With the All-on-4 procedure, you receive implants and a full set of non-removable, replacement teeth during a single appointment. The specialists at MALO Implants have had the unique opportunity to receive advanced, individualized training with Dr. Paulo Malo, the inventor of the All-on-4TM technique.
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OsseoNews.com is pleased to offer this interview with Dr. Paulo Malo on the innovative All-on-4TM surgical technique.
Can you give us some background on the All-on-4TM Technique? Did you develop the All-on-4TM surgical and restorative technique? What prompted you to "popularize" this technique?
Dr. Paulo Malo (Dr. Malo):
In 1993 we performed the pilot study to establish the All-on-4TM standard protocol. Since 1998, when the Nobel Speedy implant was developed, we have published a lot of retrospective studies about All-on-4TM for maxillary and mandibular rehabilitation (Editor's note: see references numbers below: 5, 6, 7 and 8).
Yes, we developed both All-on-4TM concept and the Malo Clinic Bridge.
The All-on-4TM concept is a technique that uses only 4 implants for full arch rehabilitation. By tilting the distal implants up to 45 degrees, the posterior regions (often in close approximation to the maxillary sinus and inferior alveolar nerve) are avoided and advantage is taken of the better quality bone available anteriorly. A fixed standardized surgical guide is used to aid in placement. If necessary, a cantilever can also be added to the final prosthesis. Both flap and flapless (guided) approaches are compatible with the technique. Moreover, the NobelSpeedyTM Groovy implants can reliably be placed with high insertion torque, allowing for immediate function with this technique.
The reasons the All-on-4TM technique has gained popularity are: (1) the vast numbers of the edentulous and patients with a terminal dentition who can be treated with the technique, (2) the low cost and better esthetics for the patient compared to more traditional techniques (bone grafting, more implants and multiple procedures), (3) the high success rate of the procedure (as shown in the literature), and (4) the ease and safety of the technique enables it to be performed more readily.
Which implant system do you prefer to use for the All-on-4 TM technique and why?
NobelSpeedyTM Groovy which has TiUniteTM surface that provides accelerated bone in-growth. It’s a parallel-walled implant with a tapered tip and an external abutment connection and threads all the way up to the head of the implant. This is important because an external hex allows for an increased number of threads in the area of the crestal bone to help gain maximum stabilization for immediate function. Additionally, an externally hexed implant has a more solid implant body than an internal connection, and thus the posterior tilted implant can sustain greater occlusal forces without fractures occurring. Its tapered tip is essential because we often employ the technique of under-preparation. This is the only implant that actually allows maximum expansion of the osteotomy thus providing excellent primary stability.
Can you briefly describe the indications and contraindications for using the All-on-4TM technique?
The All-on-4TM technique is usually performed in edentulous patients or those with a failing dentition who seek an immediate, fixed prosthetic solution with high esthetics.
The contraindications of this procedure are those generally applied when considering any implant surgery such as patients that have received significant radiation to the jaw, those who have a compromised immune system, or patients on IV Bisphosphonate therapy.
Could you describe some of the complications you have had with All-on-4TM . How have you dealt with these complications?
In the early days we saw fractures of the provisional prosthesis (all-acrylic) in the cantilever area. That led to a change in the technique, avoiding a cantilever in the provisional bridge. Other complications are similar to the ones that occur in the traditional procedures.
What is the single most common mistake that you have seen among dental practitioners performing the All-on-4TM technique?
It is when they do not use all bone available because they are afraid of tilting the posterior implant too much, or they do not know how to reduce the bone crest.
What is the maximum tilt of an implant fixture that can be accommodated into the All-on-4TM technique?
The maximum tilt of an implant fixture that can be accommodated into the All-on-4TM technique is up to 45 degrees in distal sites. This is due to prosthodontic and biological reasons, because we usually use 30 degree multi-unit abutments to compensate for the tilted implant. Over-tilting can lead to difficulty with the path of insertion of the prosthesis and also to bone necrosis on the top of the implant.
Do you feel that general dentists in the USA are capable of using the All-on-4TM technique or is this only for oral surgeons? What kind of training is needed to be able to utilize the All-on-4TM technique?
The good news is that any general dentist in the US, or any country in the world for that matter, can treatment plan and restore an All-on-4TM case, and therefore is able to offer it to their patients.
Remember we are talking about two phases of treatment here, a surgical phase (which includes placement of a provisional bridge) and a final prosthetic phase. The initial surgical phase may not be for everyone, as it can require large flaps and a significant amount of bone reduction. The surgeon should also be comfortable exposing anatomical landmarks like the anterior wall of the sinus and the mental foramen.
Therefore, to a large degree, much depends upon the individual training and experience of the practitioner. However, even if the general dentist who will be restoring the case is not comfortable with the “surgical phase”, he or she should have very little trouble in finding a specialist who is capable. Even if the patient had to travel to another state to complete the “surgical phase”, that patient can then return to his local practitioner for the fabrication and insertion of the final prosthesis, as well as all of the hygiene and maintenance.
We train approximately 4,000 dentists per year, who come from all over the world to learn about the All-on-4TM technique.
Are there any long-term studies to establish that tilted implants receiving off-axial loading have comparable longevity to straight implants receiving axial loading down the long axis of the implant fixture?
