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Implant Design (implant + design)
Selected AbstractsEffects of Implant Design and Surface on Bone Regeneration and Implant Stability: An Experimental Study in the Dog MandibleCLINICAL IMPLANT DENTISTRY AND RELATED RESEARCH, Issue 1 2001Lars Rasmusson DMD ABSTRACT Background: Previous experimental studies have shown a higher degree of bone-implant contact for surface-enlarged implants compared with machined implants. Yet, there is insufficient evidence that such implants show higher stability and an increased survival rate. Purpose: The purpose of this investigation was to study the integration and stability of grit-blasted implants with retention elements on the implant neck, with and without marginal bone defects, compared with machined implants without retention elements. Materials and Methods: After tooth extraction of the mandibular premolars in six dogs, two grit-blasted, partly microthreaded Astra Tech implants and one standard Branemark implant were bilaterally placed in each dog. On one side, 3 ± 3 mm large buccal defects were created, to expose three to four implant threads. The contralateral side served as control, and no defects were made. The animals were sacrificed after 4 months of healing. Implant stability was measured using resonance frequency analysis at implant installation and after 4 months of healing. Histologic and histomorpho-metric evaluation was made after 4 months of healing. Results: Resonance frequency analysis indicated that all implants in the test and control groups were osseointegrated after 4 months, with a tendency toward higher implant stability for the Astra Tech implants. There was a statistically significant higher increase in resonance frequency for the Astra test implants compared with their corresponding controls. Histology and histomorphometry showed well-integrated implants with varying degrees of bone repair at the defect sites. The greater bone-implant contact for the Astra implants was statistically significant. No significant difference between the implants in amount of bone filling the threads was recorded. Conclusions: The Astra Tech implants tested showed a higher degree of bone,implant contact and higher level of bone regenerated at defect sites compared with the Brånemark implants. Resonance frequency analysis demonstrated a significantly higher increase in the Astra test implants compared with their control groups than did the Brånemark test implants versus their controls. [source] Fibronectin Functionalized Hydroxyapatite Coatings: Improving Dermal Fibroblast Adhesion In Vitro and In Vivo,ADVANCED ENGINEERING MATERIALS, Issue 8 2010Catherine J. Pendegrass Skin-penetrating devices including intraosseous transcutaneous amputation prostheses (ITAP) and external fixator pins rely on a skin-implant seal to prevent infection. In this study, we assess the effectiveness of fibronectin (Fn) functionalized hydroxyapatite (HA) coatings for promoting dermal fibroblast and dermal tissue attachment and ingrowth in vitro and in vivo. By measuring the number of focal adhesions per unit cell area we have demonstrated that HA significantly promotes dermal fibroblast attachment compared with titanium alloy. Dermal fibroblast attachment is promoted further using Fn functionalized HA coatings incorporated into an implant design with 700,µm pores, which significantly increased dermal tissue ingrowth and attachment compared with non-functionalized HA and titanium alloy controls incorporating 500 or 1000,µm pores. We postulate that Fn functionalized HA coatings applied to transdermal implants may promote and sustain the skin-implant interface and assist in preventing infection long term. [source] Functional behaviour of bone around dental implants,GERODONTOLOGY, Issue 2 2004Clark M. Stanford Achieving a long-term stable implant interface is a significant clinical issue when there is insufficient cortical bone stabilisation at implant placement. Clinical outcomes studies suggest that the higher risk implants are those placed in compromised cortical bone (thin, porous, etc.) in anatomical sites with minimal existing trabecular bone (characterised as type IV bone). In establishing and maintaining an implant interface in such an environment, one needs to consider the impact of masticatory forces, the response of bone to these forces and the impact of age on the adaptive capacity of bone. These forces, in turn, have the potential to create localised changes in interfacial stiffness through viscoelastic changes at the interface. Changes in bone as a function of age (e.g. localised hypermineralised osteopetrosis and localised areas of osteopenia) will alter the