Libri correalti

Purpose: To evaluate the behavior of hybrid abutment crowns fabricated from monolithic lithium disilicate ceramic (LDC) and to compare the influence of different in vitro artificial aging protocols. Materials and Methods: A total of 32 monolithic hybrid abutment crowns of monolithic LDC were fabricated. Of these, 24 were artificially aged using three different protocols up to a 20 year simulation (1.2 × 10⁶, 2.4 × 10⁶, 4.8 × 10⁶ chewing cycles, thermocycling), a control group underwent no artificial aging (n = 8, N = 32). Load-to-failure tests were conducted for all specimens, and failure values were compared (P < .05). Results: All specimens passed in vitro aging. Mean failure load values between 532.6 and 562.8 N were found but did neither differ significantly among the test groups nor from the control group. Conclusions: Within the limitations of this in vitro pilot study, hybrid abutment crowns manufactured from monolithic LDC seem to offer appropriate long-lasting mechanical stability over a simulation period up to 20 years. The failure values and complication pattern seem to be independent of several aging protocols in this test set-up.

Osteoarthritis of the temporomandibular joint (TMJ) is a degenerative joint disease that leads to morphological and functional changes in the TMJ. Clinically, it can be associated with crepitation, pain, and functional limitations. The following article describes a patient case who presented with the above. First, the function-specific diagnostic cascade is explained. Based on these examinations, the diagnosis of temporomandibular disorder (TMD) with the components of occlusopathy, myopathy, and arthropathy was performed. Initially, a conservative treatment approach was chosen, which led to pain elimination. A follow-up examination 3 months later revealed a severely altered occlusion with only one single static occlusal contact, necessitating further measures. The focus was on slowing down the degenerative changes in the TMJ, eliminating the inflammation of the left TMJ, and restoring functional occlusion. These treatment goals were achieved only through the additional use of a tooth-colored CAD/CAM occlusal splint. For this purpose, the jaw relation was digitally transferred from the conventional centric splint to the CAD/CAM occlusal splint. The patient case is an example of a combined digital-conservative treatment approach for complex TMD cases. Parole chiave: osteoarthritis, TMJ effusion, function-specific diagnostic cascade, conservative treatment, tooth-colored fully anatomical CAD/CAM occlusal splint, digital transfer of the jaw relation

Die additive Multimaterialfertigung hat das Potenzial, goldhaltige Teleskopkronen kosteneffizient ­herzustellen und damit dem Fachkräftemangel und steigenden Goldpreisen entgegenzuwirken. Neue Prozesse werden entwickelt, wobei erste Tests zur Prozessqualifizierung vielversprechende Ergebnisse zeigen. Parole chiave: 3-D-Druck, digitale Fertigung, Multimaterial, Teleskopkronen, Biokompatibilität

Mithilfe der additiven Multimaterialfertigung können aus verschiedenen Legierungen bestehende Teile in digitalen Prozessketten gefertigt werden. In dem Beitrag wird die Anwendbarkeit der Fertigungstechnologie für die Dentalbranche anhand zweier Applikationen gezeigt und bewertet. Parole chiave: 3-D-Druck, additive Fertigung, Multimaterialfertigung, Doppelkronen, Implantate

Pronounced defects of the dental hard tissue can be caused by different etiologic factors. Most frequently, they are associated with changes in the vertical dimension of occlusion (VDO), which may also influence the condylar positions. These defects can lead to irreversible loss of tooth structure and have dramatic functional and esthetic consequences, often requiring complex rehabilitation. In this situation, CAD/CAM-fabricated occlusal splints made of tooth-colored polycarbonate are a proven and safe pretreatment approach in terms of esthetics and function. Rebuilding lost dental hard tissue to restore the occlusion and VDO to an adequate condylar position is a prerequisite for any sustainable and functional rehabilitation. In the future, digital systems will support this complex process, customizing it and making it simpler and more precise. The DMD-System (Ignident) provides patient-specific jaw movement data to optimize the CAD/CAM workflow. This system allows real movement patterns to be digitized and analyzed for functional and potential therapeutic purposes, integrating them into the dental and laboratory workflow. In the present case, the familiar tooth-colored CAD/CAM-fabricated occlusal splint is supplemented by digital centric jaw relation recording and individual movement data. Parole chiave: vertical dimension of occlusion (VDO), instrumental functional analysis, maximum intercuspation (MI), maximal intercuspal position (MIP), centric condylar position (CCP), centric relation (CR), tooth-colored occlusal splint, digital workflow

Aim: The CAM 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 polymethyl methacrylate (Telio CAD) were examined, representing these different material classes. For each material, 12 specimens (n = 12) were fabricated in five thicknesses (0.4, 0.7, 1.0, 1.3, and 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 was determined. Results: Logarithmic regression curves showed the best R2 approximation (Cerasmart: R2 = 0.994; Vita Enamic: R2 = 0.978; Lava Ultimate: R2 = 0.997; Telio CAD: R2 = 0.997) to the light transmission values. Conclusions: The results of the present study indicate that the translucency of resin-based materials can be calculated using a mathematic approach to estimate their optical behavior. Cerasmart, Lava Ultimate, Vita Enamic, and Telio CAD 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. Parole chiave: hybrid materials, PMMA, polymer-infiltrated ceramic network, resin nano-ceramics, translucency, translucency equation, mathematic analysis, CAD/CAM, digital workflow

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 Parole chiave: 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. Parole chiave: Silikatkeramik, Lithiumdisilikat, additive Fertigung, 3-D-Druck, monolithische zahnfarbene Restaurationen