ITI implants in combination with bone grafts: design and biomechanical aspects

In this article we describe the implantation of ITI implants in combination with bone grafts. Two different cases were considered: the augmentation of an atrophic maxilla or mandible where the transplant was fixed by means of ITI implants and the implantation into free transplants fixed by means of the THORP reconstruction plate system. These indications require 2-stage procedures with submerged implants and transplants during the healing period. For this new applications, standard ITI implants were combined with specially developed new transgingival units of high manufacturing precision. The new design resulted in a maximum tightening moment of 4.0 N.m versus 1.25 N.m achievable with a conventional 2-mm screw. Dynamic testing showed that, for the range of tightening moments of 0.25 N.m up to 1.0 N.m, the loosening moment after 2,000,000 cycles remained approximately 10% above the tightening moment. For the clinical application a tightening moment of 0.35-0.5 N.m is recommended. The special design and the high precision of the extension parts results in a tight adaptation between the primary implant and the extension parts, which may be important for microbiological reasons.