Search Results (286)

Background/Objectives: This finite element analysis (FEA) assessed stress distribution in the tooth and dentin within an intact periodontium under 4 N of force and five orthodontic movements (intrusion, extrusion, rotation, tipping, and translation), using four failure criteria commonly used in numerical dental studies. Secondly, differences between brittle- and ductile-like failure criteria were found, and the most accurate criterion was determined. Additionally, movements more prone to inducing external orthodontic root resorption were assessed. Methods: Using nine 3D models of the second lower premolar, 180 numerical simulations were performed. The models were anatomically accurate based on CBCT scans. FEA employed the brittle-like Maximum Principal (MaxP), Minimum Principal (MinP), and ductile-like Von Mises (VM) and Tresca (T). Results: The results showed that tipping was less prone to external orthodontic root resorption than translation, extrusion, intrusion, and rotation, which showed areas of high stress concentration in the cervical third of the root. High-stress areas were visible only when the dentin-pulp-NVB components were separately analyzed, and not when the entire tooth structure was assessed. Only by correlating the qualitative with the quantitative results could the difference between brittle-like and ductile-like failure criteria be seen. Conclusions: In total, 4 N of applied orthodontic force can induce limited islands of external orthodontic root resorption (intrusion–extrusion on the vestibular side, rotation–translation on the lingual and distal–lingual sides). The ductile-like failure criteria maintained the accuracy of the results across all FEA simulations, while the brittle-like criteria showed various quantitative and qualitative inconsistencies. Full article

Prolonged water injection in unconsolidated sandstone reservoirs can induce pore rearrangement and modify flow pathways, thereby affecting reservoir performance. However, quantitative characterization of pore evolution in both temporal and spatial dimensions remains limited. This study investigates the mechanisms of pore-structure evolution during extended injection through a series of multi-scale experiments. Scanning electron microscopy and X-ray diffraction analyses were employed to compare mineral composition and microstructural characteristics before and after injection, while in situ nuclear magnetic resonance (NMR) monitoring captured the dynamic evolution process, enabling pore-size classification from T₂ spectra and fractal assessment of structural complexity. Segmented NMR measurements at different distances further resolved spatial heterogeneity. The results show that prolonged water injection reduced permeability by 10.4–32.1%, whereas porosity exhibited only minor variation, indicating that the decline in flow capacity is primarily controlled by pore–throat structural adjustment rather than pore volume loss. Mineralogical redistribution and fine-particle migration decreased the median pore radius by 21.5–51.8% and the micropore fractal dimension by 23.8–76.5%, with stronger responses observed at higher permeabilities, while meso- and macropore fractal dimensions remained nearly unchanged, indicating preferential modification of micropores with preservation of the main connected flow framework. Consistently, NMR responses reveal pronounced spatial heterogeneity along the flow direction. The NMR signal changes at the injection end were 11.2–18.4% and 7.7–21.7% during the early and intermediate stages, respectively, both exceeding those at the distal end (2.9–12.4% and 1.9–17.1%). These results indicate a downstream-attenuating structural modification gradient. The findings provide new insights into pore-structure evolution during prolonged water injection and offer a scientific basis for optimizing water-injection strategies in unconsolidated sandstone reservoirs. Full article

Background/Objectives: This technical report introduces an innovative hybrid digital workflow that integrates diagnostic plaster-cast scanning with intraoral scanning to produce an accurate 3D-printed model for fabricating distal-extension removable dental prostheses (RDPs). Methods: The technique aims to overcome the challenges of reproducing the mobile mucosa in free-end saddles, a critical factor for denture base accuracy and stability. The workflow began with conventional clinical procedures, including clinical examination, impression-making, and cast surveying. After performing the required mouth preparations according to the prosthetic design, the diagnostic cast was digitized and selectively modified to allow intraoral rescanning. The prepared teeth were then scanned intraorally and merged with the digitalized cast, producing a refined virtual model for CAD-based metal framework design. The framework was digitally designed, 3D-printed to verify adaptation, and cast in cobalt–chromium. Standard RDP fabrication steps were followed, including intraoral framework try-in, fabrication of acrylic bases, occlusal registration, tooth arrangement, and functional and esthetic try-in. The final prosthesis was installed and adjusted without the need for an additional impression. Results: This hybrid workflow enabled a highly accurate reproduction of the distal extension region, outperforming models derived solely from direct intraoral scanning. By digitally capturing the physiological morphology of the mobile mucosa, the method eliminates the need for the traditional altered-cast technique, reducing clinical time, technical sensitivity, and material costs. Conclusions: The proposed approach enhances denture base accuracy, improves adaptation, and promotes more uniform occlusal load distribution in free-end RDPs. This streamlined and reproducible digital protocol offers a clinically relevant advancement, with potential to improve prosthesis stability and long-term outcomes. Full article