communication between osteocytes and osteoblasts creating the potential for differences in response of osteoblastic cells in the older population. A key to understanding the biomechanical and functional behaviour of implants in the older population is to control the anticipated modelling and remodelling behaviour through implant design that takes into account how tissues respond to the mechanically active environment. [source] The effect of nucleus implant parameters on the compressive mechanics of the lumbar intervertebral disc: A finite element studyJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2009Abhijeet Joshi Abstract A simplified finite element model of the human lumbar intervertebral disc was utilized for understanding nucleus pulposus implant mechanics. The model was used to assess the effect of nucleus implant parameter variations on the resulting compressive biomechanics of the lumbar anterior column unit. The effects of nucleus implant material (modulus and Poisson's ratio) and geometrical (height and diameter) parameters on the mechanical behavior of the disc were investigated. The model predicted that variations in implant modulus contribute less to the compressive disc mechanics compared to the implant geometrical parameters, for the ranges examined. It was concluded that some threshold exists for the nucleus implant modulus, below which little variations in load,displacement behavior were shown. Compressive biomechanics were highly affected by implant volume (under-filling the nucleus cavity, line-to-line fit, or over-filling the nucleus cavity) with a greater restoration of compressive mechanics observed with the over-filled implant design. This work indicated the effect of nucleus implant parameter variations on the compressive mechanics of the human lumbar intervertebral disc and importance of the "fit and fill" effect of the nuclear cavity in the restoration of the human intervertebral disc mechanics in compression. These findings may have clinical significance for nucleus implant design. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009 [source] Influence of controlled immediate loading and implant design on peri-implant bone formationJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 2 2007Katleen Vandamme Abstract Aim: Tissue formation at the implant interface is known to be sensitive to mechanical stimuli. The aim of the study was to compare the bone formation around immediately loaded versus unloaded implants in two different implant macro-designs. Material and Methods: A repeated sampling bone chamber with a central implant was installed in the tibia of 10 rabbits. Highly controlled loading experiments were designed for a cylindrical (CL) and screw-shaped (SL) implant, while the unloaded screw-shaped (SU) implant served as a control. An F -statistic model with ,=5% determined statistical significance. Results: A significantly higher bone area fraction was observed for SL compared with SU (p<0.0001). The mineralized bone fraction was the highest for SL and significantly different from SU (p<0.0001). The chance that osteoid- and bone-to-implant contact occurred was the highest for SL and significantly different from SU (p<0.0001), but not from CL. When bone-to-implant contact was observed, a loading (SL versus SU: p=0.0049) as well as an implant geometry effect (SL versus CL: p=0.01) was found, in favour of the SL condition. Conclusions: Well-controlled immediate implant loading accelerates tissue mineralization at the interface. Adequate bone stimulation via mechanical coupling may account for the larger bone response around the screw-type implant compared with the cylindrical implant. [source] Electrophysiologic Effects of Placing Cochlear Implant Electrodes in a Perimodiolar Position in Young Children,THE LARYNGOSCOPE, Issue 1 2004Phillip A. Wackym MD Abstract Objective The purpose of this study was to intraoperatively record the electrically evoked auditory brainstem response (EABR) before and after placement of the electrode positioning system (EPS) (CII Bionic Ear with HiFocus I cochlear implant electrode array) as well as before and after stylet removal (Nucleus Contour cochlear implant electrode array). It was hypothesized that physiologic changes would occur after perimodiolar positioning of the electrode array and these changes would be evident from the EABR recordings. Study Design Consecutive young (11,36 month old) pediatric cochlear implant recipients (n = 17) had intraoperative EABRs recorded from three intracochlear electrodes that represented apical, medial, and basal locations. Wave V amplitudes and thresholds were studied relative to electrode location and pre- versus postperimodiolar