Full-Arch Implant Rehabilitation (All-on-4 / All-on-6)

Full-arch implant rehabilitation means replacing all the teeth in one jaw with a complete fixed bridge, screwed onto a limited number of implants — most often four to six. That is the logic behind the concepts known as All-on-4 and All-on-6: instead of placing one implant per tooth, the load of an entire arch is distributed across a few strategically positioned supports, some of which may be tilted to make better use of the available bone. This solution is intended for people who have already lost all the teeth in an arch, or who are about to, because their remaining teeth can no longer be saved. It differs from a removable denture: the prosthesis is fixed in place, the patient does not take it out, and only the practitioner unscrews it for check-ups. This article describes the principle, the indications, the treatment steps, the upkeep, the survival data reported in the literature and the limits — without promising a lifespan or a guaranteed result.

The aim is not to present the full-arch implant bridge as a permanent set of new teeth with no trade-offs. It is a major rehabilitation, reliable when properly indicated, but it remains a device placed in a living environment, involving surgery, a recovery period, lifelong upkeep and possible complications. That nuance is part of the information every patient is entitled to before deciding.

# What is a fixed full-arch implant bridge?

A full-arch implant bridge is a single-piece prosthesis covering an entire arch, restoring all the teeth in one jaw. It is not supported by the gums like a denture, but screwed onto implants integrated into the bone. This anchorage changes the stability: the prosthesis does not move while chewing or speaking, and it does not need to cover the palate.

In the All-on-4 and All-on-6 concepts, the complete arch rests on four or six implants. To compensate for bone volume that is sometimes limited towards the back of the jaws, the two posterior implants are often placed at an angle. In many cases, this tilting makes it possible to avoid or reduce the need for a bone graft or a sinus lift, while extending the prosthesis support further back.

The prosthesis is generally screw-retained rather than cemented: a screw-retained prosthesis can be removed by the practitioner for cleaning, inspection and repair, which makes maintenance easier.

# Who is this solution for?

Full-arch implant rehabilitation concerns two main profiles:

• people who have already lost all the teeth in one or both arches, who cope poorly with a removable denture or would like a fixed solution;
• people who are about to lose their remaining teeth, condemned by advanced decay or severe periodontitis, and for whom a comprehensive rehabilitation is being planned.

The choice is never automatic. It depends on the volume and quality of the bone, the condition of the gums, the bite, general health and each person’s expectations, and it is made after a full assessment. If you are weighing up the main families of solutions, the article Implant, bridge or denture: how to choose compares their advantages and limits before the question of cost, covered in What makes the cost of a dental implant vary.

The fixed full-arch bridge is not the only route for someone who has lost their teeth. A removable denture stabilized on implants can remain a relevant compromise, particularly when bone or budget limit the fixed options (see the comparison further down). The aim is not to push towards the most extensive solution, but towards the one that suits the situation.

# How many implants: four, six, or depending on the case?

The number of implants is not a fixed rule. The figures four and six correspond to documented protocols, not to a universal requirement.

The 6th ITI Consensus Conference (2018) summarized the data on the number of implants for fixed full-arch bridges. It concludes that in the lower jaw, there is no statistically significant difference in implant or prosthesis survival between rehabilitations supported by fewer than five implants and those supported by five or more. In other words, in the mandible, four implants may be enough in suitable cases. In the upper jaw, the bone is often of poorer quality, which may lead to favoring a higher number depending on the situation.

The choice between All-on-4 and All-on-6 is made case by case, according to the arch, the bone and the chewing forces. More implants is not automatically better: what matters is the overall planning.

# How does treatment proceed in Kénitra?

Full-arch implant rehabilitation is a structured pathway, never a single procedure.

# The assessment

The first step is not surgical. It is a full assessment: medical history, examination of the gums and remaining teeth, analysis of the bite and of oral hygiene. Periodontal health is decisive, because untreated inflammation compromises healing and the long-term stability of the implants.

Three-dimensional imaging is central. At the practice, the Dürr Dental Cone Beam (CBCT) analyzes in three dimensions the bone volume available and the position of the structures that must be respected — in particular the inferior alveolar nerve in the lower jaw and the maxillary sinuses above. It is this examination that determines whether tilting the posterior implants is enough to avoid a graft, or whether bone reconstruction is still needed. Digital impressions and computer-aided design (CAD/CAM) are then used to plan the prosthetic project and manufacture the prosthesis. This equipment describes a technical set-up; its presence is not in itself a guarantee of results.

When bone is lacking despite tilting the implants, reconstruction options and alternatives are covered in Dental implants when there is not enough bone: what are the options.

# The surgery

Placement takes place in a dedicated surgical suite, under local anesthesia, sometimes combined with sedation. When remaining teeth are condemned, they are extracted during the same session, then the implants are placed and angled according to the plan.

For bone surgery, piezosurgery uses ultrasound that acts on bone while sparing the surrounding soft tissues; it is an instrumentation technique, described here without attributing any quantified superiority to it. Choukroun’s PRF, a platelet-rich fibrin obtained from the patient’s own blood, may be used to support healing of the sites; it is an aid to early comfort, not a guarantee of success.

# Loading: immediate or delayed

One appeal of the concept is the possibility, in selected cases, of fitting a fixed temporary prosthesis shortly after surgery: this is immediate loading. It is not routine: according to the ITI consensus statements, it requires the primary stability of each implant to be confirmed at the time of placement. When that stability is insufficient, loading is delayed to let the bone heal.

