Wenz, Hans-Jürgen

Obwohl sich die Genauigkeit und die Indikationsbreite der digitalen Abformung beständig weiterentwickeln, ist die konventionelle, analoge Abformung weiterhin ein zentraler Bestandteil in der zahnärztlichen Praxis, und das wird – auch unter ökonomischen Aspekten – noch viele Jahre lang so bleiben. Gerade die Auseinandersetzung mit der digitalen Technik hat nochmals verdeutlicht, dass für die korrekte und präzise Erfassung einer Präparation diese vollständig und nicht kontaminiert dargestellt werden muss. Das unterstreicht die große Bedeutung der parodontalen Vorbehandlung und des Gewebsmanagements im Rahmen des klinischen Prozesses der Abformung. Elastomere Abformmaterialien wie A-Silikone und Polyether erfüllen alle notwendigen Anforderungen, unterscheiden sich aber im Detail, was bei ihrem Einsatz zu berücksichtigen ist. Diese Unterschiede zeigen sich auch bei der Kompatibilität zu blutstillenden Mitteln, welche bei Polyether einen deutlichen Einfluss auf die Abbindung im Kontaktbereich haben. Meist wird in der Literatur zum Thema Abformung eine bestimmte Technik als überlegen eingestuft. Für die Autoren des vorliegenden Beitrags stehen die Doppelmisch- und die Korrekturabformung als die am weitesten verbreiteten Techniken in der klinischen Anwendung gleichberechtigt nebeneinander, wobei es indikationsspezifische Vorteile für beide Verfahren gibt. Wichtig ist, die jeweilige Technik konsequent – unter Kenntnis ihrer Vor- und Nachteile – auszuführen. Der Beitrag soll dafür Hinweise geben, kann allerdings wegen des begrenzten Platzes nicht auf alle Aspekte eingehen. Keywords: Doppelmischabformung, Korrekturabformung, Abformmaterialien, Retraktionsfäden, Blutstillung

Aim: One of the most challenging tasks in daily practice when it comes to defining treatment goals and how to attain them is the communication with the patient and the self-reflection of the treating dentist. Failures due to miscommunication are common, especially in esthetic dentistry. The purpose of this study was to evaluate the influence of dental education on students' and dentists' judgment of patients' dental appearance. Materials and methods: Based on internationally accepted guidelines about dental esthetics, a questionnaire was developed to measure "dental appearance" (QDA). Eleven items defined a QDA score (0 = "absolutely dissatisfied", 100 = "absolutely satisfied"). The QDA was completed by 29 patients (21 women, 8 men) before and after a complete oral rehabilitation, including restoration of the anterior teeth. Overall, 95 students (1st, 5th, and 10th Semester) and 30 dentists evaluated the patients' esthetics before and after rehabilitation on a visual analog scale (VAS; 0 = "absolutely unesthetic", 100 = "absolutely esthetic"). Results: Students and dentists alike judged a significant esthetic improvement after treatment (P ≤ 0.0001). Significant differences could be found when comparing the students' and dentists' judgment and the patients' self-evaluation (P ≤ 0.05). Conclusion: Since it seems that students judge dental appearance differently from patients' self-assessment, teaching esthetic rules at university should incorporate the aspect of patient feedback in order to avoid misconceptions.

Deutscher Ärzte-Verlag, Köln 2015, 13. aktualisierte Auflage, ISBN 978–3–7691–3569–5, 417 Seiten, mit 304 Abbildungen in 401 Einzeldarstellungen, 49,99 Euro

