What materials offer the best prognosis in sinus floor or ridge augmentation? A new systematic analysis of the literature shows the advantages of xenogeneic bone substitutes such as Geistlich Bio-Oss.
The choice of augmentation material can influence the outcome of regenerative treatment, this is the conclusion of a new publication by Tara Aghaloo and Peter Moy. The authors conducted a comprehensive review of the literature on the implant survival rate in augmented bone.
They analysed human clinical studies published between 1980 and 2005 that included at least 10 patients and contained an analysis of the implant survival rate over at least 12 months. Studies of ridge augmentation and sinus floor augmentation were included. Ninety publications met the requirements of the literature analysis. The majority of these articles dealt with sinus floor augmentation and guided bone regeneration.
Xenogeneic material for sinus
Sinus floor augmentation accounted for the greatest proportion in the literature analysis. The analysis comprised publications with a total of 5,128 implants that had been followed up for 12-102 months.
Among the tested augmentation materials, a xenogeneic bone substitute exhibited the highest implant survival rate (fig 1). All of these studies had been conducted with Geistlich Bio-Oss (Geistlich Biomaterials, Wolhusen, Switzerland). High implant survival rates were also found with allogeneic products, that is, substitutes of human non-autologous origin.
Autologous iliac crest grafts, in contrast, demonstrated much lower survival rates. This might be associated with the increased risk of premature resorption of these autologous grafts, which does not occur with slowly absorbed bone substitutes like Geistlich Bio-Oss. In an animal study, Schlegel et al found a reduction of 40 per cent in the volume of the autologous augmented material. In contrast, when a slowly absorbed bone substitute (Geistlich Bio-Oss) was used in the study, the volume loss was only 16.5 per cent. A series of other studies confirms the augmented volume is preserved when Geistlich Bio-Oss is used.
Synthetic bone substitutes also come off relatively poorly in the literature analysis with an implant survival rate of only 81 per cent and wide variation. These results may indicate poorer osteoconduction compared with xenogeneic bone substitutes. Artzi et al found in a histological study the proportion of newly formed bone was significantly greater when Geistlich Bio-Oss was used than with a synthetic beta-TCP.
A further interesting result of the literature analysis by Aghaloo and Moy was that addition of PRP, fibrin or venous blood does not appear to confer any clear advantage. However, the authors comment the number of relevant studies included in the analysis is relatively small.
Successful technique
Among the techniques for augmentation of the alveolar ridge, GBR and osteodistraction show very good results (fig 2). The survival rate of the implants was 95.5 per cent for GBR over an evaluation period of 12–74 months and 94.7 per cent for distraction osteogenesis. This figure is based on the results of a total of 1,232 implants (GBR) and 256 implants (distraction). Onlay grafting yielded a survival rate of 90.4 per cent with 986 implants.
The authors conclude that, among the methods of ridge augmentation, only GBR is adequately documented in the literature with long-term studies.
Supported results
Even though Aghaloo and Moy comment the variability of the methods used in the individual studies made the literature analysis difficult, such an analysis has a major benefit for practice: the results of different working groups are summarised and evaluated. If different working groups arrive at similar results and conclusions independent of each other and despite differences in the operative details or study design, these are very well supported and thus have a high degree of general applicability.
The xenogeneic material (Geistlich Bio-Oss) used in the studies for sinus floor augmentation appears to demonstrate advantages in treatment prognosis compared with both autologous iliac crest grafts and synthetic materials. This might be attributable to the high biofunctionality of the material, which is distinguished by a great resemblance to autologous bone, so that it is accepted particularly well by the human body and offers the great advantage of protection against resorption through its volume stability.
References available on request.