The number one problem that becomes an obstruction to dental implantation is bone tissue atrophy. However, with a reservation, besides the classical method, a number of dentists today offer prosthesis implants methods to patients without the necessity of increasing the jawbone. We're now talking about the All-on-4 and All-on-6 dental Implants protocols. These methods are alternatives in cases where it is necessary to remove some of the removable dentures that are completely edentulous or living teeth in poor condition.


All-on-4 dental Implants technology is a patented development of the American-Swiss company Nobel, which has been manufacturing dental implants of the same name for more than half a century. Prostheses on the six implants are actually the new generation because the development of this technique has taken into account the disadvantages and shortcomings of the “four” technologies.

Both methods are used in the presence of atrophied bone tissue and imply immediate loading of the prosthesis.

Now, we will try to understand the pros and cons of each method and why it is not so common in our country - the lack of skills, short life or other disadvantages.

All 4 Dental Implants


As mentioned earlier, this development belongs to Nobel, the first company in the world to collaborate with the developer of dental implants (Dr. Brannemark) and put the products into mass production.

Interesting “For the first time in practice, the Portuguese implantologist Paulo Malo performed the All-on-4 treatment concept in 1998. First, the doctor worked in solitary confinement, but later his development was purchased by Nobel in 2004 when he introduced this concept of treatment.”

The concept of prosthesis on four implants is more common in Europe and the USA than in our country. This can be explained by the fact that the implantologist must undergo lots of compulsory training and obtain a certificate from Nobel for the right to work with this protocol.

It should be noted that Nobel products are one of the most expensive ones, and that is one of the reasons why doctors are not in a hurry to get the appropriate certificates - there will be a small demand for implants, and implantologists themselves often do not have the opportunity to undergo appropriate, very expensive training.

Therefore, the main features of All-on-4 prosthesis technology are as follows;

Only 4 dental implants are used for prostheses of all teeth

2 implants fixed in lateral areas (between the fifth and sixth teeth), the other 2 vertically fixed in place of the anterior teeth

The prosthesis is installed instantly, not on another day, not after an hour, just after implantation

During the application of all-on-4 technology, implantation is achieved by absorbing weak or moderate bone with sufficient bone tissue.

Conventionally implants are two-piece structures, but a multi-unit abutment is designed to be fully utilized on a particular inclination of the implants. So after the connection, the abutment achieves a completely vertical position.

Computerized 3D modelling being used in all stages of treatment

Now we will examine each item in more detail in terms of the advantages and disadvantages identified by the implantologists applying this system.

Implant Types and Installation Characteristics

Specialists use two-piece implants with screw design when using the All-on-4 prosthesis technique. These are actually classic root-shaped models made of pure titanium and equipped with a special porous TiUnite coating. It is a hard layer of titanium oxide with the high phosphorus content. This significantly accelerates the osseointegration process, in other words, the association of bone and implant.

Such implants are also placed in a conventional (patchwork) manner. After starting anaesthesia, the gums are cut, removed from the bone tissue, formed in a bed bone under the implant (cut with the help of boron), and gum is stitched up after implant placement.

Important!“The inclined mounting of the lateral implants makes it possible to the implant, for example, bypassing the major nervous system nerves, such as the maxillary nerves and the nasal sinuses. In addition, it is possible to place the implants more accurately in the alveolar projection and to optimally distribute the load to them. The slope of the "screws" on the side allows you to increase the contact area between the implant and the bone, thereby creating full support for the prosthesis.”

The abutment is fixed on the implant. Inclined abutments (multi-unit) are also selected for inclined implants. Therefore, the position of the upper portions of the implant on the gum is aligned and the prosthesis is fixed in a completely flat manner without disturbing the patient's occlusion and bite.

Really Necessary to Make a Bone When Using All-on-4 Technology?

The all-on-4 concept is used for mild to moderate bone tissue atrophy:

On the upper jaw - at least 5 mm wide and 10 mm high

On the lower jaw - at least 5 mm wide and 8 mm high.

The oblique position of the implants allows you to select sites with a thicker bone of sufficient volume so that bone tissue atrophy can be treated.

An important feature of the all-on-4 prosthesis method is that its application is confirmed only by mild atrophy of the jaw, not by significant resorption.

Dentist's Opinion

“All-on-4 is undoubtedly one of the best technologies designed for patients with adentia. But only moderate and light. The concept suggests that the primary degree of fixation of the implants should be at least 35 Newton, which cannot be achieved in the presence of significant bone atrophy. When the lateral implants were moved a little forward or backward according to the proposed location according to the protocol (due to lack of space), I had to follow my colleagues' work repeatedly. A few years later, this caused the entire system to collapse completely because part of the bone continued to atrophy due to lack of load.”

