Ailing and failing All-On-X cases and how to treat them

Dr. Dan Holtzclaw discusses some reasons for implant failure and a possible solution for certain types

Introduction

Over the past 25 years, the All-On-X dental implant treatment protocol has revolutionized full-arch dental implant rehabilitation and, quite frankly, radically changed implant dentistry (Figure 1).¹ For those of us old enough to remember, there once was a time when full-arch implant dentistry entailed a cornucopia of bone-grafting procedures which increased morbidity, pain, cost and treatment time for patients (Figure 2).² It was not uncommon for patients to wait up to 2 years for restoration of their atrophic arches and/or undergo multiple bone grafting procedures only to later discover that they still did not have enough bone to adequately facilitate a full-arch implant-supported prosthetic. The All-On-X treatment protocol remedied this situation for many patients allowing for same-day immediate loading of dental arches sans bone augmentation in most cases.³ Early skeptics of this procedure have been heartily proven wrong with dental literature repeatedly showing high survival rates for All-On-X treatment.^4,5 While the success of this procedure may encourage us to pat ourselves on the back as a profession, we should maintain a discerning eye and consider how this treatment has held up over time.

The vast majority of All-On-X publications report data that encompasses 12-36 months^6,7 with occasional studies extending to 5 years.^4,8 In general, these studies report high success rates in the mid-to-upper 90 percentile range,^3-8 but longer studies begin to show a decline in performance. With 10 years of follow-up, Karoussis, et al., documented a cumulative conventional dental implant survival rate in All-On-X treatment as low as 90.5%.⁹ A recently published study by de Araujo, et al., likewise documented 10-year cumulative survival rates for All-On-X conventional dental implants at ~90%¹⁰ while Park, et al., found conventional dental implant survival rate at 89.08% in a mean follow-up of 12.6 years.¹¹ As time stretches even further, Simonis, et al., documented a cumulative All-On-X conventional dental implant survival rate of 82.94% at 16 years.¹² Finally, as we reach some of the longest reflective evaluations of this treatment, survival shows an even further decline.

In 2022, Vrielinck, et al., published a study evaluating over 20 years of All-On-X implant treatment.¹³ This study was somewhat unique in the fact that the patients in this study had All-On-X treatment that used a combination of conventional and zygomatic dental implants. As remote anchorage implants were needed for the participants in this study, it is safe to assume that the maxillary arches involved were of a more atrophic nature. A total of 72 patients were evaluated, of whom 18% were smokers, 8.3% were bruxers, and 2.8% diabetic. The study population was nearly evenly split between male/female, and average age at treatment initiation was 57.8 years (range 31-78 years). With follow-up reaching nearly 22 years (mean 12.8 years, range 2.2-21.9 years), survival rates for conventional implants followed an early pattern that mirrored previously published dental literature with 95.3% at year 1 and 94.8% at year 2. As time extended, conventional implant survival dropped to 93.0% at 5 years and 90.5% at 10 years. While these findings show a consistent decline, All-On-X conventional implant survival is still above 90% and consistent with previously published studies.

Few All-On-X studies stretch beyond a decade of follow-up and this is where Vrielinck’s study becomes very interesting. At 15 years, All-On-X conventional implant survival dropped to 81.6%, and at 20 years, a precipitous decline to 67.7% was recorded. With the first decade of Vrielinck’s findings in this study paralleling previously published dental literature, it is logical to forecast that the survival rates for conventional All-On-X implants in other studies will likewise follow suit. Bearing this in mind, it is safe to assume that as a profession, we can anticipate seeing a deluge of ailing and falling All-On-X cases as time progresses.

Why do conventional dental implants fail over time with All-On-X treatment?

With multiple published studies showing consistent data, it is safe to conclude that ailing/failing dental implants are expected and “normal” as time extends from the initial date of All-On-X treatment. These studies were performed by different clinicians from all over the world using a variety of implant systems with diversity in both surgical and restorative protocols. This begs the question, with such a large number of clinicians showing congruent findings, why do conventional dental implants have an increase in failure rates over time in All-On-X treatment?  The first culprit that comes to mind for many clinicians is that implant failure is a fault of the patient due to poor adherence to post-restorative maintenance. Published dental literature certainly supports the notion that failure to comply with maintenance protocols leads to poor outcomes over time. In dentate patients, tooth  loss, and numbers of decayed, missing, and filled teeth (DMFT) have proven to be lower with high adherence to maintenance.¹⁴ Likewise, systematic literature reviews and meta-analyses have also shown that poor or irregular adherence to maintenance leads to decreased outcomes for dental implants.^15,16 Is it fair, however, to completely blame dental implant issues on noncompliant patients? According to published literature, the answer to this is a resounding “No” as authors have noted, “…it must be stressed that even in the establishment of PIMT [peri-implant maintenance therapy], biologic complications might occur.”¹⁵

If dental implant complications and failures cannot be fully attributed to noncompliant maintenance, what are other means by which issues may occur? Summary and consensus statements from leading organizations such as the European Association of Osseointegration note that mechanical complications may occur in up to 39% of All-On-X restorations²¹ while other individual studies note long-term issues such as prosthetic screw loosening, multi-unit abutment loosening, and component/prosthetics fracture.^17-20 Many of these issues are often correlated to cantilevers which are a hallmark of All-On-X treatment.^17-22

