Fixed implant-supported prostheses for edentulous arches have become increasingly relevant in contemporary clinical practice. All-on-4 and All-on-6 are the two most recognized variations of this concept. Both aim to deliver a full-arch fixed restoration on a single jaw; the principal differences relate to implant number and the indication nuances that follow. The overall concept is described in detail on the All-on-X page.

What Is All-on-4?

All-on-4 refers to the placement of four implants at strategic angulations in an edentulous arch, supporting a fixed prosthetic restoration. The two posterior implants are typically positioned at an angle, an approach intended to reduce the need to engage the maxillary sinus or mandibular nerve regions.

What Is All-on-6?

All-on-6 applies the same principle with six implants. The two additional implants allow load distribution across a wider base. This configuration may be preferred in patients with higher masticatory load or when bone conditions are favorable.

Indication Criteria

Several factors are considered when deciding between the two systems:

Volume and quality of the alveolar bone
Status of the opposing arch (dentate, partially dentate, edentulous)
Masticatory load and occlusal relationships
Systemic condition and healing capacity
Width of the planned prosthetic design

In cases with limited bone volume, low sinus floor or where additional surgical interventions should be avoided, the All-on-4 approach is often favored. When bone conditions are favorable and load distribution across a wider base is desired, All-on-6 may be considered.

Surgical and Prosthetic Stages

In both systems, the process begins with clinical examination, three-dimensional imaging and digital planning. Implant positions and angulations are determined during planning. Following the postsurgical healing period, the prosthetic phase begins. The provisional and final prosthesis designs vary by case. Details of the prosthetic stage are covered on the implant-supported restorations page.

The Decision Is Multifactorial

Implant number alone does not determine clinical success. Placement angles, bone quality, occlusal load balance, prosthetic design and recall compliance ultimately shape the outcome. Different approaches are not applied to separate regions of the same arch; the system is selected as a whole.

Evaluation Process

Initial assessment combines clinical examination with panoramic and three-dimensional imaging (CBCT). Bone volume, sinus status and anatomical landmarks are reviewed. Findings are interpreted together to identify the suitable system. The overarching aim is a functional and sustainable restoration over the long term.

The All-on-X page summarizes the indications and process steps for both systems.

The appropriate system is determined through clinical assessment and imaging; consulting a dental professional is recommended.

Dr. Dt. Busra Kaya, Specialist in Prosthodontics, Atasehir Istanbul.

All-on-4 vs All-on-6: Clinical Differences