Load-bearing capacity of screw-retained CAD/CAM-produced titanium implant frameworks (I-Bridge®2) before and after cyclic mechanical loading

Implant-supported screw-retained fixed dental prostheses (FDPs) produced by CAD/ CAM have been introduced in recent years for the rehabilitation of partial or total endentulous jaws. However, there is a lack of data about the long-term mechanical characteristics. OBJECTIVE: The aim of this study was to investigate the failure mode and the influence of extended cyclic mechanical loading on the load-bearing capacity of these frameworks. MATERIAL AND METHODS: Ten five-unit FDP frameworks simulating a free-end situation in the mandibular jaw were manufactured according to the I-Bridge®2-concept (I-Bridge®2, Biomain AB, Helsingborg, Sweden) and each was screw-retained on three differently angulated Astra Tech implants (30º buccal angulation/0º angulation/30º lingual angulation). One half of the specimens was tested for static load-bearing capacity without any further treatment (control), whereas the other half underwent five million cycles of mechanical loading with 100 N as the upper load limit (test). All specimens were loaded until failure in a universal testing machine with an occlusal force applied at the pontics. Load-displacement curves were recorded and the failure mode was macro- and microscopically analyzed. The statistical analysis was performed using a t-test (p=0.05). RESULTS: All the specimens survived cyclic mechanical loading and no obvious failure could be observed. Due to the cyclic mechanical loading, the load-bearing capacity decreased from 8,496 N±196 N (control) to 7,592 N±901 N (test). The cyclic mechanical loading did not significantly influence the load-bearing capacity (p=0.060). The failure mode was almost identical in all specimens: large deformations of the framework at the implant connection area were obvious. CONCLUSION: The load-bearing capacity of the I-Bridge®2 frameworks is much higher than the clinically relevant occlusal forces, even with considerably angulated implants. However, the performance under functional loading in vivo depends on additional aspects. Further studies are needed to address these aspects

Plant-based oral care product exhibits antibacterial effects on different stages of oral multispecies biofilm development in vitro

Background: Excessive biofilm formation on surfaces in the oral cavity is amongst the main reasons for severe infection development like periodontitis and peri-implantitis. Mechanical biofilm removal as well as the use of adjuvant antiseptics supports the prevention of pathogenic biofilm formation. Recently, the antibacterial effect of the oral care product REPHA-OS®, based on medicinal plant extracts and essential oils, has been demonstrated on oral pathogens grown on agar plates. In the present study, the effectiveness of the product on medical relevant oral biofilm development should be demonstrated for the first time. Methods: An established in vitro oral multispecies biofilm, composed of Streptococcus oralis, Actinomyces naeslundii, Veillonella dispar and Porphyromonas gingivalis, was used to analyze the antibacterial effect of different REPHA-OS® concentrations on planktonic bacteria, biofilm formation and mature biofilms. It was quantified using metabolic activity assays and live/dead fluorescence staining combined with three-dimensional confocal laser-scanning microscopy. Additionally, effects on species distribution inside the biofilm were assessed by means of quantitative real-time PCR. Results: REPHA-OS® showed statistically significant antimicrobial effects on all stages of biofilm development: a minimal inhibitory concentration of 5% could be detected for both, for planktonic bacteria and for biofilm formation. Interestingly, only a slightly higher concentration of 10% was necessary to completely kill all bacteria in mature biofilms also. In contrast, an influence on the biofilm matrix or the species distribution could not be observed. The effect could be attributed to the herbal ingredients, not to the contained ethanol. Conclusion: The strong antibacterial effect of REPHA-OS® on different stages of oral biofilm development strengthens its application as an alternative adjuvant in oral care therapies

Geschichte und Positionierung des NIFE : Eine Einführung

[no abstract available

Enzyme-Responsive Nanoparticles and Coatings Made from Alginate/Peptide Ciprofloxacin Conjugates as Drug Release System

Infection-controlled release of antibacterial agents is of great importance, particularly for the control of peri-implant infections in the postoperative phase. Polymers containing antibiotics bound via enzymatically cleavable linkers could provide access to drug release systems that could accomplish this. Dispersions of nanogels were prepared by ionotropic gelation of alginate with poly-L-lysine, which was conjugated with ciprofloxacin as model drug via a copper-free 1,3-dipolar cy-cloaddition (click reaction). The nanogels are stable in dispersion and form films which are stable in aqueous environments. However, both the nanogels and the layers are degraded in the presence of an enzyme and the ciprofloxacin is released. The efficacy of the released drug against Staphylococcus aureus is negatively affected by the residues of the linker. Both the acyl modification of the amine nitrogen in ciprofloxacin and the sterically very demanding linker group with three annel-lated rings could be responsible for this. However the basic feasibility of the principle for enzyme-triggered release of drugs was successfully demonstrated

Influence of 10-MDP Adhesive System on Shear Bond Strength of Zirconia-Composite Interfaces