positioning. These evoked potential measures were analyzed for statistical significance. Setting Tertiary referral children's hospital/medical college. Results Wave V thresholds of the EABR were lower, and amplitudes were larger after perimodiolar positioning, although the changes were dependent on electrode location and implant design. Statistically significant decreases in EABR wave V threshold and increases in suprathreshold wave V amplitude were found for the basal electrode for the CII Bionic Ear HiFocus I and for the apical electrode for the Nucleus Contour. Conclusions Placement of either the CII Bionic Ear HiFocus I or Nucleus Contour cochlear implant electrode array in the perimodiolar position in young children resulted in less electrical current necessary to stimulate the auditory system. Changes in electrophysiologic thresholds and amplitudes, measured with EABR, indicate that the electrode array is placed closer to the modiolus with both electrode designs. [source] Probing vocal fold fibroblast response to hyaluronan in 3D contexts,BIOTECHNOLOGY & BIOENGINEERING, Issue 4 2009Dany J. Munoz-Pinto Abstract A number of treatments are being investigated for vocal fold (VF) scar, including designer implants. The aim of the present study was to validate a 3D model system for probing the effects of various bioactive moieties on VF fibroblast (VFF) behavior toward rational implant design. We selected poly(ethylene glycol) diacrylate (PEGDA) hydrogels as our base-scaffold due to their broadly tunable material properties. However, since cells encapsulated in PEGDA hydrogels are generally forced to take on rounded/stellate morphologies, validation of PEGDA gels as a 3D VFF model system required that the present work directly parallel previous studies involving more permissive scaffolds. We therefore chose to focus on hyaluronan (HA), a polysaccharide that has been a particular focus of the VF community. Toward this end, porcine VFFs were encapsulated in PEGDA hydrogels containing consistent levels of high Mw HA (${\rm HA}_{{\rm H}{M}_{\rm W} } $), intermediate Mw HA (${\rm HA}_{{\rm I}{M}_{\rm W} } $), or the control polysaccharide, alginate, and cultured for 7 and 21 days. ${\rm HA}_{{\rm H}{M}_{\rm W} } $ promoted sustained increases in active ERK1/2 relative to ${\rm HA}_{{\rm I}{M}_{\rm W} } $ . Furthermore, VFFs in ${\rm HA}_{{\rm I}{M}_{\rm W} } $ gels displayed a more myofibroblast-like phenotype, higher elastin production, and greater protein kinase C (PkC) levels at day 21 than VFFs in ${\rm HA}_{{\rm H}{M}_{\rm W} } $ and alginate gels. The present results are in agreement with a previous 3D study of VFF responses to ${\rm HA}_{{\rm I}{M}_{\rm W} } $ relative to alginate in collagen-based scaffolds permissive of cell elongation, indicating that PEGDA hydrogels may serve as an effective 3D model system for probing at least certain aspects of VFF behavior. Biotechnol. Bioeng. 2009; 104: 821,831 © 2009 Wiley Periodicals, Inc. [source] Parameters for Successful Implant Integration Revisited Part I: Immediate Loading Considered in Light of the Original Prerequisites for OsseointegrationCLINICAL IMPLANT DENTISTRY AND RELATED RESEARCH, Issue 2010FACD, Oded Bahat BDS ABSTRACT Purpose: With the increasing popularity and publication of loading implants at the time of placement, including at time of dental extraction and simultaneous with reconstructive procedures, the objective was to evaluate known variables identified for a traditional unloaded healing period and determine the applicability of these variables to immediate loading. Materials: A total of 124 published reports available as of January 2008 that contained information about loading from the time of surgery up to 3 months postsurgically were examined in light of published variables affecting osseointegration based on a 2 stage surgical approach. Methods: The articles were examined to differentiate between immediate loading (within the initial 48 hours) and early/delayed loading of implants. Success or survival criteria were noted, and where reasons for failure were available, categorized according to six variables considered as determinants for maintaining a long-term bone-to-implant contact. Results: Approximately 60 of the 124 reports described immediately loading implants within 48 with single-tooth, partial, and full-arch restorations, as well as implant overdentures. The implant success or survival rates ranged from 70.8% to 100%. Most studies considered implant survival to be the only criterion for success. Conclusions: Of six parameters identified in 1981 as influencing osseointegration, two parameters (the status of the bone/implant site and implant loading