Fogorvosi Szemle (Dec 2020)
Implant-abutment connection types in dental implant systems
Abstract
It is difficult for clinical dentists to keep up with the rapid development of dental implant systems. The surgical issues of implantation are mostly clarified, and no surgical revolution is expected in the near future. However, the implant-abutment connection (IAC) types are permanently being modified. Advantages and disadvantages of the most important IACs – external hex, tapered hex, external octagon, spline implant, 3-point internal tripod, 6-point internal hex, internal octagon, 12-point internal hex, Morse taper – are discussed and biological, mechanical and aesthetic aspects of IACs are detailed in the article. The article can serve as a guide to decide which connection type to use in a certain indication. Following Brånemark’s protocol, original external hexagonal implants are excellent alternatives for the treatment of anodontous patients. However, as the indications were broadened, it became necessary to modify the traditional external hexagon design, and to develop the internal connections. The increased incidence of screw loosening and fracture in the new indications has been significantly reduced by the modifications and the introduction of internal connections. In external connections the micro-motion and microleakage are more common between the components, that is why bacterial seal is less satisfactory. Conical structures provide the best mechanical and biological seal. Conical structures do not have anti-rotation properties, and therefore the insertion of a polygon or spline into the system is required. The 6-point, 12-point, 3-point internal connections are suitable for this purpose, as are Morse tapers supplemented by hexagonal or octagonal structures. In the case of angled abutments or single missing tooth is being replaced these structures are recommended. The force distribution of the internal connections is more favourable for the screw and the implant body, but it is unfavourable to the bone. In contrast to the external connections, the load on the bone is less, so this must also be considered when choosing the most suitable type. From the aesthetic point of view, internal connections provide much better results in terms of the emergence profile, the anatomical accuracy of the replacement, and the potential exposure of the metal parts.
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