Higher Bone Density Research Articles

Comprehensive Analysis of the Association Between Sex Hormones and Body Mass Components Among Men Adults: Results From a Large Population-Based Study.

As the human body ages, adverse body composition status such as sarcopenia and obesity become obvious phenotypes which can cause numerous health problems. We aimed to comprehensively investigate the association of sex hormones and body mass components in adult men of various age groups. We analysed national representative population data from the US National Health and Nutrition Examination Survey. Generalized linear model regression analyses were used to evaluate the association between sex hormones (total testosterone [TT], bio-available testosterone [BT], sex hormone-binding globulin [SHBG], estradiol [E2] and testosterone to estradiol ratio [T/E ratio]) and body mass components (weight, body mass index (BMI), total lean mass, appendicular lean mass, bone mineral content, total fat and trunk fat). The collection and testing time of blood samples were not fixed and there was no strict fasting, but in subsequent analysis we used statistical methods to minimize the impact of random testing. After screening for inclusion and exclusion, 3759 male participants aged 20-85 years old were included in this study. Higher levels of TT, SHBG, BT and T/E ratios were significantly associated with higher total lean mass, appendicular lean mass and bone mineral content, while lower weight, BMI, total fat and trunk fat. For E2 levels in men, we found an opposite trend, with higher E2 levels significantly associated with lower total lean mass and appendicular lean mass, and higher weight, BMI, total fat and trunk fat. Notably, in subgroup analysis, the results showed that there were significant interaction effects of age and smoking history in the association between sex hormones and body mass components. Higher TT levels, BT levels, SHBG levels and T/E ratios are associated with lower body weight and improved body composition in young adult men (characterized by higher lean body mass, higher bone density and lower fat mass). The relationship is especially pronounced among relatively young, nonsmoking men.

Image Quality Comparison of Three 3D Mobile X-Ray Imaging Guidance Devices Used in Spine Surgery: A Phantom Study.

An image-quality CT phantom was scanned with three different 3D X-ray imaging guidance devices in the operating theatre: O-Arm, Loop-X, and Airo TruCT. Default acquisition and reconstruction parameters for lumbar spine procedures were used on each device. The tube current was set to a dose level of around 27 mGy. A task-based image quality assessment was performed by calculating the noise power spectrum (NPS) and task transfer function (TTF). A detectability index (d') was calculated for three simulated bone lesions. The noise magnitude of the O-Arm was higher than the Airo TruCT, and the Loop-X had higher noise than the Airo TruCT. The highest average NPS frequency was for the O-Arm images, and the lowest was for the Loop-X. The TTFs at 50% values were similar for the Airo TruCT and Loop-X devices. Compared to Airo TruCT, the TTF at 50% value increased with the O-Arm by 53.12% and 41.20% for the Teflon and Delrin inserts, respectively. Compared to Airo TruCT, the d' value was lower with Loop-X by -26.73%, -27.02%, and -23.95% for lytic lesions, sclerotic lesions, and high-density bone, respectively. Each 3D-imaging spine surgery guidance device has its own strengths and weaknesses in terms of image quality. Cone-beam CT systems apparently offer the best compromise between noise and spatial resolution for spine surgery.

The Impact of FDA-Approved Novel Agents for Steroid-Refractory Chronic Graft vs. Host Disease on Treatment Patterns and Outcomes—A Single-Center Longitudinal Cohort Analysis

