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Posterior Implants (posterior + implant)
Selected AbstractsBone reactions to longstanding functional load at implants: an experimental study in dogsJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 9 2005T. Berglundh Abstract Objectives: The aims of the present investigation were (i) to study marginal bone level alterations following implant installation, abutment connection and functional loading and (ii) to analyse bone tissue reactions to functional load. Material and Methods: Six beagle dogs, about 1-year old, were used. All mandibular pre-molars were extracted. Three months later four implants of the Astra Tech Implants® Dental System were installed in one side of the mandible and four standard fixtures of the Brånemark System® were placed in the contralateral side of the mandible. Abutment connection was performed 3 months later and a plaque control programme was initiated. Three months after abutment connection fixed partial dentures (FPDs) made in gold were cemented to the maxillary canines and pre-molars. FPDs were also connected to the three posterior implants in each side of the mandible, while the mesial implant in each side was used as an unloaded control. Radiographs were obtained from all implant sites following implant installation, abutment connection and FPD placement. Ten months after the FPD placement the radiographic examination was repeated. The animals were sacrificed and biopsies from all implant sites were obtained and prepared for histological analysis. Results: The radiographic analysis revealed that largest amount of bone loss occurred following implant installation and abutment connection and that this loss was more pronounced at Brånemark than at Astra implants. The bone level alterations that were observed at implants exposed to 10 months of functional load in both implant systems were small and did not differ from control sites. The histological analysis revealed that implants exposed to functional load exhibited a higher degree of bone-to-implant contact than control implants in both implant systems. Conclusion: It is suggested that functional load at implants may enhance osseointegration and does not result in marginal bone loss. [source] Influence of Attachment Systems on Load Transfer of an Implant-Assisted Maxillary OverdentureJOURNAL OF PROSTHODONTICS, Issue 4 2004Mete I. Fanuscu DDS Purpose: This photoelastic study compared the load transfer characteristics of 2 retention mechanisms in an implant-assisted overdenture prosthesis. Materials and Methods: Four implants were incorporated into a photoelastic model of a moderately resorbed edentulous human maxilla. Two retention mechanisms were studied by changing components on the same model and the palateless overdenture. The retention mechanisms studied were bar splint with anterior clip and distal resilient attachments, and solitary ball/O-ring attachments. Loads, ranging from 1.4 to 14.4 kg, were applied to the palatal incline of central incisors and buccal incline of premolars with and without balancing contacts. Stresses developed around all the implants under each loading condition were photographed in the field of a circular polariscope. Results: With both retention mechanisms, protrusive and laterotrusive loads without balancing contacts caused instability of the overdenture, producing minimal stress around the implants in the supporting structure. High intensity stresses indicating intrusion of the posterior implants were noted when the bar/distal resilient attachment overdenture had balancing contacts for protrusive and laterotrusive loads. The posterior implants of ball/O-ring attachment overdenture exhibited high intensity stresses indicating not only intrusion, but also bending, when the occlusion was balanced. Conclusions: Balanced occlusion was required in both retention mechanisms for stability of the implant-assisted overdenture when clinically acceptable loads were applied. The protrusive and laterotrusive loads were not distributed equitably in either mechanism, since highest stresses occurred at the posterior implants. [source] Stability Measurements of Osseointegrated Implants Using Osstell in Partially Edentulous Jaws after 1 Year of Loading: A Pilot StudyCLINICAL IMPLANT DENTISTRY AND RELATED RESEARCH, Issue 3 2002Piero Balleri MD ABSTRACT Background: The introduction of resonance frequency analysis (RFA) as a commercially available technique has made it possible to measure implant stability in implant stability quotient (ISQ) units at any time during the course of implant treatment and loading. However, no information on normal ISQ levels can be found in the literature. Purpose: The aim of this pilot study was to measure the stability of clinically successful implants in partially edentulous patients after 1 year of loading and to study the influence of jaw, anterior/posterior position, implant length, and marginal bone level on implant stability. Materials and Methods: Fourteen partially edentulous patients previously treated with 45 implants were subjected to clinical and radiographie evaluations and RFA measurements using Osstell (Integration Diagnostics, Sävedalen, Sweden) after 1 year of loading. Results: All 45 implants were stable, and implant stability levels were in the range of 57 to 82 ISQ units with a mean of 69 ± 6.5 ISQ after 1 year of loading. Mandibular implants were more stable than were maxillary ones. There were no differences between anterior and posterior implants. No correlation could be found between implant length and stability. Only minor marginal bone resorption was observed. Conclusions: The results from this limited material showed that successfully integrated implants have ISQ levels from 57 to 82 ISQ with a mean of 69 ISQ after 1 year of loading. Mandibular implants are more stable than are maxillary ones. High implant stability can be achieved with short implants and placement in posterior regions. [source] Human ex vivo bone tissue strains around immediately loaded implants supporting maxillary overdenturesCLINICAL ORAL IMPLANTS RESEARCH, Issue 6 2005vanç Akça Abstract Purpose: To evaluate ex vivo bone tissue strains around maxillary implants supporting immediately loaded