Here, Ed Littlewood, Marketing Manager at Renishaw’s Medical and Dental Products Division discusses the benefits of a digital workflow for dental manufacturers and laboratories.
Dental laboratories are no strangers to digital manufacturing. For more than a decade they have been scanning dental models and using specialised software to design crown and bridge restorations. Milling, a process by which material is removed from a workpiece, has traditionally been the preferred means of production. Now alternative manufacturing methods, including a plethora of 3D printing technologies, are becoming more prevalent as the industry moves towards fully digital workflows.
Computer-aided-design
Computer-aided design (CAD) is the keystone of digital dentistry. This allows manufacturers to create more precise dental implants, bridges and structures with less manual input than if a traditional manufacturing process was to be used. During the process, dentists take an impression of their patient's teeth, which is then sent to the dental laboratory where the impression is scanned to create a digital copy of the mould. A physical model can then be manufactured using traditional milling techniques or using more contemporary methods such as 3D printing.
Using a digital file, rather than an actual impression, helps the lab minimise the risk of errors as digital files can be reviewed and revised before the final product is made. The majority of modern dental scanners create a digital file by using either fringe projection technology or laser scanning, to create an accurate reproduction of the impression. This allows for a more precise final result.
In the future, we can expect patient impressions to phase out completely and intraoral scanners (IOS) to become more commonly used in dentistry to create a digital scan of the patient's mouth. Removing impressions from the process would not only mean that dental work is completed more quickly, but there would be no physical shipping of impressions with the potential for loss or delay whilst in transit.
3D printing
During the 3D printing process, an advanced laser melting system builds up each framework in a series of successive layers. A high-powered laser beam is focused onto a bed of powdered metal and the selected areas consolidate into a thin solid layer. Successive layers of powder are then spread over the first, until every layer has been built. The solid frameworks are then taken from the machine and the product is dressed, grit blasted, and inspected as part of an ISO13485 quality management system.
The benefits of digitalisation
Swift Dental Laboratory manufactures crowns and bridges, prosthetics and supportive chrome work, all of which are based on patient impressions taken at dental surgeries across the UK. Before working with Renishaw, Swift Dental Laboratory used lost-wax casting to create porcelain fused-to-metal (PFM) frameworks.
As the laboratory's volume of work increased, Swift Dental started to consider the potential of digital design and advanced manufacturing to speed up processes and increase efficiency.
We supplied Swift Dental Laboratory with one of our AM250 additive manufacturing systems, which uses a high-powered ytterbium fibre laser to fuse fine grained, metal powders together to create a final three-dimensional structure.
The AM250 is coupled with Renishaw's DS30 blue light scanner, which creates a digital copy of a die stone model which is then used to create the framework. A file is then sent to the AM250 and the framework is produced from 40 micron layers of cobalt chrome powder. For a build of around 200 units this takes between 8 to 12 hours depending on the volume of the parts being produced.
Through our additive manufacturing technology, we have greatly improved the efficiency and accuracy of Swift Dental’s processes. Before introducing the AM250 and DS30, around two products in every ten would need a rework after the end-customer's first fitting – this has reduced significantly. The reduction in reworks is a particular benefit to dentists as it helps reduce the number of appointments needed for each customer, which has a significant effect on the revenue of the practice.
Towards the end of his run as president, George Washington became so embarrassed about his dentures, which often clacked and creaked as he spoke, that he became a recluse. Fortunately, today's dental industry has become more skilled and technologically advanced, meaning that there are always alternatives to poorly-fitted, unsightly dentures like Washington's.
