Books

Das in der restaurativen Zahnheilkunde bis zur Mitte des 20. Jahrhunderts vorherrschende Prinzip der Makroretention wurde in der zweiten Hälfte des 20. Jahrhunderts von der Mikroretention sukzessive abgelöst und seit Anfang des 21. Jahrhunderts mehr und mehr verdrängt. Dieser Weg hat sich trotz zahlreicher Rückschläge, Verwerfungen und Irrwege durchgesetzt und alle Disziplinen der Zahnmedizin befruchtet. Ein Zurück zur Makroretention ist zwar nicht auszuschließen, nach aktuellem Wissensstand aber unwahrscheinlich. Die heute realistisch gewordenen Zielsetzungen der frugalen Zahnmedizin, die ohne die Verbreitung adhäsiver Kunststoffe nicht denkbar sind, würden sich bei einer solchen Rückwärtsentwicklung kaum verfolgen lassen. Der vorliegende Zeitzeugenbericht präsentiert einige Meilensteine von den 1970er-Jahren bis heute. Manuskripteingang: 10.05.2024, Manuskriptannahme: 20.06.2024 Keywords: Makroretention, Mikroretention, adhäsive Zahnmedizin, frugale Zahnmedizin, Geschichte der Komposite und der Adhäsive, Amalgam

Purpose: This study aimed to develop a systematic interdental brush set with size distribution based on the passage hole diameter (PHD), addressing existing gaps in size selection criteria for effective interdental cleaning. Materials and Methods: In the first step, an interdental brush set that ascends stepwise according to the PHD value was envisioned. The study was divided into three phases: (i) in-vitro determination of PHD values of a currently existing assortment on the market by 13 calibrated dental professionals, (ii) in-vitro assessment of forces during insertion, and (iii) creation and evaluation of new prototypes for missing or non-matching PHD sizes. Intra- and inter-rater reliability, assessed with the intraclass correlation coefficient (ICC), as well as insertion forces and PHD sizes at all stages were reported. Results: In the existing range, three interdental brushes fitting the desired PHD sizes were initially identified. Mean insertion forces between 0.3 and 1.7 N were documented based on raters’ PHD choices. Two additional rounds of measurements with prototypes adapted in diameter and shape were necessary, particularly for PHD values of 1.4, 2.3 and 2.6. High intra- and inter-rater reliability was observed throughout the study (ICC > 0.95), ensuring consistent evaluations. After three rounds of assessments, a prototype was successfully identified for each targeted PHD value in the systematised set, showcasing reliable sizing and insertion forces. Conclusion: Using a structured approach, a comprehensive interdental brush set was developed with reliable PHD sizing and moderate insertion forces. The verification of size reliability through measurements by dentists represents a novelty in development and underlines the importance of accurate brush size selection for optimal biofilm control. Whether a systematic set based on the PHD value offers added value for clinical practice, and at what intervals, must be demonstrated in further studies. Keywords: interdental brush, systematic set, interdental hygiene

Purpose: This paper describes previously unknown details about the discovery of resin adhesion to acid-etched human enamel.Materials and Methods: A literature review was performed through manual assessments. Primary sources revealing the discovery of resin curing on etched enamel were analyzed considering the research objectives and methodological procedure during that era, including the type of teeth used, preparatory measures, acid-etching process, type of resin and its application, and follow-up observations. Additionally, the political and economic contexts were examined.Results: In 1949, acid etching was found to promote adhesion with acrylic resin, a finding described again in 1955. The 1949 studies utilized nitric acid for enamel etching and the acrylate resin Paladon from the Kulzer company (Germany). Conversely, the 1955 investigations employed phosphoric acid and an unnamed acrylate, likely a self-curing resin supported by Kulzer in the late 1930s. Disparities in the 1949 and 1955 findings can be ascribed to varying objectives and test conditions amidst a turbulent political backdrop, significantly impacting the Kulzer company.Conclusion: The discovery of resin adhesion to acid-etched enamel, approaching its 75th anniversary in 2024, is a landmark in 20th-century adhesive dentistry. Paladon represents a pioneering compound, exemplifying the influence of political, ideological, and economic factors on scientific advancements during that period. Keywords: adhesion of acrylics to acid-etched enamel, history of adhesive dentistry, history of dental acrylics

Purpose: The subgingival area is only reached to a limited extent during home oral hygiene with the aids available to date. The question was investigated whether a newly developed, flattened cross-sectional design of interdental brushes (IDBs) can extend their subgingival reach. Materials and Methods: In part I, the passage-hole diameters (PHD) of IDBs of different sizes and side-bristle lengths, with circular and flattened cross-sections, were compared according to the ISO standard 16409/2016. In part II, handling of flattened IDBs was described based on a case report of a patient with generalised stage 4, grade C periodontitis with locally persistent pockets. Results: Depending on the brush’s size, flattening of IDBs reduced the PHD by 1-18 intervals. IDBs with longer side bristles could thus be inserted into interdental spaces with equal force. This may increase the potential range of IDBs in the vertical dimension. Regular instruction and check-ups are necessary to enable correct handling, as the flattened brushes can only be used in two positions. The observations documented in the case report (duration: 1.5 years) showed that flattened IDBs were associated with reduced signs of inflammation (reduction of pocket depths from 6 to 3 mm, absence of bleeding on probing). Conclusion: IDBs with a flattened cross-sectional design have not been previously described in the literature. It was shown that flattening of IDBs leads to a size-dependent decrease in PHD. Based on a case report, it was hypothesised that the design change of the IDBs could be clinically relevant in the case of persistent deep pockets in narrow interdental spaces. However, this can only be verified or falsified by clinical studies. Keywords: flattened interdental brushes, preventive dentistry, subgingival oral hygiene

