Tomas AlbrektssonProf. Tomas Albrektsson, MD, PhD, ODhc, RCPSG began working on dental implants with Per-Ingvar Brånemark in 1967 and has since published many papers on osseointegration. As Guest Editor of Clinical Implant Dentistry and Related Research 2019;1-4 Supplement, he gives an overview of recently published research on the new Xeal abutment surface and TiUltra implant surface, and he shares his views on the importance of company-driven research.

In the Supplement of the latest edition of Clinical Implant Dentistry and Related Research, seven scientific papers present novel implant and abutment surface innovations, namely the new anodized abutment surface, Xeal, and the implant surface, TiUltra, with gradually increasing oxide thickness and surface roughness towards the apex. Before giving an overview of these surfaces, I would first like to comment on the background of this research from another angle – that of manufacturer or company-directed organized research.

Mimics can be cheap in the short term, but costly in the long term

Some people claim that implants are just commodity products; products that can be sold cheaply without any need for experimental or clinical documentation, so long as they bear some resemblance to other scientifically documented products. I fear that this is one of the major threats to osseointegrated implants today. What is cheap in the short term may in fact prove costly in the long term.

When we analyzed copy-cat implants from several manufacturers in our laboratories, we found clear microscopic and sometimes even macroscopic differences between the copies and the implants they are trying to mimic1. At times we find it difficult to understand what went wrong in the attempts to manufacture copycat medical devices intended to be placed in human beings. One reason for clinical problems might be organic surface impurities2 this may possibly be behind the clinical disasters seen with cheap implants. Other reasons for the clinical problems observed may be the misfit of components3, choice of raw materials4 as well as impurities from the manufacturing process.5

To avoid the risks of undocumented implants, our discipline must strongly welcome all research done by responsible companies to increase our knowledge about oral implants. Nobel Biocare has devoted many years of research both on its own and in combined efforts with different universities to increase our knowledge and further improve results of oral implants. Our oral implant discipline will benefit greatly from this research.

Nobel Biocare’s research enables the dawn of the Mucointegration™ era

Nobel Biocare has recently introduced further developments in the applied use of surface science, with the TiUltra implant surface and Xeal abutment surface.

Abutments have been the focus of much less research than the bone anchored part of the implant. We need to understand that P-I Brånemark, the father of implantology, had little possibility to devote so much research to abutments. His own machined titanium device was mainly based on empirical data coupled with his unique – almost intuitive – scientific way of thinking. But he had already realized by the 1960s, before any other university professor in the world even believed in oral implants, that abutment surfaces ought to be smooth. The placement of his first clinical implants was indeed a challenge due to the fact that the oral cavity may be described as a sea full of bacteria. As we suggested in a recent paper6, bacterial defense is usually provided by a combination of inflammatory and immunological cells, which does not contradict potential benefits of additional bacterial resistance due to the surface.

Per-Ingvar Brånemark

Brånemark had little possibility to devote research to abutments, but he was aware that the surface should be smooth.

Today, six decades of scientific research and extraordinary product developments, primarily focused on the osseointegration of oral implants, have provided the strong-enough foundations for greater abutment-focused research and development. This is to achieve not just bone attachment, but soft tissue attachment too, with the Mucointegration™ process.

Newly published papers in the Clinical Implant Dentistry and Related Research Supplement on osseointegration and the new Mucointegration™ era in surface technology, include three studies supported by Nobel Biocare, which compare conventional machined abutments to anodized Xeal abutments:

  • In one of these studies, we learn that anodized abutments have a topography with a mean height equal to machined abutments, but with regularly distributed nanostructures and with an oxide thickness of about 150 nm.7
  • Susin et al. report in vivo results of these new abutments with 6–13 weeks’ follow-up, verifying the lack of any adverse tissue reactions.8
  • Finally, one randomized, controlled clinical trial by Hall et al. spans over a period of 2 years. Here it was demonstrated that the anodized abutments showed less soft tissue bleeding upon abutment removal and significantly increased keratinized tissue height compared to machined abutments.9
Anodized abutments clinical trial

Images showing clinical appearance in relation to test (left in image, region 12) and control (right in image, region 21) abutments at 6 weeks (A), 6 months (B), and 2 years (C) post implant insertion.
Images taken from Hall J, Neilands J, Davies JR, Ekestubbe A, Friberg B. A randomized, controlled, clinical study on a new titanium oxide abutment surface for improved healing and soft tissue health. Clin Implant Dent Relat Res. 2019;21:e55–e68.

These findings indicate great clinical promise for these new types of anodized abutments.

