Ioannidis, Alexis

Die Aufhellung verfärbter Zähne mithilfe von Bleaching stellt eine minimalinvasive und wirkungsvolle Methode dar, um ästhetische Verbesserungen ohne Substanzverlust zu erreichen. Insbesondere das interne Bleichen wie die „Walking bleach“-Technik bietet bei devitalen Zähnen eine effektive Möglichkeit, selbst intensive Verfärbungen aufzuhellen, die von subgingival durchscheinen. Vor einer prothetischen Versorgung kann das Bleichen als Vorbehandlung die Basis für ein ästhetisches Gesamtbild schaffen und somit den Erfolg und die Langlebigkeit der Restaurationen unterstützen. Für den langfristigen Behandlungserfolg sind bei internen Bleichmaßnahmen sorgfältige endodontische Maßnahmen entscheidend. Eine suffiziente Wurzelfüllung und ein dichter zervikaler Verschluss minimieren das Risiko zervikaler Resorptionen, während sich durch eine regelmäßige Nachsorge mögliche Komplikationen (vor allem bei Traumazähnen) frühzeitig erkennen lassen. Durch die Kombination von präprothetischem Bleichen und gezielten prothetischen Maßnahmen kann ein ästhetisch optimales Ergebnis erzielt werden, das den individuellen Bedürfnissen der Patient/-innen gerecht wird. Manuskripteingang: 13.01.2025, Manuskriptannahme: 05.02.2025 Keywords: Frontzahnästhetik, Zahnverfärbung, Bleaching, Vorbehandlung, Zahnaufhellung

Purpose: To investigate, via questionnaire, how protocols for adhesive luting workflows of dental restorations are applied in three German-speaking countries. Material and Methods: A 47-item questionnaire gathered data on airborne particle abrasion (APA) unit characteristics, parameters, operating procedures, pretreatments in adhesive luting workflows for restorations, and participant demographics. The survey was distributed via trade journals, expert associations, universities, technical schools, and social media. Marginal absolute and relative frequencies were analyzed (95% confidence intervals), with Chi-squared tests comparing observed and expected frequencies (P0.05). Twenty-three experts voted on 23 recommendations regarding APA parameters and other pretreatments for bonding restorations. Results: A total of 267 participants completed the survey. Access to an APA unit was linked to a higher likelihood of performing APA before placement. Approximately half of the participants used APA in their practice. For zirconia restorations, 47.2% applied alumina APA at 50 µm/0.1 MPa, while 36.7% used the same settings for polymer-based restorations. For alloys, 37.5% employed 110 µm/0.2 MPa. These preferences correlated with age (≥30 years), experience (≥10 years), profession (dental technician/dentist), prior instruction/training, and daily APA use. Adhesives with MDP were used for zirconia (63.8%) and those with silane for silicate-based ceramics (55.9%). Agreement on recommendations ranged between 52% and 100%, with 21/23 reaching an average of 93%. Conclusion: Access to APA influenced clinical decisions and the feasibility of adhesive luting workflows. Adequate APA equipment in dental facilities is essential for quality care. Standardized protocols, training, and education across dental professions are necessary to enhance understanding and proper use of APA. Keywords: adhesive dentistry, airborne particle abrasion, parameter, surface conditioning, bonding, dental restoration

Durch die wachsende Nachfrage nach monolithischen Zirkonoxid-Restaurationen wächst der Anspruch an die Veredelungstechniken. Die stetige Weiterentwicklung des Gerüstmaterials schafft neue Möglichkeiten der Finalisierung. So lassen sich sowohl einige Vorteile als auch neue Herausforderungen durch das Mikrolayering-System beobachten. Die Datenlage ist derzeit noch begrenzt und ein Vergleich der verschiedenen Massen hat noch nicht stattgefunden. Eine Einteilung hinsichtlich verfahrenstechnischer und werkstoffkundlicher Aspekte verschafft einen Überblick. Keywords: Mikrolayering, Minimalverblendung, Beschichtung, Veredelung, Zirkonoxid

