Current Issue : July - September Volume : 2015 Issue Number : 3 Articles : 8 Articles
To systematically measure and compare the stress distribution on the bone around an implant in the anterior maxilla using angled\nabutments by means of finite element analysis, three-dimensional finite element simplified patient-specific models and simplified\nmodels were created and analyzed. Systematically varied angled abutments were simulated, with angulation ranging from0? to 60?.\nThe materials in the current study were assumed to be homogenous, linearly elastic, and isotropic. Force of 100N was applied to\nthe central node on the top surface of the abutments to simulate the occlusal force. To simulate axial and oblique loading, the angle\nof loading was 0?, 15?, and 20? to the long axis of implant, respectively. There was the strong resemblance between the response\ncurves for simplified patient-specific models and simplified models. Response curves under oblique loading were similar in both\nmodels.With abutments angulation increased, maximum vonMises stress firstly decreased to minimum point and then gradually\nincreased to higher level. From a biomechanical point of view, favorable peri-implant stress levels could be induced by angled\nabutments under oblique loading if suitable angulation of abutments was selected....
Ceramic materials are widely used for biomedical applications because of their remarkable biological and mechanical properties.\nComposites made of alumina and zirconia are particularly interesting owing to their higher toughness with respect to themonolithic\nmaterials. On this basis, the present study is focused on the in vivo behavior of alumina toughened zirconia (ATZ) dental implants\ntreated with a hydrothermal process. A minipig model was implemented to assess the bone healing through histology and mRNA\nexpression at different time points (8, 14, 28, and 56 days). The novel ATZ implant was compared to a titanium clinical standard.\nThe implants were analyzed in terms of microstructure and surface roughness before in vivo tests. The most interesting result deals\nwith a statistically significant higher digital histology index for ATZ implants with respect to titanium standard at 56 days, which\nis an unprecedented finding, to the authors� knowledge. Even if further investigations are needed before proposing the clinical use\nin humans, the tested material proved to be a promising candidate among the possible ceramic dental implants....
Radiotherapy may compromise the integration of implant and cause implant loss. Implant surface modifications have the possibility\nof promoting cell attachment, cell growth, and bone formation which ultimately enhance the osseointegration process. The present\nstudy aimed to investigate the effects of calcium phosphate nanocrystals on implant osseointegration in irradiated bone. Sixteen\nrabbits were randomly assigned into control and nano-CaP groups, receiving implants with dual acid-etched surface or dual acidetched\nsurface discretely deposited of nanoscale calcium-phosphate crystals, respectively. The left leg of all the rabbits received\n15Gy radiation, followed by implants placement one week after. Four animals in each group were sacrificed after 4 and 12 weeks,\nrespectively. Implant stability quotient (ISQ), ratio of bone volume to total volume (BV/TV), bone growth rate, and bone-to-implant\ncontact (BIC) were evaluated. The nano-CaP group showed significantly higher ISQ (week 12, P = 0.031) and bone growth rate\n(week 6, P = 0.021; week 9, P = 0.001) than that in control group. No significant differences in BV/TV and BIC were found\nbetween two groups. Titanium implant surface modified with CaP nanocrystals provides a potential alternative to improve bone\nhealing around implant in irradiated bone....
The aim of this paper is to describe a case of implant-prosthetic rehabilitation in a patient with periodontitis, focusing on the\ndifferent timing of implant placement. After initial periodontal treatment, teeth with advanced mobility degree and severe bone\nresorptionwere extracted.At different healing time oral implantswere placed in a prosthetic-guided position.After osseointegration\nperiod the implants were loaded and the results at one year of follow-up are presented....
