Restoring All On Four in Edentulous Mandible?

I hope I can solicit some responses on the subject of restoring an edentulous mandible with an All-on-4 approach. Does anyone have any experiences in restoring an edentulous mandible with an All-on-4 in various retentive overdenture modalities such as:
1. All four abutments are ball abutments
2. Two most distal abutments are ball attachments and the two most anterior abutments are splinted with a Hader bar
3. All four abutments are splinted with a Hader bar
There are several issues to be addressed.  The main two are which modality is most retentive? Second, which provides the least amount of stress on implants, and therefore potentially improves long term prognosis?  The greatest lateral stresses on the implants occurs during chewing and removal of the overdenture.

Your response based on experience, not opinion, would be greatly appreciated.



11 thoughts on “Restoring All On Four in Edentulous Mandible?

  1. FRANK says:

    Your best bet for restoring a mandible on four implants would be a dolder bar.
    The implants are splinted with the bar.
    you have distal extension.
    Al chewing is done on the implants, not on the gums.
    Very stable.
    easier to clan and maintain than a fixed restoration.

    Locators and balls will not allways satisfy the patients. They will feel a group pepper or rasberry pit undr the denture while chewing. There is a need to change the locator nylons every so often, etc…
    I hope this helps

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  2. Daniel P. Camm says:

    The term “All-on-4”, as developed by Dr. Paulo Malo, refers to the following specific parameters:
    1. The posterior implants are tilted 30 degrees to the distal and placed just anterior to the mental nerve (or the anterior wall of the sinus in the maxilla), so that the abutment exits the tissue in the 2nd bicuspid area. This also allows the use of longer implants.
    2. The prosthesis is fixed to the implants (cannot be removed by the patient), usually screw-retained, and has 1 or 2 teeth cantilevered distal to the posterior abutments. This is possible because of the biomechanics of tilting the posterior implants.
    If the implants are all axially aligned, it is not a true “All-on-4”. What you are asking about is not an “All-on-4”. It is a removable, implant-supported overdenture. Saying that, I will say that I have been doing the removable implant dentures since 1987. I have been doing the true All-on-4 procedure since 2007.
    This is my experience with the removable dentures in the mandible:
    1. Three or four implants connected with a Hader bar is the most stable restoration. I have done it with 3 Hader clips or with an anterior Hader clip and an O-ring distal to the posterior implants. When everything lines up perfectly, patients find these restorations to be very stable and retentive.
    2. Three implants NOT splinted together. I have used O-rings, ball-cap snaps, and Locators on these. I have had poor success with Locators, even though others report that they love them. I find that they are not very retentive and require a lot of work to get them aligned correctly. I prefer O-rings. They are retentive, easier to align, and less stress on the implants.
    By far, my preference is the All-on-4 technique. I have done over 150 cases using the technique. It requires a lot of hands-on experience to properly learn the technique, but patients LOVE these prostheses. They feel like they have their own teeth back. Learning how to do this procedure has caused a big paradigm shift for me. I approach the restoration of edentulous arches completely different from my previous approach, and I have much more confidence that patients will be really satisfied.

    Daniel Camm

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  3. Neil Bryson says:

    I have done only about 100 of these all on 4 but all are still in function except when the patient has expired(they died of old age!). I consider all on four to include removeable appliances and have found greater success with removable than fixed. My first case was in 1984 and that patient still has all four implants even though we have replaced the Hader bar once and the clips many tines. The Hader bar splints all four implants together and is very stable. The clips for the bar are your weak spot but new improvements over the last 15 years such as encasing the clip within a metal housing have lengthened their lives. It will vary with each patient and their occlusal forces. Some patients need replacement of the clips each year and some go several years before replacement. The beauty is that the clips take the brunt of the forces and not the implants or the bone. As you can tell, the Hader bar is my favorite but there are other bars out there that work well. I also like a total screw in or “fixed” appliance but the cost factor is a big consideration. I have done probably 40 to 50 fixed but I feel the bone and implants take a greater beating when you only have four supporting the appliance. Hader clips, if kept tight, will provide ample retention. I am a little more fanatic about hygiene than some operators so I require the patient to see us every four months to completely remove the Hader Bar and inserts to clean and polish. This keeps the gingavae healthy and prolongs implant life. I just cleaned one this afternoon that has been in place since 1993 and still going strong. I do find that over the last ten years that I have done so many more mini implants with o-rings than the Hader because of costs. I still feel that Hader bars are superior but in all honesty the minis and I-rings provide a wonderful result for less cost to the patient. It is our obligation to present ALL treatment options when planning. But in your case you have four good implants and if the position of the implants is acceptable then I would do the Hader. We are blessed as Dentists to have so many options that all work and make us heroes to our edentulous patients. I wish you well in whatever option you choose.

