All-on-X implants revolutionized prosthetic dentistry, providing patients with a strong and remarkably natural-looking fixed full-arch prosthetic that can last for many years.
"The All-on-X treatment is the pinnacle of replacement dentistry," says Harshit Aggarwal, MSD, prosthodontist, Center for Dentofacial Aesthetics, Annandale, Virginia. "Nothing else we have available now is better or closer to what Mother Nature gave us in terms of replacements."
The use of such restorations has grown in number over the past decade as both clinicians and technicians are increasingly becoming interested in this form of implant-based restoration. And who can blame them? Various studies have shown success rates above 90% in long-term follow-up.1-3
Yet with more technicians and clinicians turning to this restoration, opinions and recommendations for material selection and workflow widely differ.
With so many different available material options and more coming to market all the time, we turn to the experts for advice on how they sort through the options and why they select a specific material or multiple materials for each case.
Factors Dictating Material Section for an All-on-X Case
Technicians and clinicians unfortunately may differ in their opinions on materials to use as well as who decides what is ultimately used.
"The decision of materials has to come from the clinician, it is no one else's responsibility because, at the end of the day, the clinician has to live with it," insists Aggarwal, who also founded Orris Dental Lab. "Clinicians should definitely lean on experienced technicians and ask them their opinions on manufacturing and other things that may make a restoration challenging to fabricate, and that could be a part of the decision making. But the final decision is always the clinician's."
Whereas Alexander Wünsche, CDT, President of Zahntechnique Dental Laboratory in Miami Lakes, Florida, and a member of the Inside Dental Technology advisory board, says client preferences are one of the last questions he asks, in case their preferences do not match the qualifications defined by patient characteristics, function requirements, and esthetic parameters. He is forthcoming with clients if their preferences would lead to a poor-quality restoration.
Among his most important factors in material selection are strength, stability, and spacing. He also takes into consideration the age of the patients as a metric for how long the restoration needs to last. Wünsche knows, for example, that a zirconia will mostly likely not wear down much over 60 years of use if the patient is, say, 40 years old when receiving their implant. However, a 3D-printed nanoceramic restoration will show wear marks after 3 to 4 years, so he considers this option more in older patients where they are less likely to wear out the materials.
Age also factors in because clinicians often prefer softer materials for younger patients so it is more forgiving and does not negatively affect bone stability with the force of the bite on the implant. In this instance, if it aligns with the needs of the case, Wünsche recommends a high-performance polymer with a PEEK or PEKKTON construction and ceramic crowns on top as this type of restoration provides more of a suspension effect. However, this approach is considered just another option and is not recommended for younger patients.
When the case allows for it, Wünsche prefers working with zirconia and integrated titanium bars. Jack Marrano, president of Absolute Dental Services in North Carolina, is also a big believer in using zirconia. He insists that no other material should be used for such a restoration. "There is no better material with a better track record for an All-on-X restoration than zirconia, and the scientific literature is there to back that up," Marrano says. "Zirconia is king."
Andrew Pica, BA, RG, senior CAD/CAM technician, NuCrown Dental Laboratory, Cedar Grove, New Jersey, and adjunct lecturer, Restorative Dentistry Department, New York City College of Technology, takes it a step further and prefers a zirconia with a flexural strength above 1000 MPa.
At NuCrown, they choose to be more limited with their available materials so they know exactly how to work with each one. "We find that limiting the variables and getting very comfortable and precise with a select few materials gives us the ability to have the least chance of discrepancy and the greatest chance of success because, at the end of the day, you're not working on a pan, you're working on a person," Pica emphasizes.
At NuCrown, they generally use high-translucency multilayer zirconia from Argen as a part of their closed system because they trust the products of the company and their relationship with Argen. They have worked with their products enough to understand the differences in their shades and the nuances of each material. This perfectionist approach has clearly paid off, though. "We have about a 1% fracture rate and a 1% remake rate," Pica says.
With his All-on-X cases, Pica takes into consideration the expectations of the patient and doctor as well as implant position, anterior-posterior spread, restorative space, and patient history. Understanding the patient's oral history journey and the underlying issues leading to the restoration can be beneficial in addressing certain issues that could lead to future failures. Oftentimes patients can come from other clinics, looking for a fix with their All-on-X after experiencing prior repeat fractures, discomfort, etc. Evaluating and deciphering what led to the prior failures will better ensure a successful outcome.
Aggarwal gives the example of a high-flying lawyer who broke several temporaries in a short period of time as well as a ti-base implant due to his bruxing and grinding. He elected to make him a titanium frame with a cemented one-piece zirconia framework as the cement would act as a stress breaker and the overall design would have more flexibility and give, like natural teeth, with a layer of protection for the implants.
Many technicians say knowledge of prior issues and the success of a restoration comes down to ensuring that patient/clinical records are accurate. Marrano says every zirconia failure he has seen this year have all been due to inaccurate clinical records. When the dentist verified against the master cast, the bite was far off. "Bites, photographs, and verifications are of the utmost importance on the laboratory side; you have to protect the material," he says.