Abstract Introduction: This in-vitro study investigated the initial 24h bond strength between different composites and zirconia after application of four different adhesive systems. Methods: A total of 120 specimens of zirconia (InCoris, Sirona, Germany, Bernsheim) were ground with a 165 µm grit rotating diamond disc. Thirty specimens were each additionally treated with Cimara Zircon "CZ" (VOCO GmbH, Germany, Cuxhaven), Futurabond U "FBU" (VOCO GmbH), Futurabond M+ "FBM" (VOCO GmbH) or Futurabond M+ in combination with the DCA activator "FBMD" (VOCO GmbH). One of three different types of compositesBifixSE ("BS"), BifixQM ("BQ") or GrandioSO ("G") (VOCO GmbH) -was bonded to ten specimens each in every group. Shear bond strength (SBS) was determined in a universal testing machine. Statistical analysis was performed with ANOVA and the Tukey test. Results: FBM and FBMD gave higher SBS than CZ and FBU in combination with all tested composites. In comparison to FBU, FBM gave statistically significant increases in SBS with BifixSE (19.4±5.7 MPa) (P<0.013) and with GrandioSO (19.1±4.4 MPa) (P<0.021). None of the other comparisons was statistically significant. Conclusion: The new 10-MDP-containing adhesive systems FBM and FBMD increases initial SBS between composites and zirconia in comparison to CZ and FBU

Biofilmvolumen und Azidifizierung in den ersten in situ auf bukkal und palatinal exponiertem Bracketmaterial gebildeten Biofilmen

Purpose: Acidification by bacterial biofilms at the bracket/tooth interface is one of the most common problems in fixed orthodontic treatments, which can lead to white spot lesions (WSL) and caries. As lingual brackets were shown to exhibit reduced WSL formation clinically, the aim of this in situ study was to compare initial intraoral biofilm formation and acidification on bracket-like specimens placed buccally and palatally in the upper jaw as a possible cause for this observation. Methods: Intraoral biofilm was collected from splints equipped with buccally and palatally exposed test specimens, which were worn by 12 volunteers for a total of 48 h. The test specimens consisted of standard bracket material cylinders on top of a hydroxyapatite disc to represent the bracket/tooth interface. They were analyzed for three-dimensional biofilm volume and live/dead distribution by fluorescence staining and confocal laser scanning microscopy as well as for acidification by fluorescence-based pH ratiometry. Results: Similar general biofilm morphology with regard to volume and viability could be detected for buccally and palatally exposed specimens. For pH values, biofilms from both positions showed increased acidification at the bottom layer. Interestingly, the pH value at the top layers of the biofilms was slightly lower on palatally than on buccally exposed specimens, which may likely be due to anatomic conditions. Conclusion: Based on the results of this study, initial intraoral biofilm formation and acidification is almost similar on the bracket material/biomimetic tooth interface when placed buccally or palatally in the upper jaw. As lingual brackets were shown to exhibit reduced WSL formation clinically, future studies should investigate further factors like bracket geometry.Zielsetzung: Die durch bakterielle Biofilme verursachte Ansäuerung an der Bracket/Zahn-Grenzfläche ist eines der häufigsten Probleme während der festsitzenden kieferorthopädischen Behandlung, das zu White-Spot-Läsionen (WSL) und Karies führen kann. Da linguale Multibracketapparaturen klinisch eine verminderte WSL-Bildung aufweisen, war das Ziel dieser In-situ-Studie, die initiale intraorale Biofilmbildung und Ansäuerung an bukkal und palatinal im Oberkiefer platzierten Bracket-ähnlichen Probekörpern als mögliche Ursache zu analysieren. Methoden: Mit Probekörpern bestückte Miniplastschienen dienten der intraoralen Biofilmgewinnung in 12 Probanden für insgesamt 48 h. Die Probekörper wurden bukkal und palatinal platziert und bestanden aus Standard-Bracketmaterialzylindern, welche auf Hydroxylapatitscheiben befestigt wurden, sodass die Bracket/Zahn-Grenzfläche imitiert werden konnte. Die Analyse des dreidimensionalen Biofilmvolumens und der Lebend/tot-Verteilung erfolgte durch Fluoreszenzfärbung und konfokale Laserscanningmikroskopie. Die Auswertung der Ansäuerung erfolgte durch fluoreszenzbasierte pH-Ratiometrie. Ergebnisse: In Bezug auf das Volumen und die Viabilität konnte für bukkal und palatinal exponierte Probekörper eine allgemein ähnliche Biofilmmorphologie nachgewiesen werden. An beiden Positionen war eine erhöhte Ansäuerung in den unteren Schichten des Biofilms zu detektieren. Interessanterweise war der pH-Wert in den obersten Schichten der Biofilme bei palatinal positionierten Probekörpern etwas niedriger als bei bukkal positionierten Probekörpern, was vermutlich durch anatomische Gegebenheiten bedingt ist. Schlussfolgerung: Basierend auf den Ergebnissen dieser Studie ist die initiale intraorale Biofilmbildung und Ansäuerung an der Grenzfläche zwischen Bracketmaterial und biomimetischem Zahn bei bukkaler bzw. palatinaler Platzierung im Oberkieferbereich ähnlich. Da linguale Multibracketapparaturen klinisch eine reduzierte WSL-Bildung aufweisen, sollten zukünftige Studien weitere Faktoren wie die Bracketgeometrie untersuchen