Ziel: In der täglichen Praxis ist die Kommunikation mit dem Patienten und die Selbstreflexion des behandelnden Zahnarztes eine besondere Herausforderung, wenn Behandlungsziele und -modalitäten festgelegt werden. Misserfolge aufgrund von missverständlicher Kommunikation sind häufig, vor allem in der ästhetischen Zahnmedizin. In dieser Studie wurde untersucht, welchen Einfluss die zahnärztliche Ausbildung von Studierenden und Zahnärzten auf ihre ästhetische Bewertung des dentalen Erscheinungsbilds der Patienten hat. Material und Methode: Auf der Grundlage international anerkannter Leitlinien zur dentalen Ästhetik wurde ein Fragebogen zur Bewertung des "Dentalen Erscheinungsbilds" (FDE) entwickelt. 11 Items definierten einen FDE-Score (0 = "vollkommen unzufrieden", 100 = "vollkommen zufrieden"). Der FDE wurde von 29 Patienten (21 Frauen, acht Männern) vor und nach einer vollständigen oralen Rehabilitation mit Restauration der Frontzähne ausgefüllt. Insgesamt 95 Zahnmedizinstudierende (1., 5. und 10. Semester) und 30 Zahnärzte bewerteten die Ästhetik der Patienten vor und nach der Rehabilitation auf einer visuellen Analogskala (0 = "vollkommen unästhetisch", 100 = "vollkommen ästhetisch"). Ergebnisse: Studierende und Zahnärzte kamen gleichermaßen zu der Bewertung, dass die Ästhetik nach der Behandlung signifikant verbessert war (p ≤ 0,0001). Signifikante Unterschiede fanden sich beim Vergleich der Bewertungen der Studierenden und Zahnärzte mit der Selbstbewertung der Patienten (p ≤ 0,05). Schlussfolgerung: Da Studierende das dentale Erscheinungsbild offenbar anders bewerten als die Patienten in der Selbstbewertung, sollte bei der Vermittlung ästhetischer Regeln an der Universität auch der Aspekt der Abstimmung mit dem Patienten berücksichtigt werden, um Missverständnissen vorzubeugen.

Purpose: The purpose of this study was to compare patients' and dentists' perception of dental appearance. Materials and Methods: Based on internationally accepted guidelines about dental esthetics, a questionnaire was developed to measure "dental appearance" (QDA). Eleven items defined a QDA score (0 = "absolutely dissatisfied" to 100 = "absolutely satisfied"). The QDA was completed by 29 patients (21 women, 8 men) before and after a complete oral rehabilitation that included restoration of the maxillary anterior teeth. Overall, 94 dentists from four countries (Germany, the United Kingdom, China, and Switzerland) evaluated the esthetics before and after rehabilitation on a visual analog scale (VAS: 0 = "absolutely unesthetic" to 100 = "absolutely esthetic"). Results: Patients and dentists of all countries found a significant esthetic improvement after treatment (P ≤ .0001). Significant differences could be found when comparing the evaluation of the dentists from the various countries among one another and with the patients' self-evaluation (P ≤ .05). With the exception of the professional rating of the initial situation, no gender-related differences could be found in any of the test groups. Conclusions: In daily practice, it seems of utmost importance for dentists to incorporate the patients' feedback in order to avoid esthetic treatment failures.

Objectives: Oral cancer is a considerable health problem with more than 10,000 new diagnosed cases each year in Germany. Comparably little is known about the knowledge of the public on oral cancer and its possible relationship to socioeconomic parameters. It was the aim of this project to investigate the knowledge about risk factors of oral cancer in the State of Schleswig-Holstein in Germany. Methods: A well-known German polling firm formulated a telephone-based survey based on a standardized questionnaire. This survey was validated by a pretest and a representative survey (n=1000) via computer-aided telephone interview (CATI) was carried out by the polling firm within the public of Schleswig-Holstein, Germany. Descriptive statistics of demographic variables of the sample and responses to the questionnaire were reported by means of counts and percentages. Knowledge of the risk factors was further classified according to different socioeconomic categories and their subgroups. All analyses were done with the SPSS for Windows 15.0 software. Results: More than 70% of the sample of the public knew use of tobacco and a prior oral cancer lesion as risk factors. Other risk factors, such as the consumption of alcohol and older age were only identified by around 50% of the sample. The detailed analysis revealed a relationship between a low level of knowledge and socioeconomic factors such as older age, low level of education, occupations such as e.g. blue collar worker and a low income. Conclusions: The survey illustrated that the public of Schleswig-Holstein is not well-informed about the risk factors of oral cancer. In addition, the low level of knowledge was associated with a low level of certain socioeconomic factors. Improved targeted health education and health promotion strategies for the public are recommended to improve early detection and ultimately the prognosis of oral cancer. Keywords: oral cancer, public, risk factors, knowledge, Germany