Objectives—chronic graft vs. host disease (cGVHD) is associated with substantial morbidity and mortality. We aimed to analyze advances in treatment strategy and outcomes during the last decade due to the incorporation of novel immunosuppressive therapy (IST) drugs in the armamentarium. Methods—we retrospectively analyzed all patients > 18 years with cGVHD after their first hematopoietic cell transplantation (HCT) between 2012 and 2020 (n = 91), divided into three treatment periods: 2012–2014, 2015–2017, and 2018–2020 (groups 1, 2, and 3, respectively). Results—mean cumulative steroid dose and dose/total cGVHD-treatment days was lower in groups 2–3 compared to 1 (p = 0.008 and p = 0.042, respectively). The median IST-free survival was 79 (95%CI54–94) months, with more patients in group 3 (47% (95%CI 25–54%) discontinuing IST at 3 years, p = 0.1). Groups 2–3 compared to 1 had better glycemic control (p < 0.01), higher bone density (p = 0.06), and fewer cardiovascular events. The number of admissions/patient dropped from 0.7/year in group 1 to 0.24/year and 0.36/year in groups 2–3, respectively (p = 0.36). Employment reintegration was higher in groups 2–3 compared with 1 (p = 0.05) and so was earlier return to work (p = 0.01). There were no differences in survival outcomes. Conclusions—the incorporation of novel agents appears to be associated with reduced overall steroid burden, improved cGVHD control, and fewer long-term side effects.

CT-Based Evaluation of Volumetric Posterior Pelvic Bone Density with Implications for the Percutaneous Screw Fixation of the Sacroiliac Joint.

Background: Operative treatment of fragility fractures of the pelvis has become a gold standard. Preoperative planning, including the assessment of the pathway for iliosacral screws, is crucial. The anchorage of the screw depends on the bone quality. Some recent studies have concentrated on assessing bone mineral density (BMD) with the use of Hounsfield unit (HU) values obtained from CT scans. The aim of the present study is to determine the best sacral levels of S1-S3 on the pathway of iliosacral screws for sacroiliac joint fixation. Methods: Patients admitted to the Independent Public Healthcare Center in Rypin between 1 of September and 1 of December in 2023, who had CT scans of the pelvis performed on them for different reasons, were included in this study. In total, 103 patients-56 men and 47 women-were enrolled in the study and consecutively separated into two groups of different ages: 18-60 years old (group A) and above 60 years old (group B). The volumetric bone density expressed in HU values was measured with sacral levels of S1, S2 and S3. Apart from the bodies of sacral vertebrae S1-S3, our measurements involved the ala of the ilium in the vicinity of the sacroiliac joint and the wing of the sacrum. All the measurements were performed on the pathway of presumptive iliosacral screws to stabilize the sacroiliac joint. Results: In group A (58 patients) the highest bone density in sacral bodies was found in S1 that gradually decreased to S3, while the opposite tendency was demonstrated in the ala of ilium. The HU values in the wing of the sacrum did not display statistical significance. In group B (45 patients), the highest bone density was also found in the sacral body S1 that decreased toward S3 but in the ala of ilium, the highest bone density was found with level S1 and lowest with level S2. In both groups, the highest bone density referred to the wing of the sacrum. Conclusion: While the perfect construct for posterior pelvic ring fixation remains unclear, our findings may imply that sacroiliac joint screws inserted into the wing of the sacrum of greater bone density could provide much more successful fixation in comparison to those anchored in the body of sacral vertebra of lesser bone density.

Mapping optimal orthodontic implant sites in the palate using cone-beam computed tomography.

To measure the palatal soft tissue thickness and cortical bone density to determine safe regions for the placement of orthodontic mini-implants and to examine the influence of sex and age on soft tissue thickness and cortical bone density. Cone-beam computed tomography images of 42 patients (22 males and 20 females), including 21 adults and 21 adolescents, were examined in this study. The palatal soft tissue thickness and cortical bone density were measured at the coronal planes between the premolars (P4-5), between the second premolars and first molars (P5-6), and between the first molars and second molars (P6-7). The thickness of the soft tissue revealed similar coronal planes, but the bone density varied. The mean thickness was 3.8 mm at 0°-60° and 1.5 mm at 60°-90°. P4-5 had the highest bone density (>600 HU), decreasing toward P6-7 (<600 HU). Bone density decreased from 90° to 0° coronally, whereas the soft tissue thickness increased. Age, sex, and their interaction affected bone and soft tissues. In general, areas with a high bone density tended to have thin soft tissue coronally, thus the preferred implant site tends to be more anterior to the P4-5 plane and closer to 60°-90°. Considering individual variances, mapping of the recommended regions for palatal mini-implants is suggested.

