Current Issue : April - June Volume : 2015 Issue Number : 2 Articles : 8 Articles
Purpose. To investigate in vivo the acute host response to an alternative implant designed for the treatment of stress urinary\nincontinence (SUI) and pelvic organ prolapse (POP). Methods. A biodegradable scaffold was produced from poly-L-lactic acid\n(PLA) using the electro spinning technique. Human and rat adipose-derived stem cells (ADSCs) were isolated and characterized by\nfluorescence-activated cell sorting and differentiation assays. PLA scaffolds were seeded and cultured for 2 weeks with human or rat\nADSCs. Scaffolds with and without human or rat ADSCs were implanted subcutaneously on the abdominal wall of rats. After 3 and\n7 days, 6 animals from each group were sacrificed. Sections from each sample were analyzed by Haematoxylin and Eosin staining,\nSirius red staining, and immunohistochemistry for CD68, PECAM-1, and collagen I and III. Results. Animals responded to the\nscaffolds with an acute macro phage response. After 7 days of implantation, there was extensive host cell penetration, new blood\nvessel formation, and new collagen deposition throughout the full thickness of the samples without obvious differences between\ncell-containing and cell-free scaffolds. Conclusions. The acute in vivo response to an alternative implant (both with and without\ncells) for the treatment of SUI and POP showed good acute integration into the host tissues....
Thepresent study aims to evaluate the influence of apicocoronal position and immediate and conventional loading in the percentage\nof bone-implant contact (BIC). Thus, 36 implants were inserted in the edentulous mandible from six dogs. Three implants were\ninstalled in each hemimandible, in different positions in relation to the ridge: Bone Level (at crestal bone level), Minus 1 (one\nmillimeter apical to crestal bone), and Minus 2 (two millimeters apical to crestal bone). In addition, each hemimandible was\nsubmitted to a loading protocol: immediate (prosthesis installed 24 hours after implantation) or conventional (prosthesis installed\n120 days after implantation). Ninety days after, animals were killed, and implant and adjacent tissues were prepared for histometric\nanalysis. BICvalues fromimmediate loaded implantswere 58.7%, 57.7%, and 51.1%, respectively,while conventional loaded implants\nwere 61.8%, 53.8%, and 68.4%. Differences statistically significant were not observed among groups (P = 0.10, ANOVA test). These\nfindings suggest that different apicocoronal positioning and loading protocols evaluated did not interfere in the percentage of boneimplant\ncontact, suggesting that these procedures did not jeopardize osseointegration....
The objective of our study was to determine the mechanical stress conditions under tibiofemoral loading with an overlay of knee\nkinematics in deep flexion on two different mobile bearing designs in comparison to in vivo failure modes. This study investigates\nthe seldombut severe complication of fatigue failure of polyethylene components atmobile bearing total knee arthroplasty designs.\nAssuming a combination of a floor-based lifestyle and tibial malrotation as a possible reason for a higher failure rate in Asian\ncountrieswe developed a simplified finite elementmodel considering a tibiofemoral roll-back angle of 22? and the range of rotational\nmotion of a clinically established floating platform design (e.motion FP) at a knee flexion angle of 120? in order to compare our\nresults to failure modes found in retrieved implants. Compared to the failure mode observed in the clinical retrievals the locations\nof the occurring stress maxima as well as the tensile stress distribution show analogies. Fromour observations, we conclude that the\nnewly introduced finite element model with an overlay of deep knee flexion (lateral roll-back) and considerable internally rotated\ntibia implant positioning is an appropriate analysis for knee design optimizations and a suitable method to predict clinical failure\nmodes....
Objective.Thestudy was to investigate the impact of orthotropic material on the biomechanics of dental implant, based on a detailed\nmandible with high geometric and mechanical similarity. Materials and Methods. Multiple data sources were used to elaborate\ndetailed biological structures and implant CAD models. In addition, an extended orthotropic material assignment methodology\nbased on harmonic fields was used to handle the alveolar ridge region to generate compatible orthotropic fields. The influence\nof orthotropic material was compared with the commonly used isotropic model and simplified orthotropic model. Results. The\nsimulation results showed that the values of stress and strain on the implant-bone interface almost increased in the orthotropic\nmodel compared to the isotropic case, especially for the cancellous bone. However, the local stress concentration was more obvious\nin the isotropic case compared to that in orthotropic case. The simple orthotropic model revealed irregular stress and strain\ndistribution, compared to the isotropicmodel and the real orthotropicmodel.The influence of orthotropy was little on the implant,\nperiodontal ligament, tooth enamel, and dentin. Conclusion. The orthotropic material has significant effect on stress and strain\nof implant-bone interface in the mandible, compared with the isotropic simulation. Real orthotropic mechanical properties of\nmandible should be emphasized in biomechanical studies of dental implants...