conditions) appear to have diagnostic implications, whereas three (implant design, surgical technique, and implant finish) may affect immediate loading positively or adversely. [source] Parameters for Successful Implant Integration Revisited Part II: Algorithm for Immediate Loading Diagnostic FactorsCLINICAL IMPLANT DENTISTRY AND RELATED RESEARCH, Issue 2010FACD, Oded Bahat BDS ABSTRACT Immediate loading of dental implants has become a widely reported practice with success rates ranging from 70.8% to 100%. Although most studies have considered implant survival to be the only measure of success, a better definition includes the long-term stability of the hard and soft tissues around the implant(s) and other adjacent structures, as well as the long-term stability of all the restorative components. The parameters identified in 1981 by Albrektsson and colleagues as influencing the establishment and maintenance of osseointegration have been reconsidered in relation to immediate loading to improve the chances of achieving such success. Two of the six parameters (status of the bone/implant site and implant loading conditions) have preoperative diagnostic implications, whereas three (implant design, surgical technique, and implant finish) may compensate for less-than-ideal site and loading conditions. Factors affecting the outcome of immediate loading are reviewed to assist clinicians attempting to assess its risks and benefits. [source] Direct loading of Nobel Direct® and Nobel Perfect® one-piece implants: a 1-year prospective clinical and radiographic studyCLINICAL ORAL IMPLANTS RESEARCH, Issue 4 2007Per-Olov Östman Abstract Objectives: The aim of this prospective study was to evaluate the Nobel Direct® and Nobel Perfect® one-piece implants (OPIs) when used for immediate function. Material and methods: Forty-eight patients were provided with 115 OPIs for loading with a provisional crown or a bridge within 24 h and followed for at least 12 months with clinical and radiographic examinations. A group of 97 patients previously treated under identical conditions by the same team with 380 two-piece implants (TPIs) for immediate loading in the mandible and maxilla served as the reference group. Results: Six (5.2%) OPIs failed during the follow-up due to extensive bone loss. Five (1.3%) implants failed in the reference group. After 1 year, the mean marginal bone loss was 2.1 mm (SD 1.3) for OPIs and 0.8 mm (SD 1) for TPIs. 20% of OPIs showed more than 3 mm of bone loss compared with 0.6% for TPIs. When compensating for vertical placement depth, OPIs still showed a lower marginal bone level and thus more exposed threads than TPIs. Depending on the criteria used, the success rate for OPIs was 46.1% or 72.2% compared with 85% or 91.6% for TPIs. Conclusions: The Nobel Direct® and Nobel Perfect® OPIs show lower success rates and more bone resorption than TPIs after 1 year in function. Factors such as implant design, insertion depth, rough surface towards the mucosa, in situ preparation and immediate loading may have an influence on the clinical outcome. [source] Effect of implant design on survival and success rates of titanium oral implants: a 10-year prospective cohort study of the ITI® Dental Implant SystemCLINICAL ORAL IMPLANTS RESEARCH, Issue 1 2004Ioannis K. Karoussis Abstract Aim: The aim of this 10-year study (observation time 8,12 years, mean: 10 years) was to compare the survival rates, success rates and incidences of biological complications using three different implant designs of the ITI® Dental Implant System. Material and methods: In 89 dental patients treated comprehensively, a total of 112 hollow screw (HS), 49 hollow cylinder (HC) and 18 angulated hollow cylinder (AHC) implants were installed depending on the available bone volume and according to prosthetic needs. One and 10 years after surgical placement, clinical and radiographic parameters were assessed. The incidences of peri-implantitis according to various thresholds were registered over 10 years of maintenance. Results: Success criteria at 10 years were set at: pocket probing depth (PPD)5 mm, bleeding on probing (BoP),, bone loss < 0.2 mm annually. The survival rate for HS was 95.4%, for HC 85.7% and for AHC 91.7%. Ninety percent of all the HS, 71% of the HC and 88% of the AHC did not present with an incidence of peri-implantitis over the 10 years, HC having significantly higher incidence of peri-implantitis than HS (P< 0.004). With the success criteria set above, a success rate for HS of 74%, for HC of 63% and for AHC of 61% was identified at 10 years. However, including a definition of PPD6 mm, BoP , and bone loss < 0.2 mm annually for success, the rates for HS were 78%, for HC 