Based on the results and within the limits of the present study, it can be concluded that ITI implant placement in conjunction with osteotome sinus floor elevation represents a safe modality of treating the posterior maxilla in areas with reduced bone height subjacent to the sinus as survival and success rates were maintained above 90% for a mean observation period of approximately 60 months. Shorter implants (8 mm implants) did not significantly fail more than longer ones (10 and 12 mm implants): the differences were small compared with the number of events; hence, no statistical conclusion could be drawn. But, from the clinical point of view, the predictable use of short implants in conjunction with osteotome sinus floor elevation may reduce the indication for complex invasive procedures like sinus lift and bone grafting procedures.

In this prospective multicenter study, non-submerged ITI implants were followed in order to evaluate their long-term prognosis in fully edentulous jaws. A total of 1286 implants were inserted in 233 consecutive patients and, after a healing period of three to six months, the successfully integrated implants were restored with 163 overdentures and 95 fixed full-arch bridges. This prospective study not only calculated the 10-year cumulative survival and success rates for the 1286 implants by life table analysis, but also evaluated the actual survival and success rates for 498 implants after at least five years of functional loading. In addition, cumulative success rates were calculated for implant subgroups according to implant length and location. Additional analyses were performed to evaluate the estimated and actual survival and success rates of the implants in relation to various prosthetic rehabilitation techniques. The 10-year cumulative survival and success rates were 95.9% and 92.7%, respectively. The actual 5-year survival and success rates of the first 498 implants that were inserted were 97.7% and 95.0%, respectively. The analysis of implant subgroups showed slightly more favourable cumulative success rates for 12 mm long implants (93%), in comparison to 10 mm and 8 mm long implants (91.6% and 89.6%, respectively). The cumulative success rate for mandibular implants (approximately 94%) was also more favourable than that for maxillary implants (approximately 91%). Patients who were loaded with both maxillary and mandibular prostheses maintained success rates well above 90%; while only implants that were inserted to support maxillary overdentures that were retained by Dolder bars showed a success rate below 90%.

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Aim Spiral family implants are a root-form fixtures with increasing thickness of tread. This characteristic gives a self-tapping and self-condensing bone properties to implants. To study spiral family implant inserted in different bone quality and connected with abutments of different angulations a Finite Element Analysis (FEA) was performed. Once drawn the systems that were object of the study by CAD (Computer Aided Design), the FEA discretized solids composing the system in many infinitesimal little elementary solids defined finite elements. This lead to a mesh formation where the single finite elements were connected among them by nodes. For the 3 units bone-implant-abutments several thousand of tetrahedral elements having 10 parabolic nodes were employed. Materials and methods The biomechanical behaviour of 4.2 mm x 13 mm dental implants, connecting screw, straight and 15° and 25° angulated abutment subjected to static loads, in contact with high and poor bone quality was evaluated by FEA. A double system was analyzed: a) FY strength acting along Y axis and having 200 N intensity; b) FY and FZ couple of strengths applied along Y and Z directions and having respectively 200N and 140N intensity. The materials were considered as homogeneous, linear and isotropic. Then the FEA simulation was performed hypothesizing a linearity between loads and deformations. Results The lowest stress value was found in the system composed by implants and straight abutments loaded with a vertical strength, while the highest stress value were found in implants and 15° angulated abutment loaded with a angulated strength. In addition, the lower is the bone quality (i.e. D4) the higher is the distribution of the stress within the bone. Conclusion Spiral family implants can be used successfully in low bone quality but a straight force is recommended.