All-on-4 vs conventional dental implant treatment in Singapore

Many years ago, a patient for whom I was planning a full mouth dental implant treatment in Singapore commented that it cost more than his double by-pass surgery which he had just undergone the year before. Another full mouth implant patient put it in a lighter tone, saying it is like stuffing a BMW into his mouth. Yes, dental implant treatment is expensive. As such, dentists and implant manufacturers alike have been trying different approaches to bring down the cost. However, it is a tough balancing act, trying to bring cost down and maintaining high standards. The All-on-four protocol is one such approach and up to this point, it is proving to be rather successful. Can it replace the conventional approach altogether? Probably not. 

There are reasons why full arch implant treatment is so expensive.

1. Adjunctive Procedures

In Singapore, most of the patients presenting for full mouth implants have lost their natural teeth for many years and have been wearing removable dentures. The long years of having no teeth coupled with pressure from a denture lead to significant bone resorption, leaving insufficient bone to support dental implants. As such, these patients require adjunctive procedures such as bone and soft tissue augmentation. All these adds to the already high cost of dental implant treatment. As with all surgeries, there is a possibility of complications which will require more time and resources to managed. Such a complex array of procedures is a recipe for skyrocketing cost.

2. Rising aesthetic demands

Another reason for the high cost of full arch restoration is rising expectation of the patient and dentist. In the early years of modern implant dentistry, success of osseointegration was equated with success, period. When I first started doing dental implants 24 years ago, oral surgeons drive the treatment plan. Back then, the oral surgeon will find the sites with the best bone and place the implant there. Our job was to ensure that the implant has the best chance of integrating. Once integrated, the prosthodontist will have to figure out a way to use them to support a prosthesis. Today, the prevailing thinking of implant success is the survival of an aesthetic prosthesis. Once osseointegration became predictably achieved, the philosophy shifted to one that is prosthodontically driven. The prosthodontists argue that patients want teeth, and the implants are just there to support the teeth. This spawn an era of extensive pre-implant surgery, to convert every case to a case with ideal hard and soft tissue anatomy prior to implant placement and if necessary, further refinement surgery post-insertion.

Novum: beginning of simplification of treatment..

At some point, alternative protocols have been proposed. The late P I Branemark, father of modern implant dentistry, once proposed a less expensive solution all the Branemark Novum. He rationalized that cost has spiraled out of control because of extensive individualization of treatment plan. He created a protocol of using pre-fabricated components and adjusting the patient’s jaw anatomy to fit one of three pre-determined sizes. Using only three implants splinted together with a pre-fabricated framework, a full arch fixed prosthesis is supported. This protocol was not successful and was withdrawn from the market within a few short years.

All-on-4:

This is yet another protocol that seeks to simplify and reduce cost for patients who need full arch implant supported fixed prostheses. Unlike the Novum technique, this does not require trimming of the jaw to fit any pre-fabricated parts. It relies instead on the biomechanical research that showed that an implant can be loaded non-axially without any problem. This paves the way back to the old days where we place the implants in positions where the bone is abundant but not necessarily in an axial direction that is ideal for implant insertion.

Avoiding the maxillary sinus...

In the upper jaw, the area that tends to have the fastest bone resorption is at the back, due to the expansion of the maxillary sinus downwards after tooth loss. As such, conventional implant therapy often requires sinus bone grafting to rebuild the lost bone. If the patient has a removable denture, the front of the upper jaw also tends to resorb due to pressure exerted through the gum. However, within the upper jaw, there are struts of bone that are better able to withstand these forces. It is the bony buttresses lining the side walls of the nose and maxillary sinuses respectfully. However, these buttresses are aligned at diverse angles to each other, making restoration difficult. In recognition of this difficulty, implants are placed in such a way to engage the maximum amout of buttress bone. Special angulated abutments are manufactured that can correct the angulation of the implant abutment such that they are all aligned parallel to each other and somewhat perpendicular to the jaw. This will allow the placement of four implant supported screw-retained prosthesis. This protocol has been around for ten years and been validated by several other research groups. Its success rate is not different from axially loaded implants. The All-on-4 protocol seeks to avoid having a sinus bone graft thereby saving time and cost.

Avoiding the mandibular nerve...

In the lower jaw, implant placement at the back is often constrained by a nerve that runs in the back of the lower jaw, exiting in the region of the premolar. Implant placement can be done in the front of the jaw, in front of the exit point of the nerve, but tilted towards the back so as to extend the spread of the implants to support a full arch prosthesis. By avoiding implant placement at the back, adjunctive procedures such as bone grafting, distraction osteogenesis or nerve transposition is avoided, thereby saving cost.

Disadvantages of All-on-4:

1. Lack of contingency:

However, while substantial cost may be saved, having only four implants to support a full arch prosthesis leave no room for implant failure. If one implant were to fail, the remaining three implants may not be able to support the prosthesis in the long run. If a replacement implant is placed, the prosthesis will need to be remade, and that can be expensive. Compared with the traditional approach of over-engineering the support for a full arch prosthesis with bone grafting and 6 to 10 implants, the All-on-4 protocol does not have much room for contingency.

2. Screw loosening and breakages:

Angulating the implants to engage maximum bone to implant contact means that angulated abutments are needed to compensate for the implant angulation. The prosthesis that is screwed onto these abutments have shorter screws than when engaging directly onto the implants and may be more prone to loosening and breakage.

3. Prosthesis Aesthetics:

Aesthetics may sometimes be compromised due to the angulation of the implant creating unsightly bulks in some parts. In cases whereby the upper jaw is severely retruded compared to the lower jaw due to excessive bone resorption, the prosthesis may have to be made in such as way as to have an extension beyond the bone to achieve a proper bite. This may render home maintenance more challenging but yet oral hygiene is even more essential for All-on-4 due to the under-engineering philosophy.

Which is better?

If money is no object, is the All-on-4 the treatment plan of choice? Proponents say yes but I am not absolutely convinced. It is good value for money as it is less than half the cost of what traditional plans require but deliver 80% of the results. However, for the patient with more exacting demands and can afford it, All-on-4 cannot deliver. Like cars, a humble Hyundai will get you from point A to point B. But if you want to travel in luxury, be protected by all known contraptions invented by man and arrive in style, a Rolls Royce is what you need but will cost you many times more. Similarly, in implant dentistry, one can choose the Hyundai plans, the BMW plans, or the Rolls Royce plans.