Correlation between Bone Marrow Microvascular Density, Angiogenesis Factors and Bortezomib Resistance in Multiple Myeloma

To investigate the correlation between bone marrow microvascular density, angiogenesis factors and bortezomib resistance in multiple myeloma (MM). The data of 200 patients with MM treated in our hospital from January 2020 to August 2023 were retrospectively analyzed, and the patients with MM were divided into drug-resistant group(n=68) and non-drug-resistant group(n=132) according to their drug resistance during bortezomib treatment. The univariate and multivariate logistic analysis were used to screen the independent influencing factors of bortezomib resistance in MM patients during treatment. The receiver operating characteristic (ROC) curve and clinical decision curve (DCA) were used to evaluate the predictive performance and clinical application value of the risk prediction model, the consistency between the actual incidence rate and the predicted incidence rate was judged by validating the calibration chart, and the goodness-of-fit of the model was judged by H-L test. 68 of the 200 MM patients developed resistance and poor clinical efficacy during bortezomib treatment, and the clinical resistance rate of bortezomib was 34.0%. The results of multivariate analysis showed that high bone marrow microvessel density (MVD) and high bone marrow supernatant VEGF, HGF, and bFGF expression levels were independent risk factors for bortezomib resistance in MM patients (P < 0.05). The area under the ROC curve (AUC) of the model jointly constructed by bone marrow MVD, serum VEGF, HGF, bFGF and TNF-α levels was 0.924, and its sensitivity and specificity were 92.6% and 78.8%, which were higher than those of the bone marrow MVD model (AUC=0.743) and the vasogenesis factor model (AUC=0.878). The calibration curve of the joint prediction model was close to the standard curve, indicating that the model is more consistent. The results of H-L goodness -of - fit test showed χ2=14.748， P =0.164, the joint prediction model had a good fit. The DCA curve showed that the clinical net benefit of intervention in the range of 0.0~1.0 was greater than that of full intervention and no intervention. The prediction model based on bone marrow MVD and vasogenesis factors (VEGF, HGF, bFGF) in MM patients has higher clinical evaluation performance and predictive value.

Autologous platelet concentrates in alveolar ridge preservation: A systematic review with meta-analyses.

In order to evaluate the therapeutic advantages of various autologous platelet concentrates (APC) as a single biomaterial during alveolar ridge preservation (ARP), a systematic review with meta-analyses was conducted. PubMed, EMBASE, Web of Science, and Scopus were screened for randomized controlled trials (RCTs) that were released prior to 2024. The selected papers compared an APC with either unassisted healing (blood clot) or another biomaterial during ARP (third molars were not included). The outcome parameters included alveolar bone dimension alterations, soft tissue healing, and post-op pain intensity. The search yielded 35 papers (33 studies), one applying platelet-rich plasma (PRP), six using plasma rich in growth factors (PRGF), and 28 using leukocyte- and platelet-rich fibrin (L-PRF). These studies showed a large heterogeneity (e.g., outcome parameters, timing, surgical approach, and inclusion criteria), which hindered drawing strong conclusions. In most studies, however, ARP with PRP, PRGF, and L-PRF alone produced faster soft tissue healing, less post-extraction pain, less alveolar ridge resorption, more socket bone fill, and a higher bone density when compared to unassisted (spontaneous) healing. The ultimate benefit appears to be significantly influenced by the surgical approach. Limited literature exists comparing APC with other biomaterials for ARP, resulting in inconclusive data. APC application for ARP is a promising strategy to improve soft and hard tissue healing and reduce post-extraction pain.

Correction of osteopetrosis in the neonate oc/oc murine model after lentiviral vector gene therapy and non-genotoxic conditioning.