To protect the material, Marrano insists zirconia must be green-stage finished to prevent damage after sintering. He does not allow the use of steamers on zirconia to prevent thermal shock, or high-speed handpieces to prevent sparking. He says this comes down to understanding the material science and how best to handle the material.
According to Mark D. Williamson, CDT, DTC, Clinical Laboratory Manager, Bay Lakes Center for Complex Dentistry, Green Bay, Wisconsin, the biggest factor that impacts material selection for each case is spacing.
"A lot of times a doctor might send in a case that they say is going to be a typical hybrid acrylic All-on-4, but for that you need about 15 mm of space, if not more. So, the biggest thing that we fight with as technicians is the spacing," Williamson said. If the 15 mm is not there, then Williamson may instead choose a metal titanium mill substructure with an iBar and zirconia overlay. If there is only 10 mm of space, zirconia, too, may be likely to fracture.
Spacing also dictates material selection when there is not enough material to fill the need. Aggarwal explains that for patients with larger arches, the All-on-X design may not fit on the zirconia puck, especially taking shrinking into account, prohibiting use of the material. In this instance, Aggarwal switched to zirconia on top of metal.
Preferentially, Williamson likes to use metal titanium substructures with individual lithium disilicate crowns with pink composite. "I think esthetically and long term, it's bulletproof now; it's the best of what we have available," he says. His second choice would be a full-arch zirconia as it becomes more affordable.
Williamson also looks at cleanseability in selecting his approach to an All-on-X case. He explains that for an elderly patient with poor hygiene, an All-on-4 may be harder to clean with a WaterPik or flossers. In this case, he then looks to do a removable type of All-on-X restoration with a REBourke Bar by Panthera Dental, and stresses that the prosthetic has to be easy to remove if the patient is frailer.
Troubleshooting and Overcoming Issues With All-on-X
Williamson insists there is no perfect restoration, and there are pros and cons to every approach, and a possibility for issues and fractures.
Additionally, he points out that when technicians go against the rules and standards of a material, as set by the manufacturer, there is more of a chance for fractures and errors. "If you don't handle the material with respect, it's going to break," Marrano stresses.
Pica suggests that although some technicians may want to place blame on a specific material when things go wrong, many of the issues and fractures that arise are a result of human error, often due to a technician not knowing the materials or understanding the workflow well. "Really what it has to do with is the user-how we are using this material. When people reach out to me for advice or consultation about what is happening in their laboratories, 99% of the time it is user error, and it takes time to develop those techniques that are successful for you," Pica says.
To troubleshoot, he tells technicians to check their production line from start to finish including scanning, the milling process, the calibration and cleaning of their oven, and firing and cooling temperatures. At NuCrown they even implemented internal registry slips to know exactly who did what to pinpoint where an issue originated and maintain consistency.
Interdisciplinary Treatment Planning and Conversion Process
A pivotal part of a successful conversion of an All-on-X restoration is the treatment planning and communication between the dental lab, the clinician, and the surgical team. Some would also add the patient to that group. Others rely solely on the clinician to address concerns and expectations with the patient.
Williamson said that it works best for his workflow if discussions with the dentist take place upfront regarding expectations, costs, and timing, so they are not surprised later in the process by changes.
Aggarwal, however, says that all of the information he needs to design the final restorative piece come from x-rays of the patient's teeth, pictures, and a discussion with the patient of their esthetic expectations. He explains that from there, the treatment planning for All-on-X starts off similarly to the planning steps for a full denture-determining jaw and tooth position, selecting the teeth and how much to show, and it only differs when getting into the implants, which is when the clinician accounts for the technicians' input regarding optimal choices for the available space.
Aggarwal also makes sure to discuss placement with the surgeon prior to conversion to ensure optimal spacing of more than 5 mm between implants for proper cleaning and management.
Pica explains that at NuCrown, once they receive scans, models, impressions, and photos, they check the maxillary and mandible, occlusion, palate, and other landmarks to have sufficient information to create an immediate denture. Then videos of case analysis are sent to the dentist to defend and verify their design, placement, and thought process. From there, they mill a surgical denture and print a surgical guide, depending on the preferences of the surgeon for fully guided or not. The chairside conversion takes place with NuCrown's clinical team, and after the patient heals, adjustments can be made through discussions with the patient and clinician and even a redesigned prototype before going to finals.
Pica credits smooth conversions from his lab to great relationships with their clinical partners through establishing an early foundation and comfort level in trusting each other and working together for the best interest of each other and the patient.
As the owner of a boutique dental lab, Wünsche and his team are able to engage more directly with the patient from the start for photos and to get an idea from them of the problems to date and their expectations for the restoration.
