Rehabilitation with all-on-four and all-on-six using a variable thread profile implant system: short-term success and associated bone loss

Abstract

Purpose: Although variable thread profile implants are getting widespread, literature on the success/failure associated with this implant type is scarce. Materials and methods: Nine patients were rehabilitated with fixed, screw retained dentures on four or six implants. Altogether 58 variable thread profiles, self-drilling mandibular and/or maxillary implants were inserted. The patients were followed up for 1.5 years. During this period, they were regularly checked for the clinical signs of implant failure. Bone levels were determined radio graphically, first immediately after implant insertion, and then at the 1.5-year follow-up. Bone loss was defined as the difference between the two measurements. Results: No implant failure or any complications occurred during the follow-up period. The results are similar to those reported in connection with cylindrical implants. The all-on-six technique yielded a significantly more favorable bone response than the all-on-four technique, which is probably due to the more favorable load distribution. However, the bone loss associated with the all-on-four technique was still within the range reported in connection with cylindrical implants. Conclusions: The results allow us to assume that the bone response to variable thread profile implants applied according to the applied techniques is as favorable as when cylindrical implants are used.