Osseointegration of zirconia implants compared with titanium : an in vivo study

Background Titanium and titanium alloys are widely used for fabrication of dental implants. Since the material composition and the surface topography of a biomaterial play a fundamental role in osseointegration, various chemical and physical surface modifications have been developed to improve osseous healing. Zirconia-based implants were introduced into dental implantology as an altenative to titanium implants. Zirconia seems to be a suitable implant material because of its tooth-like colour, its mechanical properties and its biocompatibility. As the osseointegration of zirconia implants has not been extensively investigated, the aim of this study was to compare the osseous healing of zirconia implants with titanium implants which have a roughened surface but otherwise similar implant geometries. Methods Forty-eight zirconia and titanium implants were introduced into the tibia of 12 minipigs. After 1, 4 or 12 weeks, animals were sacrificed and specimens containing the implants were examined in terms of histological and ultrastructural techniques. Results Histological results showed direct bone contact on the zirconia and titanium surfaces. Bone implant contact as measured by histomorphometry was slightly better on titanium than on zirconia surfaces. However, a statistically significant difference between the two groups was not observed. Conclusion The results demonstrated that zirconia implants with modified surfaces result in an osseointegration which is comparable with that of titanium implants

Behavior of osteoblastic cells cultured on titanium and structured zirconia surfaces

Background Osseointegration is crucial for the long-term success of dental implants and depends on the tissue reaction at the tissue-implant interface. Mechanical properties and biocompatibility make zirconia a suitable material for dental implants, although surface processings are still problematic. The aim of the present study was to compare osteoblast behavior on structured zirconia and titanium surfaces under standardized conditions. Methods The surface characteristics were determined by scanning electron microscopy (SEM). In primary bovine osteoblasts attachment kinetics, proliferation rate and synthesis of bone-associated proteins were tested on different surfaces. Results The results demonstrated that the proliferation rate of cells was significantly higher on zirconia surfaces than on titanium surfaces (p < 0.05; Student's t-test). In contrast, attachment and adhesion strength of the primary cells was significant higher on titanium surfaces (p < 0.05; U test). No significant differences were found in the synthesis of bone-specific proteins. Ultrastructural analysis revealed phenotypic features of osteoblast-like cells on both zirconia and titanium surfaces. Conclusion The study demonstrates distinct effects of the surface composition on osteoblasts in culture. Zirconia improves cell proliferation significantly during the first days of culture, but it does not improve attachment and adhesion strength. Both materials do not differ with respect to protein synthesis or ultrastructural appearance of osteoblasts. Zirconium oxide may therefore be a suitable material for dental implants

Osseointegration of zirconia implants: an SEM observation of the bone-implant interface

Background The successful use of zirconia ceramics in orthopedic surgery led to a demand for dental zirconium-based implant systems. Because of its excellent biomechanical characteristics, biocompatibility, and bright tooth-like color, zirconia (zirconium dioxide, ZrO2) has the potential to become a substitute for titanium as dental implant material. The present study aimed at investigating the osseointegration of zirconia implants with modified ablative surface at an ultrastructural level. Methods A total of 24 zirconia implants with modified ablative surfaces and 24 titanium implants all of similar shape and surface structure were inserted into the tibia of 12 Gottinger minipigs. Block biopsies were harvested 1 week, 4 weeks or 12 weeks (four animals each) after surgery. Scanning electron microscopy (SEM) analysis was performed at the bone implant interface. Results Remarkable bone attachment was already seen after 1 week which increased further to intimate bone contact after 4 weeks, observed on both zirconia and titanium implant surfaces. After 12 weeks, osseointegration without interposition of an interfacial layer was detected. At the ultrastructural level, there was no obvious difference between the osseointegration of zirconia implants with modified ablative surfaces and titanium implants with a similar surface topography. Conclusion The results of this study indicate similar osseointegration of zirconia and titanium implants at the ultrastructural level

Evaluierung eines Verfahrens zur chemisch-elektrochemischen Abscheidung von Edelmetallüberzügen auf MCrAly-Schichten