Yes there are. Several reports demonstrate that using implant tilting does not compromise long term outcomes of implant supported prosthetic rehabilitations: Malo et al (2005) with 1 year follow-up, Krekmanov (2000) with up to 10 years of follow-up; Aparício et al. (2001) with 7 years of follow-up; Fortin et al. (2002) with 5 years of follow-up. Additionally, we have recently submitted a study for publication with up to 10 years follow-up. Outcomes similar to parallel placed implants can be achieved.
The biomechanics of root-form implants do not appear to support, in theory, the use of tilted implants in the premolar and molar regions. What biomechanical justification can you present to justify this procedure?
Based on the literature, there are several in vitro and in vivo studies that prove that this theory is wrong. Moreover, it is possible to support an alternative hypothesis also for the All-on-4TM (which uses 2 implants tilted distally):
Zampelis et al. (2008), using finite element analysis, concluded that there is a biomechanical advantage in using splinted tilted distal implants rather than axial implants supporting distal cantilever units when comparing the coronal stress.
Duyck et al. (2000) in a study with 13 patients rehabilitated with a full-arch implant supported prosthesis (between 3 and 6 implants), evaluated the magnitude and distribution of occlusal forces in implants supporting fixed prostheses, by applying a bending force of 50N on several positions along the occlusal surface of the prostheses and during maximal biting in maximal occlusion by using strain gauged abutments. It was observed that when applying the same force, the tension moments are significantly lower when the prostheses is supported by 4, 5 or 6 implants, comparatively to 3 implants (P<0.0001), with no significant differences between 4 or 5/6 implants. It was also verified that when occlusal forces are applied on the prostheses, multiple implants well spread give axial load and low stress (implants act as “bridge posts”, distributing load), while few implants and line placement, gives bending moments and high stress (the implants act individually). Aparício et al. (2001) evaluated the stability of implants through the Periotest, and verified that despite higher mean values of the axial implants at the connection of the prosthesis, the tilted implants stability increased over time and became equal to 2 years of follow-up, and higher than the axial implants after 3 years of follow-up. In brief, the use of tilted implants allows for:
- Placement of longer implants, enhancing the area of interaction between bone and implant, and also the primary anchorage (Krekmanov 2000; Aparício 2001; Malo et al. 2003);
- A greater distance between implants, allowing the elimination of cantilevers in the prosthesis, which results in a better load distribution (Aparício et la. 2001; Fortin et al. 2002; Malo et al. 2003);
- By reducing the number of implants to four, each implant can be placed without interfering with the adjacent implants (Malo et al. 2005)
- Placement of implants in residual bone, avoiding more complex techniques of bone graft and/or sinus lift (Aparício et al. 2001; Fortin et al. 2002; Malo et al. 2005).
Is it accurate to say that you have performed over 15000 All-on-4TM procedures and have done more of these than anybody else worldwide?
Actually, the number exceeds 15,000 All-on-4TM procedures right now in all Malo Clinics worldwide. I have no doubt that we have the most experienced surgical team performing these procedures worldwide and very likely the most experienced surgical team placing implants in the world.
ON: Dr. Malo, thanks very much for taking time out of your busy schedule to educate our readers on the All-on-4TM technique.
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REFERENCES CITED IN THE INTERVIEW
1- Aparicio C, Perales P, Rangert B. Tilted implants as an alternative to maxillary sinus grafting: A clinical, radiologic, and periotest study. Clinical implant dentistry and Related research 2001; 3: 39-49.
2- Duyck J, Nan Oosterwyck H, Vanden Sloten J, De Cooman M, Puers R, Naert I. Magnitude and distribution of occlusal forces on oral implants supporting fixed prostheses. An in vivo study. Clinical Oral implants Research 2000; 11:465-475.
3- Fortin Y, Sullivan RM, Rangert B. The Marius implant bridge: surgical and prosthetic rehabilitation for the completely edentulous upper jaw with moderate to severe resorption: a 5-year retrospective clinical study. Clinical Implant Dentistry and Related Research 2002; 4:69-77.
4- Krekmanov L, Kahn M, Rangert B, Lindstrom H. Tilting of posterior mandibular and maxillary implants for improved prosthesis support. International Journal of Oral and Maxillofacial Implants 2000; 15:405-414.
5- Maló P, Rangert B, Nobre M. “All-on-Four” Immediate-function concept with Brånemark system implants for completely edentulous mandibles: a retrospective clinical study. Clinical Implant Dentistry and Related Research 2003; 5:S2-S9.
6- Maló P, Rangert B, Nobre M. All-on-4TM immediate-function concept with Brånemark system implants for completely edentulous maxillae: A 1-year retrospective clinical study. Clinical Implant Dentistry and Related Research 2005; 7: S2-S8.
7- Maló P, Nobre M, Lopes A. The use of Computer-Guided flapless implant surgery and 4 implants placed in immediate function to support a fixed denture: Preliminary results after a mean follow-up period of 13 months. J Prosthet Dent 2007; 97: S26-S34.
8- Maló P, Nobre M, Lopes I. A new approach to rehabilitate the severely atrophic maxilla using extramaxillary anchored implants in immediate function: A pilot study. J Prosthet Dent 2008; 100: 354-366.
9- Zampelis A, Rangert B, Heijl L. Tilting of splinted implantsfor improved prosthodontic support: A two dimensional finite element analysis. J Prosthet Dent 2007; 97: 255-64.