Micromorphological differences of the implant-abutment junction for original and “third party” abutments on Straumann Bone Level implants

Abstract

Background: As implant therapy has become a mainstream treatment for partial and complete edentulism, offered by an ever growing number of dentists, market pressure and an increasing price competition have lead to the introduction and use of “compatible” prosthetic components often propagated to be equally reliable as the original ones. This trend is rapidly increasing worldwide with unknown consequences about the longevity of the implant supported prostheses due to the currently limited research on the risks and implications of the use of such components. Aim/Hypothesis: The aim of this study was to investigate the micromorphological differences between different commercially available zirconia, titanium and gold abutments for Straumann Bone Level implants. Material and Methods: Seven abutment types of 3 different materials were studied as follows: • Full zirconia group (Z) (3 Straumann Cares, 3 Atlantis, 3 GC Aadva Zr) • Titanium group (T) (3 Straumann Variobase, 3 Bluesky Bio KISS) • Gold group (G) (3 Straumann Gold, 3 Bluesky Bio UCLA) The 21 abutments were torqued on Straumann Bone Level RC implants according to the manufacturer’s instructions. The implant-abutment units were scanned with micro-CT and subsequently sliced in the microtome and photographed with a Scanning Electron Microscope under magnifications 10x–500x. The micro-morphology of each implant abutment unit was studied. The total length of the areas with tight contact (TC) (gap≤3 lm) was calculated in three different parts of the implant abutment junction: a)conical connection, b)lower internal connection and c)screw threads. Results: a) Internal Conical contact Group (Z): Cares had a mean of 100% tight contact left &right. Atlantis had a mean of 78.5% 63.3% respectively. GC Zr had no contact on either side. Group (T): Variobase had a mean contact of 83% (l) and 85.9% (r), while Bluesky KISS had 100% and 99.6% respectively. Group (G): Straumann had a mean tight contact of 85.8% (l) 88% (r), while Bluesky UCLA had 97.9% and 98.3%. b) Lower Internal connection: Most of the abutments, with the exception of the GC Zr, had either no tight contact with the internal part below the conical connection or only single specimens showed a minor contact within the 3 lm threshold. The GC abutments appeared to have some contact in this part of the implant, which might be due to the complete lack of contact with the higher conical part of the internal connection. c) Screw threads: The mean contact at the threads level varied between a total of 0.504 mm and 0.836 mm and engagement of 2–4 threads on each side of the slice. The screw of the Cares and Atlantis Zr abutments showed the highest average engagement (0.832 mm and 0.836 mm), while the least mean contact between screw and implant was observed for the Bluesky Ti and Gold (0.514 and 0.504). Conclusions and Clinical Implications: Major micro-morphological differences were found between the different tested abutments. These differences were not only in the extent of tight contact between the components, but they extended to the actual geometry of the abutment. Further studies are necessary in order to evaluate to what extent these differences could have clinical implications