65% and for AHC 67%, respectively. Basing success criteria purely on clinical parameters (without radiographic analysis), such as: PPD5 mm and BoP,, the success rates increased to 90%, 76% and 89%, respectively. With PPD6 mm and BoP , as success criteria chosen, the respective rates were 94%, 82% and 94% for HS, HC and AHC implants, respectively. Conclusions: A significantly higher survival rate as well as a significantly lower incidence of peri-implantitis was identified for hollow screw design ITI® Dental Implants after 10 years of service when compared to hollow cylinder design ITI® Dental Implants (95.4% vs. 85.7%; 10% vs. 29%). Depending on the setting of the threshold criteria for success, success rates are highly variable and hence, reporting of success rates with elaboration on the criteria set appears crucial for comparison of different studies. Résumé Le but de ce suivi d'une décennie a été de comparer les taux de survie, les taux de succès et les incidences des complications biologiques de l'utilisation de trois modèles implantaires différents du système ITI® Dental Implant. Chez 89 patients, 112 vis creuses (HS), 49 cylindres creux (HC) et 18 cylindres creux angulés (AHC) ont été placés suivant le volume osseux disponible et les nécessités prothétiques. Une et dix années après leur placement, des paramètres cliniques et radiographiques ont été définis. Les incidences de paroïmplantite relatives aux différents seuils ont été enregistrées durant ces dix années de maintenance. Les succès des critères à dix ans étaient placés à : PPD5 mm, BoP-, perte osseuse <0,2 mm/an. Le taux de survie pour HS était de 95,4%, pour HC de 86% et pour AHC de 92%. Nonante pour cent de tous les HS, 71% des HC et 88% des AHC ne présentaient pas d'incidences de paroïmplantite durant ces dix années, HC ayant une plus importante incidence de paroïmplantite que HS (p<0,004). Grace aux critères de succès indiqués, un taux de succès de 74% pour HS, de 63% pour HC et de 61% pour AHC a été identifié après dix ans. Cependant, en définissant le succès avec PPD6mm, BoP- et perte osseuse <0,2mm/an, les taux étaient de 78% pour HS, de 65% pour HC et de 67% pour AHC. En basant les taux de succès uniquement sur les paramètres cliniques (sans l'analyse radiographique) tels que PPD5 mm et BoP-, les taux de succès augmentaient respectivement à 90, 76 et 89%. Avec PPD6mm et BoP- comme critères de succès, les taux s'élevaient respectivement à 94, 82 et 94%. Un taux de survie significativement plus important ainsi qu'une incidence significativement plus faible de paroïmplantite étaient constatés au niveau des implants vis creuses après dix ans de mise en fonction comparés aux cylindres creux. Suivant l'établissement du seuil pour les critères du succès, les taux de ce succès sont extrêmement variables et rapporter les taux de succès suivant l'élaboration des critères est donc crucial pour comparer différentes études. Zusammenfassung Ziel: Das Ziel dieser 10-Jahresstudie (Beobachtungszeit 8,12 Jahre, Mittelwert: 10 Jahre) war es, bei ITI® -Implantaten mit drei verschiedenen Designs, die Erfolgs- und Überlebensrate zu vergleichen, und das Auftreten von biologischen Zwischenfällen zu untersuchen. Material und Methode: Bei 89 synoptisch behandelten Patienten implantierte man in Abhängigkeit des vorhandenen Knochenvolumens und der prothetischen Anforderungen insgesamt 112 Hohlschraubenimplantate (HS), 49 Hohlzylinderimplantate (HC) und 18 abgewinkelte Hohlzylinderimplantate (AHC). Ein und zehn Jahre nach der Implantation nahm man die klinischen und radiologischen Parameter auf. Eine Periimplantitis registrierte während der 10-jährigen Erhaltungsphase anhand verschiedener Grenzwerte. Resultate: Die Kriterien für einen Erfolg nach 10 Jahren legte man bei den folgenden Werten fest: PPD <5mm, BOP-, jährlicher Knochenverlust <0.2mm. Die Überlebensrate für ein HS lag bei 95.4%, für ein HC bei 85.7% und für ein AHC bei 91.7%. 90% aller HS, 71% aller HC und 88% aller AHC zeigte während den 10 Jahren nie Anzeichen einer Periimplantitis, wobei die HC signifikant häufiger Periimplantitis hatten, als die HS (p<0.004). Mit den oben festgelegten Erfolgskriterien ergab sich nach 10 Jahren für die HS eine Erfolgsrate von 74%, für die HC eine von 63% und für die AHC eine von 61%. Veränderte man die Definition auf "PPD<6mm, BOP -, jährlicher Kochenverlust <0.2mm", so betrugen die Erfolgsraten für die HS 78%, für die HC 65% und für die AHC 67%. Basierten die Erfolgskriterien rein auf klinischen Parametern (PPD <5mm, BOP-, keine röntgenologische Anlyse), so stiegen die Erfolgsraten auf 90%, 76% und 89% an. Wählte man die Erfolgskriterien "PPD <6mm und BOP -", so betrugen die Erfolgsraten für die HS 