Purpose: Newly developed non-invasive methods for replace a missing tooth and closing single-tooth gaps in the poster- ior region using resin composite are presented. Materials and Methods: Four different non-invasive methods and the technical procedures, materials and instruments used are presented in a case series. These include the direct intraoral insertion of composite (with and without individual shaping aids) and indirect restorations, which are fabricated conventionally or digitally and bonded. Results: The case series showed that all four methods can be used to replace single missing teeth in the posterior region, meeting current clinical requirements. Particular attention was paid to the design of the pontics, the dimension of the connector area, firm proximal contacts to the adjacent teeth, hygiene, and appearance of the non-prep bridges (NPBs). The advantages and disadvantages for both the direct and indirect techniques illustrated in this case series were com- pared in detail. Conclusions: Several direct and indirect non-invasive methods for single-tooth replacement are available today. Although the evidence is still limited, there is a potential for frugal dental interventions with NPBs. Further experimental and clinical studies are necessary to demonstrate that they reliably meet quality requirements (including sufficient survival rates), satisfy the criteria of cost-effectiveness (compared to treatment alternatives) and that there is a demand from the population. Keywords: all-composites, cantilever design, gap-closure in the posterior area, non-invasive restorative methods

Einleitung: In diesem Artikel werden die zahnmedizinisch relevanten Ursprünge von Acrylatkunststoffen und Adhäsivtechniken bis 1955 beleuchtet. Dabei finden neben technischen und klinischen Aspekten auch politische Rahmenbedingungen – einschließlich gesundheits- und standespolitischer Art – besondere Berücksichtigung. Material und Methode: Literaturrecherche in digitalen Medien sowie händische Durchsichten. Ergebnisse: Die Pionierarbeiten der Acrylat- und Adhäsionsforschung reichen in die zweite Hälfte des 19. Jahrhunderts und in die erste Hälfte des 20. Jahrhunderts zurück. Sie waren nicht nur von Erfolgen, sondern auch von zahlreichen Rückschlägen begleitet. Eine für die zahnärztliche Prothetik besonders wichtige Ära der extraoral gefertigten Werkstücke lag zwischen 1930 und 1940. Ihr folgte zwischen 1940 und 1950 eine für die Zahnerhaltungskunde bedeutsame Epoche der intraoral verarbeitbaren Materialien. Das Jahr 1949 war der Ausgangspunkt für die kunststoffbasierte adhäsive Zahnheilkunde. In dieses Jahr fällt zum einen die Vermarktung eines – anfangs nicht sehr erfolgreichen – Kunststoff-Sealers auf Glycerophosphorsäurebasis und zum anderen die – zunächst wenig beachtete – Entdeckung, dass Säureätzung von Zahnschmelz (mit Salpetersäure) eine Adhäsionssteigerung zu dünnen Kunststoff-Filmen auf Acrylatbasis bewirkt. Sechs Jahre später (1955) wurde gezeigt, dass sich durch Säureätzung von Zahnschmelz (mit Phosphorsäure) eine Adhäsionsverbesserung auch zu dickeren Kunststoffmassen erreichen lässt. Die Forschungsarbeiten wurden durch die besonderen Umstände in jener Zeit – einschließlich Devisen- und Rohstoffknappheit – vor, während und nach dem Zweiten Weltkrieg beeinflusst. Hinzu kam in Deutschland unter anderem der Standesdualismus zwischen der teilweise stark verfeindeten akademischen Zahnärzte- und der handwerklichen Dentistenschaft, durch den kooperatives Handeln erschwert wurde. Diskussion und Schlussfolgerung: Mit der Einführung dentaler Kunststoffe war unter anderem die Absicht verbunden, ressourcenschonende, kostengünstige und von Patienten gut akzeptierte Materialien und Techniken zur Verfügung zu stellen. Bis Kunststoffe zu Repräsentanten einer heute als "frugale Zahnmedizin" bezeichneten Richtung werden konnten, waren zahlreiche wissenschaftliche Leistungen zu erbringen und gleichzeitig vielerlei zeitbedingte politische Hürden zu überwinden. Einige der vor 1955 gemachten Entdeckungen sind bislang in der Literatur unvollständig oder überhaupt nicht beschrieben. Die Kenntnis dieser Entdeckungen kann zu einem besseren historischen Verständnis der adhäsiven Zahnheilkunde beitragen. Keywords: Geschichte, Haftung von Acrylaten auf Zahnschmelz, adhäsive Zahnheilkunde, dentale Kunststoffe

