Books

Aim: The computer-aided manufacture of esthetically pleasing monolithic dental restorations presents with specific challenges. One vital parameter to consider is the translucency of the materials. Previous studies have proven a correlation between translucency and material thickness for various all-ceramic materials. The aim of the present study was to assess and define the relationship between thickness and translucency in modern resin-based restorative materials. Materials and methods Specimens fabricated from two resin nano ceramics (Cerasmart, Lava Ultimate), a polymer-infiltrated ceramic network (Vita Enamic), and a polymethylmethacrylate (TelioCAD) were examined, representing these different material classes. For each material, 12 specimens (n=12) were fabricated in five thicknesses (0.4 mm, 0.7 mm, 1.0 mm, 1.3 mm, 1.6 mm; N=240). The translucency was measured with a spectrophotometer. The total light transmittance for each specimen was calculated applying specialized software. Regression curves were fitted to the results and their coefficient of determination (R²) fit determined. Results Logarithmic regression curves showed the best R² approximation (Cerasmart, R² = 0.994; Vita Enamic, R² = 0.978; Lava Ultimate, R² = 0.997; TelioCAD, R² = 0.997) to the light transmission values. Conclusion The results of this study indicate that the translucency of resin-based materials can be calculated using a mathematical approach to estimate their optical behavior. Cerasmart, Lava Ultimate, Vita Enamic, and TelioCAD exhibit a logarithmic relationship between material thickness and translucency. By determining material-specific coefficients for this logarithmic function, the resulting translucency can be computed for any given material thickness. Keywords: CAD-CAM, digital workflow, hybrid materials, mathematical analysis, PMMA, polymer infiltrated ceramic network, resin nano ceramics, translucency, translucency equation

Ziel dieses Artikels ist die Darstellung der unterschiedlichen Indikationen und des Herstellungsprozesses individueller CAD/CAM-gefertigter Gingivaformer und korrespondierender Abformpfosten aus PEEK anhand verschiedener Fallbeispiele. Individuelle Gingivaformer und korrespondierende Abformpfosten können sowohl präoperativ nach geführter Implantatplanung mittels DVT-Datensatz (Dicom-Daten) und digitaler Abformung (STL-Daten) als auch post implantationem nach intraoperativer digitaler Registrierung der Implantatpositionen gefertigt und eingesetzt werden. Mithilfe individueller Gingivaformer können das Weichgewebe und das Emergenzprofil ohne aktiven Druck ausgeformt werden. Dies führt sowohl bei der Sofortimplantation als auch bei der Implantatfreilegung zu einer deutlichen Verbesserung des funktionellen und ästhetischen Endergebnisses. Durch den Einsatz individueller Gingivaformer und korrespondierender Abformpfosten kann ein aufwendiges evtl. schrittweises Ausformen der Weichgewebe unter aktivem Druck mittels Implantatsuprarekonstruktion umgangen werden. Manuskripteingang: 19.05.2022, Annahme: 18.07.2022 Keywords: ästhetische Implantologie, Weichgewebeausformung, individuelle Gingivaformer, individuelle Abformpfosten, PEEK

Purpose: To evaluate the shear bond strength (SBS) of different digital veneering techniques for zirconia and to critically discuss its suitability for application in single-implant prosthetics. Materials and methods: A total of 112 square-shaped zirconia specimens were provided with four different veneering materials (n = 28 per group): a glass-ceramic (group GLA), a feldspathic ceramic (group FEL), a polymer-infiltrated ceramic network (group PIC), and a resin nanoceramic (group RNC). Discs in group GLA were sintered onto the core material, whereas all other specimens were adhesively connected. In each group, 14 specimens (GLA0, FEL0, PIC0, RNC0) were subjected to SBS testing before thermocycling, and the other 14 (GLA1, FEL1, PIC1, RNC1) were tested after thermocycling (10,000 cycles). Data were analyzed by applying SPSS software (P < .05). The surfaces and fracture patterns of the specimens were examined using scanning electron microscopy (SEM). Results: Mean SBS values ranged from 14.09 ± 3.87 MPa (RNC1) to 40.82 ± 4.91 MPa (GLA0). Group GLA presented higher values than all other groups (P < .001). Groups FEL, PIC, and RNC showed no statistically significant differences between them. SBS decreased after thermocycling, but no significant impact was found. Every group exhibited a characteristic failure mode. Conclusion: All digital veneering techniques sufficed to present clinically acceptable SBS values and might be viable alternatives in implant prosthetics. However, some have yet to demonstrate their long-term clinical suitability. At present, lithium disilicate-veneered zirconia abutments and monolithic lithium disilicate hybrid abutment crowns seem to present a proven and reliable restorative option.

Purpose: To assess whether material choice for the prosthetic component of an implant restoration influences the failure mode in case of occlusal overload in monolithic restorations fabricated from high-strength ceramics on titanium implants. Materials and Methods: Within this pilot study, finite element analysis (FEA) was conducted to simulate stress and deformation of implant-supported crowns fabricated from lithium disilicate (LiS2) and zirconia (3Y-TZP). Additionally, an in vitro load-to-failure test was conducted using two specimens per group to evaluate the failure mode and to confirm the findings from the FEA. Results/ Conclusion: FEA revealed stress areas at the palatal cervical areas of the crowns. In the load-to-failure test, both LiS2 hybrid abutment crowns fractured (410 N and 510 N) before plastic deformation of the metal implant components could be detected. The 3Y-TZP monolithic hybrid abutment crowns did not fracture until the tests were interrupted at 646-N and 690-N occlusal force, when plastic deformation of the metal implant components was visually observed.