In dieser In-vitro-Studie wurden die Haltekräfte von Doppelkronen mit Spielpassung und zusätzlichem Haltelement (TK-Snap®) über insgesamt 10.000 Fügezyklen untersucht. Die Kronen wurden aus einer Kobalt-Chrom-Legierung, einer Gold-Platin-Legierung und aus Titan hergestellt. Für die Doppelkronen jeder Gruppe wurde ein klinisch akzeptables Langzeitverhalten der Haltekräfte beobachtet. Diejenige Doppelkrone je Legierungstyp, die am Ende der Versuchsreihe die niedrigsten Haltekräfte aufwies, wurde mit einem neuen Halteelement versehen und nochmals 10.000 Fügezyklen ausgesetzt. Durch den Austausch des Halteelements konnte in jedem Fall nicht nur die Wiederherstellung der initialen, sondern auch der langfristig wirksamen Haltekräfte erreicht werden. Keywords: Doppelkronen, Halteelement, herausnehmbarer Zahnersatz, Marburger Doppelkrone, Spielpassung, Verschleißverhalten

Purpose: The purpose of this in-vitro study was to evaluate the resin bond strength to pre-etched lithium disilicate ceramic using different cleaning methods after two contamination modes (saliva or saliva and silicone). Materials and Methods: Plexiglas tubes filled with composite resin (MultiCore Flow) were bonded to etched and silanized ceramic disks made of lithium disilicate ceramic (IPS e.max Press) using a luting resin (Multilink Automix). Either etched or unetched ceramic surfaces were contaminated with saliva or with saliva followed by a disclosing silicone. Groups of 16 specimens each were bonded after pretreatment using 4 surface cleaning agents (37% phosphoric acid, 5% hydrofluoric acid, 96% isopropanol, air polishing device with sodium bicarbonate) in different combinations. Before measuring tensile bond strength, specimens were stored for 3 or 150 days with thermocycling. Results: After 150 days of storage, etching of saliva-contaminated surfaces with 5% hydrofluoric acid and/or 37% phosphoric acid provided statistically significantly higher bond strengths (37.9 to 49.5 MPa) than the other cleaning methods (1.7 to 15.5 MPa). After saliva and silicone contamination, etching with 5% hydrofluoric acid provided statistically significantly higher bond strengths (44.5 to 50.3 MPa) than all other cleaning methods (0.3 to 13.5 MPa). Conclusion: Ceramic cleaning methods after try-in procedures have a significant influence on the resin bond strength and are dependent on the type of contamination. Re-etching lithium disilicate ceramic with 5% hydrofluoric acid is most effective in removing contamination with saliva and/or a silicone disclosing medium. Keywords: lithium disilicate ceramic, cleaning, contamination, tensile bond strength

Purpose: The aim of this study was to investigate the deviations of the implant positions of both impressions and casts using different impression materials and techniques. Furthermore, the existence of a correlation between the deviations of the impression and those of the cast was investigated. Materials and Methods: A reference model was fabricated with 5 Frialit-2 implants parallel to each other. In a standardized experimental setting, 5 stone casts were produced with 5 different techniques using polyether (A) or polyvinyl siloxane (B through E). In 3 groups, a direct technique was used with a medium-viscosity material or a putty-tray material in combination with a light-viscosity syringe material (A to C). In 2 groups, an indirect technique (either 1-step [group D] or 2-step [group E] was used with a putty-tray material in combination with a light-viscosity syringe material. The center-to-center distances were measured for impressions and casts in the horizontal plane using a computer-aided microscope, and the relative and absolute deviations compared to the reference model were calculated. Analysis of variance followed by the post-hoc Scheffé test (parametric data) or the Kruskal-Wallis test followed by pair-wise Mann-Whitney tests (nonparametric data) were used for statistical analyses. Deviations of impressions were compared with their respective casts using paired t tests and the Pearson correlation coefficient. Results: No significant differences for the relative deviations were found for impressions (-5 to -8 µm) or casts (+7 to +16 µm). Group E produced significantly higher absolute deviations for impressions (38 µm) and casts (39 µm) compared to the other groups (11 to 18 µm and 17 to 23 µm, respectively). A significant correlation between deviation of the impression and its respective cast was found for every group (r = 0.40 to 0.80) except group D. Conclusions: The distortions in the horizontal plane of the casts obtained from the impression techniques of groups A to D would probably not affect the clinical fit of implant-retained superstructures. Because of the high variation of deviations (-113 to +124 µm), the 2-step technique cannot be recommended. The method to measure both impression and cast provided a better understanding of how inaccuracies are caused. Keywords: dental implants, impression materials, impression technique, transfer coping