Purpose: To examine the origins of acrylates and adhesive dentistry up to 1955. Materials and Methods: A search of MEDLINE database and a manual literature search were conducted to find relevant articles. Results: Acrylic acid was discovered in 1843, methacrylic acid in 1865. In 1880, light polymerization of acrylate compounds using glass prisms was introduced. In 1928, polymethyl methacrylate (PMMA) was industrially produced from methyl methacrylate (MMA). In 1930, PMMA moldings that could be adapted under heat and pressure were introduced into dentistry. The process was improved in 1936 by mixing pulverized PMMA and liquid MMA. In 1940, the intraoral polymerization of dental resins using UV light or catalysts was discovered. In the same year, the combined procedure (dual-curing) and addition of inorganic fillers to improve the material properties (precursors of composites) were proposed. Effects on the oxygen inhibition layer and intraoral bonding between several resin portions were also described. In 1942, direct restorations with self-curing resins (combined with a precursory version of cavity sealing) were described. These new resins were marketed in the late 1940s. Intraoral repair of restorations and cementation of crowns and bridges with resins were also described in 1942. In 1949, a glycerophosphoric acid-based sealer was marketed. In the same year, it was discovered that etching of the enamel (with nitric acid) caused an adhesion to thin layers of acrylic-based materials. In 1955, phosphoric acid etching of enamel was shown to improve adhesion. Conclusion: In the first half of the 20th century, important but little or unknown discoveries took place. These discoveries can improve our understanding of how adhesive dentistry evolved. Keywords: history of dental acrylates, history of adhesive dentistry, origins of composites, redox cure, dual cure, photocure, origins of acid etching of enamel, beginnings of acrylic-based cementation of crowns and bridges, beginnings of acrylic-based restorations

Eine Festschrift für Winfried Walther In den vergangenen 40 Jahren hat der Zahnarzt, Hochschullehrer und Forscher Winfried Walther sein berufliches Lebenswerk in den Dienst der Akademie für Zahnärztliche Fortbildung Karlsruhe gestellt. In Würdigung seiner weitreichenden Aktivitäten, die vom "Freigeist des Hinterfragens" geprägt waren und sind, haben 23 seiner Weggefährtinnen und -gefährten ein sehr gut gelungenes Buch verfasst, das in vielerlei Hinsicht eine Sonderstellung in der zahnärztlichen Literatur einnimmt. In allen fächerübergreifenden Kapiteln aus den Kategorien "Akademie", "Universität" und "Praxis" gelingt es den Autoren, den Blick von der scheinbar engen zahnärztlichen Welt in übergeordnete Zusammenhänge dergestalt zu erweitern, dass die Lektüre nicht nur durchgängig höchst informativ ist, sondern geradezu zum Genuss wird.

At present, the most important criterion for the size selection of interdental brushes is the PHD-value (passage hole diameter) according to the ISO standard for interdental brushes ISO 16409:2016. The PHD size range of commercially available products currently lies between 0.6 and 5.2 mm. With the exceptions of special situations, a range between 0.7 and 2.9 mm is sufficient for clinical routine. As most products have longer filaments nowadays, one brush can often be applied for two PHD intervals. Consequently, adequate patient counseling and the individual selection of the appropriate interdental brushes can generally be achieved with an assortment of 12 systematically arranged interdental brush sizes. An application example is the “Heidelberg set” described herein. It is crucial that the correct choice of size is based upon continuously rising PHD-values, and not upon parameters such as stem size, outer diameter of filaments, or similar, as these do not allow for a reliable conclusion regarding the interdental passage. The usage of ISO sizes is also not recommendable due to their insufficient size differentiation. (Quintessence Int 2021;52: 176–186; doi: 10.3290/j.qi.b872241; Revised from an article originally published (in German) in Parodontologie 2020;31(1)37–49) Keywords: Heidelberg-Set, interdental brush, interdental hygiene, passage hole diameter, mechanical plaque control

Neue Methoden zum Schließen von Einzelzahnlücken mittels direkt eingebrachter, gussmetall-, keramik- und glasfaserfreier Kompositrestaurationen lassen sich in 5 Kategorien einteilen. Bei den Kategorien I und II handelt es sich um Zahnverbreiterungen bzw. -anhänger bis Prämolarenbreite. Bei den im Folgenden beschriebenen Kategorien III bis V geht es um das Schließen von Einzelzahn-Schaltlücken bis Molarenbreite und um das Vorgehen bei Freiendsituationen (direkte Freiendanhänger). Es wird herausgearbeitet, dass diese Optionen das Spektrum des Lückenmanagements im Sinne frugaler Innovationen deutlich vergrößern können. Keywords: Blockverbindung, direkte Restaurationsverfahren, direkte Freiendanhänger, Komposit-Indikationserweiterung, Lückenmanagement, Lückenmonitoring, Schaltlückenschluss mit Komposit, Zahnverbreiterung, Zahnanhänger