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Luke S. Kahng is an accomplished lab technician, specializing in high-end ceramic restorations. Luke has served on several major dental journal boards as a contributing member. Luke invented the Chairside Shade Guide: Volumes 1 and 2 and then expanded the offering to a unique ceramic shade guide system named the Seasons of Life Selection. He is owner and President of his own lab, LSK121 Oral Prosthetics, located in Naperville, IL. He has published over 100 articles in major national dental publications.
Luke S. Kahng, CDT, shows a technique for using PMMA material in a CAD/CAM system to fabricate highly esthetic temporaries.
We used to fabricate our temporaries with acrylic by hand, and, for higher-end long-term bridges, we would often use composite. This particular case study will explain what PMMA (defined by webopedia.com as “short for polymethylmethacrylate or, more correctly, Poly (methyl methacrylate), PMMA is a clear plastic acrylic material that can be used as a replacement for glass”) is and how we can successfully use the material in the dental world.
We can utilize technology, especially for implants, to create long-term temporaries through the use of a CAD/CAM machine. A good example of what we can use the material for is with a full-mouth implant case scanned and then copy scanned with a wax try-in already set up.
The exact material used in this patient’s case is called PREMIOtemp (primotecusa.com) and defined as multilayered PMMA CAD/CAM milling disks used for long-term temporary restorations, short-term provisionals and as a prototype for implant restorations.
We can follow the denture wax try-in and add more pink color to create more elaborate provisionals. We can copy scan the scan and follow the incisal length, cut the gum line and make it deeper with composite then apply over the top of the gingival area. Hiossen implants had been placed in the patient’s mouth, and the dentist requested the lab fabricate very nice long-term temporaries in a screw-retained bridge restoration.
See this process step-by-step in the following slideshow.
Step 2 The author milled PREMIOtemp material for the temporary restoration using a Motion Mill Amann Girrbach machine.
Step 4 The sprue was cut and placed on the model to ensure fit. We don’t have to apply a gum tissue layer at this point if the dentist does not require it. The cost is less that way, but some dentists do prescribe this aspect of the restoration.
05 The author next applied ceramic composite, GC AmericaGradia #24 first, and then overlaid it with Gradia #23. The application was intended to imitate natural gum tissue for the patient in the mouth. The author next contoured and shaped the gum area.
Step 6 He then applied OPTIGLAZE from GC America in four colors with maximum color to create natural appearance in the gums.
Step 7 He next applied Opal Effect to the incisal 1/3 for a more natural-looking restoration, as shown in this image.
Step 9 He then applied occlusion stain and created a white horizontal line. In between the teeth, he applied a warm orange stain effect.
Step 10 With an A1 base application, he was able to maximize the natural-looking effect all dental technicians hope to achieve in their restorations.
Step 11 Next, we see the results of the light-curing stage. We can note the difference between the three colors and the maximizing and mimicking of the natural tooth colors with white, blue, ochre, and ivory stains, which appear to be different in each application.
Step 12 The provisional was placed on the model over the seven implants for placement to be verified with the verification jig. Underneath the implants is a titanium base, which required correct torquing to be fit on the model in the most precise manner.
Step 13 Finally, the author took an occlusion view shot, left-side view, and a right-side view before photographing the final restoration
It is simply amazing the changes and developments there have been in the dental lab industry even recently! We used to work mostly with acrylics but now have developed an even more sophisticated design, especially with CAD/CAM digital design technology from our own hands.
Even more options than ever are available. The good news for technicians is that machines can’t do everything! We still need our hands for our final artistic and natural touches to maximize our final product, which also increases our profit and value!