Nanoporous silica nanoparticles with spherical and anisotropic shape as fillers in dental composite materials

The objective of this study was to test whether nanoporous silica nanoparticles can be employed as fillers in dental composite materials to improve their mechanical properties. These nanoporous silica nanoparticles were synthesized using sol-gel methods, in part modified by silanization, and thoroughly characterized. The nanoporous nanoparticles were added to dental resins to form nanocomposites (resins impregnated with nanoparticles) and hybrid composites (containing in addition conventional microfillers). The incorporation of these nanoporous nanoparticles in dental resins or composites was characterized by investigation of the complex viscosity and double bond conversion as well as by determination of flexural strength and Young's modulus. The dispersion of the nanofillers was examined by SEM and EDX imaging of fracture surfaces. Incorporation of small contents (1-3 wt%) of unmodified nanoporous particles leads to improved mechanical properties. However, the incorporation of larger contents results in particle agglomeration and declining mechanical properties. This effect is less pronounced when the surface of the particles is modified with methacrylate residues, resulting in a lower agglomeration tendency and a more homogeneous filler dispersion. Surface properties and, concomitantly, dispersibility of the nanoparticles have a strong influence on mechanical properties. But the incorporation of nanoporous instead of solid nanoparticles into dental composite materials is indeed a possibility to improve the mechanical behavior. However, modification of the surface is necessary and the key to achieving uniform dispersion and, thereby, improving mechanical properties

Effect of sandblasting on the surface roughness and residual stress of 3Y-TZP (zirconia)

A defined surface roughness is important for the adhesive bonding of veneering ceramic to zirconia frameworks. Thus, we investigated the effects that sandblasting has upon the surface roughness and residual stress of zirconia. So as to achieve well-defined blasting parameters and also generate highly reproducible results; a custom-made, automated sandblasting machine was constructed (based on a 3D-printer construction kit). Thirty-two samples (measuring 30 mm × 35 mm × 0.2 mm) were cut from densely sintered 3Y-TZP blanks and then ground with a 45 µm grinding disc. After undergoing regeneration firing, the samples were sandblasted with varying working parameters: blasting angle (45°, 60° and 90°); blasting pressure (2 bar, 4 bar and 6 bar); and working distance (0.5 cm, 1.0 cm and 1.5 cm). The sandblasting path was chosen so as to create samples with an even surface roughness. Changes in blasting pressure resulted in the greatest changes in the surface roughness, the highest surface roughness values were achieved with sandblastings perpendicular to the sample surface. Furthermore, a correlation was found between the mean surface roughness and the residual stress

Multilayered Adsorption of Commensal Microflora on Implant Surfaces: an Unconventional and Innovative Method to Prevent Bacterial Infections Associated with Biomaterials

Biomaterials may be colonized with infectious biofilms and this frequently leads to progressive loss of tissue. Bacteria encased within biofilms resist antibiotics and the host immune system. With life-threatening complications and the antibiotic resistance crisis, novel therapeutic approaches are essentially required to treat biofilm infections. Commensal microflora—particularly streptococci—modulate the immune system's ability to protect from pathogens. In imitation of this natural phenomenon, the present study describes a novel method of applying the commensal, Streptococcus oralis, as a coating on implants to prevent infectious biofilms. Implants are coated with a simple thermal process to circumvent sepsis persuaded by live microflora and for a stable multilayered coating. Titanium discs coated with S. oralis antagonize the biofilm-making capabilities of single, dual, or multispecies periodontal pathogens: Porphyromonas gingivalis, Treponema denticola, Veillonella dispar, and Actinomyces naeslundii—under both static and flow conditions. The bacterial adhesion force measured with atomic force microscopy (AFM) reduces on coated titanium suggesting that electrostatic interactions are mainly responsible for the decrease in maximum adhesion peak. Importantly, S. oralis coated implants are compatible with human gingival fibroblasts. S. oralis coating may provide a potent novel approach to prevent potentially fatal biofilm infections on biomaterials

Nonlinear laser scanning microscopy of oral multispecies-biofilms: Fixative induced fluorescence as a fast and economical in vitro screening method

In this letter we report a fast and easy method which could be used for initial screening of multispecies-biofilm development on putative new dental implant materials. Most staining methods require numerous washing steps that can result in detachment of loosely bound biofilms and therefore falsify the results. Thus, we used glutaraldehyde fixation, which induces autofluorescence through bacterial membrane protein cross-linking and concurrently stabilizes the biofilm structure. We analyzed the biofilms with nonlinear laser scanning microscopy and were able to (I) evaluate the multispecies-biofilm growth and (II) distinguish between bacterial species based on different two-photon autofluorescence intensities. © 2016 by De Gruyter