This concept was introduced by Nobel Biocare, Sweden. But what is an all‐on‐4 technique? Who should consider it? Is it considered safe? And how is it different from common implants?

Nobel Biocare presented this treatment as a means of overcoming limitations in the human mandible. This  treatment  is basically  immediate‐function protocols involving   the use  of dental  implant supported prostheses for the rehabilitation of completely edentulous mandibles and  are documented as having a high success rates.

The loss of alveolar bone with a relative surfacing of the inferior alveolar nerve in the mandible is a result of posterior teeth loss, particularly at an early age, thus often prohibiting placement of implants in the posterior  regions.  An  alternative  could  be  the  use  of  tilted  implants, which  allows  for  maximum  use  of  the  existing  bone  and  placement  of  posterior  fixed  teeth  with  minimum  cantilevers  in  a  region  where bone height and nerve proximity does not allow for the placement of axial implants.

In this  treatment,  only  4  implants  are  utilized.  Two are placed  vertically  in  the  anterior  and  the  other  two placed with an angle up to 45 degrees in the posterior region. Unlike other implants, multi‐unit abutments are placed and can provide  soon-to-be  edentulous  patients  with  an  immediate  restoration.

Based  on  the  optimal  number  of  four  implants  for  supporting  full‐arch  prosthesis  in  an  edentulous  jaw, the concept benefits from the posterior tilting of the two distal implants with a maximum of a two tooth distal cantilever in the final prosthesis. Optimized bone support with minimum bone volume is provided in  this  treatment.

With this said,  these  are  not  the  only  benefits  as improved  anchorage along with  vital  structures  avoidance  (such  as  mandibular  nerve  or  the  maxilla sinus)  are  also results of the tilting  of implants in the maxilla optimizing  load distribution and allowing for a  final  prosthesis  with  up   to  12 teeth. One can  conclude  that there  is  a clear biomechanical  advantage  in  using  splinted  tilted  distal  implants,  rather  than   axial  implants, supporting distal cantilever teeth.

The step by step procedure of the treatment.

The first step of the procedure includes:

Wax Try‐in Denture /Re‐mount and Equilibration/ Cross  Mount  and   Occlusal  Guide /  Bite Registration /  Duplicate  Denture  and    Surgical  Template/  Adding ٠30-45  Degree Angulation for Posterior Implant, Indication of the Amount of Ridge Reduction and Marking the Surgical Template.

The  second  step  involves:

Marking Vertical  Dimension  of  Occlusion  prior  to   Surgery/  teeth extraction / dental implant placement /  Attachment of Multi‐Unit Abutments / Index position of Multi‐Unit Abutments /   Hollowing‐out  space  in  denture  for Temporary  Coping  Multi‐unit /  Attaching  Temporary Coping  Multi‐unit  to  Multi‐Unit  Abutments /  Reducing  the  Height of  Temporary  Coping  Multi‐Unit / Rubber Dam attachment / Picking‐up Temporary Coping Multi‐unit cylinders / Removing Prosthesis with Temporary  Coping  Multi‐unit  cylinders  processed  in  acrylic /  Converting  from  Immediate  Denture  to Fixed Implant Bridge / Polishing and Smoothing the Surface of Fixed Implant Bridge   and finally Attaching Provisional  Fixed Implant Bridge Prosthesis with Prosthetic Screws.

In a research done on 245 patients with a total of 980 immediate‐function implants (four per patient) placed in the anterior region to support fixed full‐arch mandibular prostheses. The results were as follows: a total of 21 implants failed in 13 patients, giving cumulative patient‐related and implant‐related success rates of 94.8% and 98.1%, respectively, at  five years, and 93.8% and 94.8%, respectively, with up to 10 years of follow‐up. The prostheses’ survival rate was 99.2%  with up to 10  years  of  follow   up.

These   results  support  the  conclusion  that  the  All‐on‐4 immediate‐function  implant  concept is viable and a patient friendly long term stable treatment.