Osseointegration of Titanium Implants With Different Rough Surfaces: A Histologic and Histomorphometric Study in an Adult Minipig Model.

BACKGROUND: Many chemical and physical modifications of titanium surfaces were introduced, aiming at improving surface bioactivity, but few comparative evidence exists. OBJECTIVE: To evaluate histologically in minipigs the osseointegration of implants made of commercially pure (CP) titanium or titanium alloy, treated by different roughening procedures. MATERIAL AND METHODS: Three sandblasted acid-etched (SA) surfaces, 2 anodized (AN), and 1 double acid-etched (DAE) were compared. Surface microtopography was characterized with scanning electron microscope; surface element composition was also assessed. One implant per group was inserted in each proximal tibia of 2 minipigs. Three months after healing, block biopsies were taken for histomorphometric analysis. Implant stability quotient (ISQ) was measured at insertion and before harvesting. RESULTS: The highest amount of cortical bone-implant contact was observed around SA implants and showed positive correlation with surface roughness. The greatest increase in ISQ was observed in CP-AN implants. In the medullary region, SA implants showed the best osteogenic response, whereas inflammatory cells were found around DAE and alloy-AN implants. CONCLUSIONS: SA surfaces were more osteogenic than anodized or dual acid-etched ones, although not significantly. Surface roughness affected osseointegration.

Empty vein ablation (EVA) technique: an in-vivo animal model to assess the effects of sclerosing agent concentration and wall contact time on intima and media tunicae structure.

BACKGROUND: Sclerotherapy is a cornerstone of the treatment of chronic venous disease, despite some technical aspects (e.g., sclerosant liquid agent concentration [SLAC] and contact time between sclerosant agent and vein wall [ctSA/VW]) to maximize outcomes remain an unsolved problem and a source of debate. An innovative three-balloon catheter has been developed to allow sclerotherapy in empty vein conditions (Empty Vein Ablation technique, EVA), revolutionizing the definition of SLAC and ctSA/VW. Aim of this experimental study is to analyze EVA effects on intima and media vessel tunicae using different SLAC and ctSA/VW in an in-vivo animal model. METHODS: Two adult sheep were treated by EVA using jugular and common iliac vein axes (eight vein segments). Different SLAC (polidocanol 0.5% or 1%) and different ctSA/VW (3 or 5 minutes) were combined for testing residual circumferential intima percentage and media thickness after EVA. RESULTS: Intact circumferential residual intima after the treatment was 21.3±4.9%, 18.2±7.4%, 15.7±2.4% and 8.9±2.0% using 0.5% (3 min), 0.5% (5 min), 1% (3 min) and 1% (5 min), respectively (R2=0.945; control sample: 97.6%). Media thickness after the treatment was 121.6±35.3 µm, 110.9±7.8 µm, 96.1±30.4 µm and 79.1±34.1 µm using 0.5% (3 min), 0.5% (5 min), 1% (3 min) and 1% (5 min), respectively (R2=0.990; control sample 125.7 µm). No significant modifications were detected analyzing the adventitia in all samples. CONCLUSIONS: EVA proved to be effective in venous wall destruction even with a very low SLAC and ctSA/VW (0.5% in 3 minutes), in quite large caliber veins. Direct comparisons with foam/liquid sclerotherapy should be done to confirm therapeutic effectiveness of these results, despite EVA has provided a maximized and controlled SA/VW contact time and ratio.

Effects of a calcium phosphate coating on the osseointegration of endosseous implants in a rabbit model.

OBJECTIVES: The aim of the present study was to evaluate a Ca-P coated implant surface in a rabbit model. The Ca-P surface (test) was compared to the titanium porous oxide surface (control) in terms of bone-to-implant contact (BIC) and removal torque value. MATERIALS AND METHODS: Two hundred and sixteen dental implants were inserted in the tibia and in the femur of 36 rabbits. One hundred and eight were represented by Ca-P oxidized surface implant and other 108 were titanium porous oxide surface modified implants. Each rabbit received six implants. Animals were sacrificed after 2, 4 and 9 weeks of healing. Each group included 12 rabbits. The femoral implant and the proximal implant of the tibia of each animal were subjected to the histologic analysis and the distal implants of the tibia underwent removal torque test (RTQ). RESULTS: Histological analysis in terms of BIC and RTQ did not revealed any significant difference between the Ca-P oxidized surface and the oxidized surface at 2 and 4 weeks. At 9 weeks, the oxidized surface demonstrated better results in terms of RTQ in the tibia. CONCLUSION: In conclusion, findings from the present study suggested that the Ca-P coating had no beneficial effect in improving bonding strength at the bone-implant interface either at 2, 4 and 9 weeks.

The Impact of Nandrolone Decanoate in the Osseointegration of Dental Implants in a Rabbit Model: Histological and Micro-Radiographic Results.