94%, für die HC 82% und für die AHC 94%. Zusammenfassung: Verglich man nach 10-jähriger Funktion die Hohlschrauben des ITI® -Implantat-Systems mit den Hohlzylindern desselben Systems, so ergab sich für die HS sowohl eine signifikant höher Überlebensrate, wie auch ein selteneres Auftreten von Periimplantitis (95.4% vs. 85.7%; 10% vs. 29%). Die Erfolgsraten variieren in Abhängigkeit der in der Definition eines Erfolges festgelegten Grenzwerten enorm stark. Dies erweist sich im Vergleich von verschiedenen Studien als hinderlich, weil die Definition der Erfolgsraten meist auf verschiedenen Kriterien beruhen. Resumen Intención: La intención de este estudio de 10 años (tiempo de observación 8,12, media: 10 años) fue comparar los índices de supervivencia, índices de éxito e índices de complicaciones biológicas usando tres diferentes diseños de implantes del Sistema de Implantes Dentales ITI®. Material y Métodos: Se instalaron en 89 pacientes dentales tratados completamente un total de 112 tornillos huecos (HS), 49 cilindros huecos (HC) y 18 cilindros huecos angulados (AHC) dependiendo de la disponibilidad de volumen óseo y de acuerdo con las necesidades protésicas. Se valoraron parámetros clínicos y radiográficos uno y diez años tras la colocación quirúrgica. Se registraron las incidencias de periimplantitis de acuerdo con varios umbrales a lo largo de 10 años de mantenimiento. Resultados: Los criterios de éxito a los 10 años se situaron en PPD5mm, BoP-, pérdida ósea < 0.2mm por año. El índice de supervivencia para los HS fue del 95.4%, para los HC del 85.7% y para los AHC del 91.7%. El 90% de los HS, el 71% de los HC y el 88% de los AHC no presentaron ninguna incidencia de periimplantitis a lo largo de los 10 años, HC tuvo una significativamente mayor incidencia de periimplantitis que HS (p< 0.004). Con los criterios de éxito antes mencionados, se identificó un índice de éxito para HS del 74%, para HC del 63% y para AHC del 61% a los 10 años. De todos modos, incluyendo una definición de PPD6mm, BoP, y pérdida ósea <0.2mm al año para tener éxito, los índices para HS fueron del 78%, para HC 65% y para AHC 67%, respectivamente. Basando los criterios de éxito puramente en parámetros clínicos (sin análisis radiográficos), tales como: PPD5mm y BoP-, los índices de éxito subieron hasta el 90%, 76% y 89%, respectivamente. Con el PPD6mm y BoP , como criterios de éxito elegidos, los índices respectivos fueron del 94%,82% y 94% para implantes HS, HC y AHC, respectivamente. Conclusiones: Se identificó un significativamente mayor índice de supervivencia al igual que una menor incidencia de periimplantitis para el diseño de tornillo hueco Implante Dental ITI®. (95.4% vs. 85.7; 10% vs. 29%). Dependiendo de la definición del criterio del umbral de éxito, los índices de éxito son altamente variables y por tanto, los informes de los índices de éxito con elaboración de la definición de criterios parece ser crucial para la comparación de los diferentes estudios. [source] Effect of Compromised Cortical Bone on Implant Load DistributionJOURNAL OF PROSTHODONTICS, Issue 8 2008vanç Akça DDS Abstract Purpose: To investigate photoelastically the difference in load distribution of dental implants with different implant neck designs in intact and compromised bone. Materials and Methods: Composite photoelastic models were fabricated using two different resins to simulate trabecular bone and a 1-mm thick layer of cortical bone. The following parallel-sided, threaded implants were centrally located in individual models representing intact and compromised cortical bone: Straumann (4.1-mm diameter × 12-mm length), AstraTech (4.0-mm diameter × 13-mm length), and 3i (3.75-mm diameter × 13-mm length). The compromised cortical bone condition was simulated by contaminating a 1-mm neck portion with Vaseline to impair the implant,resin interface. Vertical and oblique static loads were applied on the abutments, and the resulting stresses were monitored photoelastically and recorded photograhphically. Results: For the fully intact condition, the highest stresses were observed around the crest and apical region for all implant designs under vertical and inclined loads. There were no appreciable differences in magnitude or distribution between implant types. With compromised cortical bone, for all designs and load directions, higher stresses in the supporting structures were observed. Increased stresses were noted especially at the cortical bone,trabecular bone interface. Somewhat lower stress levels were observed with the 3i implant. Conclusions: The condition of implant,cortical bone contact has considerable influence on stress distribution. A compromised cortical bone condition caused