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Q&A for Dental Professionals

  1. The Evolution of the All-on-4® Treatment Concept

Prosthodontist emphasizing dental implants, restorative, reconstructive and cosmetic dentistry
Dr. Paulo Malo, the inventor of the All-on-4 dental implant protocol, explains the evolution of this revolutionary treatment concept at the 22nd Annual Meeting of the European Association for Osseointegration (EAO). The All-on-4 treatment concept is an excellent solution for patients with little or no bone tissue. The All-on-4 technique delivers a fixed bridge of twelve teeth, without the need for bone grafts, providing the patient with functionality and aesthetics the same day the dental implants are placed.

Video: EAO 2013 Nobel Biocare: The evolution of the All-on-4 treatment concept on YouTube.

From our speaker forum at EAO 2013: Paulo Malo on the evolution of the All-on-4 treatment concept.

Question from LinkedIn: Why did it take so long?

Answer: Speaking of placing dental implants in cadaver bone, there is very little value in this exercise because cadaver bone is similar to any other inanimate object like wood, plastic or metal. Might as well try them in soft wood!

Placing dental/orthopedic implants in humans and animals is different than cadaver bone, wood, plastic and metal in different ways:

  1. The recipient site in live bone undergoes immediate and continuous change following the placement.
  2. More importantly, what is considered “debris,” “dust” or “shaving particles” when dealing with inanimate objects, including cadaver bone, is live autogenous bone graft material when dealing with live bone and will integrate both with the metal and bone in due time.
  3. Most importantly and specially in any press fit design, excessive compressive forces, as long as it does not “break” the cadaver bone and other inanimate objects, goes unpunished. Whereas in live bone, compressive forces beyond a certain measure will cause necrosis of the surrounding area and failure of the fixture.

I think an implant design that takes into account and has actual physical features that take advantage of the above three points will be a smarter implant than what we currently have.

Parsa Zadeh

DDS and Founder at Dental Evolutions® Inc.

Top Contributor


I think one positive conclusion we can draw from all the above discussions is that, at least in select cases, four implants can be sufficient to support an entire arch. Whether to angle the two distal ones or set them upright, I guess depends on many factors, most important being how familiar the surgeon is with the All-on-4 protocol.

In terms of a patient’s ability to clean underneath the screwed down denture, we must think of the prosthesis less as a denture and more like a hygienic pontic of a bridge.

If you make the tissue surface like a saddle, you invite lot of patient complaints about food getting caught underneath. The tissue surface is best shaped like a “bullet” with the tip just touching the crest of the ridge. Patients will have more food impaction while eating, but the food can easily be removed by tongue and perhaps a quick rinse. There is no undersurface for the food to get caught under.

Parsa Zadeh

DDS and Founder at Dental Evolutions® Inc.

Top Contributor


One more thing about the zirconia and porcelain screwed down implant-supported dentures — they look great in magazines, but I personally do not feel comfortable to have absolutely no cushioning from the occlusal surface to the implant bone interface. I have of course no knowledge of this being a problem, but just using some logic and knowledge of rigidity of porcelain, zirconia, titanium and bone make me not want to have such rigid prostheses.

I also wonder how all these vibrations effect the TMJ surfaces in long term.

As Jeffery pointed out, we have all seen what happens to the acrylic teeth after five to 10 years of use on implants; imagine, especially in the presence of parafunction and in the absence of acrylic to wear down, what would give in?

Parsa Zadeh

DDS and Founder at Dental Evolutions® Inc.

Top Contributor


Michael, I sincerely hope that you successfully conduct whatever study you need to do to get your implant cleared.

Every dentist out there and the population in general will benefit from greater choices in implant designs and protocols. Sometimes, we are so excited about something that we let emotions take over our logic! I have done this a million times. So, let us make sure we have enough evidence for safety and efficacy of any new product we introduce, and equally important, let us make sure we have proof for any superiority claims we make for those new products.


  1. What Do You Think About 3D Printers for Production of Implants and Other Dental Prosthodontics and Appliances?


Question from LinkedIn:

“Hi Everyone, this company is coming up with a 3D printed dental implant that has a hydrophilic surface and a hybrid internal hex and conical connection. What do you think?” — G.B.


