Einführung: CAD/CAM-Nanohybridkomposite sind als Material für Langzeitprovisorien (LZPV) im Rahmen präprothetischer Versorgungen aufgrund ihrer guten Stabilität und der Möglichkeit der additiven und subtraktiven Formgestaltung bei gleichzeitig geringen Material- und Verarbeitungskosten etabliert. Ob sich Nanohybridkomposite auch für definitive Versorgungen im Seitenzahnbereich als Alternativmaterial zu Keramiken eignen, muss noch geklärt werden. Ziel dieser Studie war es daher, die Belastbarkeit von Seitenzahnbrücken aus einem Nanohybridkomposit (Grandio disc, VOCO GmbH, Cuxhaven, Deutschland) im Vergleich zu formgleichen Brücken aus Lithiumdisilikat-Keramik (IPS e.max CAD, Ivoclar, Schaan, Liechtenstein) nach simulierter Alterung mittels Kausimulation und Thermocycling zu untersuchen. Material/Methoden: Es wurden jeweils acht Seitenzahnbrücken aus Grandio disc und aus IPS e.max CAD im CAD/CAM-Verfahren hergestellt. Die Brücken wurden mittels Adhäsivtechnik (Ceramic Bond/Bifix QM, VOCO GmbH) auf gedruckten Pfeilerstümpfen zementiert. Zur Simulation des Parodonts wurde eine dünne Latexschicht auf die Wurzeläquivalente der gedruckten Stümpfe aufgebracht. Die so vorbereiteten Proben wurden mit den Wurzelanteilen in Polyurethan eingebettet. Die künstliche Alterung erfolgte durch 750.000 Belastungszyklen (50 N) im Kausimulator bei parallel ablaufender Thermowechselbelastung (9.000 Zyklen, 5 °C bis 55 °C). Im Anschluss wurden alle Probekörper einer Bruchlastprüfung bis zum Totalversagen unterzogen. Ergebnisse: Bei den Nanohybridkompositbrücken konnte bereits vor dem Totalversagen bei einer Kraft von 642,4 ± 115,9 N ein Lastabfall beobachtet werden, der jedoch nicht zum Totalversagen führte und als erste plastische Verformung interpretiert wurde. Die Nanohybridkompositbrücken versagten bei einer Kraft von 755,7 N ± 106,1 N, während die aus IPS e.max CAD hergestellten Keramikbrücken bei einer signifikant geringeren Kraft von 573,5 N ± 57,3 N versagten (p = 0,010). Schlussfolgerungen: Hinsichtlich der in dieser Studie erhobenen Parameter präsentiert sich das Nanohybridkomposit als ein vielversprechendes Material für den mittel- und langfristigen intraoralen Einsatz bei definitiven Seitenzahnbrücken. Keywords: CAD-CAM-Materialien, CAD/CAM-Technologie, digitale Zahnmedizin, Nanohybridkomposite, Seitenzahnbrücke

Aim: New technologies such as tactile robots and artificial intelligence (AI) are finding their way into clinical practice in dentistry and could contribute to the improvement of oral health care in the future. The hypothesis of the present in vitro pilot study trial was that a collaborative tactile robot programmed by a dental student could remove interproximal artificial plaque as effectively as a human operator. Materials and methods: Model teeth were fully covered with artificial plaque and set into phantom jaws. First, a robot was programmed by a dental student to perform interproximal cleaning with an interproximal brush. Second, the teeth were covered with artificial plaque again, and the dental student performed the interproximal cleaning manually. Both experiments were repeated five times. Residual plaque was measured with binary pictures. Surface coverage was reported, and the comparison of methods was performed with significance defined at α = 0.05. Results: No statistically significant difference was found in the cleaning result between the robot and the human operator. Conclusion: The results of the present in vitro pilot study indicate that a tactile robot with integrated AI programmed by a dental student can perform interproximal cleaning as effectively as a dental student. Practical implications: In the future, the use of robot assistants to support oral hygiene, eg, in patients with reduced motor skills or impaired vision, should be fur ther investigated. Keywords: dental robots, dentistry, dentronics, human–machine interaction, interdental brush, interdental cleaning, interproximal, oral hygiene, robotics

