Effect of Model Resin and Shaft Taper on the Trueness and Fit of Additively Manufactured Removable Dies in Narrow Ridge Models.

Effect of model resin and shaft taper angle on the trueness and fit of additively manufactured removable dies in narrow ridge casts Purpose. To evaluate how model resin and shaft taper affect the trueness and fit of additively manufactured removable dies in narrow ridge casts. MATERIAL AND METHODS: A typodont model with a prepared mandibular molar was scanned to design virtual dies with different shaft tapers (0-degree (straight), 5-degree, and 10-degree tapered). Fifteen dies and one hollowed cast per taper were additively manufactured from two resins (G-PRINT 3D Model, GP and DentaMODEL, DM). Dies and casts were digitized to evaluate their trueness (root mean square (RMS)). The fit of the dies was evaluated with crown portion's RMS when seated in the cast and with distance deviations. Kruskal-Wallis and Mann-Whitney U tests were used to analyze data (α =.05). RESULTS: GP dies had lower overall, root, and base RMS, while DM dies had lower crown RMS (P≤.016). Straight dies had the highest overall, root, and base RMS within GP (P≤.030). Ten-degree dies had the lowest overall and base RMS, lower crown RMS than straight, and lower root RMS than 5-degree dies within DM (P≤.047). When the dies were seated, GP had lower crown portion RMS within 5- and 10-degree dies, and 5-degree dies had the highest RMS within DM (P≤.003). GP had lower distance deviations within 5- and 10-degree dies. Five-degree dies had the highest deviations within DM (P≤.049). CONCLUSIONS: GP dies mostly had higher trueness and better fit. Straight dies mostly had lower trueness within GP. Ten-degree taper mostly led to higher trueness within DM. The shaft taper affected DM dies' fit.

[Sustainable dentistry - Part II: Sustainable workplace and waste management]. / Die nachhaltige Zahnmedizin. Teil 2: Nachhaltigkeit am Arbeitsplatz und in der Abfallreduktion.

This second and final part of the publication on the topic of sustainability in dental practices deals with the so-called workplace management, which describes the work processes and the consumption of energy and materials in the practice itself. Waste management is also addressed, which discusses the path of resources from the practice to disposal and recycling. Finally, an example from materials research is presented using implants.

[Sustainable dentistry - Part I: Sustainability and pre-workplace management]. / Die nachhaltige Zahnmedizin ­ Teil 1: Nachhaltigkeit im Umfeld von Zahnarztpraxen.

Sustainability in dental practices is playing an increasingly important role. External and internal factors have an influence on the emissions of a practice. The external factors include the domains of politics, science, and education. It is eminent that the discussion on the environmental impact in healthcare finds its way into these three domains, as it lays the foundation for behavioural change and thus paves the way for a greener future. The internal factors include practice operations, supply chain, employees, and patients. Overall, the topic of sustainability is hardly prevalent in the dental workplace. This first article of a two-part series highlights how sustainability in dentists' practices and work is influenced by many environmental factors which, taken together, can affect the interplay between the environment and dentistry.