SELDI-TOF mass spectrometry experiments indicated that cat brain Aβ consisted almost entirely of Aβ1–42. Markers of tau hyperphosphorylation (AT8 and PHF-1) labeled a subset of neurons in two aged animals. In the hilus of the hippocampus, a subset of AT8 positive neurons showed a sprouting morphology similar to that observed in human brain. Western blot analysis with antibodies against hyperphosphorylated tau indicated that tau is hyperphosphorylated in the aged cat and contains many of the same epitopes found in Alzheimer's disease (AD) brain. Thus, the aged cat brain develops AD-related lesions with important morphological and biochemical differences compared to human brain.