Innovations in the surface of the implant bone-anchored portion are covered in several in vitro and in vivo studies of the supplement:

  • Milleret and co-workers inform us that the new implants have a surface roughness and oxide thickness that increase towards the apical area of the implant. This is considered by clinicians to have an advantage in implant maintenance in case of thread exposure. The collar zone was less rough, nanostructured, non-porous and had a golden hue.10
  • Comparing this new implant surface pre-clinically, the second paper by Susin et al showed no differences in osseointegration at the collar compared to TiUnite at 3, 6 and 13 weeks.11
 Implant and abutment surface

Computer-assisted representation of the implant system depicting the newly engineered surfaces (A). Microscopic characterization of the four regions of the implant system: abutment (B-D), implant collar (E-G), transition zone (H-J) and apex (K-M). Overview (B, E, H, and K) and high-magnification scanning electron micrographs of the regions of the implant system (C, F, I, and L) and 3D-reconstruction of the surface profile obtained by white-light interferometry (D, G, J, and M).
Image taken from Milleret V, Lienemann PS, Gasser A, Bauer S, Ehrbar M, Wennerberg A. Rational design and in vitro characterization of novel dental implant and abutment surfaces for balancing clinical and biological needs. Clin Implant Dent Relat Res 2019;21:e15–e24.

Wennerberg et al.12 demonstrated in a recent 10-year overview that anodized implants (TiUnite) showed significantly fewer failures in comparison with any other implant type. Time will tell whether this newly introduced anodized implant surface will display even better clinical outcomes than TiUnite has, with only an average of 1.3% implant failures.

These innovations have been designed to optimize surface chemistry, which is crucial for proteins and cells to adhere. They combine moderate roughness, morphology and surface chemistry, which together may result in an ideal surface for integration. In addition, this new surface has a protective layer to preserve the chemistry.  Importantly, continued long-term clinical observations we will be able learn the real long-term impact of this innovation in surface science.

Here we can trust that Nobel Biocare, as one of the controlled implant companies of the world, will continue documenting the actual outcome of these new surfaces over 5 and 10 years of follow up.

Other positive news for our discipline is that under the new European Union medical device regulation (MDR) coming into force, Europe will apply a stricter attitude to all medical devices, including oral implants, and increase their demand on manufacturers to provide relevant clinical data to demonstrate that new requirements are met, not only prior to the sale of all new oral implants but also to keep their existing products on the market. Nobel Biocare has already been one of the first manufacturers to undergo the new assessment, and I have every confidence in the results.

More to explore

References

  1. Duddeck DU, Albrektsson T, Wennerberg A, Larsson C, Beuer F. On the Cleanliness of Different Oral Implant Systems: A Pilot Study. J Clin Med. 2019 Aug 22;8(9).
  2. Duddeck DU, Albrektsson T, Wennerberg A, Larsson C, Beuer F. On the Cleanliness of Different Oral Implant Systems: A Pilot Study. J Clin Med. 2019 Aug 22;8(9).
  3. Karl M, Irastorza-Landa A. In Vitro Characterization of Original and Nonoriginal Implant Abutments. The International Journal of Oral & Maxillofacial Implants. 2018;33(6):1229-39.
  4. Karl M, Irastorza-Landa A. In Vitro Characterization of Original and Nonoriginal Implant Abutments. The International Journal of Oral & Maxillofacial Implants. 2018;33(6):1229-39.
  5. Duddeck DU, Albrektsson T, Wennerberg A, Larsson C, Beuer F. On the Cleanliness of Different Oral Implant Systems: A Pilot Study. J Clin Med. 2019 Aug 22;8(9).
  6. Albrektsson T, Jemt T, Mölne J, Tengvall P, Wennerberg A On inflammation-immunological balance theory – a critical apprehension of disease concepts around implants: Mucositis and marginal bone loss may represent normal conditions and not necessarily a state of disease. Clin Implant Dent Relat Res. 2019 Feb;21(1):183-189. Read on PubMed
  7. Milleret V, Lienemann PS, Gasser A, Bauer S, Ehrbar M, Wennerberg A. Rational design and in vitro characterization of novel dental implant and abutment surfaces for balancing clinical and biological needs. Clin Implant Dent Relat Res 2019;21:e15–e24. Read online
  8. Susin C, Finger Stadler A, Fiorini T, de Sousa Rabelo M, Ramos UD, Schüpbach P. Safety and Efficacy of a Novel Anodized Abutment on Soft Tissue Healing in Yucatan Mini-pigs. Clin Implant Dent Relat Res. 2019;21:e34–e43. Read online
  9. Hall J, Neilands J, Davies JR, Ekestubbe A, Friberg B. A randomized, controlled, clinical study on a new titanium oxide abutment surface for improved healing and soft tissue health. Clin Implant Dent Relat Res. 2019;21:e55–e68. Read online
  10. Milleret V, Lienemann PS, Gasser A, Bauer S, Ehrbar M, Wennerberg A. Rational design and in vitro characterization of novel dental implant and abutment surfaces for balancing clinical and biological needs. Clin Implant Dent Relat Res 2019;21:e15–e24. Read online
  11. Susin C, Finger Stadler A, Fiorini T, de Sousa Rabelo M, Ramos UD, Schüpbach P. Safety and Efficacy of a Novel Anodized Abutment on Soft Tissue Healing in Yucatan Mini-pigs. Clin Implant Dent Relat Res. 2019;21:e34–e43. Read online
  12. Wennerberg A, Albrektsson T, Chrcanovic B Long-term clinical outcome of oral implants with different surface modifications. Eur J Oral Implantol 2018;11(Suppl 1): S123-136. Read on PubMed

Posted by Prof. Tomas Albrektsson