Background: Subchondral cysts at the ulnar corner of the lunate are frequently encountered in patients with distal radius fractures. We hypothesized that the presence of these lunate subchondral cysts may be associatedwith decreased cortical bone density due to limited load translation. Consequently, this could lead to lunate fossa collapse and increased ulnar variance following fracture fixation. Methods: A retrospective analysis was performed on 176 patients who underwent open reduction and internal fixation using the Double-tiered Subchondral Support (DSS) procedure between May 2014 and June 2017. Twenty-eight patients identified with lunate subchondral cysts on preoperative CT scans were selected as the study group. A control group of 28 patients without cysts was selected using matched-pair analysis, controlling for gender, age, fracture classification, and follow-up period. Results: The mean change (delta) in ulnar variance was 0.191 mm in the cyst group, which was less than the 0.233 mm observed in the control group; however, this difference was not statistically significant (p = 0.557). Regarding ulnolunate distance, the cyst group showed a mean change (delta) of 0.991 mm, while the control group showed a change of 1.123 mm. This difference was also not statistically significant (p = 0.681). Conclusions: Although it was hypothesized that lunate subchondral cysts might limit load translation to the radius and compromise cortical bone density—potentially affecting fracture healing and the maintenance of reduction—our statistical analysis did not support this hypothesis. The presence of lunate subchondral cysts did not significantly increase the risk of lunate fossa collapse or ulnar variance progression compared to the control group. Full article

Objectives: To determine the most favourable Micro-Implant (MI) insertion site along the mandibular buccal shelf (MBS), using Cone Beam Computed Tomography (CBCT). Methods: This retrospective study assessed CBCT scans from 90 Portuguese patients (32 males and 58 females, aged 14 to 40 years). Paired MBS sites were determined. Comparative and correlation analyses were performed at p < 0.05. Results: A significant increase in MBS width was observed from the mesial to the distal direction (p < 0.001). Conversely, both the MBS steepness and cortical bone thickness significantly decreased from mesial to distal (p < 0.001). Significant negative correlation was also found between age and cortical bone thickness adjacent to the distobuccal cusp and distal tangent of both mandibular second molars (r ≤ −0.373, p ≤ 0.007). Furthermore, significant asymmetric differences were identified between the right and left MBS steepness as well as in the paired cortical bone thickness at the mesiobuccal cusp, buccal groove, and distobuccal cusp of the mandibular second molar (p ≤ 0.016). Conclusions: The results indicate that although there are sufficient MBS width and cortical bone thickness, vestibular to the mandibular second molar for MI insertion, the sites towards the distal root of the mandibular second molar are more favourable when considering MBS steepness. These findings are consistent for both sexes and apply to young and old individuals. Full article