Autosomal recessive osteopetrosis (ARO) is a rare genetic disease, characterized by increased bone density due to defective osteoclast function. Most of the cases are due to TCIRG1 gene mutation, leading to severe bone phenotype and death in the first years of life. The standard therapy is the hematopoietic stem cell transplantation (HSCT), but its success is limited by several constraints. Conversely, gene therapy (GT) could minimize the immune-mediated complications of allogeneic HSCT and offer a prompt treatment to these patients. The Tcirg1-defective oc/oc mouse model displays a short lifespan and high bone density, closely mirroring the human condition. In this work, we exploited the oc/oc neonate mice to optimize the critical steps for a successful therapy. First, we showed that lentiviral vector GT can revert the osteopetrotic bone phenotype, allowing long-term survival and reducing extramedullary haematopoiesis. Then, we demonstrated that plerixafor-induced mobilization can further increase the high number of HSPCs circulating in peripheral blood, facilitating the collection of adequate numbers of cells for therapeutic purposes. Finally, pre-transplant non-genotoxic conditioning allowed the stable engraftment of HSPCs, albeit at lower level than conventional total body irradiation, and led to long-term survival and correction of bone phenotype, in the absence of acute toxicity. These results will pave the way to the implementation of an effective GT protocol, reducing the transplant-related complication risks in the very young and severely affected ARO patients.

Risk Factors for Secondary-Inserted Orthodontic Miniscrew Stability Following Original Insertion Failure.

The objective of this study was to examine the variables that influence the stability of secondary orthodontic anchoring miniscrews after the occurrence of initial installation failure. The secondary insertion was defined as reinserted, which was inserted to the orthotopic (i.e., inserted between the roots of the original two adjacent teeth with the mesiodistal, height and insertion angle slightly altered) and ectopic (i.e., inserted between neighboring tooth roots). A total of 100 miniscrews were reinserted in 71 patients who experienced primary insertion failure. The analysis considered 15 independent variables related to systemic factors and site characteristics. The success rate and risk factors associated with reinsertion were assessed using univariate analysis (Chi-square Test for categorical variables and Mann-Whitney U test for continuous variables) and correlation analysis (Spearman correlation analysis to exclude variables that might cause interference in a multivariable model). Significant parameters from univariate analysis were then integrated into a generalized estimating equation (GEE) model. The success rate of reinsertion was 66.00% (66/100), and the cancellous bone density and the patient's age had a strong correlation with the stability of reinserted miniscrews. The study indicates that younger patients with miniscrews reinserted in areas of high cancellous bone density are more likely to experience instability. This finding warrants careful consideration by orthodontists when performing miniscrew reinsertion procedures.

Validation of dual-energy CT-based composition analysis using fresh animal tissues and composition-optimized tissue equivalent samples

Objective. Proton therapy allows for highly conformal dose deposition, but is sensitive to range uncertainties. Several approaches currently under development measure composition-dependent secondary radiation to monitor the delivered proton range in-vivo. To fully utilize these methods, an estimate of the elemental composition of the patient’s tissue is often needed. Approach. A published dual-energy computed tomography (DECT)-based composition-extraction algorithm was validated against reference compositions obtained with two independent methods. For this purpose, a set of phantoms containing either fresh porcine tissue or tissue-mimicking samples with known, realistic compositions were imaged with a CT scanner at two different energies. Then, the prompt gamma-ray (PG) signal during proton irradiation was measured with a PG detector prototype. The PG workflow used pre-calculated Monte Carlo simulations to obtain an optimized estimate of the sample’s carbon and oxygen contents. The compositions were also assessed with chemical combustion analysis (CCA), and the stopping-power ratio (SPR) was measured with a multi-layer ionization chamber. The DECT images were used to calculate SPR-, density- and elemental composition maps, and to assign voxel-wise compositions from a selection of human tissues. For a more comprehensive set of reference compositions, the original selection was extended by 135 additional tissues, corresponding to spongiosa, high-density bones and low-density tissues. Results. The root-mean-square error for the soft tissue carbon and oxygen content was 8.5 wt% and 9.5 wt% relative to the CCA result and 2.1 wt% and 10.3 wt% relative to the PG result. The phosphorous and calcium content were predicted within 0.4 wt% and 1.1 wt% of the CCA results, respectively. The largest discrepancies were encountered in samples whose composition deviated the most from tabulated compositions or that were more inhomogeneous. Significance. Overall, DECT-based composition estimations of relevant elements were in equal or better agreement with the ground truth than the established SECT-approach and could contribute to in-vivo dose verification measurements.