bar-retained overdentures. Material and methods: Ninety degree two-element rosette strain gauges were bonded on the labial bone of four ITI® dental implants placed in the maxillary anterior region of four completely edentulous maxilla of fresh human cadavers. The installation torque value (ITV) of each implant was measured by a custom-made torque wrench and resonance frequency analyses (RFAs) were undertaken. A bar-retained overdenture was fabricated for each cadaver, and two miniature load cells were integrated in the first molar region of the overdentures for controlled loading experiments. Strain measurements were performed at a sample rate of 10 kHz and under a maximum load of 100 N, simultaneously monitored from a computer connected to a data acquisition system. Finally, removal torque values (RTVs) of the implants were measured. Results: RFA values did not mirror ITVs, while RTVs of implants were slightly lower than the ITVs. Any correlation could not be obtained between RFA values and ITVs or RTVs. Maximum strains around loaded implants ranged between ,100 and ,550 ,, under 25,100 N. The axial and lateral strain values of posterior implants of both sides were higher than those of anterior implants under all loads (P<0.05). Conclusion: Because occlusal forces in humans tend to decrease because of age-related factors, maximum strains around immediately loaded implants supporting maxillary overdentures fall within physiologic levels. Résumé Le but de cette étude a été d'évaluer les tensions du tissu osseux ex vivo autour d'implants maxillaires portant des prothèses amovibles retenues sur une barre placée immédiatement après l'insertion des implants. Deux jauges de force en rosette à 90° ont été attachées au côté lingual de l'os de quatre implants dentaires ITI® placés dans la région antérieure du maxillaire de quatre cadavres humains frais aux maxillaires édentées. La valeur du couple de torsion lors de l'installation (ITV) de chaque implant a été mesurée par un couple fabriqué et des analyses de fréquence de résonnance (RFA) ont été faites. Une prothèse retenue par une barre a été fabriquée pour chaque cadavre et deux cellules de charge miniatures ont été intégrées dans la région de la première molaire de ces prothèses pour les expériences de charge contrôlées. Les mesures de force ont été effectuées à un taux d'échantillonnage de 10 kHz et sous une charge maximale de 100 N, suivies simultanément par un ordinateur connectéà un système d'acquisition de données. Finalement les valeurs des couples de torsion à l'enlèvement (RTV) des implants ont été mesurées. Les valeurs RFA n'étaient pas en ligne avec les ITV tandis que les RTV des implants étaient légèrement inférieurs aux ITV. Aucune corrélation n'a pûêtre établie entre les valeurs RFA et ITV ou RTV. Les forces maximales autour des implants chargés s'étalaient de ,100 ,e à,550 ,e sous 25 N à 100 N. Les valeurs des forces axiales et latérales des implants postérieurs des deux côtés étaient supérieures à celles des implants antérieurs sous toutes les charges (P<0.05). Zusammenfassung Ziel: Es war das Ziel dieser Arbeit, an bis vor kurzem vitalen Knochengewebe Spannungen um Oberkieferimplantate zu untersuchen, welche sofortbelastete und stegverankerte Hybridprothesen tragen. Material und Methoden: Auf den labialen Knochen von vier ITI-Implantaten in der vorderen Region des zahnlosen Oberkiefers von vier frisch verstorbenen Menschen klebte man Dehnmessinstrumente an. Man mass den Wert der Eindrehkraft (ITV) jedes einzelnen Implantates mit einem handelsblichen Drehmomentschlssel und fhrte eine Resonanzfrequenzanalyse (RFA) durch. Man stellte fr jede Leiche eine stegverankerte Hybridprothese her und man baute in der Region der ersten Molaren zwei kleine Messgerte ein, die kontrollierte Belastungsexperimente erlaubten. Dehnmessungen fhrte man mit einer Frequenz von 10 kHz und einer maximalen Belastung von 100 N durch, simultan aufgezeichnet von einem mit dem Messsystem verbundenen Komputer. Schliesslich mass man auch die Krfte, die es brauchte um die Implantate wieder auszudrehen (RTV). Resultate: Die RFA wiederspiegelte die ITV-Werte nicht, whrenddem die RTV-Werte der Implantate geringfgig tiefer waren als die ITV-Werte. Man konnte weder zwischen der RFA, den ITV-Werten oder den RTV-Werten eine Korrelation herstellen. Die maximalen Dehnungen um die Implantate erreichte Werte zwischen ,100 E und ,550 E bei einer Belastung zwischen 25 N und 100 N. Die axialen und lateralen Dehnkrfte bei posterioren Implantaten waren unter smtlichen getesteten Belastungen beidseits grsser als diejenigen der anterioren Implantate (P<0.05). Resumen Propósito: Evaluar las tensiones del tejido óseo ex vivo alrededor de implantes maxilares soportando sobredentaduras retenidas por barras con carga inmediata. Material y Métodos: Se pegaron dos indicadores de tensión de roseta de dos elementos de 90° en el hueso labial de cuatro implantes dentales ITI® colocados en la región maxilar anterior de cuatro maxilares completamente edéntulos de cadáveres humanos frescos. Se midió el valor del torque de instalación (ITV) de cada implante por medio de una chicharra de torque hecha a medida y se llevó a cabo análisis de frecuencia de resonancia (RFA). Se fabricó una sobredentadura retenida por barras para cada cadáver y se integraron dos células miniatura de carga en la región del primer molar de las sobredentaduras para los experimentos de carga controlada. Se llevaron a cabo mediciones de la tensión a un índice de muestra de 10 kHz y bajo una carga máxima de 100 N, simultáneamente monitorizada desde un ordenador conectado a sistema de adquisición de datos. Finalmente, se midieron los valores del torque de remoción (RTV) de los implantes. Resultados: Los valores de RFA no se reflejaron en los ITVs, mientras que los RTVs de los implantes fueron ligeramente más bajos que los ITVs. No se pudieron obtener correlaciones entre los valores de RFA y los ITVs o RTVE. Las tensiones máximas alrededor de los implantes cargados variaron entre ,100 ,, y ,550 ,, bajo 25 N a 100 N. Los valores de las tensiones axiales y laterales de los implantes posteriores de ambos lados fueron mayores que aquellos implantes anteriores bajo todas las cargas (P<0.05). [source] | ||||||||||