Nimodipine is a widely used medication for treating delayed cerebral ischemia (DCI) after subarachnoid hemorrhage. When\nadministrated orally or intravenously, systemic hypotension is an undesirable side effect. Intracranial subarachnoid delivery of\nnimodipine during aneurysm clipping may bemore efficient way of preventing vasospasm and DCI due to higher concentration of\nnimodipine in cerebrospinal fluid (CSF).Therisk of systemic hypotension may also be decreasedwith intracranial delivery.We used\nanimal models to evaluate the feasibility of surgically implanting a silica-based nimodipine releasing implant into the subarachnoid\nspace through a frontotemporal craniotomy. Concentrations of released nimodipine were measured fromplasma samples and CSF\nsamples. Implant degradation was followed using CT imaging. After completing the recovery period, full histological examination\nwas performed on the brain and meninges. The in vitro characteristics of the implant were determined. Our results show that the\nbiodegradable silica-based implant can be used for an intracranial drug delivery systemand nomajor histopathological foreign body\nreactions were observed. CT imaging is a feasible method for determining the degradation of silica implants in vivo.The sustained\nrelease profiles of nimodipine in CSF were achieved. Compared to a traditional treatment, higher nimodipine CSF/plasma ratios\ncan be obtained with the implant....
The peripheral giant cell granuloma (PGCG) is a nonneoplastic lesion commonly caused by local irritation. This report describes\na 46-year-old Caucasian male who presented with a PGCG associated with a dental implant. The dental implant was originally\nplaced in August 2012. Ten months later, the patient presented with a well-circumscribed lesion associated with and covering the\nimplant, at which time the lesion was excised. Four months later, due to recurrence of the lesion, a deeper and wider excisional\nbiopsy with curettage of the adjacent bone was performed. No evidence of recurrence has been reported after 12 months of followup.\nImmunohistochemistry, using the antibody CD68, was performed to investigate the origin of the multinucleated giant cells,\nwith their immunophenotype being similar to those of other giant cell lesions, including central giant cell granuloma, foreign-body\nreactions, and granulomatous reactions to infectious agents....
Retropatellar complications after total knee arthroplasty (TKA) such as anterior knee pain and subluxations might be related\nto altered patellofemoral biomechanics, in particular to trochlear design and femorotibial joint positioning. A method was\ndeveloped to test femorotibial and patellofemoral joint modifications separately with 3D-rapid prototyped components for in\nvitro tests, but material differences may further influence results. This pilot study aims at validating the use of prostheses made\nof photopolymerized rapid prototype material (RPM) by measuring the sliding friction with a ring-on-disc setup as well as knee\nkinematics and retropatellar pressure on a knee rig. Cobalt-chromium alloy (standard prosthesis material, SPM) prostheses served\nas validation standard. Friction coefficients between these materials and polytetrafluoroethylene (PTFE) were additionally tested\nas this latter material is commonly used to protect pressure sensors in experiments. No statistical differences were found between\nfriction coefficients of both materials to PTFE. UHMWPE shows higher friction coefficient at low axial loads for RPM, a difference\nthat disappears at higher load. No measurable statistical differences were found in knee kinematics and retropatellar pressure\ndistribution. This suggests that using polymer prototypes may be a valid alternative to original components for in vitro TKA studies\nand future investigations on knee biomechanics....
With the development of nanotechnology, many researches have shown that nanometer-scaled materials especially TiO2 nanotube\nhave a positive effect on cellular behavior and surface characteristics of implant, which are considered to be crucial factors in\nosseointegration. However, it has not yet been verified which nanotube size is effective in osseointegration in vivo. The aimof this\nstudy was to evaluate the effect of implant surface-treated with different size of TiO2 nanotubes on osseointegration in rat femur.The\ncustomized implants (threaded and non threaded type), surface-treated with different diameter of TiO2 nanotubes (30 nm, 50 nm,\n70 nm, and 100nm nanotube), were placed on both sides of the femur of 50 male Sprague-Dawley rats (6 weeks old). Rats were\nsacrificed at 2 and 6 weeks following surgery; then the specimens were collected by perfusion fixation and the osseointegration of\nimplants was evaluated by radiographic and histologic analyses and removal torque value test. The mean of bone area (%) and the\nmean of removal torque were different in each group, indicating that the difference in TiO2 nanotube size may influence new bone\nformation and osseointegration in rats....
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