The relationship between intraosseous catheter tip placement, flow rates, and infusion pressures in a high bone density cadaveric swine (Sus scrofa) model.

Intraosseous (IO) infusion is a life-preserving technique when intravenous access is unobtainable. Successful IO infusion requires sufficiently high flow rates to preserve life but at low enough pressures to avoid complications. However, IO catheter tips are often misplaced, and the relative flow rates and pressures between IO catheter tips placed in medullary, trabecular, and cortical bone are not well described, which has important implications for clinical practice. We developed the Zone Theory of IO Catheter Tip Placement based on bone density and proximity to the venous central sinus and then tested the influence of catheter tip placement locations on flow rates and pressures in a cadaveric swine model. Three cross-trained participants infused 500mL of crystalloid fluid into cadaveric swine humerus and sternum (N=210 trials total) using a push‒pull method with a 60 cm3 syringe. Computed tomography scans were scored by radiologists and categorized as zone 1 (medullary space), zone 2 (trabecular bone), or zone 3 (cortical bone) catheter tip placements. Differences between zones in flow rates, mean pressures, and peak pressures were assessed using analysis of variance and analysis of covariance to account for participant and site differences at the p<0.05 threshold. Zone 1 and zone 2 placements were essentially identical in flow rates, mean pressures, and peak pressures (each p>0.05). Zone 1 and zone 2 placements were significantly higher in flow rates and lower in pressures than zone 3 placements (each p<0.05 or less). Within the limitations of an unpressurized cadaveric swine model, the present findings suggest that IO catheter tip placements need not be perfect to acquire high flow rates at low pressures, only accurate enough to avoid the dense cortical bone of zone 3. Future research using in vivo animal and human models is needed to better define the clinical impact of IO catheter placement on infusion flow rates and pressures.

A cross-sectional CBCT assessment of the relative position of one-piece titanium-zirconium mini-implants placed for mandibular overdentures using non-guided surgery.

To assess the relative position of mini-implants to retain a mandibular overdenture, according to the surgical protocol, technical and anatomical factors. Mandibular cone-beam computed tomography (CBCT) scans were analyzed for 73 patients who received four one-piece titanium-zirconium mini-implants. Drilling was performed using a 1.6 mm needle drill and a 2.2 mm Pilot Drill, according to the bone density with a surgical stent. Post-insertion CBCT images in DICOM format were analyzed using the E-Vol-DX software with BAR filters. Divergence angle between implants and between implants and the overdenture path of insertion was measured using CliniView 10.2.6 software. Divergence between implants ranged from 0° to 22.3° (mean = 4.2; SD = 3.7) in the lateral and from 0° to 26.2° (mean = 5.3; SD = 4.1) in the frontal projections (p < .001). Only 1 (0.2%) and 3 (0.7%) of the measurements were higher than 20° in the lateral and frontal views, respectively. The mean angulations between the implant and the path of insertion for the overdenture were 9.3° (SD = 7.5) and 4.0° (SD = 2.9) for the lateral and frontal views, respectively (p < .001). Regression analyses showed a significant association between the divergence of implants and the frontal view projection (p < .001), greater distance between the paired implants (p = .017), the flapped surgical protocol (p = .002), higher final insertion torque (p = .011), and deeper preparation with the needle drill (p < .001). The mini-implants were placed with low divergence angles and satisfactory parallelism. Factors including shorter distances between the implants, higher density bone, and a flapless surgical approach all contributed positively to improved parallelism of the mini-implants.

Bone Scintigraphy for Guidance of Targeted Treatment of Vertebral Compression Fractures.