One point is often misunderstood: a temporary prosthesis fitted in a single day is not the final prosthesis. The definitive one is made after healing and osseointegration, that is, once the implant has anchored into the bone. The choice between immediate and delayed loading, and the conditions involved, is detailed in Immediate or delayed loading of a dental implant.

# What does the survival data say?

Full-arch implant rehabilitation shows high survival rates in the literature, but these figures need to be read with caution.

The systematic review by Soto-Peñaloza et al. (2017, Journal of Clinical and Experimental Dentistry) on the All-on-4 concept reports survival of around 99.8% beyond 24 months. The authors nevertheless stress the limits of this data: methodological quality is often low, follow-up insufficient and participants lost to follow-up. Encouraging medium-term results, then, but to be interpreted with reservation.

Over a longer period, the longitudinal study by Uesugi et al. (2023, International Journal of Implant Dentistry), conducted in Japanese patients with 3 to 17 years of follow-up, reports cumulative survival that differs between arches. In the lower jaw it is around 98.9% at implant level and 96.7% at patient level; in the upper jaw it is lower, around 97.4% and 94.4%. The analysis identifies the upper jaw as the factor most significantly associated with poorer survival: the outcome is not the same above and below.

Finally, the systematic review by Kwon, Bain and Levin (2014, Journal of Dentistry) on hybrid fixed full-arch bridges reports high short-term survival (5 to 10 years), of the order of 93.3 to 100% for the prostheses and 87.9 to 100% for the implants, but points out how few studies extend beyond 10 years, which prevents firm conclusions about real-world lifespan.

Two cautions are needed. First, survival at implant level is not the same as survival at patient level: a patient can lose an implant without losing the whole rehabilitation. Second, survival is not success.

# Survival is not success

An implant or a prosthesis that is still in place is not necessarily problem-free. The 2017 World Workshop consensus (Berglundh et al., 2018, Journal of Clinical Periodontology) defines peri-implantitis as a plaque-associated condition, marked by inflammation of the peri-implant mucosa followed by progressive bone loss around the implant. A full-arch rehabilitation can therefore remain functional while developing this complication, which is why lifelong follow-up is warranted. The warning signs are described in Implant failure and peri-implantitis: signs to watch for.

# Technical complications: an often underestimated point

Beyond biological complications, a fixed full-arch prosthesis is subject to significant mechanical stress, and technical complications are common. This is one of the aspects least highlighted in commercial presentations of these treatments.

The review by Sailer et al. (2022, Periodontology 2000) recalls that technical complications cannot be entirely avoided with any implant prosthesis, and that patients who experience them are markedly less satisfied. For zirconia full-arch bridges, the systematic review by Bidra et al. (2017, European Journal of Oral Implantology) reports a low failure rate for the prosthesis itself in the short term (of the order of 1.4%), but prosthetic complications in around 16% of prostheses, most of which correspond to fractures of the ceramic veneer. Screw loosening or fracture and wear are also among the known hazards.

These complications can usually be repaired, especially when the prosthesis is screw-retained, but they have a cost and require appointments. Bruxism — grinding and clenching the teeth — increases these mechanical risks; its management is covered in Bruxism and teeth grinding: what to do.

# Day-to-day upkeep and hygiene

A fixed prosthesis is not taken out at night, which changes the hygiene routine. The patient must clean daily under and around the prosthesis, where plaque builds up, using interdental brushes, floss or suitable brushes, as the UFSBD patient information sheets point out. This hygiene is decisive, plaque being the central factor in peri-implantitis.

Professional follow-up matters just as much: regular check-ups make it possible to detect inflammation, a loosening screw or early bone loss, and to remove the screw-retained prosthesis for a thorough clean. A full-arch rehabilitation is not a device you fit and forget: its longevity depends largely on this upkeep over time. The principles of daily hygiene are detailed in Daily dental hygiene.

# An honest comparison with the removable denture

Faced with tooth loss, the choice often lies between a fixed implant solution and a removable denture, possibly stabilized on a few implants. Both have their place.

The fixed solution offers greater stability, is not taken out, and generally does a better job of restoring the feel of natural teeth. In return, it involves more extensive surgery, more implants, a higher cost and more demanding hygiene, since the prosthesis is not removed each day.

The implant-stabilized removable denture, conversely, requires fewer implants and is simpler to clean since it is taken out. This is the option that the 2002 McGill Consensus Statement placed as the first choice in the lower jaw, on the basis of trials showing better satisfaction, quality of life and nutrition than with a conventional, non-stabilized denture. It remains removable and covers more soft tissue, which some patients tolerate less well.

There is therefore no single answer. The right choice depends on the bone, general health, hygiene habits, expectations and means. Honest information presents both families with their advantages and their constraints.

# Limits and points to watch

To decide with full knowledge of the facts, several limits should be kept in mind:

• high survival rates relate to the populations studied and do not transfer mechanically to any given patient; survival in the upper jaw is generally lower than in the lower jaw;
• the survival of an implant or a prosthesis does not guarantee the absence of peri-implantitis or of mechanical complications;
• technical complications (ceramic fracture, screw loosening) are common and involve repairs over time;
• immediate loading requires sufficient primary stability, and the prosthesis fitted on the day of surgery remains temporary;
• daily upkeep and regular follow-up determine the long-term outlook, and no lifespan can be guaranteed.

Fixed full-arch rehabilitation on 4 to 6 implants is a well-established solution for giving fixed teeth back to someone who has lost their teeth or is about to, provided there is a thorough assessment, an indication suited to the arch concerned and follow-up over time. It is this careful, evidence-based framework that makes it possible to choose between this option and the alternatives, aware of both the benefits and the limits.