Background/Objectives: Proton therapy has emerged as an advanced radiotherapy modality due to its unique physical dose distribution and its distinct radiobiological properties. The finite range of protons in tissue enables highly conformal dose delivery with minimal exit dose, significantly reducing irradiation of surrounding normal tissues compared to photon-based radiotherapy. Beyond these physical advantages, proton beams exhibit a spatially varying linear energy transfer that increases toward the distal edge of the spread-out Bragg peak, leading to clustered and complex DNA damage that is more difficult for cancer cells to repair. Methods: This review integrates experimental, computational, and clinical evidence to examine how proton-induced DNA damage, relative biological effectiveness, oxygen effects, and non-targeted responses contribute to tumor control and normal tissue sparing. Results: Comparative analyses with photon intensity-modulated radiotherapy demonstrate consistent reductions in acute and late toxicities across multiple tumor sites, particularly in pediatric patients and in tumors located near critical organs. The review also discusses emerging technologies, including pencil beam scanning, image-guided and adaptive proton therapy, compact accelerator systems, and ultra-high dose rate FLASH proton therapy, which collectively aim to enhance treatment precision, biological effectiveness, and accessibility. Conclusions: Together, these developments support proton therapy as a rapidly evolving modality with significant potential to improve therapeutic outcomes in modern oncology. Full article

Background/Objectives: The presence of untreated second mesio-buccal canals (MB2) in maxillary first molars is usually associated with endodontic treatment failure. Previous CBCT-based investigations have evaluated the quality of root canal fillings and the prevalence of apical lesions in endodontically treated teeth. However, evidence specifically addressing untreated MB2 canals and their association with apical periodontitis remains limited. Therefore, the aim of this cross-sectional study was to evaluate the prevalence of unfilled MB2 canals in endodontically treated maxillary first molars and their association with apical periodontitis. Methods: CBCT scans of 75 patients from an endodontic practice were retrospectively analyzed. Maxillary first molars (teeth 16 and 26) were evaluated for the presence and filling status of root canals (MB1, MB2, palatal, distal) and the presence of periapical radiolucency using the CBCT periapical index. Two calibrated examiners independently assessed all images. The association between unfilled MB2 canals and apical periodontitis was analyzed using chi-square tests, and odds ratios with 95% confidence intervals were calculated. Results: The mean patient age was 53.4 ± 15.5 years (range: 14–80). An MB2 canal was present in 84% (63/75) of eligible teeth. Among teeth with an MB2 canal, only 20.6% (13/63) were endodontically filled, while 79.4% remained untreated. Apical periodontitis was observed in 65.3% (49/75) of all teeth. A significant association was found between unfilled MB2 canals and apical periodontitis (p < 0.001), with an odds ratio of 0.095 (95% CI: 0.022–0.402), indicating that filled MB2 canals significantly reduced the possible risk of periapical pathology. Conclusions: A high prevalence of unfilled MB2 canals was observed in this German population (79.4%). Furthermore, unfilled MB2 canals were strongly associated with apical periodontitis. Therefore, clinicians should utilize all available diagnostic tools, including CBCT and dental microscopes, to maximize MB2 canal identification and improve endodontic treatment outcomes. Full article

The microstructure and ultrastructure of the sperm of Japanese eel, Anguilla japonica, artificially induced with weekly injections with carp pituitary (CP) and human chorionic gonadotropin (HCG), was studied, and milt from 10 out of 20 mature fish was collected. Two distinct morphological structures of A. japonica sperm had been observed with optical microscopy. The cell nucleus of one type of sperm was round or nearly round, the sperm was smaller in size, with 2.57 ± 0.62 μm of the long diameter of the cell nucleus, 2.11 ± 0.59 μm of the short diameter, and 37.35 ± 7.71 μm of the flagellum length. Another type was the eyebrow-shaped sperm, the sperm was relatively larger in size, with 7.66 ± 1.09 μm of the long axis, 2.54 ± 0.46 μm of the short axis, and 38.26 ± 9.02 μm of the flagellum length. By means of scanning electron microscopy (SEM) and transmission electron microscopy (TEM), the anterior end of the round sperm lacked an acrosomal structure. The implantation fossa was located in the center of the base of the sperm head, and it was in the shape of a channel along the long axis of sperm. The centriolar complex was situated within the implantation fossa. There were 2–3 mitochondria distributed at the basal end of the nucleus. Sperm flagellum prolongated from the sleeve cavity, and the initial part of axoneme connected to the distal end of basal body. The axoneme displayed a typical “9 + 2” pattern. There was a spherical structure in the curving area for eyebrow-shaped sperm, and the axoneme formed a “9 + 0” pattern. The discovery of two different types of sperm in the Japanese eel has provided new perspectives for research on its artificial reproduction. Full article