Another point concerning the condition of the bone tissue is the implantation at the same time as the removal of the diseased teeth. In the classical approach, the healing of bone tissue takes some time (usually 3-4 months) and only after that it is possible to perform implantation. All-on-4 with dental prosthesis technology, the situation is similar, in principle, only the protocol developer recommends installing implants next to it.

Prosthetic PropertiesAccording to the original All-on-4 protocol, the prosthesis is mounted simultaneously with fixed acrylic bridge implants. It waited for a period of several months (about six months), so you should wear it until the implants merge with the bone. The option to relocate a removable denture that was previously worn by the patient is also allowed.

Important!The patient should be prepared for the fact that the prosthesis will be made with an acrylic base - some kind of artificial gum. Its use can be explained by the fact that it is necessary to “cover ın the defects of the mucous membranes of its own because it has a very aesthetic appearance due to the long absence of teeth. Plastic surgery is expensive and difficult for the whole treatment in terms of patient rehabilitation. Therefore, such an option has been proposed.

Instant prostheses (immediately after implants are fixed) follow several targets simultaneously;All-on-4 prostheses stabilize implants. They are joined between them by a metal beam which allows them to be fixed in a certain position. This is fully possible in the absence of all teeth (if you are installing only one implant, it will change under pressure)The prosthesis transmits the load to the bone. A person's jawbone must take the pressure - it is physiological because the cells feed this way. When the chewing load is restored within the bone, natural processes are activated and regeneration is faster (the volume of the bone is gradually restored).The prosthesis allows the patient to regain his aesthetics and ability to eat completely.A gradual increase in chewing load occurs in the months after implantation


According to the original All-on-4 prosthesis technique, the prostheses are assembled on the day the implants are fixed. From the patient's point of view, that's great news, because you're leaving the doctor's office with new teeth. However, in practice, the installation of the prosthesis is better for establishing crowns at least one day after surgery. After the implants are fixed, the sutures are placed and the gums are injured. It takes some time to rehabilitate them. Otherwise, there will be pain and there is also a high risk of inflammation of the mucous membranes."

Process Simulation

Nobel is known for its innovative approach to treatment. After consulting the doctor for the first time, medical or conical ray tomography is performed. The data obtained are downloaded to a computer and the whole process is simulated in a three-dimensional with the help of special software (Nobel Guide).The doctor creates a virtual model of the jaw and determines the volume of the bone and the location of all important anatomical structures. The program helps to select a place for implantation and then develops surgical templates that help to establish without shifting shafts even a millimetre.Proper treatment planning eliminates “human” errors. In addition, the patient himself can evaluate the final outcome of the prosthesis.

Is There Any Negativity?

“All-on-4” implantation has very few defects if it is performed strictly in accordance with the original treatment protocol. First, there is a risk of inflammation of the mucous membranes because the prostheses are fixed in the original technique within the same day of implant placement. For the patient, on the one hand, this is a plus, because he regains his aesthetic at the same time. However, in practice, the injured gums react with inflammation. The problem is solved by fixing the prosthesis 2-3 days after the operation.

In addition, experts note that when the volume of the jaw bone of for four implants is insufficient, the bone does not take the correct load and the atrophy continues. Resulting in the frequent displacement of the prosthesis and possibly slipping of the implants.

Another disadvantage of all-on-4 prostheses is related to bone tissue. A bed is formed with the help of boron to attach the implant to the bone tissue. At the same time, a portion of the saw-treated bone is removed from the hole and, in fact, under the conditions of atrophy, the patient's own bone material is actually "equal to the gold value of its weight". For comparison: With the All-on-6 technology, which will be discussed further, the implants are screwed to the bone and no bone loss. On the contrary, they are clamped around the implant tooth, which contributes to better fixation.

Can I Do All-On-4 Prostheses On Other Implants?

Patient evaluation of all-on-4 prostheses:“I'm 64, I've worn removable dentures for a long time, but I got tired. I am a very active person, I travel a lot, I love cooking. I have applied to several clinics, but the duration of treatment is unacceptable to me. I found a few prosthetic variants. Carefully studied. Nobel is safe. Implants quickly installed to the bone and sutured at the same time. There were dietary restrictions in the first months, but after six months I replaced the prostheses with dioxide and enjoyed life. The operation was done about 3 years ago and so far my teeth make me happy, no complaints at all. "

About the All-on-6 Prosthesis Method

The concept of prosthesis All-on-6 was developed by practitioners based on the application of technology on four implants and considering the experience of use. basal implantation. The protocol was performed using six implants.