Einleitung: Das Gesundheitssystem einschließlich der Zahnmedizin verursacht jährlich mehrere Millionen Tonnen Kohlenstoff-Äquivalente, was deutlich macht, wie bedeutend nachhaltiges Gesundheitsmanagement ist. Das Drei-Säulen-Modell der Nachhaltigkeit kann verwendet werden, um nachhaltiges Handeln, das sowohl ökologische als auch wirtschaftliche und soziale Nachhaltigkeit umfasst, in der Zahnmedizin zu fördern. Ergebnisse, Chancen und Limitationen: Es wurden verschiedene Faktoren identifiziert, die die Nachhaltigkeit der zahnmedizinischen Versorgung beeinflussen, unter anderem Ressourcenverbrauch, Abfallaufkommen, Biomaterialien und Mobilität, ebenso wie Limitationen bei der Umsetzung von Nachhaltigkeitskonzepten, z. B. Richt- und Leitlinien und mangelndes Bewusstsein in Bezug auf eine nachhaltige Gesundheitsversorgung. Schlussfolgerung: Die wichtigsten Handlungsfelder von Nachhaltigkeitsstrategien in der Zahnmedizin, die langfristig zu einem effizienteren und verantwortungsvolleren Gesundheitssystem führen können, wurden identifiziert und zusammengefasst. Der Weg zu mehr Nachhaltigkeit sollte Veränderungen verschiedener Faktoren einschließen. Dies ermöglicht neben einer Verringerung des CO2-Fußabdrucks auch eine Kostenreduktion, was zusätzlich einen positiven ökonomischen Effekt hat. Keywords: nachhaltige Entwicklung, Nachhaltigkeit, Umweltbewusstsein, Zahnmedizin

Aim: The aim of the present study was to compare the performance of a tactile collaborative robot programmed by a dental professional (DP) with that of a DP in the removal of surrogate plaque in vitro. Materials and methods: Six typodont teeth in articulated jaws were covered with surrogate plaque and cleaned by a DP with the help of a manual toothbrush (DP/manual) and an electric toothbrush (DP/electric). The experiment was repeated with the help of a collaborative seven-axis tactile robot programmed by a DP handling a manual toothbrush (robot/manual) and an electric toothbrush (robot/electric). All experiments were repeated five times, resulting in a total of N = 30 teeth in each group. Cleaning results were reported as the percentage of surface area with residual plaque. Results: The cleaning results of the DP and the robot showed no significant differences. However, electric toothbrushing was significantly less effective compared with manual toothbrushing (P < 0.05). Conclusion: The present in vitro study indicates that current robot technology may perform the removal of surrogate plaque as efficiently as a DP. In future, this may be helpful to release nursing staff from this time-demanding task that could possibly cause contagion or to support people with reduced motor skills or impaired vision in performing daily oral hygiene. Keywords: dentronics, robotics, dentistry, dental robots, oral hygiene, electric toothbrush, manual toothbrush, human-machine interaction, human-robot interaction

Purpose: Currently, the prevention of periodontal diseases focuses on mechanical removal of pathogenic biofilms combined with oral antiseptics as supportive chemical antibacterial control. Due to the risk of resistance development and side effects of existing antiseptics, the interest in alternative medicine with naturopathic treatment modalities is growing in dentistry. In the present study, the antibacterial effect of the naturopathic oral care product Repha OS and some of its derivatives, based on medicinal plant extracts and essential oils, with a specific focus on added sweeteners, was investigated on periodontal pathogenic and halitosis-associated bacteria. Materials and Methods: The antibacterial efficacy was investigated by agar dilution assay. The minimum inhibitory concentration (MIC) for the bacterial species Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum, Porphyromonas gingivalis, Prevotella intermedia and Solobacterium moorei was determined. Results: A concentration-dependent antibacterial effect on oral bacterial species by Repha OS and its derivatives was demonstrated. For the original product, the maximum MIC was 10% of the calculated test solution concentration in agar for all examined bacterial species. The removal of essential oils reduced the antibacterial efficacy, whereas the displacement or replacement of sweeteners had almost no effect. Conclusion: In addition to other individual effects of the ingredients, the results of this study show that an antibacterial effect of the naturopathic oral care product on the tested oral bacterial species was achieved in vitro. In vivo, the combination of this antibacterial effect with other properties of the various ingredients may be interesting for a holistic approach in preventive dentistry. Keywords: essential oils, medicinal plant extracts, minimum inhibitory concentration (MIC), naturopathic oral care product, periodontal pathogenic or halitosis-associated bacteria

Purpose: To evaluate the load at fracture and influence of artificial aging of posterior teeth occlusal veneers ("table tops") made of two different ceramics. Materials and Methods: A total of 80 table tops were produced from feldspathic ceramic (VM) and zirconia-reinforced lithium silicate ceramic (CD) using computer-aided design/computer-assisted manufacturing (CAD/CAM). Half of the specimens from each ceramic were aged prior to the load test. Results: Mean ± standard deviation (SD) load at fracture was significantly higher for CD (1,571.1 N ± 297.0 N) than for VM (573.6 N ± 86.4 N) (P .001). After aging, load at fracture increased significantly to 1,819.0 N (± 310.6 N) for CD and to 745.2 N (± 168.3 N) for VM. Conclusion: The use of zirconia-reinforced lithium silicate ceramic for molar nonprep table tops should be uncomplicated according to the high load-at-fracture values. Mechanical stability of either ceramic is not compromised by aging.