Background/Objectives: For centuries, humans have employed animal models to progress biomedical science, to understand pathological and biological processes, and to develop and test drugs, vaccines, and surgical techniques. In the field of urology, Sampaio and his colleagues from Brazil were the pioneers in proposing that the porcine model is the most accurate representation of the human kidney. We aim to describe the relevant urinary anatomy of female Landrace pigs based on endoscopy and computed tomography (CT) scans and compare differences between the urinary anatomy of pigs and humans. Methods: Four white Landrace female pigs were used for the study: two for CT imaging and two for endoscopic assessment. CT-urograms were performed using a 64-channel tomography machine with 0.625 mm thick slices. For the endoscopic procedure, the intravaginal urethral meatus was cannulated using a cystoscope, followed by complete urethrocystoscopy. The ureteric orifices were then cannulated, and a retrograde pyelogram was performed, followed by ureterorenoscopy. The analyses were performed using SPSS (Version 28), and simulated data was created using R (version 3.5.0), with the significance set at p ≤ 0.05. The data obtained from two pigs was used to simulate an empirical data with 500 observations, using the mean and standard deviations from our n = 2 to produce a random normal distribution. Results: CT and endoscopic findings showed two multirenculate multipapillate kidneys, each receiving blood supply from a single renal artery that is further divided into cranial and caudal branches. The delayed phase of the urogram showed distal ureters passing posterior to the bladder and emptying into the bladder at the base. Urethroscopy revealed an intravaginal urethral meatus ventral to the anus, positioned midway between the mucocutaneous junction of the vulva and the cervix. Endoscopic view of the bladder neck showing patulous ureteric orifices at the bladder neck with no distinct interureteric ridge or trigone. Retrograde pyelogram showed a Group B drainage pattern in both pigs. Conclusions: While there are numerous similarities between the urinary systems of humans and pigs, there are important subtle differences that urologists and researchers need to be mindful of before using the porcine model for urological research and training. Full article

Background: Metalloproteinases (MMPs), together with their tissue inhibitors (TIMPs), regulate the extracellular matrix (ECM) in various tissues. MMP-2 and TIMP-2 maintain this process in renal tissue. An imbalance in the MMP-2/TIMP-2 ratio alters the abundance and proportions of specific extracellular matrix components, leading to kidney fibrosis. We aimed to assess differences in the morphometric parameters of the kidney and the immunohistochemical (IHC) expression of MMP-2 and TIMP-2 in kidney biopsies according to their fibrotic state. Methods: The histological slides were scanned using the 3DHISTECH Pannoramic MIDI II Scanner, and the resulting digital images of the sections were analyzed using Pattern Quant software; the morphometric analyses were performed with the Slide Viewer application. Results: In the current manuscript, we have investigated the significant enlargement of the diameter of the urinary space and renal corpuscle, as well as the reduced height of the epithelial lining of the proximal and distal convoluted tubules, of grafted kidneys with fibrosis when compared to the non-fibrotic kidneys. Moreover, we have noticed a rising MMP-2/TIMP-2 ratio in the immunohistochemical reaction in the renal tissue of fibrotic grafted kidneys in comparison to healthy kidneys. Conclusions: These results suggest that the MMP-2/TIMP-2 ratio, together with the lower inhibition of MMP-2, may promote an increased extracellular matrix remodeling, which accompanies the development of fibrosis. Full article