All-On-X finite element analysis studies have consistently shown that longer prosthetic cantilevers produce increased stress values in peri-implant bone, abutments, prosthetic screws, and prosthetic frameworks (Figure 3).^23,24 Regarding bone, this stress tends to concentrate at the implant platform adjacent to cantilevers, and overloading is associated with increased per-implant bone loss.^23-25 This bone loss often exposes dental implant threads, and long term studies up to 20 years have shown exposure to or beyond the second implant thread in nearly a quarter of fixtures.²⁶ When the roughened surface of dental implants become exposed, bacterial adherence may increase should mucogingival recession occur. If this happens, the bacteria and endotoxin-laden surface of the implant elicits an immunologic host response that results in osteoclastic activity and bone destruction.^27,28 Marginal bone loss at the neck of implants is also exacerbated by micromotion that may develop with loosened prosthetic and/or abutment screws.²⁹

While it may be tempting to blame All-On-X implant issues on patient compliance with maintenance protocols, dental literature proves that this is a complex multifactorial issue and that complications may develop as a normal consequence of this treatment even under the most ideal circumstances.

How can clinicians deal with ailing/failing All-On-X cases?

It can certainly be disconcerting when a patient has problems with their dental implants, especially in larger cases such as All-On-X treatment where failure of one fixture may lead to loss of the entire prosthesis. First and foremost, it is important to remember that dental literature unequivocally demonstrates that dental implants will have complications and fail.^21,22,26,30 This is an indisputable fact. Over my decades of dental implant experience, I have had multiple complications/failures, and I will continue to have them. Anyone who thinks otherwise is deluding themselves and is not supported by published literature. When these problems occur, it is important to know treatment options available to either extend the life of the implants or replace them with suitable alternatives.

As noted earlier in this paper, one of the most common problems seen over time with All-On-X treatment is exposure of implant threads. If adequate amounts of keratinized gingiva are present, detoxification of exposed implant surfaces may be performed at maintenance visits, and the frequency of these visits may be increased. Patients should also be instructed to meticulously cleanse these areas at home. If minimal amounts of keratinized tissue are present, or if significant amount of implant thread exposure is noted, soft and hard tissue augmentation may be performed.^31,32 In the maxilla specifically, a technique which I have been finding great success with is plasty of exposed implant threads with simultaneous tissue augmentation via pedicled connective tissue grafts (Figures 4-8).

Implantoplasty is a clinical procedure in which a finishing bur is used to eliminate exposed implant threads to create a smooth surface, which is then polished with additional rotary instruments. This implant surface modification reduces bacterial endotoxin adherence, creating a more favorable peri-implant environment.³³ When implantoplasty is combined with soft tissue grafting to improve gingival phenotype, long term favorable results can be achieved.³⁴

While these techniques can extend the lifespan of ailing All-On-X cases, instances of more significant bone loss or outright implant failure require different approaches. Firstly, the cause of implant failure should be considered, especially in cases of excessive cantilever, inadequate support, poor bone quality, etc. Second, the amount of residual bone remaining following planned implant removal needs to be adequate for not only replacement of the failed implant, but also to create favorable prosthetic support which prevents recurrence of failure. Often, preexisting maxillary atrophy combined with bone loss from failing implants necessitates placement of remote anchorage implants such as zygomatic, pterygoid, and transnasal fixtures.²² These highly specialized implants utilize dense type 1 bone for anchorage which does not atrophy with tooth loss.²² As such, these implants are ideal solutions for All-On-X patients who have experienced severe amounts of bone loss with failing implants.

When determining which of these implants to use and where to place them, the PATZi protocol is a useful treatment algorithm which can guide the clinician.^22,35 This protocol makes use of nearly all implant styles and may result in a near infinite combination of fixtures to treat virtually any condition of the maxilla. For example, Figures 9-13 document a case in which failing All-On-X treatment resulted in severe maxillary atrophy, and the PATZi protocol was used to rehabilitate the patient with a combination of pterygoid and quad-zygomatic implants. Without the option of remote anchorage treatment, this patient would need to endure multiple large bone grafting procedures entailing additional morbidity, cost, and time for the unguaranteed possibility of future implant treatment. Furthermore, the patient would need to forgo wearing a denture during much of the healing process to avoid putting pressure on the bone grafts. By using the PATZi protocol with pterygoid and quad-zygomatic implants, the patient was able to receive an immediately loaded fixed prosthetic without the need for bone grafting.

Conclusion

The All-On-X treatment protocol has revolutionized dental implant treatment and now has 25 years of documentation to support its use. Like all treatment of biological systems such as the human body, complications will occur, and All-On-X procedures are no exception. Recent publications with long term follow-up of 20+ years have shown a verifiable trend of problems with conventional All-On-X dental implants that escalate with extended time. As the number of patients treated with All-On-X procedures has dramatically increased over the past decade, and these people continue to age, dental implant professionals will see an increased need to remedy these maladies. In addition to providing dental implant life extension measures such as implantoplasty for ailing All-On-X fixtures, remote anchorage techniques such as zygomatic and pterygoid implants will be required to rehabilitate cases with more severe problems. These remote-anchorage fixtures are highly complex surgical procedures and should only be attempted by clinicians with extensive training and experience with dental implants.