higher level stresses for all implant designs tested. [source] Shape optimization of dental implant designs under oblique loading using the p-version finite element methodJOURNAL OF PROSTHODONTICS, Issue 4 2002Cynthia S. Petrie DDS [source] Evaluating the In Vitro and In Vivo Efficacy of Nano-Structured Polymers for Bladder Tissue Replacement ApplicationsMACROMOLECULAR BIOSCIENCE, Issue 5 2007Megan Pattison Abstract Bladder cancers requiring radical cystectomy, along with congenital and acquired disorders which result in obstruction of the bladder, necessitate surgical measures (including augmentation); such diagnoses bring a clinical need for effective bladder replacement implant designs. Many recent approaches for the design of soft tissue replacement materials have relied on the use of synthetic polymeric substances; unfortunately, the optimal soft tissue implant material is yet to be found. This may, in part, be because current polymeric formulations fail to sufficiently biomimic the neighboring bladder tissue. This study took a brand new approach in designing the next generation of tissue-engineered bladder constructs through the use of nanotechnology, or materials with nanometer (less than 100 nm) surface features. Results provided evidence that nano-structured polymeric scaffolds (specifically, PLGA and PU) created using chemical etching techniques are capable of enhancing the human bladder smooth muscle cell adhesion, proliferation, and the production of extracellular matrix (ECM) proteins. Preliminary in vivo results also speak to the usefulness of such nano-structured materials. In combination, these findings suggest that nano-dimensional PLGA and PU scaffolds are promising replacement materials for the human bladder wall. [source] Finite Element Modelling of Bioactive Contact in Bone-Implant InterfacePROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2008André Lutz Finite element simulation for the prediction of bone remodelling caused by implants is a powerful method to improve or to rate implant designs even before they will be evaluated in clinical studies. But the bone,implant interaction is often modelled as ideal bonding in the interface. This approach is not suitable to describe the interrelation of both parts in a physiological manner. To correct these insufficiencies a 3D bioactive contact element has been developed. This contact element describes on the one hand the pure mechanical interaction and on the other hand the mechanical stimulated bone ingrowth in porous surfaces. The benefits of the use of the bioactive contact element regarding the standard method will be presented in this contribution. A comparison of both methods based on clinic results regarding a hip prosthesis with mixed surface textures will be shown. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] One-Year Prospective Three-Center Study Comparing the Outcome of a "Soft Bone Implant" (Prototype Mk IV) and the Standard Brånemark ImplantCLINICAL IMPLANT DENTISTRY AND RELATED RESEARCH, Issue 2 2003Bertil Friberg DDS ABSTRACT Background: Oral implant treatment ad modum Brånemark has been used for decades in the rehabilitation of edentate and partially dentate patients. Posterior jaw regions frequently exhibit bone of poor texture, and it is often difficult to obtain primary stability. Thus, it may prove beneficial to deviate from the original protocol and to use implants with a modified design, for example, with a slightly tapered geometry. Purpose: The purpose of the investigation was to compare the early behavior of a modified (prototype Mk IV, Branemark System, Nobel Biocare AB, Gothenburg, Sweden; test) implant with that of the standard Brånemark implant (control) in regions of mainly type 4 bone. Materials and Methods: Three Swedish centers participated, and a total of 44 patients were treated with oral implants for 39 maxillas and 5 mandibles. The study focused on the most distal right and left implant sites (88 implants), which were randomized to receive either a test or a control implant. Various parameters were recorded, such as registered insertion torque (OsseoCare, Nobel Biocare AB), wobbling during insertion, primary and secondary stability (as measured with resonance frequency), and marginal bone loss. The implants were followed up for 1 year. Results.: The test implant more frequently required a higher insertion torque and showed a significantly higher primary stability than the control implant. This difference in stability leveled out over time, and test and control implants exhibited similar secondary stability at abutment operation and at the 1-year visit. Wobbling during insertion was rarely recorded for either of the implant