Background: Vertebral compression fractures (VCFs) are prevalent in the elderly population and might be the source of back pain if they are fresh and yet unhealed. In many cases, it is a diagnostic challenge to differentiate fresh VCFs from healed united fractures, which retain similar radiographic characteristics but no longer generate pain. This information is crucial for appropriate management. The aim of this study was to evaluate the role of bone scintigraphy (BS) in identifying fresh VCFs appropriate for targeted treatment when compared to the findings of Computerized Tomography (CT). Methods: We retrospectively reviewed 190 patients with back pain suspected to stem from a recent VCF that underwent both a CT and a BS and compared the imaging patterns per vertebra. Results: The studies were concordant in the majority of cases (95.5%), diagnosing 84.4% normal vertebrae, 6.4% acute VCFs, and 4.7% chronic VCFs. However, in 37 patients, 45 occult acute VCFs were only detected on BS and not on CT. Multivariate logistic regression analysis revealed that these patients were older and had lower bone density compared to the rest of the study population. Additionally, 40 patients had acute VCFs visible on CT, but with no increased or low intensity uptake on BS. These cases were associated with a shorter time period between trauma and BS, a higher prevalence of male patients, and a higher bone density. Acute VCFs with no increased uptake or low levels of uptake were found only within the first six days of the trauma. Conclusions: BS detects radiologically occult fractures and can differentiate if a radiographically evident VCF is indeed clinically active, guiding possible treatment options. To avoid missing acute VCFs, BS should be performed six days or more after the injury.

Bone microstructural characteristics or positional changes of condyle head affect short-term condyle head resorption after orthognathic surgery

Condylar resorption occurs in some cases after orthognathic surgery, and the risk factors associated with postoperative condylar head resorption have been extensively described. Nevertheless, even in cases with a combination of risk factors, postoperative condylar resorption may not appear. This study analyzed the microstructure and three-dimensional positional change of the condylar bone via imaging in patients who have undergone bimaxillary orthognathic surgery to determine whether the microstructure or condylar position differs between patients with and without postoperative condylar resorption. Among asymptomatic patients who underwent bimaxillary surgery between April 2021 and March 2022 at our department, 17 patients were analyzed, limited to “female,” “skeletal Class II,” and “high-angle cases,” which are known risk factors for mandibular head resorption. Multidetector computed tomography was performed on these patients before and 6 months after surgery, and the bone microstructure of the condylar head and the three-dimensional positional changes of the condylar bone and the proximal bony fragments were compared with the presence of postoperative condyle resorption using the bone morphology software TRI/3D-BON. Patients with condylar bone abnormalities before surgery and those with high trabecular bone density can develop postoperative resorption if the condyle is misaligned by surgery.

Distinguishing risk of curve progression in adolescent idiopathic scoliosis with bone microarchitecture phenotyping: a 6-year longitudinal study.

Low bone mineral density and impaired bone quality have been shown to be important prognostic factors for curve progression in adolescent idiopathic scoliosis (AIS). There is no evidence-based integrative interpretation method to analyze high-resolution peripheral quantitative computed tomography (HR-pQCT) data in AIS. This study aimed to (1) utilize unsupervised machine learning to cluster bone microarchitecture phenotypes on HR-pQCT parameters in girls with AIS, (2) assess the phenotypes' risk of curve progression and progression to surgical threshold at skeletal maturity (primary cohort), and (3) investigate risk of curve progression in a separate cohort of girls with mild AIS whose curve severity did not reach bracing threshold at recruitment (secondary cohort). Patients were followed up prospectively for 6.22 ± 0.33years in the primary cohort (n = 101). Three bone microarchitecture phenotypes were clustered by fuzzy C-means at time of peripubertal peak height velocity (PHV). Phenotype 1 had normal bone characteristics. Phenotype 2 was characterized by low bone volume and high cortical bone density, and phenotype 3 had low cortical and trabecular bone density and impaired trabecular microarchitecture. The difference in bone quality among the phenotypes was significant at peripubertal PHV and continued to skeletal maturity. Phenotype 3 had significantly increased risk of curve progression to surgical threshold at skeletal maturity (odd ratio [OR] = 4.88; 95% CI, 1.03-28.63). In the secondary cohort (n = 106), both phenotype 2 (adjusted OR = 5.39; 95% CI, 1.47-22.76) and phenotype 3 (adjusted OR = 3.67; 95% CI, 1.05-14.29) had increased risk of curve progression ≥6° with mean follow-up of 3.03 ± 0.16years. In conclusion, 3 distinct bone microarchitecture phenotypes could be clustered by unsupervised machine learning on HR-pQCT-generated bone parameters at peripubertal PHV in AIS. The bone quality reflected by these phenotypes was found to have significant differentiating risk of curve progression and progression to surgical threshold at skeletal maturity in AIS.