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  4. Roxanne Merizalde says:

    I’m a patient whose radionecrotic left mandible was replaced by an oseteocutaneous flap in 2014. In addition I have rather severe trismus. The gap between my teeth on the right might be a 1/2″ on a good day.
    Would any of these implant options possibly work for me? I’m not a dentist or a doctor, but I’ve been following this site for a while. I do understand that you and I have no way of being certain of the feasibility without actual measurements and scans.

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  5. Jeffrey says:

    To Daniel P. Camm,
    You are a dentist not a follower of a religion. Just the mere fact that implants manufacturers provide removable attachments to work with multi-units abutments, that alone should tell you where the concept is directed. I don’t know what Paulo Malo had in mind when he came up with a fundamental engineering project of placing a structure on four pillars, but I am almost sure he wasn’t fixed on any idea on what or how to place any restoration on these foundations.

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  6. Dr R Y says:

    I have placed 4 pre mental implants with removable over denture based on telescopic crown with precious metal, in 2012 ,patient is satisfied yet, I prefer removable prosthesis rather than fix

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  7. Paul says:

    All on Four is nothing but a name to a particular protocol of placing implants. One cannot take it literally. All does not mean 16 teeth in one jaw. The distal extension of whatever restoration should not go beyond 1.5x distance between anterior and posterior abutments.

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  8. Daniel P. Camm says:

    Jeffrey:
    I don’t quite understand your comment. Please restate it. I will say this:
    When I was first exposed to the All-on-4 technique, I was intrigued by it but did not completely understand it. So I spent time with Dr. Malo, Dr. Robert Schroering, Dr. Ken Parrish, and Dr, Stephen Balshi, all of whom I consider experts in the technique. Not only did I watch them perform the procedure, but I also read their papers on it. They were all VERY consistent and specific about how the implants had to be placed, how the restorations had to be made on these implants, and the biomechanical principles that made the technique successful. What they stressed was that deviation from any of the principles could lead to failure of the technique.
    In practice, I found that to be true. In the few cases that I made changes to the principles of the technique, I had failures that were very difficult to deal with. I have also had cases that were failing referred to me that were completed by other dentists. They were failing because the dentists violated the principles of the technique.
    The mistake, or the “trap”, that has snared many dentists and has to be avoided is that the All-on-4 works on every edentulous patient or every soon-to-be-edentulous patient. It does not. That is when astute diagnostic skills come into play, and the dentist needs to be a really good clinician. I have failed at that a few times, and it has cost me dearly. That is why I feel that it is so important to study the specific technique that Dr. Malo and others so diligently proved works.
    There are other ways to restore an edentulous arch with a fixed restoration. Placing 6-8 axially aligned implants with a fixed restoration certainly can work well. The term All-on-6 or All-on-8 can be tossed around to refer to this. But it is not the same principle as the true All-on-4 technique. The true All-on-4 refers to the following situations:
    MAXILLA: There is very little bone distal to the 1st bicuspid region and coronal to the sinus. The only way to place 6 implants would be to do bilateral sinus grafts. The All-on-4 procedure can allow the placement of a fixed restoration with 1st molars on it without doing sinus grafts.
    MANDIBLE: There is very little bone distal to the 1st bicuspids, over the alveolar nerve, because the posterior teeth have been missing for a long time. Posterior vertical bone grafting is very difficult and unpredictable. These cases usually could not be restored with a fixed restoration. The only choice was a snap-on overdenture. The true All-on-4 technique has made fixed restorations in these cases possible and very predictable.

    Daniel Camm

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  9. Daniel P. Camm says:

    Roxanne;
    It sounds like you have a very complicated situation. I have seen implants works in these situations, but it is not possible for me to comment on the feasibility of implants for you without a lot of diagnostic information. And I do not mean just x-rays, CT scans, photos, etc. You need to be physically examined by a really good implant dentist. I recommend that you go to the website of the American Board of Oral Implantology (www.aboi.org) and locate a Board-Cerified Implant dentist in your area.
    Dr. Daniel Camm

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