From there, he creates a digital wax up with digital smile design that both the patient and clinician will see to ensure happiness with the design and esthetics. Then guides and provisionals are planned and fabricated leading up to the surgical implantation. Commonly, verification and testing of the prototype are done on the same day or following day, and 3 months or so later, the final is placed. His involvement with the patient and clinician throughout the process keeps him in-the-loop on all possible changes and questions.
Wünsche says that a smooth process and meeting the expectations of the patient relies on all members of the team-clinical, surgical, and technical. He has established templates for dentists to try to get them all on the same page with lists of everything needed to kick off a case, manuals for different scanning systems, processes with files, and more to simplify the process for the clinician so that they work together easily.
Quality of Life
Technicians and clinicians unanimously agree that proper All-on-X restorations have tremendous effects on a patient's quality of life.
"If you have a denture, it only restores about 20% of functionality compared to natural dentition. When you go to an All-on-X, it's upwards of 70% to 80% functionality in terms of chewing capacity and the ability for the patient to go through their day-to-day life with minimal interference from their dental prosthetic," Pica says.
In addition to allowing a patient with prior edentulism be able to chew and smile normally again, these implants can prevent the jawbone from deteriorating, which would change face structure over time.
Williamson explains the "emotional dentistry" aspect of getting an All-on-X restoration, that it is a life-changing procedure for many patients that can positively impact their self-esteem. "You have to remember that these patients were either in pain or maybe were always covering their mouth because they were self-conscious and now you've given them back their smile. Now they can function, they can speak, they can eat. Their health gets better and they become more confident," he says.
"It's really nice being a small part of something life changing. It's very rewarding getting to see it," Williamson adds of seeing the transformation chairside.
However, both Aggarwal and Wünsche highlight the need for more and thorough patient education to make sure that the All-on-X restoration is properly managed and cleaned for greater longevity. Wünsche believes that the ideal level of education comes from a combination of both the dentist and the lab technician.
Over All-on-X?
Even with everything said about the great benefits of All-on-X restorations, many technicians emphasize that there are other restorative options available for patients and suggest that perhaps too many All-on-X cases are being recommended to patients and being performed.
"I don't think that an All-on-4 is a blanket solution for everybody," Pica says. "I would like to see a little bit more conservatism in the presentation of the treatment."
Aggarwal agrees that more options need to be presented to the patients, or patients should even seek out second opinions before going for an All-on-X case. "All-on-X is being pushed now in cases where it's almost not even necessary, but it's being done because it's convenient," he says.
"We're over-All-on-Xing our patients," Wünsche says. "There are so many varieties of restorative workflows or options we can actually utilize nowadays that an All-on-X is not always the best." He believes that more removable options could be done instead of a complete fixed All-on-X prosthesis, but many clinicians are being pushed more and more in this direction.
"A likely reason why they're being overdone, even though it's an extremely complex protocol, is it allows us to start with a blank canvas when they're trying to restore based off of the existing dentition," Pica says. "Doing a combination of fixed and implant-depending on the existing condition, how the case is handled and prepped, treatment planning, etc.-could result in a final that is not as beautiful or esthetic as imagined. So, in a sense, it can be more difficult to plan a case off of an existing dentition than it is to wipe it clean and have a blank canvas. That's probably why clinicians are leaning in this direction, because overall they get a more uniform prosthetic and it's a little bit faster and easier to achieve what they want esthetically."
They each recommend opening discussions with clinicians when possible, and when the relationship allows for it, suggesting alternate solutions that are in the best interest of the patient.
Conclusion
The evolution of All-on-X restorations has undeniably transformed the landscape of full-arch rehabilitation, offering patients a reliable and life-changing solution. However, as experts in the field emphasize, success hinges not only on the selection of high-quality materials but also on a collaborative, interdisciplinary approach. The choices made by technicians and clinicians must be informed by patient-specific factors-age, function, esthetics, and long-term durability-rather than defaulting to a one-size-fits-all approach.
Ultimately, the success of an All-on-X case is not solely defined by the materials used but also by the synergy between the lab, the clinician, the surgeon, and the patient. With meticulous planning, adherence to material science principles, and ongoing education, dental technicians can continue to play a pivotal role in ensuring the longevity and functionality of these transformative restorations.
References
1. Korsch M, Walther W, Hannig M, Bartols A. Evaluation of the surgical and prosthetic success of All-on-4 restorations: a retrospective cohort study of provisional vs. definitive immediate restorations. Int J Implant Dent. 2021;7:48.
2. Maló P, Nobre MA, Lopes A, Ferro A, Nunes M. The All-on-4 concept for full-arch rehabilitation of the edentulous maxillae: A longitudinal study with 5-13 years of follow-up. Clin Implant Dentistry. 2019;21(4):538-549.
3. Maló P, Nobre MA, Lopes A, Ferro A, Botto J. The All-on-4 treatment concept for the rehabilitation of the completely edentulous mandible: A longitudinal study with 10 to 18 years of follow-up. Clin Implant Dentistry. 2019;21(4):565-577.
Figures and Images
