As many of us already know, dental implants are designed to facilitate an optimal level of osseointegration. However, there’s another factor that is also of great importance: soft tissue health.

The importance of soft tissue health

It has been well established that, for healthy teeth, the periodontal soft tissue not only stabilizes teeth, but also creates a barrier between the oral cavity and the body’s inside. The soft tissue’s role is quite similar when it comes to a dental implant: dense soft tissue contact with the abutment surface can act as a barrier that protects and preserves the underlying crestal bone.1 2 However, as Dr. France Lambert pointed out in a previous blog article, the anatomical features of the soft tissue adjacent to a dental implant are different to the soft tissue surrounding natural dentition. Perpendicular collagen fibers known as Sharpey’s fibers connect natural teeth to the cementum, whereas collagen fibers tend to adhere to the abutment surface in a parallel or circumferential manner, which can lead to a weaker connective interface.3

Figure 1. Comparison of periodontium and peri-implant soft tissue characteristics. (a) Sharpey’s fibers attach to the cementum of natural teeth and are oriented perpendicular to the tooth surface. (b) Peri-implant connective tissue is primarily oriented parallel or circumferentially to the abutment surface.

To achieve healthy integration and long-term dental implant success, it is essential to achieve increased mucosal tissue stability surrounding an abutment.4

Two factors that influence soft tissue attachment

It’s fairly common knowledge that the surface of a dental implant can have a significant impact on the implant’s immediate and long-term survival. What has been less frequently interrogated is the role of the abutment surface, and what procedures it should be subject to.

Figure. 2 Human gingival epithelial cells attached to the Xeal abutment surface (immunofluorescent staining of the cytoskeleton: actin-red, vinculin-green, nuclei-blue) Scale bar: 20 µm.5

As has been shown in numerous studies, an abutment with a smooth surface not only facilitates mechanical cleaning, but less plaque accumulation has also been observed compared to abutments with a rough surface.6 7 8 9 However, there are additional elements that need to be considered.

Nanotopography

The nanotopography of a surface has become increasingly important as its role in soft tissue attachment has grown clearer. The surface’s nanostructure is now believed to play a role in promoting cell–implant interactions at a cellular and protein level.10

There are a number of methods for altering the nanotopography of an abutment surface. One such preferred way is anodization, a process which involves submerging the abutment in an electrolytic fluid and applying voltage. This changes the nanotopography that in turn leads to gingival fibroblast adhesion and proliferation, as an important step in soft tissue attachment.11 12

Surface chemistry

This process of anodization also has an effect on the abutment surface chemistry and energy. Research has shown that anodized surfaces have the most hydroxyl groups when compared to sand-blasted and acid-etched surfaces13 and correlates strongly to increased hydrophilicity, or the affinity a surface has for water (or blood).14

It’s also been demonstrated in prior studies that hydrophilic abutment surfaces may assist with adhesion,15 16 17 18 supporting gingival soft tissue attachment, which has a functional biological seal for preventing microbial colonization.19

The need for a pristine surface

Once any abutment or implant has been manufactured and packaged, atmospheric elements might build up on its surface, even if it is stored in sterile packaging. These deposits tend to have a negative effect on surface energy, which is correlated with hydrophilicity and the abundance of hydroxyl groups.20 21

There is a clear need, then, for the abutment surface to remain in a pristine and unspoiled condition before use, which can be achieved through the use of a protective layer.

Xeal™ – An abutment surface for the Mucointegration™ process22 23 24

Xeal is the latest abutment surface from Nobel Biocare and, together with the TiUltra implant surface, marks the beginning of the Mucointegration™ era. A smooth, non-porous, nanostructured anodized surface, Xeal possesses a surface chemistry and topography that have been designed to achieve soft tissue attachment.25

Figure 3 Soft tissue (blue) attachment after 13 weeks in oral minipig model. © Schupbachltd.com (Nobel Biocare. Data on file.)

Though this abutment surface was only introduced to market in 2019, it is already the subject of a clinical study with two years’ follow-up in which it demonstrated a statistically significant increase in keratinized soft tissue height compared to machined abutments.26

In addition to functional benefits, its golden hue (a result of the anodization process) is beneficial in supporting a natural appearance in the transmucosal zone, which may be particularly relevant in cases where thin mucosa or mucosal recession is present.

To ensure that it is in pristine condition, Xeal is also delivered with a Protective Layer that dissolves upon contact with fluid, i.e. blood. This dry packaging technology preserves the abutment surface’s hydrophilicity and surface chemistry and protects it from hydrocarbon contamination.27

Figure 4 Layer preserves the pristine surface chemistry and hydrophilicity28
* Hydroxyl-group quantification by chemical-derivatization X-ray photoelectron spectroscopy

Through Xeal and TiUltra, Nobel Biocare’s extensive expertise in anodization technology is applied to the full implant system, from abutment to implant apex.

Conclusion

While the importance of implant surface is common knowledge, abutment surface has undergone far less intense investigation.  Dense soft tissue contact with the abutment surface can act as a barrier that protects and preserves the underlying crestal bone needed to achieve healthy integration and long-term dental implant success.29

This has been a driving factor behind the development of the Xeal abutment surface, enhancing the understanding of surface characteristics – especially surface chemistry and nanostructure – to optimize the Mucointegration™ process.

Learn more about the new Xeal abutment surface and TiUltra implant surface.

More to explore

References

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  15. Wang X, Lu T, Wen J, et al. Selective responses of human gingival fibroblasts and bacteria on carbon fiber reinforced polyetheretherketone with multilevel nanostructured TiO2. Biomaterials. 2016;83:207-218
  16. Yang Y, Zhou J, Liu X, Zheng M, Yang J, Tan J. Ultraviolet light-treated zirconia with different roughness affects function of human gingival fibroblasts in vitro: The potential surface modification developed from implant to abutment. J Biomed Mater Res Part 8 2015;1038:116-124
  17. Guida L, Oliva A, Basile MA, Giordano M, Nastri L, Annunziata M. Human gingival fibroblast functions are stimulated by oxidized nano-structured titanium surfaces. J Dent 2013;41:900-907
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Posted by Chris Kendall