Monte Carlo multiscale modelling of photon and proton distribution in heterogenous tissue

Enhancements in radiotherapy treatment outcomes can be realised by minimising uncertainties in dose distribution. Current treatment planning struggles to accurately calculate dose distribution in complex heterogeneous areas, thereby increasing the uncertainty associated with dose distribution. This research focuses on studying microscopic dose distribution in the temporal bone and cochlea. This study utilised an open-access DICOM format dataset for resected temporal bone and cochlea tissue, employing the FLUKA MC code to simulate potential high-dose scenarios in volume-modulated arc therapy using the FLOOD option. Simulations were conducted at 23 photon and proton energy levels, ranging from 0.055 to 5.5 MeV for photons and 37.59–124.83 MeV for protons, to calculate dose distributions. The largest proportion of the dose (48.8%) was deposited in high-density bone at photon energies between 0.055 and 0.09 MeV. Above 0.125 MeV, a notable shift in dose distribution to low-density tissues occurred, reaching a deposition of 53%. In intermediate-density soft bone, dose distribution was 26.4% at 0.07 MeV and decreased to 19.7% at 2.5 MeV, reflecting a 29% difference in dose distribution across the energy spectrum. In proton simulations, dose distribution at low energy (37.59 MeV) revealed no significant changes across low (54.86%), intermediate (19.75%), and high-density (25.39%) areas. Similar patterns were observed at high energy (124.83 MeV), with dose distributions of 54.21% in low-, 19.79% in intermediate-, and 26% in high-density areas. The simulations demonstrated that proton dose distribution was not significantly influenced by tissue heterogeneity in micro-CT data. The photoelectric effect at low energy levels contributed minimally to the dose in soft bone, favouring higher deposition in high-density bone, despite a lower weighting factor at low energies compared with high energies.

Effect of geometrical design variables on implantation configuration and fixation stiffness of titling bone anchors: A parametric finite element study

The mechanical interaction of a tilting anchor and cancellous bones of various densities was simulated using finite element modeling. The model enjoyed a sophisticated representation of the bone, as an elasto-plastic material with large deformation capability. The anchor's tilting action during implantation phase, as well as its fixation stiffness during pull-out test, were predicted by the model and a parametric study was performed to investigate the effects of the anchor's distal width and corner fillet radius, on these measures. The model predictions were validated against the results of an experimental test on ovine humerus specimens. The model could reasonably reproduce the tilting action of the anchor during the implantation phase. Comparison of the model predictions with the experimental results revealed similar trends during both the implantation and the pull-out phases, but smaller displacement magnitudes (end points: 1.4 vs. 2.1 mm and 4.6 vs. 5.2 mm, respectively). The results of the parametric study indicated substantial increase in the fixation stiffness with increasing bone density. Reducing the distal width and increasing the fillet radius improved the anchor's implantation configuration and fixation stiffness in low-density bones. For high-density bone applications, however, a larger distal width was favored for improving the fixation stiffness.

