When doing a full set replacement and using multiple fixtures to support the prosthesis, or replacement teeth, there is a distinct physical advantage when these posts are linked together. Apart from providing more supports for the prosthesis, the rigid cross-arch fixation of the implants through the prosthesis itself results in the distribution of functional pressures between the implants and sharing of the loads, and thus the pressures to each fixture individually are greatly reduced, allowing them to adapt or integrate with the bone without disturbance. This is known generally as a biomechanical advantage.

In addition to the biomechanical advantage, there was also the consideration that replacement of a single tooth is certainly not as significant as replacement of a full set for patients debilitated by their dentures or tooth loss. Thus the functional significance of treating edentulous ‘oral invalids’ when coupled with the biomechanical advantage of using multiple fixtures for support meant a highly favourable risk-to-benefit ratio and sound overall prospects of success unaffected by certain single individual fixture losses.

Following the early work and proven clinical applications of Dental Implants, this area has been expanding ever since, to the point where osseointegration has become the single most researched topic in dentistry of all time. Today the use of dental implants in everyday practice has become routine and the standard of care. In 2004 the American Dental Association has reported that “the average survival rates of multiple implant designs placed in various clinical situations are more than 90%”. They also reported findings that implants may provide a “more predictable outcome” than alternative therapies [Stanford C, Rubenstein J. Dental endosseous implants-an update. ADA Council on Scientific Affairs. Journal of the Americal Dental Association 2004; 135:92-95]. A review of some of the current literature suggests survival rates in the vicinity of 97% to 98.5%. These figures are more favourable than almost any other day-to-day procedure we perform. But how reliable are these figures? Is survival (or osseointegration) of the implants enough?

Watch Professor Branemark who discovered osseointegration apeak at a dental conference in Sweden in 2012.

We have long passed the development phase of implant therapy where restoring function and ensuring that the dental implants ‘survive’ were central. In today’s society, these criteria alone are no longer acceptable on their own. Function, aesthetics and long-term oral health parameters must all go hand in hand as implant ‘Survival’ is not necessarily synonymous with Implant ‘Success’, just as a cosmetic procedure is not necessarily an aesthetic one.

We know that dental implants osseointegrate and do ‘survive’ in the vast majority of cases. But the results may often be overshadowed by a complex treatment process, poor aesthetics, difficult cleaning regimes, among other issues. This led to the need of subsequent generations of dental professionals and opinion leaders, included among those the team at the All-On-4 Clinic, to shift the focus from ‘implant survival’ to ‘case success’, and from the dental implants treatment itself to the consideration of the patient as person and an individual. We had to make dental implants successful by today’s standards, and for today’s patients in an era of ‘high aesthetics’ and ‘immediate’ needs.

In the last decade the trend with the number of fixtures used to support a prosthesis replacing a full arch has been to use less and less dental implants. At the same time, the trend has also been to eliminate the healing phase and to immediately load them. In doing so, are we pushing the limits, or simply providing the product of evolution in this field? The answer is certainly evolution, and the various aspects pertaining to it are outlined in the paragraphs below:

In the past we used to place 6 to 12 fixtures to support the prosthesis. We did so because we were worried that if one or two fixtures failed, there would still be others left to support the prosthesis. However over time we have come to realize that one of the major reasons for implant failures was inadequate hygiene, and it was not because the patient did not try to clean properly, just that they were unable to.

Dental Implants are placed in the jawbone, and when the prosthesis is attached to those fixtures they become submerged and it is difficult to locate their position. As such, the more fixtures present the more difficult it is for the patient to know how to clean around the gum interfaces. It follows that the less effective the cleaning the higher is the chance for infections of the implants or eventual failure.

When using only four fixtures, such as the case with the All-On-4 procedure, there are 2 fixtures in the front and 2 in the back of the jaw. This means that it is simpler to locate their positions, even though they are submerged, which makes the hygiene substantially more effective, and in turn leads to improved success.

Biomechanically we know that 4 implants is certainly enough in the vast majority of clinical situations, but there are cases where there is an imbalance between the forces at play during function, and the resistance of the implant system to withstand them. An example is when the bite is very strong, such as in those who grind their teeth heavily, leading to increased forces at play (loading of the fixtures), and/or when the bone is of a very poor quality leading to reduced stability or capacity of the implants to withstand the functional loads. In such situations, there may be a need to increase the number of dental implants for long-term support.

A feature of All-On-Four treatment is the placement of the back implants at an intended angle.

Numerous clinicians at about the same time in the 80’s and 90’s in an attempt to avoid certain anatomical limitations typically seen in the back of the upper and lower jaws have successfully avoided bone-deficient areas with the use of angulated implants. Anatomical limitations are more prevalent in patients with full dentures, and once the back implants are placed at an angle there is often only enough room left for two more implants in the front. This has lead to the use of only four fixtures to support a full set of teeth.

The concept itself of a full set of teeth supported by as few as four fixtures was not a new one. Even Dr Branemark, who discovered osseointegration published numerous articles in the 70’s with successful rehabilitation of a full arch supported by this number of fixtures. However it was the angulation of the back implants that has lead to today’s All-On-4, and has been trialed by numerous clinicians simultaneously in the USA, Sweden, Portugal, and South America in the 1990’s. In Australia the concept did not take off until 2005. Dr Alex Fibishenko was one of the early pioneers of the treatment at the All-On-4 Clinic Melbourne, and made further modifications to the process with various clinical innovations to enhance the outcomes and patient experiences.

