What the two concepts have in common

Both descend from the original Brånemark protocol, in which four to six implants were placed in the front of the jaw, between the nerve openings in the lower jaw or in front of the sinuses in the upper jaw, to carry a fixed bridge with molars cantilevered off the back (Resnik & Misch, 2018). The prosthesis is usually a hybrid: a milled titanium or zirconia framework carrying acrylic, composite or ceramic teeth, screwed to the implants so it can be removed for repair (Hupp et al., 2014). Acrylic hybrids are the easiest to repair, all-ceramic ones the hardest.

The All-on-4 logic: fewer implants, tilted at the back

All-on-4 places two implants upright at the front and tilts the two rear implants backwards by up to about 30 degrees. The tilt serves two purposes: it lets the rear implants stay in front of the sinus or the nerve, often avoiding grafting, and it moves the point of support further back, which shortens the cantilever behind it. In a toothless lower jaw a modest cantilever is often acceptable; the bridge may extend to roughly 1.5 times the front-to-back spread of the implants (Resnik & Misch, 2018; Hupp et al., 2014).

There is a physical price. Implants tolerate loads along their axis far better than off-axis loads: a load angled at only 12–15 degrees raises the force on the implant by around a quarter, and angles beyond 20 degrees magnify stress considerably (Hupp et al., 2014; Resnik & Misch, 2018). Angled implants with angled abutments “have been shown to be successful”, the complications textbook notes, but “surgical experience and case selection are crucial”. Four implants under twelve teeth also means the classic planning rules cannot all be met: there is no implant at the canine position and there are more than three false teeth in a row.

The All-on-6 logic: load distribution and a safety factor

Adding two implants changes the mathematics. In finite-element studies comparing six and four implants under a cantilevered full-arch bridge, six reduced stress at the implant-bone interface by 7 to 29 percent and distributed load more evenly across crowns, screws, cement and marginal bone (Resnik & Misch, 2018). The second argument is less about stress than about what happens when an implant fails. “There is no safety factor if an implant fails,” Misch writes; a worked example in the same chapter shows that if 20% of implants were lost, only 20% of patients with a four-implant fixed bridge would still have a working prosthesis, because losing any one implant compromises the whole design (Resnik & Misch, 2018). With six, the bridge can usually keep working on five while the site is treated.

The cost of this margin is bone: six implants need sites further back, which in the upper jaw often means a sinus lift. With less than 5 mm of bone under the sinus, grafting comes first and implants follow months later; with 5 mm or more and reasonably firm bone, graft and implants can go in together (Resnik & Misch, 2018).

Upper jaw or lower jaw: the single biggest factor

Bone at the back of the upper jaw is mostly of the softest type, described as 5–10 times weaker than the front of the lower jaw, and full-arch failure in the upper jaw runs at about three times the lower-jaw rate (Resnik & Misch, 2018). This is why the surgical textbook sets a minimum of four implants for a fully implant-supported lower-jaw prosthesis but recommends six for the upper jaw, and why Misch advises that an upper full-arch design should include a first-molar implant rather than relying on cantilevers behind the premolars (Hupp et al., 2014; Resnik & Misch, 2018). In our planning, a lower-jaw All-on-4 is a mainstream option; an upper-jaw All-on-4 is considered when the bone, bite and crown height genuinely allow it.

A decision table

In Misch’s framework, four implants between the nerve openings of the lower jaw support a fixed full arch only when force factors are low: no moderate or severe grinding, crown height under 15 mm and D2 bone (Resnik & Misch, 2018). When any of these is unfavourable, the answer is more implants rather than a stronger bridge.

Who is not a good candidate for either concept?

Relative barriers include severe parafunction, very tall crown heights, extremely soft upper-jaw bone, heavy smoking and uncontrolled systemic disease (Hupp et al., 2014; Resnik & Misch, 2018). Some of these can be managed, for instance with an occlusal guard, which the literature calls highly recommended for cantilevered hybrids under parafunction, or with longer healing in soft bone. Others lead us to recommend an implant-retained overdenture instead, which is easier to clean and repair for patients with limited dexterity (Hupp et al., 2014). Untreated gum disease around any remaining teeth is dealt with before surgery.

The provisional phase in both concepts

In suitable cases, each implant is tested during surgery: an insertion torque in the range of 32–40 Ncm and a resonance frequency value (ISQ) of roughly 55–85 are the thresholds cited for attaching a provisional bridge immediately (Resnik & Misch, 2018). If the thresholds are not met, the implants are left to heal under a removable provisional instead. The screwed-in provisional is a healing bridge with a softer diet and no cantilever load; the definitive bridge is made after osseointegration. Our page on the provisional bridge and the first months covers this phase in detail, and the immediate loading criteria page explains the stability measurements.

Visit plan for international patients

1. Pre-assessment via WhatsApp: a panoramic X-ray and photographs allow a preliminary opinion on four versus six and on the likelihood of grafting.
2. Visit 1 (generally 5–7 days): examination, CBCT, digital planning, extractions and implant surgery, provisional bridge within the first days if stability allows, bite adjustment and a check before departure.
3. Healing (generally 4–6 months, longer with grafting): remote check-ups with photographs.
4. Visit 2 (generally 7–10 days): impressions, framework try-in, tooth try-in, delivery of the definitive bridge and a baseline X-ray.

Risks and maintenance

Both concepts share the same complication family: screw loosening, acrylic or ceramic chipping, speech adaptation in the first weeks (reported in 4–8% of cases), and peri-implant disease (Resnik & Misch, 2018). Pooled survival of implant-supported fixed prostheses is around 95% at 5 years and 80% at 10 years, and hybrids need periodic refurbishment (Pjetursson et al., 2012). Maintenance visits are advised every 3–4 months in the first year with a radiograph at 6–8 months, then by risk; peri-implantitis affects a meaningful minority of implants over the years, which makes this schedule essential (Derks et al., 2016; Monje et al., 2016). See our implant aftercare page.

What determines the cost?

• Number of implants per jaw and the implant system.
• Framework and tooth material: acrylic hybrid, composite, layered or monolithic zirconia.
• Provisional bridge and whether immediate loading is possible.
• Additional surgery: extractions, sinus lift, bone reduction, grafting.
• One jaw or both.

A written fee follows the examination and CBCT; the structure of our fees and instalment options is on the prices and campaigns page.

Searching for the “best All-on-4 or All-on-6 in Istanbul”: what to check

• Does the offer explain why four or six, with reference to your jaw, bone density and bite?
• Is an upper-jaw All-on-4 justified on the CBCT, or is it a default?
• Is the same-day bridge clearly described as provisional?
• Is the framework material named, and is the bridge retrievable?
• Is a night guard and a maintenance schedule part of the plan?
• Who is responsible for follow-up if you live abroad?

Frequently asked questions

Related guides

Medical content review: Dr. Dt. Mehmet Fuat BozabaHead physician, works in periodontology and oral surgery · Last updated: October 2026 · About the head physician

Contact: Yayla Dental Akademi, Ferit Selimpaşa Cad. No:44A, Bahçelievler, Istanbul (Basın Sitesi, opposite Migros; about 600 m from İlkyuva metro station). Monday–Saturday 10:00–21:00, Sunday closed. WhatsApp and phone: +90 544 289 66 33 · Online booking: DoktorTakvimi.

Sources

This page is for information only; diagnosis and treatment plans are determined by a dentist after an examination. Survival figures are population averages from the cited sources and do not describe an individual outcome.