Zusammenfassung: Grundlage dieser Forschungsarbeit ist der Wunsch nach höheren Standzeiten und höherer thermischer Belastbarkeit von Turbinenschaufeln bei Hochtemperatur-Gasturbinen. Um dies zu erreichen, besteht die Möglichkeit, die Schutzschicht der Turbinenschaufeln aus MCrAlY mit einem Platinmetall zu beschichten, welches die Diffusionsgeschwindigkeit von Aluminium herabsetzt. Die Diffusionsgeschwindigkeit von Aluminium aus der MCrAlY-Schicht ist ein Maß für die Lebensdauer der Turbinenschaufel. Um die inhomogene Oberfläche der Turbinenschaufeln kostengünstig beschichten zu können soll ein elektrolytisches Beschichtungsverfahren verwendet werden. Elektrolytische Metallabscheidung auf Legierungen zeichnet sich oft durch Haftungsprobleme des Niederschlags auf dem Grundwerkstoff aus. Aus diesem Grund werden spezielle Haftvermittlungsbäder eingesetzt. Da Nickel der Grundwerkstoff von MCrAlY ist, wurden die Haftvermittlungsbäder auf Nickelbasis aufgebaut, wiesen jedoch ohne weitere Vorbehandlung auf der MCrAlY-Schicht keine positiven Haftungsergebnisse auf. Der Schwerpunkt der Arbeit lag deshalb in der Entwicklung verschiedener Aktivierungsverfahren, die teilweise mit Beschichtungsverfahren kombiniert wurden, um eine Haftung durch Adhäsion zu erreichen. Nachdem bei zwei Verfahren mittels Schliffbilder eine einwandfreie Haftung der Nickelschicht nachgewiesen werden konnte, wurde bei einem der beiden Verfahren die Elektropolierfähigkeit bezüglich MCrAlY entdeckt. Die Glättung der MCrAlY-Oberfläche bewirkt eine bessere Haftung der Al2O3-Schicht und erhöht somit die Lebensdauer der Schutzschicht. Deshalb wurde die Kombination von Elektropolieren und Nickelbeschichten eingehend untersucht. Im letzten Teil der Arbeit ist ein Schichtverbund aus elektropoliertem MCrAlY, Nickel und Palladium (Metall aus der Platin-Gruppe) hergestellt worden. Als Belastungstest wurden die Proben bei 1140°C in einer Argonatmosphäre geglüht. Erste Diffusionsergebnisse zeigten eine einwandfreie Schichthaftung, wodurch eine höhere Standzeit ermöglicht wird

Entwicklung eines Herstellverfahrens für Wellenmembranen aus Nickel

Zusammenfassung: In dieser Studienarbeit wird ein Verfahren vorgestellt, mit dem Nickelmembranen galvanisch abgeschieden werden können. Die Membranen werden mechanisch spannungsfrei, flach und gewellt auf einem Membranenbett abgeschieden und von diesem abgelöst. Darüber hinaus werden Flachmembranen mit geringen Zugspannungen selektiv haftend auf einem Gehäuserohling abgeschieden. In einzelnen Versuchen werden die galvanischen Abscheidungsmöglichkeiten (galvanische Zelle, chemische Abscheidung und elektrolytische Abscheidung) bezüglich der Niederschlagseigenschaften überprüft. Für das ausgewählte elektrolytische Verfahren wird eine geeignete Badzusammensetzung angegeben und eine Experimentieranlage aufgebaut. In einzelnen Versuchen werden innere Spannungen, Abscheidungsrate und die Oberflächengüte ermittelt. Eine Besonderheit ist die Vorbehandlung des Membranenträgers, auf dem die bereichsweise haftenden / nichthaftenden Folien durch chemisches Aktivieren und Passivieren niedergeschlagen werden. Es wird gezeigt, daß sich Membrane durch Erzeugung innerer Zugspannung im Nickelniederschlag vom Membranenbett anheben können. Bei der Überspannung der Druckübertragungsbohrung ergaben sich mehrere Möglichkeiten, die noch auf Serienreife zu überprüfen sind. Es wurden spannungsfreie Membranen aus Nickel mit Stärken von 8-50µm abgeschieden. Eine 50µm starke Membranen wurde meßtechnisch mit einer herkömmlich gefertigten Nickelmembranen verglichen. Sie hat fast das gleiche Verhalten, jedoch eine deutlich besserer Oberfläche als die gewalzte. Das gewünschte Endergebnis wurde durch Kombinieren der entwickelten Technologien in Form einer Flachmembrane gefertigt. Die Membran hob sich in der Mitte um 150µm an. Die galvanisch hergestellte Verbindung Membrane/Träger konnte durch Einwirkung von 7,5 bar Überdruck nicht zerstört werden

