Search

Abstract Background The purpose of this study was to evaluate the osseointegration of zirconia and titanium implants in the rat maxilla in specimens under systemic antiresorptive therapy. Materials and methods After 4 weeks of systematic medication administration (either zoledronic acid or alendronic acid), 54 rats received one zirconia and one titanium implants that were immediately inserted in the rat maxilla after tooth extraction. Twelve weeks after implant placement, histopathological samples were evaluated for implant osteointegration parameters. Results The bone-implant-contact (BIC) ratio revealed no significant inter-group or inter-material differences. The distance between the implant shoulder to the bone level was significantly greater around the titanium implants of the zoledronic acid group compared to the zirconia implants of the control group (p = 0.0005). On average, signs of new bone formation could be detected in all groups, although often without statistical differences. Signs of bone necrosis were only detected around the zirconia implants of the control group (p

Abstract The purpose of this rat study was to explore the feasibility of in vivo temperature thresholds affecting bone contact at the implant surface. Based on these data, thermal necrosis should be used for implant removal in the subsequent in vivo study. Rat tibiae of 48 animals at one site were randomly treated with heat or cold before implant insertion. Temperatures of 4 °C, 3 °C, 2 °C, 48 °C, 49 °C and 50 °C for a tempering time of 1 min were evaluated. Numerical simulations of the heat source-implant-bone system were carried out. Effects were assessed by histomorphometrical measurements. The results showed that the selected method of direct tempering using a tempering pin was suitable for maintaining a uniform layer around the pin. Starting at warm temperatures of 48 °C and rising to 50 °C, the BIC ratio revealed declining values and a significant difference was observed when comparing 50 °C to the control group (p = 0.03). However, there were no significant variations within the cold temperatures. This study pinpointed temperature discovered that could lead to the thermo-explantation and so that the number of samples used in future studies on temperature-induced bone necrosis can be reduced to a minimum. Significant BIC value reduction was seen at a temperature of 50 °C for 1 min.

Abstract Background The evaluation of bone remodelling and dental root resorption can be performed by histological techniques or micro-computed tomography (micro-CT). The present study aimed to evaluate the relationship between these two procedures in the context of cleft repair in a rat model. Methods The reconstructed maxillae and the orthodontically-moved first molar of 12 rats were analysed for correlations between the histological and radiological findings retrospectively. The alveolar cleft repairs were performed using bone autografts or (human) xenografts. Four weeks after the operation, the intervention of the first molar protraction was initiated and lasted for eight weeks. The newly formed bone and the root resorption lacunae were determined via histology. In the micro-CT analysis, the average change of bone mineral density (BMD), bone volume fraction (BV/TV), trabecular thickness and trabecular separation of the jaw, as well as the volume of the root resorptions were determined. The Pearson correlation coefficient was applied to study the associations between groups. Results Positive correlations were found only between the newly formed bone (histology) and BMD changes (micro-CT) in the autograft group (r = 0.812, 95% CI: 0.001 to 0.979, p = 0.05). The relationship of newly formed bone and BV/TV was similar but not statistically significant (r = 0.691, 95% CI: −0.274 to 0.963, p = 0.013). Regarding root resorption, no significant correlations were found. Conclusions Due to the lack of correlation between histological and radiological findings of bone remodelling and the development of root resorptions, both methods should be combined in this cleft model in rats for a comprehensive analysis.

Objective: Our study was a prospective in vivo study performed on an animal model to evaluate the safety and performance of a novel venous stent designed specifically for venous applications. Methods: The novel stents were implanted in the inferior vena cava of nine sheep. The stents were deployed with different distances between the closed cell rings to test for if the segments might migrate after being deployed at maximal distance. Three different total lengths were 9, 11, and 13 cm. After 1, 3, and 6 months, vascular injury, thrombus, neointima coverage, and stent migration were evaluated through computed tomography venography and histopathology. Imaging, histology, and integration data were analyzed for each group. Results: All stents were deployed successfully, and all sheep survived until the time of harvesting. In all cases, the native blood vessel sections were intact. The segmented stent parts showed a differently pronounced tissue coverage, depending on the duration of the implantation. Conclusions: The new nitinol stent is safe and feasible to implant in the venous system with a rapid surface coverage. Alteration of stent length did not affect the development of neointimal formation and did not cause migration. : Clinical Relevance: The clinical relevance of our study titled ''Evaluation of Safety and Performance of a New Prototype Self-Expandable Nitinol Stent in an Ovine Model'' lies in its potential to advance the field of venous intervention. Stent implantation is a common procedure used to treat deep venous obstruction, and the use of self-expandable nitinol stents has been shown to be effective in improving the patency rates. However, the safety and efficacy of new stent prototypes must be evaluated thoroughly before they can be used in clinical practice. Our study contributes to the evaluation of a new prototype self-expandable nitinol stent by demonstrating its excellent mechanical properties, biocompatibility, and histopathological response in an ovine model. The results of our study may provide valuable insight for researchers and clinicians in developing and implementing new stent technologies, ultimately improving patient outcomes in the treatment of chronic venous obstruction.

