Many general dentists don’t have the opportunity to do digital implant planning the way they would like. They would typically like to start with the crown down, taking a prosthetic approach, before placing the actual implant. However, many patients come in ready to move forward with the placement of an implant, which is where dentists must start. Unfortunately, the placement isn’t always perfect in those scenarios.
That is where digital implant planning comes in. Cone beam computed tomography can help to improve the entire process, from diagnostics and treatment planning, to placing the implant. Dr. Ben Bringewald, a general dentist, offered his insights on improving placement in his recent webinar, “Digital Implant Planning in Action.”
How CBCT improves diagnostics
General dentists are accustomed to reading 2D images, such as bitewings, PAs and the Pano axis, very quickly. Many clinicians have seen so many normal 2D images that if anything relevant is not captured, they can easily spot gaps in the imaging.
With a CBCT machine, dentists can rely more on the imaging to reveal abnormalities, because 3D images provide a more comprehensive view of the mouth than 2D versions. Investing time in learning how to use the CBCT machine can pay off in better diagnostics, so dentists have a comprehensive view of the situation during diagnosis or prior to treating.
One critical step to improving the diagnostic process is to learn how to position the machine properly. A CBCT provides a view of three different sections: the axial view, the cross-sectional view and the tangential view of what is essentially the whole head. For a thorough view of the patient’s mouth, it is recommended that you go through the axial view — top to bottom and left to right, and then front to back. In those areas, look for anything that looks “off” in the sinus and the temporomandibular joints. If you have a big enough field of view to capture the airway, you will need to see the maxilla, the mandible and any pathologies located there or in the dentition.
Sometimes, in the course of doing this, you will see abnormalities that require further investigation. One patient came into Dr. Bringewald's clinic with concern around the loss of a crown on the lower left, around tooth number 20. A 3D image caught an abnormality around numbers two, 15 and 19. Dr. Bringewald’s practice uses a Dentsply Sirona CBCT machine and Sidexis software and has access to a group of radiologists associated with them. He sent the image to the radiologists for review. They found that the patient had a calcified lymph node, a condition that otherwise would not have been seen on a 2D image and can be a sign of ongoing infection. Fortunately, no further action was needed.
In another case, a patient came into Dr. Bringewald’s office for a routine checkup. A 2D scan of his mouth looked good, but the CBCT results showed pathology on tooth number two that the 2D scan had missed. It turned out that the patient had been experiencing frequent sinus issues. The treatment plan called for replacing missing teeth on the lower right. Additionally, CBCT imaging revealed a lesion on the lower left. Dr. Bringewald is now investigating that situation. Ultimately, in both of these cases, having the CBCT imaging available helped Dr. Bringewald make a more accurate diagnosis, guiding him on how to proceed.
Using CBCT for treatment planning
Dentists want to avoid positioning implants in a way that requires re-implantation later. The CBCT can be used to improve treatment planning, so fewer procedures need to be repeated later.
So, what does treatment planning with the CBCT look like in the clinic? Initially, dentists can use Chairside Economical Restoration of Esthetic Ceramics, otherwise known as CEREC, to connect to their regular case system. For example, one patient came to see Dr. Bringewald with a bridge for teeth numbers 29 through 31. The bridge was failing, and tooth number 31 had fractured underneath the original bridge. When the patient came in to get his crown done, he asked if it was possible to get some teeth back into that area.
While the crown was milling through the CEREC, Dr. Bringewald’s team took a CBCT scan. The CBCT impression started with making sure the panoramic curve editor was positioned correctly — effectively setting up the 2D panel from the 3D imaging — so when he later navigated to set up the nerve position, there would not be a lot of overlap.
With Dr. Bringewald’s patient, the CBCT revealed the fresh extraction site where tooth number 31 used to be. As it turned out, number 30 had already been gone for quite a while.
Informed by the image, Dr. Bringewald prepared to do the prosthetic planning for this patient. Under “restoration type,” he selected the prosthetic planning tab. This allows dentists to choose the type of crown they want, the same way they would with other CEREC restorations. He used that tab and opted for a biogenetic crown.
Then it was time to position the implant using the CBCT in conjunction with the CEREC. In this case, Dr. Bringewald had a complete intraoral scan done for the upper and lower buccal bite. He then determined how he wanted the crown to emerge, which is performed similarly to a pontic (artificial tooth) for a bridge. Once he created an outline, he selected the margins.
As Dr. Bringewald noted, the restoration plans and design can be adjusted, just as they would with any other set of CEREC crowns. After making slight adjustments, he successfully placed the crown and then exported the files.
Dr. Bringewald returned to the exam to plan the nerve, using the SICAT suite in the software. This suite includes four plugins. One commonly used plugin is the implant suite. Endodontists may also find themselves using the endo suite frequently. The other suites are the airway suites and the TMJ or function suite.
Once the nerve was planned, Dr. Bringewald was ready to add a digital impression, using either SSI files or SIXD files. As he explained, when you merge the teeth from a digital impression, you can select up to five buttons in each arch. You want to select as many natural teeth as you can and stay away from any teeth that are restored, if possible. Note: Teeth that are heavily restored or have amalgam restorations or crowns may cause scatter radiation that may distort the image.
You must also verify and make sure the stitching worked correctly, selecting the option that lets you see how the outline of the stitching lines up with the teeth.
Dr. Bringewald’s last step included planning out the implant. Since he used SIXD files, the software already knew which tooth he designed. As he pointed out, if you are looking at implants that are part of the SICAT suite, every single manufacturer and its implant lines are in there. You can configure “favorites” to avoid unnecessary scrolling through the options and speed things up.
There are some other features of the software that can make digital implant planning easier, Dr. Bringewald mentioned. The software is integrated with four different guides. With one guide, you can add a sleeve — part of the surgical guide that has a metal ring, which allows the drill to have the proper orientation. There is also an OptiGuide, which lets you take impressions, such as the digital intraoral impression. The classic guide, another option, has an actual scan plate you can use for impressions in situations where a patient has a lot of crowns or very heavily restored dentition. And finally, there is a DigiGuide, which is essentially a SICAT that provides you with an STL file. You can print the file at the office or a local lab but, keep in mind, you or the lab will still need to add the little metal sleeves. Dr. Bringwald ultimately chose the OptiGuide in the case of his patient, which allowed him to successfully complete the implant.
Conclusion
Placing implants can be challenging. Using CBCT and advanced software can make many aspects of the process easier, from diagnostics and treatment planning to the actual placement of the implant itself. Once you master the technology and related software, it can greatly improve the precision of the process and reduce the need for re-implantation later.
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