WHEN DIGITAL MEETS ANALOG IN COMPOSITE INJECTION. BY CSONGOR SZEKELY, BYRNES DENTAL LABORATORY Leave a comment

Having recently attended a course at Skillbond, hosted by Lisa Johnson and sponsored by GC, I was keen to see if we could implement the process easily into Byrne’s Dental workflows. Wherever possible, a Byrne’s Dental Lab workflow is as digital as possibly bar the final artistry, so all diagnostic and try in stages are digitally designed and manufactured. However, composite wrap arounds are one of the areas that we, as a lab, really struggle to digitise.
Lisa’s excellent course showed how we can take any form of teeth, and quickly and easily turn them into stunning, perfectly copied, final restorations, complete with a metal insert frame for much needed support.
Using a digital workflow, we design the diagnostic stages in CAD and when visually approved, we then 3D print a try in. Usually on temporary cylinders, these can also verify the implant cast or printed model, as well as aesthetics and occlusion, cost effectively and easily. Once this try in have been approved, we can use this file to design the metal work internally and ensure the metal does not protrude through the diagnostic case. We then mill this framework using an outsource company (in this case, to Createch Medical from the Straumann Group). Now we have a metal frame and a diagnostic try, and the challenge is to ensure we duplicate this in a final restoration.
Conventionally, we would hand build the composite onto the bar, however human error can easily creep in, and it is also incredibly time consuming for a technician to copy a wax up perfectly in composite. In this case we used the GC Grade Plus flowable composites and the new injection method we learnt on Lisa’s course.
The 3D printed diagnostic was screwed to the model and the model was sealed in a clear window flask, in this case an Easy Form. Sprues to allow injection were fixed onto five locations. Four on the occlusal surface and one lower down on the lingual. The top was screwed down to create the sealed flask and then clear silicone was poured into the diagnostic and sprues and allow to set.
We then removed the top part of the flask and carefully pulled out the wax sprues, although they can be boiled out of needed. We then unscrewed the diagnostic from the model and placed the milled metal implant frame on and checked the frame did not contact the silicone. As it was so well designed in CAD, it did not. The metal frame was removed, pre-sandblasted, opaqued, cured as per GC instructions, then screwed back onto the model, and finally, flask top placed in position and screwed down.
Using GC flowable composite dentine, the material was then injected into the mould. Watching through the clear silicone ensures it’s easy to inject and no air bubbles remain. This is then cured in the GC Labolight DUO and then the top section of the flask is removed. The sprues were removed, followed by the incisal sections being carefully hand-cut back, as per the aesthetic demand of the case. Once this is done, the bridge is cleaned, primer added, the top section of the flask re-attached, and GC Grade plus incisal material was injected. Again, checking for no air bubbles through the glass clear silicone and then cured. The top part of the flask is removed, and the bridge is nearly finished. This is the main advantage of using this technique – it is a huge time saving and it replicates the diagnostic stages perfectly.
This was an FP3 case, so the pink section was built up manually using GC Gradia Plus pinks and then cured. Some minor trimming and some surface staining using GC optiglaze and the bridge was finished in a remarkable amount of time with a perfect copy of the diagnostic.
In this crazy busy lab world where we are all fighting for time, this method using injection and silicones from an easily made 3D printed try in really simplifies the process. Using this method reduced technician hours, yet still allowed us to deliver a top class product and is identical to the diagnostic stages.