Objectives: This study aims to evaluate the predictability of Clear Aligner Therapy (CAT) in deep bite correction and Spee Curve flattening by comparing final intraoral scans with planned outcomes in ClinCheck. Methods: STL files from pre-treatment, post-treatment (first aligner cycle), and planned final positions of 18 patients (12 females; 6 males; mean age 30.9 ± 12.3 years) were analyzed. The software Medit Link (version 3.4.4) was used to measure overbite as the vertical distance between the incisal edges of the maxillary and mandibular central incisors and the Curve of Spee in both arches by drawing a reference line between the most distal molar and the central incisor on each side, recording the perpendicular distance from the distal cusp. Measurements were repeated on post-treatment and ClinCheck STL files. Data analysis was performed using a Student’s t-test (p = 0.05) to compare the expected and actual measure variations and intraclass correlation coefficient (ICC) to assess aligner predictability. Results: A significant discrepancy was observed in overbite correction (55% achieved), with a significant difference between expected and actual outcomes (p = 0.0001). Moderate differences were noted for the lower Spee Curve (62% achieved), while the upper Spee Curve showed 86% of the expected change. ICC values were moderate for overbite and lower Spee Curve, and good for the upper Spee Curve. Conclusions: ClinCheck overestimates deep bite correction. Upper Curve of Spee flattening is highly predictable, while the lower curve flattening has lower predictability. Full article

Background/Objectives: Marginal fit is a key determinant of the clinical performance of CAD/CAM (Computer-Aided DesignComputer-Aided Manufacturing) inlay restorations. This in vitro study compared the vertical marginal gap (VMG) of three chairside CAD/CAM inlay materials—VITA Enamic, CEREC Tessera, and Celtra Duo—using scanning electron microscopy (SEM) under a standardized digital workflow. Methods: Standardized Class I inlay preparations were performed in 15 extracted human molars (n = 5/material). Restorations were fabricated using a chairside workflow (Primescan intraoral scanning, CEREC 5.3 design, Primemill milling) followed by material-specific surface treatment and cementation with a self-adhesive resin cement. VMG was measured on SEM micrographs (500× for quantitative measurements; 200× for orientation) at three sites (mesial, central, distal), with three points per site (nine points/tooth; 135 point measurements). Triplicate points were averaged to site-level means and analyzed using a linear mixed-effects model (fixed effects: material, site, material × site; random intercept: tooth), Type II ANOVA, and Tukey-adjusted pairwise comparisons. Results: Mean VMG values were lowest for Celtra Duo (8.09 ± 1.98 µm), followed by VITA Enamic (27.90 ± 29.76 µm) and CEREC Tessera (32.72 ± 21.80 µm). The model indicated an overall effect of material (F(2,36) = 3.51, p = 0.040), whereas site and material × site effects were not significant. Tukey-adjusted pairwise comparisons did not reach statistical significance. Conclusions: Within the standardized chairside workflow evaluated, an overall material effect on VMG was detected, but pairwise separation was inconclusive in this sample with overlapping distributions. Celtra Duo showed smaller VMG values with narrower dispersion in overall per-tooth means, while VITA Enamic and CEREC Tessera showed wider and overlapping distributions; all group means were below commonly cited clinical acceptability ranges for marginal gap. Full article

A supplemental description of Lamproglena barbicola Fryer, 1961 is provided based on specimens collected from the gills of Labeobarbus altianalis (Boulenger, 1900) from the Nyando River, Lake Victoria Basin, Kenya, using an integrated approach of scanning electron microscopy (SEM) and molecular analysis (18S, 28S rDNA, and cox1 gene regions). Morphologically, the specimens conform to L. barbicola and closely resemble Lamproglena hoi Dippenaar, Luus-Powell & Roux, 2001; however, SEM revealed a previously undescribed feature on the uniramous antennule in L. barbicola, namely indistinctly three-segmented, tapering from a broad base to the apex, basal segment much longer than distal, comprising 14 setae of varying sizes, ventral laterally, absence of distinctive anterior fringe of setae on the antennule, as well as several characters that differentiate L. barbicola from L. hoi, including 5 setae at the basal endopod of leg one, five cuticular protuberances in the oral region, 19 setae on the basal antennular segment, and 10 setae on the distal segment, with 1 seta on each ramus. The phylogenetic analysis confirms L. barbicola as a sister taxon of L. hoi, supporting their close relationship. The genetic divergence presented as the uncorrected genetic p-distances between L. barbicola and L. hoi are 23.1% and 0.45% for cox1 and 28S rDNA regions, respectively, with observed nucleotide differences of 145 and 3 bp between the sequences, respectively. There was no interspecific variability detected in the 18S rDNA sequences. This study provides novel molecular sequences and the first high-resolution SEM images, which reveal additional taxonomic features for L. barbicola, establishing a robust reference for future identification. Full article