Aim: To evaluate the fracture load and type of failure of two different monolithic restorative materials bonded to standardized titanium bases and fabricated by two different procedures regarding the bonding interface. Materials and methods: All screw-retained implant crown specimens (n = 40), subjected to fatigue by thermomechanical loading, differed in the restorative material (lithium disilicate [LDS] or polymer-infiltrated ceramic network [PICN], referred to as ‘hybrid ceramic’ [HYC]) and the interface type between the restorative material and the titanium base abutment (prefabricated ex-factory or produced during a CAM-milling procedure). This resulted in the following groups (n = 10/group): 1) LDS-M: lithium disilicate crown with a CAM-milled interface; 2) LDS-P: lithium disilicate crown with a prefabricated interface; 3) HYC-M: PICN crown with a CAM-milled interface; and 4) HYC-P: PICN crown with a prefabricated interface. Aged specimens underwent static fracture load testing. The load (N) at which the initial crack occurred was denoted as Finitial, and the maximal load (N) at which the restorations fractured as Fmax. All specimens were examined under a stereomicroscope to determine the failure mode. Results: The median Finitial values were 180 N for LDS-M, 343 N for LDS-P, 340 N for HYC-M, and 190 N for HYC-P. The median Fmax values were 1822 N for LDS-M, 2039 N for LDS-P, 1454 N for HYC-M, and 1581 N for HYC-P. The intergroup differences were significant for Finitial (KW: P = 0.0042) and for Fmax (KW: P = 0.0010). The failure types also showed differences between the restorative groups. Conclusions: The choice of restorative material had a stronger influence on the fracture load than the abutment interface workflow. Lithium disilicate showed the highest load for initial crack appearance (Finitial) and for complete fracture of the restoration (Fmax). Keywords: lithium disilicate, dental materials, polymer-infiltrated ceramic network, thermomechanical aging, fracture load, failure mode, prosthetic dentistry, restorative material, abutment interface

Purpose: To evaluate the minimum ceramic thickness needed to increase the lightness by one value by means of glass-ceramic restorations, as perceived by dental technicians, dentists, and laypersons. Materials and Methods: A total of 15 assessment pairs (= reference and test sample) were formed using glass-ceramic blocks in four different colors. Each assessment pair was comprised of two underground blocks differing by one value of lightness. On top of the underground blocks, glass-ceramic platelets were cemented in 5 different thicknesses (0.1 to 0.5 mm) in the same color as the reference. Dental technicians, dentists, and laypersons (n = 41/group) were asked to determine the presence of a color difference between the two samples under standardized light conditions. The threshold ceramic thickness was defined as the thickness at which ≥ 50% of the evaluators were not able to perceive a difference within an assessment pair. The thresholds were analyzed, and groups were compared by applying chi-square test (P < .05). Results: The majority of dentists and dental technicians (> 50%) detected a lightness difference between test and reference samples up to a ceramic thickness of 0.5 mm. The majority of laypersons (≥ 50%) did not perceive lightness differences with ceramic thicknesses of 0.5 mm. If separated by the different color changes, the threshold ceramic thickness started at 0.4 mm and varied within the groups of evaluators and the lightness of the assessed color. Conclusions: A considerable number of evaluators perceived a lightness difference when minimally invasive ceramic restorations of 0.5-mm thickness were applied. The threshold ceramic thickness, however, was reduced when the lightness of the substrate was lower.

Begleitend zu der stetig steigenden Nachfrage nach monolithischen Zirkonoxid-Restaurationen, drängt die Methode der minimalen Verblendung und Bemalung zunehmend in den Vordergrund. Das sogenannte Mikrolayering oder die sogenannten 3-D-Massen gelten als Schlüsselbegriffe dieser Konzepte. Die momentane wissenschaftliche Datenlage zu diesen Systemen, bestehend aus Mal-, Textur- und Glasurmassen, ist unzureichend. Zahlreiche Anwenderbeispiele spiegeln positive Bewertungen hinsichtlich Ästhetik, Reproduzierbarkeit und Effizienz wider. Keywords: Mikrolayering, 3-D-Massen, Zirkonoxid, Pastenkeramik, Minimalschichtung