Challenges in the Surgical Orthopedic Treatment of Long Bone Fracture in a Rare Case of Pycnodysostosis

Pycnodysostosis is a rare autosomal recessive disorder caused by an inactivating mutation in cathepsin K (CTSK) and characterized by dysmorphic facial features, a short stature, acro-osteolysis, osteosclerosis with increased bone fragility, and delayed closure of cranial sutures. Although the satisfying healing potential, many issues exist in managing fractures in pycnodysostosis patients. In this paper, we report the challenges faced in managing a fracture of the femoral shaft in a 14-year-old boy coming from a low-income family. The patient was administered to the Paediatric Surgical Emergency Department of the Children's Hospital in Rabat for the management of a closed fracture of the left femur. Despite being of small stature with dysmorphic facial features, a prominent forehead, and brachydactyly, he never had a medical consultation before. The patient then underwent a surgical reduction. We attempted titanium elastic nail fixation, but metaphyseal drilling was not feasible due to the high bone density, and the narrow medullary canal eliminated this option. Therefore we opted for the palate fixation. Sclerotic bone made drilling extremely difficult. The postoperative fracture was successfully healed.

Three-dimensional finite element analysis of the biomechanical properties of different material implants for replacing missing teeth.

The purpose of this study was to analyze the biomechanical properties of implants made of different materials to replace missing teeth by using three-dimensional finite element analysis and provide a theoretic basis for clinical application. CBCT data was imported into the Mimics and 3-Matic to construct the three-dimensional finite element model of a missing tooth restored by an implant. Then, the model was imported into the Marc Mentat. Based on the variations of the implant materials(titanium, titanium-zirconia, zirconia and poly (ether-ether-ketone) (PEEK))and bone densities (high and low),a total of eight models were created. An axial load of 150N was applied to the crown of the implant to simulate the actual occlusal situation. Both the maximum values of stresses in the cortical bone and implant were observed in the Zr-low model. The maximum displacements of the implants were also within the normal range except for the PEEK models. The cancellous bone strains were mainly distributed in the apical area of the implant, and the maximum value (3225μstrain) was found in PEEK-low model. Under the premise of the same implant material, the relevant data from various indices in low-density bone models were larger than that in high-density bone models. From the biomechanical point of view, zirconia, titanium and titanium-zirconia were all acceptable implant materials for replacing missing teeth and possessed excellent mechanical properties, while the application of PEEK material needs to be further optimized and modified.

Synergistic effect of nicotine on different implant platform design in implant-assisted mandibular overdenture, 1- Year clinical and radiographic study

Background In implant therapy, peri-implant bone loss has been noticed mainly in the first year after prosthesis insertion. This bone loss can sometimes jeopardize the outcome of the treatment. Different implant platform designs are widely used in implant dentistry; however, its influence on the health of the surrounding soft tissues and marginal bone level alterations in implant-assisted overdentures particularly in smoker patients, remains inconclusive. The purpose of this study will be to evaluate the effect of nicotine on different implant platform designs in complete mandibular implant-assisted overdenture patient. Materials and methods Ten male smoker patients were selected for this study. Split mouth study design will be used in this study where, Group I represented the right side of the patients’ mandibular interforamenal region restored with platform-switched implant and Group II represented the left side of the patients’ mandibular interforamenal region restored with nonplatform swithched implants. The patients received complete mandibular assisted overdenture with O-ring attachment. Clinical and Radiographic evaluations were carried out for every patient at regular recall visits at the time of insertion, 6, and 12 months. At the end of the study, all implants of both groups were successfully osseointegrated. The data of this study were collected, tabulated, and statistically analyzed by IBM-SPSS statistics software (Independent T-test Samples). Result There were insignificant differences between both groups regarding plaque index (PI), bleeding index (BI), pocket depth (PD) and stability of the implants. Radiographically, there were significant differences in the mandibular bone density at the bone implant interface and marginal bone loss between both groups. Group I implant represented less marginal bone loss and higher bone density than Group II implants. Conclusion In smoker patient Platform-Switched dental implant is the implant of choice to control marginal bone loss around implants.