We (Dental Evolutions® Inc.) have had a plastic filament 3D printer (Makerbot) for over a year now and it works okay for larger objects. We have also explored and attempted 3D printing of stainless steel from outside vendors. We actually got a few drill bits and mounting instruments manufactured by printing 3D stainless steel.

Both our experiences show that currently commercially available 3D printers do not have the precision that is required for implant connection fixtures. Yes, they claim accuracy to a few microns, but their software is not sophisticated enough to produce that precision in complex geometrical shapes.

As for metal 3D printing, with the current technologies where metal is sprayed and a laser melts it to one piece, the finished product will have a very rough surface!

Of course that kind of roughness may be a blessing in disguise for the bone-implant interface, but it would be an obstacle in the fixture and soft tissue contact areas.

We considered polishing the surface, but the irregularities were too much, and it went over the tolerances. The drill bits were totally useless as the rough edges were far from being able to cut.

I am sure the 3D printing technology will get there for the precision and smoothness that we are looking for but they are not there yet.

So, to answer the question of this thread, yes the surface could be very hydrophilic, but I am curious to see how the hybrid internal hex functions.

Another viability of a manufacturing technique is its cost. 3D printing is, and for a foreseeable future will be, a costlier technique to manufacture dental implants. In absence of any specific advantage, I do not see why we should consider a more expensive and for now inferior result technique.

Few colleagues mentioned biocompatibility of polyetherketoneketone, or PEKK (also commercially known as PEEK). Just because a material is suitable and approved for implantation in the body does not mean it would be suitable as a dental implant. For a dental implant, material must be:

  1. It should not disintegrate/dissolve in the body and must not be resorbed by cellular activity.
  2. (I just made up this word!) I mean it should be able to osseointegrate, which means osteoblasts must not “see” it so that they keep growing into it.
  3. Strong enough to withstand millions of cycles of masticatory forces in diameters of 3 to 4 mm.
  4. (Another made up word.) The clinician must be able to attach an abutment to it in a manner safe for the patient, by means of a screw or adhesive.

For now, the only material that satisfies (proven to satisfy) all of these criteria is titanium and its alloys. Zirconia is the runner-up, but it has many shortcomings and disadvantages at this point.


  1. How Narrow Should Narrow Implants Be?

As many of you know, I am developing the next generation of dental implants, and in the process of design, I have to do survey research. Recently, I posited a question to the dental community:

Most of the implants we place are between 4-5mm in diameter. However, there are times when narrower implants are desirable, such as in the upper lateral incisor and lower incisor, in addition to an occasional closed space for a premolar. Considering the fact that we need between 1-1.5mm (any consensus of whether it should 1.5mm, or is 1mm sufficient?) of alveolar bone around the dental implant for the stability of the crestal bone and minimal bone loss, how narrow should the narrowest implant be?

The width of the neck of the lower central incisors are between 3.6-3.8mm, according to my measurements. In average, the 3.5mm implant should suffice to not encroach on the interdental alveolar bone in this region. However, interproximal stripping of these teeth for orthodontics sometimes brings these teeth closer to each other, and perhaps that is when an implant narrower than 3.5mm would be desirable.

Personally, I have not felt the need for anything narrower than 3.5mm. I would like to invite my colleagues’ comments about how frequently they will need to place an implant less than 3.5mm. In my opinion, it boils down to how wide the thickness of the bone should be between the implant and the adjacent teeth. If 1-1.5mm is sufficient, then a narrower implant than 3.5mm would not necessary. If you try to keep it at 1.5mm, then you may need narrow implants in some cases.


  1. Using Charcoal for Whitening

Here is a question I received in my email:

Dr. Zadeh,
Have you heard much about this technique?
Do you know how abrasive activated charcoal may be. I assume this form is NOT water soluble.

Hello T.,

I went through all the links you enclosed.

Yes, activated charcoal is a great adsorbent. It is currently and widely used as part of water filter systems and refrigerator deodorant.

Does it whiten the teeth? It may if it sits on the teeth for a long time. However, I think there is more perception of whitening after you rinse out all the carbon from your teeth than there is actual whitening.

I also think you get most of the whitening effect from scrubbing the black stuff from your teeth, hence removing the superficial stains. I do not believe anybody is as determined to really scrub the hell out of the teeth as someone who has all their teeth covered with charcoal!

