Mandibular full-arch FDPs on four immediate-load implants after 4 years

Method: Patients with a fully healed mandible were recruited in a university faculty clinic to partake in parallel 2-arm blinded randomized controlled trial (RCT). Between March 2006 and April 2007, 2 x 21 patients received 4 implants (Replace Select Ti-Unite, Nobel Biocare AG, Kloten, Switzerland). In the experimental group, the implants were loaded on the same day using the converted pre-existing acrylic denture. The patients used this prosthesis until receiving a permanent FDP. In the control group, a one-stage surgery procedure was used and a denture adjusted for fit over healing abutments flush with mucosa. The  permanent FDP was fabricated at least 3 months later. The 10/12-unit FDPs were made from a type-3 cast gold-palladium alloy (Olympia, Jelenko, Armonk, USA) veneered with acrylic and artificial teeth. Patients have been recalled annually since the implant placements.

Result: Six of the experimental group patients did not receive the allocated intervention, of which 4 switched study arm. Four implants failed to osseointegrate and one implant became loose after 3.5 years, all in the experimental group. Thirty-one participants returned for the 4 years clinical and radiological examinations. The crestal bone level mean changes at 4 years were identical in the experimental group 1.9mm (ITT, n=14 - 1.8mm (PP, n=10) and the control group: 1.9mm. The frequencies of biological and technical complications were low and there no differences between the experimental and the control group were observed.

Conclusion: The clinical performance of full-mouth mandibular FDPs retained by four implants does not differ depending on the two different implant loading protocols used in this trial.  Acknowledgment: This study was made possible by a grant from Nobel Biocare AG, Switzerland.