This study compares the two (2D)- and three-dimensional (3D) accuracy of tooth reduction depths in porcelain laminate veneer prepared using conventional and 3D-printed guide techniques. Forty 3D-printed maxillary casts were divided into four groups: freehand (FH) (n = 10), silicone guide (SG) (n = 10), cross-shaped 3D-printed guide (3D_C) (n = 10), and stackable 3D-printed guides (3D_S) (n = 10). Butt-joint veneer preparation was performed on the left central incisor. Two-dimensional analysis was performed to assess trueness using mean absolute differences (MADs) from the planned depth at eight designated points, while precision was compared within groups. Three-dimensional analysis evaluated trueness by superimposing post-preparation scans with reference casts and precision via intra-group superimposition, with deviation errors measured using the Root Mean Square (RMS) method. One-way ANOVA and Bonferroni post hoc tests were used (α = 0.05). In 2D analysis, 3D_S exhibited a significantly lower MAD than FH at most of the measured points (p < 0.05), more accurate incisal reduction at mesial and distal points compared to 3D_C (p < 0.001), and more accurate mesial (p = 0.011) and distal (p = 0.001) cervical margin preparation than SG. In the 3D trueness assessment, 3D_S exhibited significantly lower deviation errors than FH (p < 0.001) and SG (p = 0.012) while also achieving the highest overall 3D precision with the lowest RMS (0.067 ± 0.013), followed by 3D_C (0.086 ± 0.019). Veneer preparation guided by a stackable 3D-printed guide resulted in more accurate tooth reduction depths compared to the other three techniques. Full article

Mucus plugs are airway-obstructing accumulations of inspissated secretions frequently observed in obstructive lung diseases (OLDs), including chronic obstructive pulmonary disease (COPD), severe asthma, and cystic fibrosis. Their presence on chest CT is strongly associated with airflow limitation, reduced lung function, and increased mortality, making them emerging imaging biomarkers of disease burden and treatment response. However, manual delineation of mucus plugs is labor-intensive, subjective, and impractical for large cohorts, leading most prior studies to rely on coarse segment-level scoring systems that overlook lesion-level characteristics such as size, extent, and location. Automated plug-level quantification remains challenging due to substantial heterogeneity in plug morphology, overlap in attenuation with adjacent vessels and airway walls on non-contrast CT, and pronounced size imbalance in clinical datasets, which are typically dominated by small distal plugs. To address these challenges, we developed and validated a simulation-driven, annotation-free deep learning framework for automated detection and segmentation of airway mucus plugs on non-contrast chest CT. A total of 200 COPD CT scans were analyzed (98 plug-positive, 83 plug-negative, and 19 uncertain). Synthetic mucus plugs were generated within segmented airways by transferring voxel-intensity statistics from adjacent intrapulmonary vessels, preserving realistic morphology and texture while enabling controlled sampling of plug phenotypes. An nnU-Net trained exclusively on synthetic data (S-Model) was evaluated on an independent, expert-annotated test set and compared with an nnU-Net trained on manual annotations using 10-fold cross-validation (M-Model). The S-Model achieved significantly higher detection performance than the M-Model (sensitivity 0.837 [95% CI: 0.818–0.854] vs. 0.757 [95% CI: 0.737–0.776]; 1.91 false positives per scan vs. 3.68; p < 0.001), with performance gains most pronounced for medium-to-large plugs (≥6 mm). This simulation-driven approach enables accurate, scalable quantification of mucus plugs without voxel-wise manual annotation in thin-slice (<1.5 mm) non-contrast chest CT scans. While the framework could, in principle, be extended to other annotation-limited medical imaging tasks, its generalizability beyond this COPD cohort and imaging protocol has not yet been established, and future work is required to validate performance across diverse populations and scanning conditions. Full article