New Technologies Provide Options for Implant Bars
Design software, bar concepts, and materials options continue to evolve
By Robert Sarno, CDT
Synergy has long been the key to how well the surgeon, restorative clinician, and removables technician work together to guarantee the successful outcome of restoring the edentulous arch. In the future, the key will be how well the surgeon, restorative clinician, and digital technologist work together. A true understanding of the fundamentals of each discipline—removable prosthetics, digital design, implants, and surgical elements—will always be of the utmost importance. The most important factor, however, will be how well the implant planner and digital designer collaborate and communicate.
The constant upgrades to implant planning software today allow us an even more accurate look into the planning phases of our fully edentulous implant cases. The combination of various scanning options, including CBCT, digital impression, pre-operative, and 3D facial scans, provides us with more diagnostic information than most dental professionals ever thought possible. This information helps the dental team diagnose and classify the management of restorative space of the edentulous patient. It also allows the team to determine how much restorative space is necessary.
An ideal situation is 15 mm from the soft tissue crest to the proposed occlusal plane; a patient with this amount of restorative space could be a candidate for a full range of restorative materials, bars, and attachments. In a case with 9-11 mm from the tissue crest to the proposed occlusal plane, the overdenture attachment type may be more critical and restorative materials may become more limited.
Understanding guided surgery helps us determine which material best suits our final restoration. Determining VDO, the number of implants to be placed, and the width and length of the implant dictates to some degree whether the restoration should be fabricated using titanium, chrome cobalt, zirconia, or a combination of these materials for even more strength. Sharing this information with all members of the restorative team (surgeon, clinician, and technician) helps ensure the predictability of the case.
In the event a surgical guide is not used for placement of the implants, a verified impression can be taken the day of the surgery. The position of the implants will always remain the same even after the tissues heal and some resorption occurs, allowing for the use of this impression as a master impression for the entire restorative process. The impression or model can be scanned and used for the design of the final bar and the digital file sent to a milling center for final CAM fabrication of the prosthetic structure.
Predictable Digital Workflow for Bars
A digital approach for the design and fabrication of implant bars allows a more precise method of implant placement and provides dental technicians with the opportunity to achieve a more predictable outcome that guarantees a higher success rate. CAD software from large implant companies provides pinpoint precision of the height, depth, angulation, position, and timing of the internal hex of the implant for members of the surgical team to provide same-day prosthetics fabricated in advance by the dental technologist. This technology combined with the geometries of newer and older prosthetic components provides a wide range of options for fixed edentulous and screw-retained restorations. All of these components are engineered with the goal of optimal tissue management, various angulations, and various gingival heights to provide custom solutions for each individual edentulous patient. Open-architecture implant planning software solutions offer constant software upgrades to their implant libraries for incorporating a wide range of implant, abutment, and surgical guide brands.
Increased adoption of the digital workflow process will provide technologists with a more predictable model and a more predictable outcome for CAM-milled implant bars, depending on which solution the patient desires—implant-retained for a more expensive fixed solution, or implant-supported for the patient who desires a cleansable appliance at a lower cost.
Bar Options
Major implant companies such as Nobel Biocare (nobelbiocare.com), Dentsply Implants (dentsplyimplants.com), Zimmer Biomet (zimmerbiomet.com), and Straumann (straumann.us) as well as outsource providers such as Dentsply Sirona (dentsplysirona.com) provide custom-milled bar solutions utilizing various materials, such as titanium and chrome cobalt. Complete bar/overdenture solution providers such as AvaDent (avadent.com) offer laboratories a digital outsource service option for the design, fabrication, and delivery of both the bar and overdenture. Independent milling centers such as Core3dcentres (core3dcentres.com), IMILLING (imilling.com), and CreoDent Prosthetics (creomc.com) also provide CAM implant structures.
Various specialty milling centers offer a more complex array of products based on CSG (constructive solid geometry) technology, which allows the CAD operator to create a complex surface or object by using Boolean additions or subtractions. PREAT Corporation (preat.com) offers a secondary 3D-printed frame that provides a friction-fit primary and secondary framework with different pearl finishes and a wide array of plungers, side screws, and attachments. To achieve this, the secondary framework is slightly over-printed and then milled for an accurate fit to the primary bar.
Panthera Dental (pantheradental.com) has developed a proprietary software for the design, in addition to a scanner that scans the implant replicas instead of scan bodies. Panthera also uses a similar technology for milling for its secondary frameworks but also offers zirconia and PEEK as options, adjusting the milling parameters in the finishing process for a truly frictional fit. These solutions may cater toward severely compromised cases due to poor implant placement or due to the lack of proper diagnosis and planning.
There are still only a few providers of milled bar design solutions, but many companies have plans for integration with open-architecture implant-planning software, thus integrating bar manufacturing in the process of immediate load full-arch cases. Planning and prefabrication of titanium immediate load hybrid full-arch cases could be a reality within 2-3 years for the larger manufacturers; for some smaller laboratories, it already is.
Bar Materials
A few years ago, in-house milling of various metals direct to fixture looked extremely promising; today, it may seem unrealistic without proper registration with the FDA. This may highlight the true benefits of high-performance polymers.
The introduction of materials such as Pekkton® (anaxdent North America, ), JUVORA™ (JUVORA Prosthetic Solutions, juvoradental.com), BioHpp (Bredent, bredent.com), and Trinia™ (Shofu Dental Corporation, shofu.com) has opened a whole new market for the laboratory in the near future. These materials have very similar characteristics to human bone; they are shock absorbing, lightweight, and metal-free.
A primary benefit and advantage of these materials is how well they all integrate with existing CAD/CAM software. No expensive upgrades will be necessary for the smaller laboratories; the in-house CAM capabilities on even the smallest of milling units are sufficient. This allows the laboratory full control of the materials and time savings in addition to significant advantages with the high flexibility in the choice of veneering materials, such as composites, PMMA shells, denture teeth, and ceramic crowns. The restorative options range from primary bars to secondary frameworks. These materials have very high frictional properties with hand-milled zirconia when used in conjunction with a tactile scanner or by adjusting the milling parameters after designing.
Conclusion
Expanded digital design capabilities, new bar concepts, and advanced materials options allow dental laboratories to provide improved prosthetics for edentulous patients via implant-retained or implant-supported structures. As material options and milling technologies continue to evolve, so too will the ability of the dental team to provide patients with better prostheses.
Robert Sarno, CDT, is the Owner of Pinnacle Dental Laboratory, Inc. in Chesterfield, Missouri.