Despite high rates of osseointegration in healthy patients, complex cases present an increased risk of osseointegration failure when treated with dental implants. Furthermore, if immediate loading of the implants is used, maximizing the response of the host organism would be desirable. Anabolic steroids, such as Nandrolone Decanoate (ND), are reported to have beneficial clinical effects on various bone issues such as osteoporosis and bone fractures. However, their beneficial effects in promoting osseointegration in dental implant placement have not been documented. The study aimed to examine histological changes induced by ND in experimental dental implants in rabbit models. Two dental implants were placed in the tibias of 24 adult rabbits. Rabbits were allocated to one of two groups: control group or test group. Rabbits in the latter group were given nandrolone decanoate (15 mg/kg, immediately after implant placement and after 1 week). Micro-radiographic and histological analyses were assessed to characterize the morphological changes promoted by the nandrolone decanoate use. Total bone volume and fluorescence were significantly higher in the control group after 2 weeks. Such a difference between the two groups might indicate that, initially, nandrolone lengthens the non-specific healing period characteristic of all bone surgeries. However, after the beginning of the reparative processes, the quantity of newly formed bone appears to be significantly higher, indicating a positive stimulation of the androgen molecule on bone metabolism. Based on micro-radiology and fluorescence microscopy, nandrolone decanoate influenced bone regeneration in the implant site. The anabolic steroid nandrolone decanoate affects the healing processes of the peri-implant bone and therefore has the potential to improve the outcomes of implant treatment in medically complex patients.

Surface-modified zirconia implants: tissue response in rabbits.

AIM: To evaluate the bone tissue response to zirconia implants with three different surface modifications in comparison with the oxidized titanium surface with the goal to optimize osseointegration in terms of strength and speed. MATERIALS AND METHODS: A total of 18 rabbits with 143 implants were used. One hundred and twenty-three were threaded zirconia ceramic implants with three different surface topographies and 20 modified titanium oxide implants were controls. Each rabbit received eight implants and sacrificed after 3 weeks. The removal torque test (RTQ) and histology were performed. RESULTS: Sixteen out of 18 rabbits completed the study with a total of 110 implants. No statistical significance was observed between the chemical modification implants compared with the topographically modified zirconia implant in terms of interfacial shear strength proven by the RTQ applied. No statistical significance was also observed in the bone-to-implant contact between the zirconia implants and the control oxidized implants. CONCLUSIONS: The findings suggest that additional specific chemical modifications of the topographically modified zirconia implants do not seem to enhance the bone-to-implant contact and appear not to increase the interfacial shear strength.

Time sequence of bone healing around two implant systems in minipigs: preliminary histologic results.

The aim of this study was to evaluate the early phases of bone healing around two different implant surfaces. For this purpose, four minipigs were used. Implants with rough titanium surfaces (ITI sandblasted/acid-etched and Branemark TiUnite) were placed in the maxillae of the animals and sacrifice was scheduled in such a way that healing times of 3 days, 1 week, 2 weeks, 3 weeks, 4 weeks, 5 weeks, 6 weeks, and 7 weeks were obtained. Histologic analysis revealed that a similar pattern was observed in the phases of bone healing around both types of implants between 3 days and 7 weeks. This pattern consisted of the replacement of blood clot and bone debris with a provisional connective tissue in the first few weeks and with mineralized tissue and marrow spaces later on. Both rough surfaces allowed for "contact osteogenesis" to take place. (Int J Periodontics Restorative Dent 2009;29:549-555.).

Self-closing surgical clips for use in pericallosal artery-pericallosal artery side-to-side bypass.

The authors demonstrate the feasibility of a new procedure to create intracranial interrupted microvascular anastomosis. Self-closing nitinol surgical clips were used for a pericallosal artery-pericallosal artery side-to-side bypass in a 52-year-old man harboring an unruptured large aneurysm located on the right A2 segment. The outflow artery was found to arise from the dome of the aneurysm, which was considered unsuitable for stand-alone clip ligation or coil occlusion. After bypass patency was intraoperatively confirmed using near-infrared indocyanine green videoangiography, the aneurysm and feeding artery were embolized with coils and safely occluded. Both postoperative courses were uneventful. The patient was discharged neurologically intact on the 5th postembolization day. Postprocedure angiography demonstrated no ipsilateral aneurysm filling and excellent bilateral distal outflow from the left anterior cerebral artery.

Experimental comparison of type of Tissucol dilution and composite mesh (Parietex) for laparoscopic repair of groin and abdominal hernia: observational study conducted in a university laboratory.

PURPOSE: The primary objective of this observational study was to determine the best possible dilution of fibrin glue (Tissucol) to employ for prosthesis fixing in laparoscopic treatment of abdominal wall defects and, secondly, to assess its feasibility and safety. MATERIALS AND METHODS: This study was carried out in a university experimental animal laboratory in accordance with all international laws, ethics regulations and quality criteria associated with animal experiments. The tests were carried out on two pigs, using four samples of mesh (Parietex). All meshes were fixed using two different Tissucol dilutions (standard with distilled water and that with calcium chloride). Follow-up evaluations were at 15 days after 30 days, with the latter consisting of traction tests and a biopsy for histological analysis. RESULTS: No post-operative complications were observed. The collagen-coated polyester meshes showed 0% adhesions, and reperitonealization had ensued after 15 days. We saw no shrinkage or migration of any of the meshes. Histopathological analyses confirmed a greater stability, greater tissue integration and the largest number of fibroblasts in meshes fixed with a 1/10 Tissucol dilution without calcium chloride. CONCLUSIONS: This observational study using animals showed that the 1/10 standard dilution - not that with calcium chloride - provided the best fixation and integration and prevented the formation of intraperitoneal adhesions, provided a hydrophilic collagen film-covered mesh was used.

