Astra Tech and Brånemark system implants: a 5-year prospective study of marginal bone reactions

: This paper describes the 5‐year results of a comparative study between Astra Tech and Brånemark system implants. The aim was to compare the systems primarily with regard to bone level changes, and also with regard to other variables of interest. Sixty‐six patients with edentulous jaws were included in the study. Randomisation schedules were used to allocate the patients to the two implant systems. 184 Astra Tech implants with a titanium‐blasted surface and 187 Brånemark implants with a turned surface were used. The implants were inserted with a two‐stage technique and the insertion followed the routines for the respective implant system. All patients were provided with full‐arch fixed bridges. All patients were followed up with clinical and radiographic examinations from fixture insertion to the 5‐year follow‐up. The total mean bone level change in the upper jaw between fixture insertion and the 5‐year examination was −1.74±0.45 mm at the Astra implants and −1.98±0.21 at the Brånemark implants. The corresponding values for the lower jaw were −1.06±0.19 for Astra and −1.38±0.17 for Brånemark. The major postoperative changes of the marginal bone level took place between fixture insertion and baseline. During this period, there was also a different pattern of bone remodelling between the implant systems. Between baseline (prosthesis connection) and the 5‐year examination, the marginal bone level changes were small, with no difference between the implant systems. The implant stability was examined with the supraconstructions removed. At the 5‐year examination, the survival rate for Astra Tech implants was 98.4% and for the Brånemark implants it was 94.6%. The difference was not statistically significant. Résumé Ce manuscript décrit les résultats après cinq années d'une étude comparative entre les implants Astra Tech et ad modum Branemark. Le but a été de comparer les systèmes surtout en ce qui concerne les variations du niveau osseux, mais aussi en ce qui concerne d'autres variations montrant un intérêt. Soixante‐six patients avec des mâchoires édentées ont été inclus dans cette étude. Ils ont été répartis au hasard dans un des deux systèmes implantaires. Cent quatre‐vingt‐quatre implants Astra‐Tech avec une surface en titane soufflée et 187 implants Branemark avec une surface usinée ont été utilisés. Ces implants ont été insérés par une technique en deux étapes et ces insertions suivaient chacunes les étapes proposées par leur système. Tous les patients ont