designs. The 1-year cumulative success rate was 93.1% for test implants and 88.4% for control implants. Conclusions: The modified implant design resulted in an increased primary stability, which may be important when placing implants in jaw regions of type 4 bone. However, independent of the achieved primary stability, successful implants tended to approach similar secondary stability in the two designs tested. [source] A study of the bone healing kinetics of plateau versus screw root design titanium dental implantsCLINICAL ORAL IMPLANTS RESEARCH, Issue 3 2009Gary Leonard Abstract Objective: This study was designed to compare the bone healing process around plateau root from (PRF) and screw root from (SRF) titanium dental implants over the immediate 12 week healing period post implant placement. Material and methods: 32PRF and 32SRF implants were placed in 8 beagle dogs at 12, 8, 5 and 3 weeks prior to enthanisation using a bilaterally balanced distribution. Undecalcified ground sections were prepared from the biopsies taken and histometric measurements of bone implant contact (BIC) and bone area fraction occupancy (BAFO) were made on the middle 5 mm portion of each 8 mm implant root length. Results: The analysis showed that although measurements of bone to implant contact (BIC) and bone area fraction occupancy (BAFO) tended to be greater for the SRF implants at all four time points, the differences in measurements between implant types did not reach statistical significance (P=0.07, P=0.06). The effect of time on BIC and BAFO was found to be strongly significant for both implant types thus indicating a statistically significant increase in BIC and BAFO overall with time (P=0.004, P=0.002). Furthermore, both PRF and SRF implants behaved similarly over time with measurements of BIC and BAFO progressing in parallel. Histomorphologic analysis of these sections demonstrated the prominent role of woven bone (callus) in the bone healing process around PRF implants. Conclusion: The results can be interpreted to indicate a comparable development of secondary stability for both PRF and SRF implant designs. However, as these parameters reflect the structural connection between implant and bone and not the functional properties of the bone to implant interface, they cannot be regarded as comprehensive measures of osseointegration. This particularly relevant given the reduced load bearing capacity of woven bone. [source] The impact of loads on standard diameter, small diameter and mini implants: a comparative laboratory studyCLINICAL ORAL IMPLANTS RESEARCH, Issue 6 2008Simon Rupert Allum Abstract Objectives: While caution in the use of small-diameter (,3.5 mm) implants has been advocated in view of an increased risk of fatigue fracture under clinical loading conditions, a variety of implant designs with diameters <3 mm are currently offered in the market for reconstructions including fixed restorations. There is an absence of reported laboratory studies and randomized-controlled clinical trials to demonstrate clinical efficacy for implant designs with small diameters. This laboratory study aimed to provide comparative data on the mechanical performance of a number of narrow commercially marketed implants. Materials and methods: Implants of varying designs were investigated under a standardized test set-up similar to that recommended for standardized ISO laboratory testing. Implant assemblies were mounted in acrylic blocks supporting laboratory cast crowns and subjected to 30° off-axis loading on an LRX Tensometer. Continuous output data were collected using Nexygen software. Results: Load/displacement curves demonstrated good grouping of samples for each design with elastic deformation up to a point of failure approximating the maximum load value for each sample. The maximum loads for Straumann (control) implants were 989 N (±107 N) for the 4.1 mm RN design, and 619 N (±50 N) for the 3.3 mm RN implant (an implant known to have a risk of fracture in clinical use). Values for mini implants were recorded as 261 N (±31 N) for the HiTec 2.4 mm implant, 237 N (±37 N) for the Osteocare 2.8 mm mini and 147 N (±25 N) for the Osteocare mini design. Other implant designs were also tested. Conclusions: The diameters of the commercially available implants tested demonstrated a major impact on their ability to withstand load, with those below 3 mm diameter yielding results significantly below a value representing a risk of fracture in clinical practice. The results therefore advocate caution when considering the applicability of implants ,3 mm diameter. Standardized fatigue testing is recommended for all commercially available implants. [source] | |||||||||||||