Abstract To minimize the postoperative risks posed by grafting autologous transplants for cleft repair, efforts are being made to improve grafting materials for use as potential alternatives. The aim of this study was to compare the bone graft quality of different bone substitutes including the gold standard autografts during the healing processes after cleft repair in the context of orthodontic treatment. In 21 Wistar rats, a complete, continuity-interrupting cleft was created. After 4 weeks, cleft repair was performed using autografts from the hips’ ischial tuberosity, human xenografts, or synthetic bone substitutes [beta-tricalcium phosphate (β-TCP)/hydroxyapatite (HA)]. After another 4 weeks, the first molar movement was initiated in the reconstructed jaw for 8 weeks. The bone remodeling was analyzed in vivo using micro-computed tomography (bone mineral density and bone volume fraction) and histology (new bone formation). All the grafting materials were statistically different in bone morphology, which changed during the treatment period. The β-TCP/HA substitute demonstrated less resorption compared to the autologous and xenogeneic/human bone, and the autografts led to a stronger reaction in the surrounding bone. Histologically, the highest level of new bone formation was found in the human xenografts, and the lowest was found in the β-TCP/HA substitute. The differences between the two bone groups and the synthetic materials were statistically significant. Autografts were confirmed to be the gold standard in cleft repair with regard to graft integration. However, parts of the human xenograft seemed comparable to the autografts. Thus, this substitute could perhaps be used as an alternative after additional tissue-engineered modification.

Abstract Superparamagnetic iron oxide nanoparticles (SPION) are extensively used for magnetic resonance imaging (MRI) and magnetic particle imaging (MPI), as well as for magnetic fluid hyperthermia (MFH). We here describe a sequential centrifugation protocol to obtain SPION with well-defined sizes from a polydisperse SPION starting formulation, synthesized using the routinely employed co-precipitation technique. Transmission electron microscopy, dynamic light scattering and nanoparticle tracking analyses show that the SPION fractions obtained upon size-isolation are well-defined and almost monodisperse. MRI, MPI and MFH analyses demonstrate improved imaging and hyperthermia performance for size-isolated SPION as compared to the polydisperse starting mixture, as well as to commercial and clinically used iron oxide nanoparticle formulations, such as Resovist® and Sinerem®. The size-isolation protocol presented here may help to identify SPION with optimal properties for diagnostic, therapeutic and theranostic applications.

Nontraumatic osteonecrosis of the femoral head is still a challenging problem in orthopedic surgery. It is responsible for 10% of the 500,000 hip replacement surgeries in the USA and affects relatively young, active patients in particular. Main reasons for nontraumatic osteonecrosis are glucocorticoid use, alcoholism, thrombophilia, and hypofibrinolysis (Glueck et al., 1997; Orth and Anagnostakos, 2013). One pathomechanism of steroid-induced osteonecrosis is thought to be impaired blood flow to the femoral head caused by increased thrombus formation and vasoconstriction. To investigate the preventive effect of enoxaparin on steroid-related osteonecrosis, we used male New Zealand white rabbits. Osteonecrosis was induced by methylprednisolone-injection (1×20 mg/kg body weight). Control animals were treated with phosphate-buffered saline. Treatment consisted of an injection of 11.7 mg/kg body weight of enoxaparin per day (Clexane) in addition to methylprednisolone. Four weeks after methylprednisolone-injection the animals were sacrificed. Histology (hematoxylin-eosin and Ladewig staining) was performed, and empty lacunae and histological signs of osteonecrosis were quantified. Histomorphometry revealed a significant increase in empty lacunae and necrotic changed osteocytes in glucocorticoid-treated animals as compared with the glucocorticoid- and Clexane-treated animals and with the control group. No significant difference was detected between the glucocorticoid and Clexane group and the control group. This finding suggests that cotreatment with enoxaparin has the potential to prevent steroid-associated osteonecrosis.