The aim of this study was to investigate the efficacy of a proposed new implant mediated drug delivery system (IMDDS) in rabbits.\nThe drug delivery system is applied through a modified titanium implant that is configured to be implanted into bone. The implant\nis hollow and has multiple microholes that can continuously deliver therapeutic agents into the systematic body. To examine the\nefficacy and feasibility of the IMDDS, we investigated the pharmacokinetic behavior of dexamethasone in plasma after a single dose\nwas delivered via the modified implant placed in the rabbit tibia. After measuring the plasma concentration, the areas under the\ncurve showed that the IMDDS provided a sustained release for a relatively long period. The result suggests that the IMDDS can\ndeliver a sustained release of certain drug components with a high bioavailability. Accordingly, the IMDDS may provide the basis\nfor a novel approach to treating patients with chronic diseases....
Objective. To compare hearing and speech understanding between a new, nonskin penetrating Baha system (Baha Attract) to\nthe current Baha system using a skin-penetrating abutment. Methods. Hearing and speech understanding were measured in 16\nexperienced Baha users. The transmission path via the abutment was compared to a simulated Baha Attract transmission path by\nattaching the implantable magnet to the abutment and then by adding a sample of artificial skin and the external parts of the Baha\nAttract system. Four different measurements were performed: bone conduction thresholds directly through the sound processor\n(BC Direct), aided sound field thresholds, aided speech understanding in quiet, and aided speech understanding in noise. Results.\nThesimulated Baha Attract transmission path introduced an attenuation starting fromapproximately 5 dB at 1000Hz, increasing to\n20ââ?¬â??25 dB above 6000Hz. However, aided sound field threshold shows smaller differences and aided speech understanding in quiet\nand in noise does not differ significantly between the two transmission paths. Conclusion. The Baha Attract system transmission\npath introduces predominately high frequency attenuation. This attenuation can be partially compensated by adequate fitting of\nthe speech processor. No significant decrease in speech understanding in either quiet or in noise was found....
Objectives. The goal of this study was to evaluate bone changes around endosseous implants in partially edentulous patients.\nMaterials and Methods. A total of 632 two-stage implants were placed in 252 patients. The implants had straight emergence profile,\nZirTi surface, 3.3 to 5mm diameter, and 8.5 to 13mm length. Bone levels were assessed on orthopantomography immediately after\nsurgery and after 36 months and marginal bone loss (MBL) was calculated from their difference. Results. Cumulative survival rate\nwas 98.73%. Overall MBL was 0.8mm Ã?± 0.03 (mean Ã?± SEM). Higher MBL was observed around implants in the maxilla than in\nthe mandible (???? < 0.007). A relation between implant diameter and MBL (P < 0.0001) was observed in male and, more limitedly,\nfemale patients. Older patients had higher MBL in the maxilla, but not in the mandible (P < 0.0001). MBL progressively increased\nwith age in male patients, but reached a peak already in the 50ââ?¬â??60 years age group in the female subset (P < 0.001). Conclusions.\nThe overall MBL is consistent with the available literature. Site difference and patient age and gender appear to significantly affect\nMBL, representing important factors to be considered during implant placement....
Background. Wear-related failures and instabilities are frequent failure mechanisms of total knee replacements. High-conforming\ndesigns may provide additional stability for the joint. This study analyzes the effects of a ligamentous insufficiency on the stability\nand the wear behavior of a high-conforming knee design. Methods. Two simulator wear tests were performed on a high-conforming\ntotal knee replacement design. In the first, a ligamentous-stable knee replacement with a sacrificed anterior cruciate ligament\nwas simulated. In the second, a ligamentous-unstable knee with additionally insufficient posterior cruciate ligament and medial\ncollateral ligament was simulated. Wear was determined gravimetrically and wear particles were analyzed. Implant kinematics\nwas recorded during simulation. Results. Significantly higher wear rates (P ? 0.001) were observed for the unstable knee\n(14.58 �± 0.56mg/106 cycles) compared to the stable knee (7.97 �± 0.87mg/106 cycles). A higher number of wear particles with only\nsmall differences in wear particle characteristics were observed. Under unstable knee conditions, kinematics increased significantly\nfor translations and rotations (P ? 0.01). This increase was mainly attributed to higher tibial posterior translation and internal\nrotations. Conclusion. Higher kinematics under unstable test conditions is a result of insufficient stabilization via implant design.\nDue to the higher kinematics, increased wear was observed in this study....
Loading....