Restaurationen aus Lithiumdisilikat wurden bisher entweder per analoger Presstechnik oder über die digitale subtraktive Bearbeitung mithilfe von CNC-Schleifmaschinen hergestellt. Auf der IDS 2021 stellte die Fa. Lithoz (Wien, Österreich) die additive Fertigung mithilfe der Lithoz LCM-Technologie vor. Anhand einer Eckzahnkrone und vier Seitenzahnkronen wird gezeigt, wie Restaurationen aus Lithiumdisilikat additiv gefertigt werden können, das Vorgehen wird außerdem mit der subtraktiven Herstellung verglichen. Keywords: Silikatkeramik, Lithiumdisilikat, additive Fertigung, 3-D-Druck, monolithische zahnfarbene Restaurationen

Ectodermal dysplasia (ED) is one of the congenitally syndromic diseases with dental anomalies. This syndrome manifests in various forms and usually requires early restorative therapy to restore esthetics and function in young patients. The restorative approaches vary greatly and range from minimally invasive shape corrections using composite build-ups and removable partial or complete dental prostheses, to implantologic solutions, always based on the syndromic expression, the age of the patient, the residual growth, as well as the dentition itself. The present case report presents an innovative prosthetic management of a young patient suffering from ED with permanent tooth aplasia and persistent primary teeth using maxillomandibular individually veneered tooth-colored CAD/CAM polycarbonate splints. The CAD phase has been significantly improved by including the analysis of 3D face scans. This advanced technical development makes it possible to avoid any time-consuming try-in and start directly with the splint production, ensuring a much faster complete rehabilitation and support for the young patient. Keywords: CAD/CAM workflow, case-report/series, complex diseases, ectodermal dysplasia, overdenture, polycarbonate splint, prosthetic rehabilitation, restorative dentistry

Der dreidimensionale Aufbau der Zähne bestimmt seit einiger Zeit das Restaurationsdesign, was wiederum Einfluss auf die Materialzusammensetzung der Versorgungen hat. Der Beitrag gibt einen Überblick über die Materialentwicklung in Abhängigkeit von der Bearbeitungsweise, berichtet über Innovationen und zeigt das künftige Potenzial neuer Technologien auf. Keywords: Zirkonoxid, 3-D-Druck, künstliche Intelligenz, Transluzenz, Opazität

Aim: To investigate retentive forces (RFs) of CAD/CAM-milled and conventionally cast secondary crowns (SCs) after artificial aging in an in vitro study. Materials and methods: Forty artificial premolars were manufactured and provided with 40 primary crowns (PCs) milled from a high noble metal alloy. SCs were fabricated from the same alloy. Ten SCs were produced with the help of a tactile scanning method (group A), 10 with the help of a photo-optical scan (spray; group B), 10 with the help of a photo-optical scan (acrylic dye; group C), and 10 using a conventional casting technique (group D). Cycles of separation were performed and RFs were measured at baseline and after 5,000 and 10,000 cycles. Surfaces were examined under a scanning electron microscope (SEM). Statistical analysis was conducted at a significance level of P ≤ 0.05. Results: Group D showed the highest median RFs with respective interquartile ranges (IQRs) – baseline: 7.0(2.5) N; 5,000 cycles: 5.5(2.0) N; 10,000 cycles: 5.4(1.5) N compared with groups A, B, and C – baseline: 5.2(8.4)/3.4(11.3)/1.3(1.5) N; 5,000 cycles: 1.8(0.8)/2.1(1.7)/1.0(1.3) N; 10,000 cycles: 1.9(1.6)/2.4(2.5)/1.0(1.4) N, respectively. In contrast to groups A, B, and C, group D did not gain RF when RF values were compared after 5,000 and 10,000 cycles. The loss of RF between baseline (7.0 N) and after 10,000 cycles (5.4 N) was significant only for group D (P = 0.007), but not for groups A, B, and C. Conclusion: Both CAD/CAM-milled and conventionally cast SCs from a high noble metal alloy can provide sufficient RF after 10,000 cycles of artificial aging. However, groups A, B, and C showed constantly lower RF values compared with group D. Keywords: CAD/CAM, artificial aging, double crowns, telescopic crowns, retentive force, removable dental prosthesis, high noble metal alloy, gold

VarseoSmile Crown plus ist das weltweit erste keramisch gefüllte Hybridmaterial für den 3-D-Druck permanenter Einzelkronen, Inlays, Onlays und Veneers. In einer Reihe prä-klinischer wissenschaftlicher Studien wurden verschiedenste Aspekte untersucht. In diesem Bericht werden die Ergebnisse zum Dezementierungsverhalten additiv gefertigter Kronen aus VarseoSmile Crown plus und die Ergebnisse zur initialen Bruchfestigkeit beschrieben. Keywords: 3-Druck, definitiver Zahnersatz, Kompositmaterial, Dezementierung, Bruchfestigkeit