The most effective whitening for the teeth is using an oxidizer like a peroxide product. In dentistry, we use carbamide peroxide in various strengths. In the past, there use to be a smoker’s toothpaste; it was a paste with very coarse abrasive that effectively removed smoking stains from the teeth. Such an abrasive product really does not have any place in today’s environments. Cigarette stain is best and safely polished off by the hygienist’s polishing cup. For stains in hard to reach areas, we can use a product called Prophyjet by KAVO. It is a high pressure spray of scented sodium bicarbonate with water. It penetrates the smallest crevices between the teeth and removes any stain.

To maintain the whiteness of your teeth, and in absence of any conditions that needs special treatment, you can use a toothpaste containing carbamide peroxide as your day-to-day toothpaste. The only adverse effect of a whitening toothpaste is potential for sensitivity. Also remember, if you have just had any oral surgery, check with us if you can use any peroxide product.

As far as charcoal is concerned, keep it out of your mouth. Unlike what some of these sites mention, commercial toothpastes are NOT poisonous, and just because something is found in nature does not mean it is harmless or useful for everything.

  • Zadeh


  1. Ultimate CR Registration, Under Sedation

Centriculation is defined as uppermost forward most of the condyle to the eminentia with the disk interposed. In full-mouth rehabilitation cases, it is important to register the position of the lower jaw to the upper jaw with the joint in this centriculation position so that we can build the centricual occlusion. Traditionally, we have been using splint therapy to gradually find this centriculation position. The splint therapy is meant to create an ideal physiologically acceptable occlusion for the patient so that the neurological reflexes would be inhibited, causing relaxation of the masticatory muscles and allowing the condyle to rest against the eminentia over the disk.

The reason for this gradual settlement are twofold. The first reason is when there is a fulcruming in occlusion and the condyle distances itself from the disk, areolar tissues and other adjacent soft tissues tend to occupy that space. The second reason is the muscle tone that is created as a defensive mechanism to prevent the trauma to the teeth and periodontia by holding the condyle away from the disk, during function and rest. Splint therapy, by creating the ideal occlusion and removing all the reflexes, will slowly relieve the muscle tone, and as the condyle starts to settle, the areolar and other soft tissues get displaced from the space between the condyle and the disk.

My years of experience with doing splint therapy followed by full-mouth rehabilitation have shown that the full-mouth rehabilitation preparation session is usually carried on under sedation. As a result of the complete muscle relaxation, the condyle usually further settles beyond what the splint therapy had achieved. Therefore, this often changes the plan of treatment, even when the treatment has already started and is well in progress. In order to avoid these surprise changes and in cases where the splint therapy cannot bring total masticatory muscle relaxation, I have decided to sedate the patient at the end of the splint therapy and before the ultimate treatment planning to take advantage of the relaxed muscles to register the true centriculation. This is done before any treatment is started, and the findings can be discussed with the patient at a subsequent date when he or she is fully awake and alert.


  1. The All-on-4 Dental Implant Protocol

Howard M. Steinberg, DMD, MDS

Prosthodontist Emphasizing Dental Implants, Restorative, Reconstructive and Cosmetic Dentistry

Top Contributor

In a recent interview with Randy Alvarez on The Wellness Hour, I explain how the All-on-4 dental implant protocol is the best treatment option for patients missing most or all of their teeth.

Comments by Dr. Parsa T. Zadeh DDS, MAGD, FICOI

All-on-4 has a nice ring to it, but I would not declare it the best treatment for the edentulous arch, unless I am representing Nobel! An economical and easy fixed implant-supported prosthesis, yes, but definitely not the best. A much better, more stable prosthesis would be all-on-six or all-on-seven or even eight, depending on the jaw size and patient’s parafunctional habits. I cannot believe anyone with slightest engineering common sense can argue that cantilevering distal extensions (with three teeth distal to the foramen {full arch} off of a severely angled implant, in absence of any proprioceptive feedback {fully edentulous}) is better than seating the prosthesis upright, supported by six to eight implants from second molar to second molar.

I have nothing against all-on-4; it has its own advantages and indications. But it is a compromised treatment and should be used only when more stable treatment is not feasible for one reason or the other.