Purpose: Since bacterial leakage along the implant-abutment interface may be responsible for peri-implant infections, a realistic estimation of the interface gap width during function is important for risk assessment. The purpose of this study was to compare two methods for investigating microgap formation in a loaded dental implant, namely, microcomputed tomography (micro-CT) and three-dimensional (3D) nonlinear finite element analysis (FEA); additionally, stresses to be expected during loading were also evaluated by FEA. Materials and Methods: An implant-abutment complex was inspected for microgaps between the abutment and implant in a micro-CT scanner under an oblique load of 200 N. A numerical model of the situation was constructed; boundary conditions and external load were defined according to the experiment. The model was refined stepwise until its load-displacement behavior corresponded sufficiently to data from previous load experiments. FEA of the final, validated model was used to determine microgap widths. These were compared with the widths as measured in micro-CT inspection. Finally, stress distributions were evaluated in selected regions. Results: No microgaps wider than 13 μm could be detected by micro-CT for the loaded implant. FEA revealed gap widths up to 10 μm between the implant and abutment at the side of load application. Furthermore, FEA predicted plastic deformation in a limited area at the implant collar. Conclusion: FEA proved to be an adequate method for studying microgap formation in dental implant-abutment complexes. FEA is not limited in gap width resolution as are radiologic techniques and can also provide insight into stress distributions within the loaded complex. Keywords: dental implant, finite element analysis, microcomputed tomography, microgap formation, preload, tightening torque

Die restaurative Versorgung mit Zahnersatz stellt ein komplexes Aufgabengebiet in der Zahnmedizin dar, dessen Bedeutung aufgrund der demographischen Entwicklung in der Zukunft weiter zunehmen wird. Bei der Etablierung geeigneter Therapiemaßnahmen spielt neben Funktionalität, Akzeptanz und Aufwand vor allem die Verträglichkeit mit dem Patientengewebe eine entscheidende Rolle. Der Beitrag erörtert die Biokompatibilität verschiedener Werkstoffgruppen aus der zahnärztlichen Prothetik, stellt Untersuchungen zur Einschätzung der biologischen Verträglichkeit vor und zeigt die möglichen Konsequenzen bei der Verwendung unverträglicher Materialien auf. Keywords: Biokompatibilität, Zytotoxizität, Materialverträglichkeit, dentalrestaurative Materialien, Korrosion

Objectives: To investigate the formation of oral biofilm on various dental ceramics in vivo. Method and Materials: Five different ceramic materials were included: a veneering glass- ceramic, a lithium disilicate glass-ceramic, a yttrium-stabilized zirconia (Y-TZP), a hot isostatically pressed (HIP) Y-TZP ceramic, and an HIP Y-TZP ceramic with 25% alumina. Test specimens were attached to individually designed acrylic appliances; five volunteers wore these appliances for 24 hours in the maxillary arch. After intraoral exposure, the samples were removed from the appliances and the adhering biofilms vitally stained. Then, the twodimensional surface coating and thickness of the adhering biofilm were determined by confocal laser scanning microscopy. Statistical analysis was performed using one-way ANOVA with the level of significance set at .05. Results: Significant differences (P .001) in the bacterial surface coating and in the thickness of the biofilm were found between the various ceramic materials. The lowest surface coating (19.0%) and biofilm thickness (1.9 µm) were determined on the HIP Y-TZP ceramic; the highest mean values were identified with the lithium disilicate glass-ceramic (46.8%, 12.6 µm). Conclusion: Biofilm formation on various types of dental ceramics differed significantly; in particular, zirconia exhibited low plaque accumulation. In addition to its high strength, low plaque accumulation makes zirconia a promising material for various indications (including implant abutments and telescopic crowns) that previously were met only with metal-based materials. Keywords: bacteria, biofilm, dental ceramics, in vivo, zirconia

The aim of the present in vivo study was to examine the effect of polytetrafluoroethylene (PTFE) surfaces on biofilm formation on dental implant abutments in comparison to titanium surfaces. Fifteen modified abutments with incorporated PTFE plates were inserted in 10 patients for 14 days. Scanning electron microscopy techniques were used to examine biofilm formation on different surfaces and to determine the percentage of surface coverage. Significantly less biofilm was detected on PTFE surfaces than on titanium surfaces. The results of this study reveal that PTFE surfaces reduce biofilm formation to a minimum on dental implant abutments.