Unlike all-on-4, treatment indications have been extended: prostheses are performed with atrophy of middle bone tissue, as well as with periodontitis, periodontal disease or jaw osteomyelitis. Smoking is not a contraindication.

In general, the two technologies are similar - the similarities and differences of the specified protocols will be presented below.

Firstly, let us mention the distinctive features of the All-on-6 prosthesis protocol:1. 6 dental implants are used for the prosthesis of all teeth (4 implants are fixed vertically in the lateral and 2 other - frontal regions)2. The prosthesis is installed 2-3 days after implantation3. All-on-6 implantation is performed with moderate or severe bone resorption4. The angle of the implants is selected individually and after implanting the screws adjustable abutment is fixed on the screws as one piece.5. Implant placement is possible at the same time as the teeth are removed, and “screws can be mounted in the same hole6. All-on-6 prosthesis technology is a more economical solution than conventional implantation and original technique than All-on-4

Implant Types and Installation Characteristics

The All-on-6 method uses essentially different implant models rather than using All-on-4 technology.

One-piece implants; the abutment and intraosseous parts are a single whole. After installation, the abutment can be bitten and aligned according to the position of the prosthesis.

The implants are fixed in a minimally invasive way - they are fully screwed into the bone, the gums are not shed, and the sutures after surgery do not overlap. This means that the patient heals faster.

The implants are placed at one certain angle. Like the All-on-4 use of technology, this approach allows you to, select the most durable parts of the bone, and not hurt the nerves and nasal sinuses.

Isn't it Really Necessary to Build a Bone with All-on-6 Prostheses?

The designs of the implants used are designed in such a way that fixation is possible not only in the alveolar (spongy) part of the bone but also in the deeper parts. These are the basal layer, the shell of the cortical plate or bone, as well as the jawbone and the jaw buttresses (strength lines).

The most "soft" bone layer - the centre (spongy) 90% consists of capillaries. In the absence of teeth, the metabolic processes in the bone posture, that is, above all, the spongy piece that suffers, shrinks significantly in volume. The remaining parts are made of bone septum - more durable, with fewer capillaries in them, or absent completely, and atrophy is not obvious here. Therefore, for immediate loading, the implants will contain these layers first.

Due to the fixation of the implants to the dense parts of the bone, the strength of the primary stability is 80-100 newton, whereas in conventional implantation this figure ranges from 30-40 Newton.

Similarities Between the Two Technologies

The main similarity of the two methods is the possibility of immediate fixation of a prosthesis. And the immediate purpose of inserting the crowns is exactly the same - loading the bone, restoring the aesthetics and functionality of the tooth, and stabilizing the inserted implants. In both cases, the prostheses are formed with an artificial gum to conceal the uneven contour of the natural mucosa.

Patient prosthesis examination on six implants:

I have been sceptical for a long time when choosing this method. It was embarrassing that the prosthesis changed over time and had a plastic gum. After all, the same removable denture pulls out! The doctors showed the pictures, but the photo is the one thing, the other one in real life. Long thought but decided, the price is very attractive. As a result, after the implants were placed, there was almost no pain, only slight discomfort after the tooth was extracted. The prostheses were placed on day 3, because it was much more comfortable than the removable ones, it didn't take long to get used to them! When they change, they look fine! "

Computer modelling is also used when planning dental prostheses in the all-on-6 method. Modern technologies ensure complete operation throughout the entire treatment process to avoid errors in the installation of implants.

What are the disadvantages of technology?

All-on-6 prosthesis technology emerged later than All-on-4, so its development took into account the main drawbacks of the protocol. This method brings high demands on the skills of the attending physician: a jaw surgeon must be an orthopedist and be competent to work with software for 3D modelling of the treatment process. must have full knowledge of the structure and operation of the maxillary system (not only does it have to place implants in a narrow and thin bone, but you must also accurately calculate the load on them and the prosthesis must be adapted for several years without breakage and comfort for the patient. Which method comparing the two technologies?

To sum up, the All-on-6 prostheses are one step ahead compared to the technology using only four “screws. Or two installations, judging by the number of implants to be placed. However, the use of each technique depends on the specific conditions of the jaw bone. All-on 6 does not need to be administered with sufficient bone tissue and, in contrast, the All-on 4 is ineffective with poor quality of the bone structure. Therefore, only the interested physician should choose the prosthesis method based on the results of clinical and computer examination of the oral cavity and jaw bone.

DDS PhD Özkan Özkaynak
Article written by
DDS PhD Özkan Özkaynak