Influence of Anodizing Stages on the Preload Force of Implant–Abutment Screws and Their Benefits Regarding the Concept of Immediate Implant Placement—An In Vitro Study

The tightening torque applied to a screw in a provisional restoration immediately after implant placement in a fresh extraction socket is often too low to gain sufficient preload force. Therefore, abutment screw loosening is a common complication. The aim of this study was to investigate whether it is possible to increase the preload force of a given tightening torque by anodizing parts of the implant–abutment complex. In test group 1 (TG1), only the abutment screw was anodized, in four different stages, whereas in test group 2 (TG2), the abutment and the threaded sleeve were anodized in four anodizing stages (TG2a–TG2d). The control group (CG) consisted of non-anodized components. The results were tested for normal distribution, and the components were subsequently parametrically analyzed using a linear model. Both test groups showed higher preload forces compared to the non-anodized control group. The CG obtained an average preload force of 390 N at a tightening torque of 35 Ncm. Comparable values were already obtained at a tightening torque of 20 to 30 Ncm in TG1c/D and TG2b/d. It can be concluded that anodization of abutment screws and components is an effective measure to increase the preload force of the abutment screws by a given tightening torque

Is complete re-osseointegration of an infected dental implant possible? Histologic results of a dog study: A short communication

Complete reosseointegration after treatment of periimplantitis was never published yet. This short scientific communication reports about results of a randomized controlled preclinical study. An electrolytic approach was compared to a classical modality (ablative, cotton pellets soaked with sodium chloride solution and H2O2. For electrolytic cleaning a complete reosseointegration was achieved in several cases serving as a proof of concept

Heat generation at the implant–bone interface by insertion of ceramic and titanium implants

Purpose: The aim of this study is to record material- and surface-dependent heat dissipation during the process of inserting implants into native animal bone. Materials and Methods: Implants made of titanium and zirconium that were identical in macrodesign were inserted under controlled conditions into a bovine rib tempered to 37 °C. The resulting surface temperature was measured on two bone windows by an infrared camera. The results of the six experimental groups, ceramic machined (1), sandblasted (2), and sandblasted and acid-etched surfaces (3) versus titanium implants with the corresponding surfaces (4, 5, and 6) were statistically tested. Results: The average temperature increase, 3 mm subcrestally at ceramic implants, differed with high statistical significance (p = 7.163 × 10−9, resulting from group-adjusted linear mixed-effects model) from titanium. The surface texture of ceramic implants shows a statistical difference between group 3 (15.44 ± 3.63 °C) and group 1 (19.94 ± 3.28 °C) or group 2 (19.39 ± 5.73 °C) surfaces. Within the titanium implants, the temperature changes were similar for all surfaces. Conclusion: Within the limits of an in vitro study, the high temperature rises at ceramic versus titanium implants should be limited by a very slow insertion velocity

The effect of in vitro electrolytic cleaning on biofilm-contaminated implant surfaces

Purpose: Bacterial biofilms are a major problem in the treatment of infected dental and orthopedic implants. The purpose of this study is to investigate the cleaning effect of an electrolytic approach (EC) compared to a powder-spray system (PSS) on titanium surfaces. Materials and Methods: The tested implants (different surfaces and alloys) were collated into six groups and treated ether with EC or PSS. After a mature biofilm was established, the implants were treated, immersed in a nutritional solution, and streaked on Columbia agar. Colony-forming units (CFUs) were counted after breeding and testing (EC), and control (PSS) groups were compared using a paired sample t-test. Results: No bacterial growth was observed in the EC groups. After thinning to 1:1,000,000, 258.1 ± 19.9 (group 2), 264.4 ± 36.5 (group 4), and 245.3 ± 40.7 (group 6) CFUs could be counted in the PSS groups. The difference between the electrolytic approach (test groups 1, 3, and 5) and PSS (control groups 2, 4, and 6) was statistically extremely significant (p-value < 2.2 × 10−16). Conclusion: Only EC inactivated the bacterial biofilm, and PSS left reproducible bacteria behind. Within the limits of this in vitro test, clinical relevance could be demonstrated