The original All-On-4 concept was not initially popular with opinion leaders in Australia because of the limited contingency of this treatment. Thus the concern was that there was no Plan B if a single implant failed. The introduction of All-On-4-Plus by Dr Fibishenko, which offered, among innovative surgical and restorative techniques, improved contingency and a streamlined process, and has led to an exponential rise in popularity even of this treatment in Australia.

In the past we used to try and preserve or build up the bone that had been lost through trauma or natural bone atrophy which occurs following the loss of teeth in preparation for the placement of dental implants. However, whilst these procedures are quite predictable in terms of creating a bed into which to place fixture, they are far less predictable in actually achieving a natural choreography of the gums, leading more often than not to poor appearance by our standards.

In addition, building up the bone caused a reduction in the space available for the teeth themselves, which were to be replaced, and apart from poor aesthetics, the strength of the bridge that was fitted to the implants was compromised.

To attain a high level of aesthetics, one of the important steps included in our All-On-4 Plus treatment is the re-shaping of the jawbone by flattening the uneven parts of the residual bone once the teeth are removed. This procedure has a number of important benefits:

• It allows for a flatter interface under the bridge which, when compared to a rugged interface of older methods, further simplifies the cleaning process
• It allows for Aesthetic Gum Replacement, where in essence that the gum section becomes part of the prosthesis. As such the final appearance and choreography of the gums can be designed and controlled by our technicians leading to a more predictable aesthetic outcome
• The additional space created allows for an improved design of the restoration aimed for better aesthetics, improved comfort and more durable restorations

In the past we used to do the dental implant procedure in two stages. We started by placing the fixtures in the bone, we would then allowed them to heal for 4-6 months, after which time we would commence the process of making the prosthesis that would ultimately attach to those fixtures.

However, the problem was that during the healing period the patient would wear a denture as an interim prosthesis. This denture, as we have come to learn over time, would impart pressures on the implants in an uncontrolled manner, thus disturbing their adaptation with the bone.

Below is some of the literature that has lead to us moving away from a 2-stage approach where the patient would wear a denture in the interim:

• Brunski JB. Avoid pitfalls of overloading and micromotion of intraosseous implants. Dental Implantology Update 1993; 4:77-81
• Szmukler-Moncler S, Salama H, Reingewirtz Y, Dubruille JH. Timing of loading and effect of micromotion on bone dental implant interface: Review of experimental literature. Journal of Biomedical Materials Research 1998; 43;192-203
• Esposito M, Thomsen P, Ericson LE, Lekholm U. Histopathologic observations on early oral implant failures. The International Journal of Oral and Maxillofacial Implants 1999; 14:798-810
• Pilliar RM, Lee JM, Maniatopoulos C. Observations on the effect of movement on bone ingrowth into porous-surfaced implants. Clinical Orthopaedics 1986 July; 208:108-113
• Baumgarten HS, Chiche GJ. Diagnosis and evaluation of complications and failures associated with osseointegrated implants. Compendium 1995; 8:814-823
• Deem LP, Bassiouny MA, Deem TE. The sequential failure of osseointegrated submerged implants. Implant Dentistry 2002; 11(3):243-248

Today the teeth are attached to the dental implants within days of their placement, such as the case with All-On-4 Plus treatment. The reason this works is because the implants are attached to each other through the prosthesis, and they share the load through cross-arch stabilization, rather than individually being subjected to loading from a loose denture. However, in all such treatments the patients are asked to maintain a softer diet for the initial period of healing so as to avoid excessive pressures or disturbance in the adaptation of the implants.

Unfortunately in Australia, there is no registerable specialty dedicated to Dental Implants. As such training paths vary for dentists and specialists who wish to undertake dental implants work. However, this field is nevertheless highly specialized and requires that the surgeon who places the implants have an intimate understanding of the restorative requirements, and vice versa for the restorative dentist. The emergence of practitioners who possess experience in both disciplines, such as the surgical clinicians of All-On-4 Clinic, is advantageous for patients not only for their insight but also for a streamlined process and being able to have all stages of treatment done in the one clinic.

Implant treatment is not simple to undo, and it is important that clinicians attain experience in a gradual manner before proceeding with advanced treatments such as All-On-4 Plus and Zygoma Plus. Unfortunately, due to the potentially implied simplicity of these procedures, certain clinicians may be attracted to these more complex treatments before having sufficient experience in other related areas.

Dextrous capability and cross-disciplinary knowledge and skills are important in implant therapy, but these are secondary to sound treatment planning. Treatment planning is often reliant on your dentist’s awareness. So whilst finding a clinician with advanced skills and experience that would make them capable to deliver success with advanced treatments such as All-On-4, it is your regular dentist who may play a vital role in discussing your options. And the only way that clinicians can better familiarize themselves with new methods is through continued training and education, which are provided at the various All-On-4 Clinics throughout Australia in Melbourne, Sydney, and Brisbane, Perth, as well as public information seminars where our dentist colleagues are also welcome.

As clinicians in the era of ‘aesthetics and high expectations, we must always think beyond the square, beyond the ‘teeth’ or ‘implants’. Patients do not want implants. What they want is a beautiful smile, normal function, and uncomplicated options in the event of an unforeseen. The quality of our treatment planning is in the end judged by our ability to synchronize what is possible with what is practical and predictable; as well as our ability to draw on what we know, concur what we still don’t know, and be mindful of that which we don’t know that we don’t know.

For more information about Dental Implants and All-On-4, or to ascertain your suitability for these procedures, call the clinic on 1300 255 664 (1300 ALL ON 4).