…it seems that we are replacing many direct composites more frequently than their old amalgam predecessors. This is due to fractures, wear, and marginal decay.
|Cervical caries in Class II resin box forms is surprisingly common. What can be done to prevent it? (Image reprinted with permission from Clinicians Report.)|
With all of the discussions of CAD/CAM, everyone’s focus is on indirect restorations. We talk about accurate marginal fit, new cements, durability, and longevity. New materials, such as CAD zirconia and lithium disilicate, as well as milled or printed appliances, are all the rage. But there is still a world of direct restorations and good old-fashioned analog lab work. Master technicians are still hand building full ceramic and ceramic-fused-to-metal restorations. There are certainly computer programs that allow an artistic virtual technician an opportunity to create beauty on the screen and transfer it to the finished product, but, perhaps being old fashioned, I can still get excited when I see a hand-built crown. There are also advances in removable prosthetics with new printed dentures and, in fact, 3-D, metal-printed frames, bars, and other formerly cast (or milled) structures.
Keep in mind that, at this time, there is still no digital impression system available that can scan a fully edentulous arch. The digital dentures all still start with an excellent traditional impression. Once available, that is scanned, and other measurements (vertical, bite, etc) can go into the digital flow. At the recent California Dental Association meeting, I saw a measuring device from Suni Medical Imaging that was somewhat like a digital face-bow. The measurements were transferred to merge the cone beam and digital impression scans, which articulated the cases using the actual movements of the patients’ TMJs.
Along with “good old-fashioned” lab work, we still have to look at direct restorations in the dental office. Composites and, dare I say, amalgams, which are still being placed around the world, as well glass ionomers and combinations of many of these materials, are being created every day. There is also a new world of bioactive restorations, liners, and cements that promise to repopulate margins with new calcium and even simulated enamel. There are those staunch digital dentists, though, who have systems that can create inlays and onlays on the spot and can actually do a few MODs in almost equal time to doing direct restorations with predictable margins and, more importantly, proper contacts. A great example can be seen in a video from Dr. Todd Ehrlich’s Digital Enamel series (vimeo.com/196780259). I am not arguing that fact, but the majority of practitioners would prefer (at this time) to create composite restorations. There is no shortage of new restorative materials coming to the marketplace, and we are seeing new classes of materials, such as ceramic-based restoratives and various combinations of ingredients. Many of the new products incorporate fluoride release, calcium ion release, and even antibacterial formulations. The reason for this is partially due to early failures of many of the new composite restorations in comparison to the longevity of well-placed amalgams. In many situations, though, we are replacing 20- to 30-plus-year-old amalgams that have leaking margins, fractures, and recurrent interproximal decay; sometimes, it’s strictly for cosmetics. But it seems that we are replacing many direct composites more frequently than their old amalgam predecessors. This is due to fractures, wear, and marginal decay. The defenders of composites state that, in these cases, poor techniques, no rubber dams, and/or uncured materials were used; voids were present; and more. Also, those of us brought up on GV Black amalgam preparations have to understand that composite preps, as well as inlay and onlay preps, are quite different partially due to the fact that they are bonded. For new preparations, the term “minimally invasive” comes to mind, which is really another way of saying, “Keep as much of the original tooth intact” and to forget “extension for prevention” in its prior format.
|An indirect try-in (top) and final restorations (bottom). (Images courtesy of Dr. Todd Ehrlich.)|
And what about the failures? This was all just presented in a very good report by the CR Foundation in its June Clinicians Report. The article, “Epidemic of Cervical Caries in Class II Resin Box Forms,” was quite enlightening. I encourage you to subscribe to Dr. Gordon Christensen’s Clinicians Report at (801) 226-2121 or cliniciansreport.org to get up-to-date reviews of products, processes, and more in dentistry. Many people are under the false assumption that the reports are all Dr. Christensen’s own research and beliefs. Although that plays into it, keep in mind that there is a sophisticated research institute and 450 CR evaluators—everyday dentists—who are testing out materials, products, and more and reporting the results. The bottom line of every review states the percentage of evaluators who would use the product in their practices, as well as a rating and a “worthy of trial by colleagues” designation. In this particular report, they outlined potential problems and solutions to early failures. Steps are covered, such as the use of glutaraldehyde/2-hydroxyethylmethacrylate and resin-modified glass ionomer base/liners, as well as how to be sure your curing light is adequate. I think this is a must read for all dentists, and I encourage you to find Gordon at a CR presentation or one of the many dental meetings around the country. I have grown up with Gordon throughout my career and have been lucky enough to have met him, and I can tell you that his passion is the same as it was 40 years ago. So step back from the digital rush and try to get back and improve your basics.