A translational "humanised" porcine model for transcatheter mitral valve interventions: the neo inferior vena cava approach.

AIMS: Preclinical studies and translational animal models are fundamental for the development of new clinical interventions. Compared to human anatomy, pigs present a more anterior heart position in the chest which may jeopardise the imaging and testing of devices designed to be delivered to the human mitral valve. To imitate human anatomy, we developed a novel model to "humanise" a pig heart. METHODS AND RESULTS: The creation of a neo inferior vena cava with a Dacron tube grafted to the right atrium was tested for transseptal delivery of an experimental mitral annuloplasty device in 35 animals. In 15 animals with native anatomy a conventional right transfemoral access was used. Imaging guidance was achieved with intracardiac or epicardial echocardiography. In all transfemoral approaches (n=15), the delivery of the device was unsuccessful and the handling was dissimilar to a human implant. In all neo-cava approaches (n=35), the handling and manoeuvring were as expected in humans, the targets were reached as intended and all procedures but one were successful. CONCLUSIONS: A translational "humanised" animal model with the creation of a neo cava eliminates the differences between pig and human anatomy and is suitable for testing human grade devices.

Porcine adipose-derived stem cells from buccal fat pad and subcutaneous adipose tissue for future preclinical studies in oral surgery.

INTRODUCTION: Adipose-derived stem cells (ASCs) are progenitor cells used in bone tissue engineering and regenerative medicine. Despite subcutaneous adipose tissue being more abundant, the buccal fat pad (BFP) is easily accessible for dentists and maxillofacial surgeons. For this reason, considering the need for preclinical study and the swine as an optimal animal model in tissue engineering applications, we compared the features of porcine ASCs (pASCs) from both tissue-harvesting sites. METHODS: ASCs were isolated from interscapular subcutaneous adipose tissue (ScI) and buccal fat pads of six swine. Cells were characterized for their stemness and multipotent features. Moreover, their osteogenic ability when cultured on titanium disks and silicon carbide-plasma-enhanced chemical vapor-deposition fragments, and their growth in the presence of autologous and heterologous serum were also assessed. RESULTS: Independent of the harvesting site, no differences in proliferation, viability, and clonogenicity were observed among all the pASC populations. Furthermore, when induced toward osteogenic differentiation, both ScI- and BFP-pASCs showed an increase of collagen and calcified extracellular matrix (ECM) production, alkaline phosphatase activity, and osteonectin expression, indicating their ability to differentiate toward osteoblast-like cells. In addition, they differentiated toward adipocyte-like cells, and chondrogenic induced pASCs were able to increase glycosaminoglycans (GAGs) production over time. When cells were osteoinduced on synthetic biomaterials, they significantly increased the amount of calcified ECM compared with control cells; moreover, titanium showed the osteoinductive effect on pASCs, also without chemical stimuli. Finally, these cells grew nicely in 10% FBS, and no benefits were produced by substitution with swine serum. CONCLUSIONS: Swine buccal fat pad contains progenitor cells with mesenchymal features, and they also osteo-differentiate nicely in association with synthetic supports. We suggest that porcine BFP-ASCs may be applied in preclinical studies of periodontal and bone-defect regeneration.

Injectable magnesium-enriched hydroxyapatite putty in peri-implant defects: a histomorphometric analysis in pigs.

PURPOSE: The purpose of this study was to evaluate the healing of an injectable mixture of nanoparticles of magnesium-enriched hydroxyapatite (mHA) in peri-implant defects. MATERIALS AND METHODS: Thirty-two dental implants were placed in 16 tibiae of eight female Large White pigs. In each animal, four implant beds (two sites each tibia) with medial three-wall intrabony defects were prepared. Via random selection, one bone defect in each tibia was filled with injectable mHA putty (n = 16, test group), whereas the other defect was not filled (n = 16, control group). Two animals were sacrificed after 2 weeks, two after 4 weeks, two after 6 weeks, and two after 8 weeks. In all, 32 block section samples were obtained for histologic and histomorphometric analyses. RESULTS: The test group exhibited statistically significantly higher values for bone-to-implant contact (BIC) and lower amounts of connective tissue (CT) over time. The test group showed a remarkable increase in vital bone values between 6 and 8 weeks after implant placement. After 8 weeks, the injectable mHA was almost completely resorbed. CONCLUSIONS: Injectable mHA putty could be a useful and suitable bone grafting material in peri-implant defects.